Noncardiac Surgery in the Elderly Patient with Cardiovascular Disease

Perioperative Care of the Older Patient

0749-0690/90 $0.00 + .20

Noncardiac Surgery in the Elderly Patient with Cardiovascular Disease Howard H . Weitz, MD*

Cardiovascular disease is a major medical problem of the elderly. It is the leading cause of death in patients 65 years of age or older, with 80-85% of deaths due to heart disease as a result of ischemic heart disease. It is estimated that 55% of men and 45% of women aged 65 or older have heart disease. In men in this age group, it is estimated that 20% have ischemic heart disease, 10% have hypertensive heart disease, 7% have combined ischemic and hypertensive heart disease, and 4% have valvular disease. In elderly women, 14% have hypertensive heart disease, 12% have ischemic heart disease, 7% have combined hypertensive and ischemic heart disease, .~ of this high prevalence of heart and 6% have valvular d i ~ e a s e Because disease in the elderly, its presence should be actively sought in the patient who undergoes noncardiac surgery.

CARDIAC PHYSIOLOGY AND AGING A variety of physiologic cardiovascular changes accompany aging. Cardiac pump function at rest is often preserved.18 The response of cardiac output to exercise and stress, however, is altered. In healthy young patients cardiac output during stress may rise 10-25%, whereas in the elderly it often does not rise or may even decrease.1° The reasons for this change in cardiac output response are probably multifactorial. Maximal heart rate decreases with increasing age. Because cardiac output is dependent upon heart rate and stroke volume, the elderly increase cardiac output primarily by increasing stroke volume. This is attained by increasing end-diastolic volume.53 While this is a normal compensatory response, it may result in perioperative congestive heart failure in the elderly patient who is given excessive fluid during surgery, who has left ventricular dysfunction prohibiting an increase in left ventricular volume, or who has aortic stenosis with a "fixed" cardiac output. Another potential risk of the decreased heart rate response in the

*Clinical Associate Professor of Medicine, Divisions of Cardiology and Internal Medicine, Department of Medicine, Jefferson Medical College, Philadelphia, Pennsylvania Clinics in Geriatric Medicine-Vol.

6, No. 3, August 1990

511

elderly is that it may result in an inability to fully compensate for perioperative hypovolemia andlor hypoten~ion.~~ The normal response to perioperative stress, pain, and intravascular volume loss is an increase in circulating catecholamines which serve to conserve water and increase heart rate and stroke volume to maintain perfusion of vital organs. The geriatric patient is less responsive to the effects of circulating catecholamines, probably as a result of age-related changes of the cardiac beta-receptor. For this reason hemodynamic instability during surgery may develop. The normal response to an increase in circulating catecholamines is an increase in peripheral vascular resistance as well as myocardial oxygen demand. For the patient with ischemic heart disease, this may serve to provoke myocardial ischemia, may lead to congestive heart failure in patients with left ventricular dysfunction, or may result in arrhythmias in the patient with electrically unstable myocardium. Other cardiovascular changes of aging that may diminish the geriatric patient's cardiovascular reserve in the perioperative period are the presence of left ventricular hypertrophy with its associated decreased left ventricular compliance, increases in left and right ventricular end-diastolic and pulmonary artery pressures, elevated peripheral vascular resistance, diminished carotid sinus reflex, and elevated systolic blood pressure.

ASSESSMENT OF CARDIAC RISK In 1977a risk factor index was devised by Goldman utilizing prospective analysis for patients over age 40 undergoing noncardiac surgery.22A total of 1001 patients were assessed; 60% were over age 60, 30% were over age 70, and 10% were over age 80. Overall mortality was 5.9%, with death due to a cardiac cause at 1.9% The study identified nine risk factors that were associated with an increased risk of perioperative complication (myocardial infarction, myocardial ischemia, ischemic pulmonary edema, ventricular tachycardia, or death). Multivariate analysis was used to weight the risk factors and assign "risk points" to each factor to allow quantitation of overall cardiac risk. Age greater than 70 was one of nine risk factors identified. The other risk factors were prior myocardial infarction within the preceding 6 months, presence of a third heart sound or jugular venous distention, important valvular aortic stenosis, rhythm other than sinus rhythm or the presence of atrial premature contractions on the preoperative electrocardiogram, more than five ventricular premature contractions per minute prior to surgery, abdominal, thoracic, or aortic surgery, emergency surgery, and poor general medical condition (Table 1). Utilizing the patient's total points a scoring index was devised to enable stratification of patients into one offour risk groups according to the incidence of perioperative life-threatening cardiac complications and mortality (Table 2). A risk factor index of this type was attractive because it utilized readily obtainable, clinically relevant data to arrive at an estimation of surgical risk. Several of the factors were potentially reversible (third heart sound or jugular venous distention, myocardial infarction within the preceding 6 months, important valvular aortic stenosis, poor general medical condition), sug-

Table 1. Computation of the Cardiac Risk Index ITEM

POINTS

History Age greater than 70 Myocardial infarction within 6 months Physical S3 or jugular venous distention Important valvular aortic stenosis Electrocardiogram Rhythm other than sinus or the presence of atrial premature contractions on the preoperative ECG More than 5 VPCs per minute at any time prior to surgery Medical status Poor general medical status P0,<60 or PCO2>50 K<3.0 or HCO3<20 mEq/L BUN>50 or creatinine >3 mg/dl Abnormal SGOT Chronic liver disease Bedridden due to noncardiac cause Operation Intraperitoneal, intrathoracic, aortic surgery Emergency surgery Reprinted by permission of the New England Journal of Medicine from Goldman L, Caldera DL, Nussbaum SR, et al: Multifactorial index of cardiac risk in noncardiac surgical procedures. N Engl J Med 297345, 1977.

rresting that correction of these factors could be associated with a decrease riskvof cardiac com~lication.Also of clinical im~ortancewas the identification of factors that wire found not to be ofsignifidancein the determination of cardiac risk. They included the presence of controlled diabetes mellitus, controlled hypertension with diastolic blood pressure 5110 mm Hg, chronic stable angina, and hyperlipidemia. It is important to note that patients who underwent transurethral resection of the prostate, a common surgical procedure in the geriatric population, were not included in this study. The original risk factor index has been reevaluated several times since its original description (Table 2). In 1984 Zeldin prospectively followed 1140 patients utilizing the clinical variables, risk points, and risk groups of the Table 2. Risk of Cardiac Complication in Noncardiac Surgery CLASS (POINTS)

GOLDMAN DATA*

ZELDIN

DATAt

DETSKY DATA$

1% 1% 6% I (0-5) 11 (6-12) 7% 3% 7% 111 (13-25) 14% 15% 20% IV (>25) 78% 30% 100% *Unselected noncardiac surgery patients>40 years old. tunselected noncardiac surgery patients>40 years old. $Patients referred for preoperative medical consultation. Adapted from Goldman L: Multifactorial index of cardiac risk in noncardiac surgery: Ten year status report. J Cardiothorac Anesth 1:237-244, 1987; with permission.

original risk factor index. The cardiac risks were similar to that of the original index for groups I, 11, and 111; however, the risk for the high risk group IV was approximately one half as high as in the Goldman series, probably as a result of enhanced identification and more intense perioperative care of the high-risk patient.77In 1985 Gerson evaluated a series of patients aged 65 or older and found that an inability to do 2 minutes of bicycle exercise in the supine position and raise the heart rate greater than 99 beats per minute (off beta-blocking agents) was the strongest predictor of perioperative cardiac complications or death. The majority of patients who could not exercise were limited by noncardiac causes, e.g., muscle weakness, joint immobility, and dementia. l7 It is unclear whether this increased cardiac risk was due to poor general medical status or cardiac dysfunction. In 1987 Detsky further confirmed the utility of the cardiac risk index in a group of higher risk patients who were referred for preoperative evaluation and found that, in addition to the risk factors identified by Goldman, significant risk factors were Canadian Cardiovascular Society class 3 angina (angina walking one to two blocks on a level surface or climbing one flight of stairs) or class 4 angina (angina with any activity) within 2 weeks prior to surgery, unstable angina within 3 months preceding surgery, and alveolar pulmonary edema (Table 3).l2 Although the multifactorial risk index is helpful in preoperative risk stratification, the significance of several of the clinical variables has changed since the index was initially described in 1977. These variables are myocardial infarction within the preceding 6 months, greater than five ventricular premature contractions per minute prior to surgery, important valvular aortic stenosis, and aortic surgery. Recently a decline in the incidence of perioperative myocardial infarction has been noted. Tarhan reported a series of patients who underwent general anesthesia in 1967 and 1968 and found a 37% reinfarction rate in patients operated on within 3 months of myocardial infarction, a 16% reinfarction rate if surgery was done in the fourth to sixth month postinfarction, and an approximately 5% incidence of perioperative reinfarction if surgery . ~ ~ reevalwas done 6 or more months following myocardial i n f a r ~ t i o nWhen uated in 1974-1975 by Steen, this reinfarction rate was not significantly different, with a reinfarction rate of 27% when surgery was performed within 3 months of infarction, 11% in months 4 to 6 following infarction, and 5% if surgery was done more than 6 months following myocardial i n f a r c t i ~ n . ~ ~ In following a group of patients, the majority of whom underwent invasive hemodynamic monitoring in the perioperative period in addition to having available beta-blocking drugs, dopamine, and intravenous nitroglycerine, Rao noted a significant decrease in the incidence of perioperative reinfarction of 5.7% in the first 3 months following myocardial infarction and 2.3% in months 4 to 6.52Also of significance is risk stratification following myocardial infarction. Patients who have an uncomplicated post-myocardial infarction course and have no evidence of significant left ventricular dysfunction, as quantitated by radionuclide ventriculography, as well as no evidence of myocardial ischemia, as documented by exercise electrocardiography, have a less than 2% one-year cardiac mortality. It is our opinion that these patients will have a lower incidence of cardiac morbidity and mortality than the high-

Table 3. Modified Multifactorial Risk Index VARIABLE

Coronary Artery Disease Myocardial infarction within 6 months Myocardial infarction more than 6 months Canadian Cardiovascular Society angina Class 3 Class 4 Unstable angina within 3 months Alveolar pulmonary edema Within 1 week Ever Valvular disease Critical aortic stenosis Arrhythmias Sinus plus atrial premature beats or rhythm other than sinus on preoperative electrocardiogram More than 5 VPCs per minute at any time prior to surgery Medical status Poor general medical status: Po2<60 or Pco2>50 K<3.0 or HC0,<20 mEq/L BUN>!% or creatinine >3 mgldl Abnormal SCOT Chronic liver disease Bedridden due to noncardiac cause Age Age over 70 years Operation Emergency operation

POINTS

10 5

10 20 10 10 5 20

5 5

5

5 10

From Detsky AS, Abrams H, McLaughlin J, et al: Predicting cardiac complications in patients undergoing non-cardiac surgery. J Gen Intern Med 1:211, 1986; with permission.

risk patient when operated on in the 6 months following myocardial infarction. Ventricular premature contractions are a risk factor for sudden death in the post-myocardial infarction patient and the patient with severe left In the otherwise healthy patient without evidence ventricular dysf~nction.~3 of structural heart disease, the presence of asymptomatic complex ventricular ectopy is not associated with an increase in cardiac morbidity or mortality.33 Therefore, it is our opinion that the healthy patient with ventricular premature contractions and no evidence of heart disease is probably not at increased risk of cardiac complication in the perioperative period. Important valvular aortic stenosis was determined by physical examination-derived criteria for the initial multifactorial risk index. In the elderlv patient decreased vascular elasticity as well as calcification and sclerosis of the aortic valve make the distinction between significant aortic stenosis and the innocent murmur of aortic sclerosis difficult. Doppler echocardiography is a readily available technique to estimate the aortic valve gradient in the preoperative period.49Also a recent report from the Mayo Clinic has shown that in a selected group of patients (mean age 73 years) with severe aortic

stenosis, surgery can be performed without excessive cardiac morbidity and mortality. This has been attributed to advances in anesthetic technique and cardiac monitoring. 46 Jeffrey et al, when applying the multifactorial risk index to patients who underwent abdominal aortic aneurysm repair, found that the initial index underestimated the risk of cardiac complication in the low risk group I by about 40%.30

ANESTHESIA CONSIDERATIONS General anesthesia provides the best control of the cardiorespiratory system and is usually administered by combining inhalation and intravenous agents. The decreased cardiac output response to the stress of surgery in the geriatric patient may delay the distribution of intravenous agents as well as their clearance. This may result in a delayed onset and prolonged duration of anesthesia. Conversely, a cardiac output-related decrease in pulmonary circulation time may decrease the uptake of inhaled anesthesia from the alveoli, resulting in a higher alveolar partial pressure of these agents and a more rapid onset of their action. Commonly used inhalation agents are nitrous oxide, halothane, enflurane, and isoflurane. These agents may produce myocardial depression in a dose-dependent fashion, with nitrous oxide and isoflurane the least depressant and halothane the most.41The myocardial depression of nitrous oxide is usually not clinically evident because it is compensated by reflex sympathetic peripheral vasoconstriction, which serves to maintain blood pressure. Halothane and enflurane produce peripheral vasodilation in addition to myocardial depression, which may result in hypotension in the patient who has intravascular volume depletion, who is taking medication that results in arterial or venous vasodilation, or who has left ventricular dysfunction.24.37 In the patient with cardiac dysfunction, hemodynamically stable general anesthesia can usually be achieved with the use of nitrous oxide and opioids.61 Fentanyl is an opioid commonly used and is probably the least cardiodepressive of all opioids in the elderly. Injection of barbiturates or benzodiazepines is the most common means for induction of general anesthesia. Barbiturates may depress cardiac output and do so to a greater extent in the elderly. This decrease in cardiac output may result in delayed distribution and clearance of barbiturate, resulting in delayed onset of action and prolonged drug e f f e ~ tBarbiturates .~ may also result in peripheral vasodilation and hypotension. The elderly patient is more sensitive to benzodiazepines and has an age-related impairment of hepatic metabolism with prolonged drug effect, but this is associated with minimal hemodynamic or cardiac impairment. 26 Muscle relaxants used in general anesthesia have varied cardiac effects. Pancuronium has a vagolytic effect that may increase heart rate and cardiac output. Succinylcholine has minimal cardiac effect. The decreased cardiac output response to stress in the elderly may decrease the efficacy of succinylcholine because it results in a longer exposure of succinylcholineto plasma pseudocholinesterase, resulting in increased drug metabolism before the agent amves at the neuromuscular junction.40

Overall, there is no difference in the cardiovascular complication rate and mortality relating to the choice of regional or general anesthesia.56~57 There are situations in which one agent may be preferred, e.g., (1)regional anesthesia for the patient with severe pulmonary disease and left ventricular dysfunction to avoid the respiratory and cardiac depression of general anesthesia; (2) avoidance of spinal anesthesia, with its risk of vasodilation, in the patient with a fixed cardiac output; and (3) general anesthesia for the anxious patient with ischemic heart disease to avoid anxiety-related catecholamine release and provocation of angina.74The risk of local anesthesia has been studied in reference to a few surgical procedures in the elderly. In ophthalmic surgery utilizing local anesthesia in patients with prior myocardial infarction, its use has been associated with a trivial incidence of perioperative cardiac c~mplication.~ For the geriatric patient undergoing surgical repair of a groin hernia, local anesthesia has been found to be associated with lower risk of cardiovascular complication than regional or general anesthesia.44

THE PATIENT WITH ISCHEMIC HEART DISEASE Occult coronary artery disease is present in a significant number of elderly individual^.^ An autopsy study from Olmsted County, Minnesota, documented that over 60% of persons aged 60 or older were found to have 75-100% occlusions of at least one major coronary artery.15 In the elderly the clinical description of angina pectoris is often similar to that in younger patients, but dyspnea, syncope, and exertional diaphoresis are common anginal equivalent^.^^ The manifestations of acute mvocardial infarction mav differ ii the elderly in that confusion, congestive heart failure, arrhythmias; and dyspnea may be the presenting complaints instead of chest pain. The patient who is stable on a chronic antianginal regimen should be continued on that regimen until the time of surgery. It is essential that an effective antianginal regimen be maintained during and following surgery. For the patient chronically taking beta-adrenergic blocking agents, we often give a long-acting preparation (e.g., atenolol, nadolol) on the morning of surgery. This provides the patient with beta-blockade for up to 24 hours. If the chronic oral regimen cannot be reinstituted at this time, parenteral propranolol0.5-1.0 mg may be given every 4-6 hours until oral agents are resumed. This is usually done in a setting in which heart rate and rhythm can be monitored to detect any beta-blocker-induced conduction system abnormalities in the elderly patient. For the patient taking nitrates or calcium channel antagonists, we substitute with topical or intravenous nitrates, e.g., nitro1 ointment 3: to 2 inches every 8 hours or intravenous nitroglycerine 25-100 pglminute, until medications are resumed. If breakthrough angina or coronary artery spasm occurs, the nitroglycerine dose is increased or sublingual nifedipine is given. Chronic stable angina has not been found to be a risk factor for perioperative cardiac complications. This assumes, however, that the patient leads an active life and has angina that is provoked only by exertion. Therefore, evaluation of coronary artery status in this patient group is not recommended

prior to noncardiac surgery. For the patient with new onset or unstable angina, the risk of perioperative myocardial infarction is significantly increased.12 Therefore, if possible, surgery should be delayed until coronary status can be defined and a coronary revascularization procedure performed if indicated. If surgery cannot be delayed, precautions similar to those for the patient who has sustained a recent myocardial infarction shoilld be undertaken. The sedentary patient who experiences occasional episodes of angina presents a difficult assessment problem in the preoperative period. If possible, we attempt to assess coronary status with exercise stress testing prior to major noncardiac surgery and estimate need for perioperative invasive hemodynamic monitoring as well as prophylactic antianginal therapy based on the results of the exercise study. The perioperative risk to the patient who has sustained a myocardial infarction within 6 months of surgery has been described. Approximately 10%of men and 5%ofwomen over age 65 have electrocardiographic evidence of a prior myocardial infarction, with many of these persons lacking clinical features that would allow estimation of the approximate date of the infarction. When we are unable to determine whether the myocardial infarction has occurred within the preceding 6 months and surgery is to be done on a semielective basis, we perform risk stratification in a manner similar to that done for the patient who has had a recent myocardial infarction. If left ventricular function is preserved and there is no exercise electrocardiographic evidence of myocardial ischemia, we usually proceed with planned surgery. Patients found to be at higher risk, i.e., those with evidence of significant exercise induced myocardial ischemia, are often considered for coronary arteriograph~and a coronary revascularization ~rocedure,if indicated, prior to noncardiac surgery. The patient who has had successful coronary artery revascularization, i.e., coronary artery bypass surgery or percutaneous transluminal coronary angioplast~,and who has preserved left ventricular function can usually undergo general surgery with low risk of perioperative myocardial infarction. If there is question as to the patency of a previously revascularized coronary artery, an exercise electrocardiogram is often helpful to evaluate for the presence of myocardial ischemia. Most postoperative myocardial infarctions occur during the first 5 days following surgery. While the peak risk has classically been thought to be on the third to fifth postoperative da~,22,6~ recent studies indicate that the peak incidence of postoperative myocardial infarction is probably the first 24-48 hours following surgery.' Up to 61% of perioperative myocardial infarctions are not accompanied by angina pain. Common features of postoperative myocardial infarctions are acute congestive heart failure, hypotension, arrhythmias, and changes in mental status. The unexplained occurrence of any of these problems in the patient following surgery should initiate a search for the presence of an acute myocardial infarction. Electrocardiographic identification of acute myocardial infarction is difficult in the elderly because of an increased incidence of cardiac conduction abnormalities, prior myocardial infarction, and left ventricular h y p e r t r ~ p h yEnzymatic .~~ confirmation is difficult in the elderly because they tend to have smaller rises in total creatine phosphokinase (CPK), probably due to decreased muscle mass.

NONCARDIACSURGERY IN THE PATIENT WITH CARDIOVASCULAR DISEASE

519

Increases in the MB fraction of CPK are preserved in the elderly in the setting of acute myocardial infarction.28

THE PATIENT WITH VALVULAR HEART DISEASE Aortic stenosis is the most frequently found type of clinically significant valvular heart disease in the elderly. In adults who present with aortic stenosis prior to age 65, it is usually the result of scarring and calcification of a congenitally bicuspid aortic valve; whereas in those who initially present after age 65, aortic stenosis is commonly a result of calcification of a previously normal valve. As noted, the presence of aortic stenosis is a risk factor for the development of cardiac complications during or following noncardiac surgery. While the perioperative cardiac mortality rate was initially found by Goldman to be up to 13% for patients with severe aortic stenosis who underwent noncardiac surgery, there is evidence that in selected patients with modern anesthetic technique and perioperative hemodynamic monitoring this risk may be lower than initially determined.46 In the elderly, preoperative clinical identification and quantitation of aortic stenosis is often difficult. The typical systolic murmur, fourth heart sound, and left ventricular hypertrophy may be a result of causes other than aortic stenosis, whereas the patient with left ventricular dysfunction may have a marked attenuation or even absence of the murmur. Delay of the upstroke of the carotid pulse, a classic finding of aortic stenosis, may also be absent in the elderly patient due to decreased elasticity of the vascular tree.51 Therefore, Doppler echocardiography should be considered to preoperatively quantitate the degree of aortic stenosis in the patient in whom aortic stenosis is suspected. Patients with aortic stenosis often have significant abnormalities of cardiac hemodynamics which must be considered in the perioperative period. They typically have a "fixed" cardiac output owing to left ventricular outflow obstruction and may be unable to increase cardiac output in response to the stress of surgery. Therefore, they often poorly tolerate hypovolemia and vasodilation associated with spinal anesthesia or the use of vasodilating medications in the perioperative period. Decreased left ventricular compliance as a result of left ventricular hypertrophy is also a common finding. For these reasons invasive hemodynamic monitoring is often a useful aid for management of the patient's volume status during and immediately following surgery. The onset of atrial fibrillation with subsequent loss of the atrial contribution to ventricular filling may result in hypotension and/or pulmonary edema; therefore, maintenance of sinus rhythm is essential in the perioperative period. For the patient with critical aortic stenosis who requires a major surgical procedure and in whom surgical replacement of the aortic valve is not feasible, percutaneous aortic valve balloon angioplasty has been described as a technique to transiently decrease the degree of aortic stenosis and improve cardiac h e m ~ d y n a m i c s . ~ ~ Aortic insufficiency in the elderly may be chronic or acute. Chronic etiologies include hypertension, aortic valve sclerosis, endocarditis, valve

root dilatation, and rheumatic valve disease. Aortic dissection and infective endocarditis are among the most common causes of acute aortic insufficiency. Operative cardiac risk relating to noncardiac surgery correlates more with the status of left ventricular function than with the degree of valvular insufficiency.27 Perioperative factors that may increase thevdegree of regurgitation and that should be avoided include the use of vasouressor agents, ., - with subsequent increases in peripheral vascular resistance, and bradycardia, because an increase in diastolic filling time allows for a greater time period during which regurgitation may occur. Mitral stenosis in the elderlv is almost alwavs due to rheumatic valvular disease. Rarelv it mav be a result of massive mitral annulus calcifi~ation.~~ The most important parameters that relate to the risk of perioperative cardiac complication are the degree of valve stenosis, heart rate, and intravascular volume status. Left atrial pressure, elevated at baseline to maintain adequate ventricular filling, is further increased by perioperative volume overload. This may result in pulmonary edema. Tachycardia may adversely affect hemodvnamic balance because it is associated with a decreased diastolic filling time and therefore decreased transit time across the mitral valve. Intravascular volume depletion may significantly decrease left atrial volume, resulting in inadequate filling of the left ventricle and decreased cardiac output. Because of their often fragile hemodynamic status, the use of invasive hemodynamic monitoring should be considered for patients with severe mitral stenosis who undergo surgical procedures during which significant intravascular volume shifts are antici~ated. Mitral reeurgitation mav be a result of a defect in one or more components of the mitral valve apparatus, e.g., valve annulus, chordae, papillary muscles, left ventricular wall. In the elderly the most common causes of mitral regurgitation are ischemic heart disease, left ventricular dilatation, mitral valve prolapse, and mitral annular calcification. In the setting of mitral regurgitation, the left ventricle is "afterload reduced" because blood is ejected into the low pressure left atrium as well as into the systemic circulation. For this reason ejection fraction in the patient with normal left ventricular function should be greater than normal. An ejection fraction that is even slightly abnormal in the patient with significant mitral regurgitation implies the presence of left ventricular dysfunction. The patient with significant mitral regurgitation and left ventricular dvsfunction should have " " invasive hemodynamic monitoring in the perioperative period if significant shifts of intravascular volume are anticipated. Hypertrophic obstructive cardiomyopathy is not uncommon in the elderly and may be asymptomatic and detected when an echocardiogram is done for an unrelated reason.58A variant is hypertensive hypertrophic cardiomyopathy of the elderly in which the patient has a history ofhypertension, chest pain or dyspnea, and severe left ventricular hypertrophy with supernormal left ventricular function.68The major hemodynamic abnormality for these patients is left ventricular diastolic dysfunction. In the perioperative period, factors that can lead to hemodynamic instability are drugs that further increase left ventricular contractility and worsen diastolic dysfunction (catecholamines) and reduction of left ventricular preload with subsequent impairment of left ventricular filling (hypovolemia, vasodilation, spinal anes-

-

L,

NONCARDIAC SURGERY IN THE PATIENT WITH CARDIOVASCULAR DISEASE

521

thesia).65 Invasive hemodynamic monitoring should be utilized in the patient in whom significant perioperative volume changes are anticipated. Perioperative hypotension should initially be treated with intravascular volume administration. If that is unsuccessful, peripheral vasoconstriction with alpha agonists, e.g., phenylephrine hydrochloride, is often helpful in raising systemic blood pressure. Management of anticoagulation for the patient with a prosthetic heart valve presents a challenge in the perioperative period. For most mechanical prosthetic valves, anticoagulation may be discontinued an average of 2.9 days before surgery and restarted 2.7 days postoperatively without risk of thromboembolic complication.67In patients with caged-disk prosthetic mitral valves a small incidence of thromboembolic complication has been observed when anticoagulation is withheld.31 Based on these findings we recommend that for most patients oral anticoagulants be discontinued 2 days before surgery and that surgery be performed if prothrombin time has dropped to within 2 seconds of the control value. Anticoagulation with intravenous heparin should be started within 24 hours of surgery once hemostasis is stable and oral anticoagulants restarted when oral intake resumes. For patients with caged-disk mitral valves, we suggest that they be admitted to the hospital 2 days before surgery, at which time oral anticoagulants are stopped and full anticoagulation with intravenous heparin is begun. Heparin is discontinued 8-12 hours before surgery and restarted as soon as hemostasis is achieved following surgery. Oral anticoagulation is begun when the patient is able to tolerate oral medications. Infective endocarditis antibiotic prophylaxis is recommended for the patient with a prosthetic valve who is to undergo a surgical procedure associated with the risk of bacteremia (Table 4). There is no consensus as to whether the elderly patient with aortic sclerosis without aortic stenosis or mitral annulus calcification without mitral regurgitation requires antibiotic infective endocarditis prophylaxis.51 THE PATIENT WITH CONGESTIVE HEART FAILURE

The incidence of heart failure increases dramatically with advancing age starting in the fifth decade of life.39The most common etiology is systolic ventricular dysfunction due to ischemic heart disease or hypertension. Other causes of congestive heart failure in the elderly are arrhythmias; conduction abnormalities; valvular heart disease, particularly aortic stenosis; anemia; infection; thyroid disease; and concomitant medications, e. g., nonsteroidal anti-inflammatorv medications with resultant sodium retention and beta or calcium channel antagonists with myocardial depressi0n.~5The elderly also have a high incidence of diastolic ventricular dysfunction as a result of increased myocardial stiffness as well as an age-related prolongation of ventricular relaxation time. l3 The incidence of perioperative pulmonary edema in relation to major noncardiac surgery in patients over age 40 ranges from 3% in patients with New York Heart Association (NYHA) class I symptoms to 25% in those patients with NYHA class IV symptoms. Fifty to 60%of patients who develop

Table 4 . lnfective Endocarditis Prophylaxis Dental procedures, respiratory procedures Standard regimen

Penicillin V 2 gm PO 1 hour before procedure and penicillin V 1 gm PO 6 hours later or Penicillin G 2 million units IV or IM 30-60 minutes before procedure and penicillin G 1 million units IV or IM 6 hours later Erythromycin 1 gm PO 1 hour before proceStandard regimen (allergic to penicillin) dure and 500 mg PO 6 hours after initial dose Ampicillin 1-2 gm IM or IV and gentamicin Higher risk regimen (prosthetic valve) 1.5 mg/kg IM or IV 30 minutes before procedure; then penicillin V 1.0 gm PO 6 hours after initial dose Vancomycin 1 gm IV over 60 minutes, begun Higher risk regimen (allergic to penicillin) 60 minutes before procedure; no repeat dose necessary Gastrointestinal and genitourinary tract surgery and instrumentation Ampicillin 2 gm IM or IV plus gentamicin Standard regimen 1.5 mgfkg given 30 minutes before procedure; repeat dose 8 hours after initial dose Vancomycin 1 gm IV given over 60 minutes Regimen for penicillin-allergic patients plus gentamicin 1.5 mgkg IM or IV, each given 60 minutes before procedure; repeat dose 8 hours after initial dose Amoxicillin 3 gm 1 hour before procedure Oral regimen for low-risk patients and 1.5 Em 6 hours after initial dose -

-

-

From A statement for health care professionals by the Committee on Rheumatic Fever and Infective Endocarditis: Prevention of bacterial endocarditis. Circulation 70:1123A-1127A. 1984; with permission of the American Heart Association.

perioperative pulmonary edema have no prior signs or symptoms to suggest this complication. Advanced age is a risk factor for development of perioperative pulmonary edema. Other risk factors include prior history of perioperative pulmonary edema, abnormal preoperative electrocardiogram, and intraabdominal or intrathoracic surgery.23Seventy per cent of patients who develop postoperative pulmonary edema do so within the first hour following termination of anesthesia, with the majority during the first 30 minute^.^ Whereas the majority of cases are due to intraoperative fluid overload, other contributing factors include anesthesia-induced myocardial depression, cessation of positive pressure ventilation, and postoperative hypertension. Patients who are well maintained on an oral medical regimen should have their medications continued up to the time of surgery. For the patient who is unable to resume oral medications following surgery, a parenteral regimen should be substituted. Management of the patient at high risk for development of pulmonary edema is often aided with the use of invasive hemodynamic monitoring.

PERIOPERATIVE ARRHYTHMIAS AND CONDUCTION ABNORMALITIES Asymptomatic supraventricular and ventricular arrhythmias are common in the healthy elderly population.16They are also common during an-

NONCARDIACSURGERY IN THE PATIENT WITH CARDIOVASCULAR DISEASE

523

esthesia and surgery, with between 62% and 84% of patients developing arrhythmias in the perioperative period.34.38 Most surgically related arrhythmias are supraventricular and include wandering atrial pacemaker, isorhythmic A-V dissociation, nodal rhythm, and sinus bradycardia. Factors that provoke arrhythmias in the perioperative period include hypoxia, hypercarbia, hypokalemia, hyperkalemia, and alteration of autonomic tone, e.g., occular or visceral traction. In most cases correction of these factors will lead to resolution of the arrhvthmia.32 The risk for development of'supraventricular arrhythmias during surgery has been studied by G ~ l d r n a nAge . ~ ~ greater than 70 is a risk factor. Other risk factors are the presence of preoperative rales and intraabdominal, intrathoracic, or major vascular surgery. When supraventricular tachycardia leads to hemodynamic instability, DC cardioversion should be performed. When there is no evidence of hemodynamic compromise, medical therapy is utilized in an effort to slow the ventricular rate andlor to restore sinus rhythm. Parenteral medications used in the perioperative period to achieve this include digoxin, propranolol, esmolol, verapamil, and adenosine. Because atrial flutter is often difficult to convert to sinus rhythm with medical therapy, low-energy cardioversion (25-50 joules) or rapid atrial pacing is often the most effective techniaue to restore sinus rhvthm. The significance and management of ventricular arrhythmias in the elderly are similar to those in the younger patient. While greater than five ventricular premature contractions per minute is a risk factor for the development of perioperative cardiac complications, this risk is probably a result of underlying heart disease. Because ventricular ectopy may therefore be an indicator of underlying heart disease, the role of arrhythmia suppression without correction of coexistent heart disease ~ r i oto r surgerv is limited. " We recommend that perioperative prophylactic antiarrhythmics be utilized for the patient who has a history of significant symptomatic ventricular arrhythmias, sustained ventricular tachycardia, or sudden cardiac death. Hemodynamically significant ventricular arrhythmias that occur during surgery are treated with intravenous lidocaine or procainamide while searching for a reversible etiology, e.g., hypoxia, hypercarbia, electrolyte abnormality. Antiarrhythmic clearance may be impaired in the elderly patient in the perioperative period. Procainamide clearance is delayed in the elderly and is further impaired in the presence of renal dysfunction, whereas lidocaine metabolism is impaired in the presence of hepatic dysfunction or congestion or if there is anesthetic-induced decrease in cardiac output. Lidocaine central nervous system toxicity characterized by confusion,-delirium, stupor, or coma is increased in the elderly.36Finally, antiarrhythmics may be proarrhythmic in up to 11% of casesU7O ~ m ~ a i r m e noft sinus and atrioventricular node function normally accompanies advanced age. The incidence of fascicular block also increases with age and may be present in up to 10% of the elderly.42 Sick sinus syndrome characterized by a variety of abnormalities of sinus node function, e.g., unexplained persistent sinus bradycardia, sinus arrest, sinus bradycardia, or sinus arrest with paroxysmal atrial tachycardia (bradycardia-tachycardia syndrome) as well as trifascicular block is almost always limited to the elderly.72During surgery sinus bradycardia is common and is usually due to ---

2

-

2

~

-

Table 5. Indications for Implantation of Cardiac Pacemukers 1. Complete heart block (permanent or intermittent) associated with:

2. 3.

4. 5. 6.

Symptomatic bradycardia Congestive heart failure Arrhythmia requiring drugs that will suppress escape rhythm Documented asystole 2 3 . 0 sec or escape rate <40 bpm Second degree A-V hlock with symptomatic bradycardia Bifascicular block with intermittent complete heart block with symptomatic bradycardia Symptomatic bifascicular block with intermittent Type I1 second-degree A-V block Sinus node dysfunction with documented symptomatic bradycardia Persistent, advanced second-degree A-V block or complete heart block following acute myocardial infarction

Adapted from Frye R, Collins JJ, DeSanctis RW, et al: Guidelines for permanent pacemaker implantation. Circulation 70:331A-339A, 1984; with permission of the American Heart Association.

alterations in autonomic tone. If associated with hemodynamic impairment, it should be treated with intravenous atropine. Acute perioperative advanced heart block is rare during surgery. In a total of 305 patients (mean age 70) with chronic bifascicular block observed in six studies, only one patient developed acute complete heart block during surgery. This was transient and occurred during endotracheal int~bation.4,5,'9,35.~,~~ For this reason insertion of a prophylactic temporary transvenous pacemaker is not recommended in the elderly patient with chronic bifascicular block who is to undergo general surgery. A possible exception would be the patient with chronic left bundle branch block who is to undergo placement of a pulmonary artery Swan-Ganz catheter. This procedure is associated with an up to 5% incidence of transient right bundle branch block which, when associated with left bundle branch block, results in complete heart For this reason, a method for ventricular pacing should be available if complete heart block occurs during pulmonary artery catheter placement in this patient group. A temporary pacemaker should be inserted prior to surgery if the patient meets the criteria for permanent pacemaker implantation and the pacing device has not yet been implanted (Table 5). The patient with a permanent pacemaker should have the pacemaker tested both before and after surgery. The most significant pacemaker problem in relation to general surgery is pacemaker inhibition due to electrocauteryinduced electromagnetic interference. Because there is no industry-wide standardized response to electromagnetic interference, it is important that these data be obtained from the pacemaker manufacturer prior to surgery.59 Most W I pacemakers will be inhibited by electromagnetic interference. This may be avoided by programming the pacemaker to a fixed rate mode or by placing a magnet over the pacemaker generator, causing it to pace at a fixed rate. Other precautionary measures include placing the electrocautery ground plate as far away from the pacemaker as possible, avoiding cautery in the vicinity of the pacemaker generator and lead, and limiting the frequency and duration of electrocautery to no more than 1-second bursts at least 10 seconds apart.60

THE PATIENT WITH HYPERTENSION The prevalence of hypertension (blood pressure r 160 mm Hg systolic andlor 95 mm Hg diastolic) approaches 50% in the elderly76 While the impact of systolic hypertension on the incidence of perioperative cardiac complications is unknown, diastolic hypertension greater than 110 mm Hg is a risk for development of myocardial ischemia, myocardial infarction, pulmonary edema, and arrhythmias in the perioperative period.21Prior to surgery, the patient with hypertension should be evaluated for the presence of end organ damage, e.g., renal dysfunction, hypertensive retinopathy, and myocardial ischemia. While more than 90% of elderly hypertensives have essential hypertension, a small percentage have a secondary etiology. The presence of renal artery stenosis as a cause of hypertension should be considered prior to surgery because elderly patients with renovascular hypertension have great lability of blood pressure in the perioperative period. Clues to the presence of renovascular hypertension include new-onset hypertension in the elderly patient, worsening of previously controlled hypertension, and hypertension that is refractory to an aggressive antihypertensive drug regimen. Diuretics are one of the most commonly used antihypertensive agents in the elderly and in low doses are often well t ~ l e r a t e dPrior . ~ ~ to surgery, patients taking diuretics should be evaluated for the presence of intravascular volume depletion. This may be done by observing for orthostatic changes in blood pressure. Serum potassium levels should also be measured. If present, these abnormalities should be corrected prior to surgery because intravascular volume depletion may contribute to anesthetic-induced hypotension, and abnormal potassium levels may result in perioperative cardiac arrhythmias. Whereas centrally acting antihypertensive agents, angiotensin converting enzyme inhibitors, calcium channel antagonists, and beta-blockers are utilized in the elderly, it is sometimes difficult to find an appropriate parenteral agent to maintain blood pressure control when the patient is unable to tolerate oral medications. Methyldopa is often well tolerated and can be given intravenously. Its onset of action is 30-60 minutes, with a duration of action up to 6 hours. For the patient who requires angiotensin converting enzyme inhibitors, enalapril is available as an intravenous preparation. A suitable parenteral calcium channel antagonist is not yet available. Sublingual nifedipine has been used for the treatment of perioperative hypertension in elderly patients undergoing ophthalmologic surgery2It should be used cautiously to avoid precipitation of hypotension and tachycardia. For the patient who is chronically treated with oral beta-blockers, intravenous propranolol may be given in a manner similar to that for the patient who is receiving beta-blockers for the treatment of angina. A cautious approach should be taken for the treatment of postoperative hypertension. In the elderly, too rapid a decrease in blood pressure may lead to cerebral hypoperfusion and/ or myocardial ischemia. Initially the common precipitating causes of perioperative hypertension should be searched for and corrected. They include pain, hypoxia, hypercarbia, hypothermia, and fluid overload. If hypertension persists significantly above the patient's preoperative baseline or if hyper-

tension is associated with cerebral or myocardial ischemia, then parenteral antihypertensive therapy should be given."

THE PATIENT WITH PERIPHERAL VASCULAR DISEASE Myocardial ischemia and infarction are the leading causes of morbidity and mortality following peripheral vascular surgery. In a study of 1000 patients, mean age 64, referred for surgical repair of aortic aneurysm, lower extremity vascular insufficiency, and carotid artery disease, Hertzer found that 92% of patients had coronary artery disease, with approximately 30% of the total group with coronary artery disease that either warranted surgical revascularization or was inoperable.25 Many of these patients were asymptomatic. Various approaches have been recommended to identify the patient with significant coronary artery disease prior to surgery who might benefit from coronary arteriography and revascularization, if indicated, prior to the peripheral vascular surgical procedure. A positive exercise electrocardiogram strongly suggests significant coronary artery disease and an increased risk of cardiac complication during vascular surgery, but many of these patients are unable to perform the required treadmill exercise.ll Dipyridamole-thallium scanning has been shown to be sensitive for the presence of coronary artery disease and is safe in the elderly. Recently Eagle et a1 have advocated that clinical variables be used to determine the need for dipyridamole-thallium scanning in the preoperative risk stratification of patients prior to vascular surgery.14 They found that clinical variables that increase the perioperative cardiac risk of vascular surgery are evidence of a prior Q wave myocardial infarction on the electrocardiogram, history of ventricular ectopy requiring treatment, diabetes requiring treatment, history of angina, and age greater than 70.14 The patient with none of these variables has been shown to have a low incidence of perioperative cardiac complications (3.2%) and in most cases does not require preoperative evaluation of coronary status. The patient with three or more variables has a high (50%) incidence of perioperative cardiac complications and will often require coronary arteriography with coronary artery revascularization, if indicated, prior to vascular surgery. For the patient at intermediate risk, i.e., one or two variables, which would include the patient over age 70. the result of dipyridamole-thallium scanning aids in the cardiac risk determination. In this group evidence of dipyridamole-induced myocardial ischemia indicates approximately a 30% risk of cardiac complication. Absence of myocardial ischemia predicts only a 3.2% risk. Therefore, the patient in this intermediate risk group with dypyridamole-thallium-induced evidence of myocardial ischemia should be considered for coronary arteriography to determine the need for coronary revascularization prior to peripheral vascular surgery. In contrast, the patient with no evidence of dypyridamole-thallium-induced myocardial ischemia could then proceed to planned peripheral vascular surgery. l4 Asymptomatic carotid bruits are common in the elderly, with one study of persons aged 75 or older indicating a prevalence of 12%.69The patient

1

l

1 1

with an asymptomatic carotid bruit is not at increased risk of sustaining a postoperative stroke following noncardiac surgery."

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Howard H. Weitz, MD Division of Cardiology and Internal Medicine Jefferson Medical College 111 South 11th 'street Philadelphia, PA 19107-5092