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Biomedical subjects

J R Zuberbuhler

Publications and source records attributed to J R Zuberbuhler.

At least 55 records · Page 3Linked to original sources
PubMed1985

A percutaneously adjustable device for banding of the pulmonary trunk.

An optimal result is often difficult to obtain with conventional banding of the pulmonary trunk. Furthermore, this procedure has a significant surgical morbidity and mortality. An inflatable device has therefore been developed which consists of an inflatable band and a valve. The band is made of a silicone balloon which is covered with reinforced braid. The band is applied loosely around the pulmonary trunk through a left lateral thoracotomy. The valve is implanted subcutaneously in an intercostal space. The size of the band can be adjusted postoperatively using a needle and fluid-filled syringe percutaneously to inflate or deflate the balloon. Experiments were conducted in 5 animals and follow-up evaluation by cardiac catheterization and angiocardiography was made up to 4 months after implantation of the device. The band could be effectively and reliably adjusted and no malfunction or complication occurred. This preliminary study suggests that this new technique may make banding of the pulmonary trunk a more reliable and effective procedure and may reduce surgical morbidity and mortality. It also may avoid or delay subsequent additional surgery for revision of a band which is too tight or too loose.

Animals↗
PubMed1985

Ventricular septal defect associated with aneurysm of the membranous septum.

The most common variety of ventricular septal defect, a perimembranous defect, is frequently associated with a so-called aneurysm of the membranous septum. Previous studies have suggested that ventricular septal defects associated with an aneurysm of the membranous septum tend to spontaneously decrease in size or close more than defects without such an aneurysm. To better define the natural history of this entity, clinical and catheterization data from 87 patients with ventricular septal defect and aneurysm of the membranous septum were reviewed. The initial evaluation was made at a median age of 0.3 years (range 0.1 to 11), with the final evaluation at a median age of 10 years (range 1.5 to 20) and a median duration of follow-up of 8.6 years (range 1.2 to 18.8). Approximately 75% of the ventricular septal defects had a small or no left to right shunt at last evaluation. Overall, 48 patients (55%) had no significant change in the size of the defect, and 39 (45%) showed improvement during the period of observation. Only four patients (5%) had spontaneous closure of the defect. Of the 49 patients who presented with a large left to right shunt, with or without congestive heart failure, 23 (47%) had persistence of a shunt large enough to warrant surgery. When spontaneous improvement occurred, it did so by 6 years of age in all but one patient. Therefore, a continued tendency for a ventricular septal defect associated with an aneurysm of the membranous septum to spontaneously decrease in size or close after this age may be less likely than previously suggested.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm↗
PubMed1985

Atrioventricular septal defect with balanced ventricles and malaligned atrial septum: double-outlet right atrium. Report of two cases.

An unusual form of atrioventricular septal defect was found at operation. The anatomy was that of a primum atrial septal defect with deviation of the atrial septum to the left. Thus from the right atrium both right and left atrioventricular valves could be seen. The left-sided valve was tricuspid. Repair was achieved by closure of the septal commissure of the left-sided valve ("cleft"), excision of the lower part of the atrial septum, and insertion of a pericardial patch. The lower part of the patch was sutured between the left and right atrioventricular valves. A specimen with similar anatomy is also described.

Child, Preschool↗
PubMed1985

Of clefts, commissures, and things.

A full understanding of the morphology of atrioventricular septal defects ("endocardial cushion defects," "atrioventricular canal malformations") demands knowledge of the exact nature of three specific breaches in the skirt of valve leaflet tissue guarding the atrioventricular junction. One of these is the space between the left ventricular components of the two leaflets that are enclosed in both the right and left ventricles (the bridging leaflets). Traditionally described as a cleft, it has been suggested more recently that this gap functions as a commissure. The second space is that which is found anteriorly and superiorly in the so-called Rastelli type A malformation. This is also called a cleft in a common anterior leaflet, but it has been suggested that it too is a commissure. The final breach is that produced by the surgeon when he divides the free-floating superior bridging leaflet if repairing the so-called Rastelli type C malformation with a one-patch technique. It is generally agreed that this breach be considered a division. To adjudicate the nature of the other breaches, it is necessary to compare them with commissures in atrioventricular and arterial valves and with the isolated cleft that exists in the aortic leaflet of a normal mitral valve. These considerations show that the gap between the left ventricular components of the bridging leaflets functions as a commissure even though it is not supported by a papillary muscle. This would not be expected, since the commissural attachments of the leaflets are in the left and right ventricle, respectively. The gap seen anteriorly in the Rastelli type A malformation is also a commissure, being supported in typical fashion by the medial papillary muscle of the right ventricle.

Heart Septal Defects↗
PubMed1985

Further observations on the morphology of atrioventricular septal defects.

Certain morphologic aspects of atrioventricular septal defects ("endocardial cushion defects," "atrioventricular canal malformations") remain controversial. It is still not clear which precise lesions should not be placed in this category. For example, is an "isolated" cleft of the mitral valve or a perimembranous inlet ventricular septal defect to be so described? It is also not fully accepted that the left atrioventricular valve in these lesions bears little resemblance to a morphologically mitral valve. We have investigated these problems by both observation and mensuration. We determined the junctional circumference of the left atrioventricular valve leaflets and the ventricular dimensions in 130 atrioventricular septal defects (95 with common valve orifice and 35 with separate right and left atrioventricular orifices); in 50 hearts with perimembranous ventricular septal defects (20 extending into the inlet septum and 30 with outlet or trabecular extensions); in seven hearts with isolated cleft of the mitral valve, and in 10 normal hearts. All specimens came from the cardiopathological collection of Children's Hospital of Pittsburgh. The measurements showed conclusively that the atrioventricular septal defects were all directly comparable irrespective of the detailed morphology of the atrioventricular valve or valves. The group of atrioventricular septal defects was totally discrete as compared with all the other specimens that had normal atrioventricular septation. The left atrioventricular valve in atrioventricular septal defects is basically a three-leaflet valve which differs from the normal mitral valve in terms of its leaflet, its chordal support, and the arrangement of its papillary muscle. Its only similarity with the normal mitral valve is that it resides in the morphologically left ventricle and guards the left atrioventricular junction.

Child↗
PubMed1984

Surgical management of univentricular heart with subaortic obstruction.

In children with a univentricular heart and a rudimentary subaortic chamber, surgical relief of subaortic obstruction caused by a restrictive bulboventricular foramen is associated with high morbidity and mortality. A 6-year-old child with a univentricular heart of the left ventricular type, a rudimentary subaortic chamber, and atresia of the left-sided atrioventricular valve had pulmonary artery banding in infancy. Severe subaortic obstruction subsequently developed. At operation, the pulmonary artery was transected and the stump was anastomosed directly to the posterior aspect of the ascending aorta, diverting left ventricular blood into the aorta through the pulmonary valve. The distal pulmonary artery was anastomosed side-to-side to the ascending aorta to provide pulmonary blood flow. Cardiac catheterization fifteen months after the operation demonstrated an excellent hemodynamic result. When the pulmonary artery is adequate in size, a bypass operation by way of an anastomosis between the ascending aorta and the pulmonary artery is a relatively safe and effective means of relieving the ventricular outflow obstruction caused by a restrictive bulboventricular foramen.

Aortic Valve Stenosis↗
PubMed1984

Ventricular inversion with normal ventriculoarterial connection and left atrial isomerism: correction by the Mustard operation.

A 2 year old boy with ventricular inversion and normal ventriculoarterial connection is described. Associated cardiac lesions included single atrium, absence of the coronary sinus, bilateral superior venae cavae, absence of the hepatic segment of the inferior vena cava with azygos and hemiazygos continuation, right aortic arch, levocardia and left atrial isomerism. At 5 days of age, the patient underwent a Waterston (aortopulmonary) anastomosis because of suspected pulmonary atresia. The correct diagnosis was established at 2 years of age and the patient had a successful Mustard operation (interatrial baffle procedure) and closure of the Waterston anastomosis. Accurate preoperative diagnosis is difficult in this rare cardiac anomaly and the reported mortality rate is high.

Cardiac Catheterization↗
PubMed1984

The morphology of ventricular septal defects.

Ventricular septal defect (VSD) is the most common congenital cardiac lesion, occurring either in isolation or in hearts containing more complex lesions. Usually, the defect is between two ventricles, each of which is connected to a separate atrium and to a separate great artery, and surgical or spontaneous closure of the VSD basically corrects the circulation if the effects of any associated lesion are ignored. In other situations, the VSD is an integral part of the circulation, either because the atria connect to only one ventricle or because the ventricles give rise to only one patent great artery or else both great arteries arise from the same ventricle. When in such circumstances the circulation is VSD-dependent and the defect cannot be surgically closed without bypassing it with a conduit or similar device. In all of these situations, the VSD takes one of three basic forms. Usually, the VSD abuts directly upon the fibrous skeleton of the heart formed by the conjoined rings of the cardiac valves. The membranous part of the ventricular septum is an integral part of this skeleton, and these defects are termed perimembranous. These defects do not always occupy the same part of the septum. They may extend mostly into either the inlet, trabecular, or outlet parts of the muscular septum, or else be confluent extending into two or all these parts. Less commonly, VSD may be exclusively contained within the muscular septum. Such muscular defects can also be confined to either the inlet, trabecular, or outlet parts of the septum. They may be multiple or coexist with one of the other types. The third and least common type is a VSD which is roofed by the conjoined rings of the aortic and pulmonary valves because of absence of the outer septum. Such a defect may have a muscular posteroinferior rim or may extend to become perimembranous. Identifying a defect as perimembranous or muscular, together with its location relative to the different parts of the muscular septum, gives at the same time information concerning the site of the conduction axis in relation to the defect and its chances of spontaneous closure.

Aorta↗
PubMed1983

Double-inlet left ventricle with rudimentary right ventricle and ventriculoarterial concordance.

Seven hearts were studied that had in common the segmental combination of double-inlet left ventricle, rudimetary right ventricle and ventriculoarterial concordance. The prototype of these hearts has been described as the "Holmes heart" or "single ventricle type A1." Five of the hearts had 2 atrio-ventricular valves; in 1 of these the right valve was minimally straddling. The other 2 had a common valve. In 6 of the hearts the rudimentary right ventricle was obliquely situated on the anterior surface of the dominant left ventricle. The trabecular component was anterior and right-sided with the outlet components and pulmonary trunk in left-sided position. In the final case, both trabecular and outlet components of the rudimentary right ventricle were left-sided. Conduction tissue studies were performed in 2 hearts. In 1, the connecting atrioventricular node and bundle were in anomalous anterolateral position, as expected in double-inlet left ventricle. In the other, a ring-like, posterior, nonbranching bundle connected the regular node in the atrial septum to the branching bundle positioned on the anterior interventricular septum. The anatomic findings are related to the likely modes of presentation and differential diagnosis while the conduction tissue findings are discussed in the light of options for surgical repair. Thus, the term "single ventricle" is best avoided when describing hearts that unequivocally possess 2 ventricular chambers.

Heart Conduction System↗
PubMed1983

Hemodynamic function after the Mustard operation for transposition of the great arteries.

Pre- and postoperative cardiac catheterization data and cinenangiocardiograms of 82 patients who survived the Mustard operation for transposition of the great arteries (TGA) were reviewed. The post-operative catheterizations were performed 20 days to 10 years after operation (mean 2.5 years). Forty-six patients (56%) had no or insignificant associated cardiac lesions, whereas 36 (44%) had ventricular septal defect, pulmonary stenosis, or both, and required surgical intervention at the time of the Mustard operation. Postoperatively, 11 patients (13%) had significant systemic venous obstruction. Of the 11 patients, 6 required reoperation, and 2 patients had evidence of restenosis or complete obstruction in the superior vena cava after reoperation. In most patients, superior vena caval obstruction was well tolerated even in the presence of high pressure in the superior vena cava. Pulmonary venous obstruction occurred in 5 patients (6%), 3 of whom had no clinical symptoms despite severe pulmonary venous obstruction, although all had radiographic evidence of pulmonary venous congestion. The incidence of obstruction was drastically reduced after the Mustard operation was modified to include routine enlargement of the pulmonary venous atrium. Tricuspid regurgitation was uncommon (10%), but did occur in patients who had transatrial closure of a ventricular septal defect. Preoperatively, left ventricular outflow obstruction occurred in 38%. In 12 patients an attempt was made to relieve the obstruction at surgery. The 6 patients who had localized obstruction had a good result, but patients with more diffuse narrowing of left ventricular outflow had little or no relief of obstruction. Mild to moderate left ventricular outflow gradients regressed spontaneously in most patients after the Mustard operation.

Adolescent↗
PubMed1983

Rest and exercise right and left ventricular function late after the Mustard operation: assessment by radionuclide ventriculography.

To evaluate ventricular function late after atrial repair of transposition of the great arteries (TGA), 26 asymptomatic patients had rest and exercise radionuclide ventriculography performed a mean of 9 years (range 5 to 15) after undergoing the Mustard operation. The mean resting right (systemic) ventricular (RV) ejection fraction (EF) was 0.50 +/- 0.10 (+/- 1 standard deviation); the RVEF was less than 0.45 in 8 patients. With exercise the RVEF increased in 9 patients and either failed to increase or decreased in 15 (including all 8 patients with resting values less than 0.45). The weight-adjusted work load performed was a first predictor of RV exercise response (sensitivity 87%, specificity 92%); patients whose RVEF increased did more work. The mean resting left (pulmonary) ventricular (LV) EF was 0.58 +/- 0.09; the LVEF was less than 0.50 in 3 patients. With exercise the LVEF increased in 14 patients and did not increase in 10 (including all 3 with resting values less than 0.50). The presence of complex ventricular arrhythmia documented on Holter monitoring was a first predictor of failure of the LVEF to increase with exercise (sensitivity 84%, specificity 71%). The patient's age, operative age, postoperative interval, residual arterial desaturation, preoperative large ventricular septal defect or pulmonary stenosis, postoperative pulmonary stenosis or superior vena caval obstruction, or performance of a second open-heart procedure was predictive of the rest or exercise EF of either ventricle.

Adolescent↗
PubMed1983

Exercise studies after the Mustard operation in transposition of the great arteries.

Twenty-one postoperative patients with transposition of the great arteries (TGA) underwent graded exercise testing 4 to 15 years (mean 9) after the Mustard operation. No patient had subjective exercise intolerance before testing, although some had symptomatic resting arrhythmias. Correlations were made between cardiac catheterization data and 24-hour ambulatory monitoring. Exercise tolerance was diminished in nearly half of the patients. No statistically significant differences were found in heart rate or blood pressure responses, but maximal oxygen consumption values were lower than the control values (p less than 0.001) in the larger patients. Arrhythmias were present or provoked in most patients during exercise testing. Only 28% remained in normal sinus rhythm during and after exercise. Multifocal premature contractions were the most serious arrhythmias demonstrated. Some long-term survivors of the Mustard operation may have abnormal exercise dynamics, even though they may be asymptomatic and have normal physical activities and endurance. Mean maximal systolic blood pressure, heart rate, oxygen consumption, and maximal treadmill times were consistently in the low-normal range or were statistically lower than normal.

Adolescent↗
PubMed1983

Arrhythmias in transposition of the great arteries after the Mustard operation.

Disorders of rhythm or conduction in patients with transposition of the great arteries (TGA) after the Mustard operation have been widely reported. This study provides a systematic evaluation of the electrophysiologic function of 87 survivors of the Mustard operation at a single institution. Surface electrocardiograms were reviewed in all 87 patients, Holter monitoring data in 26 patients, exercise electrocardiograms in 21 patients, and invasive electrophysiologic data in 61 patients. Surface electrocardiograms showed normal sinus rhythm in 52%, sinus node dysfunction in 27%, and atrioventricular block in 16%. Holter monitoring was obtained in an unselected subgroup of 26 patients who had a mean age of 12 years and a mean interval from operation of 9 years. Sinus node dysfunction was found in 58%, atrioventricular block in 27% ventricular ectopy in 50%, supraventricular ectopy in 27%, and no abnormalities in only 8%. Intracardiac electrophysiologic evaluation showed a high frequency of abnormal sinus node recovery times and suboptimal response of the atrioventricular-conduction system to rapid atrial pacing. When all modalities used in this study were considered, sinus node dysfunction occurred in 47%, ectopy in 34% and atrioventricular block in 23%. Although only 30% of patients had no evidence of arrhythmia, symptoms of rhythm or conduction disturbances were rare.

Adolescent↗
PubMed1983

Mechanisms of closure of perimembranous ventricular septal defect.

Although more defects in the muscular ventricular septum close spontaneously than do defects abutting on the membranous septum (perimembranous defects), a good proportion of the latter show a tendency to diminish in size and to close. The mechanism responsible for this closure is usually described as an aneurysm of the membranous septum, although some doubt has been cast as to whether this is the precise mechanism. In this study, 69 unoperated hearts with ventricular septal defect were examined; 26 (38%) showed some evidence of partial closure and none extended exclusively into the outlet part of the septum. Two thirds of the trabecular perimembranous defects, almost half of the inlet defects, and one third of the confluent defects showed signs of partial occlusion. The anatomic structures most frequently responsible were reduplication of tricuspid valve tissue (16 cases), adhesion of tricuspid valve leaflets (6 cases), and prolapse of an aortic valve leaflet (3 cases). Only in 2 cases were subaortic tissue tags observed which might have originated from the remnant of the membranous septum. The present study shows that although anatomic evidence of partial closure was present in two fifths of the hearts studied, only rarely was it due to so-called aneurysm of the membranous septum.

Aortic Valve↗