David S. Leighninger

Chronic effects of aorta-coronary sinus anastomosis of Beck in dogs.

Studies were made on dogs at various times up to one year following the coronary sinus anastomosis of Beck to determine the chronic effects of the operation. The results indicate that the graft perfuses the capillary bed of the occluded circumflex artery for about five weeks after the operation and then loses its functional contact with the capillary bed probably because of obliterative venous changes. However, as a result of an anoxia, there is definite development of intercoronary collateral vessels during the first few weeks, which persist throughout the year even though there is no arterial occlusion. It is concluded that in dogs the Beck operation is protective against the major effects of coronary ligation because of retrograde capillary flow early and intercoronary anastomoses later.

Effect of pentaerythritol tetranitrate, amyl nitrite and alcohol on arterial blood supply to ischemic myocardium

Abstract 1. 1. Treatment of localized myocardial ischemia depends upon addition of arterial blood by way of intercoronary arterial communicacations. 2. 2. Pentaerythritol tetranitrate adds 0.81 cc. per minute to the ischemic circumflex area of the dog heart. 3. 3. Amyl nitrite adds 0.98 cc. per minute to the ischemic circumflex area of the dog heart. 4. 4. Alcohol decreases intercoronary flow by 1.93 cc. per minute. 5. 5. Increased intercoronary flow resulting from drug action is temporary. 6. 6. Addition of 0.81 cc. per minute as produced by pentaerythritol tetranitrate did not reduce mortality or infarct size following test coronary artery ligation in a series of twentyone experiments.

LEFT HEART BYPASS IN CARDIAC RESUSCITATION.

Abstract 1. 1. In the presence of ventricular fibrillation, left heart bypass increases systolic and diastolic blood pressures by 20 to 100 mm. Hg and thus augments the blood supply to anoxic tissues. 2. 2. After coronary artery ligation, bypass delays the onset of ventricular fibrillation. 3. 3. Defibrillation is facilitated under conditions of left heart bypass. 4. 4. This evidence supports the use of left heart bypass as an aid in resuscitation from cardiac arrest.

Infarction of The Right Ventricle Caused by Multiple Coronary Vein Ligation

Ligation of the coronary sinus and all the visible anterior cardiac veins led to death in 5 out of 24 dogs. In 15 out of 17 of these dogs coming to autopsy, varying degrees of infarction of the right ventricle were found. The work emphasizes the importance of the superficial venous system in the drainage of the myocardium and reveals the inadequacy of the intramural system when the latter is forced to assume the entire outflow load.

Intercoronary arterial channels produced by chemical agents

V ASCULAR communications between coronaq arteries protect the heart when stenosis or occlusion of these arteries takes place. These channels “ration” the available blood and deliver it to ischemic muscle where it is needed most. Theyhave significant protective value. The Beck operation was designed to produce such intercoronary channels.lP4 One of the methods to produce them consisted of abrasion of the surface of the heart. In some instances abrasion cannot be done because the heart is too irritable. In such cases a substitute method, such as the use of a chemical agent, is desirable. Experiments with \.arious chemical agents arc reported here.

Further observations on aorta to coronary sinus anastomosis of Beck in dogs.

Summary 1. Measurements of retrograde circumflex artery flow, peripheral coronary artery pressure, and electrocardiographic changes induced by circumflex artery ligation were evaluated in an additional 5 Beck #2 operated dogs. 2. Twenty-six Beck #2 operated dogs studied from 4 weeks to one year after the second stage of the operation have been compared with: 1) 41 control dogs, 2) sham Beck #2 operated dogs, 3) defibrillated dogs, and 4) Beck #2 operated dogs 3 months after ligation of the graft. 3. Beck #2 operation results in a significant development of intercoronary arterial communications which persist for at least one year in the presence of a functioning graft and for at least 3 months after ligation of the graft. 4. Sham Beck #2 operated dogs develop intercoronary arterial communications which is in contrast to the lack of such communications following ventricular defibrillation. 5. Further substantiation is provided for previous evidence that in a majority of the Beck #2 operated dogs both functional and anatomical contacts between the perfused venous system and a capillary bed are eventually lost. Consequently earlier conclusions are supported that after about 5 weeks the Beck #2 operation protects normal dogs from the effects of coronary artery ligation by means of intercoronary arterial communications.

Ligation of internal mammary arteries as related to the coronary artery circulation

L IGATION of the internal mammary arteries for treatment of angina pectoris and coronary heart disease has been discussed in many publications. Reference to these publications is omitted from this paper. Only our experiments are reported. Various tests were established in our laboratory to measure the beneficial effect of a drug or a surgical operation upon the coronary artery circulation. These tests are as follows: (1) backflow measurements; (2) electrical fibrillation (mortality) after test artery occlusion; (3) size of infarct after test artery occlusion and (4) the electrical condition of the heart after test artery occlusion. Each of these tests is related to the amount of oxygenated (arterial) blood delivered to an area of ischemic muscle. When the amount of blood to an area of ischemic muscle is increased by therapy, the condition is improved ; when it is reduced, the opposite effect is produced. These statements apply to both the human subject and the experimental dog. The effect of ligation of the mammary arteries on these tests has been studied.

Surgical Procedure for Coronary Arterial Disease

1 Presented at the first annual meeting of the American College of Angiology at Atlantic City, New Jersey on June 4, 1955. 2 Western Reserve University and the University Hospitals, Cleveland, Ohio. This work was supported by grants from the United States Public Health Service and the Cleveland Area Heart Society. Beck and his associates demonstrated the principles of surgically improving the blood supply to the heart (1). These principles are based on the results of direct manipulation of the coronary circulation in about 5000 dogs during the past 23 years, and these principles have been applied to 253 patients during the past 20 years. The surgical treatment of coronary arterial disease is based upon three considerations :