- Pulmonary Hypertension
- Pulmonology (Lung) and Critical Care
- Pulmonary Disease
Associate Professor - Med Center Line, Medicine - Pulmonary & Critical Care Medicine
Clinical Director, VMWC Pulmonary Hypertension Database, Vera Moulton Wall Center for Pulmonary Vascular Disease (2006 - Present)
Director, Adult Pulmonary Hypertension Service, Vera Moulton Wall Center for Pulmonary Vascular Disease (2007 - Present)
Honors & Awards
Fellow of the American College of Chest Physicians, American College of Chest Physicians (2008)
Faculty Teaching Award, Dept of Medicine, Stanford (2007)
Young Investigator Career Development Award, Entelligence Actelion Young Investigators Program (2006-2007)
Fellow of the Year, Univ of Califronia, Irvine Medical Center (2002-2003)
Resident Research Presentation Award, Univ of Calif, Irvine Medical Center - Dept of Medicine (2001)
Case Presentation Award, ACCP - Chest 2000 (2000)
Excellence in Research Award, University of California, Irvine School of Biological Sciences (1995)
Ralph Waldo Gerard Award for Outstanding Researcher, University of California, Irvine School of Biological Sciences (1994)
Howard Huges Summer Fellowship, Harvard School of Medicine (1992 & 1993)
Board Certification: Pulmonary Disease, American Board of Internal Medicine (2006)
Medical Education:University of California Irvine (1999) CA
Fellowship:Stanford University School of Medicine (2006) CA
Fellowship:Stanford University School of Medicine (2005) CA
Fellowship:University of Irvine Medical Center (2003) CA
Residency:University of Irvine Medical Center (2002) CA
Internship:University of Irvine Medical Center (2000) CA
Super-Fellowship, Stanford University, Pulmonary Vascular Disease (2006)
Fellowship, Stanford University, Pulmonary & Critical Care (2005)
Fellowship, UCI Medical Center, Pulmonary & Critical Care (2003)
Residency, UCI Medical Center, Internal Medicine (2002)
MD, University of California, Irvine, Medicine (1999)
BS, University of California, Irvine, Biological Sciences (1994)
Community and International Work
Member PHA SLC
Pulmonary Hypertension Association
Opportunities for Student Involvement
Current Research and Scholarly Interests
1. The Utility of S100A4/Mts1 as a Biomarker in Pulmonary Arterial Hypertension (PAH).
2. Prevalence and Treatment of Insulin Resistance in PAH.
3. The Effect of EGF-Receptor Blockade and Elastase Inhibitor on Pulmonary Arteries of Patients with PAH.
4. Characterization of Pulmonary Arteries in Patients with Idiopathic and Secondary PAH by Wedge Angiography.
5. The Optimal Angle for Angiographic Evaluation of the Left Pulmonary Artery in Patients with PAH.
A 48-week Study of the Effect of Dual Therapy (Inhaled Treprostinil and Tadafafil) Versus Monotherapy (Tadalafil), 2 FDA Approved Pulmonary Hypertension Medications
The Study Hypothesis: Aggressive, upfront, dual therapy for treatment-naïve NYHA I/II/III PAH is superior to a traditional "step-up" approach. The study will evaluate: 1. Impact of dual, upfront, therapy on cardiovascular parameters in PAH as gauged by cardiac magnetic resonance imaging (cMRI) at 24 weeks and event free survival at outcome at 48 weeks. 2. Value of novel biomarkers (NT-pro BNP, Mts1/S100A4, and insulin resistance) and cutting-edge imaging technologies (cardiac MRI) as newer endpoints for clinical trials in PAH. 3. Utility of longer clinical trial design with the use of combined clinical events as time to clinical worsening surrogate
Stanford is currently not accepting patients for this trial. For more information, please contact val scott, 650-725-8082.
FK506 (Tacrolimus) in Pulmonary Arterial Hypertension
Mutations in bone morphogenetic protein receptor 2 (BMPR2) are present in >80% of familial and ~20% of sporadic pulmonary arterial hypertension (PAH) patients. Furthermore dysfunctional BMP signaling is a general feature of pulmonary hypertension even in non-familial PAH. We therefore hypothesized that increasing BMP signaling might prevent and reverse the disease. We screened > 3500 FDA approved drugs for their propensity to increase BMP signaling and found FK506 (Tacrolimus) to be a strong activator of BMP signaling. Tacrolimus restored normal function of pulmonary artery endothelial cells, prevented and reversed experimental PAH in mice and rats. Given that Tacrolimus is already FDA approved with a known side-effect profile, it is an ideal candidate drug to use in patients with pulmonary arterial hypertension. The aims of our trial are: 1. Establish the Safety of FK506 in patients with PAH. 2. Evaluate the Efficacy of FK506 in PAH 3. Identify ideal candidates for future FK506 phase III clinical trial.
Rituximab for Treatment of Systemic Sclerosis-Associated Pulmonary Arterial Hypertension (SSc-PAH)
Systemic sclerosis-associated pulmonary arterial hypertension (SSc-PAH) is a serious, life-threatening manifestation of systemic sclerosis (SSc), an autoimmune disease of the connective tissue characterized by scarring (fibrosis) and atrophy of the skin, joints and tendons, skeletal muscles, and internal organs, and immunological disturbances. One-year survival for patients with SSc-PAH ranges from 50-81%. There is currently no cure for SSc-PAH and treatment is limited to vasodilator therapy used in all forms of PAH. In recent studies, immunotherapy was shown to be effective in treating SSc-interstitial lung disease, another serious, life-threatening manifestation of SSc. In addition, there are compelling pre-clinical data and anecdotal clinical reports that suggest modulation of the immune system may be an effective strategy for treating SSc-PAH. To test this approach, this trial will determine if rituximab, an immunotherapy, has a marked beneficial effect on clinical disease progression, with minimal toxicity, in patients with SSc-PAH when compared to placebo.
Study of Incidence of Respiratory Tract AEs in Patients Treated With Tyvaso® Compared to Other FDA Approved PAH Therapies
A surveillance of respiratory tract related adverse events in patients treated with Tyvaso®(treprostinil) Inhalation Solution versus other FDA approved therapies
Unique predictors of mortality in patients with pulmonary arterial hypertension associated with systemic sclerosis in the REVEAL registry.
2014; 146 (6): 1494-1504
Background:Patients with pulmonary arterial hypertension associated with systemic sclerosis (SSc-APAH) experience higher mortality rates than patients with idiopathic disease and those with other connective tissue diseases (CTD-APAH). We sought to identify unique predictors of mortality associated with SSc-APAH in the CTD-APAH population. Methods:The Registry to Evaluate Early and Long-Term PAH Management (REVEAL) is a multicenter, prospective US-based registry of patients with previously and newly diagnosed (enrollment within 90 days of diagnostic right heart catheterization) PAH. Cox regression models evaluated all previously identified candidate predictors of mortality in the overall REVEAL population to identify significant predictors of mortality in the SSc-APAH (n=500) versus non-SSc-CTD-APAH (n=304) populations. Results:Three-year survival in the previously diagnosed and newly diagnosed SSc-APAH group was 61.4±2.7% and 51.2±4.0%, respectively, compared with 80.9±2.7% and 76.4±4.6%, respectively, in the non-SSc-CTD-APAH group (P<.001). In multivariate analyses, males aged >60 years, systolic blood pressure (SBP) ≤110 mmHg, 6-minute walk distance (6MWD) <165 m, mean right atrial pressure (mRAP) >20 mmHg within 1 year, and pulmonary vascular resistance (PVR) >32 WU remained unique predictors of mortality in the SSc-APAH group; 6MWD ≥440 m was protective in the non-SSc-CTD-APAH group, but not the SSc-APAH group. Conclusions:Patients with SSc-APAH have higher mortality rates than non-SSc-CTD-APAH patients. Identifying SSc-APAH patients who are at particularly high risk of death, including elderly males and patients with low baseline SBP or 6MWD, or markedly elevated mRAP or PVR, will enable clinicians to identify patients who may benefit from closer monitoring and more aggressive treatment. Registered at:www.clinicaltrials.gov #NCT00370214.Patients with pulmonary arterial hypertension associated with systemic sclerosis (SSc-APAH) experience higher mortality rates than patients with idiopathic disease and those with other connective tissue diseases (CTD-APAH). We sought to identify unique predictors of mortality associated with SSc-APAH in the CTD-APAH population.The Registry to Evaluate Early and Long-Term PAH Management (REVEAL) is a multicenter, prospective US-based registry of patients with previously and newly diagnosed (enrollment within 90 days of diagnostic right heart catheterization) PAH. Cox regression models evaluated all previously identified candidate predictors of mortality in the overall REVEAL population to identify significant predictors of mortality in the SSc-APAH (n=500) versus non-SSc-CTD-APAH (n=304) populations.Three-year survival in the previously diagnosed and newly diagnosed SSc-APAH group was 61.4±2.7% and 51.2±4.0%, respectively, compared with 80.9±2.7% and 76.4±4.6%, respectively, in the non-SSc-CTD-APAH group (P<.001). In multivariate analyses, males aged >60 years, systolic blood pressure (SBP) ≤110 mmHg, 6-minute walk distance (6MWD) <165 m, mean right atrial pressure (mRAP) >20 mmHg within 1 year, and pulmonary vascular resistance (PVR) >32 WU remained unique predictors of mortality in the SSc-APAH group; 6MWD ≥440 m was protective in the non-SSc-CTD-APAH group, but not the SSc-APAH group.Patients with SSc-APAH have higher mortality rates than non-SSc-CTD-APAH patients. Identifying SSc-APAH patients who are at particularly high risk of death, including elderly males and patients with low baseline SBP or 6MWD, or markedly elevated mRAP or PVR, will enable clinicians to identify patients who may benefit from closer monitoring and more aggressive treatment.www.clinicaltrials.gov #NCT00370214.
View details for DOI 10.1378/chest.13-3014
View details for PubMedID 24992469
Impact of insulin resistance on ventricular function in pulmonary arterial hypertension.
journal of heart and lung transplantation
2014; 33 (7): 721-726
Insulin resistance (IR) is an independent prognostic marker in pulmonary arterial hypertension (PAH), although the mechanism by which it engenders risk is unknown. We prospectively investigated the clinical, laboratory, hemodynamic, and echocardiographic characteristics of insulin-sensitive (IS) and IR patients with PAH.This was a prospective cohort study including well-phenotyped patients with PAH proven at cardiac catheterization. Patients were classified as IS or IR on the basis of the well-validated triglyceride/high-density lipoprotein-cholesterol ratio. Clinical, laboratory, and hemodynamic characteristics were compared between cohorts. Distance walked on the 6-minute walk test (6MWT) and echocardiograms were compared between IS and IR for the sub-set of patients that had these tests within 1 month of cardiac catheterization.Of the 111 PAH patients enrolled, 59 were IS, 25 were IR, and 27 were classified as indeterminate. Mean age was 45.8 ± 15.0 years. IR was associated with worse New York Heart Association class (p = 0.02). There were no differences in hemodynamics, biomarkers, 6MWT distance, or parameters of right ventricular function (i.e., tricuspid annular plane systolic excursion, myocardial performance index, and fractional area change) between groups. Despite similar systemic vascular resistance, parameters of left ventricular diastolic function were more favorable for IS vs IR, including mitral inflow E wave velocity (82 ± 17 vs 64 ± 19 msec, p = 0.02), E/A ratio (1.2 ± 0.4 vs 0.8 ± 0.2, p = 0.01), and lateral mitral valve E' velocity (13.9 ± 3.5 vs 10.4 ± 2.2 msec, p = 0.01).IR is associated with worse functional class and diastology compared with IS in PAH, although other prognostic parameters are similar.
View details for DOI 10.1016/j.healun.2014.02.016
View details for PubMedID 24819985
Current Clinical Management of Pulmonary Arterial Hypertension
2014; 115 (1): 131-147
During the past 2 decades, there has been a tremendous evolution in the evaluation and care of patients with pulmonary arterial hypertension (PAH). The introduction of targeted PAH therapy consisting of prostacyclin and its analogs, endothelin antagonists, phosphodiesterase-5 inhibitors, and now a soluble guanylate cyclase activator have increased therapeutic options and potentially reduced morbidity and mortality; yet, none of the current therapies have been curative. Current clinical management of PAH has become more complex given the focus on early diagnosis, an increased number of available therapeutics within each mechanistic class, and the emergence of clinically challenging scenarios such as perioperative care. Efforts to standardize the clinical care of patients with PAH have led to the formation of multidisciplinary PAH tertiary care programs that strive to offer medical care based on peer-reviewed evidence-based, and expert consensus guidelines. Furthermore, these tertiary PAH centers often support clinical and basic science research programs to gain novel insights into the pathogenesis of PAH with the goal to improve the clinical management of this devastating disease. In this article, we discuss the clinical approach and management of PAH from the perspective of a single US-based academic institution. We provide an overview of currently available clinical guidelines and offer some insight into how we approach current controversies in clinical management of certain patient subsets. We conclude with an overview of our program structure and a perspective on research and the role of a tertiary PAH center in contributing new knowledge to the field.
View details for DOI 10.1161/CIRCRESAHA.115.303827
View details for Web of Science ID 000337738900016
Whole-Exome Sequencing Reveals TopBP1 as a Novel Gene in Idiopathic Pulmonary Arterial Hypertension
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
2014; 189 (10): 1260-1272
Rationale: Idiopathic pulmonary arterial hypertension (IPAH) is a life-threatening disorder characterized by progressive loss of pulmonary microvessels. While mutations in the bone morphogenetic receptor (BMPR) 2 are found in 80% of heritable and ±15% of IPAH patients, their low penetrance (±20%) suggests that other as-yet unidentified genetic modifiers are required for manifestation of the disease phenotype. Use of whole exome sequencing (WES) has recently led to the discovery of novel susceptibility genes in heritable PAH but whether WES can also accelerate gene discovery in IPAH remains unknown. Objectives: To determine whether WES can help identify novel gene modifiers in IPAH patients. Methods and Measurements: Exome capture and sequencing was performed on genomic DNA isolated from 12 unrelated IPAH patients lacking BMPR2 mutations. Observed genetic variants were prioritized according to their pathogenic potential using ANNOVAR. Main Results: A total of 10 genes were identified as high priority candidates. Our top hit was TopBP1, a gene involved in the response to DNA damage and replication stress. We found that TopBP1 expression was reduced in vascular lesions and pulmonary endothelial cells isolated from IPAH patients. While TopBP1 deficiency made endothelial cells susceptible to DNA damage and apoptosis in response to hydroxyurea, its restoration resulted in less DNA damage and improved cell survival. Conclusions: WES led to the discovery of TopBP1, a gene whose deficiency may increase susceptibly to small vessel loss in IPAH. We predict that use of WES will help identify gene modifiers that influence an individual's risk of developing IPAH.
View details for DOI 10.1164/rccm.201310-17490C
View details for Web of Science ID 000336017200018
Blocking Macrophage Leukotriene B-4 Prevents Endothelial Injury and Reverses Pulmonary Hypertension
SCIENCE TRANSLATIONAL MEDICINE
2013; 5 (200)
View details for Web of Science ID 000323705100010
Blocking macrophage leukotriene b4 prevents endothelial injury and reverses pulmonary hypertension.
Science translational medicine
2013; 5 (200): 200ra117-?
Pulmonary hypertension (PH) is a serious condition that affects mainly young and middle-aged women, and its etiology is poorly understood. A prominent pathological feature of PH is accumulation of macrophages near the arterioles of the lung. In both clinical tissue and the SU5416 (SU)/athymic rat model of severe PH, we found that the accumulated macrophages expressed high levels of leukotriene A4 hydrolase (LTA4H), the biosynthetic enzyme for leukotriene B4 (LTB4). Moreover, macrophage-derived LTB4 directly induced apoptosis in pulmonary artery endothelial cells (PAECs). Further, LTB4 induced proliferation and hypertrophy of human pulmonary artery smooth muscle cells. We found that LTB4 acted through its receptor, BLT1, to induce PAEC apoptosis by inhibiting the protective endothelial sphingosine kinase 1 (Sphk1)-endothelial nitric oxide synthase (eNOS) pathway. Blocking LTA4H decreased in vivo LTB4 levels, prevented PAEC apoptosis, restored Sphk1-eNOS signaling, and reversed fulminant PH in the SU/athymic rat model of PH. Antagonizing BLT1 similarly reversed established PH. Inhibition of LTB4 biosynthesis or signal transduction in SU-treated athymic rats with established disease also improved cardiac function and reopened obstructed arterioles; this approach was also effective in the monocrotaline model of severe PH. Human plexiform lesions, one hallmark of PH, showed increased numbers of macrophages, which expressed LTA4H, and patients with connective tissue disease-associated pulmonary arterial hypertension exhibited significantly higher LTB4 concentrations in the systemic circulation than did healthy subjects. These results uncover a possible role for macrophage-derived LTB4 in PH pathogenesis and identify a pathway that may be amenable to therapeutic targeting.
View details for DOI 10.1126/scitranslmed.3006674
View details for PubMedID 23986401
Functional Class Improvement and 3-Year Survival Outcomes in Patients With Pulmonary Arterial Hypertension in the REVEAL Registry
2013; 144 (1): 160-168
ABSTRACT OBJECTIVE: New York Heart Association/World Health Organization functional class (FC) is associated with outcomes in pulmonary arterial hypertension (PAH). We assessed whether patients with PAH who improve from FC III to FC I/II have improved survival versus patients who remain at FC III or worsen to FC IV. METHODS: Patients aged ≥19 years with FC III PAH from the REVEAL Registry (N=982) were categorized as improved, unchanged, or worsened according to their change in FC from enrollment to first follow-up assessment within 1 year of enrollment. Kaplan-Meier estimates of 3-year survival from first follow-up and changes in 6-minute walk distance (6MWD) from enrollment to first follow-up were determined. Subgroup analyses were conducted by etiology (ie, idiopathic/familial, connective tissue disease [CTD], congenital heart disease) and time of diagnosis (ie, newly and previously diagnosed [diagnostic right heart catheterization within or ≥3 months of enrollment, respectively]). RESULTS: Overall, 27% of patients improved FC. Survival was better in patients whose FC improved (84%±2%; n=263) versus those who remained unchanged (66%±2%; n=645) or worsened (29%±6%; n=74) (all P<.001). Survival was also better in patient subgroups whose FC improved versus those who remained unchanged (idiopathic/familial [P<.001], CTD-associated PAH [P=.009], whether newly [P=.004] or previously diagnosed [P<.001]. 6MWD improvements were greater in patients whose FC improved versus those who remained unchanged in the overall (P<.001) and CTD (P=.028) cohorts. CONCLUSION: Patients with PAH who improve from FC III to I/II, whether newly or previously diagnosed and regardless of PAH etiology, have better survival versus patients who remain FC III.ClinicalTrials.gov Registration Number: NCT00370214.
View details for DOI 10.1378/chest.12-2417
View details for Web of Science ID 000321605500026
View details for PubMedID 23429998
Transplantation for Idiopathic Pulmonary Arterial Hypertension Improvement in the Lung Allocation Score Era
2013; 127 (25): 2503-2513
BACKGROUND: Lung transplant (LUT) and heart-lung transplant (HLT) represent surgical options for treating medically refractory idiopathic pulmonary arterial hypertension (IPAH). The effect of the lung allocation score (LAS) on waitlist and transplant outcomes in IPAH patients is poorly described. METHODS AND RESULTS: Adults diagnosed with IPAH and listed for transplant in the 80 months before and after the LAS algorithm was implemented (N=1430) were identified in the United Network for Organ Sharing thoracic registry. Patients were stratified by organ listed and pre- and post-LAS era. The cumulative incidences of transplant and mortality for waitlisted patients in both eras were appraised with competing outcomes analysis. Post-transplant survival was assessed with the Kaplan-Meier method. These analyses were repeated in propensity-matched subgroups. Cox proportional hazards analysis evaluated the effect of pre-listing and pre-transplant characteristics on mortality. We found that post-LAS-era patients had significantly worse comorbidities; nevertheless, both LUT and HLT candidates in this era enjoyed lower waitlist mortality and a higher incidence of transplant in our unmatched and propensity-matched analyses. On multivariable analysis, HLT and double-lung transplant (DLT) were associated with improved survival from the time of waitlisting, as was being listed at a medium-to-high-volume institution. Donor/recipient gender matching predicted post-transplant survival. CONCLUSIONS: The incidence of transplant has increased while waitlist mortality has decreased in IPAH patients waitlisted for transplant in the post-LAS era. Both HLT and DLT are predictive of survival in transplant candidates with IPAH, as is being listed at a medium-to-high-volume institution. Donor/recipient gender-matching is associated with better post-transplant survival.
View details for DOI 10.1161/CIRCULATIONAHA.112.001080
View details for Web of Science ID 000320916900014
View details for PubMedID 23697910
Characteristics and Outcome After Hospitalization for Acute Right Heart Failure in Patients With Pulmonary Arterial Hypertension
2011; 4 (6): 692-699
Although much is known about the risk factors for poor outcome in patients hospitalized with acute heart failure and left ventricular dysfunction, much less is known about the syndrome of acute heart failure primarily affecting the right ventricle (acute right heart failure).By using Stanford Hospital's pulmonary hypertension database, we identified consecutive acute right heart failure hospitalizations in patients with PAH. We used longitudinal regression analysis with the generalized estimating equations method to identify factors associated with an increased likelihood of 90-day mortality or urgent transplantation. From June 1999 to September 2009, 119 patients with PAH were hospitalized for acute right heart failure (207 episodes). Death or urgent transplantation occurred in 34 patients by 90 days of admission. Multivariable analysis identified a higher respiratory rate on admission (>20 breaths per minute; OR, 3.4; 95% CI, 1.5-7.8), renal dysfunction on admission (glomerular filtration rate <45 mL/min per 1.73 m2; OR, 2.7; 95% CI, 1.2-6.3), hyponatremia (serum sodium ?136 mEq/L; OR, 3.6; 95% CI, 1.7-7.9), and tricuspid regurgitation severity (OR, 2.5 per grade; 95% CI, 1.2-5.5) as independent factors associated with an increased likelihood of death or urgent transplantation.These results highlight the high mortality after hospitalizations for acute right heart failure in patients with PAH. Factors identifiable within hours of hospitalization may help predict the likelihood of death or the need for urgent transplantation in patients with PAH.
View details for DOI 10.1161/CIRCHEARTFAILURE.110.949933
View details for Web of Science ID 000297166100008
View details for PubMedID 21908586
Incidence, Correlates, and Consequences of Acute Kidney Injury in Patients With Pulmonary Arterial Hypertension Hospitalized With Acute Right-Side Heart Failure
JOURNAL OF CARDIAC FAILURE
2011; 17 (7): 533-539
Though much is known about the prognostic influence of acute kidney injury (AKI) in left-side heart failure, much less is known about AKI in patients with pulmonary arterial hypertension (PAH).We identified consecutive patients with PAH who were hospitalized at Stanford Hospital for acute right-side heart failure. AKI was diagnosed according to the criteria of the Acute Kidney Injury Network. From June 1999 to June 2009, 105 patients with PAH were hospitalized for acute right-side heart failure (184 hospitalizations). AKI occurred in 43 hospitalizations (23%) in 34 patients (32%). The odds of developing AKI were higher among patients with chronic kidney disease (odds ratio [OR] 3.9, 95% confidence interval [CI] 1.8-8.5), high central venous pressure (OR 1.8, 95% CI 1.1-2.4, per 5 mm Hg), and tachycardia on admission (OR 4.3, 95% CI 2.1-8.8). AKI was strongly associated with 30-day mortality after acute right-side heart failure hospitalization (OR 5.3, 95% CI 2.2-13.2).AKI is relatively common in patients with PAH and associated with a short-term risk of death.
View details for DOI 10.1016/j.cardfail.2011.03.003
View details for Web of Science ID 000292368500002
View details for PubMedID 21703524
- Chronic Thromboembolic Pulmonary Hypertension NEW ENGLAND JOURNAL OF MEDICINE 2011; 364 (17): 1677-1677
Characterization of Connective Tissue Disease-Associated Pulmonary Arterial Hypertension From REVEAL Identifying Systemic Sclerosis as a Unique Phenotype
2010; 138 (6): 1383-1394
REVEAL (the Registry to Evaluate Early and Long-term Pulmonary Arterial Hypertension Disease Management) is the largest US cohort of patients with pulmonary arterial hypertension (PAH) confirmed by right-sided heart catheterization (RHC), providing a more comprehensive subgroup characterization than previously possible. We used REVEAL to analyze the clinical features of patients with connective tissue disease-associated PAH (CTD-APAH).All newly and previously diagnosed patients with World Health Organization (WHO) group 1 PAH meeting RHC criteria at 54 US centers were consecutively enrolled. Cross-sectional and 1-year mortality and hospitalization analyses from time of enrollment compared CTD-APAH to idiopathic disease and systemic sclerosis (SSc) to systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD), and rheumatoid arthritis (RA).Compared with patients with idiopathic disease (n = 1,251), patients with CTD-APAH (n = 641) had better hemodynamics and favorable right ventricular echocardiographic findings but a higher prevalence of pericardial effusions, lower 6-min walk distance (300.5 ± 118.0 vs 329.4 ± 134.7 m, P = .01), higher B-type natriuretic peptide (BNP) levels (432.8 ± 789.1 vs 245.6 ± 427.2 pg/mL, P < .0001), and lower diffusing capacity of carbon monoxide (Dlco) (44.9% ± 18.0% vs 63.6% ± 22.1% predicted, P < .0001). One-year survival and freedom from hospitalization were lower in the CTD-APAH group (86% vs 93%, P < .0001; 67% vs 73%, P = .03). Compared with patients with SSc-APAH (n = 399), those with other CTDs (SLE, n = 110; MCTD, n = 52; RA, n = 28) had similar hemodynamics; however, patients with SSc-APAH had the highest BNP levels (552.2 ± 977.8 pg/mL), lowest Dlco (41.2% ± 16.3% predicted), and poorest 1-year survival (82% vs 94% in SLE-APAH, 88% in MCTD-APAH, and 96% in RA-APAH).Patients with SSc-APAH demonstrate a unique phenotype with the highest BNP levels, lowest Dlco, and poorest survival of all CTD-APAH subgroups. Trial registry: ClinicalTrials.gov; No.: NCT00370214; URL: clinicaltrials.gov.
View details for DOI 10.1378/chest.10-0260
View details for Web of Science ID 000285494000017
View details for PubMedID 20507945
Worldwide Physician Education and Training in Pulmonary Hypertension Pulmonary Vascular Disease: The Global Perspective
2010; 137 (6): 85S-94S
Pulmonary hypertension (PH) affects > 25 million individuals worldwide and causes premature disability and death for many. The diagnosis and treatment of PH have advanced dramatically through the development of a clearly defined diagnostic classification, an evidence-based treatment algorithm for adults with pulmonary arterial hypertension using life-saving medications, and life-saving surgical procedures. However, worldwide education and training of physicians has lagged behind advances in the management of PH. Expertise in the diagnosis and management of PH is uncommon, even though physicians receive training on PH during their graduate and postgraduate education. Advances in worldwide physician education and training in PH will require substantial organization and work. Organizations working in this field will need to work collaboratively to maximize funding for education and to optimize the achievement of educational goals. Political, economic, and cultural barriers must be identified and overcome as part of any strategic plan. Global education should include training objectives for generalist, non-PH specialist, and PH specialist physicians.
View details for DOI 10.1378/chest.09-2816
View details for Web of Science ID 000278561500011
View details for PubMedID 20522584
PPAR gamma Activation: A Potential Treatment for Pulmonary Hypertension
SCIENCE TRANSLATIONAL MEDICINE
2009; 1 (12)
The pathobiology of pulmonary arterial hypertension (PAH) involves multiple molecular pathways and environmental modifiers and is characterized by progressive obliteration of pulmonary arterioles, leading to increased pulmonary vascular resistance (PVR), right heart failure, and death in approximately 40 to 60% of patients 5 years after diagnosis. There is emerging evidence that many key genes involved in PAH development are targets of the insulin-sensitizing transcription factor peroxisome proliferator-activated receptor gamma (PPARgamma), and that pharmacological PPARgamma activation would lead to their beneficial induction or repression and subsequent antiproliferative, anti-inflammatory, proapoptotic, and direct vasodilatory effects in the vasculature. PPARgamma acts downstream of bone morphogenetic protein receptor II (BMP-RII), which is the cell surface receptor that is mutated or dysfunctional in many forms of PAH. Because our recent clinical observations indicate that insulin resistance may be an environmental risk factor or disease modifier ("second hit"), we suggest that PPARgamma-activating agents might be beneficial in the future treatment of both insulin-resistant and insulin-sensitive PAH patients with or without BMP-RII mutations.
View details for DOI 10.1126/scitranslmed.3000267
View details for Web of Science ID 000277263200003
View details for PubMedID 20371457
Insulin resistance in pulmonary arterial hypertension
EUROPEAN RESPIRATORY JOURNAL
2009; 33 (2): 318-324
Although obesity, dyslipidemia and insulin resistance (IR) are well known risk factors for systemic cardiovascular disease, their impact on pulmonary arterial hypertension (PAH) is unknown. The present authors' previous studies indicate that IR may be a risk factor for PAH. The current study has investigated the prevalence of IR in PAH and explored its relationship with disease severity. Clinical data and fasting blood samples were evaluated in 81 nondiabetic PAH females. In total, 967 National Health and Nutrition Examination Surveys (NHANES) females served as controls. The fasting triglyceride to high-density lipoprotein cholesterol ratio was used as a surrogate of insulin sensitivity. While body mass index was similar in NHANES versus PAH females (28.6 versus 28.7 kg.m(-2)), PAH females were more likely to have IR (45.7 versus 21.5%) and less likely to be insulin sensitive (IS; 43.2 versus 57.8%). PAH females mostly (82.7%) had New York Heart Association (NYHA) class II and III symptoms. Aetiology, NYHA class, 6-min walk-distance and haemodynamics did not differ between IR and IS PAH groups. However, the presence of IR and a higher NYHA class was associated with poorer 6-months event-free survival (58 versus 79%). Insulin resistance appears to be more common in pulmonary arterial hypertension females than in the general population, and may be a novel risk factor or disease modifier that might impact on survival.
View details for DOI 10.1183/09031936.00000508
View details for Web of Science ID 000263709300014
View details for PubMedID 19047320
Surrogate and combined end points in pulmonary arterial hypertension.
Proceedings of the American Thoracic Society
2008; 5 (5): 617-622
Pulmonary arterial hypertension is a rare and often devastating disease, although various effective therapies are now available. Clinical trials have used hemodynamic, cardiac imaging, laboratory, and exercise measurements as surrogate and intermediate end points in pulmonary arterial hypertension. Yet, based on the current literature, it is difficult to surmise which of these (if any) have been definitively validated. In addition, investigators have advocated the use of combined clinical end points in future clinical trials. The dependence of clinical trials and clinical management on such end points warrants a review of their use.
View details for DOI 10.1513/pats.200803-029SK
View details for PubMedID 18625754
Management strategies for patients with pulmonary hypertension in the intensive care unit
CRITICAL CARE MEDICINE
2007; 35 (9): 2037-2050
Pulmonary hypertension may be encountered in the intensive care unit in patients with critical illnesses such as acute respiratory distress syndrome, left ventricular dysfunction, and pulmonary embolism, as well as after cardiothoracic surgery. Pulmonary hypertension also may be encountered in patients with preexisting pulmonary vascular, lung, liver, or cardiac diseases. The intensive care unit management of patients can prove extremely challenging, particularly when they become hemodynamically unstable. The objective of this review is to discuss the pathogenesis and physiology of pulmonary hypertension and the utility of various diagnostic tools, and to provide recommendations regarding the use of vasopressors and pulmonary vasodilators in intensive care.We undertook a comprehensive review of the literature regarding the management of pulmonary hypertension in the setting of critical illness. We performed a MEDLINE search of articles published from January 1970 to March 2007. Medical subject headings and keywords searched and cross-referenced with each other were: pulmonary hypertension, vasopressor agents, therapeutics, critical illness, intensive care, right ventricular failure, mitral stenosis, prostacyclin, nitric oxide, sildenafil, dopamine, dobutamine, phenylephrine, isoproterenol, and vasopressin. Both human and animal studies related to pulmonary hypertension were reviewed.Pulmonary hypertension presents a particular challenge in critically ill patients, because typical therapies such as volume resuscitation and mechanical ventilation may worsen hemodynamics in patients with pulmonary hypertension and right ventricular failure. Patients with decompensated pulmonary hypertension, including those with pulmonary hypertension associated with cardiothoracic surgery, require therapy for right ventricular failure. Very few human studies have addressed the use of vasopressors and pulmonary vasodilators in these patients, but the use of dobutamine, milrinone, inhaled nitric oxide, and intravenous prostacyclin have the greatest support in the literature. Treatment of pulmonary hypertension resulting from critical illness or chronic lung diseases should address the primary cause of hemodynamic deterioration, and pulmonary vasodilators usually are not necessary.
View details for DOI 10.1097/01.CCM.0000280433.74246.9E
View details for Web of Science ID 000249038700005
View details for PubMedID 17855818
Septal curvature is marker of hemodynamic, anatomical, and electromechanical ventricular interdependence in patients with pulmonary arterial hypertension.
Echocardiography (Mount Kisco, N.Y.)
2014; 31 (6): 699-707
The objective of this study was to determine the factors independently associated with septal curvature in patients with pulmonary arterial hypertension (PAH).Eighty-five consecutive patients with PAH who had an echocardiogram and a right heart catheterization within 24 hours of each others were included in the study. Septal curvature was assessed at the mid-papillary level using the eccentricity index (EI). Marked early systolic septal anterior motion was defined as a change in EI > 0.2 between end-diastole and early systole. Inter-ventricular mechanical delay was calculated as the percent time difference between right ventricular (RV) to left ventricular (LV) end-ejection time normalized for the RR interval.Average age was 45 ± 11 years and the majority of patients were women (75%). Mean right atrial pressure was 11 ± 7 mmHg, mean PAP was 52 ± 13 mmHg, relative RV area 1.8 ± 0.9, and RV fractional area change 24 ± 8%. End-diastolic EI was 1.6 ± 0.4 and systolic EI was 2.5 ± 0.8. On multivariate analysis relative pulmonary pressure, relative RV area, and inter-ventricular mechanical delay were independently associated with systolic EI (R(2) = 0.72, P < 0.001). Independent determinants of diastolic EI included relative RV area and mean PAP (R(2) = 0.69, P < 0.001). A systolic EI >1.08 differentiated patients with PAH from healthy controls with an AUC = 0.99. Patients with early systolic septal anterior motion (44% of subjects) had lower exercise capacity, more extensive ventricular remodeling, and worst ventricular function.Septal curvature is a useful marker of structural, hemodynamic, and electromechanical ventricular interdependence in PAH.
View details for DOI 10.1111/echo.12468
View details for PubMedID 24372843
Erythropoietin upregulation in pulmonary arterial hypertension.
2014; 4 (2): 269-279
The pathophysiologic alterations of patients with pulmonary arterial hypertension (PAH) are diverse. We aimed to determine novel pathogenic pathways from circulating proteins in patients with PAH. Multianalyte profiling (MAP) was used to measure 90 specifically selected antigens in the plasma of 113 PAH patients and 51 control patients. Erythropoietin (EPO) functional activity was assessed via in vitro pulmonary artery endothelial cell networking and smooth muscle cell proliferation assays. Fifty-eight patients had idiopathic PAH, whereas 55 had other forms of PAH; 5 had heritable PAH, 18 had connective tissue disease (15 with scleroderma and 3 with lupus erythematosis), 13 had portopulmonary hypertension, 6 had PAH associated with drugs or toxins, and 5 had congenital heart disease. The plasma-antigen profile of PAH revealed increased levels of several novel biomarkers, including EPO. Immune quantitative and histochemical studies revealed that EPO not only was significantly elevated in the plasma of PAH patients but also promoted pulmonary artery endothelial cell network formation and smooth muscle cell proliferation. MAP is a hypothesis-generating approach to identifying novel pathophysiologic pathways in PAH. EPO is upregulated in the circulation and lungs of patients with PAH and may affect endothelial and smooth muscle cell proliferation.
View details for DOI 10.1086/675990
View details for PubMedID 25006446
- Response to letter regarding article, "transplantation for idiopathic pulmonary arterial hypertension: improvement in the lung allocation score era". Circulation 2014; 129 (16)
Relationship between Echocardiographic and Magnetic Resonance Derived Measures of Right Ventricular Size and Function in Patients with Pulmonary Hypertension
JOURNAL OF THE AMERICAN SOCIETY OF ECHOCARDIOGRAPHY
2014; 27 (4): 405-412
Transthoracic echocardiographic (TTE) imaging is the mainstay of clinical practice for evaluating right ventricular (RV) size and function, but its accuracy in patients with pulmonary hypertension has not been well validated.Magnetic resonance imaging (MRI) and TTE images were retrospectively reviewed in 40 consecutive patients with pulmonary hypertension. RV and left ventricular volumes and ejection fractions were calculated using MRI. TTE areas and indices of RV ejection fraction (RVEF) were compared.The average age was 42 ± 12 years, with a majority of women (85%). There was a wide range of mean pulmonary arterial pressures (27-81 mm Hg) and RV end-diastolic volumes (111-576 mL), RVEFs (8%-67 %), and left ventricular ejection fractions (26%-72%) by MRI. There was a strong association between TTE and MRI-derived parameters: RV end-diastolic area (by TTE imaging) and RV end-diastolic volume (by MRI), R(2) = 0.78 (P < .001); RV fractional area change by TTE imaging and RVEF by MRI, R(2) = 0.76 (P < .001); and tricuspid annular plane systolic excursion by TTE imaging and RVEF by MRI, R(2) = 0.64 (P < .001). By receiver operating characteristic curve analysis, an RV fractional area change < 25% provided excellent discrimination of moderate systolic dysfunction (RVEF < 35%), with an area under the curve of 0.97 (P < .001). An RV end-diastolic area index of 18 cm(2)/m(2) provided excellent discrimination for moderate RV enlargement (area under the curve, 0.89; P < .001).Echocardiographic estimates of RV volume (by RV end-diastolic area) and function (by RV fractional area change and tricuspid annular plane systolic excursion) offer good approximations of RV size and function in patients with pulmonary hypertension and allow the accurate discrimination of normal from abnormal.
View details for DOI 10.1016/j.echo.2013.12.011
View details for Web of Science ID 000334315700006
View details for PubMedID 24444659
A case of recurrent pericardial constriction presenting with severe pulmonary hypertension.
2013; 3 (2): 436-439
Chronic constrictive pericarditis (CP) is a relatively rare condition in which the pericardium becomes fibrotic and noncompliant, eventually resulting in heart failure due to impaired ventricular filling. The only curative treatment is pericardiectomy. Classically, CP does not usually cause severe pulmonary hypertension. When attempting to differentiate CP from restrictive cardiomyopathy, the presence of severely elevated pulmonary arterial pressure is used as a diagnostic criterion ruling against CP. We present a case of proven recurrent pericardial constriction following pericardiectomy presenting with severe pulmonary hypertension.
View details for DOI 10.4103/2045-8932.114780
View details for PubMedID 24015347
Pulmonary Arterial Hypertension: New Insights Into the Optimal Role of Current and Emerging Prostacyclin Therapies
AMERICAN JOURNAL OF CARDIOLOGY
2013; 111 (5): 1A-16A
Pulmonary arterial hypertension (PAH), which is a subset of pulmonary hypertension, is a group of diseases distinguished by vascular remodeling of the small pulmonary arteries with associated elevated pulmonary arterial pressure and right ventricular failure. This progressive and sometimes fatal disease occurs as an idiopathic disease or as a component of other disease states. Estimates of the incidence of PAH have varied from 5 to 52 cases/1 million population. Symptoms begin with shortness of breath with exertion and progress to dyspnea with normal activities and, finally, dyspnea at rest. Untreated patients with PAH have a 1-, 3-, and 5-year survival rate of 68%, 48%, and 34%, respectively. Treated, the survival rates improve to 91% to 97% after 1 year and 84% to 91% after 2 years. The current definition of PAH consists of 3 specific hemodynamic assessments confirmed by right heart catheterization findings. One of several important pathophysiologic mechanisms involved in PAH is pulmonary vascular remodeling, which is caused by endothelial and smooth muscle cell hyperproliferation. This is coincident with overexpression of the vasoconstrictor endothelin-1 and a reduction in the vasodilators nitric oxide and prostacyclin, which further impedes proper vasomotor tone, among other effects. Prostacyclin therapies augment the decreased prostacyclin levels in patients with PAH. The currently approved prostacyclins for the treatment of PAH include epoprostenol, iloprost, and treprostinil. Among the 3 medications, the delivery options include intravenous infusion, subcutaneous infusion, and inhaled formulations. Epoprostenol has been shown to have a positive effect on survival in patients with PAH. All prostacyclins have demonstrated improvements in functional class, exercise tolerance, and hemodynamics in patients with PAH. Intravenously and subcutaneously administered formulations of prostacyclins require continuous infusion pump administration, which presents clinical challenges for both the patient and the care provider. Dosing must be individualized and also presents a clinical challenge. Inhaled formulations seem efficacious in moderately symptomatic patients with PAH and might be appropriate when combined with an oral medication. Combination therapies are commonly used in clinical practice, with the decision to do so based on randomized controlled trial data and case study evidence. The present report provides an overview of PAH, the scientific rationale for treatment with prostacyclin therapy, and the benefits and risks of prostacyclin therapy, both as monotherapy and combined with other medications approved for the treatment of PAH.
View details for DOI 10.1016/j.amjcard.2012.12.002
View details for Web of Science ID 000315666900001
View details for PubMedID 23414683
A Preliminary Study Investigating the Quantification of Beat-to-Beat Morphological Consistency in Seismocardiogram Signals
2013 35TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC)
Ballistocardiography and seismocardiography are both non-invasive mechanical measurements of the vibrations of the body in response to the heartbeat. The ballistocardiogram (BCG) signal represents the movements of the whole body in response to cardiac ejection of blood into the vasculature; the seismocardiogram (SCG) corresponds to local vibrations of the chest wall associated with sub-audible tissue and blood movement and audio frequency heart-valve closure dynamics. This paper focuses on methods for quantifying "signal consistency"--a quantitative measure of how morphologically similar each heartbeat in a patient's recording is compared to the ensemble average taken over the recording. Before comparing each beat to the average, known physiological sources of inconsistency--such as respiratory amplitude and timing variability--are removed, then the remaining inconsistency is quantified. Previously described methods for BCG signals are expanded to fit the high-frequency (> 20 Hz) components of the SCG. The use of this method in future work could help enable proactive management of heart disease in extra-clinical settings.
View details for Web of Science ID 000341702107167
Safety and efficacy of transition from systemic prostanoids to inhaled treprostinil in pulmonary arterial hypertension.
American journal of cardiology
2012; 110 (10): 1546-1550
Pulmonary arterial hypertension (PAH) is a disease characterized by increased pulmonary pressures and chronic right heart failure. Therapies for moderate and severe PAH include subcutaneous (SQ) and intravenous (IV) prostanoids that improve symptoms and quality of life. However, treatment compliance can be limited by severe side effects and complications related to methods of drug administration. Inhaled prostanoids, which offer the advantage of direct delivery of the drug to the pulmonary circulation without need for invasive approaches, may serve as an alternative for patients unable to tolerate SQ/IV therapy. In this retrospective cohort study we collected clinical, hemodynamic, and functional data from 18 clinically stable patients with World Health Organization group I PAH seen in 6 large national PAH centers before and after transitioning to inhaled treprostinil from IV/SQ prostanoids. Before transition 15 patients had been receiving IV or SQ treprostinil (mean dose 73 ng/kg/min) and 3 patients had been on IV epoprostenol (mean dose 10 ng/kg/min) for an average duration of 113 ± 80 months. Although most patients who transitioned to inhaled treprostinil demonstrated no statistically significant worsening of hemodynamics or 6-minute walk distance, a minority demonstrated worsening of New York Heart Association functional class over a 7-month period. In conclusion, although transition of patients from IV/SQ prostanoids to inhaled treprostinil appears to be well tolerated in clinically stable patients, they should remain closely monitored for signs of clinical decompensation.
View details for DOI 10.1016/j.amjcard.2012.07.012
View details for PubMedID 22853986
- Airway Management and Perioperative Decision Making in the Patient With Severe Pulmonary Hypertension Who Requires Emergency Noncardiac Surgery JOURNAL OF CARDIOTHORACIC AND VASCULAR ANESTHESIA 2012; 26 (5): 940-944
Diagnosis and management of pulmonary hypertension associated with left ventricular diastolic dysfunction.
2012; 2 (2): 163-169
Pulmonary hypertension (PH) is commonly seen in patients who present with left ventricular diastolic dysfunction (LVDD) and is considered a marker of poor prognosis. While PH in this setting is thought to result from pulmonary venous congestion, there is a subset of patients in which pulmonary pressures fail to improve with appropriate management of diastolic heart failure and go on to develop a clinical picture similar to that of patients with pulmonary arterial hypertension (PAH). Despite the utility of Doppler echocardiography and exercise testing in the initial evaluation of patients with suspected PH-LVDD, the diagnosis can only be confirmed using right heart catheterization. Management of PH-LVDD centers on both optimizing fluid management and afterload reduction to reducing left ventricular diastolic pressures and also increase pulmonary venous return. To date, there is no clear evidence that addition of PH-specific drugs can improve clinical outcomes, and their use should only be considered in the setting of clinical trials. In conclusion, PH-LVDD remains a challenging clinical entity that complicates the management of left ventricular dysfunction and significantly contributes to its morbidity and mortality. Determination of the optimal diagnostic and treatment strategies for this form of PH should be the goal of future studies.
View details for DOI 10.4103/2045-8932.97598
View details for PubMedID 22837857
Design and validation of an endothelial progenitor cell capture chip and its application in patients with pulmonary arterial hypertension
JOURNAL OF MOLECULAR MEDICINE-JMM
2011; 89 (10): 971-983
The number of circulating endothelial progenitor cells (EPCs) inversely correlates with cardiovascular risk and clinical outcome, and thus has been proposed as a valuable biomarker for risk assessment, disease progression, and response to therapy. However, current strategies for isolation of these rare cells are limited to complex, laborious approaches. The goal of this study was the design and validation of a disposable microfluidic platform capable of selectively capturing and enumerating EPCs directly from human whole blood in healthy and diseased subjects, eliminating sample preprocessing. We then applied the "EPC capture chip" clinically and determined EPC numbers in blood from patients with pulmonary arterial hypertension (PAH). Blood was collected in tubes and injected into polymeric microfluidic chips containing microcolumns pre-coated with anti-CD34 antibody. Captured cells were immunofluorescently stained for the expression of stem and endothelial antigens, identified and counted. The EPC capture chip was validated with conventional flow cytometry counts (r?=?0.83). The inter- and intra-day reliability of the microfluidic devices was confirmed at different time points in triplicates over 1-5 months. In a cohort of 43 patients with three forms of PAH (idiopathic/heritable, drug-induced, and connective tissue disease), EPC numbers are ?50% lower in PAH subjects vs. matched controls and inversely related to two potential disease modifiers: body mass index and postmenopausal status. The EPC capture chip (5?×?30?×?0.05 mm(3)) requires only 200 ?L of human blood and has the strong potential to serve as a rapid bedside test for the screening and monitoring of patients with PAH and other proliferative cardiovascular, pulmonary, malignant, and neurodegenerative diseases.
View details for DOI 10.1007/s00109-011-0779-6
View details for Web of Science ID 000294823900004
View details for PubMedID 21735044
Pulmonary Hypertension Associated With Left Heart Disease: Characteristics, Emerging Concepts, and Treatment Strategies
PROGRESS IN CARDIOVASCULAR DISEASES
2011; 54 (2): 154-167
Left heart disease (LHD) represents the most common causes of pulmonary hypertension (PH). Whether caused by systolic or diastolic dysfunction or valvular heart disease, a hallmark of PH associated with LHD is elevated left atrial pressure. In all cases, the increase in left atrial pressure causes a passive increase in pulmonary pressure. In some patients, a superimposed active component caused by pulmonary arterial vasoconstriction and vascular remodeling may lead to a further increase in pulmonary arterial pressure. When present, PH is associated with a worse prognosis in patients with LHD. In addition to local abnormalities in nitric oxide and endothelin production, gene modifiers such as serotonin polymorphisms may be associated with the pathogenesis of PH in LHD. Optimizing heart failure regimens and corrective valve surgery represent the cornerstone of the treatment of PH in LHD. Recent studies suggest that sildenafil, a phosphodiesterase-5 inhibitor, is a promising agent in the treatment of PH in LHD. Unloading the left ventricle with circulatory support may also reverse severe PH in patients with end-stage heart failure allowing candidacy to heart transplantation.
View details for DOI 10.1016/j.pcad.2011.06.003
View details for Web of Science ID 000294880400009
View details for PubMedID 21875514
Disruption of the Apelin-APJ System Worsens Hypoxia-Induced Pulmonary Hypertension
ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY
2011; 31 (4): 814-U212
The G-protein-coupled receptor APJ and its ligand apelin are highly expressed in the pulmonary vasculature, but their function in this vascular bed is unclear. We hypothesized that disruption of apelin signaling would lead to worsening of the vascular remodeling associated with pulmonary hypertension (PH).We found that apelin-null mice developed more severe PH compared with wild-type mice when exposed to chronic hypoxia. Micro-computed tomography of the pulmonary arteries demonstrated significant pruning of the microvasculature in the apelin-null mice. Apelin-null mice had a significant reduction of serum nitrate levels. This was secondary to downregulation of endothelial nitric oxide synthase (eNOS), which was associated with reduced expression of Kruppel-like factor 2 (KLF2), a known regulator of eNOS expression. In vitro knockdown studies targeting apelin in human pulmonary artery endothelial cells demonstrated decreased eNOS and KLF2 expression, as well as impaired phosphorylation of AMP-activated kinase and eNOS. Moreover, serum apelin levels of patients with PH were significantly lower than those of controls.These data demonstrate that disruption of apelin signaling can exacerbate PH mediated by decreased activation of AMP-activated kinase and eNOS, and they identify this pathway as a potentially important therapeutic target for treatment of this refractory human disease.
View details for DOI 10.1161/ATVBAHA.110.219980
View details for Web of Science ID 000288437800017
View details for PubMedID 21233449
- Colonic ulceration as an unusual manifestation of vasculopathy in systemic sclerosis RHEUMATOLOGY 2011; 50 (3): 626-628
Drugs and toxins-associated pulmonary arterial hypertension: lessons learned and challenges ahead.
International journal of clinical practice. Supplement
Since the identification of the link between pulmonary arterial hypertension (PAH) and exposure to certain drugs and toxins nearly fifty years ago, the expanding landscape of available pharmaceuticals and illicit drugs is further fueling this association. While some causative agents in drugs and toxins associated PAH (D&T-APAH) have been identified, little is known about the exact biology and clinical implications of the disease. In this review, we discuss the historical evidence that links PAH with exposure to anorexinogens, cocaine, and methamphetamines and concentrate on what is known about potential pathogenesis, clinical manifestations, and current management. We conclude that future research should focus on studies looking at clinical outcome and susceptibility factors.
View details for DOI 10.1111/j.1742-1241.2010.02606.x
View details for PubMedID 21176010
Right ventricular failure: a novel era of targeted therapy.
Current heart failure reports
2010; 7 (4): 202-211
There now is strong evidence to recognize the pivotal role of the right ventricle (RV) in heart disease and to establish it as a unique and separate entity than the left ventricle (LV). Here, we summarize the differences between the two ventricles, the diagnosis of RV failure, and the management of acute and chronic RV failure. We review the indices derived by echocardiography used to measure RV function, and novel biomarkers that may play a role diagnosing and prognosticating in RV-specific disease. There are new novel therapies that specifically target the RV in disease. For example, phosphodiesterase type 5 inhibitors improve contractility of the hypertrophied RV while sparing the normal LV in pulmonary arterial hypertension. The metabolism of the hypertrophied RV is another area for therapeutic exploitation by metabolic modulation. We also suggest future potential molecular targets that may be unique to the RV because they are upregulated in RV hypertrophy greater than in LV hypertrophy.
View details for DOI 10.1007/s11897-010-0031-7
View details for PubMedID 20890792
Epoprostenol-associated pneumonitis: Diagnostic use of a T-cell proliferation assay
JOURNAL OF HEART AND LUNG TRANSPLANTATION
2010; 29 (9): 1071-1075
We describe a case of severe drug-induced interstitial pneumonitis in a woman with idiopathic pulmonary arterial hypertension receiving epoprostenol confirmed by a drug T-cell proliferation assay. Proliferation assays were completed in our patient and in a healthy control. Isolated T cells were incubated with CD3-depleted peripheral blood mononuclear cells and then stimulated to proliferate with (3)H-thymidine in the presence of epoprostenol, other prostanoid analogs, and controls. A significant (p < 0.001) T-cell proliferation response occurred in our patient in the presence of epoprostenol alone. There was a trend towards an increased T-cell response to treprostinil but this was statistically insignificant. There was no significant T-cell response to the diluent alone, normal saline, iloprost, or alprostadil. There was no significant proliferation to any drug in the healthy control. Hence, a drug T-cell proliferation assay confirmed that epoprostenol can rarely incite a profound inflammatory response in the pulmonary interstitium.
View details for DOI 10.1016/j.healun.2010.04.023
View details for Web of Science ID 000281494800016
ERG evaluation of daily, high-dose sildenafil usage
2009; 118 (3): 225-231
Sildenafil can cause transient, mild ERG changes in healthy individuals taking large single doses. Although the drug was originally intended for intermittent use in erectile dysfunction, it has now been approved for chronic use in subjects with pulmonary arterial hypertension (PAH). The purpose of our study is to investigate possible ERG changes in subjects using large doses of sildenafil on a chronic daily basis.We examined five subjects with PAH taking sildenafil daily for 1-4 years. Full-field electroretinogram (ERG), multifocal ERG (mfERG), and color testing were performed. Three of the subjects returned on a later date for challenge off and on the medication.On chronic daily sildenafil, color vision testing was normal, and ERG and mfERG amplitudes were normal; however, cone implicit times on drug were modestly lengthened. There were no consistent full-field ERG changes when off the drug, but the mfERG showed a small amplitude increase and implicit time decrease, which returned 1 h after re-dosing.There was a modest lengthening of cone implicit time on chronic daily doses of sildenafil and a hint that some of these changes may be reversible in the short term. It does not appear that chronic sildenafil usage at these dosage levels is seriously toxic or threatening to vision.
View details for DOI 10.1007/s10633-008-9148-3
View details for Web of Science ID 000266261000006
View details for PubMedID 18818963
Angina Associated With Left Main Coronary Artery Compression in Pulmonary Hypertension
JOURNAL OF HEART AND LUNG TRANSPLANTATION
2009; 28 (5): 527-530
Chest pain is a common complaint in patients with pulmonary arterial hypertension (PAH). Left main coronary artery (LMCA) compression by an enlarged pulmonary artery trunk (PAT) has been associated with angina, but appropriate diagnostic and treatment approaches remain poorly defined. We present two cases of angina caused by LMCA compression from an enlarged pulmonary artery, one of which also presented with new, severe left ventricular systolic dysfunction attributed to myocardial ischemia. Diagnosis of LMCA stenosis was made via coronary angiography followed by computed tomography-gated coronary angiography (CT-CA), which confirmed pulmonary artery enlargement as the source of extrinsic compression. Restoring LMCA patency with percutaneous intervention and/or aggressive treatment of pulmonary hypertension led to significant improvement in angina, cardiac function and quality of life. Given the negative impact on cardiac function, prompt diagnosis and treatment of extrinsic LMCA compression should be considered a priority.
View details for DOI 10.1016/j.healun.2008.12.008
View details for Web of Science ID 000266171400021
View details for PubMedID 19416787
Progressive dyspnea after CABG: Complication of retained epicardial pacing wires
ANNALS OF THORACIC SURGERY
2008; 86 (4): 1352-1354
We report a case of progressive dyspnea and recurrent pneumonia after uneventful coronary artery bypass graft surgery caused by migration of retained epicardial pacing wires into the right upper lobe of the lung. Removal of the wires by open thoracotomy resulted in significant improvement in dyspnea and near complete resolution of the bronchiectasis and consolidation.
View details for DOI 10.1016/j.athoracsur.2008.03.013
View details for Web of Science ID 000259848000044
View details for PubMedID 18805194
Effectiveness and cost effectiveness of thrombolysis in patients with acute pulmonary embolism
CURRENT OPINION IN PULMONARY MEDICINE
2008; 14 (5): 422-426
Acute pulmonary embolism is a common, life-threatening, cardiopulmonary disorder with a high mortality rate within the first 3 months of diagnosis. As prompt anticoagulation is the mainstay of therapy in patients with pulmonary embolism, the clinical utility and cost effectiveness of systemic thrombolysis is debated.Pulmonary embolism with cardiogenic shock and hypotension is characterized as 'massive' in nature and an accepted indication for thrombolysis, although catheter-directed embolectomy with or without local lytic therapy is preferred in centers with appropriate experience. Acute right ventricular dysfunction is a poor prognostic indicator in patients with pulmonary embolism. The most recent randomized controlled trial of systemic thrombolysis in patients with submassive pulmonary embolism and right ventricular dysfunction found that, compared with heparin alone, alteplase and heparin reduced the risk of clinical deterioration requiring treatment escalation, but did not reduce the risk of death. Subsequently, a formal cost effectiveness concluded that alteplase and heparin was slightly less effective and marginally more expensive than heparin alone in this patient population.Current evidence does not support the use of thrombolytic agents in most hemodynamically stable patients with right ventricular dysfunction. However, improved methods of risk stratification may help to identify subgroups of patients at high risk of death that might benefit from systemic thrombolysis.
View details for Web of Science ID 000258982100010
View details for PubMedID 18664972
- CT angiography of pulmonary artery aneurysms in Hughes-Stovin syndrome AMERICAN JOURNAL OF ROENTGENOLOGY 2005; 185 (2): 330-332
Surgical and interventional therapies for pulmonary arterial hypertension
SEMINARS IN RESPIRATORY AND CRITICAL CARE MEDICINE
2005; 26 (4): 417-428
Surgical and interventional therapies for pulmonary arterial hypertension (PAH) in appropriately selected patients have the potential to dramatically improve or, in some cases, cure PAH. These include atrial septostomy, a palliative procedure or bridge to transplantation in patients with refractory right heart failure, pulmonary thromboendarterectomy for pulmonary hypertension associated with chronic thromboembolic disease, and closure of congenital systemic-pulmonary shunts in patients with PAH but without significant pulmonary vascular disease. Lung transplantation should be considered for patients with all forms of PAH who demonstrate advanced or progressive disease.
View details for Web of Science ID 000231671900010
View details for PubMedID 16121319
Regulative response of the cranial neural tube after neural fold ablation: Spatiotemporal nature of neural crest regeneration and up-regulation of Slug
1995; 121 (12): 4103-4115
After unilateral ablation of the avian cranial neural folds, the remaining neuroepithelial cells are able to replace the missing neural crest population (Scherson et al., 1993). Here, we characterize the cellular and molecular nature of this regulative response by defining: (1) the time and location of neural crest cell production by the neuroepithelium; (2) rostrocaudal axial differences in the regulative response; and (3) the onset of expression of Slug, a transcription factor present in premigratory and migrating neural crest cells. Using DiI and HNK-1 antibody labeling techniques, we find that neural crest regeneration occurs only after apposition of the remaining neuroepithelium with the epidermis, suggesting that the developmental mechanism underlying regeneration of the neural crest may recapitulate initial generation of the neural crest. The regulative response occurs maximally at the 3-5 somite stage, and slowly declines thereafter. Surprisingly, there are profound regional differences in the regenerative ability. Whereas a robust regulation occurs in the caudal midbrain/hindbrain, the caudal forebrain/rostral midbrain regenerates neural crest to a much lesser extent. After neural fold removal in the hindbrain, regenerated neural crest cells migrate in a segmental pattern analogous to that seen in unablated embryos; a decrease in regulative response appears to occur with increasing depth of the ablation. Up-regulation of Slug appears to be an early response after ablation, with Slug transcripts detectable proximal to the ablated region 5-8 hours after surgery and prior to emergence of neural crest cells. Both bilateral and unilateral ablations yield substantial numbers of neural crest cells, though the former recover less rapidly and have greater deficits in neural crest-derived structures than the latter. These experiments demonstrate that the regulative ability of the cranial neuroepithelium to form neural crest depends on the time, location and extent of neural fold ablation.
View details for Web of Science ID A1995TM47800019
View details for PubMedID 8575311