All Publications

  • An Irregular Rhythm: What Is the Mechanism? JACC. Clinical electrophysiology Higuchi, S. n., Kumar, U. N., Badhwar, N. n., Tchou, P. n., Scheinman, M. M. 2020; 6 (9): 1205–11

    View details for DOI 10.1016/j.jacep.2020.08.006

    View details for PubMedID 32972562

  • Proceedings from Heart Rhythm Society's emerging technologies forum, Boston, MA, May 12, 2015. Heart rhythm Zeitler, E. P., Al-Khatib, S. M., Slotwiner, D., Kumar, U. N., Varosy, P., Van Wagoner, D. R., Marcus, G. M., Kusumoto, F. M., Blum, L. 2016; 13 (2): e39-49


    Physicians are in an excellent position to significantly contribute to medical device innovation, but the process of bringing an idea to the bedside is complex. To begin to address these perceived barriers, the Heart Rhythm Society convened a forum of stakeholders in medical device innovation in conjunction with the 2015 Heart Rhythm Society Annual Scientific Sessions. The forum facilitated open discussion on medical device innovation, including obstacles to physician involvement and possible solutions. This report is based on the themes that emerged. First, physician innovators must take an organized approach to identifying unmet clinical needs and potential solutions. Second, extensive funds, usually secured through solicitation for investment, are often required to achieve meaningful progress, developing an idea into a device. Third, planning for regulatory requirements of the US Food and Drug Administration and Centers for Medicare & Medicaid Services is essential. In addition to these issues, intellectual property and overall trends in health care, including international markets, are critically relevant considerations for the physician innovator. Importantly, there are a number of ways in which professional societies can assist physician innovators to navigate the complex medical device innovation landscape, bring clinically meaningful devices to market more quickly, and ultimately improve patient care. These efforts include facilitating interaction between potential collaborators through scientific meetings and other gatherings; collecting, evaluating, and disseminating state-of-the-art scientific information; and representing the interests of members in interactions with regulators and policymakers.

    View details for DOI 10.1016/j.hrthm.2015.12.001

    View details for PubMedID 26801401

    View details for PubMedCentralID PMC4724379

  • Needs-Based Innovation in Cardiovascular Medicine The Stanford Biodesign Process JACC. Basic to translational science Schwartz, J. G., Kumar, U. N., Azagury, D. E., Brinton, T. J., Yock, P. G. 2016; 1 (6): 541-547
  • Outcomes from a Postgraduate Biomedical Technology Innovation Training Program: The First 12 Years of Stanford Biodesign ANNALS OF BIOMEDICAL ENGINEERING Brinton, T. J., Kurihara, C. Q., Camarillo, D. B., Pietzsch, J. B., Gorodsky, J., Zenios, S. A., Doshi, R., Shen, C., Kumar, U. N., Mairal, A., Watkins, J., Popp, R. L., Wang, P. J., Makower, J., Krummel, T. M., Yock, P. G. 2013; 41 (9): 1803-1810


    The Stanford Biodesign Program began in 2001 with a mission of helping to train leaders in biomedical technology innovation. A key feature of the program is a full-time postgraduate fellowship where multidisciplinary teams undergo a process of sourcing clinical needs, inventing solutions and planning for implementation of a business strategy. The program places a priority on needs identification, a formal process of selecting, researching and characterizing needs before beginning the process of inventing. Fellows and students from the program have gone on to careers that emphasize technology innovation across industry and academia. Biodesign trainees have started 26 companies within the program that have raised over $200 million and led to the creation of over 500 new jobs. More importantly, although most of these technologies are still at a very early stage, several projects have received regulatory approval and so far more than 150,000 patients have been treated by technologies invented by our trainees. This paper reviews the initial outcomes of the program and discusses lessons learned and future directions in terms of training priorities.

    View details for DOI 10.1007/s10439-013-0761-2

    View details for Web of Science ID 000323736800002

    View details for PubMedID 23404074

  • Diagnostic utility of a novel leadless arrhythmia monitoring device. American journal of cardiology Turakhia, M. P., Hoang, D. D., Zimetbaum, P., Miller, J. D., Froelicher, V. F., Kumar, U. N., Xu, X., Yang, F., Heidenreich, P. A. 2013; 112 (4): 520-524


    Although extending the duration of ambulatory electrocardiographic monitoring beyond 24 to 48 hours can improve the detection of arrhythmias, lead-based (Holter) monitors might be limited by patient compliance and other factors. We, therefore, evaluated compliance, analyzable signal time, interval to arrhythmia detection, and diagnostic yield of the Zio Patch, a novel leadless, electrocardiographic monitoring device in 26,751 consecutive patients. The mean wear time was 7.6 ± 3.6 days, and the median analyzable time was 99% of the total wear time. Among the patients with detected arrhythmias (60.3% of all patients), 29.9% had their first arrhythmia and 51.1% had their first symptom-triggered arrhythmia occur after the initial 48-hour period. Compared with the first 48 hours of monitoring, the overall diagnostic yield was greater when data from the entire Zio Patch wear duration were included for any arrhythmia (62.2% vs 43.9%, p <0.0001) and for any symptomatic arrhythmia (9.7% vs 4.4%, p <0.0001). For paroxysmal atrial fibrillation (AF), the mean interval to the first detection of AF was inversely proportional to the total AF burden, with an increasing proportion occurring after 48 hours (11.2%, 10.5%, 20.8%, and 38.0% for an AF burden of 51% to 75%, 26% to 50%, 1% to 25%, and <1%, respectively). In conclusion, extended monitoring with the Zio Patch for ≤14 days is feasible, with high patient compliance, a high analyzable signal time, and an incremental diagnostic yield beyond 48 hours for all arrhythmia types. These findings could have significant implications for device selection, monitoring duration, and care pathways for arrhythmia evaluation and AF surveillance.

    View details for DOI 10.1016/j.amjcard.2013.04.017

    View details for PubMedID 23672988

  • Frequency of Atrial Flutter After Adult Lung Transplantation AMERICAN JOURNAL OF CARDIOLOGY Azadani, P. N., Kumar, U. N., Yang, Y., Scheinman, M. M., Hoopes, C. W., Marcus, G. M., Rifkin, C., Olgin, J. E., Lee, B. K. 2011; 107 (6): 922-926


    Lung transplantation, which involves an anastomosis of the graft to the native left atrium, may increase the risk of left-side atrial flutter (AFL). Our aim was to evaluate the incidence, predisposing conditions, and course of AFL after lung transplantation in adults. Two hundred sixty-nine consecutive patients who underwent lung transplantation were studied retrospectively. All patients received a preoperative echocardiogram and postoperative electrocardiographic monitoring. All 12-lead electrocardiograms were reviewed. Typical or atypical AFL was diagnosed by 2 independent reviewers based on accepted criteria. Predictors of AFL were investigated separately using univariate and multivariate logistic regression analyses. AFL occurred in 35 of 269 patients (13%) over a mean of 12 days after transplantation. All patients who developed AFL had no previous atrial arrhythmia. Of these 35 patients, 24 (68.6%) had atypical AFL by electrocardiographic criteria. In multivariate logistic regression analysis, patients with idiopathic pulmonary fibrosis (IPF) were 2.9 times more likely to have AFL than those patients with lung transplant without IPF (p = 0.009). Other independent risk factors for AFL were advanced age and preoperative left atrial enlargement. Only 3 of 35 patients (8.6%) with AFL had persistent atrial arrhythmia and needed electrophysiologic study and ablation. In conclusion, AFL is common soon after lung transplantation. Those with IPF, advanced age, or left atrial enlargement are at increased risk. In most cases, AFL is a self-limited arrhythmia that resolves spontaneously with no need for ablation.

    View details for DOI 10.1016/j.amjcard.2010.10.076

    View details for Web of Science ID 000288825300020

    View details for PubMedID 21247524

  • Response to letter regarding article, "Reduced Ventricular Volumes and Improved Systolic Function With Cardiac Resynchronization Therapy: A Randomized Trial Comparing Simultaneous Biventricular Pacing, Sequential Biventricular Pacing, and Left Ventricular Pacing" CIRCULATION Rao, R. K., Viloria, E., Foster, E., Kumar, U. N., Schafer, J., De Lurgio, D. 2008; 117 (3): E15
  • Reduced ventricular volumes and improved systolic function with cardiac resynchronization therapy - A randomized trial comparing simultaneous biventricular pacing, sequential biventricular pacing, and left ventricular pacing CIRCULATION Rao, R. K., Kumar, U. N., Schafer, J., Viloria, E., De Lurgio, D., Foster, E. 2007; 115 (16): 2136–44


    Cardiac resynchronization therapy has emerged as an important therapy for advanced systolic heart failure. Among available cardiac resynchronization therapy pacing modes that restore ventricular synchrony, it is uncertain whether simultaneous biventricular (BiV), sequential BiV, or left ventricular (LV) pacing is superior. The Device Evaluation of CONTAK RENEWAL 2 and EASYTRAK 2: Assessment of Safety and Effectiveness in Heart Failure (DECREASE-HF) trial is the first randomized trial comparing these 3 cardiac resynchronization therapy modalities.The DECREASE-HF Trial is a multicenter trial in which 306 patients with New York Heart Association class III or IV heart failure, an LV ejection fraction < or = 35%, and a QRS duration > or = 150 ms were randomized to simultaneous BiV, sequential BiV, or LV pacing. LV volumes and systolic and diastolic function were assessed with echocardiography at baseline, 3 months, and 6 months. All groups had a significant reduction in LV end-systolic and end-diastolic dimensions (P<0.001). The simultaneous BiV pacing group had the greatest reduction in LV end-systolic dimension (P=0.007). Stroke volume (P<0.001) and LV ejection fraction (P<0.001) improved in all groups with no difference across groups.Compared with LV pacing, simultaneous BiV pacing was associated with a trend toward greater improvement in LV size. There is little difference between simultaneous BiV pacing and sequential BiV pacing as programmed in this trial.

    View details for DOI 10.1161/CIRCULATIONAHA.106.634444

    View details for Web of Science ID 000245919600009

    View details for PubMedID 17420340

  • Echocardiographic changes after cardiac resynchronization therapy are not associated with changes in clinical measures Rao, R., Kumar, U. N., Schafer, J., DeLurgio, D. B., Foster, E. LIPPINCOTT WILLIAMS & WILKINS. 2006: 615–16
  • The 12-lead electrocardiogram in supraventricular tachycardia. Cardiology clinics Kumar, U. N., Rao, R. K., Scheinman, M. M. 2006; 24 (3): 427-37, ix


    The 12-lead electrocardiogram (ECG) is an invaluable tool for the diagnosis of supraventricular tachycardia (SVT). Most forms of SVT can be distinguished with a high degree of certainty based on specific ECG characteristics by using a systematic, stepwise approach. This article provides a general framework with which to approach an ECG during SVT by describing the salient characteristics, ECG findings, and underlying electroanatomical relationships of each specific type of SVT encountered in adults. It concludes by providing a systematic algorithm for diagnosing SVT based on the findings of the 12-lead ECG.

    View details for DOI 10.1016/j.ccl.2006.04.004

    View details for PubMedID 16939834

  • Ventricular resynchronization: a promising therapy for heart failure. The American journal of geriatric cardiology Kumar, U. N., Saxon, L. A. 2002; 12 (1): 41-8


    Primarily a disease of the elderly, heart failure continues to be an ever-increasing health care problem given the growth in the number of individuals over age 65. Although there have been many advances in the pharmacologic management of heart failure, there continues to be a significant number of patients with persistent symptoms despite maximal therapy and it is likely that this group of patients will only continue to increase in number. Given this, significant research has gone into exploring new modalities, such as device therapies, to treat heart failure. Of these, ventricular resynchronization has emerged as one of the most promising. This review will examine the most important aspects of ventricular resynchronization therapy including: the significance of ventricular dyssynchrony, the role of traditional pacemakers, the effects on contractile function and reverse remodeling, and the currently accepted indications for resynchronization devices. Additionally, various aspects of completed and ongoing trials will be discussed.

    View details for DOI 10.1111/j.1076-7460.2003.01756.x

    View details for PubMedID 12502915

  • Effects of long-term biventricular stimulation for resynchronization on echocardiographic measures of remodeling. Circulation Saxon, L. A., De Marco, T., Schafer, J., Chatterjee, K., Kumar, U. N., Foster, E. 2002; 105 (11): 1304-10


    Long-term ventricular resynchronization therapy improves symptom status. Changes in left ventricular remodeling have not been adequately evaluated.Fifty-three patients with systolic heart failure and bundle-branch block underwent implantation of biventricular stimulation (BVS) devices as part of a randomized trial. Echocardiograms were acquired at randomization and at 6-week intervals until completion of 12 weeks of continuous BVS. There were no changes in heart rate or QRS duration after 12 weeks of BVS. Serum norepinephrine values did not change with BVS. After 12 weeks of BVS, left atrial volume decreased. Left ventricular end-systolic and end-diastolic dimensions and left ventricular end-systolic volume also decreased after 12 weeks of BVS. Sphericity index did not change. Measures of systolic function, including left ventricular outflow tract and aortic velocity time integral and myocardial performance index, improved.Long-term resynchronization therapy results in atrial and ventricular reverse remodeling and improved hemodynamics.

    View details for DOI 10.1161/hc1102.105730

    View details for PubMedID 11901040

  • Adjuvant high-dose interferon alfa-2b in patients with high-risk melanoma. Cancer journal (Sudbury, Mass.) Jonasch, E., Kumar, U. N., Linette, G. P., Hodi, F. S., Soiffer, R. J., Ryan, B. F., Sober, A. J., Mihm, M. C., Tsao, H., Langley, R. G., Cosimi, B. A., Gadd, M. A., Tanabe, K. K., Souba, W., Haynes, H. A., Barnhill, R., Osteen, R., Haluska, F. G. 2000; 6 (3): 139-45


    We performed an analysis of toxicity and survival in stage III melanoma patients receiving adjuvant interferon alfa-2b (IFN). This was a retrospective single-arm analysis of 40 patients with stage III melanoma who received (IFN) administered at maximum tolerated doses of 20 mU/m2/day intravenously (i.v.) for 1 month and 10 mU/m2 three times per week subcutaneously (s.c.) for 48 weeks. Toxicity in our series is comparable to that experienced in the Eastern Cooperative Oncology Group (ECOG) 1684 trial, except for higher rates of dose-limiting myelosuppression and hepatotoxicity. All 40 patients experienced constitutional symptoms, but only 14/40 (35%) experienced grade 3 to 4 symptoms. Of the 40 patients, 36 (90%) experienced neurologic symptoms, but only seven (17.5%) experienced grade 3 to 4 neurotoxicity. Two patients stopped treatment because of severe psychiatric symptoms; one patient attempted suicide, and a psychosis developed in another. Thirty-nine (97.5%) patients experienced myelosuppression; 31 (77.5%) developing grade 3 to 4 myelosuppression. Hepatotoxicity was evident in 39 (97.5%) patients, and 26 (65%) experienced grade 3 to 4 hepatotoxicity. Three patients (7.5%) experienced mild renal toxicity. At a median follow-up of 27 months from initiation of therapy, there have been 19 relapses (47.5% disease-free survival [DFS]) and 10 deaths (75% OS) resulting from progression of disease. The DFS compares with the treatment arm in ECOG 1684 at 27 months, but overall survival is higher in our series of patients at the same time point. In a single program setting, IFN can be administered with similar side effects and outcome profiles seen in multi-institutional studies. Modifications in the induction regimen resulted in notably higher hematologic and hepatic toxicities but did not preclude administering further therapy and did not result in increased attrition rate among patients: only nine patients (22.5%) had their treatment stopped as a result of IFN-related toxicity. In comparison, 26% of patients had to have their treatment discontinued because of toxicity in ECOG 1684.

    View details for PubMedID 10882328