Risk of Anesthesia in Patients with Heart Disease
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Risk of anesthesia in patients with heart disease Patients with moderate to severe valvular dys- function represent a challenge to anesthesiologists because of their specific cardiac pathology. Certain Sait Tarhan, M.D. cardiac lesions increase the risk of operation even though cardiac reserve seems good. Patients with Rochester, Minnesota severe aortic stenosis or incompetence are particu- larly susceptible to the development of ventricular fibrillation. Patients with mitral stenosis who have few symptoms can tolerate general surgical proce- dures reasonably well, but care should be taken not to increase the left atrial pressure and consequent pulmonary edema.1 Management of these patients requires under- standing of the altered cardiovascular state, hemo- dynamic impairment caused by the anatomic le- sions, and their altered response to the support of cardiac function. Hemodynamic requirements of different lesions dictate the appropriate choice of anesthetic drugs and techniques. Careful titration of agents to preserve circulatory stability is essential while the patient is undergoing surgery. Selection of anesthetic agents for the patient with certain types of cardiac lesions is also important, such as enflurane and halothane, which are associated with junctional rhythm. Gallamine and ketamine may increase the heart rate; therefore, those agents may not be the optimum choice for tight mitral stenosis. 50 Downloaded from www.ccjm.org on September 26, 2021. For personal use only. All other uses require permission. Spring 1981 Risk of anesthesia 51 However, narcotics would not depress and noncardiac surgery without having contractility and change the rhythm, postoperative myocardial infarction and therefore would be more suitable. than patients with coronary heart dis- The number of patients who have valve ease and those who did not have coro- disease and undergo operation has de- nary artery bypass graft surgery.5 clined in the past decade because of the In a study of myocardial infarction progress made in replacing diseased after general anesthesia in which the valves with prosthetic valves. However, diagnosis was supported by electrocar- replacement of an old, damaged valve diography and appropriate enzyme with a prosthesis does not guarantee studies, patients with previous myocar- perfect myocardial function. A degree dial infarctions, 28 of 422 (6.6%) expe- of cardiac compromise still may exist, rienced another infarction during the and therefore these patients require spe- first week after the operation.6 They had cial care. a 50-fold greater risk of reinfarction The most common cardiac disease than patients who did not have a history among patients having anesthesia and of myocardial infarction; of 32,455 pa- surgery is coronary heart disease and tients, only 43 (0.13%) had infarctions previous myocardial infarction. The after surgery. high incidence and pathogenic mecha- Fifty-four percent of them died as a nisms are discussed. result of reinfarction. The relation be- One million three hundred thousand tween time of infarct and surgery is persons experience myocardial infarc- shown in Table 1 and the relation of tions each year in the United States.2"4 reinfarction to the site of surgery is Therefore, the number of patients with shôwn in Table 2. coronary heart disease or myocardial Since this study, new anesthetic infarction who require some form of agents and techniques have been devel- surgical operation is increasing steadily oped; major changes in medical man- and these patients present problems re- agement have come about and high-risk lated to the specific cardiac pathologic patients are more often monitored in findings. intensive care units. Therefore, all these Some authors have assumed that pa- measures should reduce the reinfarction tients with coronary artery disease and ratio. To verify this assumption, we re- good cardiac reserve tolerate general cently conducted another study; how- surgical procedures well,1 but others have reported that presence of three- Table 1. Relation between time of vessel coronary artery disease is associ- infarction and surgery ated with approximately 20% risk of No. of postoperative No. of patients myocardial infarction after anesthesia reinfarctions (%) and noncardiac operations. Some stud- Time of surgery, mo 1972 1978 1972 1978 ies indicate that risk of postoperative myocardial infarction after noncardiac 0-3 8 15 3 (38) 4(27) 4-6 19 18 3(16) 2(11) operations in patients with one- or two- 7-12 42 31 2(5) 2(6) vessel coronary artery disease appears to 13-18 27 30 1 (4) 1 (3) 3 be low. Patients with coronary heart 19-24 21 17 1 (5) 1 (6) disease who had undergone coronary >24 232 383 11 (5) 15(4) artery bypass graft surgery have a Unknown 73 JJ3 7 (10) 11 (12) greater chance to undergo anesthesia Total 422 587 28 (7) 36 (6) Downloaded from www.ccjm.org on September 26, 2021. For personal use only. All other uses require permission. 52 Cleveland Clinic Quarterly Vol. 48, No. 1 Table 2. Relation of myocardial reinfarction to site of surgery No. of patients No. of reinfarctions (%) 1972 1978 1972 1978 Great vessels 54 69 5(9) 11 (16)* Other intrathoracic 18 24 8(44) 3 (13)t Upper abdominal 59 84 3 (5) 7(8)t Total of above 131 177 16 (12)* 21 (12) Other sites 291 410 12 (4)* 15 ffl*t Total 422 587 28 (7) 36 (6) *p< 0.001. t p < 0.05. ever, the results were disappointing.7 episodes. However, a 30% or more in- The incidence and severity of reinfarc- crease in blood pressure did not increase tions were identical with those in the the reinfarction ratio significantly (p < previous study (6.1% reinfarctions). The 0.15). Duration of anesthesia increased time of the infarction and surgery the reinfarction rate for the entire group showed the same relationship as the pre- from 1.9% for procedures lasting less vious study (Table I). Mortality among than one hour to 16.7% for procedures these patients was 69%. It was apparent lasting more than 6 hours (p < 0.001). in both studies that the incidence of a Twenty-five percent of the patients in new myocardial infarction stabilized the second study were admitted to the after a 6-month interval. In the second intensive care unit after surgery, which study the relation of reinfarction to the did not influence the reinfarction ratio. site of surgery also gave similar results (Table 2). In both studies, age, sex, an- Discussion esthetic techniques, and site of previous Reinfarction after anesthesia and sur- infarct had no significant effect on rein- gery is a serious complication with high farction ratio. mortality. Elective operations should be In the second study, we tried to cor- delayed at least 6 months after the first relate preoperative hypertension requir- infarct. We have not been able to reduce ing medical treatment, diabetes, angina, (statistically) the number of reinfarc- and blood pressure changes during an- tions after anesthesia and surgery, de- esthesia to the reinfarctions. Patients spite apparent major changes in periop- with preoperative hypertension had sig- erative management. nificantly higher reinfarction rates than The pathogenic mechanism of myo- normotensive patients (9.4% versus cardial infarction is still largely specu- 4.7%, p < 0.05). Diabetes and angina lative.8 It is reasonably easy to explain did not increase the infarction rate. Of the occurrence of myocardial infarction 145 patients in whom systolic pressures in patients with atherosclerotic coronary decreased by at least 30% one or more vessels with superimposed hypotension times for 10 minutes or more during or hypertension, or an acute thrombosis, anesthesia, the reinfarction rate was sig- and this could be accounted for in some nificantly higher (15.2% versus 3.2%, p of our cases. Yet, some infarctions have < 0.001) than for patients who did not occurred without any hemodynamic have such intraoperative hypotensive changes during or after surgery. Downloaded from www.ccjm.org on September 26, 2021. For personal use only. All other uses require permission. Spring 1981 Risk of anesthesia 53 The critical degree of narrowing of coronary vasospasm during and after the coronary arteries is about an 80% anesthesia. This subject merits further diameter reduction. Narrowing above investigation. 80% is consistently associated with limi- References tations of blood flow and less than 80% 1. Kirklin JW. Circulation and cardiac failure. narrowing causes flow limitations only 9 In: American College of Surgeons, Commit- under conditions of increased demand. tee on pre and postoperative care. Manual of Myocardial infarction can be precip- Preoperative and Postoperative Care. 2nd ed. itated by coronary vasospasm, usually Philadelphia: WB Saunders Co, 1971: 195- but not always superimposed on ather- 210. osclerotic plaque, which may obstruct 2. Hillis LD, Braunwald E. Myocardial ischemia (first of three parts). N Engl J Med 1977; 296: 60% to 80% of the luminal diameter, an 971-8. acute increase of that narrowing from 3. Hillis LD, Braunwald E. Myocardial ischemia 90% to 100% by vasoconstriction, or the (second of three parts). N Engl J Med 1977; addition of a relatively small thrombus9 296: 1034-41. would complete the process. This path- 4. Hillis LD, Braunwald E. Myocardial ischemia (third of three parts). N Engl J Med 1977; ogenic mechanism may be operative on 2%: 1093-6. patients during and after anesthesia. 5. Mahar LJ, Steen PA, Tinker JH, Vlietstra Several different factors can cause cor- RE, Smith HC, Pluth JR. Perioperative myo- onary artery spasm such as an increase cardial infarction in patients with coronary of calcium ion in the blood,10 para- artery disease with and without aorta-coro- nary artery bypass grafts. J Thorac Cardio- sympathomimetic agents, hyperven- vasc Surg 1978; 76: 533-7. 12 tilation, increased parasympathetic 6. Tarhan S, Moffitt EA, Taylor WF, Giuliani 10 tone, and released thromboxane A2 by ER.