Anaesthetic considerations in cardiac patients undergoing non

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Indian Journal of Anaesthesia, August 2007

Anaesthetic Considerations in Cardiac Patients Undergoing NonCardiac Surgery

Tej 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]

IntroductionAdministering anaesthesia to patients with preexist-

ing cardiac disease is an interesting challenge. Most com-mon cause of peri-operative morbidity and mortality incardiac patients is ischaemic heart disease(IHD). IHDis number one cause of morbidity and mortality all overthe world1.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 reportedthat 500,000 to 900,000 MIs occur annually worldwidewith subsequent mortality of 10-25%.Care of these pa-tients require identification of risk factors, pre-operativeevaluation & optimization, medical therapy, monitoring andthe choice of appropriate anaesthetic technique and drugs.

Risk factors Influencing peri-operative cardiacmorbidity are:

i.Recent myocardial infarction ii.Congestive cardiac fail-ure iii.Peripheral vascular disease iv.Angina pectorisv.Diabetes mellitus vi.Hypertension vii. Hypercholester-olemia viii. Dysrrhythmias ix. Age x. Renal dysfunctionxi.Obesity xii.Life style and smoking

Risk stratificationIn 1977, Goldman and colleagues 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 theAmerican College of Cardiology and the American HeartAssociation (ACC/AHA) published guidelines regardingthe perioperative cardiovascular evaluation of patientsundergoing noncardiac surgery3. In March 2002, theseguidelines were updated based on new data. The overrid-ing theme remains that “preoperative intervention is rarelynecessary, simply to lower the risk of surgery, unless such

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

intervention is indicated irrespective of the perioperativecontext”. No test should be performed unless it is likelyto influence patient treatment.

EvaluationPatients having any sort of cardiac ailment need to

be evaluated properly preoperatively6.

HistoryHistory elicits the severity, progression and func-

tional limitation introduced by cardiac disease. Historyshould include:-.

1. Exercise tolerance :- It depicts the cardiac reserve.Itcan be Excellent -history of participation in sports likeswimming, 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. slowballroomdancing or can walk around in the house only.

2. Angina pectoris:-It is the symptomatic manifestationof myocardial ischaemia characterized by typicalsubsternal pain which is evoked by physical exertionand relieved by rest or sublingual nitroglycerine.

3. Myocardial infarction:- The incidence of myocardialinfarction during the peri-operative period is relatedto 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 isless than 3 months,16% when time elapsed is 4-6months and 5% when time elapsed is more than 6months. This is the basis for recommendation to waitfor 6 months after MI for elective major surgery.

4. Co-existing noncardiac diseasesi. Peripheral vascular disease ii. Cerebro vasculardisease iii. Chronic obstructive pulmonary disease inpatients with history of cigarette smoking iv. Renaldysfunction may be associated with chronic hyper-tension v. Diabetes- May be the cause of silent MI

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vi. Anaemia, polycythemia, thrombocytosis whenpresent 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 onoral anticoagulants or aspirin which should be stopped5-7 days prior to surgery.

6. Congestive cardiac failure:-The stress ofanaesthesia,surgery and fluid replacement may re-sult in overt failure in patients bordering on conges-tive heart failure.

7. Dysrrhythmias.

ExaminationA careful general physical examination should be

done. It should include assessment of vital signs like bloodpressure, pulse rate and rhythm, jugular venouspulse,oedema, pallor, cyanosis, clubbing , jaundice, lym-phadenopathy. In systemic examination, cardiovascularsystem 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 investigationsCardiac specific tests like ECG, 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 whereDST 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 ofsignificant anaemia

Management depends upon the type of surgerywhether emergency or elective. For emergency surgeryproceed for the surgery with medical management ofcardiac ailment. For elective surgery perioperative man-

Cardiac risk indicesS.No. Cardiac risk variables Points Co mments

Goldman cardiac risk index 2

1. Third heart sound or jugular 11venous distension

2. Recent myocardial infarction 10 Cardiac complica-tion rate:

3. Nonsinus rhythm or premature 7 0-5 points = 1%atrial contraction on ECG

4. More than 5 premature 7ventricular contractions

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

6. Emergency operations 4

7. Poor general medical condition 3 13-25 points=14%

8. Intrathoracic, intraperitoneal 3 >26 points =78%or aortic operation

9. Aortic stenosis 3

Detsky modified multifactorial index 4

1. Class 4 angina 20

2. Suspected critical aortic stenosis 20

3. Myocardial infarction within 106 months

4. Alveolar pulmonary edema 10within 1 week

5. Unstable angina within 3 months 10

6. Class 3 angina 10

7. Emergency operation 10

8. Myocardial infarction more 5than 6 months ago

9. Alveolar pulmonary edema 5 Cardiac complica-resolved more than 1 week ago tion rate:

10. Rhythm other than sinus or 5PACs on EKG

11. More than 5 premature 5 > 15: high riskventricular contractions (PVC)any time before surgery

12. 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 fornon-invasive test

4. Q waves on ECG 1

5. Ventricular arrhythmias 1 >3: send forangiography

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

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agement depends upon various clinical risk factors andsurgery specific risk factors3.

Clinical risk factorsObtained by history, physical examination &review of

ECG, the clinical risk factors are grouped into 3 categories-

1. Major clinical predictors are unstable coronary syn-drome, decompensated heart failure, significantdysrrhythmia 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 are mild angina pecto-ris, previous MI by history or pathological Q waves,compensated or prior heart failure, insulin dependentdiabetes mellitus,and renal insufficiency. These aremarkers of enhanced risk of peri-operative cardiaccomplications. It appears reasonable to wait for 4-6weeks 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 factors1. 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 anticipatedblood loss) are often reported to have a cardiac riskof greater than 5%.

2. Intermediate risk surgeries- (carotid endarter-ectomy, head and neck surgery, intraperitoneal andintrathoracic surgery, prostate surgery) are reportedgenerally to have cardiac risk of less than 5%.

3. Low risk procedures:- (endoscopic procedures, su-perficial procedures, cataract surgeries, breast surgery)are reported to have less than 1% risk of cardiac events.

Preoperative managementAt risk patients need to be managed with pharmaco-

logic and other perioperative interventions that can ame-liorate perioperative cardiac events . Three therapeuticoptions 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 blockershave been shown to be useful in reducing perioperativemorbidity and mortality in high risk cardiac patients andpreferably titrated to a heart rate of 50 to 60 bpm7. 2

agonists by virtue of their sympatholytic effects can beuseful in patients where beta blockers are contraindicated.Nitroglycerine lowers LVEDP by reducing preload . Itimproves collateral coronary flow and reduce systemicB.P. Other agents like calcium channel blockers , ACEinhibitors, aspirin, insulin, statins prove to be beneficialperioperatively.

Coronary intervention should be guided by patient’scardiac condition( unstable angina, left main or equivalentCAD, three vessel disease,decreased LV function) andby the potential consequences of delaying the noncardiacsurgery for recovery after coronary revascularization3

.Patients who underwent PCI had better outcome afternoncardiac 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 reducechance of bleeding. Continuing the therapy can lead tosignificant postoperative bleeding. Discontinuing or modi-fyinganti-platelet therapyshould involve a multidisciplinaryteam of cardiologist, surgeon, anaesthesiologist 8 .

Preanaesthetic considerationsPreoperative visit to the patient is very important.A

good rapport should be made with the patient and writtenconsent obtained. Patient should be explained about therisk of surgery and anaesthesia.It is important to continuethe medications till the day of surgery like betablockers,calciumchannel blocker ,digitalis.Potassium levelshould be normal as hypokalemia can cause digitalis tox-icity.Anticoagulants should be stopped.

PremedicationSignificance of premedication in allaying anxiety in

cardiac patients is of paramount importance. This is toprevent increase in B.P. and HR which can disturb themyocardial oxygen supply and demand and can induceischaemia. Any combination of benzodiazepine likelorazepam and opioid like morphine should be given onehour prior to arrival in operation theatre.

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The following algorithm helps in easy reference for planning perioperative management of cardiac patientsundergoing noncardiac surgery.

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Intraoperative managementMonitoring

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. Monitoringthree ECG leads ( II,V4,V5 or V3,V4,V5 ) improves rec-ognition of ischaemia. The ST segment trending systemalso helps in the detection of ischaemia ii. Blood pressureiii. Pulse oximetry iv. Capnography v. Temperature moni-toring vi. Urine output monitoring 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 forroutine use 9.

Choice of anaesthetics

The anaesthesiologist should select the drugs withthe objective of minimizingdemand and optimumsupply ofoxygen. Along with the anaesthetic agent some cardiacdrugs should be readily available to maintainhaemodynamics, to prevent & treat ischaemia, if it occurs.

General anaesthesia

1. Intravenous anaestheticsThiopentone—It reduces myocardial contractil-

ity, preload and blood pressure and there is slight in-crease in heart rate. It should be administered slowlyand 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 goodventricular function but is not good induction agent forpatients with CAD.

Ketamine-—It is not good in IHD and valvular heartdisease patients.It is however a useful agent in situationslike 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 haemodynamicchanges. It is excellent for induction in patients with poorcardiac reserve.

2. Narcotics—Morphine is the preferred drug forits relative cardiac stability and very good analgesiceffect.It produces arterial and venous dilatation ,resultingin reduction of afterload and preload.Newer narcotic an-algesic agents like fentanyl, alfentanyl and sufentanil alsoprovide adequate cardiac stability and pain relief.

3. Inhalational agents- Isoflurane is recommendedin patients with good myocardial contractility. Halothanehas the disadvantage of myocardial depression and po-tential of dysrrhythmias.

4. Nitrous oxide —It provides stable haemodynamicsin 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 depolarizingmuscle relaxants without any significant cardiovascularside effects.

6. Glycopyrrolate—It is preferred over atropinesince it produces less tachycardia & should be used onlyif specifically required.

Regional anaesthesiaThe 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 includehypotension from uncontrolled sympathetic blockade andneed for volume loading can result in ischemia. Careshould be taken while giving local anaesthetic becauselarger doses can cause myocardial toxicity and myocar-dial depression. Use of epinephrine with local anaestheticis not recommended10.

Managing intraoperative complications1) Intraoperative ischaemia

1 If patient is haemodynamically stable—

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

I/V Nitroglycerine

Heparin after consultation with surgeon

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2 If patient is haemodynamically unstable-

Support with inotropes

Use of intraoperative ballon pump may be nec-essary

Urgent consultation with cardiologist to plan forearliest possible cardiac catheterization

2) Other complications like dysrrhythmias, pacemakerdysfunction should be managed accordingly

Post operative managementGoals are same as intraoperative

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

Although most cardiac events occur within first 48hours, delayed cardiac events (within first 30 days ) stillhappen and could be the result of secondary stress. Postoperative stress of extubation, pain, sepsis, haemorrhage,anaemia, respiratory problems can increase the demandon the heart and should be minimized and treated.

Valvular heart diseasesPatients with valvular heart diseases coming for

surgery present many challenges to the anaesthesiologist.Now it is no longer necessary or even advisable to delaysurgery until advanced symptoms are present. Valvularsurgery is advised in such patients before elective non-cardiac surgery. The perioperative physician has to beaware of the varying effects of haemodynamic variableson this sub population of patients. The five variables indealing 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 anaesthetictechnique can be chosen with a view to maintain optimalcardiac performance. In general ,the goal in stenotic le-sions is to enhance forward flow , where as in regurgitantlesions is to decrease regurgitant flow . All the patientswith valvular heart disease undergoing non-cardiac sur-gery should get antibiotic prophylaxis to prevent infectiveendocarditis.AHArecommends ampicillin, 2 g I.M or I.Vplus gentamicin 1.5 mg.kg-1 I.M or I.V 30 min. beforeprocedure and 6 hrs later ampicillin 1 gm I.M or I.V. Forpatients allergic to penicillin, vancomycin 1 gm I.V is rec-ommended. For dental and endoscopic procedures, oralamoxicillin 2gm or cephalexin 2 gm or azithromycin 500mg ,1 hr. before the procedure is given. Use of oral anti-

coagulants in patients with mitral stenosis who have atrialfibrillation 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 andmild vasodilatation to decrease the amount of regurgitantflow. In AS consideration should be given to the possibil-ity of CAD 11

HypertensionHypertension is the commonest cardiac disease all

over the world. These patients are documented to haveassociated CAD, left ventricular dysfunction, renal failurewhich increase the perioperative risk. Hence it is advisableto 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 continue antihypertensives till the dayof surgery. For patients with marked elevations of BP intraor post operatively should be managed by either nitroglyc-erine or sodiumnitroprusside by I.V. infusion. IntraarterialB.P. monitoring is recommended for such patients. Anyfactors of sympathetic stimulus should be avoided.

DysrrhythmiasDysrrhythmias may be a marker of severity of un-

derlying CAD 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 treatedby 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 onpermanent pace makers ,electro cautery should be usedwith 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 overviewof the guidelines, which will continue changing from timeto time, depending upon the evidence procured over aperiod of time. Also the techniques need to be tailoredvarying from patient to patient, surgical needs and thefacilities available.

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2. Goldman L,Caldera D,Nussbaum S, et al. Multifactorial index ofcardiac risk in noncardiac surgical procedures. N Engl J Med1977;297:845.

3. Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guidelineupdate for perioperative cardiovascular evaluation for noncar-diac surgery-executive summary. A report of the American Col-lege of Cardiology / American Heart Association Task Force onPractice Guidelines (Committee to update the 1996 guidelineson Perioperative Cardiovascular Evaluation for Noncardiac Sur-gery). Anesth Analg 2002; 94:1052.

4. Detsky AS, Abrams HB, Forbath N , et al. Cardiac assessmentfor 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 forperioperative 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:StoeltingRK, 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 withcoronary artery stent : what should the anaesthesiologist know? Can J Anaesth 2005;52:356.

9. Barash PG.Sequential monitoring of myocardial ischemia in theperioperative period.In: American Society ofAnaesthesiologistsReview Lectures.Atlanta: American Society ofAnaesthesiology;2005.p.411.

10. Breen P, Park K W. General anesthesia versus regional anesthe-sia. Int Anesthesiol Clin 2002; 40:61.

11. Bonow RO, Carabello B, de Leon AC Jr, et al. Guidelines for themanagement of patients with valvular heart disease: Executivesummary: 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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Anaesthetic considerations in cardiac patients undergoing non