Transcript anaesthetic considerations in a patient with coronary artery disease

Dr. Pooja Murthy
University College of Medical
Sciences & GTB Hospital, Delhi
www.anaesthesia.co.in
email: [email protected]
WHY THIS TOPIC ?
 IHD
is present in 30% of patients undergoing
noncardiac surgeries.
 Increased
perioperative cardiovascular mortality and
 Increased
in total health care expenditure.
morbidity.
 Increased
chances of poor outcome in 1-2 yrs
following surgeries
MOST IMPORTANT – Perioperative MI
 Incidence
- <1% in patients who do not
have CAD
- 5 -15% in patients undergoing
high risk surgeries
 Most perioperative MI occur in the first 24
– 48 hrs of surgery.
 Most common is NSTEMI. ( preceded by
tachycardia and ST depression )
These generally follow peri op MI.
1) Cardiac dysrhythmias:
a. Ventricular fibrillation
b. Ventricular tachycardia
c. Atrial fibrillation
d. Bradydysrhythmias and heart block
2) Pericarditis
3) Mitral regurgitation
4) Ventricular septal rupture
5) Heart failure and cardiogenic shock
6) Myocardial rupture
7) CVA
IHD mainly occurs because of narrowing of
the lumen of coronary arteries due to :
1. Atherosclerosis (most common)
2. Emboli
3. Spasm
4. Aortitis
5. Cong. Abnormalities of coronary arteries
Coronary circulation normally supplies sufficient blood
flow to meet the O2 demands of the myocardium in
response to widely varying workloads.
myocardial O2 supply
(coronary blood flow
& O2 content)
myocardial O2 demand
IMBALANCE
IHD
Determinants of myocardial O2 demand are:
MAJOR DETERMINANTS
Myocardial contractility
Heart rate
Wall stress
MINOR DETERMINANTS
Muscle shortening
Activation
Determinants of myocardial Oxygen supply:
Coronary blood flow
Diastole
% increase in MVO2 above resting value
Determinants of myocardial oxygen supply/demand ratio
Muscle shortening
Activation
Basal metabolic requirement
% increase of each factor above resting value
Classification of CAD
CAD
Stable Angina
Acute Coronary
Syndromes
Unstable
NSTEMI
Angina
STEMI
ISCHEMIC TYPE OF CHEST PAIN
NEW ONSET / CHANGE FROM
Partial occlusion
/ chronic
narrowing of
COR.ARTERY
BASELINE
CSA
Tp/CKMB
- ve
NO ST
elevation
UA
Tp/CKMB
+ ve
NSTEMI
ACS
12 lead ECG
Complete
occlusion of
COR.ARTERY
ST elevation
Tp/CKMB
+ ve
Myocardial
Infarction
STEMI
 Pre
operative evaluation
 Intraoperative
 Post
management
operative management
Goals:
1) To know if the patient is on his/ her
optimal medical regimen
2) To know the severity of IHD
3) To know the ischemic threshold
4) Ventricular function
Drug Interactions during Anaesthesia
Nitrates
Beta blockers
Statins
Antiplatelets
ACE I or ARBs
CCBs
Digitalis
Diuretics
Venodilation - hypotension
Bradycardia with opioids
Liver dysfunction
Increased bleeding
Hypotension
AV block with ß blockers
Toxicity
Hypokalemia (dysrhythmias)
 All
cardiac medications (except ARBs) like
beta blockers, calcium channel blockers,
nitrates ,statins should be continued until the
morning of surgery.
 Antiplatelets:
aspirin or ADP antagonists
which should be stopped at various time
intervals (depending on the cardiac risk and
risk of surgery )
Unstable coronary syndromes
- unstable/severe angina( CCS class III & IV)
- recent MI( acute MI < 7 days,recent –7days to 1mth)
Decompensated heart failure
(NYHA class IV, new onset/worsening HF )
Significant arrhythmias
(High degree heart blocks, ventricular arrhythmias
symptomatic tachy and bradycardias )
Severe valvular disease
(severe AS or symptomatic MS)
Detected of clinical risk factors as given by
RCRI ( previously intermediate risk
factors ). These include :
 h/o IHD
 h/o compensated / prior HF
 h/o CVD
 Renal insufficiency
 Diabetes mellitus
II: ASSESSMENT OF FUNCTIONAL CAPACITY
1 MET Can you….
take care of yourself ?
Eat, dress, or use of toilet ?
4 METS
Can you….
Climb a flight of stairs walk up a hill ?
Walk on level ground at 4 mph
run a short distance ?
Walk indoors around the house ?
Walk a block or 2 on level
ground at 2 to 3 mph
Do light work around the house
like dusting or washing dishes ?
Do heavy work around the
house like scrubbing the floor or
lifting or moving heavy furniture ?
Participate in moderate recreational
activities like golf, bowling, dancing,
double tennis, baseball or football ?
4 METS
Participate in strenuous sports like
swimming, single tennis, football,
basketball or skiing ?
Greater than
10 METS
Surgical procedures :
- emergency surgery has 2- 5% higher
cardiovascular risk when compared to
elective surgeries.
Cardiac risk stratification ( combined incidence
of cardiac death and nonfatal MI )
Risk stratification
Procedures
High risk ( cardiac risk > 5% )
Aortic and major vascular surgery.
Peripheral vascular surgeries.
Intermediate risk ( 1- 5%)
Intraperitonial and intrathoracic
surgeries.
Surgeries : carotid endartectomy,
head and neck surgery
orthopedic surgery
prostate surgery
Low risk ( <1%)
Endoscopic procedures
Superficial procedures: cataract
surgeries, breast surgeries, ambulatory
surgery.
Preoperative Resting 12-Lead ECG
CLASS I
1. Preoperative resting 12-lead ECG is recommended
for patients with at least 1 clinical risk factor who are
undergoing vascular surgical procedures. (Level of
Evidence: B)
2. Preoperative resting 12-lead ECG is recommended
for patients with known CHD, peripheral arterial
disease, or cerebrovascular disease who are
undergoing intermediate-risk surgical procedures.
( Level of Evidence: C)
Class II:
Pre operative 12 lead ECG is reasonable in patients
with no clinical risk factors who are undergoing
vascular surgical procedures
Pre operative 12 lead ECG is reasonable in patients
with at least 1 clinical risk factor who are
undergoing intermediate risk surgeries
Presence of LV hypertrophy or ST segment
depression on 12 lead ECG predicts adverse
perioperative cardiac events.
Assessment of LV function :
( by ECHO, radionuclide angiography, contrast
ventriculography )
No class I recommendation.
It is reasonable( class II, C) in:
1. Pts with dyspnoea of unknown origin
2. Current or prior heart failure with worsening
heart failure or change in clinical status.
This includes:
1. Exercise stress testing –
exercise ECG testing.
2.
Pharmacological stress testing.
•
Nuclear myocardial perfusion
imaging
•
Dobutamine stress
echocardiography.
ambulatory pts. – exercise ECG testing
( except in pts with abdominal aortic
aneurysms)
 In
 In
pts with abnormal resting ECG ( LBBB, LV
hypertrophy with strain pattern, digitalis
effect) – nuclear myocardial perfusion
imaging.
pts who cannot exercise – non exercise
stress test.
 In
Goals :
1. Prevent ischemia
2. Monitor for myocardial injury
3. Treatment of ischemia / infarction
Premedication
- Benzodiazepines
- α2 agonists
Monitoring
Routine monitors:
1. ECG – lead II, V5 ( 2 lead )
- lead II, V4, V5 ( 3 lead )
- lead II, V3 ,V5 ( 3 lead )
2. Blood pressure
3. Pulse oximetry
4. Capnography
5. Temperature monitoring
Special monitors:
1. Pulmonary artery catheter
2. Trans esophageal ECHO
Indicated in pts with hemodynamic
instability..
GOAL:
 To maintain a balance between myocardial
oxygen demand and supply.
Strategies :
Optimize hemodynamics
Correct Anaemia
Maintain temperature (≥35 degree)
Maintain blood glucose ≤150 mg/dl (Class IIa)
Prevent pain
Decreased O2 delivery:
 Decreased coronary blood flow
 Tachycardia
 Diastolic hypotension
 Hypocapnia
 Coronary artery spasm
 Anemia
 Arterial hypoxemia
 Shift of O2 dissociation curve to left
Increased O2 requirement:
 Sympathetic stimulation
 Tachycardia
 Hypertension
 Increased myocardial contractility
 Increased afterload
 Increased preload
It is recommended to keep Heart rate and
Blood pressure within 20% of awake value
intraoperatively…
Anaesthesia technique:
General anaesthesia, regional anaesthesia,
monitored anaesthesia care – any
technique can be used but hemodynamic
stability must be ensured.
- Intravenous cannulation (pain free)
- Premedication – opioids ( morphine,
fentanyl ) , benzodiazepines
- Inducing agents :
Any intravenous inducing agents can be
used except ketamine.
Muscle relaxants:
NDMRs / Succinylcholine can be used.
NDMRs:
Vecuronium , rocuronium, cisatracurium
preferred – minimum/ no effect on HR and BP
Atracuium – less preferred because of histamine
release.
Pancuronium - increases HR and BP and
incidences of myocardial ischemia has been
reported.
Prevention of intubation response:
•
•
•
•
•
•
Short duration of laryngoscopy ( < 15sec)
Laryngotracheal lidocaine
I V Lidocaine 1.5 – 2mg/kg – 2 to 3 min
before intubation
I V Esmolol 0.5 – 1mg/kg – 90 sec before
intubation
I V Remifentanil (1.0 g/kg) 1 min,
Alfentanil (10–20 g/kg) 2–3 min, or Fentanyl
(0.5–1.0 g/kg) 4–5 min
Diltiazem, oral clonidine(0.2mg),
dexmeditomedine infusion (1µg/kg).
Volatile anaesthetic agents
( halothane less preferred because of
myocardial depression )
•
•
Maintenance of hemodynamic stability
•
Maintenance of euglycemia
•
Maintenance of normothermia
•
Adequate analgesia
Reversal of NMB :
Anticholinesterase/ anticholinergic drug can
safely be used
Prevent extubation response
Glycopyrrolate preferred over atropine.
Diagnosis :
ST segment elevation / depression of at
least 1mm on ECG
Steps in management :
Prompt and aggressive treatment of
changes in heart rate and blood pressure
is indicated
 Increase
in heart rate – beta blockers e.g.
esmolol
 Increase in BP – NTG
 Decrease in BP – fluid infusion +
sympathomimetic drugs
 Unstable
hemodynamic situation :
- Circulatory support
- Inotropes
- Intra aortic balloon pump counter pulsation
Plan early post op cardiac catheterization.
 Goal:
- Maintain myocardial perfusion
- Minimize haemodynamic stress
 Things
to be cautious about:
- Intra op hypothermia – predisposes to
post op shivering
- pain, hypoxia, hypercarbia, sepsis, blood
loss – increases myocardial O2 demand

Continue beta blockers and other
medications

Prevention of hypovolemia and hypotension

Correction of anemia

Continuous ECG monitoring to detect silent
ischemia
 ACC/
AHA 2007 Guidelines on
perioperative cardiovascular evaluation
and care for non cardiac surgeries.
 Kaplan’s textbook of cardiac anaesthesia –
5th edition
 Stoelting’s Anaesthesia
and Coexisting
disease – 5th edition
 Braunwald’s Heart Disease – 8th edition
 Miller’s Anaesthesia – 7th edition
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