Hot topics in tetralogy of Fallot.

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. We explore "hot topics" to highlight areas of emerging science for clinicians and scientists in moving toward a better understanding of the long-term management of patients with repaired TOF. From a genetic perspective, the etiology of TOF is multifactorial, with a familial recurrence risk of 3%. Cardiac magnetic resonance is the gold standard assessment tool based on its superior imaging of the right ventricular (RV) outflow tract, pulmonary arteries, aorta, and aortopulmonary collaterals, and on its ability to quantify biventricular size and function, pulmonary regurgitation (PR), and myocardial viability. Atrial re-entrant tachycardia will develop in more than 30% of patients, and high-grade ventricular arrhythmias will be seen in about 10% of patients. The overall incidence of sudden cardiac death is estimated at 0.2%/yr. Risk stratification, even with electrophysiologic testing and cardiac magnetic resonance, remains imperfect. Drug therapy has largely been abandoned, and defibrillator placement, despite its high risks for complications and inappropriate discharges, is often recommended for patients at higher risk. Definitive information about optimal surgical strategies for primary repair to preserve RV function, reduce arrhythmia, and optimize functional status is lacking. Post-operative lesions are often amenable to transcatheter intervention. In selected cases, PR may be treated with transcatheter valve insertion. Ongoing surveillance of RV function is a crucial component of clinical assessment. Except for resynchronization with biventricular pacing, no medical therapies have been shown to be effective after RV dysfunction occurs. In patients with significant PR with RV dilation, optimal timing of pulmonary valve replacement remains uncertain, although accepted criteria are emerging.

Warfarin Overdose in a Breast-feeding Woman.

We describe a case of a breastfeeding woman with an accidental warfarin overdose resulting in a markedly elevated prothrombin time. The breast-fed infant was evaluated and tested for ill effects. We discuss the use of warfarin while breast-feeding.

Outcome of pulmonary valve replacements in adults after tetralogy repair: a multi-institutional study.

OBJECTIVE: The purpose of this study was to assess the outcome of pulmonary valve replacement (PVR) in adults with moderate/severe pulmonary regurgitation after tetralogy repair, with particular emphasis on patient outcome, durability of valve repair, and improvement in symptomatology. DESIGN/SETTING/PATIENTS: The project committee of the International Society of Congenital Heart Disease undertook a retrospective multi-institutional analysis of PVR. Seven centers participated in submitting data on 93 patients >18 years of age who had the operation performed and follow-up obtained. The average age of PVR was 26+/- years (median 27 years). Time of follow-up after replacement was 3 years (range 4 days-28 years). OUTCOMES/MEASURES/RESULTS: Kaplan-Meier estimates of durability of PVR showed approximately 50% replacement at 11 years. There were two deaths at 6 and 12 months after valve replacement. Right ventricular (RV) size estimated by echocardiography from pre- to postoperative studies decreased in 81% (P < 0.001 testing for equal proportions), but RV systolic function increased in only 36% (P = 0.09). Ability index improved in 59% (P < 0.001) and clinical heart failure status improved in 57% with this problem before PVR. PVR did not improve arrhythmia status in a small group of patients. CONCLUSIONS: PVR is associated with low mortality, decrease in RV size and improvement in ability index, and uncertain effects on RV systolic function. Average valve durability was approximately 11 years. Criteria for PVR that will preserve RV function are not clearly identified, and management of these patients remains a difficult enterprise.

Dosing of clopidogrel for platelet inhibition in infants and young children: primary results of the Platelet Inhibition in Children On cLOpidogrel (PICOLO) trial.

BACKGROUND: Infants and young children with certain types of heart disease are at increased risk for thromboses. Clopidogrel 75 mg/d is used in adults to prevent thrombotic events. The dose to achieve similar platelet inhibition in children is unknown. The objectives of the present study were (1) to determine the dose of clopidogrel needed in infants and young children to achieve a mean 30% to 50% inhibition of 5-micromol/L ADP-induced platelet aggregation (ie, inhibition similar to that observed with 75 mg in adults) and (2) to assess the safety and tolerability of clopidogrel in infants and young children. METHODS AND RESULTS: We performed a prospective, multicenter, randomized, placebo-controlled trial evaluating the pharmacodynamics of clopidogrel in children (0 to 24 months) with a cardiac condition at risk for arterial thrombosis. Patients were randomized to clopidogrel versus placebo in a 3:1 ratio in 4 sequential groups (0.01, 0.10, 0.20, and 0.15 mg/kg) for > or = 7 and < or = 28 days. Platelet aggregation was assessed at baseline and steady state by light-transmission aggregometry. Of 116 patients enrolled, 92 (50% neonates, 50% infants/toddlers) were randomized, and 73 completed the study. A total of 79% of the randomized and treated patients were taking aspirin. Compared with placebo, clopidogrel 0.20 mg x kg(-1) x d(-1) resulted in a mean 49.3% (95% confidence interval 25.7% to 72.8%) inhibition of the maximum extent of platelet aggregation and a mean 43.9% (95% confidence interval 18.6% to 69.2%) inhibition of the rate of platelet aggregation. There was marked interpatient variability in the degree of platelet aggregation inhibition within each treatment-dose group and age group. No serious bleeding events occurred. CONCLUSIONS: Clopidogrel 0.20 mg x kg(-1) x d(-1) in children 0 to 24 months of age achieves a platelet inhibition level similar to that in adults taking 75 mg/d. Clopidogrel is well tolerated in infants and young children at this dose.

Congenitally corrected transposition of the great arteries: an update.

Congenitally corrected transposition of the great arteries is a rare condition in which systemic venous blood returns to normally positioned atria. However, the atria are connected to the opposite ventricle, right atrium to left ventricle, left atrium to right ventricle; so-called atrioventricular discordance. In addition, the ventricles are inverted (right to left change in position) and are connected to the opposite great artery, left ventricle to pulmonary artery, right ventricle to aorta; thus, forming ventricular-arterial discordance. The aorta is anterior and to the left of the pulmonary artery, L-transposed. Atrioventricular discordance plus ventricular-arterial discordance results in normal blood flow (ie, congenitally corrected). The right ventricle with the tricuspid valve is the systemic ventricle. Common associated conditions are ventricular septal defects (VSDs), pulmonary stenosis, and congenital heart block. Major issues related to management revolve around the status of the systemic right ventricle, which can develop dysfunction with increasing age and tricuspid regurgitation, which can increase in severity with age and contribute to ventricular dysfunction. One emerging treatment is the double switch operation. In patients with no pulmonary obstruction, it is possible to switch the systemic and pulmonary venous return using an atrial baffle procedure followed by an arterial switch procedure. This results in the anatomical left ventricle now functioning as the systemic ventricle. In those patients with associated pulmonary obstruction and a VSD, another type of double switch can be performed in which the left ventricle is tunneled through the VSD to the aorta, the right ventricle is connected to the pulmonary artery with a homograft or other conduit, and the atrial baffle procedure is performed. The most difficult challenge is choosing the patient who is a candidate for the double-switch operation and the timing of that operation, or the timing of a more classical operation for associated defects.

Clinical outcomes of palliative surgery including a systemic-to-pulmonary artery shunt in infants with cyanotic congenital heart disease: does aspirin make a difference?

BACKGROUND: Aspirin (ASA) often is used to prevent thrombosis in infants with congenital heart disease after placement of a systemic-to-pulmonary artery shunt, but its effect on outcomes is unknown. METHODS AND RESULTS: The present multicenter study prospectively collected data on 1-year postoperative rates of death, shunt thrombosis, or hospitalization age <4 months for bidirectional Glenn/hemi-Fontan surgery in 1004 infants. The use and dose of ASA were recorded. Kaplan-Meier event rates were calculated for each event and the composite outcome, and a Cox regression model was constructed for time to event. Model terms were ASA use and type of surgery, with adjustment for age at surgery. Diagnoses were hypoplastic left heart syndrome (n=346), tricuspid atresia (n=103), tetralogy of Fallot (n=127), pulmonary atresia (n=177), heterotaxy syndrome (n=38), and other (n=213). There were 344 shunts placed without cardiopulmonary bypass (closed shunt), 287 shunts with bypass (open shunt), 323 Norwood procedures, and 50 Sano procedures. Overall, 80% of patients received ASA. One-year postoperative events rates were high: 38% for the composite end point, 26% for death, and 12% for shunt thrombosis. After the exclusion of patients with early mortality, patients receiving ASA had a lower risk of shunt thrombosis (hazard ratio, 0.13; P=0.008) and death (closed shunt: hazard ratio, 0.41, P=0.057; open shunt: hazard ratio, 0.10, P<0.001; Norwood: hazard ratio, 0.34, P<0.001; Sano: hazard ratio, 0.68, P=NS) compared with those not receiving ASA. CONCLUSIONS: The morbidity and mortality for infants after surgical placement of a systemic-to-pulmonary artery shunt are high. ASA appears to lower the risk of death and shunt thrombosis in the present observational study.

Report of the Tennessee Task Force on Screening Newborn Infants for Critical Congenital Heart Disease.

A member of the Tennessee state legislature recently proposed a bill that would mandate all newborn infants to undergo pulse oximetry screening for the purpose of identifying those with critical structural heart disease before discharge home. The Tennessee Task Force on Screening Newborn Infants for Critical Congenital Heart Defects was convened on September 29, 2005. This group reviewed the current medical literature on this topic, as well as data obtained from the Tennessee Department of Health, and debated the merits and potential detriments of a statewide screening program. The estimated incidence of critical congenital heart disease is 170 in 100,000 live births, and of those, 60 in 100,000 infants have ductal-dependent left-sided obstructive lesions with the potential of presentation by shock or death if the diagnosis is missed. Of the latter group, the diagnosis is missed in approximately 9 in 100,000 by fetal ultrasound assessment and discharge examination and might be identified by a screening program. Identification of the missed diagnosis in these infants before discharge could spare many of them death or neurologic sequelae. Four major studies using pulse oximetry screening were analyzed, and when data were restricted to critical left-sided obstructive lesions, sensitivity values of 0% to 50% and false-positive rates of between 0.01% and 12% were found in asymptomatic populations. Because of this variability and other considerations, a meaningful cost/benefit analysis could not be performed. It was the consensus of the task force to provide a recommendation to the legislature that mandatory screening not be implemented at this time. In addition, we determined that a very large, prospective, perhaps multistate study is needed to define the sensitivity and false-positive rates of lower-limb pulse oximetry screening in the asymptomatic newborn population and that there needs to be continued partnering between the medical community, parents, and local, state, and national governments in decisions regarding mandated medical care.

Pregnancy outcomes after atrial repair for transposition of the great arteries.

Increasingly, women born with complete transposition of the great arteries who have undergone atrial repair by either the Senning or the Mustard procedure are reaching childbearing age. This study reports on pregnancy outcomes after the atrial repair of transposition of the great arteries. Record review and standardized questionnaires were used to ascertain the outcomes of 70 pregnancies reported in 40 women (36 Mustard procedures, 4 Senning procedures). Of the 70 pregnancies, 54 resulted in 56 live births, 10 in miscarriages, and 6 in therapeutic abortions. At pregnancy, 31 women were in New York Heart Association class I, 8 were in class II, and 1 was in class III. Thirty-nine percent of the infants were delivered prematurely and weighed 2,714 +/- 709 g; 28% were delivered by cesarean section, 8 for cardiac indications. Maternal complications included arrhythmias in 5 women and hemoptysis in 2 women. Heart failure occurred in 6 women, developing during the second and third trimesters. Postpartum cardiac events developed 2 to 9 days postpartum: heart failure in 5 women, atrial fibrillation in 1 woman, and decreased oxygen saturation due to a new atrial baffle leak in 1 woman. Severe right ventricular (RV) failure led to cardiac transplantation after delivery in 1 woman; another developed heart failure and then died suddenly 1 month after delivery. There was 1 late death, 4 years after the patient's last pregnancy. In conclusion, pregnancy after atrial repair carries a moderate degree of risk and should be undertaken with caution.

Clinical presentations of unoperated and operated adults with congenital heart disease.

The clinical presentation of adults with congenital heart disease (ACHD) is exceptionally diverse. Operated, unoperated acyanotic, and cyanotic patients often have similar physiologic characteristics, and thus shared clinical symptomatology. Five illustrative cases are included to highlight important considerations in the diagnosis and management of ACHD. This article focuses on epidemiology, natural history, clinical outcomes, and use of ancillary studies in commonly encountered cardiac defects.