Gregory L. Johnson

Ventriculocoronary connections in hypoplastic left hearts: an autopsy microscopic study.

Serial microscopic sections of the left ventricular myocardium were examined in 12 autopsy specimens of hypoplastic left heart syndrome. Multiple ventriculocoronary arterial connections, thickwalled coronary arteries, prominent endocardial fibroelastosis, myofiber disarray and focal calcification/ scarring of the myocardium were noted in the cases with patent left ventricular inflow and obstructed outflow. The persistent embryonic microvascular pattern noted in these cases may be related to intrauterine outflow obstruction and could limit surgical attempts to produce a functional left ventricle in infants with hypoplastic left heart syndrome.

Pulmonary atresia with intact ventricular septum and ventriculocoronary communications: surgical significance.

The first stage of a repair of pulmonary atresia with intact ventricular septum (type I) was attempted in a 2-day-old infant. At surgery, decompression of the hypertensive small right ventricle was followed by a sudden loss of myocardial contractility and death. Postmortem examination revealed a fistula with a large orifice in the right ventricular infundibulum that communicated directly with the left main coronary artery. Severe hypertensive changes indicative of abnormally high perfusion pressure were noted in the distal left coronary artery branches. The clinical course suggests that the effect of relieving right ventricular outflow obstruction was a reduction of left main coronary artery blood flow, resulting in fatal intraoperative myocardial ischemia. This unusual case draws attention to the anomalous ventriculocoronary communications often present in pulmonary atresia and their potential for limiting a successful surgical repair.

Accuracy of combined two-dimensional echocardiography and continuous wave Doppler recordings in the estimation of pressure gradient in right ventricular outlet obstruction

Fifteen patients (median age 8.5 years) with fixed right ventricular outflow tract obstruction were evaluated by two-dimensional echocardiographically directed continuous wave Doppler ultrasound within 24 hours of cardiac catheterization. Pulmonary artery blood velocity measurements were determined from a real time spectral display of pulmonary artery flow profile and converted to pressure drop utilizing a modified Bernoulli equation. Use of both parasternal and subcostal imaging permitted more accurate detection of maximal flow velocity than did use of either approach alone. Gradients estimated from Doppler recordings correlated well with those measured at cardiac catheterization (correlation coefficient = 0.95, standard error of the estimate = 7.9 mm Hg) with a trend to slight underestimation of gradient in more severe obstruction. In three patients with combined valvular and subvalvular stenosis and one patient with right ventricular outlet obstruction due totally to a ventricular septal aneurysm, Doppler estimation of gradient provided an accurate assessment of total right ventricular-pulmonary artery gradient. Thus, continuous wave Doppler ultrasound combined with two-dimensional echocardiography provides a reliable noninvasive method of estimating pressure gradient in patients with right ventricular outflow tract obstruction.

Late Echocardiographic Findings Following Childhood Chemotherapy with Normal Serial Cardiac Monitoring

Purpose Late development of myocardial dysfunction years following successful treatment of childhood malignancy with anthracyclines is well documented. There have been few studies of late cardiac performance in children in whom serial monitoring during treatment suggested normal cardiac performance, and those studies that do exist rely on the results of extensive evaluation. It was our purpose to determine whether findings consistent with known late cardiac changes could be discovered in these patients by echocardiographic monitoring similar to that routinely performed during treatment. Patients and Methods A total 28 consecutive asymptomatic patients who had completed anthracycline therapy at least 3 years previously, had been free of malignant disease since the completion of therapy, and who had had normal serial echocardiographic studies during and at completion of treatment were restudied by echocardiography. Of these 28, 12 had undergone mediastinal radiation as part of their acute treatment. Results Four patients (14%) of the study group were found to have abnormally low values for left ventricular shortening and ejection fractions. All four had also received mediastinal radiation. The remaining 24 patients, while having values for shortening fraction within the normal range, had, as a group, experienced a significant decrease in echocardiographic left ventricular shortening since completion of treatment. In these patients, left ventricular wall thickness had not increased commensurate with growth in body size and left ventricular cavity dimension. Conclusions The known incidence of late asymptomatic cardiac dysfunction is confirmed despite the presence of persistently normal echocardiographic monitoring studies during and at completion of anthracycline treatment. Additionally, as a population, these patients show impaired myocardial growth over time, placing them at risk for future myocardial failure. Normal echocardiographic monitoring studies during antineoplastic treatment in children may not necessarily predict that patients will be free of the development of late cardiac dysfunction. Routine serial echocardiographic monitoring can, however, be helpful in the long-term management of these patients.

Cardiorespiratory effects of premedication for children.

Cardiovascular and respiratory effects of pediatric preanesthetic premedication have received only minimal attention, probably because most children tolerate such drugs without apparent ill effect.In children with congenital heart disease or other serious illness, there is often reluctance to use premedication. We sought to determine whether different premedication regimens produced significant cardiorespiratory effect. A randomized prospective study of the cardiovascular and respiratory effects of different oral, nasal, and rectal premedication regimens was conducted. Fifty-eight young children (average age 2.7 yr) were studied. Oral meperidine (3 mg/kg) with pentobarbital (4 mg/kg) decreased heart rate, mean arterial pressure, cardiac index, respiratory rate, and oxygen saturation. Stroke volume was maintained. Nasal ketamine (5 mg/kg) with midazolam (0.2 mg/kg) produced no significant cardiovascular or respiratory effects. Rectal methohexital (30 mg/kg) increased heart rate with a coincident decrease in stroke volume but had no other positive or negative cardiac or respiratory effect. This information documents disparate cardiorespiratory effects of different preanesthetic medications in normal children. (Anesth Analg 1995;80:506-10)

The occurrence of hyperaldosteronism in infants with congestive heart failure

Serum aldosterone and plasma renin were measured in 20 normal infants and 15 infants with congestive cardiac failure. Serum aldosterone was significantly increased (151 +/- 38 ng/dl mean +/- standard error of the mean) in patients before treatment when compared with aldosterone in normal infants (29 +/- 7 ng/dl). Increasing serum aldosterone was related to increasing plasma renin. The response to furosemide appeared to be inversely related to serum aldosterone concentrations. In four infants, administration of an aldosterone antagonist (spironolactone) resulted in improved diuresis and decreased serum aldosterone. Hyperaldosteronism is an important factor contributing to fluid and sodium retention in infants with heart failure.

Echocardiography in hypoxemic neonatal pulmonary disease

Sixteen newborn infants with severe pulmonary parenchymal disease and profound hypoxemia were treated with mechanical ventilation, alkalinization, and intravenous tolazoline. Eight infants responded within two hours of initiation of tolazoline therapy with a rise in Pao2 by at least 100% of pretreatment values (mean = 188%, range = 103 to 427%). Eight infants showed little or no change in Pao2 with administration of tolazoline. Echocardiographic evaluation prior to therapy demonstrated marked elevation in both left (LPEP/LVET = 0.52 +/- 0.13) and right (RPEP/RVET = 0.56 +/- 0.08) ventricular systolic time intervals in the eight infants who subsequently responded to tolazoline. Systolic time intervals in nonresponders were within the normal range (LPEP/LVET = 0.37 +/- 0.03, RPEP/RVET = 0.33 +/- 0.04) and were not significantly different from those observed in a control group of 15 infants with pulmonary disease requiring mechanical ventilation but without hypoxemia. Following tolazoline therapy, systolic time intervals in all eight responders fell to normal values. Echocardiography can provide a safe, noninvasive method for identifying those infants with primary pulmonary disease and severe hypoxemia who could be expected to benefit from tolazoline therapy, thereby avoiding tolazoline side effects in infants for whom tolazoline therapy can be predicted to be of little benefit.

Echocardiographic evaluation of fixed left ventricular outlet obstruction in children. Pre and postoperative outlet obstruction in children.

Rencently, several investigators have utilized the echographically determined magnitude of relative left ventricular posterior wall hypertrophy as a reflection of normalized systolic wall stress to estimate left ventricular systolic pressure noninvasively. In this study, relative wall thickness determined echographically was compared to peak systolic pressure measured at catheterization in 20 children without obstruction to left ventricular outflow and with normal left ventricular function. From these data a relationship, pressure = 225 X left ventricular systolic wall thickness/left ventricular end-systolic internal dimension, was derived. The relationship was then applied to 57 children with fixed aortic stenosis. Left ventricular pressure estimated echographically compared well with that demonstrated at cardiac catheterization (r = 0.89). Twenty-one patients had further echographic studies following surgical relief of outlet obstruction. Estimated left ventricular pressure fell to normal values within two months following surgery in over half the patients with good surgical relief of obstruction, and was normal at subsequent studies up to 22 months postoperatively in all but one patient with good surgical relief. In patients in whom outlet obstruction was not adequately relieved at surgery, echographically estimated left ventricular pressure remained persistently elevated.

Neonatal supraventricular tachycardia following prolonged maternal ritodrine administration

get-y for gynecologic malignancy have shown that the deposition of “‘In-labeled platelets in the postoperative field is inconsequential in the imaging of a normal venous blood pool in the pelvis. To our knowledge, the present case demonstrates the first diagnosis of an asymptomatic pelvic vein thrombosis and subsequent pulmonary embolus by a noninvasive diagnostic technique, “‘In-labeled platelet imaging. Although further experience is required to delineate the diagnostic sensitivity and specificity of “‘In-labeled platelet imaging, this noninvasive &agnostic technique may allow the early diagnosis of previously occult thrombosis in pelvic veins. Institution of anticoagulant therapy may further reduce the morbidity and mortality of pehic surgery and childbirth.

Echocardiographic systolic time intervals in premature infants with patent ductus arteriosus

SummaryThirty-six premature infants with respiratory distress syndrome and clinically significant patent ductus arteriosus (PDA) were studied by M-mode echocardiography before and after closure of the ductus. Before closure the ratio of left ventricular preejection period to left ventricular ejection time (LPEP/LVET) was .26±.03 (mean±SD). After closure of the ductus, LPEP/LVET was .38±.04 (mean±SD), significantly different from the value before closure but not significantly different from the value found in 21 control infants; also, a ratio < .30 was always associated with a clinically significant shunt. The combination of systolic time interval measurement with standard M-mode measurement of the left side of the heart enhanced echocardiographic detection of PDA in our series. Serial evaluation of systolic time interval measurements may provide a further index of left-to-right shunt through a PDA and be a valuable adjunct to the clinical management of these patients.