Anaesthesia and ihd

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Weekly SCIENTIFIC Seminar

ORGANIZED BY
DEPARTMENT OF
ANAESTHESIOLOGY
SBMCH,BARISAL

Anaesthesia for Noncardiac
surgery in patient with IHD

DR. MIZANUR RAHMAN
Anaesthesiologist
Department of Anaesthesia
Sher-E-Bangla Medical
College Hospital, Barisal

Overview
 Leading cause of death & health care expenditure
5% of patients over 35 years of age have asymptomatic
ischaemic heart disease
Major cause of morbidity & loss of productivity
 May be present in up to 30% of older pts undergoing
surgery
Cardiac dysrhythmias[VF] are the major cause of
sudden death.

Risk Factors for Development of
Ischemic Heart Disease
 Male gender
 Increasing age
 Hypercholesterolemia
 Hypertension
 Cigarette smoking
 Diabetes mellitus
 Obesity
 Sedentary lifestyle
 Genetic factors
 Family history of premature
ischemic heart disease (male
<55 yrs of age, female <65 yrs)

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 Patients with ischemic
heart disease can present
with chronic stable angina
or with acute coronary
syndrome.
 The latter includes ST
elevation myocardial
infarction (STEMI) on
presentation and unstable
angina/non–ST elevation
myocardial infarction
(UA/NSTEMI)

Screening & Evaluation
 History:
 Symptoms such as angina and dyspnoea may be
absent at rest
 Emphasizing the importance of evaluating the
patient's response to various physical activities such
as walking or climbing stairs
 Limited exercise tolerance in the absence of
significant lung disease is very good evidence of
decreased cardiac reserve.
 If a patient can climb two to three flights of stairs
without symptoms, it is likely that cardiac reserve is
adequate.
 Silent Myocardial Ischemia
 Previous Myocardial Infarction
 Co-Existing Noncardiac Diseases
 Current Medications

Physical examination
 Signs of right and left ventricular
dysfunction must be sought.
 A carotid bruit may indicate
cerebrovascular disease.
 Orthostatic hypotension may
reflect attenuated autonomic nervous
system activity due to treatment with
antihypertensive drugs.
 Jugular venous distention and
peripheral edema are signs of right
ventricular failure.
 Auscultation of the chest may reveal
evidence of left ventricular
dysfunction such as an S3 gallop or
rales.

 Family history ➣

Clinical Predictors of Increased
Perioperative Cardiovascular Risk

An algorithm for preoperative assessment
of patients with ischemic heart disease

Special cardiac Investigation
12-lead ECG:
➣ May not show any abnormalities at rest or
w/ no symptoms, or may show evidence of
old MI (Q waves in 2 or more leads & >1/3 of
the QRS complex length)
➣ May reveal ST segment depression >1 mm
from baseline w/ angina pectoris or ST-
segment elevation w/ AMI or variant angina
➣ Other changes with symptoms of angina
pectoris: reversible T-wave inversion
➣ Other findings with AMI: increased T-wave
amplitude, followed by ST elevation,
followed by Q-wave development &
resolution of ST elevation

Echocardiography
 Can be used to assess
global cardiac function.
 It can also be used to assess
regional wall motion
abnormalities & detect the
presence of previous
myocardial injury.
 LV function assessment is a
major determinant of long-
term prognosis.
 It is also used to diagnose
LV thrombus in case of
apical & anterior wall MI

Exercise electrocardiography
 It is less accurate than
imaging studies to
establish diagnosis of IHD
but can give an idea about
LV function & prognosis.
 It may not be feasible in
patients with severe PVD,
limited exercise tolerance,
paced rhythm, abnormal
ST segment or aortic
stenosis.

Stress echocardiography
 This is used with pharmacologic induction of cardiac
stress (dobutamine) or exercise to look at LV
segmental wall function at rest & with stress.
 This can be also used to differentiate between viable
(hibernating, stunned) & nonviable (infarcted)
myocardial segments.
 Echocardiography at rest can be used to assess LV
function, which is an important prognostic variable.

.
Nuclear stress imaging:
 is used to assess coronary perfusion at rest & after
stress.
 Nuclear tracers (technetium, thallium) are used to
measure coronary blood flow.
 Positron emission tomography:
 May be used to demonstrate regional myocardial
blood flow & metabolism, & hence viability.

Coronary angiogram
Coronary angiography :
 Provides information about the
coronary anatomy & the extent &
location of the lesions.
 It is indicated in pts w/ unstable
angina despite maximal therapy.
 It can provide a road map to
coronary revascularization & the
feasibility of percutaneous
angioplasty or surgical treatment
depending on the characteristics &
location of the lesions.
 Cardiac enzyme elevation:
 Troponin is more specific than CK-MB
; increases within 4 hours after AMI &
remains elevated up to 1 wk.

Preoperative preparation
 AHA Guideline Update
on Perioperative
Cardiovascular
Evaluation for
Noncardiac Surgery
can be used for risk
stratification of
patients with IHD

Risk stratification
➣ Variables related to 4 major categories:
 Nature of surgery (high, moderate or low risk),
 Presence of IHD,
 Presence of CHF
 Presence of cerebrovascular disease
➣ Presence of comorbid conditions(diabetes mellitus,
aortic stenosis, PVD)
➣ Exercise tolerance
➣ Studies may be ordered if disease severity has not
been assessed previously.

Goldman's index of cardiac risk
in noncardiac procedures

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 History & physical exam to assess extent of disease,
exercise tolerance & symptom pattern, in addition to
history of comorbid diseases.
 Elective surgery in pts with a history of AMI should be
delayed up to 6months after the episode of AMI if
possible.
 Intraoperative tachycardia can increase the risk of
intraoperative ischemia & perioperative MI.
 Silent myocardial ischemia may be seen as only ECG
changes with no history of symptoms.
 Almost 70–75% of ischemic episodes in IHD pts are silent,
as well as 10–15% of AMIs.

.
■ Continue beta blockers; they were found to increase
long-term survival in patients with IHD.
■ Calcium channel blockers do not increase the negative
inotropic & vasodilatory effects of inhalational agents
but may potentiate the effects of depolarizing &
nondepolarizing muscle relaxants.
■ Stop ACE inhibitors the night before surgery to avoid
severe hypotension intraoperatively.
■ Stop aspirin 1 wk before surgery if possible;
anticoagulation must be held to decrease risk of
bleeding.

.
■ Patients with coronary stents should have their surgery
delayed at least 4 wks after stenting when possible.
■ Lifestyle modification may affect exercise tolerance
(smoking cessation, diet).
■ Cholesterol & triglyceride levels should be kept within
acceptable range.
■ Preop studies (ECG, chest x-ray, echocardiogram, etc.)
may be indicated depending on risk stratification, IHD
severity & disease progression

Preoperative Medication
Goal-Minimizing the sympathetic system effects on the
myocardium helps decrease the possibility of ischemic
events perioperatively. This can be achieved by:
➣ Anxiolysis with sedatives/narcotics
(benzodiazepines, opioids, scopolamine 0.4–0.6 mg
IM or 0.2–0.4 mg IV)
➣ Continuation or administration of beta blockers
 Administration of nitroglycerine
 Maintain heart rate & blood pressure within 20% of
normal values.

Preoxygenation
Aim –Replacement of air in Holding anaesthesia mask on
FRC[20-30ml/kg] with the face
enriched O2

O2 -15 L/min for 3 min

Anesthesia
■ Induction :
➣ The main goal during
induction is to avoid
hypertension &
tachycardia, thereby
decreasing drastic
cardiac events.
➣ Minimize extreme
variation in heart rate &
blood pressure.

.
 Control cardiovascular
response to tracheal
intubation by keeping low
duration of
laryngoscopy(<15sec) or by
pharmacologic means.
 Pharmacologic interventions
include lidocaine IV 1.5 to 2
min before intubation (1.5–2
mg/kg), intratracheal
lidocaine (2 mg/kg) at the
time of laryngoscopy, IV
fentanyl 13 micrograms/kg, IV
esmolol or IV nitroprusside

Nitroglycerin
➣ Continuous nitroglycerine
infusion was not found to
decrease the incidence of
intraoperative myocardial
ischemia.
➣ Avoid induction agents
capable of stimulating
sympathetic nervous system
(ketamine, pancuronium)

Regional Anesthesia
 Regional anesthesia may be preferred to general
anesthesia if possible, as it tends to better block
the stress response to surgery.
 Hypotension associated with some regional
techniques should be corrected by fluids &
sympathomimetic agents
 Potential benefits of a regional anesthetic
include excellent pain control, a decreased
incidence of deep vein thrombosis in some
patients, and the opportunity to continue the
block into the postoperative period.
 However, the incidence of postoperative cardiac
morbidity and mortality does not appear to be
significantly different between general and
regional anesthesia.

Maintenance of Anaesthesia
➣ Volatile anesthetics
(isoflurane, desflurane &
sevoflurane) are safe to
use with IHD, provided
severe CHF is not
present.
➣ Alternative technique
may be high-dose
narcotic agent with
oxygen & nitrous oxide.

 Vecuronium, rocuronium, cisatracurium
are attractive choices for patients with
ischemic heart disease
 Avoid pancuronium to reduce
sympathomimetic activity.
 Increased sensitivity to muscle relaxants
may be seen in pts on calcium channel
blockers.
 Keep BP & heart rate within 20% of awake
values.
 Intraoperative ischemia may be treated
with beta blockers (esmolol) in case of
tachycardia, IV nitrates in the case of
hypertension, or IV sympathomimetics
& fluids with hypotension.
 Maintain intraoperative heart rate at less
than 80 bpm.

➣ Minimizing body heat loss is vital
. Body warming blanket
to avoid postop shivering &
precipitation of ischemic
myocardial events. This can be
achieved with warm IV fluids, warm
operating room atmosphere, forced
warm air covers & irrigation of the
surgical site with warm fluids.
➣ To maintain adequate myocardial
oxygen delivery, do not allow
hemoglobin to drop below 10
g/dL

Monitoring
 An important goal when
selecting monitors for
patients with ischemic heart
disease is to select those that
allow early detection of
myocardial ischemia
 Most myocardial ischemia
occurs in the absence of
hemodynamic alterations
 So one should be cautious
when endorsing routine use
of expensive or complex
monitors to detect
myocardial ischemia.

Monitors used depend on disease severity & operative
procedure complexity
➣ ECG: simplest & most commonly used. ST-segment
changes are principally used to diagnose myocardial
ischaemia.
➣ Pulmonary artery catheter: ischemia manifests as a
sudden increase in PCWP, in addition to new V waves in
case of new onset of ischemic mitral valve regurgitation.
➣ Central venous pressure may correlate with PCWP if EF
= 0.5 & there is no evidence of LV dysfunction.
➣ Transesophageal echocardiography: most sensitive to
detect intraoperative myocardial ischemia by detecting
new onset of regional wall motion abnormality

Wake up and Emergence
■ Proper pain control is key to avoid
myocardial ischemic events.
■ Muscle relaxants can be reversed with
neostigmine in combination with
glycopyrrolate, as the latter produces
less tachycardia. Nevertheless, atropine
can be used with no adverse effects as
long as the pt is adequately beta
blocked.
■ Continuous ECG monitoring w/ ST-
segment analysis is important to detect
any myocardial ischemic events.
■ Supplemental oxygen to maintain
adequate oxygen saturation is
important.
■ Adequate heart rate & BP control as
intraoperatively
■ Treat tachycardia or hemodynamic
instability.
■ Avoid & treat shivering.

Wake up and Emergence
 Early extubation is possible and
desirable in many patients as
long as they fulfill the criteria for
extubation.
 However, patients with ischemic
heart disease can become
ischemic during emergence
from anesthesia and/or weaning
with an increased heart rate and
blood pressure.
 These hemodynamic alterations
must be managed diligently.
Pharmacologic therapy with a β-
blocker or combined α- and β-
blockers such as labetalol can be
very helpful.

Intraoperative Events That Influence the Balance Between
Myocardial Oxygen Delivery and Requirements

Decreased Oxygen Delivery

 Decreased coronary blood flow
 Tachycardia
 Diastolic hypotension
 Hypocapnia (coronary artery [Pulse oxymeter]
vasoconstriction) Increased Oxygen Requirements
 Coronary artery spasm  Sympathetic nervous
 Decreased oxygen content system stimulation
 Anemia  Tachycardia
 Arterial hypoxemia  Hypertension
 Shift of the oxyhaemoglobin  Increased myocardial
dissociation curve to the left contractility
 Increased afterload
 Increased preload

PERIOPERATIVE MYOCARDIAL
INFARCTION
 500,000 to 900,000 perioperative MIs occur annually worldwide.
 The incidence of perioperative cardiac injury is a cumulative result of
preoperative medical condition, the specific surgical procedure,
expertise of the surgeon, the diagnostic criteria used to define MI, and
the overall medical care at a particular institution.
 The risk of perioperative death due to cardiac causes is less than 1% for
patients who do not have ischemic heart disease as evidenced by a
history of angina pectoris, electrocardiographic signs of MI, or
angiographically documented coronary artery disease.
 The incidence of perioperative MI in patients who undergo elective
high-risk vascular surgery is between 5% and 15%.
 The risk is even higher for emergency surgery.
 Patients who undergo urgent hip surgery have an incidence of
perioperative MI of 5% to 7%, whereas less than 3% of patients who
undergo elective total knee or hip arthroplasty have a perioperative MI.

Predictors of postoperative
myocardial ischaemia
Left ventricular hypertrophy
History of hypertension
Diabetes mellitus
Known ischaemic heart disease
Use of digoxin

Factors that can contribute to
perioperative myocardial infarction

Diagnosis of Perioperative
Myocardial Infarction
 The diagnosis of acute MI traditionally requires the
presence of at least two of the following three elements:
 (1) ischemic chest pain
 (2) evolutionary changes on the ECG
 (3) increase and decrease in cardiac biomarker levels.
 In the perioperative period, ischemic episodes are often
silent, that is, not associated with chest pain.
 Many postoperative ECGs are nondiagnostic.
 Nonspecific ECG changes, new-onset dysrhythmias, and
noncardiac-related hemodynamic instability can further
obscure the clinical picture of acute coronary syndrome in
the perioperative period

PACU or ICU
The goals of
postoperative
management are
prevent ischemia,
monitor for
myocardial injury, and
treat myocardial
ischemia/infarction

Contd
■ Supplemental oxygen is crucial.
■ Pain control to avoid excessive sympathetic
nervous system stimulation
■ Maintain adequate beta blockade.
■ 12-lead ECG as a baseline
■ Prevention of shivering & maintenance of
normothermia is crucial to avoid oxygen
desaturation & sympathetic nervous system
activation.
■ Maintaining adequate oxygenation & tight
pain control for 48 to 72 hr postop is very
important, since this is the period when the
likelihood of developing AMI is highest.

Contd
 It is of interest that
postoperative myocardial
reinfarction often occurs
48-72 hours postoperatively,
a period that could
correspond to
discontinuation of
supplemental oxygen and
less aggressive treatment of
pain
 Reasonable control of
blood glucose: keep blood
glucose levels 100–180
mg/dL

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Anaesthesia and ihd

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