Effects of chronic ethanol consumption on the myocardial hypertrophic response to a pressure overload in the rat.
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Biomedical subjects
Publications and source records attributed to V Whitman.
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The newborn infant with a congenital diaphragmatic hernia (CDH) who develops severe respiratory distress requiring operative repair within the first 24 hours of life represents one of the most challenging problems in pediatric surgery. The mortality in these infants still exceeds 50% and has historically been attributed to ventilatory insufficiency secondary to pulmonary hypoplasia. However, the primary abnormality in these neonates seems to be an increase in pulmonary vascular resistance with an elevation of pulmonary artery pressure, right-left ductal shunting, preductal shunting and progressive hypoxemia. Eighteen neonates with a CDH were operated upon within the first 24 hours of life with a mortality of 38%. In no instance did ventilatory insufficiency seem to be a major factor in the death of the patient. Seven infants with progressive hypoxemia were treated with a vasodilator, tolazoline. Six of the seven infants showed an initial response to treatment, with a rise in preductal PaO2 and a decrease in ductal shunting. Four of these seven desperately ill neonates survived. Pathologic examination of the pulmonary vasculature in the non-survivors revealed an increase in muscle mass within the pulmonary arterioles. An exaggerated vasoconstrictive response of an abnormally hypertrophied pulmonary vascular bed leading to an elevation of pulmonary vascular resistance, rather than abnormalities of ventilation, appears to be the important mechanism leading to the often fatal hypoxemia observed in the neonate with a CDH. Improved survival will depend upon the successful management of the deranged pulmonary vascular hemodynamics seen in these infants.
Infants with aortic arch interruption of juxtaductal coarctation of the aorta may depend on patency of the ductus arteriosus to provide adequate lower body perfusion. In many such infants the ductus arteriosus constricts after birth, resulting in severe heart failure, poor systemic perfusion and acidemia. We infused prostaglandin E1 (PGE1) at a rate of 0.05--0.1 microgram/kg/min into seven infants with aortic arch interruption and eight infants with coarctation. In one infant in each group the ductus arteriosus was already closed and did not reopen. In one infant with coarctation an adequate trial was not accomplished, and in another adequate pressure measurements were not obtained. Of the remaining 11, the ductus arteriosus was effectively dilated by PGE1 in 10 infants. This was evidenced by an increase in descending aortic blood pressures and a reduction in the pressure difference between the main pulmonary artery and descending aorta in six infants with aortic arch interruption and between ascending and descending aorta in four infants with coarctation. Lower body perfusion improved and left ventricular failure was improved. The infant who did not respond was 5 months old. There were no complications.
Seven infants weighing from 6.4 to 10.3 kg underwent correction of transposition of the great arteries by the venous transposition operation as described by Shumacker. In this operation, a new atrial septum is constructed using a bipedicled right atrial flap, and the lateral atrial wall is constructed using a viable pericardial flap. Three of the patients had an associated ventricular septal defect. Six of the seven patients survived and have had an excellent clinical result. Although atrial arrhythmias were common in the early postoperative period, all patients are now in sinus rhythm. Two patients have had postoperative cardiac catheterization and cineangiography, which showed excellent hemodynamic results. The modified Shumacker operation preserves two of the three internodal pathways, provides a compliant, viable atrial septum, and permits fabrication of a generous-size physiological left atrium. This appears to offer advantages not present in the Mustard procedure.
Two infants with isolated congenital tricuspid incompetence appeared to have associated right ventricular outflow tract obstruction at diagnostic evaluation, including catheterization and cineangiography. One infant died during surgery; the other improved rapidly and survived with medical therapy. We discuss the problem of establishing the presence of patency of the right ventricular outflow tract in infants with massive tricuspid incompetence and outline an approach to the management of infants whose diagnosis remains unclear even after careful evaluation.
A new left ventricular outflow tract prosthesis is described. It consists of a tightly woven Dacron graft with one end modified by being wrapped around a thin perforated stainless steel tube to form a rigid left ventricular insertion port and the other end anastomosed to a Hancock xenograft valved conduit for suture to the arterial system. The prosthesis is simple in design and flexible enough to permit anastomosis to any portion of the abdominal aorta. In addition, since the entire blood conduit consists of a porous woven arterial graft and a tissue valve, anticoagulants are not required. The prosthesis has been successfully employed in a 7-year-old boy who had undergone two previous open-heart operations for resection of a subaortic ring but who had persistent evidence of severe residual stenosis. We believe this conduit has advantages over present commercially available units.
Recent experience with implanted cardiac pacemakers in nine young patients is reported. Advance in technology include improved pacemaker generator design and placement, and improved lead design and placement. No patients died; our only complication, failure to capture, required repositioning of the lead. All pacemaker replacements were elective. This series helps to define the more favorable current prognosis for the young patient needing pacemaker therapy.
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Digoxin therapy was evaluated retrospectively in a group of 30, and prospectively in a group of 16 low-birth-weight, premature infants with cardiorespiratory symptoms due to persistent patency of the ductus arteriosus. The response to decongestive therapy was equivocal. Digoxin levels in serum varied between 1.5 and 13 ng/ml. Digoxin half-life in serum exceeded three days in four patients. Fourteen of the combined group of 46 infants had signs of toxicity of digoxin. High dosage, inadvertent overadministration, and variable clearance of digoxin, as well as special characteristics of the patients studied, are postulated as explanations for the high incidence of toxicity. This study suggests that digoxin therapy in low-birth-weight, premature infants with patent ductus arteriosus is not without risk.
Pulmonary vascular obstructive disease developed postoperatively in an infant with aortopulmonary transposition and intact ventricular septum who underwent a Mustard operation in 3 months of age. Preoperative catheterization had shown normal pulmonary artery pressures. Four months after surgery, catheterization showed pulmonary artery systolic pressure above the systemic level and a tortuous, attenuated pulmonary vascular tree visualized angiographically. Early corrective surgery may not preclude the development of pulmonary vascular obstructive disease in patients with aortopulmonary transposition.
Persistent stenosis or recoarctation occurs in 16 to 33% of infants who undergo repair of coarctation of the thoracic aorta by use of end-to-end anastomosis. This report describes the results in 12 infants of repair of coarctation of the aorta using a left subclavian artery flap procedure. Cardiac catheterization and cineangiography performed in four patients from 4 to 66 months following repair showed a 10 mm systolic gradient in one patient and no evidence of significant stenosis in any patient. The eight other patients have had recent sphygmomanometer pressures recorded from 1 to 29 months after repair. Four patients had no gradient while three patients had a systolic pressure gradient of 8, 10, and 12 mm Hg. Results suggest a smaller incidence of persistent stenosis or recoarctation following subclavian flap procedure than following end-to-end anastomosis. The subclavian flap operation provides an adequate aortic lumen with good growth potential. It is recommended as the operation of choice for infants with the most common form of coarctation of the aorta.
In a randomized clinical trial designed to evaluate the effect of diuresis on infants with hyaline membrane disease, seven infants were treated with furosemide (2 mg/kg intravenously) and five received 5% dextrose water in 0.225% sodium chloride (control group). Arterial blood gas analyses performed before and during the six hours after treatment showed no significant difference between control and treated infants. Urine output and urine sodium and calcium loss were significantly increased (P less than .05) in the infants receiving furosemide. The diuresis seemed to have no effect on left atrial size determined echocardiographically, whereas measurements of dynamic skinfold thickness suggested mobilization of subcutaneous water. One infant became seriously dehydrated and hypotensive secondary to a massive diuresis. We concluded that furosemide had a potent diuretic effect in infants with hyaline membrane disease but does not improve cardiorespiratory function acutely. This may be because of failure to mobilize pulmonary interstitial fluid in the time period tested. It may also be possible that the presence of pulmonary interstitial fluid does not play an important role in the impairment of gas exchange in the acute stage of hyaline membrane disease.
An infant, who was conjoined to a partially formed twin, died from congenital cardiac disease which could not be diagnosed accurately by catheterization and cineangiography. Pathologic examination showed a triventricular heart with three atrioventricular valves. One great vessel system was present, and the aorta was transposed. The findings in this infant suggest that the incorporation of cardiac anlage from an incompletely or abortively formed fetus may explain the presence of supernumerary structures in complex congenital cardiac malformations.
A patient with complex congenital heart disease associated with a horizontal interventricular septum is described. In addition the ventricles were inverted, both great vessels arose from the left-sided right ventricle in the dextrotransposed position, and he had a ventricular septal defect of the type usually seen in endocardial cushion defect. Correction was performed using a Rastelli type procedure with good hemodynamic results.
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