Late ventricular fibrillation following successful resuscitation from postinfarction cardiogenic shock with intraaortic balloon pumping.

Early ventricular fibrillation occurs in approximately 5% of patients admitted for acute myocardial infarction. Although late ventricular fibrillation (> 48 hours postinfarction) may occur in stable patients, it occurs more commonly when severe left ventricular power failure is present. We have encountered late ventricular fibrillation in three of 42 (7%) patients treated with intraaortic balloon pumping (IABP) for profound cardiogenic shock secondary to myocardial infarction. These patients progressed to our hemodynamic Class A prior to weaning, and were thought to be stable prior to IABP removal. They were the only ones who expired after achieving Class A status. The episodes of late ventricular fibrillation occurred after the patients had been successfully weaned from IABP and were free of arrhythmias. This experience suggests that prolonged antiarrhythmic therapy may be indicated for postinfarction patients who have had ventricular dysrhythmias during IABP support.

MACROSCOPIC, MICROSCOPIC, AND MECHANICAL ANALYSES OF PROTOTYPE DOUBLE VELOUR VASCULAR GRAFTS.

In-vivo and ex-vivo evaluations of two prototype double velour tube grafts have been conducted. The experimental grafts were fabricated from terry cloth derivatives of the Dacron polyester material that is used in the construction of presently available Microvel(R) Double Velour and Cooley Double Velour Guideline(R) grafts.(*) The use of terry cloth derivatives in the experimental grafts provides a velour pile that is more uniform in height and density than current clinical grafts. The hypothesis examined by these studies was whether the utilization of terry cloth derivatives provides a more perfect capsular and luminal surface for fibrous tissue attachment and ingrowth, thereby enhancing neointimal formation at the blood contacting surface. Using standard techniques, prototype grafts were implanted in the abdominal aortas of dogs for test periods of 1 to 6 months. All grafts remained patent throughout the healing period. At explantation, the macroscopic and microscopic properties of the grafts were examined and characterized. Neointimal analysis demonstrated that the lighter denier, higher porosity prototype consistently produced more homogeneous blood-contacting surfaces with smoother contours and more complete endothelialization than the heavier denier, lower porosity prototype. From these analyses, we can conclude that both prototype grafts possess the basic properties of useful arterial prostheses. They are not prone to early thrombosis, and exhibit rapid healing properties. This study indicates that the use of terry cloth derivatives provides a more uniform, less random velour pile and that arterial grafts constructed from such materials produce more uniform and biologically stable neointimas.

PREFABRICATION DESIGN CONSIDERATIONS FOR A LONG-TERM ELECTRICALLY-ACTUATED ABDOMINAL LEFT VENTRICULAR ASSIST DEVICE (E-TYPE ALVAD).

The conceptual design and development of a long-term, low-profile intracorporeal left ventricular assist device is a multifaceted project involving a series of technical, anatomic and physiologic considerations. Patients with severe left ventricular failure refractory to all other forms of therapy could benefit from such a device. Prior to fabrication of such a blood pump, consideration must be given to physiologic parameters of the projected patient population. The pump must be designed to meet physiologic demands and yet conform to the anatomic constraints posed by the patient population. We measured the body surface area (BSA) of a group of patients (n=50) and found the mean BSA for this group to be 1.804 +/- 0.161 m(2). Using 25 ml/m(2) as a stroke volume index indicative of left ventricular failure and a stroke volume index of 45 ml/m(2) as normal, distributions of stroke volumes (normal and in left ventricular failure) were plotted for a potential population and demonstrated that 63% of the projected population can be returned to normal by a pump with a stroke volume >/= 83 ml. Cadaver fitting studies established that 73% of the potential population can accommodate an ALVAD 10.8 cm in diameter. In-vitro tests demonstrated that a pump stroke volume >/= 83 ml could be achieved by the proposed pump with a 15 mmHg filling pressure at rates up to 125 B/min. A pusher-plate stroke of 0.56 inches would be necessary to provide a stroke volume >/= 83 ml. The percent of the patient population that could be served was determined by excluding those in whom the pump would not fit or in whom it would provide less than a normal resting stroke volume. Approximately 73% of the projected patient population would accommodate this pump and be returned to normal circulatory dynamics.

SUCCESSFUL AORTOCORONARY BYPASS SURGERY IN A PATIENT WITH CLASSICAL HEMOPHILIA A.

A patient with documented Factor VIII deficiency (classical Hemophilia A) and a history of previous severe intra- and postoperative hemorrhage and transfusion reaction underwent myocardial revascularization for advanced triple vessel coronary artery occlusive disease. The coagulation status was investigated, and a replacement regimen was instituted. The surgical procedure and postoperative course were uneventful.

UTILIZATION OF HAND-HELD PROGRAMMABLE CALCULATORS FOR RAPID BEDSIDE COMPUTATION OF PHYSIOLOGIC-PHARMACOLOGIC VARIABLES AND PROGNOSTIC INDICES DURING MECHANICAL CIRCULATORY SUPPORT.

This study describes five programs that may be used on compact, low-cost programmable calculators with adequate memory and sufficient numbers of program steps to compute cardiorespiratory variables. These short programs are especially useful in the operating room and at the bedside.