Juan Alejos

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.

Diagnosis and treatment of pediatric viral myocarditis.

Acute myocarditis is characterized by the rapid development of life-threatening congestive heart failure and arrhythmias. Although the initial stages of this disorder apparently result from direct cytopathic effects on the atrial and ventricular myocardium, later stages of progressive decompensation may result from immune-mediated myocyte destruction. There has been recent improvement in understanding the role of this immunologic cascade. As a result, treatment now begins earlier in the course of the disease and can target both the virus and the immune response. Our ability to implement mechanical support in children as a bridge to transplant or recovery, even in children presenting in the final stages of their disease, has led to an improved outcome regarding morbidity and mortality.

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.

Diverse morphologic manifestations of cardiac allograft vasculopathy: A pathologic study of 64 allograft hearts

BACKGROUND Cardiac allograft vasculopathy (CAV) is a major limitation to the long-term success of cardiac transplantation. Although there are published descriptions of the lesions, there have been no studies delineating the pathology of CAV in a large series of patients who underwent retransplantation for CAV. METHODS We reviewed archival records and microscopic sections of surgically explanted hearts from 64 patients who underwent cardiac retransplantation: 54 adults (18 to 70 years old) and 10 children (3 to 15 years old). Vascular lesions were categorized as showing intimal fibromuscular hyperplasia, atherosclerosis and/or inflammation. The degree of luminal narrowing was estimated from gross descriptions and microscopic sections. RESULTS In total, 75% of hearts had evidence of acute cellular rejection, mostly mild. Intramyocardial arteries showed primarily intimal fibromuscular hyperplasia and inflammation with no atheromas present. Large and branch epicardial coronary arteries were narrowed in at least one artery of all hearts. Lesions in the epicardial coronary arteries were composed of intimal fibromuscular hyperplasia, atherosclerosis and/or inflammation affecting one or more vascular layers (intima, media and adventitia). Severe CAV with >75% luminal narrowing was seen in the LAD in 17% of hearts, the LCx in 17% and the RCA in 22% of hearts. Two hearts had severe narrowing of the left main coronary artery. Nineteen arteries had luminal thrombi. All hearts had narrowing of smaller epicardial branch coronary arteries that was often severe. Atheromas were present in arteries of adults and children; thus, not all atheromas could be considered pre-existing prior to transplantation. Both arteries and veins showed intimal hyperplasia and inflammation. CONCLUSIONS CAV is a pathologically multifaceted disorder that affects large and small epicardial coronary arteries of adults and children, with different types of lesions: intimal fibromuscular hyperplasia; atherosclerosis; and/or inflammation (vasculitis). Therapies to address this disease must take into account the protean nature of the vascular lesions.

Outcomes of Pediatric Patients With Hypertrophic Cardiomyopathy Listed for Transplant

BACKGROUND The course of pediatric hypertrophic cardiomyopathy (HCM) is variable, and the indications for heart transplantation (HTx) are ill defined. This study investigated outcomes and risk factors for adverse outcomes after listing for HTx. METHODS A multicenter, event-driven data registry of patients aged < 18 years listed for HTx between January 1993 and December 2007 was used. RESULTS During the study period, 3,147 children were listed for HTx (mean age, 7.6 +/- 0.8 years). Of l,320 with CM at listing, 77 (6%) had HCM (61% boys; 79% white); 59% were United Network of Organ Sharing (UNOS) status I, 30% were receiving inotropes, 27% were ventilated, and 8% required extracorporeal membrane oxygenation. Arrhythmia had occurred in 27%, and 14% had failure to thrive. Within 1 year, 65% underwent HTx. Overall, 25 patients died after listing: 11 (14%) while waiting and 14 of 49 (29%) after HTx. Pre-HTx survival was lower for those listed at age < 1 year (p = 0.0005). Risk factors for death after listing included UNOS status 1 (p = 0.01) and younger age (relative risk, 2.3; p = 0.001). Late (10-year) survival after HTx for HCM patients was 47% vs 63% for non-CM patients within the database. CONCLUSIONS Children with HCM listed for HTx age < 1 year and UNOS status 1 have the highest mortality awaiting HTx. A more rigorous identification of additional risk factors should be performed to better define timing of listing and which patient sub-group may derive optimal benefit from HTx.

Effectiveness of the bidirectional Glenn shunt procedure for volume unloading in the single ventricle patient.

Abstract The decisions for timing and type of surgical intervention in patients with a single ventricle who have significant risk factors for poor Fontan outcome are a continuing challenge. Often, these patients may be deferred further surgical intervention for a prolonged period of time because of their risk factors. The bidirectional Glenn shunt has been shown to be a very useful staging procedure for such patients.1 It offers the benefit of providing flow to the pulmonary arteries without adding additional volume burden to the ventricle. In this study we retrospectively analyzed both the volume and mass changes that occur perioperatively when patients with single ventricle physiology undergo a bidirectional Glenn shunt procedure, as well as the effects of age, preoperative oxygen saturation, preoperative hemoglobin, atrioventricular valve regurgitation, and mild systemic outflow obstruction upon these changes.

Anomalous origin of the left main pulmonary artery from the ascending aorta associated with Digeorge syndrome

We place on record 2 infants with the DiGeorge syndrome and anomalous origin of the left pulmonary artery from the ascending aorta. We postulate that: (1) embryogenesis of anomalous origin of the left pulmonary artery from the ascending aorta might be due to the persistent fifth aortic arch connecting both arterial systems; (2) an anomalous pulmonary artery arising from the ascending aorta is part of the aortic arch abnormality accompanied by normal conotruncal septation; and (3) in the DiGeorge syndrome, cardiac anomalies that originate from the conotruncus or aortic arch, or both, may have the same embryologic mechanisms.

B-type natriuretic peptide in children after cardiac transplantation

BACKGROUND The normal B-type natriuretic peptide (BNP) concentration and the significance of increased BNP concentration in children after orthotopic heart transplant (OHT) remain unknown. We sought to determine plasma BNP concentrations in relation to post-transplant time and to explore factors associated with increased BNP in pediatric OHT recipients. METHODS We obtained plasma BNP concentrations in 44 pediatric patients at 1 to 171 months after OHT. All patients underwent endomyocardial biopsies and echocardiography. We analyzed the association between BNP and post-transplant time, as well as the association between BNP concentration and left ventricular end-diastolic dimension (LVEDD) after transplantation. RESULTS The age of study patients ranged from 0.9 to 21.2 years (mean, 11.4 +/- 6.2 years; median, 10.5 years). We evaluated BNP concentrations immediately after transplantation. The mean BNP concentration decreased exponentially to 100 pg/ml by 14 weeks after OHT. Although BNP concentration relative to time after OHT varied among individuals, all patients with multiple measurements showed predictable rates of decrease. This decrease in BNP concentration was not associated with changes in LVEDD. CONCLUSIONS Plasma BNP concentration was elevated in children after OHT and decreased exponentially in time to 100 pg/ml by 14 weeks after OHT. The decrease in BNP concentration was unrelated to left ventricular dimension.

Marked left ventricular hypertrophy in children on tacrolimus (FK506) after orthotopic liver transplantation.

Although the cardiac effects of tacrolimus (FK506) have not been well documented, clinical cases of children on FK506 who developed hypertrophic obstructive cardiomyopathy have been reported. We report 2 cases of marked concentric hypertrophy of the left ventricular myocardium found at autospy in children on FK506.