Anaesthetic Considerations in Cardiac Patients

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Indian Journal of Anaesthesia, August 2007

Anaesthetic Considerations in Cardiac Patients Undergoing Non

Cardiac SurgeryTej K. Kaul1, Geeta Tayal2

Key words Peri-operative anaesthesia care, Cardiac diseases, Non cardiac surgery

1. Professor & Head, 2. Assistant Professor Deptt. of Anaesthesiology and Resuscitation, Dayanand Medical College & Hospital, Ludhiana.

Correspondence to: Geeta Tayal 1841, Street No. 6, Maharaj Nagar,Ludhiana. 141001. Email: [email protected]

Introduction

Administering anaesthesia to patients with preexist-

ing cardiac disease is an interesting challenge. Most com-

mon cause of peri-operative morbidity and mortality in

cardiac patients is ischaemic heart disease(IHD). IHD

is number one cause of morbidity and mortality all over

the world

1

. Among the estimated 25 million patients in theUnited States who undergo surgery each year, approxi-

mately 7 million are considered to be at high risk of IHD.

Indian figures are not available.Goldman et al reported

that 500,000 to 900,000 MIs occur annually worldwide

with subsequent mortality of 10-25%.Care of these pa-

tients require identification of risk factors, pre-operative

evaluation & optimization, medicaltherapy, monitoring and

the choice of appropriate anaesthetic technique and drugs.

Risk factors Influencing peri-operative cardiac

morbidityare:

i.Recent myocardial infarction ii.Congestive cardiac fail-ure iii.Peripheral vascular disease iv.Angina pectoris

v.Diabetes mellitus vi.Hypertension vii. Hypercholester-

olemia viii. Dysrrhythmias ix. Age x. Renal dysfunction

xi.Obesity xii.Life style and smoking

Risk stratification

In 1977, Goldman andcolleagues proposed the land-

mark Cardiac Risk Index2. Although not validated pro-

spectively, this index was used extensively for preopera-

tive cardiac risk assessment for the next two decades.

Subsequently, other cardiac risk indices were proposedand adopted. In 1996, a 12-member task force of the

American College of Cardiology and theAmerican Heart

Association (ACC/AHA) published guidelines regarding

the perioperative cardiovascular evaluation of patients

undergoing noncardiac surgery3. In March 2002, these

guidelines were updated based on new data. The overrid-

ing theme remains that “preoperativeintervention is rarely

necessary, simply to lower the risk of surgery, unless such

Indian Journal of Anaesthesia 2007; 51 (4) : 280-286

intervention is indicated irrespective of the perioperative

context”. No test should be performed unless it is likely

to influence patient treatment.

Evaluation

Patients having any sort of cardiac ailment need to

be evaluated properly preoperatively6.

History

History elicits the severity, progression and func-

tional limitation introduced by cardiac disease. History

should include:-.

1. Exercise tolerance :- It depicts the cardiac reserve.It

can be Excellent -history of participation in sports like

swimming, football, tennis, basket-ball, skating etc.

Adequate-patient able to climb stairs, run a short dis-

tance. Poor- able to do leisure activities only e.g.s low

ballroom dancing or canwalk aroundin thehouse only.

2. Angina pectoris:-It is the symptomatic manifestation

of myocardial ischaemia characterized by typical

substernal pain which is evoked by physical exertion

and relieved by rest or sublingual nitroglycerine.

3. Myocardial infarction:- The incidence of myocardial

infarction during the peri-operative period is related

to time period since the previous myocardial infarc-

tion. According to Tarhan et al – incidence of peri-

operative re-infarction is 37% if the time elapsed is

less than 3 months,16% when time elapsed is 4-6

months and 5% when time elapsed is more than 6

months. This is the basis for recommendation to wait

for 6 months after MI for elective major surgery.

4. Co-existing noncardiac diseases

i. Peripheral vascular disease ii. Cerebro vascular

disease iii. Chronic obstructive pulmonary disease in

patients with history of cigarette smoking iv. Renal

dysfunction may be associated with chronic hyper-

tension v. Diabetes- May be the cause of silent MI



281

vi. Anaemia, polycythemia, thrombocytosis when

present will need careful management.

5. Current medications-Awareness about the medica-tions that patient is taking is important during anaes-

thesia. All cardiac medications like beta blockers,

calcium channel blockers, nitrates should be contin-

ued until the morning of surgery.Patient may be on

oral anticoagulants or aspirin which should be stopped

5-7 days prior to surgery.

6. Con ge stive c ar dia c f a ilu re :- Th e s tr es s o f

anaesthesia,surgery and fluid replacement may re-

sult in overt failure in patients bordering on conges-

tive heart failure.

7. Dysrrhythmias.

Examination

A careful general physical examination should be

done. It should include assessment of vital signs like blood

pr es su re , pu ls e ra te an d rh yt hm, jug ul ar ve no us

pulse,oedema, pallor, cyanosis, clubbing , jaundice, lym-

phadenopathy. In systemic examination, cardiovascular

system should be examined for heart sounds & any mur-

mur. Further evaluation is needed as per the findings.

Respiratory system also needs to be assessed in details.

Laboratory investigations

Cardiac specific tests likeECG, echocardiography

to know ejection fraction, any valvular lesion , wall mo-

tion abnormalities, LV function and pressure gradients,

Holter monitoring, Treadmill test, thallium scintig-

raphy to detect myocardium at risk, radionuclide ven-

triculography, dobutamine stress test(DST) for evalu-

ating inducible ischemia in patients who have poor func-

tional capacity, coronary angiography in patients where

DST is positive should be done.

Anaesthetic managementAnaesthesia goals remain

i. Stable haemodynamics ii. Prevent MI by optimiz-

ing myocardial oxygen supply and reducing oxygen de-

mand iii. Monitor for ischaemia iv. Treat ischemia or inf-

arction if it develops v. Normothermia vi. Avoidance of

significant anaemia

Management depends upon the type of surgery

whether emergency or elective. For emergency surgery

proceed for the surgery with medical management of

cardiac ailment. For elective surgery perioperative man-

Cardiac risk indices

S .N o. Car di ac r is k va ri abl es P oi nt s C o mm e nt s

Goldman cardiac risk index 2

1 . Third heart sound or jugular 1 1

venous distension

2 . R ec ent myo ca rd ia l i nfarct ion 1 0 C ardi ac c omp li ca -

tion rate:

3 . N ons in us rh yth m or prema tur e 7 0-5 points = 1%

atrial contraction on ECG

4. More than 5 premature 7

ventricular contractions

5. Age more than 70 years 5 6-12 points = 7%

6. Emergency operations 4

7 . P oo r ge neral me di ca l c on di ti on 3 1 3-2 5 p oi nt s=1 4%

8 . In tr at hor ac ic , i nt ra per it on ea l 3 >26 points =78%

or aortic operation

9. Aortic stenosis 3

Detsky modified multifactorial index 4

1. Class 4 angina 2 0

2. Suspected critical aortic stenosis 20

3 . Myoc ard ia l i nfa rct ion wi thi n 1 0

6 months

4 . Alveolar pulmonary edema 1 0

within 1 week

5. Unstable angina within 3 months 10

6. Class 3 angina 1 0

7. Emergency operation 1 0

8 . Myoc ardial infarction more 5

than 6 months ago

9 . Alveolar pulmonary edema 5 Cardiac complica-

resolved more than 1 week ago t io n r at e:

1 0. Rhythm other than sinus or 5

PACs on EKG

11. More than 5 premature 5 > 15: high risk

ventricular contractions (PVC)

any time before surgery

1 2. Poor general medical status 5

13. Age more than 70 years 5

Eagle criteria for cardiac risk assessment 5

1. Age more than 70 years 1

2. Diabetes 1 <1: no testing

3. Angina 1 1-2 : send for

non-invasive test

4. Q waves on ECG 1

5. Ventricular arrhythmias 1 >3: send for

angiography

Tej K. Kaul et al. Non cardiac surgery in cardiac patients



282


agement depends upon various clinical risk factors and

surgery specific risk factors3.

Clinical risk factorsObtainedby history, physicalexamination & review of

ECG, theclinical risk factors are grouped into 3 categories-

1. Major clinical predictors are unstable coronary syn-

drome, decompensated heart failure, significant

dysrrhythmia and severe valvular disease. They man-

date intensive management even if that leads to de-

lay or cancellation except emergency surgery.

2. Intermediate clinical predictors aremild angina pecto-

ris, previous MI by history or pathological Q waves,

compensated or prior heart failure, insulin dependentdiabetes mellitus,and renal insufficiency. These are

markers of enhanced risk of peri-operative cardiac

complications. It appears reasonable to wait for 4-6

weeks after MI for elective surgery.

3. Minor clinical predictors are hypertension, LBBB,

nonspecific ST-T wave changes and history of stroke.

They have not proved to increase risk independently.

Surgery specific risk factors

1. High risk surgeries- (emergent major operations

particularly in the elderly, aortic and other major vas-cular surgery, anticipated prolonged surgical proce-

dures associated with large fluid shifts or anticipated

blood loss) are often reported to have a cardiac risk

of greater than 5%.

2. Intermediate risk surgeries- (carotid endarter-

ectomy, head and neck surgery, intraperitoneal and

intrathoracic surgery, prostate surgery) are reported

generally to have cardiac risk of less than 5%.

3. Low risk procedures:- (endoscopic procedures, su-

perficial procedures, cataract surgeries, breastsurgery)are reported to haveless than 1%risk of cardiacevents.

Preoperative management

At risk patients need to be managed with pharmaco-

logic and other perioperative interventions that can ame-

liorate perioperative cardiac events . Three therapeutic

options are available before elective noncardiac surgery.-

1. Optimisation of medical management

2. Revascularization by PCI, revascularization by sur-

gery ( CABG)

However it may not be necessary to intervene pre-

operatively (except for beta blocker therapy or 2

ago-

nists) to improve perioperative outcome. Beta blockers

have been shown to be useful in reducing perioperative

morbidity and mortality in high risk cardiac patients and

preferably titrated to a heart rate of 50 to 60 bpm7. 2

agonists by virtue of their sympatholytic effects can be

useful in patients where beta blockers are contraindicated.

Nitroglycerine lowers LVEDP by reducing preload . It

improves collateral coronary flow and reduce systemic

B.P. Other agents like calcium channel blockers , ACE

inhibitors, aspirin, insulin, statins prove to be beneficial

perioperatively.

Coronary intervention should be guided by patient’scardiac condition( unstable angina, left main or equivalent

CAD, three vessel disease,decreased LV function) and

by the potential consequences of delaying the noncardiac

surgery for recovery after coronary revascularization3

.Patients who underwent PCI had better outcome after

noncardiac surgery. However the need for dual anti-plate-

let therapy for several months to one year can signifi-

cantly impact the perioperative course. Acute postopera-

tive stent thrombosis has been reported when anti-plate-

let agents were temporarily held preoperatively to reduce

chance of bleeding. Continuing the therapy can lead tosignificant postoperative bleeding. Discontinuing or modi-

fyinganti-platelet therapyshould involve a multidisciplinary

team of cardiologist, surgeon, anaesthesiologist 8 .

Preanaesthetic considerations

Preoperative visit to the patient is very important.A

good rapport should be made with the patient and written

consent obtained. Patient should be explained about the

risk of surgery and anaesthesia.It is important to continue

the medications till the day of surgery like beta

blockers,calciumchannelblocker ,digitalis.Potassium level

should be normal as hypokalemia can cause digitalis tox-

icity. Anticoagulants should be stopped.

Premedication

Significance of premedication in allaying anxiety in

cardiac patients is of paramount importance. This is to

prevent increase in B.P. and HR which can disturb the

myocardial oxygen supply and demand and can induce

ischaemia. Any combination of benzodiazepine like

lorazepam and opioid like morphine should be given one

hour prior to arrival in operation theatre.



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The following algorithm helps in easy reference for planning perioperative management of cardiac patients

undergoing noncardiac surgery.



284


Intraoperative management

Monitoring

Incidence of ischaemia in the intraoperative periodis low( as compared with pre and postoperative period)

i. ECG is the most commonly used monitoring tool .

If ECG is to be used effectively as an ischaemic monitor,

the monitor should be set on diagnostic mode. Monitoring

three ECG leads ( II,V4,V5 or V3,V4,V5 ) improves rec-

ognition of ischaemia. The ST segment trending system

also helps in the detection of ischaemia ii. Blood pressure

iii. Pulse oximetry iv. Capnography v. Temperature moni-

toringvi.Urine outputmonitoring vii. Central venous pres-

sure viii. Pulmonary artery pressure and cardiac output–

can be measured with pulmonary artery catheter as re-

quired. In a haemodynamically unstable patient, the re-

quirement of volume or inotropes can be judiciously cal-

culated and response monitored closely ix. TEE

(transesophageal echocardiography) is a sensitive moni-

tor for ischaemia. However TEE is not advocated for

routine use 9.

Choice of anaesthetics

The anaesthesiologist should select the drugs with

theobjective of minimizing demandandoptimum supplyof

oxygen. Along with the anaesthetic agent some cardiac

drugs should be readily available to maintain

haemodynamics, to prevent & treat ischaemia, if it occurs.

General anaesthesia

1. Intravenous anaesthetics

Thiopentone— It reduces myocardial contractil-

ity, preload and blood pressure and there is slight in-

crease in heart rate. It should be administered slowly

and with caution.

Propofol- —It reduces arterial blood pressure andheart rate significantly. There is dose dependent reduc-

tion in myocardial contractility.It can be used in with good

ventricular function but is not good induction agent for

patients with CAD.

Ketamine- —It is not goodin IHD and valvularheart

disease patients.It is however a useful agent in situations

like cardiac tamponade and cyanotic heart disease.

Midazolam— It produces decrease in mean arte-

rial pressure and increase in heart rate. It provides excel-

lent amnesia and is widely used for patient with CAD

Etomidate— It causes minimum haemodynamic

changes. It is excellent for induction in patients with poor

cardiac reserve.2. Narcotics —Morphine is the preferred drug for

its relative cardiac stability and very good analgesic

effect.It produces arterial and venous dilatation ,resulting

in reduction of afterload and preload.Newer narcotic an-

algesic agents like fentanyl, alfentanyl and sufentanil also

provide adequate cardiac stability and pain relief.

3. Inhalational agents- Isoflurane is recommended

in patients with good myocardial contractility. Halothane

has the disadvantage of myocardial depression and po-

tential of dysrrhythmias.4. Nitrous oxide —It provides stablehaemodynamics

in cardiac patients.

5. Muscle relaxants-Vecuronium produces mini-

mum haemodynamic alterations and is short acting , there-

fore suitable for use in cardiac patients. Pipecuronium,

mivacurium, doxacurium are newer non depolarizing

muscle relaxants without any significant cardiovascular

side effects.

6. Glycopyrrolate —It is preferred over atropine

since it produces less tachycardia & should be used onlyif specifically required.

Regional anaesthesia

The potential and well known advantage of regional

anaesthesia over G.A should be an asset in cardiac pa-

tients if the surgery can be performed under regional block.

Patient should be nicely premedicated without any appre-

hension. Disadvantages of regional anaesthesia include

hypotension fromuncontrolled sympathetic blockade and

need for volume loading can result in ischemia. Care

should be taken while giving local anaesthetic becauselarger doses can cause myocardial toxicity and myocar-

dial depression. Use of epinephrine with local anaesthetic

is not recommended10.

Managing intraoperative complications

1) Intraoperative ischaemia

1 If patient is haemodynamically stable—

1- Beta blockers ( I/V metoprolol upto 15mg)

I/V Nitroglycerine

Heparin after consultation with surgeon



285


2 If patient is haemodynamically unstable-

Support with inotropes

Use of intraoperative ballon pump may be nec-essary

Urgent consultation with cardiologist to plan for

earliest possible cardiac catheterization

2) Other complications like dysrrhythmias, pacemaker

dysfunction should be managed accordingly

Post operative management

Goals are same as intraoperative

i. Prevent ischaemia ii. Monitor for MI iii. Treat-

ment for MI

Although most cardiac events occur within first 48

hours, delayed cardiac events (within first 30 days ) still

happen and could be the result of secondary stress. Post

operative stress of extubation, pain, sepsis, haemorrhage,

anaemia, respiratory problems can increase the demand

on the heart and should be minimized and treated.

Valvular heart diseases

Patients with valvular heart diseases coming for

surgery present many challenges to the anaesthesiologist.

Now it is no longer necessary or even advisable to delay

surgery until advanced symptoms are present. Valvular

surgery is advised in such patients before elective non-

cardiac surgery. The perioperative physician has to be

aware of the varying effects of haemodynamic variables

on this sub population of patients. The five variables in

dealing with the valvular heart diseases are important.

They are:- i. Preload ii.Afterload iii. Myocardial contrac-

tility iv. Heart rate v. Rhythm.

Keeping in mind these variables , the anaesthetic

technique can be chosen with a view to maintain optimal

cardiac performance. In general ,the goal in stenotic le-

sions is to enhance forward flow , where as in regurgitant

lesions is to decrease regurgitant flow . All the patients

with valvular heart disease undergoing non-cardiac sur-

gery should get antibiotic prophylaxis to prevent infective

endocarditis. AHArecommends ampicillin, 2 g I.M or I.V

plus gentamicin 1.5 mg.kg-1 I.M or I.V 30 min. before

procedure and 6 hrs later ampicillin 1 gm I.M or I.V. For

patients allergic to penicillin, vancomycin 1 gm I.V is rec-

ommended. For dental and endoscopic procedures, oral

amoxicillin 2gm or cephalexin 2 gm or azithromycin 500

mg ,1 hr. before the procedure is given. Use of oral anti-

coagulants in patients with mitral stenosis who have atrial

fibrillation should be kept in mind. Tachycardia is detri-

mental in both aortic and mitral stenosis. In MR and AR ,

it is advisable to maintain normal to high heart rate and

mild vasodilatation to decrease the amount of regurgitant

flow. InAS consideration should be given to the possibil-

ity of CAD 11

Hypertension

Hypertension is the commonest cardiac disease all

over the world. These patients are documented to have

associated CAD, left ventricular dysfunction, renal failure

which increase the perioperative risk. Hence it is advisable

to control BP preoperatively. But this does not need sur-

gery to be deferred for weeks, to achieve ideal blood pres-sure control, in patients with mild to moderate hyperten-

sion. It is also important to evaluate for target organ dam-

age. It is advisable to continueantihypertensives till theday

of surgery. For patients with marked elevations of BPintra

or post operatively should be managed by either nitroglyc-

erine or sodiumnitroprusside by I.V. infusion. Intraarterial

B.P. monitoring is recommended for such patients. Any

factors of sympathetic stimulus should be avoided.

Dysrrhythmias

Dysrrhythmias may be a marker of severity of un-derlyingCAD or left ventricular dysfunction.Asymptom-

atic ventricular ectopics with stable haemodynamic pa-

rameters do not need any treatment preoperatively. Simi-

larly prophylactic treatment is not required in supraven-

tricular tachycardia . In atrial fibrillation rate needs to becontrolled . Perioperatively if they occur can be treated

by calcium channel blockers ,beta blockers,adenosine.

Patients with conduction delay ,LBBB do not re-quire pacing unless there is history of syncope.But in com-

plete heart block, patients need to be paced.In patients on

permanent pace makers ,electro cautery should be used

with caution and for minimum period of time.The cau-

tery plate should be as far as possible from the heart .Useof bipolar cautery decreases the risk of pacemaker dys-

function. Use of magnet will turn pace maker into asyn-

chronous mode , preventing unwanted inhibition.

The material submitted remains only an overview

of the guidelines, which will continue changing from time

to time, depending upon the evidence procured over a

period of time. Also the techniques need to be tailored

varying from patient to patient, surgical needs and the

facilities available.



286


References

1. Hall MJ, Owings MF. 2000 National Hospital Discharge Sur-

vey. Hyattsville, MD: Department of Health and Human Ser-vices; 2002. Advance Data From Vital and Health Statistics,

No. 329.

2. Goldman L,Caldera D,Nussbaum S, et al. Multifactorial index of

cardiac risk in noncardiac surgical procedures. N Engl J Med

1977;297:845.

3. Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guideline

update for perioperative cardiovascular evaluation for noncar-

diac surgery-executive summary. A report of the American Col-

lege of Cardiology / American Heart Association Task Force on

Practice Guidelines (Committee to update the 1996 guidelines

on Perioperative CardiovascularEvaluation for NoncardiacSur-

gery).Anesth Analg 2002; 94:1052.

4. Detsky AS, Abrams HB, Forbath N , et al. Cardiac assessment

for patients undergoing noncardiac surgery. Amultifactorial clini-

cal risk index. Arch Intern Med 1986; 146:2131.

5. Eagle K, Brundage B, Chaitman B, et al. Guidelines for

perioperative cardiovascular evaluation for non-cardiac surgery.

AHA/ACC task force report. J Am Coll Cardiol 1996; 27:910.

6. Stoelting RK, Dierdorf S. Ischemic heart disease. In:Stoelting

RK, Dierdorf S, editors. Anesthesia and co-existing disease. 4th

edition. Philadelphia. Churchill Livingstone 2002. p.2-8.

7. London MJ, Zaugg M, Schaub MC, et al. Perioperative beta-

adrenergic receptor blockade: physiologic foundations and clini-

cal controversies. Anesthesiology 2004; 100:170.

8. Dupuis JY, Labinaz M. Noncardiac surgery in patients with

coronary artery stent : what should the anaesthesiologist know

? Can J Anaesth 2005;52:356.

9. Barash PG.Sequential monitoring of myocardial ischemia in the

perioperative period.In: American Society ofAnaesthesiologists

R ev ie w L ec tu re s. At la nt a: A me ri ca n S oc ie ty o f

Anaesthesiology;2005.p.411.

10. Breen P, Park K W. General anesthesia versus regional anesthe-

sia. Int Anesthesiol Clin 2002; 40:61.

11. BonowRO, Carabello B, de LeonAC Jr, et al.Guidelines for the

management of patients with valvular heart disease: Executive

summary: a report of theAmerican College of Cardiology /Ameri-

can Heart Association Task Force on Practice Guidelines (com-

mittee on management of patients with valvular heart disease).

Circulation 1998;98:1949-84.

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