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Biomedical subjects

S Milo

Publications and source records attributed to S Milo.

At least 55 records · Page 3Linked to original sources

An experimental study of pressure losses in pulsatile flows through rigid and pulsating stenosis.

The time-dependent pressure curves of a pulsatile flow across rigid and pulsating stenoses were investigated experimentally in a laboratory simulator of the outflow tract of the heart right ventricle. The experiments were performed within the range of physiological conditions of frequency and flow rate. The experimental setup consisted of a closed flow system which was operated by a pulsatile pump, and a test chamber which enabled checking different modes of stenosis. Rigid constrictions were simulated by means of axisymmetric blunt-ended annular plugs with moderate-to-severe area reductions. The pulsating stenosis consisted of a short starling resistor device operated by a pulsating external pressure which was synchronized by the pulsatile flow. It was found that the shape of the time-dependent pressure curve upstream of the stenosis was different in the case of rigid stenosis than in the pulsating one. Potential clinical applications of the work may relate to diagnosis of the type of stenosis in the congenital heart disease known as Tetralogy of Fallot.

Biomechanical Phenomena↗

Discrete membraneous sub-aortic stenosis in adult patient obtained by echocardiography and not proved by catheterization.

A case of a 60-year-old patient with discrete membranous sub-aortic stenosis is described. The diagnosis was established bases on echocardiographic evaluation by demonstration of a premature aortic valve closure and a sub-aortic membrane. No evidence of the sub-aortic membrane was noticed on cardiac catheterization. At operation, a discrete sub-aortic membrane was found 9 mm below the aortic valve, leaving an aperture of 1 cm diameter and a mildly deformed stenotic aortic valve. We stress the importance of careful pre-operative echocardiographic evaluation of every patient suspected of having any kind of left ventricular outflow tract obstruction, even if catheterization data are not contributory.

Aortic Aneurysm↗

Correction of tetrad of Fallot with reduced incidence of right bundle branch block.

In 20 patients who underwent a modified surgical repair of tetrad of Fallot complete right bundle branch block developed in only 8 (40 percent). Standard and intraoperative conduction studies indicated that in these patients the right bundle branch block was due to injury of the right bundle branch near the ventricular septal defect (proximal right bundle branch block). The modified operative technique is aimed at minimizing the injury to the right ventricle and it includes a significantly shorter than usual ventriculotomy incision and avoidance of the septal (moderator) band during infundibulectomy. Intra- and postoperative hemodynamic studies of these patients revealed that relief of the right ventricular outflow obstruction was optimal.

Adolescent↗

Pericardial tamponade and its effect on cardiac performance in absence of the pulmonic valve.

A controlled study was undertaken to quantitate and compare the amount of accumulated pericardial fluid causing acute pericardial tamponade in animals with or without an intact pulmonary valve. In 13 mongrel dogs, acute pericardial tamponade was induced by gradual loading of the pericardial cavity with fluid (mean 21.3 cc/m2). In 10 dogs (Group A) the pulmonic valve was completely excised under caval occlusion and the pericardium resealed. In Group B, the control group (n = 3), caval occlusion was performed for the same period of time but the pulmonary valve was left intact. Reloading of the pericardium with fluid in both groups revealed that whereas in the Control Group B a similar volume of fluid was required (mean 213 cc/m2) to cause critical tamponade, in Group A a much smaller volume (mean 132 cc/m2) (40% decrease) now produced tamponade (p less than 0.001). The results of the study may have important practical implications in patients having cardiac operations in which the pulmonary valve is left incompetent, such as after complete repair of tetralogy of Fallot.

Animals↗

Closed pulmonary valvotomy in infants under 6 months of age: report of 14 consecutive cases without mortality.

Fourteen infants, all under 6 months of age, underwent surgery for the relief of severe valvar pulmonary stenosis. A modified Brock (transinfundibular valvotomy) procedure was performed in all cases. Dilatation of the pulmonary valve with a mosquito clamp and biliary dilator is the basis of the modified operation. All infants survived the operation. In two patients there is residual, significant pulmonary stenosis, and in two additional cases pulmonary regurgitation is present.

Female↗

Aorto-coronary saphenous vein bypass grafting in a patient with a single coronary artery arising from the right aortic sinus.

A patient who presented with severe angina was found to have an ectopic origin of the entire left coronary system, the left main coronary artery arising from the proximal third of the right coronary artery. Atherosclerotic obstructive lesions were present in the right coronary artery, the left anterior descending artery, and the obtuse marginal branch of the left circumflex coronary artery. The three obstructed vessels were bypassed, using autologous saphenous veins. The patient continues to do well 24 months after his operation. We believe that coronary artery bypass should be carried out in symptomatic patients with abnormal coronary anatomy and atherosclerotic disease.

Angina Pectoris↗

Straddling right atrioventricular valves in atrioventricular discordance.

Four hearts are described in which the right atrioventricular valve, draining a morphologically right atrium, straddled and overrode a septum between a right-sided chamber of left ventricular morphology and a left-sided chamber of right ventricular morphology. The degree of override varied between the straddling valve and was committed by 20-45% to the morphologically right ventricle. The ventriculoarterial connections in the hearts were discordant in one, double outlet from the morphologically right ventricle in two and single outlet via an aorta from the morphologically right ventricle with pulmonary atresia in the other. The straddling valve in one of the cases with double outlet had a dual orifice. Pulmonary stenosis was present in three cases, and pulmonary atresia in the fourth. Study of the conduction system in three of the hearts revealed subtle but important differences from the pattern expected in atrioventricular discordance. Each case had an anterior atrioventricular node and penetrating bundle, but the connection thus formed was more lateral than usual, and in the case with ventriculoarterial discordance, the nonbranching bundle was unrelated to the pulmonary outflow tract. A sling of conduction tissue between the anterior node and the regular node was found in the case with single outlet and pulmonary atresia.

Adult↗