Kenneth G. Warner

Expanding the indications for pulmonary valve replacement after repair of tetralogy of fallot

BACKGROUND Insertion of a competent pulmonary valve has been advocated to reduce right ventricular volume overload associated with pulmonary regurgitation (PR) after repair of tetralogy of Fallot. However the indications, proper timing, and long-term benefits of restoring pulmonary valve function remain controversial. METHODS Thirty-six patients (aged 15.2 +/- 9.2 years) underwent pulmonary valve implantation (31 homografts, 5 heterografts) 12.2 +/- 6.9 years after tetralogy repair. Additional surgical procedures included pulmonary artery augmentation (n = 14), closure of septal defects (n = 10), and cryoablation and endocardial resection of ventricular tachycardia (n = 2). RESULTS All patients have had clinical improvement in their exercise capacity. Preoperative and postoperative bicycle ergometry tests in 6 patients demonstrated significant improvement in the percent of predicted peak workload (68.5% +/- 19.8% to 80.7% +/- 17.4%, p < 0.015). One midterm death occurred in a 38-year-old patient with a history of ventricular tachycardia who died suddenly 2 years after pulmonary valve insertion. Postoperative echocardiographic measurements were available in 34 patients at a mean follow-up of 5 years. There was a 30% reduction in right ventricular end-diastolic diameter indexed to body surface area after surgery (30.1 +/- 10.2 to 18.6 +/- 6.0 mm/m(2), p < 0.0001). Two patients required conduit replacements at 1 and 9 years postoperatively. CONCLUSIONS Timely insertion of a competent pulmonary valve in children, adolescents, and young adults with significant PR after tetralogy of Fallot repair results in subjective and objective improvement in exercise capacity and is associated with reduction in right ventricle size.

Repair of coarctation of the aorta during infancy minimizes the risk of late hypertension.

BACKGROUND Recent surgical reports on coarctation of the aorta have primarily focused on the relative merits of various operative techniques. However, appropriate timing for elective repair remains unclear. METHODS In a retrospective analysis we examined the surgical outcomes in 176 consecutive patients undergoing repair of coarctation of the aorta in our institution over a 25-year period. Ninety-nine percent of the patients had follow-up for a median of 7.5 years. RESULTS A total of 13 patients have died (7.4% overall mortality). Nine of these patients had associated complex intracardiac anomalies. There was no mortality in the 113 patients with isolated coarctation. Residual or recurrent coarctation occurred in 27 patients (15.3%). The age at operation and the type of surgical repair did not have an effect on the incidence of recurrence. Persistent or late hypertension was identified in 18 of the 107 patients who have been followed up for more than 5 years (16.8%). A total of 48 patients operated on during infancy have been followed up for more than 5 years. Only 2 have developed late hypertension (4.2%). Both of these patients had recurrence. In contrast, 16 of the 59 patients operated on after a year of age had late hypertension (27.1%). CONCLUSIONS To minimize the risk of persistent hypertension, elective repair of coarctation should be performed within the first year of life.

Clinical benefits of endoscopic vein harvesting in patients with risk factors for saphenectomy wound infections undergoing coronary artery bypass grafting

OBJECTIVE The influence of endoscopic harvesting techniques on the prevalence of leg-wound complications after coronary artery bypass grafting remains to be defined for patients at high risk for the development of wound infections. METHODS Among 1473 patients undergoing coronary artery bypass grafting who had the saphenous vein harvested by either a continuous incision or skip incisions leaving intact skin bridges, we determined the prevalence of wound infections to be 9.6%. The following variables were entered into logistic regression analysis to identify significant risk factors that might be predictive of wound infection: diabetes, peripheral vascular disease, obesity, renal failure, steroid use, age, sex, and type of closure. We then prospectively randomized 132 patients found to be at high risk of wound infection to either endoscopic vein harvesting or a continuous open incision. RESULTS Univariate analysis showed female sex (P =.04), diabetes (P <.001), and obesity (P <.001) to be predictors of wound infection. In a multivariate model diabetes (P =.02) and obesity (P =.001) were independent predictors. In patients at high risk, the prevalence of wound infection was 4.5% for the endoscopic group versus 20% for the open group (P =.01). Vein procurement time was greater in the endoscopic group (65 minutes vs 32 minutes, P <.001), as was the number of vein repairs required (2.5 vs 0.6, P <.001). CONCLUSION The use of endoscopic vein harvesting decreases the prevalence of postoperative leg-wound infections in high-risk patients with diabetes and obesity. Whether this translates into an economic benefit that justifies the additional cost of that technology requires further analysis.

Three-dimensional echocardiographic analysis of valve anatomy as a determinant of mitral regurgitation after surgery for atrioventricular septal defects

Mitral regurgitation (MR) is a significant complication after atrioventricular septal defect (AVSD) surgery. The relation of the valve leaflet morphology and the MR mechanism remains a conundrum. Two-dimensional echocardiography depicts leaflet edges, whereas volume-rendered 3-dimensional echocardiography provides direct visualization of the surface areas of the mitral valve leaflets. This study examines the relation of mitral valve anatomy as determined by 3-dimensional echocardiography with MR origins in patients after AVSD repair. Twenty-seven patients with AVSD surgery and Doppler color MR were prospectively enrolled (median age was 5 years and 16 patients had Down syndrome). Doppler color flow imaging of the MR jet and 3-dimensional echocardiography of the mitral valve were performed with a probe in the transthoracic or transesophageal position. Enface 3-dimensional views of the mitral valve from the left atrium were reconstructed. Analysis of the 3-dimensional data was possible in 21 of the 27 patients. Mean area ratios of the 3 mitral leaflets were calculated (superior 40 +/- 7%, inferior 35 +/- 5%, mural 25 +/- 6%). Both intra and interobserver variability on the area measurements were <5%. In 12 patients (group 1) the jet appeared to emanate medially from the region of coaptation of the superior and inferior components of the anterior leaflet. In 9 patients (group 2) the jet emanated more laterally from the region toward the mural leaflet. The area ratios of the inferior leaflet were 32 +/- 4% in group 1 and 38 +/- 6% in group 2 (p = 0.02). The area ratios of the mural leaflet were 28 +/- 5% in group 1 and 21 +/- 5% in group 2 (p = 0.007). The superior leaflet area ratio was not different in groups 1 and 2, 40 +/- 9% and 41 +/- 6%, respectively. Three-dimensional echocardiography provides new insight into the anatomic determinants of MR following AVSD surgery.

Balloon Angioplasty of Native Coarctation of the Aorta in Infants and Neonates: Is It Worth the Hassle?

Abstract. Balloon angioplasty (BA) for native coarctation of the aorta (CA) in infants and neonates remains controversial with a high incidence of restenosis. The purpose of this study is to analyze our acute and midterm results for BA of native CA in infants and neonates and try to identify factors that may be predictive of outcome. Between September 1991 and June 1999, 17 patients with CA underwent BA at a median age of 3 months (range 2 weeks–9 months) and median weight of 4.8 kg (range 2.8–7 kg). Fourteen patients had discrete CA and 3 had tubular hypoplasia. All patients were hemodynamically stable prior to BA and no patients had critical coarctation requiring prostaglandin E1 infusion to maintain ductus arteriosus patency. Seven patients had other associated cardiac defects. All patients had significant initial improvement. The mean peak systolic gradient across the CA improved from 43 ± 15 mmHg to 10 ± 8 mmHg (p < 0.001), and the mean minimum diameter of the aortic lumen increased from 2.4 ± 0.9 mm to 5.2 ± 1.0 mm (p < 0.001). There was no mortality or major complication. At median follow-up interval of 2.7 years (0.15–7.75 years), 10 (59%) of 17 patients are clinically well and have an upper to lower limb systolic blood pressure difference of <20 mmHg. Seven (41%) of 17 patients developed significant restenosis (5 of these patients underwent repeat BA, which was successful in 3 patients). Four (24%) patients underwent surgical repair at a median age of 4.5 months (3–6.9 months) and a median time interval of 4 months (2–6.5 months) from the initial BA. All 3 patients with tubular hypoplasia type of CA underwent surgical repair. No patients developed aortic aneurysm following initial or repeat BA. All patients who underwent surgical repair were 1 month or less in age at the time of their initial BA. We conclude that BA of native CA in infants and neonates can be performed safely with low mortality and morbidity. It appears to offer the best results in patients who are older than 1 month with discrete CA and a well-developed aortic arch. Further restenosis of the discrete CA can be managed successfully by repeat BA.

New Insights and Observations in Three-Dimensional Echocardiographic Visualization of Ventricular Septal Defects Experimental and Clinical Studies

BACKGROUND The positions, sizes, and shapes of ventricular septal defects (VSDs) can be difficult to assess by 2-dimensional echocardiography (2DE). Volume-rendered 3-dimensional echocardiography (3DE) can provide unique views of VSDs from the left ventricular (LV) side, allowing complete assessment of their circumference and spatial orientations to other anatomic structures. METHODS AND RESULTS Seventeen experimentally created defects of various locations, sizes, and shapes were imaged and reconstructed in 9 explanted porcine hearts. From an en face projection, major and minor axis diameters of the defects were measured, and these data were compared with direct anatomic measurements. Optimal reconstructions of the VSDs were obtained in all heart specimens, accurately depicting their positions and shapes. The correlations between 3DE and anatomy for the VSD major and minor axis diameters were y=1.0x+0.3 (r=0.88, P<0.001) and y=1.0x-1.4 (r =0.89, P<0.001), respectively. Good agreement between the 2 methods was demonstrated for all measurements. Our experience from the in vitro model was then applied to patient studies. Optimal LV en face reconstructions were obtained in 45 of 51 patients, permitting detailed assessment of the positions, sizes, and shapes of the VSDs. In the 25 patients with comparative surgical measurements, the correlations between 3DE and surgery for the VSD major and minor axis diameters were y =0. 81x+2.1 (r=0.92, P<0.001) and y=0.73x+2.0 (r=0.91, P<0.001), respectively. Good agreement was demonstrated between measurements made by 3DE and those obtained at surgery. CONCLUSIONS 3DE provides excellent visualization of various types of VSDs. From an LV en face projection, the positions, sizes, and shapes of VSDs can be accurately determined. Such precise imaging will be beneficial for surgical and catheter-based closure of difficult perimembranous and singular or multiple muscular VSDs.

Intraoperative metabolic monitoring of the heart: II. Online measurement of myocardial tissue pH.

Under conditions of ischemia, the hydrogen ion [H+] accumulates in the myocardial tissue in proportion to the magnitude of the ischemic insult. The accumulation of [H+] is the result of both increased anaerobic production of [H+] secondary to decreased substrate and decreased washout of [H+] secondary to decreased coronary perfusion. The Khuri tissue pH electrode/monitoring system has been developed and validated over the past two decades. Its scientific basis and correlates have been established, and it is the only system that has been approved for use in humans. Myocardial tissue pH has been monitored in the anterior and posterior walls of the left ventricle in more than 700 patients undergoing major cardiac surgery. An understanding of the relationship between pH and temperature and between the pH and [H+] in tissues is important for the proper interpretation of the myocardial pH data generated in the course of an operation. Intraoperative monitoring of myocardial pH is the only modality available to the cardiac surgeon for online assessment and improvement of the adequacy of myocardial protection. By defining myocardial protection in terms of protection from myocardial tissue acidosis, this technology provides a new tool with which the comparative efficacy of the various myocardial protection techniques can be assessed. It also provides an online tool for assessing the adequacy of coronary revascularization, and has the potential of improving procedures and outcomes for off-pump coronary artery bypass grafting.

Immediate-early Gene Expression in Ovine Brain after Cardiopulmonary Bypass and Hypothermic Circulatory Arrest

Background Cardiopulmonary bypass (CPB) and hypothermic circulatory arrest (HCA) are associated with neurological injury. Altered immediate-early gene expression occurs rapidly in the brain in response to ischemia, hypoxia, and severe metabolic stress, which results in long-term changes in the molecular phenotype of neurons. This study determined the effects of CPB and HCA on the expression of the immediate-early gene c-fos. Methods Neonatal lambs were subjected to 2 h of CPB at 38 degrees Celsius (n = 4) or 60 min (n = 6), 90 min (n = 7), and 120 min (n = 6) of HCA at 15 degrees Celsius. One hour after terminating CPB at 38 degrees Celsius, the brains were analyzed for FOS-encoding mRNA and FOS-like immunoreactivity in the hippocampal formation. Other animals (n = 15), subjected to the same CPB and HCA protocol, were allowed to survive 3-5 days before their brains were examined for dead neurons. Results Minimal c-fos mRNA and FOS proteins were observed in neurons of animals subjected to normothermic bypass and of those that served as controls. Non-neuronal FOS proteins were observed in the choroid plexus, ependyma, and blood vessels at all times, including normothermic CPB, but not in the control animals without CPB. The magnitude of c-fos mRNA expression in hippocampal neurons increased directly with the duration of HCA. In contrast, expression of FOS proteins peaked after 90 min of HCA and declined significantly thereafter. Dead neurons were seen in surviving animals after 2 h of HCA only. Conclusions Cardiopulmonary bypass and HCA alter immediate-early gene expression in the brain. Translational processes are impaired after 120 min of HCA and correlate with neuron death in the hippocampus.

Fate of Mitral Regurgitation Following Repair of Atrioventricular Septal Defect

The purpose of this study was to evaluate the fate of mitral regurgitation (MR) following repair of atrioventricular septal defects (AVSDs). Echocardiograms of all survivors of isolated AVSD surgery between 1986 and 1996, who had had > or =2 postoperative color Doppler studies (39 patients), were reviewed. On each study, MR severity was graded on a 1+ to 4+ scale, based upon the size of the MR jet. Median age at surgery was 9 months (range 3 to 169); median age at postoperative follow-up was 45 months (range 3 to 107). Mild deterioration of mitral valve function was fairly common. MR severity increased by > or =1 grade in 16 patients (41%) during the course of the study. However, the deterioration in mitral valve function occurred primarily during the early postoperative time intervals. After the initial 32 postoperative months, MR worsened on only 4 occasions and in each instance worsened by only 1 grade. Deterioration to 4+ MR occurred in only 3 patients, and was not observed after the initial 30 postoperative months. Survival curve analysis predicted a 90% probability of not having severe (4+) MR after 30 months (lower 95% confidence bound: 80%). Postoperative MR remains fairly stable following AVSD repair. Serious deterioration is rare, especially after the initial 30 postoperative months.

Transcatheter retrograde radio-frequency perforation of the pulmonic valve in pulmonary atresia with intact ventricular septum, using a 2 French catheter

A neonate with pulmonary atresia with intact ventricular septum (PA/IVS) underwent successful retrograde transcatheter perforation of the pulmonary valve, using a 2 Fr radio-frequency catheter with subsequent anterograde balloon dilation of the valve. Due to persistent hypoxemia, the neonate underwent placement of a 4-mm modified Blalock-Taussig shunt. Transcatheter retrograde transductal perforation of the pulmonic valve in PA/IVS is feasible and may be a potential alternative to anterograde perforation.