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

THE SIGNS of ventricular septal defect depend on the size of the defect and the pulmonary vascular resistance, these factors determining the direction and degree of the shunt and producing the well-known variations in the characteristics of the systolic murmur. Abnormally wide splitting of the second heart sound is a feature of ventricular septal defect with left-to-right shunt which seems to have escaped general recognition, probably because the loud pansystolic murmur drowns aortic closure. We have investigated 23 subjects with isolated ventricular septal defect with left-to-right shunt and normal or slightly elevated pulmonary vascular resistance (aged 4 to 18 years, average 11 years), and have divided them into two groups: Group 1-niinimal defects as described by Roger (less than 0.5 cm. diameter; Wood et al., 19541) : these patients had a loud systolic murmur without evidence of ventricular hypertrophy, clinically or on the electrocardiogram, normal right-sided pressures and a normal x-ray appearance. Group 2-larger ventricular septal defects with moderate or large left-to-right shunts. The auscultatory and phonocardiographic differential diagnosis will be discussed and also the separation of these patients from the inoperable Eisenmenger group with high pulmonary vascular resistance and bidirectional shunts. Method Following clinical, electrocardiographic, and x-ray examination, each subject was investigated with phonocardiography by means of simultaneous recordings from different sites,2 before and after amyl nitrite inhalation,3 and a study was made of the effect of respiration on splitting of the second heart sound by a specially accurate time marker.4 The paper speed was 100 mm. per second, the photographic recorder responded well to frequencies up to 800 cycles, and measurements were made, during the expiratory and inspiratory phases of continued respiration, from the onset of electrical activation (QRS) to the onset of the first sound and to the onset of aortic (A,) and pulmonary (P2) components of the second sound. Carotid pulse tracings were taken in each subject by a method designed to correspond closely to a central aortic pulse, using an air-filled cuff and a linear manometer and amplifying system.5 6 Measurements were made from mitral closure (M1) to carotid rise (corrected for delay in the system by subtracting the A2-dicrotic notch interval) and were assumed to give an approximation to the isometric contraction time of the left ventricle. Measurements from the carotid rise to the dicrotic notch gave the ejection time of the left ventricle and each measurement was compared with the ejection time at …