Arthur B. Lee

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.

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.

Single-Stitch Fixation of Coronary Artery Perfusion Cannulas

Abstract A relatively simple and safe method for fixation of coronary perfusion cannulas is described and illustrated.

Fifteen Year Experience with Atrial Electrodes and Pacing

Two hundred and twelve patients were treated in our institution, since 1968, with long term atrial and atrio/ventricular sequential pacing utilizing different atrial electrodes. Indications included, I. atrial/ventricular arrythmia (16 pts.), 2. sick sinus syndrome with bradycardia (54 pts.), 3. sick sinus syndrome with brady/tachycardia (32 pts.), 4. intermittent heart block (73 pts.), 5. conversion from DVI to DDD pacing (8 pts.), 6. following open heart surgery (21 pts.), 7. miscellaneous (7 pts.). Forty-one (19%) of the 212 pts. had pre-existing congestive heart failure. Since 1968, a variety of atrial electrodes have been used; I. epicardial electrodes: a) modified (Lajos, 27 pts.), b) conventional (17 pts.), 2. transvenous electrodes; a) standard “J” (102 pts.), b) Mark I Lajos (14 pts.), and c) Mark II Lajos (52 pts.). Electrode related complications include, 7 instances of atrial dislodgement, 8 instances of pectoral muscle stimulation and 8 instances of diaphragmatic stimulation. Reprogramming was extensively employed with 64 instances of changes in rate (24), sensitivity, (8) output, (2) pulse width, (9) pulse interval (2) or modes (19). Atrial threshold characteristics were 1.53 ± 0.8911 mVolts, 3.17 ± 2.1909 mAmps, P wave 3.26 ± 2.3569 mVolts at time of implantation. Based on our experience, the evolution of modern electrode technology has provided safe and long term atrial and A-V sequential pacing. Contraindications are limited to refractory atrial flutter or fibrillation. The utilization of the single pass, double electrode combined with a multiprogrammable unit has added to our armamentarium, a new method of treating patients when pacing is required.

Influence of length of aortic occlusion with cold potassium cardioplegia on early and late mortality in cardiac valve replacement.

This study determines if prolonged aortic crossclamp time (ACC) with the use of cold potassium cardioplegia during elective cardiac valve replacement contributed to the risk of operative mortality in 225 patients. In Group I (143 patients), the ACC was less than 120 minutes (mean 86) and in Group II (82 patients), it was greater than 120 minutes (mean 146). The preoperative variables showed that Group II contained more severely ill patients who were undergoing more complex operations than in Group I. The operative mortality rate was 7% in Group I and 10% in Group II (p = not significant). Postoperative inotropic support was required in 13% of Group I and 30% of Group II patients (p less than 0.005). Operative mortality in patients in New York Heart Association (NYHA) functional class I and II was 0 and in patients in classes III and IV it was 13% (p less than 0.00008). Five percent of patients in NYHA classes I and II and 32% in classes III and IV required inotropic support (p less than 0.000005). The actuarial survival at 60 months was 88 +/- 3% for Group I and 77 +/- 7% for Group II (NS). For the NYHA class I and II patients, however, it was significantly better (98 +/- 2%) than class III and IV patients (75 +/- 5%) (p less than 0.0001). Analysis by logistic equation revealed that the NYHA functional classes III and IV were significant incremental risk factors for probability of in-hospital mortality (p less than 0.0001) but not the ACC time (p greater than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)