- Cardiovascular Disease
- Internal Medicine
Clinical Scholar, Medicine
Honors & Awards
NIH F32 Ruth Kirschstein National Research Service Award Grant, National Institute of Health (NIH) (2019)
Alpha Omega Alpha (AOA) Member, Alpha Omega Alpha (AOA) (2014)
Myron F. Kanter and Lawrence J. Kanter Endowment Fund Award, Myron F. Kanter and Lawrence J. Kanter Foundation (2014)
Sarnoff Cardiovascular Research Foundation Fellowship, Sarnoff Cardiovascular Foundation (2012-2013)
Irwin H. Lepow Research Award, Irwin H. Lepow Research Foundation (2011)
American Federation of Aging Research (AFAR) Grant Recipient, American Federation of Aging Research (AFAR) (2010)
Boards, Advisory Committees, Professional Organizations
Cardio-Oncology Subcommittee Member, American Heart Association (AHA) (2019 - Present)
Member, American College of Cardiology Cardio-Oncology - California Chapter (2020 - Present)
Member, Society of Cardiovascular Computed Tomography (SCCT) (2019 - Present)
Member, American Society of Echocardiography (2019 - Present)
Fellowship, Stanford University, Cardiology
Residency, Stanford University, Internal Medicine (2017)
Doctor of Medicine, Case Western Reserve University School of Medicine, Medicine (2014)
Bachelor of Science, Massachusetts Institute of Technology (MIT), Biological Engineering (2009)
Cardiovascular Complications in Patients with COVID-19: Consequences of Viral Toxicities and Host Immune Response
Curr Cardiol Rep
2020; 22 (5)
View details for DOI 10.1007/s11886-020-01292-3
Low Wall Shear Stress Is Associated with Saphenous Vein Graft Stenosis in Patients with Coronary Artery Bypass Grafting.
Journal of cardiovascular translational research
Biomechanical forces may play a key role in saphenous vein graft (SVG) disease after coronary artery bypass graft (CABG) surgery. Computed tomography angiography (CTA) of 430 post-CABG patients were evaluated and 15 patients were identified with both stenosed and healthy SVGs for paired analysis. The stenosis was virtually removed, and detailed 3D models were reconstructed to perform patient-specific computational fluid dynamic (CFD) simulations. Models were processed to compute anatomic parameters, and hemodynamic parameters such as local and vessel-averaged wall shear stress (WSS), normalized WSS (WSS*), low shear area (LSA), oscillatory shear index (OSI), and flow rate. WSS* was significantly lower in pre-diseased SVG segments compared to corresponding control segments without disease (1.22 vs. 1.73, p = 0.012) and the area under the ROC curve was 0.71. No differences were observed in vessel-averaged anatomic or hemodynamic parameters between pre-stenosed and control whole SVGs. There are currently no clinically available tools to predict SVG failure post-CABG. CFD modeling has the potential to identify high-risk CABG patients who may benefit from more aggressive medical therapy and closer surveillance. Graphical Abstract.
View details for DOI 10.1007/s12265-020-09982-7
View details for PubMedID 32240496
Cardiovascular Risks in Patients with COVID-19: Potential Mechanisms and Areas of Uncertainty.
Current cardiology reports
2020; 22 (5): 34
COronaVirus Disease 2019 (COVID-19) has spread at unprecedented speed and scale into a global pandemic with cardiovascular risk factors and complications emerging as important disease modifiers. We aim to review available clinical and biomedical literature on cardiovascular risks of COVID-19.SARS-CoV2, the virus responsible for COVID-19, enters the cell via ACE2 expressed in select organs. Emerging epidemiological evidence suggest cardiovascular risk factors are associated with increased disease severity and mortality in COVID-19 patients. Patients with a more severe form of COVID-19 are also more likely to develop cardiac complications such as myocardial injury and arrhythmia. The true incidence of and mechanism underlying these events remain elusive. Cardiovascular diseases appear intricately linked with COVID-19, with cardiac complications contributing to the elevated morbidity/mortality of COVID-19. Robust epidemiologic and biologic studies are urgently needed to better understand the mechanism underlying these associations to develop better therapies.
View details for DOI 10.1007/s11886-020-01293-2
View details for PubMedID 32350632
NOVEL ALPHA-ACTININ 2 MUTATIONS ARE ASSOCIATED WITH CARDIOMYOPATHY AND HYPERTROPHY IN HUMAN CARDIAC TISSUE AND IPSC-DERIVED CARDIOMYOCYTES
ELSEVIER SCIENCE INC. 2019: 1027
View details for Web of Science ID 000460565901040
- Computational Fluid Dynamics (BypassCFD) Trumps Anatomic Predictors of Saphenous Vein Graft Failure in CABG Patients American Heart Association 2018
Sinoatrial node toxicity after stereotactic ablative radiation therapy to lung tumors.
Practical radiation oncology
Stereotactic ablative radiation therapy (SABR) is an established treatment for selected lung tumors. Sinoatrial node (SAN) toxicity after thoracic SABR has not been reported in the literature. We sought to understand the risk of SAN toxicity owing to incidental dose to the SAN from SABR.We conducted a retrospective review of patients with early-stage lung cancer or limited pulmonary metastases who underwent thoracic SABR to a right-sided central lung tumor (within 2 cm of the mainstem bronchus or other mediastinal structures) between January 2008 and December 2014, analyzed a subset whose treatment imparted dose to the SAN exceeding 10% of the prescription dose, and examined patient and treatment dosimetric characteristics. Mean follow-up interval was 28 months. Time to toxicity was defined from start of SABR.Of 47 patients with central tumors in the right lung treated with SABR reviewed, 13 met our study criteria. A contouring atlas of regional cardiac anatomy was created. One patient treated with SABR for non-small cell lung cancer at the right hilum developed symptomatic sick sinus syndrome, requiring pacemaker placement 6 months after treatment. Her acute presentation and short interval between SABR and onset of symptoms suggest that SAN toxicity was likely due to radiation-induced injury. Both her age and mean dose to her SAN were the third highest in our cohort. She remained free from cancer progression at 24 months' follow-up. Twelve additional patients who received significant dose to the SAN from SABR did not develop toxicity.While uncommon, SAN toxicity from SABR to right-sided central thoracic tumors should be recognized and followed in future studies.
View details for PubMedID 28669706
ACTN2 Mutations Are Associated With Cardiomyopathy and Cardiomyocyte Hypertrophy
LIPPINCOTT WILLIAMS & WILKINS. 2016
View details for Web of Science ID 000396815606012
Glucocorticoids enhance muscle endurance and ameliorate Duchenne muscular dystrophy through a defined metabolic program.
Proceedings of the National Academy of Sciences of the United States of America
2015; 112 (49): E6780–9
Classic physiology studies dating to the 1930s demonstrate that moderate or transient glucocorticoid (GC) exposure improves muscle performance. The ergogenic properties of GCs are further evidenced by their surreptitious use as doping agents by endurance athletes and poorly understood efficacy in Duchenne muscular dystrophy (DMD), a genetic muscle-wasting disease. A defined molecular basis underlying these performance-enhancing properties of GCs in skeletal muscle remains obscure. Here, we demonstrate that ergogenic effects of GCs are mediated by direct induction of the metabolic transcription factor KLF15, defining a downstream pathway distinct from that resulting in GC-related muscle atrophy. Furthermore, we establish that KLF15 deficiency exacerbates dystrophic severity and muscle GC-KLF15 signaling mediates salutary therapeutic effects in the mdx mouse model of DMD. Thus, although glucocorticoid receptor (GR)-mediated transactivation is often associated with muscle atrophy and other adverse effects of pharmacologic GC administration, our data define a distinct GR-induced gene regulatory pathway that contributes to therapeutic effects of GCs in DMD through proergogenic metabolic programming.
View details for DOI 10.1073/pnas.1512968112
View details for PubMedID 26598680
View details for PubMedCentralID PMC4679037
miR-222 is necessary for exercise-induced cardiac growth and protects against pathological cardiac remodeling.
2015; 21 (4): 584–95
Exercise induces physiological cardiac growth and protects the heart against pathological remodeling. Recent work suggests exercise also enhances the heart's capacity for repair, which could be important for regenerative therapies. While microRNAs are important in certain cardiac pathologies, less is known about their functional roles in exercise-induced cardiac phenotypes. We profiled cardiac microRNA expression in two distinct models of exercise and found microRNA-222 (miR-222) was upregulated in both. Downstream miR-222 targets modulating cardiomyocyte phenotypes were identified, including HIPK1 and HMBOX1. Inhibition of miR-222 in vivo completely blocked cardiac and cardiomyocyte growth in response to exercise while reducing markers of cardiomyocyte proliferation. Importantly, mice with inducible cardiomyocyte miR-222 expression were resistant to adverse cardiac remodeling and dysfunction after ischemic injury. These studies implicate miR-222 as necessary for exercise-induced cardiomyocyte growth and proliferation in the adult mammalian heart and show that it is sufficient to protect the heart against adverse remodeling.
View details for DOI 10.1016/j.cmet.2015.02.014
View details for PubMedID 25863248
View details for PubMedCentralID PMC4393846
Kruppel-like factor 15 is a critical regulator of cardiac lipid metabolism.
The Journal of biological chemistry
2014; 289 (9): 5914–24
The mammalian heart, the body's largest energy consumer, has evolved robust mechanisms to tightly couple fuel supply with energy demand across a wide range of physiologic and pathophysiologic states, yet, when compared with other organs, relatively little is known about the molecular machinery that directly governs metabolic plasticity in the heart. Although previous studies have defined Kruppel-like factor 15 (KLF15) as a transcriptional repressor of pathologic cardiac hypertrophy, a direct role for the KLF family in cardiac metabolism has not been previously established. We show in human heart samples that KLF15 is induced after birth and reduced in heart failure, a myocardial expression pattern that parallels reliance on lipid oxidation. Isolated working heart studies and unbiased transcriptomic profiling in Klf15-deficient hearts demonstrate that KLF15 is an essential regulator of lipid flux and metabolic homeostasis in the adult myocardium. An important mechanism by which KLF15 regulates its direct transcriptional targets is via interaction with p300 and recruitment of this critical co-activator to promoters. This study establishes KLF15 as a key regulator of myocardial lipid utilization and is the first to implicate the KLF transcription factor family in cardiac metabolism.
View details for DOI 10.1074/jbc.M113.531384
View details for PubMedID 24407292
View details for PubMedCentralID PMC3937660
Kruppel-like factor 15 regulates skeletal muscle lipid flux and exercise adaptation.
Proceedings of the National Academy of Sciences of the United States of America
2012; 109 (17): 6739–44
The ability of skeletal muscle to enhance lipid utilization during exercise is a form of metabolic plasticity essential for survival. Conversely, metabolic inflexibility in muscle can cause organ dysfunction and disease. Although the transcription factor Kruppel-like factor 15 (KLF15) is an important regulator of glucose and amino acid metabolism, its endogenous role in lipid homeostasis and muscle physiology is unknown. Here we demonstrate that KLF15 is essential for skeletal muscle lipid utilization and physiologic performance. KLF15 directly regulates a broad transcriptional program spanning all major segments of the lipid-flux pathway in muscle. Consequently, Klf15-deficient mice have abnormal lipid and energy flux, excessive reliance on carbohydrate fuels, exaggerated muscle fatigue, and impaired endurance exercise capacity. Elucidation of this heretofore unrecognized role for KLF15 now implicates this factor as a central component of the transcriptional circuitry that coordinates physiologic flux of all three basic cellular nutrients: glucose, amino acids, and lipids.
View details for DOI 10.1073/pnas.1121060109
View details for PubMedID 22493257
View details for PubMedCentralID PMC3340075
Elevated fibroblast growth factor-2 increases tumor necrosis factor-alpha induced endothelial cell death in high glucose.
Journal of cellular physiology
2008; 217 (1): 86–92
Glucose and tumor necrosis factor-alpha (TNFalpha) concentrations are elevated in diabetes. Both of these factors correlate with diabetic vasculopathy and endothelial cell apoptosis, yet their combined effects have not been measured. We have previously shown that the angiogenic growth factor fibroblast growth factor-2 (FGF-2), which is generally protective against endothelial cell death, is similarly elevated in high glucose conditions. We therefore investigated the effect of TNFalpha on endothelial cell death under normal and elevated glucose conditions, with a particular focus on FGF-2. Porcine aortic endothelial cells were cultured in 5 and 30 mM glucose and stimulated with TNFalpha, together with FGF-2 or a neutralizing FGF-2 antibody. Cell death was measured via cell counts or an annexin apoptotic assay, and cell cycle phase was determined by propidium iodide labeling. TNFalpha-induced endothelial cell death increased for cells in high glucose, and cell death was enhanced with increasing FGF-2 exposure and negated by a neutralizing FGF-2 antibody. Endothelial cells were most susceptible to TNFalpha-induced cell death when stimulated with FGF-2 18 h prior to TNFalpha, corresponding to cell entry into S phase of the proliferative cycle. The FGF-2 associated increase in TNFalpha-induced cell death was negated by blocking cell entry into S phase. Endothelial cell release of FGF-2 in high glucose leads to cell cycle progression, which makes cells more susceptible to TNFalpha-induced cell death. These data suggest that growth factor outcomes in high glucose depend on secondary mediators such as cytokines and stimulation cell cycle timing.
View details for DOI 10.1002/jcp.21476
View details for PubMedID 18446810
View details for PubMedCentralID PMC2838244
A porous photocurable elastomer for cell encapsulation and culture.
2007; 28 (32): 4826–35
Encapsulating cells within a polymer matrix creates a three-dimensional (3D) scaffold that may more accurately represent the native microenvironment and cell organization. Here we report a porous scaffold prepared from a photocurable elastomer, poly(glycerolco-sebacate)-acrylate (PGSA). The scaffold porosity, swelling, mass loss, toxicity and mechanical properties, suggest that porous PGSA could be used to support the growth and differentiation of encapsulated cells. Neuroblastoma (NB) and human embryonic stem cells (hESCs) were encapsulated into the matrix and found to adhere to the material and interact with each other within 24h. After 7 days, encapsulated NB cells were found to grow, and form matrix fibrils and tissue. Undifferentiated hESCs proliferated and differentiated in the PGSA scaffold. In vivo experiments showed that both porous scaffolds have similar biocompatibility profiles as non-porous PGSA, but porous PGSA promotes tissue ingrowth, as compared to non-porous PGSA. We therefore propose that porous PGSA scaffolds can provide a logistical template for 3D growth of cells and tissue engineering.
View details for DOI 10.1016/j.biomaterials.2007.07.039
View details for PubMedID 17692371