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Percutaneous insertion of myocardial electrodes and electrical pacing were employed in the treatment of ten patients with A-V block complicating myocardial infarcts. The technique of wire insertion is given and representatives cases are described. Prognosis in such cases is dependent primarily on the extent of cardiac damage produced by the infarction, but electrical pacing will complement the usual therapeutic regimen.

The morphogenesis of pulmonary vascular lesions produced by autogenous clot embolism has been studied for comparison with lesions produced by hyperkinetic pulmonary hypertension. Embolic lesions differ from those produced by hyperkinetic hypertension. The embolic lesion is an eccentric fibrous plaque that protrudes into the lumen of the vessel and replaces in large part the vascular media beneath it.

Hyperkinetic pulmonary hypertension has been produced in dogs with an aorta-left pulmonary artery anastomosis. The pulmonary artery proximal to the shunt was banded so as to restrict the increased pressure to a segment of the pulmonary vasculature. Pulmonary hypertension was observed when the shunt was directed into the entire left lung of the dog, but no vascular lesions were demonstrated after as long a period of time as 93 weeks. Pulmonary hypertension and arterial lesions were found when the shunt was directed into the left lower lobe of the lung. Study of the lesions produced by this form of hyperkinetic pulmonary hypertension revealed them to be quite different in appearance and morphogenesis from lesions produced by autogenous clot embolism. The reversibility of arterial lesions was studied by restoring normal pressure in the left lower lobe. Vascular lesions characterized by medial hypertrophy of muscular arteries, muscular arterioles, and minimal to moderate degree of intimal thickening were observed to resolve. Marked intimal thickening and plexiform lesions did not resolve when followed for as long as 37 weeks.

Atrioventricular conduction blocks were produced in dogs, and ventricular stimulation was accomplished by the use of electrodes implanted either into normal myocardium or scar tissue on the myocardium. Stimulation through scar tissue requires several times the power necessary for stimulation through normal myocardium, but both are well within the limit of standard, commercially available, transistorized pacemakers. Failure of stimulation of the ventricle was not due to excessive scarring. Failure of stimulation was in every instance due to wire breakage or actual loss of contact between the wire and the myocardium.

Cardiac tamponade was diagnosed in 197 patients admitted over 20 years (1955-1974) to the Charity Hospital of New Orleans, for emergency treatment of pentrating mediastinal injuries. Of the 197, 174 definitively treated patients followed one of three patterns of management: 96 had OR thoracotomy, 68% were unstable, and preoperative pericardiocentesis reduced mortality from 25 to 11% (p less than 0.01); 44 had emergency thoracotomy, 91% were unstable, and prethoractomy pericardiocentesis decreased mortality from 94 to 63% (p less than 0.05); 34 patients primarily with isolated stab wounds, were treated nonsurgically with pericardiocentesis and observation, only 50% were unstable and there was 15% mortality. Recurrent tamponade did not significantly increase overall or operative mortality in patients with pericardiocentesis.early, even presumptive, diagnosis of tamponade; immediate pericardial decompression via pericardiocentesis; and rapid transfer to OR for thoracotomy or sternotomy and cardiorrhaphy with continous pericardial decompression via intrapericardial catheter.

The technic of banding the pulmonary artery is described. Twenty infants with intractable cardiac failure secondary to interventricular septal defects have had banding with one operative and one late death. The operation is palliative, and definitive surgery probably must be done when the child is 3 to 5 years of age. Banding the pulmonary artery is a relatively safe procedure but the mortality of banding plus ventricular closure and unbanding remains to be evaluated.

ONE OF THE therapeutically reversible acute complications of recent myocardial infarction is the development of complete heart block. When the heart rate falls below 25 to 30 beats per minute, syncopal or convulsive seizures develop accompanied by the clinical picture of shock. This emergency requires immediate therapy not only for survival, but to prevent cerebral, cardiac, and renal complications resulting from repeated episodes of inadequate circulation. In the above situation we have employed a procedure similar to that described by Dr. C. W. Lillehei 1 for therapy of heart block complicating surgical repair of ventricular septal defects. The procedure consists of inserting a No. 18 spinal needle into the right ventricular cavity by puncturing the chest wall just medial to the point of maximal impulse and directing the needle superiorly and medially toward the second right costochondral junction. Then a No. 26 stainless steel wire is passed through the needle