Mark A. Walsh

Percutaneous pulmonary valve implantation within bioprosthetic valves

AIMS Replacement of bioprosthetic valves in the right ventricular (RV) outflow tract (RVOT) is inevitable due to acquired valvar dysfunction. Percutaneous pulmonary valve implantation (PPVI) may result in acceptable clinical improvement avoiding surgical reintervention. To report outcomes of PPVI in dysfunctional surgically implanted bioprosthetic valves. METHODS AND RESULTS All children undergoing PPVI into a bioprosthetic pulmonary valve between October 2005 and February 2008 were reviewed. Acute haemodynamic changes were compared and an analysis of variance applied to assess changes in ventricular geometry and pressure over time. Fourteen children (seven males), median weight 57.8 kg and 14.7 years of age were identified, with an echocardiographic RVOT gradient of 59.6 +/- 26.8 mmHg and a pulmonary regurgitation (PR) grade of 3.6 +/- 0.8 (out of 4). Implantation was successful in all. Twenty-four hours after implantation, there was a significant improvement in RV pressure (RVP) (from 82.2 +/- 15.6 to 59.4 +/- 9.9 mmHg, P < 0.001) and degree of PR to 0.6 +/- 0.9 (P < 0.001). Mean hospital stay was 2.0 +/- 0.4 days. Freedom from reintervention was 92 and 89% at 1 and 2 years, respectively. Follow-up echocardiography (mean 12.9 +/- 9.8 months) revealed a further reduction in RVP (P < 0.001) and RVOT gradients (P < 0.001) and an increase in left ventricular end-diastolic volume (P= 0.01) and aortic valve annulus diameters (P < 0.001). CONCLUSIONS Percutaneous pulmonary valve implantation for RVOT dysfunction in a previously implanted prosthetic valve is feasible and safe. Short-term follow-up data are encouraging, yet longer-term information is required to determine if this form of palliation has a significant impact on management strategies.

Left ventricular morphology influences mortality after the Norwood operation

Background: Within the spectrum of congenital heart disease referred to as hypoplastic left heart syndrome (HLHS), there is variation in the morphology and function of the left ventricle which could influence outcomes after stage I Norwood palliation. Objective: To determine if left ventricular (LV) morphology is associated with outcome after stage I Norwood palliation for HLHS. Methods: Echocardiograms were reviewed from 108 patients who had undergone Norwood palliation at our institution over the past 11 years. Total cardiac diameter, thickness of the interventricular septum (IVS), LV area and LV myocardial area were calculated. Competing risk analysis was performed for survival to a stage II operation and to determine potential predictors. Results: From the Norwood operation up to stage II operation, mortality was predicted by IVS thickness, while the absence of right ventricular (RV) dysfunction was predictive of survival to stage II operation. For the complete pathway, from Norwood to the Fontan operation, mortality was predicted by IVS, a lower RV fractional area change and the presence of significant tricuspid regurgitation. Cardiac transplantation during this period was predicted by a lower RV fractional area change (p = 0.02) and a larger LV area in diastole. Conclusions: These results indicate that LV hypertrophy and decreased RV function adversely effect survival after the Norwood operation. They suggest that LV morphology, especially septal hypertrophy, can influence outcomes in HLHS and should be considered when evaluating treatment options.

Airway pressure release ventilation improves pulmonary blood flow in infants after cardiac surgery

Objective:We hypothesized that spontaneous inspiratory effort transmitted to the pleural space during airway pressure release ventilation would result in increased lung perfusion after surgery for tetralogy of Fallot or following a cavopulmonary shunt as a consequence of transient decreases in intrapleural pressure. Design:Prospective crossover cohort study. Setting:A tertiary care cardiac pediatric intensive care unit. Patients:Children after tetralogy of Fallot repair, cavopulmonary shunt, or Fontan operation. Interventions:Lung perfusion and cardiac output were measured during airway pressure release ventilation and pressure control ventilation with pressure support, both with and without spontaneous ventilation. Oxygen consumption was measured (mass spectrometer) and lung perfusion/cardiac output calculated (Fick equation). Constant levels of CO2 and mean airway pressure were targeted in all study phases. Measurements and Main Results:Twenty patients were enrolled in the study, nine after repair of tetralogy of Fallot and 11 after a cavopulmonary shunt. In the absence of spontaneous ventilation, there were no differences in lung perfusion or any of the measured gas exchange or hemodynamic parameters. In the presence of spontaneous ventilation for all patients, mean pulmonary blood flow increased from 2.4 to 2.9 L·min−1M−2 (p = .02). Oxygen delivery increased from 594 to 774 mL/min/m2 (p = .05) in the patients with tetralogy of Fallot patients and from 473 to 518 L·min−1M−2 (p = .07) in the cavopulmonary shunt group. Conclusion:Ventilation with airway pressure release ventilation (at comparable mean airway pressure) improves lung perfusion compared with pressure control ventilation in children after tetralogy of Fallot repair and cavopulmonary shunt operations. Although this study focused on tetralogy of Fallot and cavopulmonary shunt operations, the improved cardiopulmonary interactions may be beneficial in other situations in which hemodynamics are impaired by positive pressure ventilation.

Radiofrequency perforation of the right ventricular outflow tract as a palliative strategy for pulmonary atresia with ventricular septal defect.

Radiofrequency perforation (RF) of the right ventricular outflow tract (RVOT), while an effective management strategy in children with an intact ventricular septum, has not been fully detailed in those presenting with a ventricular septal defect.

Conduction Abnormalities in Pediatric Patients With Restrictive Cardiomyopathy

Background—Pediatric restrictive cardiomyopathy carries a poor prognosis secondary to a high risk of sudden death previously attributed to ventricular tachyarrhythmias. The extent of conduction abnormalities in this population and their relationship to life-threatening events has not been previously reported. Methods and Results—A retrospective study of pediatric patients with restrictive cardiomyopathy diagnosed between April 1994 and May 2011 was performed. Demographic, cardiac, and ECG characteristics and the mechanisms of serious arrhythmic events (death or episode of acute hemodynamic compromise thought to be secondary to arrhythmia) were evaluated. Sixteen patients (1–17 years of age) were reviewed, with 5 sudden cardiac events noted, including 4 deaths. Two deaths were caused by development of acute heart block; another patient with syncope had intermittent heart block and survived as the result of pacing features of an implanted defibrillator system. The median PR interval (222 versus 144 ms; P<0.01) and the QRS duration (111 versus 74; P=0.01) were significantly longer in those who had an acute cardiac event. Older age at presentation was associated with sudden cardiac events (P<0.01). No other functional or echocardiographic variables were associated with a sudden cardiac event. Conclusions—Pediatric patients with restrictive cardiomyopathy are at risk for acute high-grade heart block, and, in this cohort, bradycardic events represented a significant portion of all arrhythmic events. Aggressive ECG monitoring strategies looking for conduction system disease should be ongoing in all patients with restrictive cardiomyopathy. Implantation of a defibrillator/pacemaker should be considered as prophylactic management.

Surgical Repair of the Mitral Valve in Children With Dilated Cardiomyopathy and Mitral Regurgitation

BACKGROUND Significant mitral regurgitation is known to exacerbate left ventricular dysfunction in dilated cardiomyopathy. Although intervention on the regurgitant mitral valve is frequently described in adults, there is little pediatric data. METHODS Five children (aged 3 months to 4 years) with dilated cardiomyopathy and mitral regurgitation underwent mitral valve repair between January 1999 and January 2007 at our institution. All had mitral regurgitation graded as moderate to severe, with ejection fractions of 35% to 60% (median 53%). RESULTS There were no deaths; all children were weaned from cardiopulmonary bypass; 1 child required cardiac transplantation 3 weeks after repair. After surgery, mitral regurgitation was moderate in 1 patient, mild in 2 patients, and trivial in 2 patients. The 4 successful cases showed an improvement in functional status at latest follow-up (range, 8 years to 4 months): all were asymptomatic (4 children had preoperative symptoms). Successful cases showed a decreased left atrial dimension (mean z-score 3.8 to 2.6) and a decreased left ventricular end-diastolic diameter (mean 6.9 +/- 1.6 to 5.4 +/- 1.2). Ejection fraction and left ventricular end-systolic index did not show an improvement and declined in some cases. CONCLUSIONS We conclude that repair of the mitral valve is feasible in children with dilated cardiomyopathy and acquired mitral regurgitation. Most of the children demonstrated decreased left ventricular chamber sizes and an improved functional status. Although this operation improves symptoms, it is not clear whether it postpones or abrogates the need for cardiac transplantation.

Percutaneous closure of postoperative ventricular septal defects with the Amplatzer device.

The objective of this study was to look at the procedure, the results, and the follow‐up of patients who underwent percutaneous closure of a residual ventricular septal defect (VSD) following a surgical closure using the Amplatzer VSD device. Four patients had an original diagnosis of tetralogy of Fallot, two patients had a patch leak following a surgical repair of a VSD, and three patients had a VSD not repaired at the time of surgery. All patients fulfilled the currently accepted surgical criterion for reoperation (Qp/Qs > 1.5). The mean Qp/Qs was 1.8 ± 0.3 (1.5–2.3). Four patients underwent VSD closure using an Amplatzer perimembranous VSD device and in five patients an Amplatzer muscular VSD device was implanted. We performed percutaneous closure in nine patients. The size of the residual shunt ranged from 6 to 14 mm and the size of device used ranged from 8 to 16 mm. The arteriovenous loop needed to be recreated in two patients because of failure to advance the delivery sheath. There was complete closure of the defect in six cases, and a small residual shunt remained in three cases. Percutaneous closure of postoperative VSDs appears to be an effective way to resolve a hemodynamically significant residual shunt. There were no difficulties encountered with implantation of the devices. These promising short‐term results need reinforcement with additional long‐term data.

Significant correlation of comprehensive Aristotle score with total cardiac output during the early postoperative period after the Norwood procedure

BACKGROUND The comprehensive Aristotle score has been proposed as an individualized measure of the complexity of a given surgical procedure and has been reported to significantly correlate with postoperative morbidity and mortality after the Norwood procedure. An important factor leading to postoperative morbidity and mortality is low cardiac output. We studied the correlation between the comprehensive Aristotle score and cardiac output (CO) in infants after the Norwood procedure. METHODS AND RESULTS Respiratory mass spectrometry was used to continuously measure systemic oxygen consumption (VO(2)) in 22 infants for 72 hours postoperatively. Arterial, superior vena caval and pulmonary venous blood gases were measured at 2 to 4 hour intervals to calculate CO. The comprehensive Aristotle score was collected. Hospital mortality was 4.5%. The comprehensive Aristotle score ranged from 14.5 to 23.5 and negatively correlated with CO (P = 0.027). Among the patient-adjusted factors, myocardial dysfunction (n = 10), mechanical ventilation to treat cardiorespiratory failure (n = 9) and atrioventricular valve regurgitation (n = 4) (P = 0.01) negatively correlated with CO (P = 0.06 to 0.07). Aortic atresia (n = 9) was associated with a lower CO (P = 0.01) for the first 24 hours which linearly increased overtime (P = 0.0001). No correlation was found between CO and other factors (P > 0.3 for all). CONCLUSIONS Comprehensive Aristotle score significantly negatively correlates with CO after the Norwood procedure. A preoperative estimation of the comprehensive Aristotle score, particularly in association with myocardial dysfunction, mechanical ventilation to treat cardiorespiratory failure, atrioventricular valve regurgitation and aortic atresia may help to anticipate a high postoperative morbidity with low cardiac output syndrome.

Kaposiform Hemangioendothelioma Presenting Antenatally With a Pericardial Effusion

We describe an infant presenting with fetal pericardial effusion requiring in utero pericardiocentesis. Important postnatal clinical features included recurrent pericardial effusion, progressive stridor, thrombocytopenia, anemia, and a mediastinal mass surrounding the heart and coronary arteries. Investigations and management consisted of repeat pericardiocentesis, platelet and red blood cell transfusions, laryngoscopy, creation of a pericardial window, and biopsy of the mediastinal mass. Diagnosis was made of Kaposiform hemangioendothelioma surrounding the base of the heart, trachea, and esophagus as well as Kasabach-Merritt phenomenon. The infant responded well to treatment with vincristine and prednisone.

Critical care outcomes in pulmonary atresia and intact ventricular septum undergoing single-ventricle palliation

OBJECTIVE To examine early outcomes for pulmonary atresia with intact ventricular septum undergoing single-ventricle palliation and to determine risk factors for mortality. DESIGN Retrospective observational study. SETTING Tertiary paediatric critical care unit. INTERVENTION Risk factors for mortality were sought for infants after the primary intervention whether surgical shunt or ductal stent. MEASUREMENTS AND MAIN RESULTS We reviewed outcomes of 19 infants with pulmonary atresia with intact ventricular septum undergoing single-ventricle palliation between July, 2000 and July, 2008. Echocardiograms, cardiac catheterisation findings, anaesthesia, and critical care management, as well as autopsy reports were reviewed. We modelled survival after surgery and looked for predictors of early mortality. A total of 19 infants underwent single-ventricle palliation and seven of these died. The risk of death was increased by a lower arterial pH at induction of anaesthesia (p = 0.01), a lower systolic blood pressure (p = 0.01), and technical problems during surgery (p = 0.03). On admission to the critical care unit, a lower mixed venous saturation (p = 0.02) and presence of tachyarrhythmia (p = 0.02) were associated with the need for mechanical support within the first 48 hours. CONCLUSIONS There is a high early mortality for those who undergo single-ventricle palliation. It is higher for those who are haemodynamically compromised before surgery; technical problems, and haemodynamic instability during surgery also increase mortality.