Contraction Delay Research Articles

Wolff-Parkinson-White syndrome: Right ventricular precontracting area proved by cardiac catheterization

A case of Wolff-Parkinson-White syndrome studied by left and right heart catheterization and phonocardiography is presented. The electrocardiograms in a five year follow-up showed remarkable changes which are discussed. The phonocardiogram disclosed a double wave before the first heart sound but no splitting of the heart sounds. The right ventricular pressure tracing confirmed the existence of a precontraction area in the right ventricle. Left and right heart catheterization proved that there was no delay in the effective contraction of both ventricles.

Auscultatory and phonocar-diographic signs of ventricular septal defect with left to-right shunt.

Ventricular septal defect with low pulmonary vascular resistance and left-to-right shunt is well known to be closely associated with a pansystolic murmur caused by the regurgitant shunt of blood at high velocity across the defect. With very high flows a pulmonary ejection murmur is superimposed on the pansystolic murmur and is occasionally the only systolic murmur if the ventricular septal defect is so large that the velocity of the shunt is small. In two patients thought to have small ventricular septal defects the shunt murmur was confined to early systole, probably because the defect was in the muscular septum and was closed by systolic contraction of the ventricle. The second heart sound is abnormally widely split in the majority of patients, even with small defects. The mechanism is difficult to elucidate but there appears to be slight shortening of the left ventricular isometric time (early A 2 ) and delay in contraction of the right ventricle (late P 2 ). The splitting of the second sound is a useful way of differentiating the large defects with left-to-right shunt from the Eisenmenger group of large defects with equal pulmonary and systemic vascular resistances and a loud single second sound. The auscultatory differential diagnosis of ventricular septal defect is discussed.