Babar Hasan

Short-Term Performance of the Transcatheter Melody Valve in High-Pressure Hemodynamic Environments in the Pulmonary and Systemic Circulations

Background— The Melody valve is approved for percutaneous pulmonary valve replacement in dysfunctional right ventricular outflow tracts. The function of this valve when subjected to high-pressure loads in humans is unknown. The aim of this study was to describe the immediate and short-term results of Melody valves implanted in a high-pressure environment. Methods and Results— Definitions of a high-pressure system were established for Melody valves implanted in the systemic (ie, aortic or mitral position) and pulmonary (ie, right ventricular outflow tract conduit or tricuspid valve annulus) circulations. Implants in these environments were ascertained from databases of the 5 centers that participated in the US Investigational Device Exemption trial. Thirty implants met the inclusion criteria: 23 pulmonary circulation implants (all in the pulmonary position) systemic circulation implants (5 in the native aortic position, 1 in a left ventricle-to-descending aorta conduit, and 1 in the mitral annulus). All pulmonary circulation implants were performed percutaneously in the catheterization laboratory. A hybrid approach (surgical exposure for transcatheter implant) was used for 4 of the aortic implants. There were no procedure-related deaths. Three patients died of nonprocedure- and nonvalve-related causes. At 1 year, freedom from moderate to severe regurgitation was 100%, and freedom from mild regurgitation was 90%. Freedom from moderate to severe stenosis was 86% at 1 year. Conclusions— Short-term performance of the Melody valve in high-pressure environments is encouraging, with good valve function in all patients.

Effects of Transcatheter Pulmonary Valve Replacement on the Hemodynamic and Ventricular Response to Exercise in Patients With Obstructed Right Ventricle-to-Pulmonary Artery Conduits

OBJECTIVES This study sought to investigate the effects of exercise on the right ventricle in patients with an obstructed right ventricular outflow tract (RVOT) conduit before and after transcatheter pulmonary valve replacement (TPVR). BACKGROUND Conventionally, assessment of the right ventricle in congenital heart disease patients with dysfunctional RVOT conduits is performed at rest. However, this does not reflect dynamic exercise changes. METHODS Exercise stress echocardiography (ESE) before and 6 months after TPVR was performed. ESE protocol included measurement of rest and immediate post-exercise RVOT maximal instantaneous gradients (MIGs), right ventricular (RV) systolic pressure, 2-dimensional fractional area change, and global longitudinal strain (GLS). RESULTS Twenty patients with RVOT conduit obstruction (median age, 18 years), the majority (n = 14) with tetralogy of Fallot, completed the study. Pre-TPVR, the median resting MIG across the RVOT was 53 mm Hg (23 to 95 mm Hg) and increased to 93 mm Hg (49 to 156 mm Hg; p < 0.001) with exercise. After TPVR, the median MIG at rest was 26 mm Hg (6 to 41 mm Hg, and after exercise, it was 45 mm Hg (9 to 102 mm Hg), both significantly lower than before TPVR (p ≤ 0.001), but there was still a substantial increase in gradient with exercise in many patients. The RV fractional area change, RV GLS, and left ventricular GLS, both at rest and after exercise, were significantly greater after TPVR than before. A greater pre-TPVR exercise-related increase in RV function was associated with improvement in peak Vo2 after TPVR (p = 0.01). CONCLUSIONS In patients with obstructed RVOT conduits, TPVR resulted in significant improvement in conduit stenosis and RV function at both rest and at peak exercise and in exercise cardiopulmonary function. The ability to augment RV function at peak exercise before TPVR was associated with improved exercise capacity 6 months after TPVR.

Outcomes of transcatheter approach for initial treatment of pulmonary atresia with intact ventricular septum

To review the short and medium term outcome of transcatheter pulmonary valve perforation (PVP) in patients with pulmonary atresia‐intact ventricular septum and non‐right ventricular dependant coronary circulation (PA/IVS non‐RVDCC).

Impact of Transcatheter Pulmonary Valve Replacement on Biventricular Strain and Synchrony Assessed by Cardiac Magnetic Resonance Feature Tracking

Background—Transcatheter pulmonary valve (TPV) replacement is an emerging therapy intended to restore pulmonary valve function in patients with right ventricular outflow tract conduit dysfunction; the impact of this technique on ventricular strain and synchrony is not known. Methods and Results—Cardiac magnetic resonance and ECG data acquired at 1 center as part of the US Melody TPV trial were analyzed. Biventricular strain and mechanical synchrony measurements were made based on short-axis and 4-chamber steady-state free precession images using feature tracking software. Post- versus pre-TPV replacement findings were compared for all patients (n=31) and subgroups with predominant pulmonary regurgitation (n=13) or stenosis (n=18). Most patients had tetralogy of Fallot (18/31). After TPV replacement, left ventricular (LV) circumferential strain increased for the whole cohort (P<0.001) and both subgroups (pulmonary regurgitation P=0.01; pulmonary stenosis P=0.02). LV longitudinal strain increased for the whole cohort (P=0.02) and pulmonary regurgitation subgroup (P=0.05); circumferential right ventricular strain increased for the pulmonary stenosis group only (P=0.05). LV longitudinal synchrony improved significantly in the pulmonary regurgitation group (maximum wall delay P=0.03; cross-correlation delay P=0.01). Electric measures of synchrony did not improve. Conclusions—In patients with right ventricular outflow tract conduit dysfunction, TPV replacement is associated with improved global LV strain, as well as improved right ventricular strain and LV synchrony in subgroups. Given the associations between strain and synchrony and clinical outcomes, these findings support potential long-term benefits of TPV replacement.

Late Pulmonary Valve Replacement in Patients With Pulmonary Atresia and Intact Ventricular Septum: A Case-Matched Study

BACKGROUND Pulmonary valve replacement (PVR) is a common therapy for chronic pulmonary regurgitation. However, the use of this strategy is mostly based on the studies performed on patients with tetralogy of Fallot (TOF) and not in patients with pulmonary atresia/intact ventricular septum (PA/IVS). The aim of this study is to evaluate our experience with PVR in patients with PA/IVS and compare them with a matched cohort of TOF patients. METHODS Between 1995 and 2009, 13 patients with PA/IVS underwent a late PVR. Matched TOF control subjects were identified for 12 of these patients. Before and after PVR echocardiographic, magnetic resonance imaging, exercise test, Holter, and electrocardiographic data were compared between groups. RESULTS There was no mortality in either group. The PVR improved pulmonary regurgitant fraction and right ventricular volumes in all patients. Patients with PA/IVS had more significant tricuspid regurgitation (TR [at least moderate]) by echocardiography and magnetic resonance imaging before PVR (n = 11 [85%] versus n = 1 [8%]; p = 0.003) and had more tricuspid valve repairs than TOF patients (n = 9 [69%] versus n = 1 [8%]; p = 0.004). Repair was undertaken by a combination of techniques. Although TR was improved early postoperatively, only 2 of 9 patients (22%) were free from significant TR at most recent follow-up (median 2.5 years; range, 0.1 to 10.9). No patient underwent reoperation at latest follow-up. CONCLUSIONS Patients with PA/IVS can undergo a late PVR with excellent results. Significant TR and repair are more commonly observed among patients with PA/IVS compared with TOF patients. Although tricuspid valve repair improves regurgitation early, TR tends to recur, suggesting the need for further refinement of current surgical techniques.

Exercise Stress Echocardiographic Assessment of Outflow Tract and Ventricular Function in Patients With an Obstructed Right Ventricular-to-Pulmonary Artery Conduit After Repair of Conotruncal Heart Defects

This study assessed right ventricular (RV) and RV outflow tract (RVOT) function and pressure in response to exercise in patients with an obstructed RV-pulmonary artery (PA) conduit using exercise stress echocardiography (ESE) to evaluate these parameters. RV-PA conduits inevitably develop stenosis and/or regurgitation over time. Assessment of conduit obstruction only at rest may not reveal the extent of physiologic perturbation related to RV pressure loading. Patients with a stenotic RV-PA conduit who were being considered for transcatheter pulmonary valve placement were approached prospectively. ESE was performed and ventricular images were obtained at rest and at peak exercise. Forty patients (median age 17 years) were enrolled. Most patients had tetralogy of Fallot (63%) and were in New York Heart Association class II (59%). Exercise stress echocardiographic images were adequate in 38 patients (95%). With exercise there was a significant increase in maximum instantaneous RVOT gradient from rest (59 vs 96 mm Hg, p <0.001); exercise-induced change in RVOT gradient correlated with global RV strain at rest (r = -0.3, p = 0.05). Compared to measurements at rest there were significant increases in median peak longitudinal strain of the left ventricular free wall, interventricular septum, and global left ventricular strain at peak exercise. There were no significant changes in median RV strain at peak exercise (RV free wall -14.3 [-26, -8] at rest vs -15.2 [-27, -3] at peak exercise, p = 0.87; global RV strain -13.9 [-32, -9] vs -15.1 [-23, -6], p = 0.11). In conclusion, using ESE it was possible to evaluate abnormal ventricular function and conduit dysfunction at peak exercise in patients with an obstructed RV-PA conduit.

Impact of International Quality Improvement Collaborative on Congenital Heart Surgery in Pakistan

Background The International Quality Improvement Collaborative (IQIC) was formed to reduce mortality and morbidity from congenital heart disease (CHD) surgeries in low/middle-income countries. Objectives We conducted this study to compare the postoperative outcomes of CHD surgeries at a centre in Pakistan before and after joining IQIC. Methods The IQIC provides guidelines targeting key drivers responsible for morbidity and mortality in postoperativepatients with CHD. We focused primarily on nurse empowerment and improving the infection control strategies at our centre. Patients with CHD who underwent surgery at this site during the period 2011–2012 (pre-IQIC) were comparedwith those getting surgery in 2013–2014 (post-IQIC). Morbidity (major infections), mortality and factors associated with them were assessed. Results There was a significant decrease in surgical site infections and bacterial sepsis in the post-IQIC versus pre-IQIC period (1% vs 30%, p=0.0001, respectively). A statistically insignificant decrease in the mortality rate was also noted in post-IQIC versus pre-IQIC period (6% vs 9%, p=0.17, respectively). Durations of ventilation and intensive care unit (ICU) and hospital stay were significantly reduced in the post-IQIC period. Age <1 year, malnutrition, low preoperative oxygen perfusion, Risk Adjustment for Congenital Heart Surgery score >3, major chromosomal anomalies, perfusion-related event, longer ventilation and ICU/hospital stay durations were associated with greater odds of morbidity and mortality. Conclusion Enrolling in the IQIC programme was associated with an improvement in the postsurgical outcomes of the CHD surgeries at our centre.

Effect of L-type calcium channel blocker (amlodipine) on myocardial iron deposition in patients with thalassaemia with moderate-to-severe myocardial iron deposition: protocol for a randomised, controlled trial

Introduction Sideroblastic cardiomyopathy secondary to repeated blood transfusions is a feared complication in thalassaemia. Control of myocardial iron is thus becoming the cornerstone of thalassaemia management. Recent evidence suggests a role for L-type Ca2+ channels in mediating iron uptake by the heart. Blocking the cellular iron uptake through these channels may add to the benefit of therapy to standard chelation in reducing myocardial iron. We aim to determine the efficacy of amlodipine (a calcium channel blocker) as an adjunct to standard aggressive chelation in retarding myocardial iron deposition in thalassaemics with or without cardiomyopathy. Outcomes The primary outcome is to compare the efficacy of amlodipine+chelation (intervention) versus standard chelation (control) in retarding myocardial iron deposition. Secondary outcomes include the effect of amlodipine therapy on systolic and diastolic function, strain and strain rate and liver iron content. Methods and analysis This is a single-centre, parallel-group, prospective randomised control trial. Twenty patients will be randomised in a 1:1 allocation ratio into the intervention and control arms. In addition to conventional echocardiography, MRI T2* values for assessment of cardiac and liver iron load will be obtained at baseline and at 6 and 12 months. Cardiac T2* will be reported as the geometric mean and per cent coefficient of variation, and an increase in cardiac T2* values from baseline will be used as an end point to compare the efficacy of therapy. A p Value of <0.05 will be considered significant. Study setting Department of Pediatric and Child Health, Aga Khan University Hospital, Karachi, Pakistan. Ethics and dissemination This study has been approved by the Ethics Review Committee and Clinical Trials Unit at The Aga Khan University with respect to scientific content and compliance with applicable research and human subjects regulations. Findings will be reported through scientific publications and research conferences and project summary papers for participants. Trial registration number ClinicalTrials.Gov. Registration no: NCT02065492.

Electrical dyssynchrony and endocardial fibroelastosis resection in the rehabilitation of hypoplastic left cardiac syndrome.

BACKGROUND Staged left ventricular rehabilitation is a novel surgical approach in patients undergoing single ventricle palliation for borderline hypoplastic left cardiac disease, in an attempt to salvage the left ventricle. The procedure includes resection of endocardial fibroelastosis from the left ventricular free wall and apex. We hypothesised that endocardial fibroelastosis removal may significantly affect ventricular conduction and myocardial electrical characteristics. METHODS This study included 27 patients with borderline hypoplastic left cardiac syndrome who underwent staged left ventricle rehabilitation with endocardial fibroelastosis resection following single ventricle palliation. The effect on electrical synchrony was measured by ventricular depolarisation timing (QRS duration) on electrocardiogram. Patients were evaluated for a change in QRS duration before and after fibroelastosis removal and at most recent follow-up. RESULTS The QRS change in the immediate period after endocardial fibroelastosis resection ranged from -16 to 36 milliseconds with a median of 0 (p = 0.09). However, long-term conduction delay was common in 44% (12/27) of patients having a QRS duration greater than 98th percentile for the age at the most recent electrocardiogram. Only one patient had QRS duration greater than 98th percentile before any surgical procedure. Two patients developed left bundle branch block and one developed right bundle branch block with left, but anterior-fascicular block. Overall, the QRS duration correlated with left ventricular size (R = 0.54, p = 0.006) at the most recent electrocardiogram. CONCLUSIONS Electrical dyssynchrony is a common finding in patients undergoing staged left ventricular rehabilitation after single ventricle palliation; however, it is not acutely related to surgical endocardial resection. Left ventricular size is correlated with QRS duration. Diligent follow-up is required to evaluate the effects of left ventricular growth and consideration of resynchronisation in this population.

Postnatal Angiographic Appearance of Left Ventricular Myocardium in Fetal Patients With Aortic Stenosis Having In-Utero Aortic Valvuloplasty

Fetal aortic valvuloplasty (FAV) is performed on the basis of the hypothesis that aortic stenosis leads to the impairment of left ventricular (LV) filling and growth. Given that most fetuses fail to exhibit normalization of LV growth even after successful FAV, better understanding of the associated LV myocardial pathology is indicated. Postnatal angiography was reviewed retrospectively for all patients who (1) underwent FAV for severe aortic stenosis and (2) had well-opacified LV angiograms before any surgical intervention from 2000 to 2007. The angiographic appearance of the LV myocardium was described as either smooth or trabeculated in a total of 6 anatomic segments in 2 projections (anteroposterior and lateral). Twenty-four infants who underwent FAV had angiographic images appropriate for review. Of these, 4 (17%) had uniformly smooth LV myocardium, whereas 20 (83%) had deep trabeculations of > or =1 LV myocardial segment. Half of the infants (n = 13) had extensive trabeculations with the involvement of > or =4 segments. In all cases, the septal segments were smooth. In conclusion, patients after FAV have angiographically abnormal left ventricles, commonly involving extensive trabeculations of the free wall, but without septal involvement.