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Congenital long QT syndrome is a rare and serious disorder in children. In addition to the clinical and electrocardiographical diagnostic criteria, molecular biochemistry has identified six genes which are implicated in this pathology. Our study involved a retrospective analysis of 23 patients aged less than 21 with congenital long QT syndrome, followed up for an average of two years. Genotypes were obtained for all of the patients. There were unfortunately two deaths, one of which had a mutation in the SCN5A gene. The other patient had a double mutation of the SCN5A and KCNE2 genes. Symptomatic patients had QT and QTc intervals noticeably longer than the asymptomatic patients, although this difference was not shown to be significant. LQT3 patients as well as those with a double mutation were affected more severely because two of the three LQT3 patients and one of the two patients with a double mutation suffered a cardiac arrest. Three patients in our study showed no mutation. Nevertheless, two of them suffered a severe cardiac event. This confirms the limits of genetic diagnosis, which could be envisaged in all cases. All of the clinical and ECG data should be combined with the genetic analysis in order to confirm the diagnosis.

We describe in this article the recent data on the genetics of congenital heart defects (CHD) organised by type of CHD although each predisposing genetic factor is associated with a whole variety of CHD types. The recent progress resulting from animal models, molecular cytogenetics and CHD familial cases studies allow a better understanding of the determinism of CHD. This lead in term to improved counselling of parents of affected children and of CHD adults who would like to become parents. Nevertheless, more progress is needed to reach a better accuracy in prediction.

Coronary disease of the transplanted heart is the principal cause limiting long-term survival of patients and grafts. In view of the invasive nature of coronary angiography, dobutamine echocardiography has been proposed as a non-invasive diagnostic method for this disease. The aim of this study was to determine the feasibility and reliability of this investigation in transplanted children. Twenty-one echoes were performed with dobutamine infusions in 17 patients transplanted at 10 months to 16.9 years of age (average 8.4 years), and followed up 1.1 to 10.1 years (average 4.4 years): 4 were on antihypertensive drugs but none were treated by betablockers. Dobutamine echocardiography was performed according to the standard protocol used in adults. The maximal level was attained in all cases. No major side effects were observed. The maximal heart rate attained 57 to 89% of the theoretical maximal rate, an increase of 44 to 184% compared with the basal heart rate. The maximal systolic blood pressure rose to 120 to 194 mmHg, an increase of 8 to 109% compared with resting values. The contractility scores and segmental contractile index were normal in 18 cases, abnormal at the maximal level in 2 cases (hypokinesia of segments 8 and 9 and akinesia of segments 10 and 16 with an index of 1.2), abnormal at the lowest levels (hypokinesia of segment 7 with an index of 1.1) and maximal level (hypokinesia of segments 1 and 7 with an index of 1.2) in one case. These results were concordant with coronary angiography performed within 2 to 8 days of echocardiography, and considered as the diagnostic investigation of reference (sensitivity 75%, specificity 100%, positive predictive value 100% and negative predictive value 93%). The authors conclude that dobutamine echocardiography is a non-invasive method easily performed with low risk in transplanted children but its diagnostic performance in coronary disease of the transplanted heart should be confirmed in larger studies.