Download Preoperative Evaluation of the Patient With Hypertension

CONTEMPO UPDATES
LINKING EVIDENCE AND EXPERIENCE
Preoperative Evaluation of the Patient
With Hypertension
Lee A. Fleisher, MD
H
YPERTENSION, ONE OF THE MOST
common diagnoses in the US
adult population, has prevalence in excess of 50% of individuals
older than 65 years.1 Approximately 23
million US patients are anesthetized annually2; they commonly present for preoperative evaluation to the primary care
physician, consultant, surgeon, or anesthesiologist with either diagnosed or
undiagnosed hypertension. Even if a patient carries the diagnosis of hypertension and takes antihypertensive therapy,
the hypertension may be poorly controlled. Additionally, long-standing hypertension may result in end-organ damage in the heart, brain, and kidneys,
which might be unrecognized until the
time of the preoperative evaluation. Accordingly, the preoperative evaluation is
a unique opportunity to identify patients with hypertension and evaluate
them for appropriateness of therapy and
the presence of end-organ damage. Given
the current pressures to proceed expeditiously with scheduled surgery, it is important for the physicians evaluating
such patients to understand the evidence regarding the value of delaying surgery and instituting additional pharmacologic therapies to reduce perioperative
and long-term adverse outcomes.
Outcomes of Interest
A wide range of outcomes in patients
with hypertension have been studied.
While hypertension can affect the brain
and kidneys, the vast majority of the
perioperative literature has focused on
the cardiovascular system. For most cardiovascular interventions, the primary
end points studied have been myocardial infarction (MI) and death. However, many of these trials were underpowered to detect those outcomes.
Investigators have evaluated the relationship between hypertension and
surrogate outcomes such as blood pressure (BP) lability and electrocardiographic changes indicative of ischemia
as the primary outcomes of interest. The
rationale for inclusion of these outcomes is that they are on the continuum to the development of perioperative cardiac morbidity. Several studies
have demonstrated a significant relationship between the occurrence of perioperative myocardial ischemia and fatal and nonfatal MI, with the occurrence
of prolonged ischemia identifying those
patients at greatest risk.3-5 The vast majority of patients who demonstrate perioperative myocardial ischemia will have
an uncomplicated perioperative course,
suggesting that suppression of myocardial ischemia alone does not necessarily correlate with a reduced incidence of
MI or death.3 Some investigations have
used hemodynamic parameters; however, hypotension or BP lability has not
been shown to be a significant predictor of myocardial ischemia or infarction.6 The strongest available evidence
correlates the effect of interventions on
the rate of perioperative MIs and death,
and not surrogate outcomes.
Perioperative Cardiovascular
Complications
Mild to moderate hypertension (stage 1
or stage 2 hypertension) affects patients
with systolic BP below 180 mm Hg and
diastolic BP below 110 mm Hg. The evidence suggests that these patients do not
appear to be at increased operative risk
for cardiovascular adverse outcomes.
In 1979, Goldman and Caldera7 studied 196 patients with hypertension (79
adequately treated, 40 inadequately
treated, and 77 untreated) and observed
no difference in perioperative outcome. Several large-scale trials of con-
©2002 American Medical Association. All rights reserved.
secutive adult patients undergoing noncardiac surgery were not able to identify
hypertension as a predictor of cardiovascular complications.8,9
There are several issues in interpreting these results. These studies acknowledge the absence of patients with
diastolic BPs of more than 110 mm Hg,
limiting the generalizability of their
findings to the population with poorly
controlled hypertension. The diagnosis of hypertension may have triggered an evaluation for occult coronary artery disease, whose presence
would then negate the original impact
of hypertension alone in these multivariate models. For example, the presence of new Q waves on an electrocardiogram would have triggered further
diagnostic testing. It is therefore important as part of the preoperative
evaluation to distinguish whether the
patient has isolated hypertension or also
has coexisting coronary artery disease. For those with isolated mild to
moderate hypertension, the current recommendation is that it is appropriate
to proceed to surgery without delay or
escalation in medical therapy.10
For patients with severe hypertension (stage 3, systolic BP ⬎180 mm Hg
and diastolic BP ⬎110 mm Hg), many
physicians and investigators believe that
BP should be controlled prior to proceeding to elective noncardiac surAuthor Affiliation: Department of Anesthesiology,
Joint Appointments in Biomedical Information
Sciences, Medicine, and Health Policy and Management, Johns Hopkins University School of Medicine,
Baltimore, Md.
Financial Disclosure: Dr Fleisher has received honoraria and grant support from Baxter Pharmaceuticals.
Corresponding Author and Reprints: Lee A. Fleisher,
MD, Department of Anesthesiology, Joint Appointments in Biomedical Information Sciences, Medicine,
and Health Policy and Management, Johns Hopkins
University School of Medicine, 600 N Wolfe St, Carnegie 280, Baltimore, MD 21287 (e-mail: lfleishe@jhmi
.edu).
Contempo Updates Section Editor: Janet M. Torpy,
MD, Fishbein Fellow.
(Reprinted) JAMA, April 24, 2002—Vol 287, No. 16
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2043
PREOPERATIVE EVALUATION OF HYPERTENSION
Box. Hypertensive Comorbidities Associated
With Adverse Perioperative Outcomes
Occult coronary artery disease (Q waves on the electrocardiogram)
Congestive heart failure
Left ventricular hypertrophy (voltage criteria)
Renal insufficiency (serum creatinine level ⬎2.0 mg/dL [⬎176.8 µmol/L])
Cerebrovascular disease (history of cerebrovascular accident or transient
ischemic attack)
gery.10,11 However, these recommendations have been based upon studies with
small sample sizes with outcomes other
than fatal or nonfatal MIs. In Goldman and Caldera’s study7 of 196 patients with hypertension, there were
only 5 patients with a diastolic BP of
more than 111 mm Hg. Although this
group of patients had an increased incidence of hypertensive episodes, there
was no increase in perioperative MI or
death.7 In contrast, Prys-Roberts et al12
performed a series of studies in the
1970s on small groups of patients with
hypertension and documented increased hemodynamic lability, arrhythmias, and myocardial ischemia in patients whose preoperative diastolic BP
was more than 110 mm Hg.
In the face of conflicting evidence, the
sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood
Pressure (JNC-VI) recommends delay
of surgery when the preoperative diastolic BP exceeds 110 mm Hg.13 In such
patients, BP should be reduced slowly
for fear of increasing morbidity and
mortality secondary to a critical coronary or carotid arterial stenosis. The period of time required to adequately correct the hypertension is unknown,
though amelioration of some of the
myocardial and vascular changes related to severe hypertension may require a minimum of 6 to 8 weeks of
therapy to reverse.11 The decision to delay surgery for long-term stabilization
of BP, vs acutely correcting the hypertension, must take into account the potential benefits and the urgency of the
surgical procedure.
Isolated systolic hypertension (systolic BP ⬎160 mm Hg and diastolic BP
⬍90 mm Hg) has been identified as a
risk factor for cardiovascular complications in the general population and
treatment reduces the future risk of
stroke.14 However, there has been only
one study to directly assess the relationship between cardiovascular disease and preoperative isolated systolic
hypertension. In a multicenter study of
patients undergoing coronary artery bypass grafting, the presence of isolated
systolic hypertension was associated
with a 30% increased incidence of cardiovascular complications compared
with individuals who were normotensive.15 Since it is unknown if these findings may be generalized to the noncardiac surgical population and whether
treatment will impact outcome, further study is required.
End-Organ Damage
and Perioperative Outcome
Hypertension has been associated with
the development of occult and symptomatic cardiac, cerebrovascular, and
renal disease (BOX). Patients with hypertension may have had a silent MI,
evidenced by the presence of Q waves
on the electrocardiogram.16 Congestive heart failure may occur secondary
to hypertension-induced systolic and
diastolic dysfunction. The presence of
either of these risk factors places the patient at moderate- to high-clinical risk
for perioperative MI or death; guidelines for diagnostic testing have recently been released by the American
Heart Association and the American
College of Cardiology.10
2044 JAMA, April 24, 2002—Vol 287, No. 16 (Reprinted)
In the absence of overt coronary artery disease, the presence of left ventricular hypertrophy defines the subset
of ambulatory patients with an increased risk of cardiovascular complications. In a study of patients undergoing
major vascular surgery, voltage criteria
for left ventricular hypertrophy and STsegment depression of more than 0.5 mm
on preoperative electrocardiograms were
both significantly associated with postoperative MI or cardiac death (odds ratio, 4.2 and 4.7; P=.001 and P⬍.001,
respectively).17 Hollenberg et al18 studied a consecutive sample of 474 men at
high risk for or with coronary artery disease who were scheduled to undergo major noncardiac surgery and demonstrated that hypertension and left
ventricular hypertrophy were associated with an increased incidence of perioperative myocardial ischemia. Myocardial ischemia can result in patients with
ventricular hypertrophy from supply and
demand mismatches even in the absence of coronary artery stenoses; this
supports better control of hypertension
in these patients.
Chronic renal insufficiency is a common sequela of hypertension. Patients
with hypertension should have a measurement of baseline serum creatinine. In the original Cardiac Risk Index, an elevated serum creatinine level
(⬎3.0 mg/dL [⬎265.2 µmol/L]) was
one of the independent risk factors for
perioperative cardiovascular morbidity and mortality.8 This has been confirmed in the revised Cardiac Risk Index, in which a preoperative serum
creatinine level greater than 2.0 mg/dL
(⬎176.8 µmol/L) was 1 of 6 independent factors that predicted increased
cardiovascular risk.9
Hypertension is also a risk factor for
cerebrovascular disease. Several studies have demonstrated the association
between a preoperative history of a cerebrovascular accident and the occurrence of perioperative cardiac events.9,19
While acute hypertensive crises can lead
to a stroke from an intracerebral bleed,
abrupt decreases in BP can lead to injury from cerebral ischemia. It is therefore prudent to establish norm levels for
©2002 American Medical Association. All rights reserved.
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PREOPERATIVE EVALUATION OF HYPERTENSION
maintenance of BP in a patient with hypertension and document that lowering BP in a patient with poorly controlled hypertension does not result in
neurologic changes.
Should Preoperative Cardiac
Testing Be Performed?
The American College of Cardiology
and American Heart Association have
recently updated their Guidelines on
Perioperative Cardiovascular Evaluation for Noncardiac Surgery.10 The
Guidelines advocate integration of
clinical risk factors, the patient’s exercise capacity, and surgical risk in the
decision to perform further diagnostic
testing. Based upon the information
described, hypertension is considered
a minor risk factor. Isolated hypertension should trigger a discussion of the
value of preoperative cardiac testing
only in patients undergoing high-risk
procedures such as major vascular
surgery.
Based upon the high incidence of endorgan damage, patients with hypertension should have a preoperative electrocardiogram and measurement of serum
creatinine level. If the electrocardiogram demonstrates Q waves indicative
of a silent MI or the preoperative serum
creatinine level is greater than 2.0 g/dL
(⬎176.8 µmol/L), then this constellation of risk factors would place the patient at moderate clinical risk. If this patient also has a poor exercise tolerance
and is undergoing high- or intermediaterisk (eg, abdominal or thoracic) surgery, then preoperative testing should
also be considered, but only be performed if the results will impact on the
patient’s care. Testing is indicated if the
results might lead to coronary revascularization, changes in perioperative monitoring, or medical management.
Treatment of Hypertension
As a general rule, antihypertensive
medications should be continued until the day of surgery. The hazards of
withdrawal of antihypertensive medications have been known since the
1970s. Abrupt discontinuation of
␤-blockers has been associated with
perioperative tachycardia. 20 Withdrawal of clonidine has been associated with rebound hypertension.
One class of agents may present problems during the perioperative period.
Continuation of angiotensin-converting enzyme inhibitors through the
morning of surgery has been associated with hypotension requiring vasopressor therapy after induction of
general anesthesia.21 Bertrand et al22 performed a randomized controlled trial
of continuation or discontinuation of
angiotensin II inhibitors in patients
chronically treated with these agents
and reported more frequent and severe hypotension in the group who continued the drugs. Those authors suggest that angiotensin II inhibitors
should be held the morning of surgery
and parenteral antihypertensive agents
may be given intraoperatively, if needed.
Garlic, often used by patients who
wish to decrease their BP without taking prescription medications, has anticoagulant properties that need consideration in the face of surgical
procedures.23 Patients should be queried about any over-the-counter products they ingest and given appropriate
advice on their discontinuation before
procedures.24
With regard to the optimal treatment
of the patient with poorly or uncontrolled hypertension during the preoperative evaluation, recent Guidelines and
the JNC-VI suggest that the best treatment may be cardioselective ␤-blocker
therapy.10,13 An expanding body of evidence suggests that perioperative ␤-adrenergic blockade administration improves cardiac outcomes following
noncardiac surgery. An unblinded study
of a single small dose of ␤-adrenergic
blocking agents in untreated patients
with hypertension found significantly
fewer episodes of myocardial ischemia
in the patients treated with ␤-adrenergic blocking agents vs controls.25 The
strongest evidence for ␤-blocker therapy
comes from high-risk cardiac patients;
there is limited information about patients with hypertension who do not have
known coexisting disease. In a randomized controlled trial of patients under-
©2002 American Medical Association. All rights reserved.
going major noncardiac surgery, atenolol was administered intravenously or
orally the morning of surgery, continued for 7 days postoperatively, and was
associated with a significantly lower incidence of perioperative ischemia compared with placebo.26 No difference in
perioperative MI or cardiac death was
noted in this study of 200 patients but a
significantly improved 6-month eventfree survival was found following atenolol administration. More recently, Poldermans et al27 studied the perioperative
use of bisoprolol in elective major vascular surgery. Patients received their
medication for at least 7 days preoperatively, titrated to achieve a resting heart
rate of less than 60/min, and continued
postoperatively for 30 days. Among
patients with at least one clinical risk factor and a positive dobutamine echocardiogram, bisoprolol led to an approximate 80% decrease in perioperative
MI or cardiac death in this high-risk
population.
Intraoperative and postoperative
treatment of hypertension can be
achieved with multiple agents. Since
several days may lapse before oral intake is resumed, parenteral treatment
with diuretics, adrenergic inhibitors,
vasodilators, angiotensin-converting enzyme inhibitors, or use of transdermal
clonidine have all been proposed in the
JNC-VI.13 It is critical to initiate some
form of therapy to prevent rebound hypertension and tachycardia observed
from withdrawal of these agents.
Conclusion
The strength of evidence suggests that the
patient with stage 1 or 2 hypertension
and no evidence of end-organ damage or
coexisiting cardiovascular disease may
safely proceed to surgery without escalation of therapy. For those patients with
stage 3 hypertension (diastolic pressure ⬎110 mm Hg), there is insufficient evidence to determine the approach leading to the best outcome,
though some authors have suggested that
postponement of elective surgery for 6
to 8 weeks of antihypertensive therapy
may allow regression of some of the vascular changes associated with hyperten-
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2045
PREOPERATIVE EVALUATION OF HYPERTENSION
sion.11 This practice must be balanced
against the urgency of the surgery and
acknowledgment of the lack of data to
determine if such practices will improve outcome. At a minimum, medications should be initiated or titrated preoperatively to achieve more normal BP
prior to undergoing surgery, acknowledging that too rapid or too extreme lowering of BP may put the cerebral or other
circulations at risk for ischemia. Particularly in the subset of patients with known
coronary artery disease or undergoing
vascular surgery, ␤-adrenergic blocking agents may be effective in reducing
cardiovascular complications. If sufficient time exists (minimum 7 days), titration of ␤-blocking agents to a resting
heart rate of 60/min should be the goal.
For more acute preoperative administration (⬍7 days), additional ␤-blocker
medications can be given preoperatively and intraoperatively and incorporated into the anesthetic plan.
In many patients, hypertension is associated with coronary artery disease,
left ventricular hypertrophy, chronic renal insufficiency, and cerebrovascular
disease, which may not have been identified prior to the preoperative evaluation. For these patients, additional interventions, including cardiovascular
testing, should be contemplated to reduce perioperative risk of adverse outcomes. By using the preoperative evaluation as an opportunity to evaluate and
intervene in patients with hypertension, perioperative and long-term outcomes may be improved.
ation for noncardiac surgery—executive summary: a
report of the American College of Cardiology/
American Heart Association Task Force on Practice
Guidelines (Committee to Update the 1996 Guidelines on Perioperative Cardiovascular Evaluation for
Noncardiac Surgery). J Am Coll Cardiol. 2002;39:
542-553.
11. Prys-Roberts C. Isolated systolic hypertension:
pressure on the anaesthetist? Anaesthesia. 2001;56:
505-510.
12. Prys-Roberts C, Meloche R, Foex P. Studies of anaesthesia in relation to hypertension: cardiovascular
responses to treated and untreated patients. Br J Anaesth. 1971;43:122-137.
13. The sixth report of the Joint National Committee
on Prevention, Detection, Evaluation, and Treatment
of High Blood Pressure. Arch Intern Med. 1997;157:
2413-2446.
14. Prevention of stroke by antihypertensive drug treatment in older persons with isolated systolic hypertension: final results of the Systolic Hypertension in the Elderly Program (SHEP). JAMA. 1991;265:3255-3264.
15. Aronson S, Boisvert D, for Multicenter Study of
Perioperative Ischemia. The relationship between isolated preoperative systolic hypertension and perioperative and postoperative cardiovascular outcomes.
Anesth Analg. 2001;92:S45.
16. Kannel W, Abbott R. Incidence and prognosis of
unrecognized myocardial infarction: an update on the
Framingham Study. N Engl J Med. 1984;311:11441147.
17. Landesberg G, Einav S, Christopherson R, et al.
Perioperative ischemia and cardiac complications in major vascular surgery: importance of the preoperative
twelve-lead electrocardiogram. J Vasc Surg. 1997;26:
570-578.
18. Hollenberg M, Mangano DT, Browner WS, et al.
Predictors of postoperative myocardial ischemia in patients undergoing noncardiac surgery. JAMA. 1992;
268:205-209.
19. Boersma E, Poldermans D, Bax JJ, et al. Predictors
of cardiac events after major vascular surgery: role of
clinical characteristics, dobutamine echocardiography,
and ␤-blocker therapy. JAMA. 2001;285:1865-1873.
20. Prys-Roberts C, Foex P, Biro GP, Roberts JG. Studies of anaesthesia in relation to hypertension: adrenergic beta-receptor blockade. Br J Anaesth. 1973;45:
671-681.
21. Coriat P, Richer C, Douraki T, et al. Influence of
chronic angiotensin-converting enzyme inhibition on
anesthetic induction. Anesthesiology. 1994;81:299307.
22. Bertrand M, Godet G, Meersschaert K, et al. Should
the angiotensin II antagonists be discontinued before surgery? Anesth Analg. 2001;92:26-30.
23. Jonas WB, Levin JS, eds. Essentials of Complementary and Alternative Medicine. Baltimore, Md: Williams & Wilkins; 1999:118-363.
24. Ang-Lee MK, Moss J, Yuan CS. Herbal medicines and perioperative care. JAMA. 2001;286:208216.
25. Stone JG, Foex P, Sear JW, et al. Myocardial ischemia in untreated hypertensive patients: effect of
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26. Wallace A, Layug B, Tateo I, et al. Prophylactic
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2046 JAMA, April 24, 2002—Vol 287, No. 16 (Reprinted)
©2002 American Medical Association. All rights reserved.
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