Faculty Bibliography

Congenitally corrected transposition of the great arteries (CCTGA) is a rare congenital heart lesion with varied morphological presentation and can often by asymptomatic. A failing systemic right ventricle (RV) or increasing tricuspid regurgitation are generally indications for surgical intervention. The surgical approach depends upon the age of the patient and morphology of the lesion. Anatomical correction is associated with satisfactory long-term results.

Open heart surgery on infants with congenital heart lesions can be challenging not only in terms of the surgical procedure itself but also for setting up ideal conditions for safe and smooth conduct of cardiopulmonary bypass (CPB). The surgeon has to deal with a variety of lesions in a subgroup of patients who offer little room for any error. Familiarity with the principles of CPB, check lists and protocols go a long way in improving outcome in this critical group of patients.

Objective: The objective of this experimental study was to test the underlying physical laws behind a proposed novel device for failing Fontan and to investigate whether the device could be implemented theoretically to improve hemodynamics in failing Fontan circulation.
Method(s): A 4-arm setup (Figure 1) was designed and fabricated to simulate an actual Fontan circuit in the form of a junction of the superior and inferior vena cava (SVC, IVC) and the right and left pulmonary arteries (RPA, LPA). A provision for placement of an oscillating ball along the RPA-LPA path to provide a push to the fluid away from SVC and IVC was created. The setup was designed to vary the rate of oscillation of the ball, and the initial pressure of the fluid on SVC and IVC limbs. The time for pressure drop at the SVC and IVC was measured at varying oscillations of the ball and varying resistances in the RPA-LPA pathway. The test was considered positive if increasing oscillations of the ball allowed for quicker pressure drop in the SVC and IVC (indicating quicker discharge of fluid through the LPA and RPA). A total of 48 different experiments were conducted to simulate different physical conditions including without the ball and a graph of the results was plotted and analyzed to conclude (Graph 1).
Result(s): The time required for pressure drop in the experiment without the ball was the least across all set of readings. This meant that placing an oscillating ball along the RPA-LPA path obstructed fluid flow rather than enhancing it. It was also observed that increasing the rate of oscillation of the ball increased the degree of obstruction to flow.
Conclusion(s): The proposed novel method for intervention is not a suitable option for improving hemodynamics in failing Fontan circulation. (Figure Presented)

OBJECTIVE:Femoral vein homograft can be used be used as valved right ventricle to pulmonary artery conduit in the Norwood operation. We describe the results of this approach, including pulmonary artery growth and ventricular function. METHODS:A retrospective chart review of 24 consecutive neonates with hypoplastic left heart syndrome or complex single ventricle undergoing this approach between June 2012 and December 2017 was performed. Conduit valve competency and ventricular function were estimated using transthoracic echocardiogram, and pulmonary artery growth was measured using Nakata's index. Changes in ventricular function pre-Glenn and at latest follow-up were assessed by ordinal logistic regression with a general linear model to account for the correlation within the same patient over time. RESULTS:). Right ventricular function was preserved in 83% of patients at a median follow-up of 34 (interquartile range, 10-46) months. CONCLUSIONS:Femoral vein homograft as a right ventricle to pulmonary artery conduit in the Norwood operation is safe and associated with good pulmonary artery growth and preserved ventricular function as assessed by subjective echocardiography. Catheter intervention of the conduit may be necessary.

BACKGROUND:A surgical pulmonary artery band (PAB) is used to control excessive pulmonary blood flow for certain congenital heart diseases. Previous attempts have been made to develop a transcatheter, implantable pulmonary flow restrictor (PFR) without great success. We modified a microvascular plug (MVP) to be used as a PFR. The objectives of this study were to demonstrate feasibility of transcatheter implantation and retrieval of the modified MVP as a PFR, and compare PA growth while using the PFR versus PAB. METHODS AND RESULTS/RESULTS:The PFR was implanted in eight newborn piglets in bilateral branch pulmonary arteries (PAs). Immediately post-PFR implantation, the right ventricular systolic pressure increased from a median of 20-51 mmHg. Transcatheter retrieval of PFR was 100% successful at 3, 6, and 9 weeks and 50% at 12-weeks post-implant. A left PAB was placed via thoracotomy in four other newborn piglets. Debanding was performed 6-weeks later via balloon angioplasty. On follow-up, the proximal left PA diameters in the PFR and the PAB groups were similar (median 8 vs. 7.1 mm; p = 0.11); albeit the surgical band sites required repeat balloon angioplasty secondary to recurrent stenosis. By histopathology, there was grade II vessel injury in two pigs immediately post-retrieval of PFR that healed by 12 weeks. CONCLUSIONS:Transcatheter implantation and retrieval of the MVP as a PFR is feasible. PA growth is comparable to surgical PAB, which is likely to require reinterventions. The use of the MVP as a PFR in humans has to be trialed before recommending its routine use.

Mechanical circulatory support for infants with single ventricle physiology remains challenging. Utilization of a ventricular assist device (VAD) has potential advantages over extracorporeal circulatory membrane oxygenation. As such, VAD utilization in single ventricle patients with refractory heart failure continues to be explored. Herein, we describe a novel VAD strategy to support an infant with Glenn physiology who presented in cardiogenic shock related to myocardial depression of unknown etiology. This VAD configuration supported the systemic circulation independent of the Glenn circulation. Seven days of VAD support resulted in recovery of myocardial and end-organ function leading to VAD removal. The patient remains alive and free from transplantation 16 months post VAD explantation.

Infants with dextrocardia-heterotaxy syndrome pose significant surgical challenges to a successful orthotopic heart transplant. Herein we report on 2 infants with dextrocardia-heterotaxy syndrome who underwent complex heart transplantation. A combination of preoperative 3-dimensional chest computed tomography to predict optimal donor size and unique surgical technique resulted in successful outcomes.