Martin H. Lees

Problems in the hemodynamic diagnosis of tricuspid insufficiency

Abstract The dependability of RVA in the evaluation of TI was studied in 141 patients with congenital or rheumatic disease. In patients over age 10, angiocardiography revealed TI in 13 and was negative in 27. Eight with positive RVA had cardiac operation and TI was confirmed in seven; three not having been operated upon were probably false positives. Six with negative RVA had an operation and no TI was detected. In 20 per cent of 95 younger patients, RVA revealed TI, often believed catheter induced. RA pressure criteria commonly employed in the hemodynamic diagnosis of TI were tested. RA pressure level and contour were analyzed in 27 cases proved negative for TI by RVA and in seven proved positive by operation. An X descent shallower than Y correlated better with atrial fibrillation than with TI; X deeper than Y correlated better with sinus rhythm than with tricuspid competence. RVA can exclude TI but yields false positive studies. RA pressure contour is believed not to have the usually accepted significance.

Maternal placental and myometrial blood flow of the rhesus monkey during uterine contractions

Abstract Cardiac output and regional blood flows were measured in 20 nonpregnant and 10 pregnant rhesus monkeys at term. Pregnant animals at term had 27 per cent higher cardiac output and a sixteenfold increase in the fraction of cardiac output directed to the uterus. Uterine contractions were induced by amniotic fluid removal. Cardiac output was consistently higher during contractions than during relaxation. Maternal placental flow before labor was 4.5 per cent of cardiac output, decreasing to 2.9 per cent during uterine contractions and increasing to 7.2 per cent during uterine relaxation. The fraction of cardiac output reaching the placenta was most reduced with higher intra-amniotic pressures. Myometrial flow rose from a control 0.48 per cent of cardiac output before labor to 0.64 per cent during contractions and to 0.95 per cent during uterine relaxation.

Ventilatory response to carbon dioxide of infants following chronic prenatal methadone exposure

Nine infants chronically exposed to methadone in utero were studied from birth to 7 weeks of age (66 studies). The maternal dose of methadone/HCl during the third trimester ranged from 14 to 70 mg orally once a day. The mean (range) of serum methadone t 1/2 in the neonates was 53 hours (22 to 113). In the first four days of life the methadone-exposed infants had a significantly (P less than 0.005) decreased sensitivity to carbon dioxide compared to control infants as measured by the slope of the ventilatory response curve. The mean slope +/- SD for the methadone-exposed infants, 10.4 +/- 7.7 ml/minute/kg mm Hg, was one third that of the control group (30.0 +/- 9.9 ml/minute/kg/mm Hg). Total ventilation, respiratory frequency, oxygen consumption, and end-tidal PCO2 were not significantly different in the two groups. The depressed ventilatory response to carbon dioxide persisted for an average of 15 days and lasted as long as 31 days in one infant. The time required to achieve a normal slope was not related to the size of the maternal methadone dose, to neonatal serum methadone t 1/2, or to the severity of and therapy for methadone withdrawal. If this abnormality in sensitivity to carbon dioxide persists beyond the neonatal period in some infants, it may contribute to the increased incidence of the sudden infant death syndrome among infants exposed to methadone in utero. Measurement of the ventilatory response to carbon dioxide may be clinically useful to determine which of these infants are at risk for SIDS.

Uterine contractility and regional blood flow responses to oxytocin and prostaglandin E2 in pregnant rhesus monkeys

The effects of oxytocin and prostaglandin E 2 (PGE 2 ) infusions on regional blood flow (measured by radioactive microspheres) and myometrial contractility were studied in 18 pregnant rhesus monkeys near term. We observed no significant differences between PGE 2 and oxytocin in cardiac output, hemodynamics, or uterine activity. Their effects on the regional distribution of systemic blood flow were similar although the gastrointestinal tract received an increased percentage of cardiac output after PGE 2 . A relative placental ischemia, together with a myometrial hyperemia, was observed during labor. Uterine contraction produced a large reduction (average 73 per cent) in placental blood flow whereas myometrial blood flow was maintained or sometimes increased. A significant negative correlation was observed between intra-amniotic pressure and placental blood flow. During uterine relaxation, placental flow partially recovered whereas myometrial flow nearly doubled the prelabor values. We conclude that (1) in the dose ranges studied, oxytocin and PGE 2 produce similar effects on myometrial contractility and uteroplacental blood flow, and (2) the vascular beds of the placenta and myometrium respond differently to labor of moderate intensity.

Serial cardiac catheterizations and exercise hemodynamics after correction of tetralogy of Fallot: average follow-up 13 months and 7 years after operation.

Eleven patients had right heart catheterization an average of 13 mo after total correction of tetralogy of Fallot, and the procedures were then repeated an average of 7 years postoperatively. In the intervening time there was generally no important change in the pressure gradient between the right ventricle and pulmonary artery or in right ventricular systolic pressure. Mean right atrial pressure tended to fall with time. Arteriovenous oxygen difference at rest was lower at the second study, and the resting cardiac output was generally normal. One patient with a persistent ventricular septal defect had progressive hemodynamic deterioration between the two studies. Exercise performance up to 10 years postoperatively was also assessed. The relationship between oxygen consumption and cardiac output was usually normal, but exercise magnified the right hearts filling pressure abnormalities. In the absence of an easily demonstrable ventricular septal defect, right heart hemodynamics were either stable or improved up to 10 years postoperatively. The exercise response of cardiac output was usually normal at moderate work loads.

Total correction of tetralogy of Fallot in infancy. Postoperative hemodynamic evaluation.

Total intracardiac repair of symptomatic tetralogy of Fallot was accomplished in twenty-nine infants under two years of age with a mortality of six per cent. All twenty-seven survivors are asymptomatic. Postoperative hemodynamic evaluation of 17 randomly selected children was performed at least 12 months following surgery. Pulmonary regurgitation was present in 12 of the 17 children but was well tolerated, with only minimal cardiac enlargement and in no case were there symptoms or important hemodynamic consequences. Growth of the pulmonary artery with respect to the aorta occurred. Normal left ventricular performance was indicated by normal ejection fraction and normal systemic arterial pressure. Intellectual and social development were indistinguishable from a “normal” group of randomly selected children as assessed by detailed psychological testing.

Catecholamine metabolite excretion of infants with heart failure

Twenty-four hour excretion of the catecholamine metabolites, normetanephrine and metanephrine (NMN+MN) and vanillyl-mandelic acid (VMA), was found to be elevated more than twofold in infants with severe heart failure, probably indicating augmented catecholamine biosynthesis. The role of catecholamines in the pathophysiology of heart failure is discussed. Infants with severe cyanosis rather than heart failure as the major problem showed a minor increase of NMN+MN excretion but not of VMA excretion.

Postoperative hemodynamic and electrophysiologic evaluation of the interatrial baffle procedure

Hemodynamic and electrophysiologic studies were performed in 11 children with dextrotransposition of the great arteries an average of 26 months after the interatrial baffle procedure and, in 2 patients, additional closure of a ventricular septal defect. All children are clinically well. Right to left shunts ranging from 28 to 63 percent of systemic blood flow were found at the superior vena caval-baffle junction in four children. The superior vena caval-baffle gradient averaged 7 mm Hg (range 0 to 22). Right ventricular stroke work index averaged 39 g-m/beat per m2 and right ventricular end-diastolic pressure 9 mm Hg. These values were not significantly different from the values for the systemic left ventricle in a comparable group of normal children (average left ventricular stroke work index 45 g-m/beat per m2 and average left ventricular end-diastolic pressure 8 mm Hg). Cardiac index, heart rate and arteriovenous oxygen difference were also normal. No child has complete heart block. His bundle recording demonstrated normal H-V intervals (range 27 to 40 msec); 4 of the 11 had a prolonged A-H interval. Left ventricular systolic pressure was less than 40 mm Hg in all but two children who had significant subpulmonary stenosis. Pulmonary vascular resistance averaged 1.9 units and was decreased in all children. We conclude that up to 37 months postoperatively, despite some residual abnormalities, the clinical and hemodynamic condition of these children is excellent.

Heart failure in the newborn infant

Summary Heart failure in the newborn infant is characterized by tachypnea, tachycardia, feeding difficulties, pulmonary râles and rhonchi, hepatic enlargement, and cardiomegaly. Less common signs include visibly elevated systemic venous pressure, peripheral edema, ascites, pulsus alternans, gallop rhythm, and inappropriate sweating. When heart failure occurs in the first days and weeks of life it is usually due to structural congenital heart disease or to primary myocardial disease. It may on occasion, however, be secondary to arrhythmia, respiratory disease, central nervous system disease, anemia, systemic or pulmonary hypertension, or septicemia. The distinction between left heart failure and right heart failure is less obvious in the newborn infant than in the older child or adult. The newborn infant with advanced near-terminal heart failure is often pallid and apathetic. He has minimal spontaneous movements, diminished peripheral pulses, bradycardia, apneic periods, splenic enlargement, widespread peripheral edema, and gross cardiomegaly. Near-terminal heart failure may closely simulate septicemia, meningitis, bronchiolitis, or severe pneumonia. Certain noncardiac conditions may also simulate heart failure. Such conditions include hypoglycemia, many forms of respiratory disease, renal disease, the rubella syndrome, liver enlargement due to a variety of diseases, factitious cardiomegaly, cardiomegaly not due to heart failure, peripheral edema due to hypoalbuminemic states or lymphedema, and ascites due to escape of chyle or liver disease. The management of heart failure in the newborn infant requires a rapid assessment of the effect of the medical measures described. Deterioration or failure to improve within 12 hours is usually an indication for cardiac catheterization and angiocardiography. In general, the younger the infant the more urgent are diagnostic studies and surgery, if indicated. The use of an incubator is essential for optimal care. A number of emergency measures are available for the critically sick newborn infant with heart failure. The usual objective of these more drastic measures is to produce a temporary improvement so that other measures which may provide longer range benefit may be utilized.

Bronchial Circulation in Severe Multiple Peripheral Pulmonary Artery Stenosis Case Report Illustrating the Origin of Continuous Murmur

In an infant with severe, multiple, peripheral pulmonary artery stenoses angiography clearly demonstrated enlarged tortuous bronchial arteries, especially in the right lung, where a major tortuosity corresponded closely to the point of maximal intensity of a loud continuous murmur. Increased bronchial circulation may be responsible for continuous murmurs in patients with severe multiple peripheral pulmonary artery stenosis.