George Schimert

Left Thoracotomy Reoperation for Coronary Artery Disease

Abstract Twenty patients underwent reoperative coronary artery bypass grafting (CABG) through a left thoracotomy since 1971. This was their second CABG in 16 patients, third in three patients and fourth in one patient. Surgery was performed from 1 to 16 years following the initial procedure. Demographic data showed no significant variation from patients undergoing standard reoperative CAGB in this institution. Ejection fraction varied between 30% and 73%. Cardiopulmonary bypass technic has gradually developed since 1971, using the left femoral artery and vein. For venous cannulation a 50‐cm long catheter was positioned in the right atrium. Monitoring included pulmonary artery catheter with oximetry. Fibrillatory arrest of the heart was utilized with 18–33°C core cooling cardioplegia. The left internal mammary artery (6) and reverse saphenous veins (44) were used for an average of 2.5 grafts per patient. The proximal anastomosis was placed on the descending thoracic aorta or the left subclavian artery. There were two early and no late deaths. Sixteen patients were restudied before discharge from the hospital with an early graft patency rate of 98% (41/42). The left thoracotomy approach may be preferable in selected cases of redo CABG. The danger of damage to the heart and patent grafts is greatly reduced.

Detection of creatine kinase BB isoenzyme in sera of patients undergoing aortocoronary bypass surgery

Creatine kinase BB isoenzyme (CK-BB) was detected intraoperatively in 22 of 25 patients undergoing aortocoronary bypass surgery, both in the coronary sinus and in the mixed venous blood. In a group of 10 patients in whom selective intracavitary profound hypothermic arrest was used, CK-BB values were lower than in another group of 10 patients, in whom controlled ventricular fibrillation with moderate total body hypothermia was instituted. This latter group also had higher levels of CK-MB. Patients who developed acute myocardial infarction immediately prior to or during the surgical intervention had the highest CK-BB values. This enzyme appeared as early as 15 minutes after the institution of cardiopulmonary bypass and disappeared within 6 hours. It is considered that part of the BB isoenzyme in serum of patients undergoing heart surgery is of myocardial origin.

Cold Blood-Potassium Cardioplegia

A technique is described for providing myocardial protection utilizing oxygenated blood that is drawn from the pump oxygenator and passed through two disposable cardioplegic cooling coils, which are joined in series and submerged in ice slush. A potassium-containing cardioplegic solution is run into the oxygenated blood at the level of the cooling coils. The amount of blood used in the blood-potassium cardioplegic mixture is controlled using a screw clamp. This method has been used with excellent results in 150 consecutive patients undergoing aortocoronary saphenous vein bypass grafting.

Comparison of myocardial preservation techniques for aortocoronary bypass surgery

Abstract The myocardial properties of three different techniques for cardiac arrest during aortocoronary bypass surgery were analyzed. Ventricular fibrillation and moderate total body hypothermia (30–33°C) (Group I) was found to be an insecure method of preservation. It produced a high incidence of focal irreversible ultrastructural changes (7 of 10 patients), high post-bypass CK-MB levels (mean 85.54 U/liter) indicative of myocardial damage, and impaired clinical and physiologic recovery courses. Six out of ten patients needed inotropic support, three had prolonged stay in ICU, and three patients showed Type III (unacceptable) recovery trajectories, one of whom died of myocardial decompensation four weeks after surgery. This method, which was the most common one used in our institution, was completely abandoned as a result of these studies. Potassium induced cardioplegia combined with methylprednisolone sodium succinate, hypertonic glucose and intermittent moderate topical cooling (25–27°C) of the heart (Group III) offered a generally acceptable form of myocardial protection, as only one patient showed irreversible ultrastructural changes. The mean post-bypass CK-MB level was only moderately elevated (mean 22.32 U/liter), but seven of ten patients needed inotropic support. There were no Type III recovery trajectories and two patients showed an optimal Type I recovery. Only one patient had a prolonged stay in ICU, and another patient exhibited electrocardiographic evidence of a perioperative myocardial injury pattern. Selective intracavitary profound hypothermic arrest (15–18°C) (SIPHA) offered the best myocardial protection as evidenced by remarkably well preserved ultrastructure and significantly (P These data also suggest that the major determinant of a successful myocardial preservation is the level of myocardial layer temperature, being best at the lowest temperature (15–18°C), worst at the highest temperature (30–33°C) and intermediate at 25–27°C. Additional injury may also be induced by ventricular fibrillation which by itself increases myocardial metabolic demands.

Improved Cardiovascular Hemodynamics with Atrioventricular Sequential Pacing Compared with Ventricular Demand Pacing

To determine the advantages of atrioventricular (AV) sequential pacing over ventricular demand pacing, paired cardiovascular hemodynamic studies were performed in each pacing mode at a constant heart rate. The paired studies included determination of ejection fraction (EF) by echocardiography and gated blood pool radionuclide scanning, and of cardiac output (CO) by the indicator-dilution method. There was no significant difference in EF with either pacing mode. Determined by echocardiography, EF with AV sequential pacing was 57% compared with 56% with ventricular demand pacing; by the gated blood pool method, EF with AV sequential pacing was 58% compared with 57% in the ventricular mode. Significant improvement with AV sequential pacing was seen in CO (4.75 L/min from 3.75 L/min; p less than 0.01); stroke volume (58 ml from 48 ml; p less than 0.02); arteriovenous oxygen content difference (4.9 vol% from 5.6 vol%; p less than 0.01); total peripheral resistance (1,724 dynes sec cm-5 from 2,025 dynes sec cm-5; p less than 0.01); and cardiac contractility, as reflected by mixing time (6.9 seconds from 8.0 seconds; p less than 0.02). No significant changes were noted in mean arterial or atrial pressure or in systemic oxygen consumption. In a second group of 6 patients, similar paired studies were done in AV sequential pacing modes before and after therapeutic reduction of total peripheral resistance. A significant increase in CO (43%) was observed following reduction in total peripheral resistance. We conclude that AV sequential pacing improves CO more effectively than ventricular demand pacing. Cardiac output can be further enhanced in patients with congestive heart failure by pretreatment with agents to reduce total peripheral resistance.

Decompression of the Heart with Siphon Drainage

A simple technique for inducing intracavitary hypothermic cardioplegia and decompressing the left heart through the ascending aorta is presented. The technique is based on siphon drainage, which eliminates the dangers of air embolism.

Treatment of fibrinolytic hemorrhage with proteinase inhibitors: a preliminary report.

TABLE 1 shows the antifibrinolytic agents studied and the distribution of patients treated. In early experiments,2 we have investigated antiplasmin preparations isolated from human and bovine blood and the lima bean inhibitor. When epsilon-aminocaproic acid (EACA) and TrasylolB became available for clinical investigation, we concentrated our efforts on these agents. Of 151 patients treated, 80 received EACA and 57 Trasylol. In the series where conventionally treated controls were included in the study, 75 patients were entered. EACA was obtained from the Lederle C0.t and Trasylol from the Metachem C0.S Methods employed to estimate members of the fibrinolysin system have been reported previou~ly.~.~

The use of steroids as a potentiator of hypothermic myocardial preservation in man.

Profound hypothermic preservation (15–18°C) of the arrested myocardium offers the best protection against ischemic changes and potassium cardioplegia potentiates this preservation by allowing a more dynamic postbypass recovery, but at the cost of increased intra- and extracellular edema and mitochondrial injury. This study assesses the protective value of a steroid in the perfusion solution, methylprednisolone sodium succinate (1 g/liter), in the presence of profound hypothermic (myocardial T < 20°C) potassium (K = 26 meq/liter) cardioplegia. In a randomized prospective blinded study two groups (control A and steroid B) of 10 patients undergoing a minimum of three coronary bypass grafts were compared by clinical, cardiodynamic, electron microscopic biopsy, and mixed venous lactate and creatine phosphokinase (CK-MB) isoenzyme studies. The mean anoxic arrest time and number of grafts per patient were comparable. Although the CK-MB isoenzyme levels were lower in the postoperative period in the Solu-Medrol group, this was not statistically significant. The clinical course of the two groups was similar, however the control group of patients required a far greater degree and duration of inotropic support to attain comparable recovery trajectories to the Solumedrol group of patients. Critical ultrastructural differences in the steroid-treated group were better mitochondrial preservation, increased perimitochondrial glycogen stores, and a reduction in intracellular edema. These results suggest that steroids may enhance stabilization of cellular metabolic processes under conditions of hypothermic potassium cardioplegia.

Early and Long-Term Effects of Direct Myocardial Revascularization on Cardiac Function: A Prospective Study Using Multivariable Physiological Analysis

Perioperative and late follow-up hemodynamic cardiovascular studies to assess the effects of direct myocardial revascularization on cardiac function objectively have been completed on 51 patients. Analysis of the data delineated three distinct groups basedon the patterns of their early postoperative recovery. Group I patients (12) had a hyperdynamic cardiovascular response to operation and returned to a normal physiological range of cardiac function within 24 hours. Group II patients (24) initially had moderate to severe myocardial decompensation postoperatively but responded to inotropic support and moved into the normal physiological range within 24 to 48 hours. Group III patients (15) had severe, prolonged myocardial decompensation with little response to inotropic support. There were no early deaths in Group I, 1 early iatrogenic death in Group II, and 2 deaths from sepsis, 1 in Group I and 1 in Group II. All 7 cardiogenic deaths occurred in Group III patients. Late follow-up studies 4 to 23 months postoperatively have been completed on 29 patients. These showed cardiovascular stability in the mean values in Groups I and II. Significant improvement in mean cardiac function was seen in surviving Group III patients.

Selective Intracavitary and Coronary Profound Hypothermic Cardioplegia for Myocardial Preservation: A New Technique

A technique is described for selective intracavitary and coronary hypothermic perfusion during cardiac bypass with cardioplegia to facilitate cardiac operations. A cold perfusate (Plasmalyte 148 and mannitol, 12.5 gm/L at 8 degrees to 10 degrees C) is administered with the aid of a low-flow perfusion pump into the left ventricular cavity and coronary circulation through an apical perfusion-venting (Per-Vent) catheter. This perfusate cools the myocardium rapidly and homogeneously to a temperature of 15 degrees to 20 degrees C. Within this temperature range, complete cardioplegia occurs and the safe ischemia period can be extended to 120 minutes. This method was applied in 50 unselected consecutive adult patients undergoing aortocoronary saphenous vein bypass grafting or aortic or mitral valve replacement. All patients survived and had excellent recovery of ventricular function.