Flunarizine and alpha-adrenergic responses in isolated canine saphenous veins.

Experiments were designed to determine how flunarizine affects contractions of cutaneous veins to alpha-adrenergic activation. Rings of canine saphenous vein were mounted at optimal length for isometric tension recording in organ chambers filled with physiological salt solution. At concentrations higher than those needed to inhibit KCl-induced contractions, flunarizine inhibited the contractile responses evoked by alpha 2-adrenergic agonists (B-HT 920, xylazine), partial (St-587) and full (cirazoline, phenylephrine) alpha 1-adrenergic agonists and the combined alpha 1-/alpha 2-adrenergic agonist, norepinephrine. The inhibitory effect of flunarizine against alpha 2-adrenergic responses was similar to that produced by other calcium-antagonists and results presumably from inhibition of the influx of extracellular calcium. The inhibitory effect of flunarizine against alpha 1-adrenergic responses was greater than expected and appears to result from competitive antagonism of alpha 1-adrenoceptors (pA2 = 5.79). Therefore, flunarizine can decrease adrenergic contractile responses by depressing the influx of extracellular calcium and by blocking postjunctional alpha 1-adrenoceptors.

Transluminal balloon coarctation angioplasty: experience with 27 patients.

Transluminal balloon angioplasty (BA) was performed in 27 consecutive patients with coarctation of the aorta (COA), including 7 infants with preductal COA, 7 patients with restenosed COA after surgical repair, and 13 older children and 1 adult with unoperated COA. The patients were 4 days to 27 years old. The balloon was positioned across the COA and inflated sequentially to pressures of 100 and 120 psi, each inflation lasting for 5 to 10 seconds. Peak systolic pressure gradient (PSG) across the COA was recorded and an aortogram was performed before and immediately after BA. PSG also was recorded during follow-up studies performed in 13 patients 3 to 24 months after BA. BA was performed without complications in each patient. Immediately after BA, the mean PSG was reduced from 49 +/- 21 to 10 +/- 7 mm Hg (p less than 0.01), and the mean COA diameter increased from 3.9 +/- 1.4 to 9.6 +/- 3.6 mm (p less than 0.01). After a follow-up period of 3 to 24 months, the mean PSG remained low (15 +/- 11 mm Hg) and the mean COA diameter increased to 10.5 +/- 4.6 mm. BA can be performed safely. It can be a useful palliative treatment in seriously ill infants with COA.

Cardiopulmonary reflexes and blood pressure in exercising sinoaortic-denervated dogs.

To examine the role of cardiopulmonary receptors in arterial blood pressure regulation during and after exercise, conscious dogs with chronic sinoaortic denervation were subjected to 12 min of light exercise and 12 min of exercise that increased in severity every 3 min. Hemodynamic measurements were made before and after interruption of cardiopulmonary afferents by bilateral cervical vagotomy. During both exercise protocols, after an initial transient decrease, the arterial blood pressure remained close to resting values before and after vagotomy. On cessation of the graded exercise, the arterial blood pressure did not change before, but a rapid and sustained increase in pressure occurred after vagotomy. At the time of this increase the cardiac output and heart rate were returning rapidly to the resting level. The study demonstrates that in the chronic absence of arterial baroreflexes, vagal afferents prevent a rise in arterial blood pressure after vigorous exercise presumably by the action of cardiopulmonary receptors causing a rapid dilatation of systemic resistance vessels.

Correlation of two-dimensional echocardiographic and autopsy findings in complete transposition of the great arteries.

Autopsy and antemortem two-dimensional echocardiographic findings were compared in 30 cases to assess the predictive accuracy of two-dimensional echocardiography in complete transposition of the great arteries, and thus its potential for replacing or altering an invasive examination. These cases represent consecutive autopsy cases of transposition between January 1978 and December 1982. Ages at echocardiographic study ranged from 1 day to 15.5 years (median 8.5 months). Transposition of the great arteries had been diagnosed correctly in every case, and all associated anomalies identified by two-dimensional echocardiography were confirmed at autopsy. Several additional anomalies not found by two-dimensional echocardiography were apparent at autopsy; however, most were minor and insignificant. The only potentially significant false negative findings were one ventricular septal defect, two small atrial septal defects, one mitral valve anomaly, one tricuspid valve anomaly, three instances of patent ductus arteriosus and four instances of persistent left superior vena cava. Although significant pulmonary stenosis was predicted correctly, the site of stenosis was not accurately defined in four cases. Two-dimensional echocardiography is a reliable means of diagnosing transposition of the great arteries. It can limit the need for angiocardiography in the neonate; and in older infants and children, it should be used to complement cardiac catheterization and angiocardiography. The latter may be indicated, especially before surgical repair, to better define small ventricular septal defects, site of pulmonary stenosis, atrioventricular valve insufficiency and patent ductus arteriosus.

Coronary artery compression with fatal myocardial ischemia. A rare complication of valved extracardiac conduits in children with congenital heart disease.

Three children with congenital heart disease died after surgical procedures involving the placement of valved extracardiac conduits; their deaths were caused by myocardial ischemia following coronary artery compression by the metallic stent of the conduit valve. The first and second patients died of acute myocardial ischemia or infarction during the immediate postoperative period, whereas the third patient died of chronic myocardial ischemia and progressive heart failure several months after the operation. In a fourth patient the problem of possible coronary artery compression was suspected on completion of the surgical procedure, and the valve stent was then repositioned away from the coronary artery; this resulted in marked hemodynamic improvement. Fatal myocardial ischemia from coronary artery compression is a rare but potential complication of valved extracardiac conduit placement in children with congenital heart disease. Preoperative assessment of coronary artery distribution is indicated in those patients with prior intrapericardial operations and subsequent pericardial adhesions. Such assessment in previously unoperated patients may be undertaken at the time of conduit operation. Proper conduit placement and intraoperative recognition of possible coronary artery compression by the conduit are important in preventing significant ischemic complications.

Diagnosis of pericardial cyst in a young child by computed tomography of the thorax.

Computed tomography can be very useful in the assessment of mediastinal masses in children. In this case, it provided for the specific diagnosis of a pericardial cyst in a young child, obviating the need for invasive evaluation or surgery.

Closed transventricular pulmonary valvotomy in infants.

In an effort to reassess the efficacy of closed transventricular valvotomy in infants with severe pulmonary stenosis, we reviewed 24 consecutive patients who underwent closed transventricular valvotomy. The age range was 1 day to 11 months (median 53 days), with 10 patients under 1 month and 21 under 6 months of age. The weight range was 2.6 to 9.4 kg (median 4.1 kg). The long-term results were assessed by comparing the postoperative to the preoperative clinical and hemodynamic data. The 20 survivors were followed up for 3 to 133 months (median 54 months). All were asymptomatic upon the last follow-up visit, and their electrocardiograms and chest x-ray films were normal or improved. In 12 patients who had cardiac catheterization 7 to 85 months (median 50 months) after operation, the range for the right ventricular-to-left ventricular, or systemic arterial, peak systolic pressure ratio (RV:LV) was 0.97 to 1.7 preoperatively (mean 1.31) and 0.22 to 0.94 postoperatively (mean 0.42) (p less than 0.001). In order to assess the significance of the RV size for the surgical survival, we measured the preoperative RV end-diastolic volume (RVEDV) in 17 patients. Twelve patients had a normal or enlarged RV and all survived the operation, whereas two of the five patients with an RVEDV more than 2 SD below the normal mean (RVEDV less than 23 ml/m2) died postoperatively (p = 0.075). We conclude that closed transventricular valvotomy can be done successfully in infants with severe pulmonary stenosis and an RV which is not small. The risk of cardiopulmonary bypass is avoided and good long-term results can be obtained. We also present evidence that a small RV (RVEDV less than 23 ml/m2) is a potentially important predictor of the surgical risk.