Myocardial reinfarction after anesthesia and surgery

During the years 1974 and 1975 at our institution, 587 patients who had suffered previous myocardial infarctions underwent anesthesia and surgery. Thirty-six (6.1%) had a reinfarction and 25 (69%) died. Patients operated on within three months of the previous infarction had a 27% reinfarction rate. This decreased to 11% if the infarct had occurred three to six months previously and stabilized at 4% to 5% if the interval was more than six months. Risk factors associated with significantly increased reinfarction rates included preoperative hypertension, intraoperative hypotensive episodes, and noncardiac thoracic or upper abdominal operations of more than three hours' duration. Time under anesthesia was strikingly correlated with reinfarction rates in the entire group. Postoperative intensive care unit admission did not significantly affect the reinfarction rate, nor did diabetes, angina, patient age or sex, or site of the previous myocardial infarction.

Discontinuing anticoagulant therapy in surgical patients with cardiac valve prostheses. Observations in 180 operations

Between 1962 and 1975, a total of 159 patients with previously implanted man-made cardiac valve prostheses underwent 180 subsequent noncardiac operations at Mayo Clinic. All of these patients were receiving anticoagulants. The overall incidence of their documentable thromboembolic complications was approximately 10%. None of the postoperative complications occurred while the patient was in hospital, with the earliest such complication seen two years later. Patients receiving anticoagulants on a long-term basis did, however, have a 13% incidence of various difficulties with hemostasis during and following the later operations. We conclude that there is minimal risk to patients with cardiac valve prostheses who are receiving anticoagulants when the drug regimen is stopped for one to three days preoperatively and one to seven days postoperatively.

Efficacy of dopamine, dobutamine, and epinephrine during emergence from cardiopulmonary bypass in man

Hemodynamic effects of dobutamine and dopamine (both 5, 10, 15 microgram/kg/min) and epinephrine (0.04 microgram/kg/min) were studied immediately following cessation of cardiopulmonary bypass in 34 patients with preoperative evidence of left ventricular dysfunction. Significant increases in mean cardiac index were seen with dobutamine (15, 25, and 26% respectively), and epinephrine (30%). The largest increases occurred with dopamine (44, 53, and 64 percent respectively). Responses varied from patient to patient, however. Seven patients developed marked output increases without concomitant increases in arterial pressure, whereas seven others showed "satisfying" increases in arterial pressure without appreciable output increases. Heart rate increases were small and few arrhythmias were noted. We conclude that dopamine, epinephrine, and dobutamine all are effective inotropic agents during the immediate post-bypass period, with variations discussed in detail. None possess the disturbing chronotropic and arrhythmogenic effects of isoproterenol (previously studied). Efficacy of administration of inotropic drugs seems best assessed by serial output measurements during this period.

Myocardial infarction after general anesthesia

During 1967 and 1968, a total of 32,877 patients had general anesthesia at the Mayo Clinic; 422 had previous myocardial infarction. Of these 6.6% experienced another infarction during the first postoperative week. There was no relationship between incidence of postoperative reinfarction and type or duration of anesthesia. However, operations on the thorax and upper abdomen were followed by three times as many reinfarctions as operations at other sites. Patients who were operated on within three months of infarction had a 37% reinfarction rate. This rate decreased to 16% in patients at three to six months after infarction, and remained at 4% to 5% when infarction had occurred more than six months previously. A significantly higher number of myocardial infarctions occurred during the third postoperative day.

Anesthesia and postoperative care for cardiac operations

Almost three decades have passed since the establishment of open-heart surgery, and in such a short life span the specialty has established itself scientifically and reached a certain maturity. New techniques, better understanding of the pathophysiology of cardiac problems, and the effective use of new drugs constantly improve the results of operation. Greater experience in anesthetic management and improved postoperative care will contribute much to the success of this youngest surgical specialty. This review outlines the current principles of anesthesia and postoperative care of patients undergoing cardiac operations. Preanesthetic evaluation provides guidance for anesthetic management, supportive techniques, and postoperative care. During operations, light anesthesia is usually sufficient for patients with cardiac disease and minimizes myocardial depression. Monitoring must provide data on the physiological changes that are taking place from moment to moment during and after operations. Perfusion produces a highly abnormal state, and the severity of complications varies with its duration. Introduction of new drugs has also facilitated hemodynamic management during and after operations. Postoperative care is based on careful observation of the patient and early detection of trends, both of which lead to preventive rather than curative treatment wheneven possible.

Dobutamine for inotropic support during emergence from cardiopulmonary bypass

Dobutamine, a recently introduced derivative of dopamine, is reported to retain inotropic properties with less pronounced chronotropic and arrhythmogenic effects than isoproterenol. The drug was evaluated in two doses, 5 mug/kg/min and 10 mug/kg/min, in two groups of ten patients each, during emergence from cardiopulmonary bypass. A third group of five patients was studied similarly with isoproterenol, 0.02 mug/kg/min. Cardiac index increased 16 and 28 per cent eith the two doses of dobutamine, respectively, and 9 per cent with isoproterenol. Heart rate, in contrast, increased 6 and 15 per cent with dobutamine (not significant) and 44 per cent with isoproterenol (significant). Dobutamine seemed to associated with fewer arrhythmias than isoproterenol. It is concluded that dobutamine, 5-10 mug/kg/min, is suitable for use during emergence from cardiopulmonary bypass and may possess advantages over isoproterenol.

Hemodynamic effects of morphine during and early after cardiac operations

Hemodynamics and blood gases were measured before and 15 minutes after small (10 mg/70 kg) doses of intravenously administered morphine in two groups of patients having open heart surgery. In one group, the study was undertaken after median sternotomy but before perfusion. The other group had been in the intensive care unit for approximately 1 hour. No changes were found in either group in cardiac index, atrial pressures, arterial pressure, or blood gas variables. However, mean systemic vascular resistance decreased from 41.5 to 35.4 after morphine was given postoperatively. Hence, hemodynamically, morphine is a safe drug if given in small doses for pain relief and sedation early after open heart surgery.

Hemodynamic effects of isoflurane and halothane in patients with coronary artery disease

In 12 patients undergoing saphenous vein coronary artery bypass operations, cardiovascular hemodynamics were studied in the awake state (control) and during anesthesia with isoflurane (inspired concentration, 1.24%, 7 patients) or with halothane (inspired concentration, 0.77%, 5 patients). Isoflurane anesthesia was accompanied by decreases of 19% in the cardiac index (Q), 19% in mean arterial pressure (AP), and 16% in heart rate (HR). Only the change in AP was statistically significant. Halothane anesthesia was accompanied by decreases in Q (28%), AP (22%), and HR (10%). The changes in Q and AP were significant. HR did not change significantly following the induction of anesthesia with either agent. The decrease in AP was similar with both agents, and, in this regard, neither agent was clearly superior for patients with occlusive coronary artery disease.

Circulatory effects of vagal inflation reflex in man

In five patients studied during cardiopulmonary bypass, lung inflation had no effect on heart rate or on total peripheral resistance. Changes of heart rate could be induced my manipulation of the right or left atrium.

Failure of transfusion of autologous whole blood to reduce banked-blood requirements in open-heart surgical patients

Although transfusion of autologous blood by the method described would seem to be a safe and proctical means of reducing banked-blood requirements for open-heart operations, our experience indicates that the amount of blood needed to be added to the pump oxygenator more than negates the value in reducing intraoperative blood requirements. In fact, autologously transfused patients used more blood than did control subjects. Platelet and fresh-frozen plasma administration was not significantly different for the autologous transfusion or control group.