François Roubertie

Biventricular stimulation improves right and left ventricular function after tetralogy of Fallot repair: acute animal and clinical studies.

BACKGROUND Optimal treatment of right ventricular (RV) dysfunction observed in patients after tetralogy of Fallot (TOF) repair is unclear. Studies of biventricular (BiV) stimulation in patients with congenital heart disease have been retrospective or have included patients with heterogeneous disorders. OBJECTIVE The purpose of this study was to determine the effects on cardiac function of stimulating at various cardiac sites in an animal model of RV dysfunction and dyssynchrony and in eight symptomatic adults with repaired TOF. METHODS Pulmonary stenosis and regurgitation as well as RV scars were induced in 15 piglets to mimic repaired TOF. The hemodynamic effects of various configurations of RV and BiV stimulation were compared with sinus rhythm (SR) 4 months after surgery. In eight adults with repaired TOF, RV and left ventricular (LV) dP/dt(max) were measured invasively during SR, apical RV stimulation, and BiV stimulation. RESULTS At 4 months, RV dilation, dysfunction, and dyssynchrony were present in all piglets. RV stimulation caused a decrease in LV function but no change in RV function. In contrast, BiV stimulation significantly improved LV and RV function (P < .05). Echocardiography and epicardial electrical mapping showed activation consistent with right bundle branch block during SR and marked resynchronization during BiV stimulation. In patients with repaired TOF, BiV stimulation increased significantly RV and LV dP/dt(max) (P < .05). CONCLUSION In this swine model of RV dysfunction and in adults with repaired TOF, BiV stimulation significantly improved RV and LV function by alleviating electromechanical dyssynchrony.

Biventricular pacing in patients with Tetralogy of Fallot: non-invasive epicardial mapping and clinical impact.

INTRODUCTION Patients who have undergone repair of Tetralogy of Fallot (TOF) often present with right bundle branch block. Cardiac resynchronization therapy (CRT) with right ventricular (RV) or biventricular (BiV) stimulation has been proposed as a modality to correct electrical abnormalities and improve cardiac contractility in patients with repaired TOF. We aimed to 1) compare ventricular electrical activation in adults with repaired TOF during RV versus BiV stimulation, using a non-invasive epicardial mapping system, and 2) examine the clinical mid-term effects of BiV resynchronization. METHODS 9 adults with repaired TOF were implanted with a CRT system and underwent 1) a non-invasive epicardial mapping (n=9) during sinus intrinsic rhythm, RV and BiV pacing 2) a clinical evaluation (n=7) before and after 6 months CRT with assessment of NYHA class and exercise capacity. RESULTS During intrinsic rhythm, non-invasive mapping demonstrated delayed activation of the right compared with the left ventricle in all patients, with the greatest activation delay noted near the infundibulum. However, we observed important differences among patients, in the severity of activation delays. Global activation time and an index of dyssynchrony were improved (p<0.05) during BiV pacing compared with RV pacing and spontaneous rhythm. BiV pacing increased (p<0.05) exercise tolerance and lowered the mean NYHA functional class at 6 months of follow up. CONCLUSION Patients with corrected TOF present with different patterns of ventricular activation. RV stimulation modestly improved RV activation sequence and was associated with a delayed LV activation. Biventricular stimulation significantly decreased right and left ventricular dyssynchrony.

Valve replacement in children: A challenge for a whole life

Valvular pathology in infants and children poses numerous challenges to the paediatric cardiac surgeon. Without question, valvular repair is the goal of intervention because restoration of valvular anatomy and physiology using native tissue allows for growth and a potentially better long-term outcome. When reconstruction fails or is not feasible, valve replacement becomes inevitable. Which valve for which position is controversial. Homograft and bioprosthetic valves achieve superior haemodynamic results initially but at the cost of accelerated degeneration. Small patient size and the risk of thromboembolism limit the usefulness of mechanical valves, and somatic outgrowth is an universal problem with all available prostheses. The goal of this article is to address valve replacement options for all four valve positions within the paediatric population. We review current literature and our practice to support our preferences. To summarize, a multitude of opinions and surgical experiences exist. Today, the valve choices that seem without controversy are bioprosthetic replacement of the tricuspid valve and Ross or Ross-Konno procedures when necessary for the aortic valve. On the other hand, bioprostheses may be implanted when annular pulmonary diameter is adequate; if not or in case of right ventricular outflow tract discontinuity, it is better to use a pulmonary homograft with the Ross procedure. Otherwise, a valved conduit. Mitral valve replacement remains the most problematic; the mechanical prosthesis must be placed in the annular position, avoiding oversizing. Future advances with tissue-engineered heart valves for all positions and new anticoagulants may change the landscape for valve replacement in the paediatric population.

Late Outcome of 132 Senning Procedures After 20 Years of Follow-Up

BACKGROUND Risk factors and rates of reoperation, arrhythmias, systemic right ventricular dysfunction (RVD), and late death after a Senning procedure were investigated. METHODS One-hundred thirty-two patients underwent a Senning operation between 1977 and 2004 (105 simple and 27 complex transpositions of the great arteries). Mean follow-up time was 19.5 ± 6.6 years. Surviving patients were evaluated by transthoracic echocardiography and electrocardiography. Right ventricular function was assessed in 70 patients by isotopic ventriculography or magnetic resonance imaging. RESULTS Operative and late mortality were 5.3% (7/132) and 9.6% (12/125), respectively. Nine patients were reoperated for left ventricular outflow tract obstruction or baffle stenosis. Survival rate was 91.5%, 91%, 89%, and 88% at 1, 5, 10, and 20 years, respectively. Probability of maintaining permanent sinus rhythm was 80%, 65%, 55%, and 44%. Twelve patients required pacemaker implantation. Probability of no supraventricular tachycardia, atrial flutter/fibrillation or ventricular tachycardia was 95.5%, 91.5%, 88%, and 75%, respectively. These parameters were similar for simple and complex transposition. Probability of right ventricular ejection fraction >40% was 100% at 5 and 10 years, and 98% at 20 years for simple transposition, and 100%, 92%, and 58% for complex transposition. This difference was statistically significant. Risk factors for RVD were complex transposition (p < 0.001), body weight (p = 0.008), no cardioplegia (p < 0.001), and tricuspid valve regurgitation (p = 0.004). CONCLUSIONS Senning procedure results in very good long-term survival out to 20 years. Both RVD and baffle stenosis were rare, but there was a concerning incidence of arrhythmia over time suggesting careful long-term surveillance.

The Performance of Hancock Porcine-Valved Dacron Conduit for Right Ventricular Outflow Tract Reconstruction

BACKGROUND The surgical reconstruction of right ventricle outflow tract (RVOT) often requires the implantation of a valved conduit. Homografts are lacking availability and are associated with limited durability in children. Our experience with the Hancock porcine-valved Dacron (DuPont, Wilmington, DE) conduit (Medtronic, Minneapolis, MN) was retrospectively assessed. METHODS Follow-up was studied in 214 survivors who underwent 247 conduit implants between January 1990 and January 2007. Pulmonary atresia/ventricular septal defect was present in 86 (40.2%) and truncus arteriosus in 62 (29%). Conduit implantation was associated with anatomic repair in 136, conduit replacement in 96, and secondary pulmonary valve insertion in 15. Median age at operation was 62.5 months (range, 1 week to 50 years), including 14 neonates (6%). Median conduit size was 17.4 mm because of routine over-sizing. Pulmonary bifurcation patch augmentation was necessary in 26 patients. Periodic echocardiography studies were performed for a median follow-up of 98 months (range, 13 to 142 months). RESULTS Three (1.4%) late deaths occurred. No conduit-related deaths or complications occurred. Conduit degeneration was associated with increase in valvular gradient. Valve regurgitation was absent or mild. Higher RVOT systolic pressure gradient at discharge did not influence conduit longevity. Conduit reoperation was delayed due to percutaneous balloon dilatation in 14 patients, associated with stenting in 7. Survival with freedom from conduit reoperation was 98% (95% confidence interval [CI], 97% to 100%) at 1 year, 81% (95% CI, 75% to 87%) at 5 years, and 32% (95% CI, 22% to 42%) at 10 years. CONCLUSIONS The Hancock valved conduit is a safe and reliable alternative to homografts. It appears to be appropriate in patients with limited pulmonary vascular bed and high pulmonary artery pressures. Caution is required in neonates because of the rigidity of the Dacron housing. Initial results with secondary percutaneous procedures are encouraging.

Multivariable assessment of the right ventricle by echocardiography in patients with repaired tetralogy of Fallot undergoing pulmonary valve replacement: A comparative study with magnetic resonance imaging

BACKGROUND Evaluation of the right ventricle (RV) using transthoracic echocardiography is challenging in patients with repaired tetralogy of Fallot (rTOF). AIMS To evaluate the accuracy of conventional echocardiographic variables and real-time three-dimensional echocardiography (RT3DE) in assessing right ventricular (RV) volumes and function compared with magnetic resonance imaging (MRI), in adult patients with rTOF and referred for pulmonary valve replacement (PVR). METHODS Complete echocardiography was performed on 26 consecutive patients referred for PVR, before and 1 year after surgery. All variables were compared with MRI. RESULTS Correlations between conventional variables and MRI were absent or poor when assessing RV ejection fraction (RVEF), except for fractional area of change (FAC; r=0.70, P<0.01 before PVR; r=0.68, P<0.01 after PVR) and RT3DE (r=0.96, P<0.01 before PVR; r=0.98, P<0.01 after PVR). The RV volume correlation between RT3DE and MRI was excellent before and after surgery for RV end-diastolic volume (r=0.88, P<0.01 and r=0.91, P<0.01, respectively) and RV end-systolic volume (r=0.92, P<0.01 and r=0.95, P<0.01, respectively). The accuracy of these indices, as a diagnostic test for impaired RV (<45%), was good: Youdens indexes varied from 0.47 to 0.89; areas under the receiver operating characteristic curve before and after PVR were 0.86 and 0.81 for FAC and 0.98 and 0.97 for RT3DE, respectively. CONCLUSION Commonly used echocardiography variables, such as tricuspid annular plane systolic excursion and tricuspid annular peak systolic velocity, did not sensitively evaluate global RVEF. A global approach, that includes the whole RV and integration of its different components, was more reliable in patients with rTOF.

Anomalous Origin of the Left Coronary Artery From the Pulmonary Artery Associated With Severe Left Ventricular Dysfunction: Results in Normothermia

BACKGROUND Repair of anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) carries a high risk of operation, particularly in those with poor left ventricular function. In this study, we assessed the outcomes of patients who presented with severe preoperative left ventricular dysfunction (shortening fraction <15%) who underwent the repair under normothermic bypass. METHODS Since September 2002, 21 infants with severe left ventricular dysfunction underwent surgical repair using a direct coronary reimplantation technique. Mean age of patients was 5.3 +/- 3.8 months. Moderate or severe mitral regurgitation present in 5 patients was not addressed at the operation. Repair was performed under normothermic cardiopulmonary bypass and myocardial protection was achieved by intermittent antegrade normothermic blood cardioplegia. RESULTS Mean cardiopulmonary bypass and cross-clamp times were 153.5 +/- 51 and 50 +/- 14.5 minutes, respectively. There was one (4.7%) early death because of sudden cardiac arrest 48 hours after successful weaning from mechanical ventilation. One patient required urgent left coronary artery stenting on the 34th postoperative day because of early reimplantation failure. There was no late death. Echocardiographic evaluation revealed a significant improvement in terms of shortening fraction (preoperative, 10.3 +/- 3.2% vs follow-up, 33 +/- 7.7%, p < 0.0001). CONCLUSIONS Our results suggest that the repair of anomalous origin of the left coronary artery from the pulmonary artery can be accomplished with acceptable mortality and morbidity rates even in patients having severely depressed left ventricular function. Normothermic cardiopulmonary bypass is safe and effective in children who have a limited tolerance to further ischemic insult.

Intra-diaphragmatic pacemaker implantation in very low weight premature neonate.

Implantation of a pacemaker (PM) in very low weight premature neonates can be a challenging procedure because of the actual dimension of generators. Ideal placement of the PM is still controversial. We describe a technique of intra-diaphragmatic PM implantation in a 1.3 kg neonate.

Validation of an animal model of right ventricular dysfunction and right bundle branch block to create close physiology to postoperative tetralogy of Fallot

BACKGROUND In the past 5 years a few number of studies and case reports have come out focusing on biventricular (BiV) stimulation for treatment of congenital heart disease related ventricular dysfunction. The few available studies include a diverse group of pathophysiological entities ranging from a previously repaired tetralogy of Fallot (TOF) to a functional single ventricle anatomy. Patients status is too heterogeneous to build important prospective study. To well understand the implication of prolonged electromechanical dyssynchrony we performed a chronic animal model that mimics essential parameters of postoperative TOF. METHODS Significant pulmonary regurgitation, mild stenosis, as well as right ventricular outflow tract (RVOT) scars were induced in 15 piglets to mimic repaired TOF. 4 months after hemodynamics and dyssynchrony parameters were compared with a control group and with a population of symptomatic adult with repaired TOF. RESULTS Comparing the animal model with the animal control group on echocardiography, RV dilatation, RV and LV dysfunction, broad QRS complex and dyssynchrony were observed on the animal model piglets. Moreover, epicardial electrical mapping showed activation consistent with a right bundle branch block. The animal models displayed the same pathophysiological parameters as the post TOF repair patients in terms of QRS duration, pulmonary regurgitation biventricular dysfunction and dyssynchrony. CONCLUSION This chronic swine model mimics electromechanical ventricular activation delay, RV and LV dysfunction, as in adult population of repair TOF. It does appear to be a very useful and interesting model to study the implication of dyssynchrony and the interest of resynchronization therapy in TOF failing ventricle.

Early to Midterm Results of Total Cavopulmonary Connection in Adult Patients

BACKGROUND Total cavopulmonary connection (TCPC) has not been studied in adults. We investigated early and midterm morbidity and mortality in adults undergoing TCPC and assessed risk factors for mortality. METHODS Between June 1994 and October 2010, 30 adults (21.3 ± 5.5 years) underwent TCPC (extracardiac conduit). Twenty-two patients who had palliated single ventricles underwent TCPC completions and 8 patients underwent TCPC conversions. Preoperative and perioperative data were reviewed retrospectively. RESULTS Six of 9 patients with preoperative atrial flutter or fibrillation or intraatrial reentry tachycardia were treated in the catheterization room. An aortic cross-clamp was necessary in 12 patients, and 16 TCPCs were fenestrated. Mean follow-up was 51 months (range, 4-198 months). Early mortality was 10%: 2 of 8 conversions and 1 of 22 completions. There was 1 late conversion death (at 56 months postoperatively). Postoperatively, 4 patients required pacemakers and 1 patient required long-term antiarrhythmic medication, but no heart transplantations were necessary. Risk factors for early mortality were arrhythmia (p = 0.02), aortic cross-clamp (p = 0.054), and extracorporeal circulation in hypothermia (p = 0.03). Risk factors for overall mortality were conversion (p = 0.047), absence of fenestration (p = 0.036), surgery before January 2006 (p = 0.036), aortic cross-clamp (p = 0.018), extracorporeal circulation in hypothermia (p = 0.008), and arrhythmia (p = 0.005). New York Heart Association functional class had improved at the last follow-up: preoperatively, 17 patients were in class II and 12 patients were in class III versus 18 patients in class I and 9 patients in class II postoperatively (p < 0.001). At the last clinical visit, systemic ventricular function was maintained, and no late supraventricular arrhythmia was found. CONCLUSIONS Early and midterm TCPC results for adults are encouraging for completion but are disappointing for conversion. Identified risk factors for mortality should improve patient selection for TCPC.