Prenatal diagnosis and outcome of congenital complete heart block: the role of fetal echocardiography.

Between January 1, 1980, and March 1, 1986, congenital complete heart block (CCHB) was diagnosed in 11 fetuses utilizing 2-dimensional and M-mode fetal echocardiography. Four of the eleven cases (36.4%) had otherwise structurally normal hearts; 3 survived the perinatal and neonatal period and 1 patient died at 22 days of age. All mothers in this group had systemic lupus erythematosus. Seven of the eleven fetuses (63.6%) presented with CCHB and associated cardiac malformations. All patients in this group died either in utero or shortly after birth. The discovery of CCHB with associated structural malformations of the heart carries an ominous prognosis for fetal and neonatal survival. The diagnosis of CCHB without associated cardiac malformations carries a more favorable outlook. Accurate prenatal diagnosis of CCHB and underlying cardiac status facilitates parental counseling and patient management planning.

Primary cardiac tumors in children.

Case histories of five children with primary cardiac tumors are presented. The clinical and pathological features of the most frequent cardiac neoplasms in childhood are also reviewed. Cardiac tumors should be suspected in any child with unexplained heart murmurs, congestive heart failure, or cardiac arrhythmias. Echocardiography, cardiac catheterization, and biplane cineangiograms provide diagnostic confirmation. Prompt surgical resection is indicated in all symptomatic patients and in those with significant inflow and outflow tumor-related obstruction. Complete resection is not possible in many patients with cardiac rhabdomyoma or lipoma but removal of the obstructive portion of the tumor frequently provides long-term symptomatic relief.

Comparison of the cardiocirculatory effects of exercise and isoproterenol in children with pulmonary or aortic valve stenosis.

Isoproterenol infusion during cardiac catheterization as a simulator of exercise was evaluated with hemodynamic studies in children with pulmonary (15) or aortic (8) valve stenosis. Cardiac function was monitored during rest, mild exercise and isoproterenol infusion. Similar heart rates were maintained in both procedures. Peak pulmonary and aortic valve gradients as well as right and left ventricular dp/dt/p were significantly higher and cardiac index significantly lower with isoproterenol as compared to exercise. Isoproterenol induced a significantly greater decrease in systemic vascular resistance, and systemic blood pressure than did exercise. Left ventricular systolic pressure rose to similar levels and this resulted in substantially higher peak aortic gradients with isoproterenol. A consistent correlation was observed for peak valvular gradients measured during exercise and isoproterenol in both groups of patients. Accordingly, regression equations were obtained allowing reasonably accurate prediction of exercise valvular gradients on the basis of the isoproterenol data.

Increased cardiac output by downstream pumping with a reversed unidirectional intra-aortic balloon.

Downstream and upstream pumping with unidirectional intra-aortic balloons was compared in 8 open-chest normal mongrel dogs anesthetized with pentobarbital. Downstream pumping effect a 32 per cent increase in cardiac index, a 24 per cent decrease in systemic resistance, and a 2 per cent decrease in heart rate. Upstream pumping did not significantly affect these parameters. Mean aorta pressure proximal and distal to the balloon was not altered significantly by pumping in either direction. This unique observation of increased cardiac output may have important implications for the treatment of low output cardiac failure. Preliminary studies including baroreceptor denervation suggest that a reflex mechanism may be involved.

Hemodynamic effects of rapid atrial stimulation in adult and young dogs.

We evaluated the use of rapid atrial stimulation (RAS) to produce 2:1 atrioventricular (AV) block as a method for treating supraventricular tachycardias. We studied the cardiovascular hemodynamic changes before and after block in eight adult dogs and nine young dogs (3-4 1/2 weeks old). In each dog an electrocardiogram; cardiac index; aortic, pulmonary, and left ventricular (LV) systolic and end-diastolic pressures; and LV (dp/dt) p were recorded simultaneously and pulmonary ans systemic resistances were calculated. Measurements were obtained during (1) the control state, (2) RAS with maximal 1:1 AV conduction, (3) RAS with 2:1 AV block, and (4) RAS with 1:1 AV conduction at 50% of the rate which resulted in 2:1 AV block. Comparison of the hemodynamic effect of RAS with maximal 1:1 AV conduction and hemodynamics in the control state showed that there was a significant decrease in cardiac index and aortic mean pressure of 39% and 15%, respectively. When hemodynamic changes during RAS with 2:1 AV block were compared with those during RAS with maximal 1:1 AV conduction, cardiac index, LV systolic pressure, and aortic mean pressure increased by 52%, 17%, and 22%, respectively. LV (dp/dt) p increased by 20% and was significantly higher during RAS with 2:1 AV block than at higher ventricular rates obtained with RAS and maximal 1:1 AV conduction. We found that in this acute study the hemodynamic findings for the young dogs were similar to those for adult dogs. The data suggest that (1) significant hemodynamic improvement is obtained by RAS causing 2:1 AV block when compared to higher ventricular rates associated with 1:1 AV conduction; (2) in addition to increasing the diastolic filling period, reducing the very high ventricular rates improves the cardiac contractile state, and (3) RAS and 2:1 AV block may provide a useful technique for the management of some patients with intractable supraventricular tachycardia.

Hemodynamic alterations with a reversed unidirectional intra-aortic balloon.

The hemodynamic effects of dual-chambered unidirectional balloon pumping in alternate directions were studied in 44 trials conducted on 8 dogs. Results indicate an increase in cardiac output in normal dogs with downstream pumping by unidirectional intra-aortic balloon, which may have important implications for the treatment of low output cardiac failure.

Cardiac output in infants and children after open-heart surgery.

Green dye measurements of cardiac index (in liters per minute per square meter) were compared in 32 infants and 58 children, 6 and 24 hours after normothermic cardiopulmonary bypass. Cardiac index was significantly lower in infants under one year of age, as compared to older infants and children. This parameter was also lower in patients with total anomalous pulmonary venous drainage, truncus arteriosus, and tetralogy of Fallot. Five infants who died had 6-hour cardiac index determinations of 2.0 L./min./sq. M. Only 2 of 27 survivors had cardiac indices below this level. Simultaneously recorded heart rate and central venous pressure did not correlate with cardiac index. Systolic blood pressure was significantly lower in infants in whom the cardiac index was less then 2.0 L./min./sq. M. (p less than 0.01). However, in individual situations, determination of systemic blood pressure lacked specificity in predicting outcome. Measurements of cardiac index are helpful in the management of infants and children following intracardiac repair by (1) assessing the hemodynamic status, (2) providing a useful indication of the cardiocirculatory effects of therapeutic interventions, and (3) predicting outcome.

Comparative cardiovascular effects of propranolol and practolol in puppies.

The present results indicate that in 3-4-weeks-old puppies propranolol induces a significant depression of cardiovascular function expressed by a decrease in heart rate, myocardial contractility, and cardiac output, and an increase in systemic vascular resistance, in doses beyond beta-blocking levels. In contrast, practolol, in the same dose range, did not induce further cardio-circulatory depression, as shown by levels of heart rate, myocardial contractility, and cardiac output similar to the values obtained with beta-blocking doses of this agent. The cardio-depressant activity observed in puppies with doses of propranolol beyond blocking levels is thought to be due to direct negative inotropic and chronotropic effects of this agent, not related to influences on beta receptor sites. Such effect not observed with practolol at doses well beyond beta-blocking levels suggests that this drug exerts a more selective influence on cardiac sympathetic beta receptors.