Alvaro Galindo

Benefits of Early Surgical Repair in Fixed Subaortic Stenosis

OBJECTIVES We sought to determine whether early resection can improve outcome in fixed subaortic stenosis. BACKGROUND The diagnosis of subaortic stenosis (SAS) is often made before significant gradients occur. Whereas resection is the accepted treatment, it remains uncertain whether surgical intervention at this early stage can reduce the incidence of recurrence or influence the progression of aortic valve damage. METHODS Follow-up was available for 75 of 83 consecutive patients operated on for fixed SAS; the average duration of follow-up was 6.7 years. The lesion was discrete in 68 patients (91%) and of a tunnel type in 7, with associated ventricular septal defect in 28 (37%). All underwent transaortic resection. RESULTS There were no deaths. There were 18 recurrences of SAS in 15 patients (20%). Thirteen patients (17%) underwent 17 reoperations for recurrence or aortic valve disease. The cumulative hazard of recurrence was 8.9%, 16.1% and 29.4% +/- 2.3% (mean +/- SEM), and the hazard of events, including recurrence and reoperation, was 9.2%, 18.4% and 35.1% +/- 3.5% at 2, 5 and 10 years, respectively. Residual end-operative left ventricular outflow tract (LVOT) gradients (> 10 mm Hg, n = 8) and tunnel lesions were univariate predictors of recurrence (p = 0.0006 and p = 0.003, respectively). Multivariate predictors included higher preoperative LVOT gradient (p < 10(-4)) and younger patient age (p = 0.002). Only two recurrences (0.87 per 100 patient-years of follow-up) were noted in patients with a preoperative peak LVOT gradient < or = 40 mm Hg (n = 40), whereas higher gradients (n = 35) were associated with a greater than sevenfold recurrence rate (6.45 events per 100 patient-years, p = 0.002). The aortic valve required concomitant repair in 17 cases in the high gradient group (48.6%) but in only 8 in the low gradient group (20%, p = 0.018). Despite relief of the obstruction, progressive aortic regurgitation was noted at follow-up after 14 procedures in the high gradient group (40%) but after only 5 procedures in the low gradient group (12.5%, p = 0.014). CONCLUSIONS The data suggest that surgical resection of fixed subaortic stenosis before the development of a significant (> 40 mm Hg) outflow tract gradient may prevent recurrence, reoperation and secondary progressive aortic valve disease.

Use of assist devices and ECMO to bridge pediatric patients with cardiomyopathy to transplantation

BACKGROUND Pulsatile ventricular assist devices (VADs) are used to bridge adults with end-stage heart disease to transplantation. A combination of external implantable pulsatile and continuous-flow external mechanical support now can be used to bridge pediatric patients with end-stage cardiomyopathy to orthotopic heart transplantation (OHT). METHODS We reviewed consecutive pediatric patients with cardiomyopathy (n = 28) who required mechanical cardiac support from July 1995 to February 2001. All were OHT candidates with severe hemodynamic compromise despite maximal medical support. We excluded from this series patients who had undergone cardiotomy. RESULTS Nineteen patients received support from external continuous-flow devices, either with extracorporeal membrane oxygenation or with centrifugal VADs, and 9 patients received pulsatile support. Nineteen of 28 (68%) patients were successfully bridged to transplant (17) or weaned (2) from their devices after recovery. Of the patients successfully bridged to transplant or recovery, 89% are alive to date. Univariate analysis revealed that a lower bilirubin concentration after 2 days of support was associated with a favorable outcome (p = 0.006). As expected, the patients with pulsatile VADs had significantly higher rates of extubation and oral feeding. CONCLUSION Pulsatile and continuous-flow devices can complement each other to significantly extend the lives of a wide range of pediatric patients with severe cardiomyopathies.

Abnormal dynamic cardiorespiratory responses to exercise in pediatric patients after Fontan procedure

OBJECTIVES Novel protocols were used to focus on dynamic cardiorespiratory function during submaximal exercise and on the recovery from 1-min pulses of exercise in children who had undergone Fontan corrections for single-ventricle lesions. BACKGROUND Particularly in children, maximal oxygen uptake (VO2max), which is commonly used to assess the functional capability of patients after the Fontan procedure, is highly effort dependent and not physiologic and leads to uncomfortable metabolic and cardiorespiratory stress. Alternative approaches include the measurement of dynamic responses during progressive exercise and recovery after short bursts of exercise. These strategies yield mechanistic insight into cardiorespiratory impairment and can be used to gauge limitations in daily life activity. METHODS Sixteen patients (mean [+/-SD] age 12.2 +/- 2.4 years; 9 boys) and 10 age-matched control subjects (mean age 12.2 +/- 2.4 years; 6 boys) performed two separate cycle ergometer tests in which gas exchange was measured on a breath by breath basis: 1) Progressive exercise was used to determine the dynamic relation among VO2, carbon dioxide production (VCO2), ventilation (VE), heart rate (HR) and work rate (WR). 2) A 1-min constant WR test was used to determine the recovery time for gas exchange and HR. RESULTS Peak VO2 and anaerobic threshold were reduced in patients who underwent the Fontan procedure compared with control subjects by 57% and 52%, respectively (p < 0.001). Dynamic relations during progressive exercise--deltaVO2/deltaHR and deltaVO2/deltaWR--were decreased (p < 0.001) and deltaVE/deltaVCO2 was increased (p < 0.005) in the Fontan group patients. Recovery times for HR and VO2 were prolonged in the Fontan group patients by 154% and 69%, respectively (p < 0.01). CONCLUSIONS The results demonstrate that submaximal gas exchange responses to progressive exercise and recovery times after brief high intensity exercise are abnormal in patients after the Fontan procedure. These observations complement the findings of reduced VO2max observed here and by others. We speculate that the mechanisms for these responses are related to 1) a pervasive reduction in stroke volume for both low and high intensity exercise, 2) an abnormal linkage of ventilation to tissue carbon dioxide production, and 3) increased dependence on anaerobic metabolism in skeletal muscles. The prolonged recovery of HR and VO2 provides a possible mechanism for reduced physical activity.

Factors influencing survival in patients undergoing the bidirectional Glenn anastomosis

The bidirectional Glenn anastomosis (BGA) has long been used as a surgical intervention for patients with single ventricle physiology. Initially, this procedure was the final stage in palliation and was performed in older children. Eventually, as the Fontan procedure came to be used as a method to separate circulations, the Glenn procedure was performed as an intermediate step. Over time, the BGA was performed as an alternative for patients who were considered to be at high risk with the Fontan procedure. Between January 1, 1988, and January 1, 1994, 129 patients underwent BGA at the University of California-Los Angeles. These patients were reviewed retrospectively, including clinic visits, catheterization, and echocardiographic information. The overall survival rate was 87% (112 of 129 patients). The average length of follow-up was 27 months. This information was then analyzed by univariate and multivariate analysis. Several factors were related to failure in patients who underwent BGA including pulmonary artery pressure, systemic right ventricle, and presence of anomolous pulmonary venous drainage and heterotaxy syndrome.

Bubble contrast echocardiography in detecting pulmonary arteriovenous shunting in children with univentricular heart after cavopulmonary anastomosis.

OBJECTIVES We sought to compare bubble contrast echocardiography and pulmonary angiography in detecting pulmonary arteriovenous malformation (PAVM) in children with cavopulmonary anastomosis (CPA), and to examine anatomic and physiologic variables associated with the development of PAVM. BACKGROUND Development of PAVM in patients with CPA may cause profound cyanosis. Pulmonary arteriovenous malformation has been traditionally diagnosed by pulmonary angiography with reported incidence of 20% to 25% in patients with CPA. METHODS Fourteen patients (age 1.1 to 12.6 years) with any forms of CPA and normal pulmonary venous drainage formed the study population. All patients underwent cardiac catheterization and pulmonary angiography. Bubble contrast echocardiographic studies were performed with injection of 10 ml of agitated saline solution into branch pulmonary arteries. Transthoracic echocardiograms using an apical view were performed to assess the appearance of bubble contrast in the systemic ventricles. We compared the results of pulmonary angiograms and contrast echocardiograms, and findings of contrast echocardiograms between lungs with hepatic venous blood flow and lungs without hepatic venous blood. RESULTS Ten of the 14 patients (71%) had positive contrast echocardiographic studies, compared with three (21%) detected by pulmonary angiograms (p = 0.01). No difference was found in pulmonary artery pressure, transpulmonary gradient or presence of heterotaxy syndrome between patients with positive contrast echocardiographic studies and patients with negative studies. However, patients with positive contrast echocardiograms tended to have lower oxygen saturation (81%) and higher hemoglobin (16.4 g/dl) compared with patients with negative studies (88% and 14.7 g/dl, p = 0.10 and p = 0.18 respectively). Patients with Glenn shunt or unidirectional Fontan had higher incidence of PAVM (10/11) compared with patients with classic or lateral tunnel Fontan (0/3, p = 0.01). All 12 lungs with no perfusion of hepatic venous blood had positive contrast echocardiographic studies. Lungs with no hepatic venous blood flow were more likely to develop PAVM compared with lungs with hepatic venous blood flow (12/12 and 3/16 respectively, p < 0.01). CONCLUSIONS Bubble contrast echocardiography is more sensitive in detecting PAVM compared with pulmonary angiography. The prevalence of PAVM in patients with CPA may be much higher than what had been reported previously. Lungs with no hepatic venous blood flow are more likely to develop PAVM than lungs with hepatic venous blood flow.

Modification of the Fontan Procedure Superior Vena Cava to Left Pulmonary Artery Connection and Inferior Vena Cava to Right Pulmonary Artery Connection With Adjustable Atrial Septal Defect

BACKGROUND A modification of the Fontan procedure with unidirectional cavopulmonary connection is described in which the superior vena cava (SVC) is connected to the left pulmonary artery (PA) and the inferior vena cava (IVC) is connected to the right PA via a lateral tunnel with a snare-controlled, adjustable atrial septal defect (ASD). This allows matching of the SVC and IVC flows with the lung of appropriate size. The obligatory left Glenn shunt provides an adequate arterial oxygen saturation, and the elevation in SVC pressure is well tolerated. The adjustable ASD allows selective decompression of the IVC that maintains cardiac output and reduces fluid accumulation in the serous cavities. METHODS AND RESULTS Since March 1992, we have performed this procedure in 18 patients. There were 17 children and 1 adult. Median age was 3 years and 9 months (range, 13 months to 36 years). Six patients had been staged with a previous bidirectional Glenn shunt. Preoperative cardiac catheterization revealed a PA pressure of 13 +/- 2 mm Hg and a transpulmonary gradient of 5 +/- 3 mm Hg. Ventricular function was satisfactory in all patients. At the completion of bypass, the pressures in the SVC and IVC were 16 +/- 4 mm Hg and 10 +/- 3 mm Hg, respectively (P < .01). The left atrial pressure was 6.0 +/- 3.0 mm Hg and the arterial O2 saturation on 100% oxygen was 93 +/- 3%. There was one death as a result of intractable atrial arrhythmias. The remaining 17 patients had a mean hospital stay of 9.7 days (6 to 18 days). The length of pleural drainage was 7 +/- 3 days. The ASD was adjusted in 11 patients before discharge. Oxygen saturation at discharge was 85.4 +/- 4%. Nine patients had repeat catheterization. The ASD was completely closed in 6 patients, an average of 2.5 months after surgery (range, 3 weeks to 5 months). After ASD closure, the arterial oxygen saturation was 96 +/- 3%, and the SVC and IVC pressures were both 13 +/- 3 mm Hg. CONCLUSIONS The Fontan procedure with unidirectional cavopulmonary connection and adjustable ASD has several advantages that may reduce mortality and morbidity for the high-risk Fontan candidate.

Use of OKT3 for acute myocarditis in infants and children

Acute viral myocarditis triggers an autoimmune phenomenon that aggressive immunosuppressive therapy with monoclonal OKT3 may suppress. We treated 5 patients, aged 15 months to 16.5 years, who had acute viral myocarditis and left ventricular ejection fraction (LVEF) of 5% to 20%, with a combination immunosuppressive regimen that included OKT3, intravenous immunoglobulin, methylprednisone, cyclosporine, and azathioprine. Within 2 weeks of therapy, all patients demonstrated normalization of LVEF to 50% to 74%, and on mid-term follow-up, we have found no recurrence of heart failure or progression to dilated cardiomyopathy. In patients with severe acute myocarditis, aggressive immunosuppressive regimen based on OKT3 is safe and may inhibit or reverse the immune response, resulting in dramatic improvement in myocardial function.

Effect of late postoperative atrial septal defect closure on hemodynamic function in patients with a lateral tunnel fontan procedure

OBJECTIVES The aim of this study was to evaluate prospectively the effect of late atrial septal defect closure on cardiac output and oxygen delivery in patients who have undergone the Fontan procedure. BACKGROUND An adjustable atrial septal defect is incorporated in patients undergoing the Fontan procedure who have increased pulmonary vascular resistance or poor ventricular function, or both. After the Fontan procedure, the atrial septal defect is test occluded. Patients with mean right atrial and pulmonary artery pressures > 15 mm Hg are discharged with the atrial septal defect open. METHODS Twelve patients (20 months to 12 years old) underwent evaluation and closure of the atrial septal defect at a mean interval of 3.8 months (range 1 to 18) after the Fontan procedure. Each patient underwent full right and left heart catheterization. Cardiac output was obtained using the cine-volume method. The study included six patients with a high transpulmonary gradient or poor ventricular function preoperatively, or both (high risk group) and six who had only borderline increased pulmonary vascular resistance (low risk group). Patients in both groups had a mean right atrial pressure > 15 mm Hg when the atrial defect was test occluded in the first week after the Fontan procedure. RESULTS All results are given as mean value +/- SD. Ventricular end-diastolic pressure was significantly lower (p = 0.03) with the atrial septal defect open in low risk patients (6 +/- 3 mm Hg) than in high risk patients (10 +/- 3 mm Hg). With the atrial septal defect open, low risk patients had a significantly higher (p = 0.04) cardiac index (4.87 +/- 0.81 liters/min per m2) than the high risk patients (3.96 +/- 0.47 liters/min per m2). There was no significant difference (p = 0.14) in cardiac index between the two groups with occlusion of the atrial septal defect. Oxygen delivery was also significantly higher (p < 0.05) with the atrial septal defect open in low risk patients (836 +/- 99 ml/min per m2) than in high risk patients (704 +/- 106 ml/min per m2). There was no significant difference (p = 0.89) in oxygen delivery between the two groups with occlusion of the atrial septal defect. With the atrial septal defect open, the interatrial gradient was not significantly different in low risk patients (4 +/- 1 mm Hg) from that in high risk patients (4 +/- 1 mm Hg). CONCLUSIONS These data show that an interatrial communication results in increased postoperative systemic perfusion and oxygen delivery in patients with good diastolic ventricular function after the Fontan procedure.

Selective anterograde coronary arteriography in neonates with d-transposition of the great arteries: accuracy and safety.

OBJECTIVES This study was designed to evaluate the accuracy and safety of selective anterograde coronary arteriography for the identification of the origin and branching pattern of the three main coronary arteries in neonates with d-transposition of the great arteries. BACKGROUND Definition of coronary artery anatomy is important in neonates with d-transposition of the great arteries who are considered for the arterial switch operation. Balloon occlusion aortography defines coronary artery anatomy in most but not all cases. We have described a technique for selective anterograde coronary arteriography. METHODS Between March 1987 and May 1991, 17 neonates underwent selective anterograde coronary arteriography and 29 patients had balloon occlusion aortography. After venous access was gained, a mesenteric catheter was used to engage the coronary ostia for contrast injection. All angiograms were reviewed by three independent observers and the coronary artery diagnoses were compared with operative findings. Complications with the catheterization procedure were also recorded. RESULTS The accuracy of defining coronary artery anatomy with selective anterograde coronary arteriography (98 +/- 2%) was significantly (p < 0.05) greater than that achieved with balloon occlusion aortography (69 +/- 6%). There were no deaths with catheterization in either study group. Morbidity was similar in the groups with balloon occlusion aortography (7%) and selective anterograde coronary arteriography (6%) (p > 0.05) and was related to transient bradycardia induced by catheter manipulation in the right ventricle. No patient in either study group experienced cardiac ischemia. CONCLUSIONS Selective anterograde coronary arteriography is an accurate and safe technique for the definition of coronary artery pattern in neonates with d-transposition of the great arteries.

Effects of Enalapril on Exercise and End Systolic Ventricular Wall Stress in The Fontan Patient. † 218

Effects of Enalapril on Exercise and End Systolic Ventricular Wall Stress in The Fontan Patient. † 218