Robert C. McKnight

Direct revascularization of bronchial arteries for lung transplantation: an anatomical study.

Direct revascularization of the bronchial arteries for both single-lung and double-lung transplantation would improve airway healing and reduce airway complications after transplantation. We studied the anatomical pattern of bronchial arteries in 30 autopsy cases. In 28 of 30 cases (93.3%), at least one left bronchial artery arose directly from the anterior wall of the descending thoracic aorta. In 25 of the 30 cases (83.3%), at least one right bronchial artery was related to the first right intercostal artery. Injection studies showed that this right intercostobronchial artery supplies the proximal left main bronchus and carina as well as the right bronchus. We developed a technique for extracting the lungs along with the right intercostobronchial artery and a patch of aorta at its origin and applied it to 19 of the dissections. In 17 of the 19 cases studied (89.4%), the right intercostobronchial artery pedicle obtained had a length varying from 6.5 to 8.5 cm, sufficient for attachment of its origin to the ascending aorta of the recipient after double-lung transplantation. The right intercostobronchial artery pedicle provides the possibility for direct bronchial revascularization in right single-lung, double-lung, and lung-heart transplantation. A similar technique, utilizing the left bronchial artery, can be used to revascularize a left lung transplant.

Diagnosis of pulmonary arteriovenous fistula by contrast echocardiography

That the anatomic substrate of the Wolff-ParkinsonWhite syndrome can be inherited without the ECG evidence is illustrated by Family 1. It is likely that the other three families also represent examples of this phenomenon. These findings explain why previous genetic studies have been inconclusive. It was assumed, erroneously, that many subjects did not have Kent bundles when, in fact, they did. It will be difficult to overcome this problem since at present, cardiac catheterization is necessary to find Kent bundles which conduct only in the retrograde direction. If all subjects with PSVT are assumed to have Kent bundles, then false positives may be included since some PSVT might be due to other mechanisms. The mechanism of inheritance of Kent bundles seems to most closely follow that of autosomal dominant with variable expression. This paper has identified one mechanism of the variability. Another might be a patient with a retrograde conducting bundle of Kent who never has PSVT. Orinious et al e reported results which support ours in his 20-year follow-up of 150 members of two families with WPW. Although he found only two additional patients with WPW, he found 17 new examples of SVT, eight of Which were in parent-child combinations. In a patient with PSVT without WPW who has a family member with WPW, a concealed bundle of Kent should be suspected. This finding has obvious therapeutic implications, since patients With concealed bundles of Kent may respond to different medical treatment or may be cured by surgical division of the anomalous pathway. r

Diagnosis of congenital absence of left pericardium by MR imaging.

Congenital absence of the pericardium, whether partial or total, is a rare abnormality. It can be very difficult to diagnose clinically as well as to confirm radiographically. Plain film fluoroscopy and CT have been shown to be of value in differentiating this entity from others with similar findings. We report a case in which magnetic resonance was utilized to confirm the diagnosis and the findings of this new technique are described.

Modification of left ventricular diastolic behavior by isometric handgrip exercise.

To clarify the basis of increased left ventricular (LV) end-diastolic pressure associated with isometric exercise, LV diastolic and systolic function were examined in 25 patients during sustained handgrip. During handgrip, average systemic arterial mean pressure increased by 20 mm Hg, and LV systolic pressure rose by 31 mm Hg, though in five patients, no increase in mean arterial or LV systolic pressure occurred. LV end-diastolic pressure rose by 10 mm Hg, right ventricular systolic and end-diastolic pressures increased by 10 and 5 mm Hg, respectively (p < 0.01 for all pressures). LV end-systolic volume rose by 23%, but end-diastolic volume was unchanged. Reduction of ejection fraction by 13% and mean circumferential fiber shortening rate by 7% indicated further impairment of LV function, though ejection fraction was unchanged or augmented in 14 patients. In all patients, diastolic pressure-volume curves were displaced upward and to the right, without change in the rate constant of the exponentially fit pressure-volume or normalized pressure-volume elasticity relations, operational end-diastolic stiffness or the rate of isovolumic relaxation. Thus, upward transposition of diastolic pressure-volume relations during handgrip does not depend on changes in LV chamber elastic properties or relaxation, LV systolic function or coronary perfusion pressure, but appears, by inference, to be caused by the concomitantly increased right ventricular pressures, perhaps mediated in part by pericardial constraint in association with right ventricular distension.

Insensitivity of echocardiography in detecting mitral valve prolapse in older patients with chest pain

Abstract Although echocardiography has proved useful in detecting mitral valve prolapse, its limitations have not yet been adequately defined. This study was designed to evaluate the prevalence of false negative echocardiograms in patients with angiographically proved mitral valve prolapse. Twelve patients, eight men and four women with a mean age of 47 years, were selected on the basis of the results of cardiac catheterization for chest pain. Each patient had moderate to severe mitral valve prolapse, confirmed angiographically by two observers, with no coronary artery disease or other detectable cardiac abnormalities. Clinically, a systolic click was detected in three patients, a mid-systolic murmur in five, an abnormal electrocardiogram in four and a positive maximal treadmill stress test in two of eight tested. Left ventricular angiograms exhibited anterior and posterior leaflet prolapse in five, and posterior leaflet prolapse alone in seven. High quality echocardiograms were obtained in 11 patients; one record of inadequate quality was excluded. The echocardiograms revealed mitral valve prolapse in only one case, and were “probably” negative in two, and clearly negative in eight. Although these results may reflect the well recognized variable clinical expression of this syndrome, they indicate that false negative echocardiograms are common in this selected older population of patients with angiographic mitral valve prolapse who present with chest pain and few other clinical features. Thus, caution must be exercised in the clinical interpretation of a single echocardiogram negative for mitral valve prolapse.

Late Clinical Problems with Beall Model 103 and 104 Mitral Valve Prostheses: Hemolysis and Valve Wear

The purpose of this study was to determine the influence on hemolysis of the spatial orientation of the struts in the Beall mitral valve prosthesis, Models 103 and 104. Thirteen pairs of patients were selected to match struts oriented parallel and perpendicular to the left ventricular outflow tract axis. The average time after operation was 3.73 years. Complete blood counts and relative serum chemistry values were determined.

Evaluation of congenital heart disease by three-dimensional magnetic resonance imaging.

This study was undertaken to compare electrocardiographically gated magnetic resonance imaging (MRI) to established imaging modalities in the detection of complex intra-and extracardiac morphologic defects. Twenty-three patients with congenital cardiac abnormalities were imaged by four methods: cardiac catheterization, echocardiography, two-dimensional (2D) transaxial MRI, and three-dimensional (3D) MRI surface reconstruction. Observers with experience in congenital cardiac disease diagnosis (two for echo, one for catheterization, two for 2D MR, and three for 3D MR) evaluated the images in a blinded fashion, and the results were analyzed with receiver operating characteristic (ROC) analysis. Overall, cardiac catheterization had the best diagnostic performance. The diagnostic value of routine 2D cardiac MR images and 3D MR reconstruction images were similar to that of echocardiography. All of the modalities performed poorly in the diagnosis of extracardiac defects and atrial septal defects.

The Radiographic Appearance of Coronary Artery Dissection: A Decision-making Dilemma

The appearance of acute iatrogenic dissection of the coronary arteries during coronary angiography is described in five patients. Specific signs of dissection include: 1) intimal flap, 2) delayed flow, 3) loss of side branches, 4) periostial contrast “puddling,” and 5) unusually small size coronary artery with atypical smooth walls.Recognition of the radiographic patterns of this complication should permit distinction from coronary spasm, thrombosis, and embolization. Recent advent of alternate forms of therapy (streptokinase infusion, angioplasty) makes it imperative to precisely diagnose the dissection to avoid possible catastrophic results.

Experimentally Reversed Pulmonary Blood Flow: Implications for the Surgical Management of Complex Forms of Congenital Heart Disease

Blood flow to the right lung was reversed in 28 dogs, 14 of which survived more than 1 month. Four successful long-term survivors (1 years to 4 years 7 months) were repeatedly studied by cardiac catheterization, angiography, and ventilation/perfusion scans as well as hemodynamically when they were killed. Hemodynamics and gas transfer were normal up to 4 1/2 years after the procedure, and the histology of the right lung was essentially normal. The application of reversed pulmonary blood flow is proposed in the surgical management of forms of congenital heart disease in which the right ventricle is diminutive. The procedure consists of repartitioning of the atria to allow venous blood to flow into the lung through the pulmonary veins and exit to the left atrium through the pulmonary artery.

A New Operation for Far-Advanced Cystic Medial Necrosis of the Aortic Root

Three patients with far-advanced cystic medial necrosis of the aorta, which had produced giant bulbous enlargement of the aortic root and severe aortic regurgitation, were operated on using a procedure not previously described. Measurements of the aortic valve annulus and ascending aorta were made from aortograms. A knitted polyester arterial prosthesis was sewn together to form a circle. This circular prosthesis was sewn to a 31 mm Björk-Shiley aortic valve prosthesis in the way that a tire is fitted onto a wheel. The resulting composite prosthesis, which had the same diameter as the aortic root, was used to replace the excised valve. In all cases a composite prosthesis measuring greater than 50 mm in diameter was used. In 2 of the 3 patients the ascending aorta was replaced with a tubular graft reshaped as a truncated cone. This reshaping was done by inserting multiple gussets into one end of the aortic prosthesis so that the flanged end fit precisely to the transverse aortic arch. Two patients are asymptomatic more than two years following operation. The third patient died suddenly of a ventricular arrhythmia on the twenty-third postoperative day.