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The mortality rate in patients developing heart failure and shock following a myocardial infarction is as high as 60% to 90%. Mechanical support of the heart by assisted circulation has been suggested as treatment in such cases. In order to compare the various techniques of assisted circulation, it is desirable to create experimental heart failure in animals. Ideally, the failure should be comparable to that developing clinically following a myocardial infarct. Previous studies have indicated that this is difficult to duplicate in experimental animals.3-11As early as 1862, Panum12 produced myocardial damage by injecting crude suspensions of oil, tallow, and lamp black into the root of the aorta in dogs. Samuelson,13 in 1881, produced a myocardial infarct by ligating the anterior descending branch of the left coronary artery. The same year Conheim and Von Schulthess-Rechberg14 noted that such ligations rarely produced significant hemodynamic changes unless associated

WITH THE development of low-priming volume oxygenators, assisted circulation has become available for emergency use. It has been suggested as treatment for a number of conditions including septicemic shock,1 cardiac arrest,2,3 pulmonary insufficiency,4 and congestive heart failure.5-12 Of these, emphasis has been placed on the use of circulatory support for the treatment of intractable heart failure after a myocardial infarction. The results, however, have been inconsistent and further evaluation of the use of assisted circulation in the treatment of heart failure is indicated.In a previous publication,13 a technique was described for the production of experimental heart failure in animals by multiple coronary ligations. The resulting failure was found to be comparable to that occurring clinically following a myocardial infarction. The purpose of this study is to evaluate the effectiveness of various methods of assisted circulation in the treatment of experimental heart failure. METHODS Heart

The sinus venosus type of atrial septal defect is a common lesion located in the upper portion of the septum which is characteristically associated with anomalous drainage of pulmonary veins. Hemodynamic effects resemble those of any atrial defect located in the septum secundum or upper portion of the septum. Surgical repair of the lesion should be done utilizing temporary cardiopulmonary bypass, and recognition by the surgeon of the technical problem is important. Closure of the septal defect and transposing the anomalous pulmonary veins usually necessitates use of a patch prosthesis for complete repair without producing stenosis of the veins.

The technique of cardiopulmonary bypass must frequently be altered to adjust to the specific needs of the patient. Several interesting conditions have recently been encountered in which it seemed desirable to maintain dual inflow perfusion utilizing 2 separate arterial cannulae, 1 supplying the upper and another the lower portions of the body. This technique is especially useful in those cases having an impedance to blood flow through the thoracic aorta. Although somewhat unusual, such problems are occasionally encountered as characterized by the patient with a Hufnagel valve in the descending aorta. In this instance the femoral artery alone would not be a suitable inflow site, inasmuch as blood could not pass through the valve in a reverse direction. Although the bypass could be accomplished through the left subclavian artery, this vessel may be too small to accommodate high flows. The problem may be easily resolved by using 2 inflow catheters,