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Intermittent ischemia: an alternative to cardioplegic arrest during myocardial revascularization surgery
| Content Provider | Semantic Scholar |
|---|---|
| Author | Galbraith, G. D. Gassmann, C. J. |
| Copyright Year | 1986 |
| Abstract | Cardioplegic myocardial protection has become the standard for myocardial revascularization surgery (MRS). In contrast, our group performed 500 consecutive MRS' with intermittent aortic cross-clamping for distal anastomoses, left ventricular venting, and systemic hypothermia. Average patient age was 62 years (range: 30-89 years). 194 patients (38.8%) had urgent or emergent MRS. 251 patients (50.2%) had unstable angina and 123 others (24.6%) had preinfarction angina (rest pain in the hospital); 27 (5.4%) had evolving myocardial infarctions (MI). 174 patients (34.8%) had ejection fractions (EF) <0.50 including 75 patients (15.0%) with EFs <0.40; 16 patients (3.2%) had left ventricular aneurysms. Average number of grafts was 3.3 per patient and average ischemic time was 7.6 minutes per graft. There were five hospital deaths (1.0% ), none due to poor myocardial protection and low cardiac output. Only three survivors (0.6%) required an intra-aortic balloon pump (IABP) to wean from cardiopulmonary bypass (CPB): two had acute Mls preoperatively; the other had EF <0.30 and intractable atrial arrhythmias. Only two other patients (0.4%) received any inotropic infusions postoperatively. 18 patients (3.6%) had perioperative Mls. These results, particularly the virtual absence of postoperative inotropic support, in unselected patients of whom 80% had acute coronary syndromes, indicate that intermittent ischemia (II) can provide excellent myocardial protection for MRS. Brief periods of II alleviate concerns about cardioplegic protection via occluded coronary arteries or internal mammary artery grafts. II provides a simple and safe alternative to cardioplegic arrest for myocardial protection during MRS. Direct communications to: George D. Galbraith, B.S., C.C.P., Division of Cardiothoracic Surgery, Lancaster General Hospital, 555 North Duke Street, P.O. Box 3555, Lancaster, PA 17603 106 Introduction ______________ _ Profoundly hypothermic, hyperkalemic cardioplegic arrest of the heart has become the standard technique for myocardial protection during myocardial revascularization surgery (MRS). Since cardioplegia is utilized by virtually all cardiac surgical teams in the United States, the vast majority of perfusionists trained since the mid-1970s (when cardioplegia was successfully reintroduced into cardiac surgical practice) have never been exposed to other non-cardioplegic techniques of myocardial protection. It is the purpose of this paper to present to the perfusion community the physiological bases and specialized techniques of intermittent ischemia as an alternative to cardioplegic arrest during MRS. Cardioplegia is not the myocardial protection panacea of modern cardiac surgery. Randomized and non-randomized studies comparing cardioplegic with non-cardioplegic techniques have not demonstrated differences in clinical results. 14 Our rationale for using non-cardioplegic myocardial protection during myocardial revascularization surgery has three bases. First, it provides satisfactory clinical results even in patients with severe left ventricular dysfunction. Second, when executed properly a non-carrdioplegic scheme is more versatile and allows the cardiac surgical team greater intraoperative flexibility. Third, we are concerned that cardioplegic myocardial protection is inherently ill-suited for patients with multiple occluded native coronary arteries, patent internal mammary artery grafts, or abundant noncoronary collateral blood supply. Patient Population 500 consecutive patients underwent primary MRS at Lancaster General Hospital with intermittent ischemia from September 7, 1983, to AprilS, 1985. All patients in this series were operated upon by two cardiac surgeons experienced in the technique of intermittent ischemia. Seven patients who underwent MRS during this time period were excluded from analysis because they had atherosclerotic aortic disease which precluded safe application of an aortic partial occlusion clamp for proximal vein graft anastomoses. MRS in six of these seven patients was therefore performed with a crystalloid cardioplegic technique of myocardial protection for proximal and distal anastomoses during a single prolonged period of aortic cross-clamping. The seventh patient had total calcification of the ascending aortic arch and transverse aorta, combined with bilateral femoral artery occlusion, that precluded safe cannulation for cardiopulmonary bypass. MRS was successfully performed in this patient utilizing a sequential left internal mammary artery graft to the left anterior descending and first diagonal coronary arteries with local vessel occlusion and without the aid of cardiopulmonary bypass. There were no deaths among these seven excluded patients. Patients were also excluded if they underwent concomitant valvular repair or replacement since we use cardioplegia and a topical hypothermia jacket for valve procedures. 5 No patients were excluded from this study because of poor preoperative left ventricular function, ventricular aneurysm, emergency operation, etc. The clinical characteristics of the 500 patients studies are listed in Table 1. The average age of all patients was 62 years, with a range of 30 to 89.9 years. 106 patients (21.2%) were 70 years old or greater. 130 patients (26.0%) were female. 94 patients (18.8%) were diabetic. Two hundred fiftyone (251) patients (50.2%) had unstable (progressive) angina, defined as angina of recent onset or angina with recent increase in frequency or severity. One hundred twenty-three (123) patients (24.6%) had preinfarction angina, defined as anginal pain at rest while in the hospital. One hundred ninety-four (194) patients (38.8%) underwent urgent or emergent operations. An urgent operation was performed when the patient's condition was determined to be too precarious to allow safe discharge from the hospital without MRS. An emergency operation was defined as any MRS performed within eight hours of cardiac catheterization. One-half of the patient population studied had suffered a preoperative myocardial infarction (MI). In 27 patients (5.4% ), the MI was evolving acutely, and in 11 others (2.2% ), an MI had occurred within the preceding seven days. Twenty-six patients (5.2%) had received streptokinase thrombolytic therapy at the onset of MI symptoms, and 35 patients (7.0%) had undergone prior percutaneous transluminal coronary angioplasty (PTCA). In 10 patients (2.0%), PTCA had been performed less than 24 hours prior to MRS. One hundred seventy-six (176) patients (35.2%) had left ventricular ejection fractions (EF) of 0.50 or less, including 100 patients (20.0%) with EF less than or equal to 0.40. Sixteen patients (3.2%) presented with ventricular aneurysms. Table 1 Preoperative Clinical Characteristics (500 Patients) Number of Patients Percent SEX Male 370 74.0 Female 130 26.0 AGE < 70 Years 394 79.8 2': 70 Years 106 21.2 ANGINA Asymptomatic 14 2.8 Stable 112 22.4 Unstable' 251 50.2 Preinfarction 123 24.6 PRIOR MYOCARDIAL INFARCTION Total Patients 248 49.8 Evolving 27 5.4 Within 1-7 Days of MR9 11 2.2 Within 1-6 Weeks of MRS 51 10.2 Remote (more than 6 weeks) 159 31.8 DIABETES MELLITUS 94 18.8 PREOPERATIVE STREPTOKINASE THERAPY 26 5.2 PREOPERATIVE PTCA Total Patients 35 7.0 Within 24 Hrs of MRS 10 2.0 VENTRICULAR FUNCTION (EP) EF > 0.50 324 64.8 EF 0.41 to 0.50 76 15.2 EF 0.30 to 0.40 80 16.0 EF < 0.30 20 4.0 VENTRICULAR ANEURYSM 16 3.2 'Angina of recent onset or recent increase in frequency or severity Chest pain at rest while in hospital (New York Heart Association Class IV) 'Myocardial revascularization surgery Percutaneous transluminal coronary angioplasty Ejection fraction Perfusion Techniques The cardiopulmonary bypass (CPB) circuit employed by our group during this study consisted of either a bubble or membrane oxygenator, cardiotomy reservoir, and a 40-micron arterial filter. A variety of commercially available devices in each category were evaluated during the course of this study. An in-line arterial oxygen partial pressure (pa02) sensor with integral temperature monitor (CardioMet 1000 Model)" was also utilized during all perfusions. 6 The CPB circuit prime consisted of lactated Ringer's solution (2,200 ml +/200 ml), bovine lung heparin (5,000 units), a Orange Medical, Inc., Costa Mesa, CA 92626 |
| Starting Page | 106 |
| Ending Page | 116 |
| Page Count | 11 |
| File Format | PDF HTM / HTML |
| Volume Number | 18 |
| Alternate Webpage(s) | http://amsect.smithbucklin.com/JECT/PDFs/1986_volume18/issue2/ject_1986_v18_n2_galbraith.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
