Stephen S. Hirschfeld

The echocardiographic assessment of pulmonary artery pressure and pulmonary vascular resistance.

Serial assessment of the status of the pulmonary vascular bed requires repeat cardiac catheterization. We have demonstrated that right ventricular systolic time intervals (RVSTI) may be measured from the pulmonary valve echo. The right ventricular ejection time (RVET) and right pre-ejection period (RPEP) were measured in 45 normal patients. The RVET and RPEP decreased with increasing heart rate but increased with age. The RPEP/RVET, however, was uninfluenced by either age or heart rate. The RPEP/RVET was, therefore, determined from the pulmonary valve echo in 64 patients with congenital heart disease who underwent cardiac catheterization. Increased pulmonary artery diastolic pressure (PADP), pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (MPAP) resulted in an increased RPEP/RVET. The use of the RPEP/RVET permitted the serial echographic evaluation of the pulmonary vascular bed in selected patients; marked elevation of the ratio indicated the presence of pulmonary hypertension.

Measurement of right and left ventricular systolic time intervals by echocardiography.

One of the noninvasive methods of evaluating left ventricular performance is the measurement of left ventricular systolic time intervals (LVSTI). However, noninvasive measurement of right ventricular systole by this technique has been unreliable because of the inability to accurately time the onset of right ventricular ejection. Excellent correlation of LVSTI measured from the carotid pulse and those determined from the echocardiogram was demonstrated in 15 patients. STI of the right ventricle (RVSTI) were measured in a similar fashion from the pulmonary valve echo in 11 normal children. Right ventricular ejection time (RVET) was longer than left ventricular ejection time (LVET). Right ventricular pre-ejection period (RPEP) was shorter than left ventricular pre-ejection period (LPEP). In 15 children with transposition of the great arteries (TGA) the situation was reversed. RVET was shortened and RPEP was prolonged as the right ventricle contracted against systemic resistance; whereas, the LVET lengthened and LPEP shortened with ejection into a low pressure pulmonary circuit. Our studies in a total of 41 patients indicate that accurate, noninvasive measurement of right, as well as left, ventricular STI can be obtained with the use of echocardiography.

Assessment of the pulmonary vascular bed by echocardiographic right ventricular systolic time intervals.

SUMMARY Echocardiography was used to measure right ventricular systolic time intervals (RVSTI) in 85 normal children (group I) and in 229 patients undergoing cardiac catheterization (group II). Corrected right ventricular pre-ejection period (RPEPC) and right ventricular ejection time (RVETC) (based on regression analysis of group I) and RPEP/RVET were each correlated with pulmonary artery (PA) diastolic and mean pressures and pulmonary vascular resistance (PVR). The best correlation (0.83) was between a second degree polynomial of the RPEP/RVET and PA diastolic pressure. The RPEP/RVET allowed prediction of PA diastolic pressure within 10 mm Hg in 85% of the patients. The utility of RPEP/RVET was confirmed in sequential data of 22 patients, in whom alteration in RPEP/RVET accurately reflected the changing PA diastolic pressure. The RPEP/RVET could not be used to assess PA pressure in six patients with congestive cardiomyopathy nor in 18 patients with complete right bundle branch block (CRBBB).

Echocardiographic abnormalities in infants of diabetic mothers

In order to evaluate the presence of myocardial hypertrophy and/or abnormalities of postnatal cardiovascular adaptation, echocardiograms were performed on 34 infants of diabetic mothers. Based on cardiopulmonary assessment, the IDM were divided into three groups: Group I with congestive heart failure predominating: Group II with respiratory distress predominating: Group III asymptomatic. Hypertrophy of the interventricular septum and of the walls of left and right ventricles was frequently present in IDM: this change was most notable in association with clinical CHF. Six IDM, four of whom were found to have CHF, had additional echocardiographic signs of subaortic stenosis. All IDM had normal indices of left ventricular performance, despite the presence of CHE. In IDM with respiratory distress, the right ventricular pre-ejection period to ventricular ejection time ratio was elevated, suggesting an abnormality of the transitional pulmonary circulation. Poor maternal diabetes control and maternal systemic hypertension were closely correlated with evidence of myocardial hypertrophy in the infants.

Concealed left atrial membrane: Pitfalls in the diagnosis of cor triatriatum and supravalve mitral ring

Cor triatriatum and supravalve mitral ring are forms of congenital left ventricular inflow obstruction produced by membranes within the left atrium. Typically, these defects occur as isolated anomalies with manifestations of pulmonary venous obstruction. Four children are presented whose left atrial membrane was associated with other significant cardiac defects, including, in one patient each, simple coarctation of the aorta, sinus venosus atrial septal defect, tricuspid atresia and complex coarctation of the aorta syndrome. The patient with the latter defect had undergone previous pulmonary arterial banding. None of these patients demonstrated significant pulmonary venous obstruction at cardiac catheterization. All patients had a normal value for either pulmonary arterial diastolic or pulmonary arterial wedge pressure. Three mechanisms explained the lack of pulmonary venous obstruction: (1) a large cross-sectional area of membrane openings, (2) an atrial septal defect that was confined to the pulmonary venous chamber and decompressed it by allowing blood to escape into the right atrium, and (3) decreased pulmonary blood flow. The diagnosis was facilitated by two dimensional echocardiography. Accurate diagnosis of left atrial membrane in the setting of other cardiac defects is of practical significance because pulmonary venous obstruction may occur after surgery for the associated defects.

Persistence of fetal circulation syndrome: an echocardiographic study.

Serial echocardiograms were performed on 17 infants with persistence of fetal circulation syndrome to measure right ventricular systolic time intervals from pulmonic valve echograms and left ventricular systolic time intervals from aortic valve echograms. Right ventricular pre-ejection period/right ventricular ejection time ratio was prolonged in PFCS when compared to that in normal newborn infants, and diminished with clinical improvement. Left ventricular pre-ejection period/left ventricular ejection time ratio was prolonged in infants with PFCS. Echographic RPEP/RVET was consistent with the elevated pulmonary artery pressure and pulmonary vascular resistance of PFCS; elevated LPEP/LVET suggested left ventricular dysfunction.

The isovolumic contraction time of the left ventricle. An echographic study.

SUMMARY The echographic isovolumic contraction time (ICT) of the left ventricle (LV) was measured in order to assess alterations of LV performance in children with various forms of cardiac disease. The echographic ICT was defined as the interval between coaptation of the anterior and posterior mitral valve leaflets and aortic cusp opening. Four groups of patients were evaluated: normal (48); LV myocardial disease (20); patent ductus arteriosus (PDA) (19); and aortic stenosis (AS) (15). In normal children ICT shortened with decreasing age and increasing heart rate. Isovolumic contraction time was more influenced by heart rate (HR) than age, but the relationship was still weak (r = 0.61). In patients with LV myocardial disease ICT was markedly prolonged, while in children with patent ductus arteriosus and aortic stenosis it was shortened as compared with normal children (P < 0.01).

Early echocardiographic and pulmonary function findings in idiopathic scoliosis.

Thirty-six children and adolescents with early stages of idiopathic scoliosis underwent evaluation by echocardiography and pulmonary function testing. Mildly increased pulmonary vascular resistance was inferred from an elevated ratio of right preejection period to right ventricular ejection time, an increased right ventricular dimension, and a decreased left ventricular dimension. Since neither decreased arterial oxygen saturation nor increased end-tidal expired carbon dioxide partial pressure was seen, desaturation and hypoventilation should not account for these abnormalities. Pulmonary function parameters showed no distinct patterns of abnormality. Even though the patients were divided into two groups by severity of spinal curvature, the cardiopulmonary measures did not correlate with thoracic deformity. Billowing of the mitral leaflets, termed mitral valve prolapse, was demonstrated in 25% of the subjects. Our findings suggest that cardiopulmonary and thoracic changes in idiopathic scoliosis may develop in parallel and may be expressions of a common collagen defect. However, study of sleep and exercise arterial saturation may be required to rule out intermittent hypoxemia as a precipitating factor of cor pulmonale in scoliosis.

Intracardiac pressure-sound correlates of echographic aortic valve closure.

Echographic aortic valve closure was compared to the dicrotic notch of the aortic pressure and intracardiac A2 to define the exact temporal relationship of the echographic, pressure, and sound parameters of aortic valve closure. Sixteen children, ages 3-20 years, were evaluated by simultaneous aortic valve echograms, micro-manometric aortic root pressure tracings, and intracardiac phonocardiograms recorded at paper speeds of 200 mm/sec. Our observations demonstrated that echographic coaptation of the aortic valve leaflets coincides with the trough of the aortic pressure incisura and the onset of A2. The data suggest that A2 is a result of valve closure.

Echocardiographic estimation of ventricular hypoplasia in complete atrioventricular canal.

Echocardiograms from 10 patients with complete atrioventricular canal (CAVC) were compared with autopsy specimens to determine the capabilities of echocardiography in identifying patients with ventricular hypoplasia. On the basis of echographic ventricular size, patients could be divided into three groups: 1) “balanced” CAVC patients had both increased right left ventricular end-diastolic dimensions (RVED LVED) an increased RVED/LVED ratio; 2) “dominant left ventricular” CAVC patients had an increased LVED small or normal RVED a diminished RVED/LVED ratio; 3) “dominant right ventricular” CAVC patients had an increased RVED, but small LVED, increased RVED/LVED. There was complete agreement between echographic ventricular dominance pathologic findings. This study demonstrates that echocardiography may be valuable in assessing ventricular dominance in the presence of CAVS.