Robert K. Brawley

Feasibility and Effectiveness of Low-Energy Catheter Defibrillation in Man

The effectiveness of low energy intraventricular catheter defibrillation was evaluated in 11 patients undergoing coronary artery surgery, in whom ventricular fibrillation occurred after anoxic arrest of 21-42 min. A distal electrode catheter was introduced through an atriotomy into the right ventricular apex. In eight patients the proximal electrode was a saline-soaked sponge placed on the superior vena cava, while in three this electrode formed an integral part of the superior vena cava cannula used in cardiopulmonary bypass. Intraventricular catheter defibrillation was accomplished in nine patients using 5-15 w-sec, considerably less energy than required for paddle defibrillation. There were no apparent short or long-term ill effects. Unsuccessful defibrillation in the two remaining patients was ascribed to difficulties in electrode placement. The effectiveness of low energy intraventricular catheter defibrillation in man, in addition to raising basic electrophysiologic questions, provides background for the development of the transvenous automatic defibrillator for protection of selected high-risk patients.

Routine Use of Autotransfusion Following Cardiac Surgery: Experience in 700 Patients

An autotransfusion technique has been developed for collection and reinfusion of shed mediastinal blood. This system has been routinely applied in the postoperative management of 592 consecutive adult and 108 pediatric cardiac surgical patients. Two hundred seventy-one adult patients (46%) and thirty-six pediatric patients (33%) actually received autologous blood. Autotransfusion volume ranged from 50 to 21,350 ml per patient. In 1976 at our institution, homologous transfusion requirements averaged 8.4 +/- 0.7 units per adult patient. During 1978, with the routine use of postoperative autotransfusion, bank blood transfusions were lowered to 4.2 +/- 0.3 units per patient (p less than 0.001). In contrast to perioperative autotransfusion techniques, collection and reinfusion of shed mediastinal blood is particularly useful for intravascular volume replacement in patients with serious postoperative bleeding.

The Heparin-coated Vascular Shunt for Thoracic Aortic and Great Vessel Procedures: A Ten-Year Experience

From 1966 to 1976 a flexible, heparin-coated shunt was used for operative procedures on the thoracic aorta and great vessels in 25 patients aged 15 to 78 years. Twenty patients had resection of aneurysms of the descending thoracic aorta. There was 1 death in 15 patients undergoing elective resection and 2 deaths (both from rupturing aneurysms) in 5 patients having emergency resection. The shunt was used in 5 patients who had procedures involving involving the great vessels. There have been no complications attributable to the shunt in either group. The advantages of this shunt include elimination of the need for systemic heparin, avoidance of hypertension during cross-clamping, and adequate perfusion of the distal cirulation without an interposed pump. Because of the ease of handling, low risk, and versatility, we consider the use of this shunt the preferred method for support in elective procedures of the thoracic aorta and great vessels.

Hemodynamics of Aorta-to-Coronary Artery Bypass: Experimental and Analytical Studies

Abstract Aorta-to-coronary artery vein bypass was accomplished in 15 dogs. Flow in the graft and proximal coronary artery was measured with an electromagnetic flowmeter. The partition of flow was found to be dependent on (I) the graft-to-artery diameter ratio (D g /D a ) and (2) the degree of stenosis present in the proximal coronary artery. With an unobstructed proximal coronary artery, small grafts (D g /D a g /D a ≥ 2.0) carried 95.1% of the total flow. When a short, 50% stenosis was placed on the proximal coronary artery, the graft always carried more than 90% of the total flow. Simple calculations based on Poiseuilles law provide results which agree closely with the experimental data. These data imply that thrombosis of the proximal coronary segment may well be expected following aorta-to-coronary artery bypass due to the small amount of flow in this vessel. Experimental data and calculations show that the velocity of graft flow decreased as the D g /D a ratio increased. With a D g /D a ratio decrease from 3.0 to 1.5, the graft velocity rose by as much as 320%. This indicates that in clinical coronary bypass there may be considerable advantage in using a small-diameter bypass vessel (either distal saphenous vein or internal mammary artery) to insure a higher velocity flow through the graft.

Improved Exposure of the Mitral Valve in Patients with a Small Left Atrium

A modification of the usual approach to the mitral valve is described and illustrated. This technique employs right atriotomy and interatrial septotomy, which can be easily performed when standard left atriotomy does not provide satisfactory mitral valve exposure. While this modification is not often necessary, it can be helpful in patients with a small left atrium, especially those with a small left atrium and associated left ventricular hypertrophy.

Clinical and Hemodynamic Evaluation of the 19 mm Bjork-Shiley Aortic Valve Prosthesis

Between November, 1973, and March, 1980, 43 patients underwent isolated aortic valve replacement with 19 mm Björk-Shiley prostheses at the Johns Hopkins Hospital. There were 4 male and 39 female patients ranging from 12 to 75 years old (mean, 54.5 years). Average weight was 62 +/- 2 kg and average body surface area, 1.64 +/- 0.3 m2. Five patients died within thirty days of operation; however, since 1975, hospital mortality has been 5.9%. The 38 survivors have been followed up for as long as 85 months (mean, 40 months). There were 4 late deaths, and actuarial survival in patients discharged from the hospital was 81% at five years. All long-term survivors were in New York Heart Association Functional Class I (29 patients) or Class II (5 patients). Preoperative and postoperative echocardiograms in 17 patients demonstrated significant decreases in mean left ventricular wall thickness (12.9 +/- 1.8 mm vs 10.3 +/- 1.4 mm; p less than 0.001) and in left ventricular mass (262 +/- 95 gm vs 188 +/- 50 gm; p less than 0.02). Postoperative cardiac catheterization data were obtained from an additional 24 patients undergoing aortic valve replacement with the 19 mm Björk-Shiley prosthesis at the National Heart Institute. Average peak systolic gradient at rest was 16 mm Hg (range, 0 to 45 mm Hg) and was found to be directly related to body surface area (r = 0.60, p less than 0.002). Average effective valve orifice area was 1.06 cm2 (range, 0.63 to 2.02 cm2). For patients with small aortic roots, aortic valve replacement with the 19 mm Björk-Shiley valve is a satisfactory and, perhaps, preferable alternative to aortic annuloplasty to accommodate larger sized prostheses.

Current status of the Beall, Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter cardiac valve prostheses.

The Starr-Edwards ball valve prosthesis is generally the standard by which other cardiac valve substitutes are compared. This report reviews information pertaining to several prostheses--the Beall mitral valve and the Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter aortic and mitral valves--considered by some to have specific advantages over the Starr-Edwards valves. Hospital and late mortality rates after valve replacement are comparable for the four aortic valve prostheses reviewed and depend more on patient selection than on the specific prosthesis utilized. Extensive clinical experience with the Bjork-Shiley aortic valve indicates that this prosthesis offers hemodynamic advantages over ball valve prostheses, especially in patients with a small aortic root. Clinical experience with the Lillehei-Kaster pivoting disc prosthesis has been less extensive, but this model provides theoretical hemodynamic advantages similar to those of the Bjork-Shiley aortic valve prosthesis. Problems associated with cloth wear and the unexpectedly slow rate, in man, of tissue ingrowth into the fabric of the Braunwald-Cutter aortic valve prosthesis have been discouraging, although this prosthesis has been associated with a very low thromboembolic rate in patients receiving anticoagulant therapy. The Smeloff-Cutter aortic prosthesis is hemodynamically similar to the Starr-Edwards prosthesis and has been proved to be a reliable and durable aortic valve substitute over the past several years. Mortality after mitral valve replacement is also largely influenced by factors other than prosthetic valve design. On the basis of postoperative data, the five mitral valve prostheses reviewed do not appear to have substantial hemodynamic differences. For patients with a small left ventricular cavity the low profile prostheses, such as the Beall, Bjork-Shiley and Lillehei-Kaster, may be advantageous. Most available evidence indicates that patients receiving aortic or mitral valve prostheses should be given anticoagulant therapy postoperatively.

Long-Term Evaluation of Tetralogy Patients with Pulmonary Valvular Insufficiency Resulting from Outflow-Patch Correction Across the Pulmonic Annulus

In the operative correction of tetralogy of Fallot with a severely narrowed right ventricular outflow tract, widening of the pulmonic annulus is frequently necessary to prevent a high residual pressure gradient and to reduce right ventricular pressure overload. This can be accomplished by incising the pulmonic annulus and inserting a patch graft across the valve, but this usually results in pulmonary valvular insufficiency.Of 426 patients who underwent total correction of Fallots tetralogy between 1959 and 1970, 63 required a patch across the pulmonic annulus. The mortality rate for this group was 30.1%, compared with a total mortality among the 426 patients of 18%. The high mortality rate is influenced by the fact that the majority were corrected in the early years of the series.Fifteen patients were restudied by cardiac catheterization and cineangiography an average of 9.1 years after total correction. Twelve patients were asymptomatic and three patients had only mild symptoms on exertion in spite of angiographically significant pulmonic regurgitation. The average right ventricular systolic pressure was 40 mm Hg; right ventricular end-diastolic pressure was 7 mm Hg; and the right ventricular/pulmonary arterial peak systolic pressure gradient was 14.9 mm Hg. This experience suggests that after a more difficult immediate postoperative period, patients who have right ventricular outflow reconstruction with patches across the pulmonic ic annulus tolerate their chronic pulmonic regurgitation very well.

Permanent Cardiac Pacemakers in Children: Technical Considerations

Placement of permanent cardiac pacemakers in children presents technical problems that are not encountered in the adult. Problems unique to pacemaker implantation in children are related to the patients size, the relative bulkiness of pulse generators, the lack of subcutaneous tissue, and the childs growth and long life expectancy. Based on our experience with implantation of 27 permanent cardiac pacemakers in 13 children, we have found that the use of small pulse generators, placement of epicardial leads, insertion of properitoneal pulse generators, and use of recharabeable pacemakers are satisfactory methods in children.

Factors influencing survival following postinfarction ventricular septal defects.

Postinfarction ventricular septal defect (VSD) carries a grave prognosis. Surgical closure appears to improve survival. Eighteen patients with postinfarction VSD are reviewed. Nine died before operation could be performed and 9 underwent closure of the VSD; 4 patients are late survivors. Factors which appear to influence survival are: (1) time of surgical intervention after appearance of VSD, (2) presence or absence of cardiogenic shock, (3) location of the infarct, and (4) operative approach to the VSD. Based on these factors, a method of management for postinfarction VSD is outlined.