Sumanth Kidambi

All Publications

• Ex Vivo Modeling of Atrioventricular Valve Mechanics in Single Ventricle Physiology. Annals of biomedical engineering Moye, S. C., Kidambi, S., Lee, J. Y., Cowles, T. H., Gilligan-Steinberg, S. D., Bryan, A. Y., Wilkerson, R., Woo, Y. J., Ma, M. R. 2023

  Abstract

  Single ventricle physiology (SVP) is used to describe any congenital heart lesion that is unable to support independent pulmonary and systemic circulations. Current treatment strategies rely on a series of palliation surgeries that culminate in the Fontan physiology, which relies on the single functioning ventricle to provide systemic circulation while passively routing venous return through the pulmonary circulation. Despite significant reductions in early mortality, the presence of atrioventricular valve (AVV) regurgitation is a key predictor of heart failure in these patients. We sought to evaluate the biomechanical changes associated with the AVV in SVP physiologies. Left and right ventricles were sutured onto patient-derived 3D-printed mounts and mounted into an ex vivo systemic heart simulator capable of reproducing Norwood, Glenn, Fontan and Late Fontan physiologies. We found that the tricuspid anterior leaflet experienced elevated maximum force, average force, and maximum yank compared to the posterior and septal leaflets. Between physiologies, maximum yank was greatest in the Norwood physiology relative to the Glenn, Fontan, and Late Fontan physiologies. These contrasting trends suggest that long- and short-term mechanics of AVV failure in single ventricle differ and that AVV interventions should account for asymmetries in force profiles between leaflets and physiologies.

  View details for DOI 10.1007/s10439-023-03178-1

  View details for PubMedID 36966247

  View details for PubMedCentralID 5371563

• Force Profiles of Single Ventricle Atrioventricular Leaflets in Response to Annular Dilation and Leaflet Tethering. Seminars in thoracic and cardiovascular surgery Kidambi, S., Moye, S. C., Lee, J., Cowles, T. H., Strong, E. B., Wilkerson, R., Paulsen, M. J., Woo, Y. J., Ma, M. R. 2022

  Abstract

  We sought to understand how leaflet forces change in response to annular dilation and leaflet tethering in single ventricle physiology. Explanted fetal bovine tricuspid valves were sutured onto image-derived annuli and ventricular mounts. Control valves (CV) were secured to a size-matched HLHS-type annulus and compared to: 1) normal tricuspid valves (NTV) secured to a size-matched saddle-shaped annulus, 2) HLHS-type annulus with leaflet tethering (LT), 3) HLHS-type annulus with annular dilation (DIL), or 5) a combined disease model with both dilation and tethering (DIS). The specimens were tested in a systemic heart simulator at various SVPs. Leaflet forces were measured using optical strain sensors sutured to each leaflet edge. Average force in the anterior leaflet was 43.2% lower in CV compared to NTV (p<0.001). LT resulted in a 6.6% increase in average forces on the anterior leaflet (p=0.04), 10.7% increase on the posterior leaflet (p=0.03), and 14.1% increase on the septal leaflet (p<0.001). In DIL, average septal leaflet forces increased relative to the control valves by 42.2% (p=0.01). In DIS, average leaflet forces increased by 54.8% in the anterior leaflet (p<0.001), 37.6% in the posterior leaflet (p=0.03), and 79.9% in the septal leaflet (p<0.001). The anterior leaflet experiences the highest forces in the normal tricuspid annulus under SVP conditions. Annular dilation resulted in an increase in forces on the septal leaflet and leaflet tethering resulted in an increase in forces across all 3 leaflets. Annular dilation and leaflet tethering combined resulted in the largest increase in leaflet forces across all 3 leaflets.

  View details for DOI 10.1053/j.semtcvs.2022.09.012

  View details for PubMedID 36455710

• Evaluating predicted heart mass in adolescent heart transplantation. The Journal of heart and lung transplantation : the official publication of the International Society for Heart Transplantation Lee, J. Y., Zawadzki, R. S., Kidambi, S., Rosenthal, D. N., Dykes, J. C., Nasirov, T., Ma, M. 2022

  Abstract

  BACKGROUND: Predicted Heart Mass (PHM) has emerged as an attractive size matching metric in adult cardiac transplantation. However, since PHM was derived from a healthy adult cohort, its generalizability to the pediatric population is unclear. We hypothesize that PHM can be extended to older adolescents, and potentially broaden the donor pool available to this group.METHODS: The United Network for Organ Sharing database was retrospectively analyzed for patients aged 13 to 18 undergoing heart transplantation. Recipients were divided into quintiles (Q1-Q5) based on donor-to-recipient predicted heart mass ratios (PHMR). Primary end-point was graft survival at 5 years.RESULTS: Two thousand sixty-one adolescent heart transplant recipients between January 1994 and September 2019 were retrospectively analyzed. The median PHMR's for each quintile was 0.84 (0.59-0.92), 0.97 (0.92-1.02), 1.08 (1.02-1.14), 1.21 (1.14-1.30), and 1.44 (1.30-2.31). Kaplan-Meier survival curves demonstrated comparable survival across all quintiles of PHMR (p=0.9). Multivariate Cox regression showed no significant difference in graft failure of the outer quintiles when compared to the middle quintile (Q1: 1.04 HR, p=0.80; Q2: 1.02 HR, p=0.89; Q4: 1.19 HR, p=0.28; Q5: 1.02 HR, p=0.89). Significant covariates included transplant year (HR: 0.95, p < 0.0001), serum bilirubin (HR: 1.04, p=0.0004), ECMO at transplantation (HR: 2.85, p < 0.0001), and underlying diagnosis of dilated cardiomyopathy (vs congenital heart disease, HR: 0.66, p=0.0004).CONCLUSIONS: Matching by PHM is not associated with survival or risk in adolescent heart transplant recipients. Our results underscore the ongoing need to develop an improved size-matching method in pediatric heart transplantation.

  View details for DOI 10.1016/j.healun.2022.08.027

  View details for PubMedID 36210265

• Weight Matching in Infant Heart Transplantation: A National Registry Analysis. The Annals of thoracic surgery Lee, J. Y., Kidambi, S., Zawadzki, R. S., Rosenthal, D. N., Dykes, J. C., Nasirov, T., Ma, M. 2022

  Abstract

  BACKGROUND: Infants account for a significant proportion of pediatric heart transplants, but also suffer from a high waitlist mortality. Donor oversizing by weight-based criteria is common practice in transplantation and is prevalent in this group. We sought to analyze the impact of oversizing on outcomes in infants.METHODS: Infant heart transplantations reported to the United Network for Organ Sharing from 01/1994 to 09/2019 were retrospectively analyzed. 2384 heart transplantation recipients were divided into quintiles (Q1-Q5) based on donor-to-recipient weight ratios (DRWR). Multivariate Cox regression was used to estimate the effect of DRWR. The primary endpoint of graft survival at one year.RESULTS: The median DRWR for each quintile was 0.90 (0.37 to 1.04), 1.17 (1.04 to 1.29), 1.43 (1.29 to 1.57), 1.74 (1.58 to 1.97), and 2.28 (1.97 to 5.00). Pairwise comparisons showed improved survival for Q3 and Q4 over each of the bottom two quintiles and the top quintile, respectively. Regression analyses found that Q3 and Q4 were protective against graft failure when compared to the bottom two quintiles, respectively. There was no difference in hazard amongst the top three quintiles. Significant covariates included primary diagnosis, ischemic time, serum bilirubin, transplant year, mechanical ventilation at transplantation, extracorporeal membrane oxygenation at transplantation. Gender, female-to-male transplantation, and mechanical circulatory support at transplantation were not significant in univariate analyses.CONCLUSIONS: Modest oversizing by DRWR (1.29 to 1.97) is associated with increased survival and lower risk in infant heart transplantation. Additional investigation is needed to establish best practices for size-matching in this population.

  View details for DOI 10.1016/j.athoracsur.2022.05.067

  View details for PubMedID 35835207

• Biomechanical Analysis of the Ross Procedure in an Ex Vivo Left Heart Simulator. World journal for pediatric & congenital heart surgery Bryan, A. Y., Brandon Strong, E., Kidambi, S., Gilligan-Steinberg, S., Bennett-Kennett, R., Lee, J. Y., Imbrie-Moore, A., Moye, S. C., Hendrickx-Rodriguez, S., Wang, H., Dauskardt, R. H., Joseph Woo, Y., Ma, M. R. 2022; 13 (2): 166-174

  Abstract

  BACKGROUND: Neo-aortic pulmonary autografts often experience root dilation and valve regurgitation over time. This study seeks to understand the biomechanical differences between aortic and neo-aortic pulmonary roots using a heart simulator.METHODS: Porcine aortic, neo-aortic pulmonary, and pulmonary roots (n=6) were mounted in a heart simulator (parameters: 100 mm Hg, 37 °C, 70 cycles per minute, 5.0 L/min cardiac output). Echocardiography was used to study root distensibility (percentage change in luminal diameter between systole and diastole) and valve function. Leaflet motion was tracked with high-speed videography. After 30 min in the simulator, leaflet thickness (via cryosectioning), and multiaxial modulus (via lenticular hydrostatic deformation testing) were obtained.RESULTS: There were no significant differences between aortic and neo-aortic pulmonary leaflet motion, including mean opening velocity (218 vs 248 mm/s, P=.27) or mean closing velocity (116 vs 157 mm/s, P=.12). Distensibility was similar between aortic (8.5%, 1.56 mm) and neo-aortic pulmonary (7.8%, 1.12 mm) roots (P=.59). Compared to virgin controls, native pulmonic roots exposed to systemic pressure for 30 min had reduced leaflet thickness (630 vs 385 m, P=.049) and a reduced Young's modulus (3,125 vs 1,089 kPa, P=.077). In contrast, the aortic roots exposed to pressure displayed no significant difference in aortic leaflet thickness (1,317 vs 1,256 m, P=.27) or modulus (5,931 vs 3,631 kPa, P=.56).CONCLUSIONS: Neo-aortic pulmonary roots demonstrated equivalence in valve function and distensibility but did experience changes in biomechanical properties and morphology. These changes may contribute to long-term complications associated with the Ross procedure.

  View details for DOI 10.1177/21501351211070288

  View details for PubMedID 35238706

• Multicenter experience with durable biventricular assist devices JOURNAL OF HEART AND LUNG TRANSPLANTATION Shah, P., Ha, R., Singh, R., Cotts, W., Adler, E., Kiernan, M., Brambatti, M., Meehan, K., Phillips, S., Kidambi, S., Macaluso, G. P., Banerjee, D., Mooney, D., Duc Pham, Pretorius, V. D. 2018; 37 (9): 1093–1101

  Abstract

  Severe right ventricular failure necessitating a right ventricular assist device (RVAD) complicates 6% to 11% of left ventricular assist device (LVAD) implants. Patient outcomes for those receiving durable continuous-flow VADs in a biventricular configuration (i.e., BiVAD) have been reported in limited case series.Data from United States centers with ≥ 6 BiVAD implants were collected. Characteristics and outcomes of patients receiving contemporaneous (i.e., same surgery) vs staged implantation of the HVAD as a BiVAD were compared.From 2011 to 2017, 46 patients received durable BiVADs and had the following characteristics: median age, 46 years (interquartile range [IQR], 19-67 years), non-ischemic cardiomyopathy (80%), bridge to transplant (83%), Interagency Registry for Mechanically Assisted Circulatory Support Profile 1 or 2 (92%), use of temporary circulatory support (37%), right atrial pressure 19 mm Hg (IQR, 14-23 mm Hg), and cardiac index of 1.6 liters/min/m2 (IQR, 1.2-2.1 liters/min/m2). Operative mortality was 33%. Equal numbers of patients received a right atrial or right ventricular implant. Contemporaneous BiVAD implantation occurred in 31 patients (67%), and compared with 15 patients (33%) with staged implants, these patients had a shorter intensive care unit length of stay of 12 days (IQR, 7-23 days) vs 42 days (IQR, 28-48 days, p = 0.035) and were more likely to be discharged from the hospital on BiVAD support (61% vs 27%, p = 0.04). RVAD thrombosis developed in 17 patients (37%). Patients with contemporaneous BiVAD implants had a 1-year survival of 74% compared with 40% in staged BiVAD patients (p = 0.11).Patients receiving durable BiVADs represent a critically ill patient population with severe biventricular failure who have high operative mortality and RVAD thrombosis rates. The 1-year survival for patients receiving contemporaneous BiVADs in experienced centers mirrors other contemporary durable biventricular support strategies.

  View details for PubMedID 30173824

• Minimally Invasive Thymectomy and Lung Volume Reduction in a Patient with Myasthenia Gravis. The Annals of thoracic surgery Salna, M., Kidambi, S., Sampson, J., Shrager, J. B. 2018

  Abstract

  We describe the case of a patient with myasthenia gravis and severe pulmonary emphysema who underwent concomitant bilateral video/robotic-assisted thymectomy with unilateral lung volume reduction surgery. We review the important pathophysiological considerations that must be appreciated to ensure safe surgery in this unusual situation with two diseases that independently affect the respiratory system - each of which requires preoperative optimization.

  View details for PubMedID 29807007

• Percutaneous, minimally invasive approach to implantable left ventricular assist device deactivation. The Journal of thoracic and cardiovascular surgery Kidambi, S. n., Shudo, Y. n., Dake, M. D., Woo, Y. J., Ha, R. V. 2017

  View details for PubMedID 29102456