Postgraduate Medicine
ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20
Coronary artery disease in surgical patients Mark J. Corapi MD & Ralph K. Della Ratta MD To cite this article: Mark J. Corapi MD & Ralph K. Della Ratta MD (1992) Coronary artery disease in surgical patients, Postgraduate Medicine, 92:5, 265-272, DOI: 10.1080/00325481.1992.11701497 To link to this article: http://dx.doi.org/10.1080/00325481.1992.11701497
Published online: 17 May 2016.
Submit your article to this journal
View related articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ipgm20 Download by: [The University Of Melbourne Libraries]
Date: 23 June 2016, At: 00:58
-@CME credit article
Coronary artery disease in surgical patients Perioperative management
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
Mark J. Corapi, MD
Ralph K. Della Ratta, MD
Preview In the first article of this pair (page 251), Drs Corapi and Della Ratta discussed preoperative evaluation of ischemic heart disease in patients needing noncardiac surgery. In this article, they address perioperative factors that affect outcome and present an effective approach to management of postoperative myocardial infarction.
The perioperative period is a physiologically stressful time in patients with coronary artery disease (CAD). Major changes occur in adrenergic activity, plasma catecholamine levels, body temperature, pulmonary function, perception of pain, and fluid balance; in addition, there are related changes in heart rate, blood pressure, and intravascular volume.1 All of these factors fluctuate more widely during the postoperative period than before or during surgery, and they can precipitate myocardial ischemia by altering the relationship between myocardial oxygen supply and demand. Therefore, particular attention by a primary care physician to these physiologic stressors during the postoperative period is just as important as preoperative risk assessment and intraoperative physiologic management (table 1). Because of the substantial risk of postoperative cardiac complications in patients who have re-
cently had myocardial infarction, surgery should be delayed for 6 months, if feasible, to allow time for cardiac remodeling. The risk of cardiac complications is particularly great within the first 3 months after infarction. (For a full discussion of the effects of myocardial infarction on patients preparing for noncardiac surgery, see companion article beginning on page 251.)
Coordinating perioperative management When noncardiac surgery is considered high risk for a patient with CAD, effective preoperative communication between the primary care physician and the anesthesiologist is essential for appropriate perioperative management. Clearly, it is the anesthesiologist's role to select the anesthetic and technique best suited to the patient, but it is also important for the primary care physician to understand the risk for cardiac complications inherent to each. 2 Such
understanding allows an informed discussion between the primary care physician and the anesthesiologist regarding the various aspects of perioperative management and hopefully promotes a reduction in the risk of postoperative cardiac complications. GENERAL ANES1HETICS-These agents have both a direct effect on myocardial contractility and an indirect myocardial effect that is mediated through the autonomic nervous system. Halothane (Fluothane) is a stronger myocardial depressant than nitrous oxide. General anesthetic agents also lower the threshold to arrhythmias, halothane more so than enflurane or isoflurane. Use of balanced anesthesia, such as produced by morphine sulfate or fentanyl (Sublimaze) plus nitrous oxide and a muscle relaxant, produces very little myocardial depression. Previously, this type of balanced anesthesia was reserved for cardiac surgery; however, extension of its use to general surgery certainly is one factor that has reduced the rate of postoperative cardiac complications in the last quarter century. INTRAOPERATIVE HEMODYNAMIC MONTIORING--The now
routine use of intraoperative hemodynamic monitoring in
continued
VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE • PERIOPERATIYE MANAGEMENT OF CAD
265
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
In patients with recent myocardial infarction, noncardiac surgery should be delayed at least 3 months and preferably 6 months or more.
Table 1. Guidelines for management of patients with coronary artery disease who need noncardiac surgery Patients with recent myocardial infarction Unless surgery is absolutely urgent, delay at least 3 mo and preferably 6 mo or more Stratify risk of recent infarction according to complications (congestive heart failure, angina, postinfarction angina) Further evaluate risk with preoperative noninvasive diagnostic testing (Holter monitoring, exercise stress testing, dipyridamole-thallium scanning) Consider cardiac catheterization if semiurgent surgery is necessary within 3 mo of infarction Optimize comorbid conditions (eg, chronic obstructive pulmonary disease)
Patients with symptomatic angina If patient is intermediate- or high-risk candidate for postoperative cardiac complications, defer surgery until noninvasive testing defines severity of coronary artery disease Consider exercise stress test, especially in sedentary high-risk patients scheduled for major surgery and in those with previously undiagnosed chest pain syndrome When noninvasive testing suggests poor prognosis, consider coronary angiography preoperatively In high-risk patients, consider CABG or PTCA before noncardiac surgery to reduce risk of postoperative cardiac complications
Stop use of aspirin 7 days preoperatively in most cases·
Initiate and optimize antianginal therapy; postpone or defer surgery, if necessary, to accomplish this
Use hemodynamic monitoring during surgery
Stop use of aspirin 7 days preoperatively in most cases· Orchestrate perioperative dosing of antianginal medication and continue intravenous nitrates or betablocking agents throughout perioperative period when warranted for high-risk patients
CABG, coronary artery bypass grafting; PTCA, percutaneous transluminal coronary angioplasty. *Risk of aspirin-induced platelet dysfunction within 7 days of last dose must be weighed against type of surgery and severity of coronary artery d1sease.
high-risk patients with CAD allows the anesthesiologist to maximize the physiologic determinants of myocardial oxygen demand. Intraoperative monitoring of multiple electrocardiographic leads has become routine in many in-
266
stiturions as a means of identifYing myocardial ischemia. Hemodynamic monitoring during the intraoperative period, including right-sided heart catheterization with a Swan-Ganz catheter and placement of an
arterial line to monitor blood pressure, may be useful in patients with recent myocardial infarction, severe CAD, major complicating risk factors (congestive heart failure, significant aortic stenosis), or anticipated large vol-
PERIOPERATIVE MANAGEMENT OF CAD • VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
At the time of noncardiac surgery in a patient with coronary artery disease, a primary care physician is often called to orchestrate the medical regimen.
ume shifts (such as occur during repair of abdominal aortic aneurysm). Hemodynamic monitoring in these patients should be continued for at least 48 hours postoperatively to enhance medical management. MEDICATIONs-The goal for the control of angina pectoris during the preoperative period is its absence at rest and with mild exertion. Angina should be controlled preoperatively with long-acting nitrate preparations, calcium channel blockers, or beta-blocking agents. Aspirin is often used in the anti-ischemic regimen; however, it may have to be discontinued at least 7 days before surgery to allow the return of normal platelet function. The decision to stop aspirin therapy should be based on the severity of angina and the type of surgery planned. When drug therapy for CAD is introduced or modified during the preoperative period, the primary care physician needs to give assurance that no deleterious effects of the medical regimen (eg, bradycardia, hypotension, congestive heart failure) can contribute to postoperative cardiac morbidity and mortality. If necessary, all but emergency surgery should be delayed to accomplish this goal.
At the time of surgery, the primary care physician is often called on to carefully orchestrate the patient's medical regimen. Long-acting oral preparations are available to treat each class of angina. Patients with CAD should be given their antianginal medications on the morning of surgery with a sip of water; this protects them against ischemia during the intraoperative and immediate postoperative period. When the risk of postoperative cardiac complications is particularly high, the primary care physician may choose to maintain the patient on continuous intravenous infusion of either nitroglycerin (Nitro-Bid IV; Tridil) or a beta-blocking agent (eg, intravenous propranolol hydrochloride [Inderal]) given at a rate of0.5 to 3 mg an hour). Nitroglycerin may also be used in a topical form (Nitro-Bid, Nitrol) in high-risk patients or in patients who were using oral nitrates preoperatively but in whom a prolonged period without oral intake is anticipated postoperatively. After surgery, the oral antianginal regimen should be resumed as soon as feasible. CABG AND PTCA-The decision to use coronary artery bypass
VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE • PERIOPERATIVE MANAGEMENT OF CAD
grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA) before noncardiac surgery to reduce the risk of postoperative cardiac complications must be made on a case-bycase basis. As discussed in the first of these articles, the risk of CABG must be factored into the risk-benefit equation for the noncardiac surgery planned. Additionally, noncardiac surgery cannot be performed until 6 weeks afterCABG. Use ofPTCA in the perioperative period for this purpose has not been studied systematically. Because the risk of complications is lower with PTCA than with CABG, it would seem that PTCA represents a viable therapeutic option in appropriately selected patients. However, the procedure cannot be recommended routinely until controlled therapeutic trials have been undertaken. COPD--Concomitant moderate to severe chronic obstructive pulmonary disease substantially raises the perioperative risk of cardiac complications in patients with CAD. 3 Preoperative therapy for the disease must be maximized in these patients, and prophylaxis against postoperative pulmonary complications must be instituted.
continued on page 271
267
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
The mortality rate accompanying postoperative myocardial infarction is exceedingly high; about half of the deaths occur suddenly and are secondary to arrhythmias.
Postoperative myocardial infarction Primary care physicians need to provide ongoing postoperative observation of high-risk patients with CAD. Emphasis during follow-up should be placed on anticipation of cardiac complications and then on minimizing and managing them if they arise. The first 7 postoperative days have been identified as the period when adverse cardiac events are most likely to occur. 1 The possibility of myocardial infarction is greatest when patients are mobilizing intraoperative fluids, being withdrawn from analgesics, or beginning to walk. Thus, recuperation, especially if it is not progressing smoothly, is more likely to precipitate myocardial infarction than is well-balanced general anesthesia. 4 Although myocardial infarction may occur at any time during the first 7 postoperative days, most infarctions take place between the third and the fifth days. Infarction is silent in 22% to 50% of cases, a range that is comparable to the 20% to 40% noted in nonsurgical patients in the Framingham Heart Study. Dyspnea may be the harbinger of infarction more often than chest pain. 1 Congestive heart failure, hy-
potension, hypertension, confusion, or arrhythmia (supraventricular tachycardia more often than ventricular tachycardia) may be the sole presenting sign or symptom. Although causes other than postoperative myocardial infarction are commonly found for these problems, infarction should be highly suspected if they are detected in a postoperative patient. Recognition of ischemic cardiac events in the early postoperative period is often difficult because of such confounding factors as the use of narcotic analgesics and incisional pain. A patient's ability to communicate symptoms may also be compromised because of the effects of anesthesia and analgesia and maintenance of an endotracheal tube for mechanical ventilation. Special attention to postoperative tachycardia, fever, pain, swings in blood pressure, and fluid management by the medical, surgical, and anesthetic teams may minimize the potential for postoperative ischemic events. High-risk patients should be monitored in an intensive care unit for several days postoperatively. Because, as noted, myocardial ischemia and infarction may be silent or masked by confounding factors in the postoperative
state, an electrocardiogram and cardiac isoenzyme measurements obtained daily may be useful adjuncts in moderate- to high-risk patients to identify postoperative myocardial infarction. However, cardiac isoenzyme measurements must be interpreted in light of the effect of surgery on the enzyme level. The creatine kinase (CK) isoenzyme fraction is most useful for diagnosis, because lactate dehydrogenase and aspartate aminotransferase levels increase after biliary tract surgery and the total CK level is often elevated after orthopedic surgery and as a result of numerous other causes. Occasionally, patients with massive total CK elevations from muscle trauma or other injury may have positive or equivocal CK-MB bands without myocardial damage. Use of an intra-aortic balloon pump can be considered in patients at very high risk, although such use has not been studied in the perioperative serting. The mortality rate accompanying postoperative myocardial infarctions is exceedingly high; in patients with no prior history of infarction, it is about 35%; in those with a previous history, it is 50% to 80%. About half of these deaths occur suddenly and are secondary to arrhythmias. There-
continued
VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE • PERIOPERATNE MANAGEMENT OF CAD
271
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
lnterventional therapy may be needed if hypotension or congestive heart failure complicates myocardial infarction after noncardiac surgery.
fore, any patient with suspicious electrocardiographic changes should also be monitored in the intensive care unit to ensure that intervention for arrhythmias is rapid. When postoperative myocardial infarction occurs, management may include prophylactic intravenous lidocaine (Xylocaine) hydrochloride during the first 48 hours after the infarction. Treatment options for chest pain include parenteral narcotics; sublingual, topical, and intravenous nitrates; and intravenous betablocking agents, such as propranolol and metoprolol tartrate (Lopressor). Even when infarction is silent, prophylactic therapy with topical nitrates and beta-blocking agents should be considered. Topical nitrates (Y2 to 1 in. in paste form) may be applied to the skin at 6- to 8-hour intervals; this formulation may precipitate hypotension, particularly in a volume-depleted patient or one who has inferior myocardial infarction complicated by right ventricular infarction. Propranolol may be given in a 1- to 3-mg intravenous bolus (using no more than 1 mg every 5 minutes) at 4- to 6-hour intervals or as a continuous infusion of 0.5 to 3 mg an hour. If meto-
272
prolol is chosen, a loading dose of 1 mg a minute (to a total of 15 mg in 15 minutes) should be initiated. An oral dose of 100 mg is given 30 minutes after the intravenous bolus and once every 12 hours thereafter. If hypotension or congestive heart failure complicates postoperative infarction, hemodynamic monitoring with a Swan-Ganz catheter is indicated for further management and consideration should be given to interventional therapy.
period. Up to 50% of postoperative myocardial infarctions may be silent, or they may present as congestive heart failure, hypotension, or arrhythmia. Dyspnea is a common finding. All high-risk patients should be monitored in the intensive care unit during the first 7 days after surgery, when adverse cardiac events are most common. Rill
-®
Earn credit on these articles.
See CME Quiz.
Summary With effective communication, optimal use of perioperative therapeutic techniques, and postoperative follow-up, the medical, surgical, and anesthetic teams can prevent or minimize cardiac complications that occur during the postoperative
References 1. Mangano DT, Browner WS, Hollenberg M, et al. Association of perioperative myocardial ischemia with cardiac morbidiry and mortaliry in men undergoing noncardiac surgery. N EnglJ Med 1990;323(26):1781-8 2. Sanfelippo JF. Noncardiac surgery and anesthesia in patienrs with heart disease. Am Fam Physician 1982;26(2):204-12 3. Gross RJ, Kern DE. Cardiovascular disease
A companion article, on preoperative evaluation of patients with coronary artery disease, begins on page 251. Address for correspondence: Mark J. Corapi, MD, Division of General Internal Medicine, Winthrop-University Hospital, 222 Station Plaza North, Mineola, NY 1150 1.
and hypertension. In: Kammerer WS, Gross RJ, eds. Medical consultation: the internist on surgical, obstetric, and psychiatric services. 2d ed. Baltimore: Williams & Wilkins, 1990:107, 128-32 4. Goldman L Cardiac risks and complications of noncardiac surgery. Ann Intern Med 1983;98(4):504-13
PERIOPERATIVE MANAGEMENT OF CAD • VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE
ISSN: 0032-5481 (Print) 1941-9260 (Online) Journal homepage: http://www.tandfonline.com/loi/ipgm20
Coronary artery disease in surgical patients Mark J. Corapi MD & Ralph K. Della Ratta MD To cite this article: Mark J. Corapi MD & Ralph K. Della Ratta MD (1992) Coronary artery disease in surgical patients, Postgraduate Medicine, 92:5, 265-272, DOI: 10.1080/00325481.1992.11701497 To link to this article: http://dx.doi.org/10.1080/00325481.1992.11701497
Published online: 17 May 2016.
Submit your article to this journal
View related articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ipgm20 Download by: [The University Of Melbourne Libraries]
Date: 23 June 2016, At: 00:58
-@CME credit article
Coronary artery disease in surgical patients Perioperative management
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
Mark J. Corapi, MD
Ralph K. Della Ratta, MD
Preview In the first article of this pair (page 251), Drs Corapi and Della Ratta discussed preoperative evaluation of ischemic heart disease in patients needing noncardiac surgery. In this article, they address perioperative factors that affect outcome and present an effective approach to management of postoperative myocardial infarction.
The perioperative period is a physiologically stressful time in patients with coronary artery disease (CAD). Major changes occur in adrenergic activity, plasma catecholamine levels, body temperature, pulmonary function, perception of pain, and fluid balance; in addition, there are related changes in heart rate, blood pressure, and intravascular volume.1 All of these factors fluctuate more widely during the postoperative period than before or during surgery, and they can precipitate myocardial ischemia by altering the relationship between myocardial oxygen supply and demand. Therefore, particular attention by a primary care physician to these physiologic stressors during the postoperative period is just as important as preoperative risk assessment and intraoperative physiologic management (table 1). Because of the substantial risk of postoperative cardiac complications in patients who have re-
cently had myocardial infarction, surgery should be delayed for 6 months, if feasible, to allow time for cardiac remodeling. The risk of cardiac complications is particularly great within the first 3 months after infarction. (For a full discussion of the effects of myocardial infarction on patients preparing for noncardiac surgery, see companion article beginning on page 251.)
Coordinating perioperative management When noncardiac surgery is considered high risk for a patient with CAD, effective preoperative communication between the primary care physician and the anesthesiologist is essential for appropriate perioperative management. Clearly, it is the anesthesiologist's role to select the anesthetic and technique best suited to the patient, but it is also important for the primary care physician to understand the risk for cardiac complications inherent to each. 2 Such
understanding allows an informed discussion between the primary care physician and the anesthesiologist regarding the various aspects of perioperative management and hopefully promotes a reduction in the risk of postoperative cardiac complications. GENERAL ANES1HETICS-These agents have both a direct effect on myocardial contractility and an indirect myocardial effect that is mediated through the autonomic nervous system. Halothane (Fluothane) is a stronger myocardial depressant than nitrous oxide. General anesthetic agents also lower the threshold to arrhythmias, halothane more so than enflurane or isoflurane. Use of balanced anesthesia, such as produced by morphine sulfate or fentanyl (Sublimaze) plus nitrous oxide and a muscle relaxant, produces very little myocardial depression. Previously, this type of balanced anesthesia was reserved for cardiac surgery; however, extension of its use to general surgery certainly is one factor that has reduced the rate of postoperative cardiac complications in the last quarter century. INTRAOPERATIVE HEMODYNAMIC MONTIORING--The now
routine use of intraoperative hemodynamic monitoring in
continued
VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE • PERIOPERATIYE MANAGEMENT OF CAD
265
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
In patients with recent myocardial infarction, noncardiac surgery should be delayed at least 3 months and preferably 6 months or more.
Table 1. Guidelines for management of patients with coronary artery disease who need noncardiac surgery Patients with recent myocardial infarction Unless surgery is absolutely urgent, delay at least 3 mo and preferably 6 mo or more Stratify risk of recent infarction according to complications (congestive heart failure, angina, postinfarction angina) Further evaluate risk with preoperative noninvasive diagnostic testing (Holter monitoring, exercise stress testing, dipyridamole-thallium scanning) Consider cardiac catheterization if semiurgent surgery is necessary within 3 mo of infarction Optimize comorbid conditions (eg, chronic obstructive pulmonary disease)
Patients with symptomatic angina If patient is intermediate- or high-risk candidate for postoperative cardiac complications, defer surgery until noninvasive testing defines severity of coronary artery disease Consider exercise stress test, especially in sedentary high-risk patients scheduled for major surgery and in those with previously undiagnosed chest pain syndrome When noninvasive testing suggests poor prognosis, consider coronary angiography preoperatively In high-risk patients, consider CABG or PTCA before noncardiac surgery to reduce risk of postoperative cardiac complications
Stop use of aspirin 7 days preoperatively in most cases·
Initiate and optimize antianginal therapy; postpone or defer surgery, if necessary, to accomplish this
Use hemodynamic monitoring during surgery
Stop use of aspirin 7 days preoperatively in most cases· Orchestrate perioperative dosing of antianginal medication and continue intravenous nitrates or betablocking agents throughout perioperative period when warranted for high-risk patients
CABG, coronary artery bypass grafting; PTCA, percutaneous transluminal coronary angioplasty. *Risk of aspirin-induced platelet dysfunction within 7 days of last dose must be weighed against type of surgery and severity of coronary artery d1sease.
high-risk patients with CAD allows the anesthesiologist to maximize the physiologic determinants of myocardial oxygen demand. Intraoperative monitoring of multiple electrocardiographic leads has become routine in many in-
266
stiturions as a means of identifYing myocardial ischemia. Hemodynamic monitoring during the intraoperative period, including right-sided heart catheterization with a Swan-Ganz catheter and placement of an
arterial line to monitor blood pressure, may be useful in patients with recent myocardial infarction, severe CAD, major complicating risk factors (congestive heart failure, significant aortic stenosis), or anticipated large vol-
PERIOPERATIVE MANAGEMENT OF CAD • VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
At the time of noncardiac surgery in a patient with coronary artery disease, a primary care physician is often called to orchestrate the medical regimen.
ume shifts (such as occur during repair of abdominal aortic aneurysm). Hemodynamic monitoring in these patients should be continued for at least 48 hours postoperatively to enhance medical management. MEDICATIONs-The goal for the control of angina pectoris during the preoperative period is its absence at rest and with mild exertion. Angina should be controlled preoperatively with long-acting nitrate preparations, calcium channel blockers, or beta-blocking agents. Aspirin is often used in the anti-ischemic regimen; however, it may have to be discontinued at least 7 days before surgery to allow the return of normal platelet function. The decision to stop aspirin therapy should be based on the severity of angina and the type of surgery planned. When drug therapy for CAD is introduced or modified during the preoperative period, the primary care physician needs to give assurance that no deleterious effects of the medical regimen (eg, bradycardia, hypotension, congestive heart failure) can contribute to postoperative cardiac morbidity and mortality. If necessary, all but emergency surgery should be delayed to accomplish this goal.
At the time of surgery, the primary care physician is often called on to carefully orchestrate the patient's medical regimen. Long-acting oral preparations are available to treat each class of angina. Patients with CAD should be given their antianginal medications on the morning of surgery with a sip of water; this protects them against ischemia during the intraoperative and immediate postoperative period. When the risk of postoperative cardiac complications is particularly high, the primary care physician may choose to maintain the patient on continuous intravenous infusion of either nitroglycerin (Nitro-Bid IV; Tridil) or a beta-blocking agent (eg, intravenous propranolol hydrochloride [Inderal]) given at a rate of0.5 to 3 mg an hour). Nitroglycerin may also be used in a topical form (Nitro-Bid, Nitrol) in high-risk patients or in patients who were using oral nitrates preoperatively but in whom a prolonged period without oral intake is anticipated postoperatively. After surgery, the oral antianginal regimen should be resumed as soon as feasible. CABG AND PTCA-The decision to use coronary artery bypass
VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE • PERIOPERATIVE MANAGEMENT OF CAD
grafting (CABG) or percutaneous transluminal coronary angioplasty (PTCA) before noncardiac surgery to reduce the risk of postoperative cardiac complications must be made on a case-bycase basis. As discussed in the first of these articles, the risk of CABG must be factored into the risk-benefit equation for the noncardiac surgery planned. Additionally, noncardiac surgery cannot be performed until 6 weeks afterCABG. Use ofPTCA in the perioperative period for this purpose has not been studied systematically. Because the risk of complications is lower with PTCA than with CABG, it would seem that PTCA represents a viable therapeutic option in appropriately selected patients. However, the procedure cannot be recommended routinely until controlled therapeutic trials have been undertaken. COPD--Concomitant moderate to severe chronic obstructive pulmonary disease substantially raises the perioperative risk of cardiac complications in patients with CAD. 3 Preoperative therapy for the disease must be maximized in these patients, and prophylaxis against postoperative pulmonary complications must be instituted.
continued on page 271
267
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
The mortality rate accompanying postoperative myocardial infarction is exceedingly high; about half of the deaths occur suddenly and are secondary to arrhythmias.
Postoperative myocardial infarction Primary care physicians need to provide ongoing postoperative observation of high-risk patients with CAD. Emphasis during follow-up should be placed on anticipation of cardiac complications and then on minimizing and managing them if they arise. The first 7 postoperative days have been identified as the period when adverse cardiac events are most likely to occur. 1 The possibility of myocardial infarction is greatest when patients are mobilizing intraoperative fluids, being withdrawn from analgesics, or beginning to walk. Thus, recuperation, especially if it is not progressing smoothly, is more likely to precipitate myocardial infarction than is well-balanced general anesthesia. 4 Although myocardial infarction may occur at any time during the first 7 postoperative days, most infarctions take place between the third and the fifth days. Infarction is silent in 22% to 50% of cases, a range that is comparable to the 20% to 40% noted in nonsurgical patients in the Framingham Heart Study. Dyspnea may be the harbinger of infarction more often than chest pain. 1 Congestive heart failure, hy-
potension, hypertension, confusion, or arrhythmia (supraventricular tachycardia more often than ventricular tachycardia) may be the sole presenting sign or symptom. Although causes other than postoperative myocardial infarction are commonly found for these problems, infarction should be highly suspected if they are detected in a postoperative patient. Recognition of ischemic cardiac events in the early postoperative period is often difficult because of such confounding factors as the use of narcotic analgesics and incisional pain. A patient's ability to communicate symptoms may also be compromised because of the effects of anesthesia and analgesia and maintenance of an endotracheal tube for mechanical ventilation. Special attention to postoperative tachycardia, fever, pain, swings in blood pressure, and fluid management by the medical, surgical, and anesthetic teams may minimize the potential for postoperative ischemic events. High-risk patients should be monitored in an intensive care unit for several days postoperatively. Because, as noted, myocardial ischemia and infarction may be silent or masked by confounding factors in the postoperative
state, an electrocardiogram and cardiac isoenzyme measurements obtained daily may be useful adjuncts in moderate- to high-risk patients to identify postoperative myocardial infarction. However, cardiac isoenzyme measurements must be interpreted in light of the effect of surgery on the enzyme level. The creatine kinase (CK) isoenzyme fraction is most useful for diagnosis, because lactate dehydrogenase and aspartate aminotransferase levels increase after biliary tract surgery and the total CK level is often elevated after orthopedic surgery and as a result of numerous other causes. Occasionally, patients with massive total CK elevations from muscle trauma or other injury may have positive or equivocal CK-MB bands without myocardial damage. Use of an intra-aortic balloon pump can be considered in patients at very high risk, although such use has not been studied in the perioperative serting. The mortality rate accompanying postoperative myocardial infarctions is exceedingly high; in patients with no prior history of infarction, it is about 35%; in those with a previous history, it is 50% to 80%. About half of these deaths occur suddenly and are secondary to arrhythmias. There-
continued
VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE • PERIOPERATNE MANAGEMENT OF CAD
271
Downloaded by [The University Of Melbourne Libraries] at 00:58 23 June 2016
lnterventional therapy may be needed if hypotension or congestive heart failure complicates myocardial infarction after noncardiac surgery.
fore, any patient with suspicious electrocardiographic changes should also be monitored in the intensive care unit to ensure that intervention for arrhythmias is rapid. When postoperative myocardial infarction occurs, management may include prophylactic intravenous lidocaine (Xylocaine) hydrochloride during the first 48 hours after the infarction. Treatment options for chest pain include parenteral narcotics; sublingual, topical, and intravenous nitrates; and intravenous betablocking agents, such as propranolol and metoprolol tartrate (Lopressor). Even when infarction is silent, prophylactic therapy with topical nitrates and beta-blocking agents should be considered. Topical nitrates (Y2 to 1 in. in paste form) may be applied to the skin at 6- to 8-hour intervals; this formulation may precipitate hypotension, particularly in a volume-depleted patient or one who has inferior myocardial infarction complicated by right ventricular infarction. Propranolol may be given in a 1- to 3-mg intravenous bolus (using no more than 1 mg every 5 minutes) at 4- to 6-hour intervals or as a continuous infusion of 0.5 to 3 mg an hour. If meto-
272
prolol is chosen, a loading dose of 1 mg a minute (to a total of 15 mg in 15 minutes) should be initiated. An oral dose of 100 mg is given 30 minutes after the intravenous bolus and once every 12 hours thereafter. If hypotension or congestive heart failure complicates postoperative infarction, hemodynamic monitoring with a Swan-Ganz catheter is indicated for further management and consideration should be given to interventional therapy.
period. Up to 50% of postoperative myocardial infarctions may be silent, or they may present as congestive heart failure, hypotension, or arrhythmia. Dyspnea is a common finding. All high-risk patients should be monitored in the intensive care unit during the first 7 days after surgery, when adverse cardiac events are most common. Rill
-®
Earn credit on these articles.
See CME Quiz.
Summary With effective communication, optimal use of perioperative therapeutic techniques, and postoperative follow-up, the medical, surgical, and anesthetic teams can prevent or minimize cardiac complications that occur during the postoperative
References 1. Mangano DT, Browner WS, Hollenberg M, et al. Association of perioperative myocardial ischemia with cardiac morbidiry and mortaliry in men undergoing noncardiac surgery. N EnglJ Med 1990;323(26):1781-8 2. Sanfelippo JF. Noncardiac surgery and anesthesia in patienrs with heart disease. Am Fam Physician 1982;26(2):204-12 3. Gross RJ, Kern DE. Cardiovascular disease
A companion article, on preoperative evaluation of patients with coronary artery disease, begins on page 251. Address for correspondence: Mark J. Corapi, MD, Division of General Internal Medicine, Winthrop-University Hospital, 222 Station Plaza North, Mineola, NY 1150 1.
and hypertension. In: Kammerer WS, Gross RJ, eds. Medical consultation: the internist on surgical, obstetric, and psychiatric services. 2d ed. Baltimore: Williams & Wilkins, 1990:107, 128-32 4. Goldman L Cardiac risks and complications of noncardiac surgery. Ann Intern Med 1983;98(4):504-13
PERIOPERATIVE MANAGEMENT OF CAD • VOL 92/NO 5/0CTOBER 1992/POSTGRADUATE MEDICINE
