Acute effects of oral labetalol on myocardial conduction after coronary artery bypass grafting.

Cardiac electrophysiologic effects of a single oral dose of labetalol were determined in seven patients 4 to 9 days after a coronary artery bypass graft. Surface ECG and bipolar electrograms recorded from temporary pacing wires affixed to the normal right ventricle and abnormal left ventricle at the time of surgery were used to determine conduction intervals. Electrophysiologic parameters were recorded during fixed-rate atrial pacing. Sinus heart rate and blood pressure were monitored. Three patients received 100 mg and four patients received 200 mg labetalol. The drug had no significant effect on intraventricular conduction intervals or QRS duration. It did not significantly influence sinus heart rate or AV conduction time, but in two patients there was prolongation in AV conduction that may have been drug-induced. Labetalol induced a modest but significant decrease in systolic and diastolic blood pressure. In another study propranolol, unlike labetalol, had prolonged AV and intraventricular conduction in the abnormal left ventricle, but not in the normal right ventricle. The absence of these effects with labetalol may reflect lesser local anesthetic effect on intraventricular conduction and an alpha-adrenergic blocking effect that interferes with beta-blockade-induced prolongation of AV conduction.

Left ventricle to aorta valved conduit for relief of diffuse left ventricular outflow tract obstruction.

Operative relief of congenital tunnel subaortic stenosis by means of local incision or excision, or both, has generally been unsatisfactory. The use of a valve-bearing conduit between the left ventricular apex and thoracic aorta offers a predictable means of bypassing the left ventricular outflow obstruction. The procedure was used in a 17 year old girl with an excellent hemodynamic result. The history of operative management with diverting plantation of valved conduits in this position have not been defined, but use of these prostheses appears advisable in severe subvalvular, valvular and supravalvular obstructions that are not readily amenable to predictable and safe surgical palliation. The operation may prove useful in selected cases of idiopathic hypertrophic obstructive cardiomyopathy.

Reoperation, emergency and urgent open cardiac surgery in Jehovah's Witnesses.

Progressive advances in perfusion technology and perioperative supportive management have made it possible for members of the Jehovah's Witnesses religious group to undergo open cardiac operations with remarkable safety. However, hospital mortality remains high in (1) patients requiring reoperation (in whom both technical and bleeding problems tend to be more frequent) and (2) patients with significantly compromised cardiac performance requiring urgent or emergency operation. Employing a number of perioperative measures designed to minimize blood loss and maintain hematocrit levels (including use of the recently available recombinant human erythropoietin in two patients whose cases are reported herein), 13 reoperations and five urgent or emergency operations were performed. The one death in the entire series occurred in a patient (reoperation group) who died of a cerebrovascular accident of presumed embolic etiology, having undergone combined debridement of a stenotic heavily calcified aortic valve and a second coronary artery revascularization procedure. None of the patients required surgical exploration for bleeding. We suggest that currently available methodology permits Jehovah's Witnesses to undergo reoperation, emergency surgery, or urgent open cardiac operation at a level of risk not dissimilar to that seen in patients who permit use of homologous blood and products in their treatment.

Poloxamer 188 improves neurologic outcome after hypothermic circulatory arrest.

Poloxamer 188, an amphipathic copolymer with cytoprotective properties, was investigated as a means of improving neurologic outcome after a prolonged period (150 minutes) of deep hypothermic circulatory arrest. Dogs were perfusion cooled and surface cooled to 10 degrees C, the heart was arrested for 150 minutes, and then the dogs were rewarmed and weaned from bypass. Seven dogs were treated with poloxamer 188 before and after deep hypothermic circulatory arrest. Six control dogs were treated with saline. Surviving dogs were evaluated for 1 week after deep hypothermic circulatory arrest for neurologic deficits or behavioral changes. Neurologic outcome was graded by the following system: grade 1, death within the observation period; grade 2, comatose; grade 3, holds head up; grade 4, sits up; grade 5, stands; grade 6, normal in both behavior and gait. There were no deaths in the seven poloxamer 188-treated animals versus three deaths in the six control dogs. Poloxamer 188-treated dogs also manifested significantly less neurologic dysfunction after deep hypothermic circulatory arrest than did the control group (p less than 0.003). This study shows that poloxamer 188 has a significant impact in improving neurologic outcome after exceptionally long periods of deep hypothermic circulatory arrest.

Management of postcardiotomy hypertension by microcomputer-controlled administration of sodium nitroprusside.

Manual administration of sodium nitroprusside in patients who have undergone cardiac operations can be associated with wide swings in mean systemic arterial pressure. Moreover, it is necessary for constant attention to be paid in order to minimize these potentially catastrophic arterial pressure changes. A microcomputer-based controller was constructed in the belief that it might improve the accuracy of systemic arterial pressure control as well as relieve the clinical staff of a time-consuming task. Comparison was made of the effectiveness of manual control versus computer control of sodium nitroprusside infusion in two groups of patients with similar clinical characteristics. In the manual control group the mean systemic arterial pressure could be maintained within 5 mm Hg of the target pressure only half (52%) of the time. In the computer-controlled group the mean systemic arterial pressure was maintained within 5 mm Hg of the target pressure 94% of the time (p less than 0.005). Thus, computerized control of sodium nitroprusside infusion eliminated the need for an intensive care unit nurse to be "locked into" the task of making frequent adjustments of infusion rate. Of even greater importance, control of mean systemic arterial pressure was more precise.

Coronary artery spasm and perioperative cardiac arrest.

There has been increasing interest in coronary artery spasm as etiopathogenic mechanism for various syndromes associated with myocardial ischemia. A case with documented organic coronary artery disease is presented, in which coronary artery spasm was the probable cause of intraoperative and early postoperative cardiac arrest. We recommend that coronary spasm be considered in the differential diagnosis of perioperative cardiac arrest.

Open heart surgery in patients in the eighth and ninth decades of life.

One hundred fifty-one patients aged 70-89 years underwent a variety of open heart surgical procedures during a period of 1 year. We divided these patients into two groups: Group A was comprised of 127 patients between 70 and 79 years of age. In group B, 24 patients were between 80 and 89 years of age. These patients underwent elective open heart surgery. Information was retrieved retrospectively from the computerized data pool of the cardiothoracic registry in our institution. Statistical analysis in these two groups revealed no significant differences in any of the evaluated factors. We concluded that age should not be a contraindication for cardiac operations.

The use of vein allografts as sidearms for intraaortic balloon insertion.

Femoral artery cannulation for intraaortic balloon counterpulsation may be attended by difficulties due to changes in the vessel wall and the inherent stiffness of Dacron grafts. A substitute technique utilizing venous allografts is described. The advantages are enumerated and are related to allograft pliability. Fifty-nine such procedures have been done without related complications.

Administering cold cardioplegia in patients undergoing coronary artery bypass grafting.

In patients undergoing coronary artery bypass grafting (CABG), use of hypothermic cardioplegia for myocardial protection may not always achieve even cooling in the areas distal to a severely obstructed artery. Employing simultaneous myocardial temperature measurements, we documented "warm" areas in some patients having CABG. We then devised a technique of combined aortic root and intracoronary cardioplegic infusion. This has achieved prompt cooling of the warm areas and has resulted in uniform myocardial temperatures of 5 degrees to 8 degrees C.

Use of a left heart assist device after intracardiac surgery: technique and clinical experience.

A left heart assist device (LHAD) has been employed in 14 patients. All had advanced heart disease and were in low cardiac output after repair, such that they could not be separated from cardiopulmonary bypass despite prolonged support and adjuvant therapy, including drugs, pacing, and use of intraaortic balloon counterpulsation whenever possible. Apart from special cannulas, the equipment necessary for the LHAD is widely available. An asset of the system (left atrial-ascending aorta bypass of the left ventricle) is that it may be terminated without reentering the thorax to remove the cannulas. This is accomplished with precisely fitting obturators that obliterate the cannula lumens and allow the tubes to be permanently implanted. This concept is believed important since critically ill patients requiring support are precisely those in whom added risk would be imposed by a second operation. Of the 14 patients who have had intraoperative and postoperative support (up to 6.8 days), 9 were weaned from the device and 6 were dismissed from the hospital. Four patients remain alive and are improved, the longest at 22 months since operation. The favorable performance of the LHAD suggests that it may prove useful either when intraaortic balloon counterpulsation cannot be successfully deployed or when it has failed to achieve hemodynamic stability.

Long-term study of the ultrastructural changes of myocardium in patients undergoing cardiac surgery, with more than 10 years follow-up.

The myocardium from 44 patients undergoing open cardiac surgery was studied to determine if alterations demonstrable with the electron microscope could be related to prognosis. Planimetric methods were used to evaluate myofibrils, Golgi, mitochondria, myelin figures, other organelles, and intracellular space in order to achieve as objective a measurement as possible. Morphologic changes were graded and correlated with clinical findings and results after long-term follow-up. Factors evaluated in terms of survival included patient age, degree and extent of valvular disease, the presence of coronary artery disease, and degenerative changes of the myocardium as demonstrated ultrastructurally. Patients dying, of cardiac causes, within the first 5 years, had a higher ultrastructural grade than those surviving for more than 10 years. Statistical analysis, using stepwise regression methods, demonstrated a highly significant correlation (P less than 0.001) between cardiac ultrastructural integrity and prognosis. The addition of age to the prediction model was also significant (P less than 0.04), using the two variable models, EM grade and age were, similarly, highly significant (P less than 0.001).

Use of nonblood priming for open-heart surgery in dogs.

Three electrolyte solutions were used as priming perfusates for 1 hour of cardiopulmonary bypass in 9 dogs. Arterial blood pressure was maintained at a satisfactory level during perfusion and returned to the original ranges shortly after bypass. Measurement of various blood constituents indicated that they were constantly maintained in the normal range during the procedure. The PVC decreased sharply until the 3rd postperfusion day, then returned to the base-line values. Similar patterns were obtained for each solution, with no additional infusion being administered after bypass. All dogs recovered without complications and evidence of cerebral abnormalities was not seen. The dogs were euthanatized and necropsied 14 days after surgery and all major organs appeared normal on gross examination.

Nine-month evaluation of dogs after open-heart surgical removal of heartworms.

Adult heartworms were surgically removed from 4 infected dogs by use of intracardiac techniques during cardiopulmonary bypass. The number of worms removed ranged from 12 to 14 per dog. Observation for 9 months after surgery gave no clinical evidence of active adult heartworm infection, in spite of the consistent finding of circulating microfilariae during the follow-up period. There were no significant early or late postoperative complications. Results of postoperative hematologic and biochemical studies were unremarkable. At necropsy (following euthanasia, 9 months after surgery) the heart and pulmonary arteries of all dogs were free of adult heartworms; pathologic changes attributable to residual infection were not found.

Role of the Hancock "stabilized glutaraldehyde process" bioprosthesis in the management of mitral valve disease.

The low mortality of isolated mitral valve (MV) replacement permits attention to be focused on those valve-related factors which affect the quality of life after operation. Comparison of a number of MV prostheses indicates that all perform satisfactorily from the hemodynamic standpoint. An asset of the "stabilized glutaraldehyde process" (SGP) Hancock bioprosthesis (H-B) is the significantly lower incidence of thromboembolism encountered in patients who have not been permanently anticoagulated. While additional time is required before meaningful durability comparisons can be made, the absence of valve failure and the low incidence of tissue dysfunction in H-B over 6 1/2 years is encouraging. Although the ideal device for replacing the MV is not yet available, the Hancock SGP bioprostheses represent the best compromise of available choices.

Temporary mechanical support of left ventricular failure following open heart surgery.

Patients coming to open heart surgery with advanced cardiac dysfunction may require mechanical cardiac support to avoid life-threatening low cardiac output in the postoperative period. 15 patients who could not be withdrawn from cardiopulmonary bypass because of low cardiac output were supported with a left heart bypass system (left atrium to ascending aorta). Ten were ultimately separated from the device, 6 were dismissed from the hospital and 4 remain well (the longest 2.6 years postoperative). A major asset of the device is that thoracic reentry is not required when support is discontinued.