Biomedical subjects
Publications and source records attributed to J R Allard.
A technique for producing valvar aortic stenosis is described. The noncoronary sinus of Valsalva is plicated externally at a level proximal to the origin of the coronary arteries. The major intraoperative problems are hemorrhage, acute left ventricular failure, and heart block, all of which can be avoided. The survival rate in 26 dogs was 54% and all the survivors remained active. Moderate left ventricular hypertrophy was produced.
To determine whether left ventricular hypertrophy [LVH] altered total and regional coronary blood flow, we inflated a balloon around the ascending aorta of nine dogs; six acute and six sham-operated dogs were controls. After 6 weeks, all dogs were studied with an open chest under anesthesia; the balloons were deflated. There was moderate LVH as shown by increased left ventricular weight and fiber diameter. At rest there were no major differences of coronary flow or resistance per gram of muscle. With maximal coronary vasodilation due to adenosine or carbochrome, mean coronary vascular resistance was 84% higher in LVH than in normal hearts; with isoproterenol, resistance was 54% higher in LVH. These changes were similar in right and left ventricles. Minimal coronary resistance at end diastole also was higher in LVH--64% and 94% for the two sets of vasodilators, respectively. There were no significant differences in capillary or large vessel proportional volumes in LVH and control dogs, but arterial capacity could not be estimated. The raised minimal coronary resistance suggests the possibility that, with stress, coronary flow, especially to subendocardial muscle, might be inappropriate and perhaps cause ischemic damage. However, the changes noted might have been due to coronary arterial responses to raised coronary pressures rather than to hypertrophy itself.
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From January, 1969, to June, 1974, 11 infants with interrupted aortic arch were operated upon. Eight of them died in the perioperative period. Their cases were reviewed in an attempt to find factors influencing the prognosis. Age, weight, preoperative hemodynamics, angiographic findings, and the type of arch anomaly did not influence the outcome. The operation, whether palliative or involving intracardiac repair, did not affect the prognosis. The only factor related to the outcome was the size of the conduit: in all infants who died, the vessel used to bridge the gap (carotid or subclavian artery) was of narrow diameter. In the 3 patients who survived it was of much larger bore. We conclude that in the repair of interrupted aortic arch, an adequate conduit is essential for success.
To ascertain the frequency and probable determinants of myocardial infarction after aortocoronary bypass, two groups of patients were studied: a group of 20 patients who underwent valve replacement of repair of congenital anomalies and a group of 24 patients who underwent aortocoronary bypass. Postoperative myocardial infarction was diagnosed by an increase in serum creatine phosphokinase concentration to a minimum of 1200 IU in two consecutive samples. The frequency of myocardial infarction differed between the groups, being only 5% in group 1 but 20.4% in group 2. In the patients undergoing coronary artery surgery, the duration of bypass, the aortic cross-clamp time and the vent site did not influence the rate of infarction. However, the incidence of myocardial necrosis did correlate with the number of vessels bypassed. In no case was the clinical course influenced by the infarction. Our results suggest that the frequency of perioperative infarction is higher in coronary artery surgery than in other adult cardiac surgery, and that the most important determining factor is the number of diseased vessels.
Ten months after aortic valve replacement (Björk-Shiley prosthesis) a 57-year-old man had thrombotic encapsulation of his prosthetic valve. The only clinical manifestation of this serious complication was gross hemoglobinuria. The management of the patient is described. The slightest change in the condition of a patient after prosthetic valve replacement should be viewed as a possible sign of thrombosis.