Severity of the ductal shunt: a comparison of different markers

BACKGROUND

When the ductus arteriosus (DA) is patent, the ductal shunt is proportional to the ratio of left ventricular output (LVO) to systemic blood flow. Systemic blood flow can be estimated by measuring flow in the superior vena cava (SVC).

OBJECTIVE

To re-evaluate the accuracy of standard echocardiographic markers of patent ductus arteriosus (PDA) using LVO/SVC flow ratio.

METHODS

Prospective study. Preterm infants of 24-30 weeks gestational age and postnatal age less than 48 hours. The following echocardiographic criteria were measured: left atrial to aortic root ratio (LA/Ao); DA diameter by B mode and colour Doppler; mean and end diastolic flow velocity of the left pulmonary artery (LPA); LVO; SVC flow.

RESULTS

Twenty three preterm infants were enrolled (median gestational age 28 weeks (range 24-30), median birth weight 840 g (500-1440)). The DA was closed in eight (mean (SD) LVO/SVC 2.4 (0.3)) and open in 15 (mean (SD) LVO/SVC 4.5 (0.6)). An LA/Ao ratio > or =1.4, a DA diameter > or =1.4 mm/kg, and a mean and end diastolic flow velocity of LPA respectively > or =0.42 and > or =0.20 m/s identified an LVO/SVC > or =4 with a sensitivity and a specificity above 90%.

CONCLUSION

This study indicates that LA/Ao ratio, DA diameter, and mean and end diastolic flow velocity of the LPA are accurate markers of PDA. These standard echocardiographic variables are easy to measure and need less skill and resources than direct measurements of ductal shunt.

Myocardiopathie rythmique de l’enfant : un diagnostic difficile mais une forme curable de dysfonction ventriculaire gauche

Tachycardia-induced cardiomyopathy is a reversible left ventricular dysfunction caused by cardiac arrhythmia. Because of its reversibility, a correct diagnosis and treatment are necessary. The aim of our study was to precise the diagnostic procedures of the tachycardia-induced cardiomyopathy and to study the left ventricular function after the correction of the arrhythmia.

PATIENTS AND METHODS

A retrospective study done between 1992 and 2001. Children studied were followed-up for: an idiopathic form of cardiomyopathy, in which the etiological research showed a cardiac arrhythmia; a cardiac arrhythmia associated to a cardiomyopathy. An electrocardiogram recorded the cardiac arrhythmia. The left ventricular function was evaluated by an echocardiography before and every month after the correction of the cardiac arrhythmia.

RESULTS

Twelve children were included, ages ranged from 2 months to 15 years (median 11 years). Four patients presented a cardiac insufficiency associated to arrhythmia; three followed-up for an arrhythmia developed a cardiomyopathy; five whose cardiac arrhythmia was not easy to demonstrate had an idiopathic form of cardiomyopathy. The Wilcoxon test showed a significant amelioration (P < 0.01) of the left ventricular function after the correction of the cardiac arrhythmia.

CONCLUSIONS

Tachycardia-induced cardiomyopathy in children is curable and the diagnosis is quite difficult. Pediatricians and family doctors should try to look for specific signs of cardiac insufficiency or arrhythmia. Pediatric cardiologists should search a tachycardia-induced cardiomyopathy in every idiopathic form of cardiomyopathy.