Iain F. S. Black

Left ventricular wall stress in compensated aortic stenosis in children

It is known that children with aortic stenosis (AS) frequently have supernormal indexes of left ventricular (LV) pump function and remain compensated for many years. Factors causing this increase in pump performance have not been elucidated. A study was done on LV mechanics in 11 children with AS (aortic valve area 0.5 +/- 0.3 cm2/m2) and 10 normal subjects. The ejection fraction in the AS group (0.88 +/- 0.08) was significantly higher than in normal subjects (0.64 +/- 0.08, p less than 0.001). The mean velocity of fiber shortening was also higher in AS patients (1.80 +/- 0.35 circ/s) than in normal subjects (1.22 +/- 0.21 circ/s, p less than 0.001). The end-systolic volume index in patients with AS (9 +/- 8 ml/m2) was much lower than in normal subjects (27 +/- 8 ml/m2). LV mass in patients with AS was 180 +/- 58 g/m2 compared with 96 +/- 9 in normal subjects. LV wall stress was reduced throughout the cardiac cycle in patients with AS. Peak stress in patients with AS was 238 +/- 51 dynes/cm2 X 10(3) versus 439 +/- 85 in normal subjects. The end-systolic stress-end-systolic volume index ratio, an indicator of contractile state, was not elevated in patients with AS. It is suggested that diminished wall stress in concert with normal contractile function permits the supernormal pump function seen at rest in children with AS.

Successful percutaneous balloon valvuloplasty of the aortic valve in an infant

SummaryPercutaneous balloon aortic valvuloplasty was attempted in an eight-month-old infant with severe aortic valve stenosis. The procedure resulted in a fall in the resting transvalvular systolic pressure gradient from 106 mmHg to 40 mmHg and no aortic regurgitation. Clinical and Doppler echocardiography findings suggest persistent improved status 3 1/2 months after the procedure.

Application of Doppler ultrasound to blood pressure measurement in small infants

An automatic instrument which can transmit and detect ultrasound waves has been used to measure blood pressure in 28 infants weighing from 4.5 to 11 pounds. Results were in close agreement with values simultaneously obtained by direct intra-aortic measurement. In the majority of patients, the mean systolic pressure obtained by the ultrasonic technique was 2.48 mm. Hg below the aortic value; mean diastolic pressure was recorded at 3.32 mm. Hg higher. A range of accuracy for a 4×9 cm. cuff has been determined.

Safety and efficacy of short- and long-term verapamil therapy in children with tachycardia.

Abstract Six children aged 3 months to 11 years were treated with verapamil because of resistant symptomatic supraventricular tachycardia or complications of conventional therapy. Two of the three patients with congenital heart disease were in the postoperative state. The other three had no gross cardiac anomalies. Two patients had supraventricular tachycardia with Wolff-Parkinson-White syndrome, three had ectopic supraventricular tachycardia and one had atrial flutter. Intravenous verapamil was given in a dose of 0.15 to 0.25 mg/kg body weight to four patients, three of whom had successful conversion to sinus rhythm. One patient was given oral verapamil only. Treatment failed in the patient with atrial flutter. Five patients were maintained on oral verapamil therapy. Of these, one patient died of postoperative complications while receiving verapamil, and the remaining four have continued oral verapamil therapy for 1 to 3 1 2 years . The dose is 80 mg every 6 or 8 hours depending on response. Two of the latter four patients have ectopic supraventricular tachycardia that recurs when therapy is stopped. Of the two patients with Wolff-Parkinson-White syndrome, one has had no recurrence of supraventricular tachycardia and the other has had a decrease in both the duration of attacks and their number (from one to two per week to one to two per month). There have been no adverse effects with long-term drug administration. None of the five patients who received intravenous verapamil showed any untoward effects during its administration. This experience indicates that verapamil, which has not been used extensively in children, is an effective and safe antiarrhythmic drug capable of controlling both ectopic and reentrant supraventricular tachycardia when conventional methods fail. The presence of underlying congenital heart disease should not be a contraindication to its use.

Variant angina in an 11 year old boy

Variant angina is a syndrome in which ischemic cardiac pain occurs with ST segment elevation. The syndrome is due at least in part to coronary vasospasm. Although well documented in adults, there are no known reports of this syndrome in children. The clinical, electrocardiographic and echocardiographic findings in an 11 year old boy with variant angina are reported.

Echocardiographic detection of aneurysms of the interventricular septum associated with ventricular septal defect: A method of noninvasive diagnosis and follow-up

Spontaneous closure of a ventricular septal defect is frequently accompanied by the formation of an aneurysm of the membranous septum. The exact anatomic basis for such an aneurysm varies. Some arise from redundant tissue from the endocardial cushions or from adherence of the tricuspid septal leaflet to the defect; the origin of others cannot be determined. Echocardiographic studies in 17 patients with the diagnosis of ventricular septal defect revealed in 7 an aneurysm of the membranous septum that was later confirmed by angiography. In no patient was an aneurysm missed or erroneously diagnosed in the echocardiographic study. Echocardiography can be a useful diagnostic and prognostic tool in the long-term management of patients with ventricular septal defect.

Left ventricular wall stress and function in childhood coarctation of the aorta

Unlike most adults with compensated pressure overload of the left ventricle, children with moderate to severe aortic stenosis exhibit pronounced left ventricular muscle hypertrophy, enhanced ejection performance and diminished wall stress. To determine whether these findings are present in other forms of left ventricular pressure overload in children, left ventricular mechanics were studied by catheterization in 14 children with coarctation of the aorta (average peak gradient 39 +/- 17 mm Hg) and in 10 normal children. Ejection fraction and mean velocity of circumferential fiber shortening in the coarctation group (0.74 +/- 0.09 and 1.71 +/- 0.43 circumferences/s, respectively) were significantly higher than in normal subjects (0.65 +/- 0.05 and 1.27 +/- 0.26 circumferences/s, respectively) (p = 0.008), but the ranges for both groups overlapped. End-systolic stress in children with coarctation (77 +/- 20 dynes X 10(3)/cm2) was less than in normal children (121 +/- 24 dynes X 10(3)/cm2) (p less than 0.001), again with overlap of the ranges for both groups. The ratio of end-systolic stress to end-systolic volume index, an estimate of contractile function, was similar in both groups. Relations between severity of obstruction (left ventricular peak systolic pressure, coarctation gradient) and end-systolic stress and between stress and ejection performance were present within the coarctation group. Comparison of these data with those found in children with moderate to severe aortic stenosis shows a similar but less pronounced response to pressure overload due to coarctation of the aorta.

Improved prediction of peak left ventricular pressure by echocardiography in children with aortic stenosis

Prediction of peak left ventricular pressure by echocardiography in children with aortic stenosis assumes that wall stress is normal. The recent finding that stress is subnormal in many children with aortic stenosis and elevated ejection performance requires reevaluation of this noninvasive technique. By using M-mode echocardiography, left ventricular end-diastolic dimension and wall thickness and left ventricular shortening fraction were measured in 27 children with aortic stenosis undergoing left ventricular pressure measurement by cardiac catheterization. Similar echocardiographic measurements and systolic blood pressure determinations by the cuff method were obtained from 29 normal children. Peak circumferential wall stress and shortening fraction were calculated from the echocardiographic and pressure data. It was found that stress was inversely proportional to shortening fraction for all patients with aortic stenosis (p less than 0.001, r = -0.86). In a subgroup of patients with a shortening fraction of less than 0.40, stress was 262 +/- 20 mm Hg, similar to 280 +/- 30 mm Hg in the normal group but greater than 205 +/- 27 mm Hg in patients with a shortening fraction of 0.40 or greater (p less than 0.001). In patients with aortic stenosis, the ratio of left ventricular end-diastolic wall thickness to cavity dimension predicted peak left ventricular pressure moderately well (r = 0.83, standard error of the estimate [SEE] = 23). The stress-shortening fraction relation was used to estimate stress and correct this ratio in patients with diminished stress and a shortening fraction greater than or equal to 0.40. This yielded a significantly improved correlation (r = 0.93, SEE = 15, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Balloon Angioplasty of Pulmonary Artery Stenoses after Tetralogy of Fallot Repair

Pulmonary artery stenosis complicates the management of patients with tetralogy of Fallot, may be impossible to correct surgically, and affects the longterm outcome.

Electrophysiologic Study in Children: Safety vs. Complications

Electrophysiologic study is a new invasive diagnostic and treatment modality in the pediatric age group. The safety and complication of this procedure is unknown. We would like to review our experience in 101 consecutive children who underwent electrophysiologic study from July 1981 to December 1983.