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Preoperative Assessment of the Cardiac Patient for Non-cardiac Surgery

John R. Butterly, M.D.

Issues Overview of ischemic

heart disease General

considerations– Anesthetic

– Operative

Clinical assessment

Predictors of risk– Clinical

– Procedural

Disease specific states– CAD, hypertension,

CHF, valvular

Preoperative therapy

Bottom Line

Indications for evaluation/intervention are the same as in the general population

Pre-operative evaluation should be seen as an opportunity to provide recommendations for care over the long-term as well as the immediate, peri-operative period

Intervention is rarely necessary to lower the risk of non-cardiac surgery

Overview of Ischemic Heart Disease

Anatomy Physiology

– coronary– left ventricular– patient

Etiology of Ischemia

Supply– blood O2 carrying capacity

– cardiac output

– systemic vascular resistance

– coronary resistance (Poiseuille)

Demand– Major determinants of MVO2

» systolic work heart rate blood pressure (afterload) duration of systole

» ventricular wall tension (LaPlace)

» contractility

» myocardial mass

coronary resistance ~ 1/R4 T = PR

Ischemia vs Infarction

Implications of demand related problem vs supply related problem– stability– biology

» endothelial function

» plaque rupture/thrombosis

General Considerations

A substantial proportion of all deaths in most series of non-cardiac operations arise from cardiovascular complications.

Stresses to cardiovascular system– decrease in myocardial contractility & respiration– fluctuations in temperature, afterload, preload, blood

volume, & autonomic nervous system output

General Considerations

Possible complications of anesthesia & surgery may impose additional burdens– hemorrhage– infection– pulmonary embolism– myocardial infarction

Anesthetic Considerations

Factors influencing cardiovascular function– direct effect of anesthetic agent on heart– indirect effects mediated through the

autonomic nervous system– level of ventilation

» hypoxia

» hypercarbia

» acidosis

Anesthetic Agents

General– inhalation

– intravenous

– muscle relaxants

Spinal/Epidural– hemodynamic

consideration

The skill & experience of the anesthesiologist, including the ability to monitor hemodynamics & respond quickly, are far more important than the specific agent used.

Case Study Fragilina Moribundi is a 93 yo, pleasantly demented

woman who presents to your office speaking fluent diabinase. She is referred for pre-operative cardiac evaluation prior to her planned cataract surgery.

She has a history of a systolic murmur, and is s/p IMI in the distant past.

Her history is contributory only in the absence of sx’s suggestive of active ischemia or LV dysfunction

Her exam is remarkable for findings c/w severe aortic stenosis

Her EKG shows findings c/w OIMI

Case Study Appropriate actions/evaluation would include

– stress testing with imaging to risk stratify and rule out active ischemia

– echocardiography to evaluate the severity of the aortic stenosis and baseline LV function

– cardiac catheterization with an eye towards balloon valvuloplasty, if severe aortic stenosis is confirmed, as a bridge to get her through the proposed surgery

– a discussion with the PCP re: the indications for the proposed surgery, and clearance for same with appropriate precautions

Case Study Mrs. Moribundi does well with her cataract extraction, but

2 months later presents to the ER with evidence for total bowel obstruction and free air under the diaphragm. You are emergently consulted by the general surgeons who want to take her to the OR.

Appropriate actions include:– emergency echocardiogram to evaluate status of valve and

ventricle

– trip to the cath lab for emergency balloon valvuloplasty

ventricle

– trip to the cath lab for IABP placement prior to surgery

ventricle

– trip to the cath lab for IABP placement prior to surgery

– discussion with anesthesia re: optimal peri-operative management/hemodynamic monitoring

The Operation Type

– in general, surgical mortality is 25-50% higher in patients with underlying cardiovascular conditions compared to patients with normal cardiac function.

– ophthalmologic surgery & TURP almost always safe– highest cardiovascular complication rates seen in

vascular surgery» AAA

aortic cross-clamping, major fluid & electrolyte shifts

» carotid / peripheral surgery co-existing CAD, clinical underestimation of severity

The Operation

Duration– correlation is general and mostly related to type

of operation– exceptions

» operative time prolonged due to complication

» operation > 5 hours

Cardiac Risk for Noncardiac Surgical Procedures

High (reported cardiac risk > 5%)– emergent major operations, esp. in elderly– aortic and other major vascular procedures– peripheral vascular procedures– anticipated prolonged procedure with large

fluid shift/blood loss

Intermediate (reported cardiac risk < 5%)– carotid endarterectomy– head and neck– intraperitoneal & intrathoracic– orthopedic– prostate

Low (reported cardiac risk < 1%)– endoscopic procedures– superficial procedure– cataract– breast

Case Study

Mr. A. Jean Jacques is a 58 year old gentleman referred for pre-operative evaluation because of one isolated PVC seen on a pre-op EKG. He is scheduled for nephrectomy for a renal mass the following morning He has no cardiac history of which he is aware. His only risk factor is that of a history of 3 years of smoking in college.

Case Study

He considers himself fit, and is proud of being in good physical condition. He plays full court basketball on Saturdays, and wins. He climbed Mount Washington in October and was pleased that a few of his sons friends could not keep up with him. He denies dyspnea or chest discomfort, and his exam is remarkable in that he looks fit and has a resting pulse of 52 on no medications.

Case Study

Appropriate next steps include– routine stress testing to risk stratify and rule out

occult ischemia

Case Study

Appropriate next steps include– routine stress testing to risk stratify and rule out occult

ischemia

– 24 hour Holter monitor to evaluate burden of ventricular ectopy

Case Study

ischemia

– echocardiogram to rule out unsuspected LV dysfunction

Case Study

ischemia

– echocardiogram to rule out unsuspected LV dysfunction

– clear for surgery with no recommendations for further cardiac evaluation

Clinical Assessment

History– Single most important part of evaluation to

determine level of cardiovascular risk» Identify presence of cardiac condition

» Evaluate severity, stability

» Identify risk factors, co-morbid conditions

» Determination of individual functional capacity

Taking a history for angina

The asymptomatic patient

Silent ischemia– “active” silent ischemia

» Type I - absence of any sx despite the presence of CAD & provocable ischemia (defective anginal warning system)

» Type II - sx’s generally present, but patient also has silent episodes

– “passive” silent ischemia» sedentary patient» patient limited for other reasons

Functional Capacity

1 MET– Can you take care of self?

– Eat, dress, use toilet?

– Walk indoors in house?

– Walk a block or two on level at 2-3 mph?

– Do light housework like dusting or dishes?

4 METs

4 METs– Climb a flight of stairs, walk up

– Walk on level at 4 mph?

– Run a short distance?

– Heavy housework

– Golf, bowling, dancing, doubles tennis

– Swimming, singles tennis football, basketball, skiing

>10 METs

Clinical Assessment

Physical examination– general appearance– evidence for CHF– evidence for PVD– heart sounds, murmur

Clinical Assessment

Co-morbid conditions– pulmonary– diabetes mellitus *– renal impairment– hematologic disorders

Clinical Assessment

Ancillary studies– CBC, PT/PTT, blood chemistry (electrolytes, BUN,

creatinine)– ECG– CXR ??

Case Study Alvin Falfa is a 63 yo dairy farmer from the Northeast

Kingdom. He was discharged from North Country Hospital 3 weeks ago having sustained an uncomplicated, non-Q MI. He has been slowly increasing his activity and is asx. He was incidently found to have an iron deficiency anemia during his hospitalization, and this was felt to be the cause of his MI. Further w/u revealed a large, fungating mass in his cecum, biopsy positive for adenoCa. He is referred for pre-op evaluation prior to his right hemicolectomy which is scheduled for tomorrow morning.

Case Study Initial appropriate actions include:

– postponement of the scheduled surgery

– stress testing for risk stratification and to determine whether or not there is inducible ischemia

– echocardiography to evaluate LV function

– cardiac catheterization with an eye towards intervention prior to abdominal surgery

– clearance for surgery after a discussion with anesthesia about appropriate peri-operative management/hemodynamic monitoring

Clinical Predictors of Risk Major

– Unstable coronary syndromes» recent MI with evidence for ischemia

» unstable or severe angina (Canadian class III or IV)

– Decompensated CHF– Significant arrhythmia

» high grade AV block

» symptomatic ventricular arrhythmia (with organic disease)

» supraventricular arrhythmia with uncontrolled rate

– Severe valvular disease

Clinical Predictors of Risk

Intermediate– Mild angina pectoris (Canadian class I or II)– Prior MI by history or pathological Q waves– Compensated or prior CHF– Diabetes mellitus– Renal insufficiency (creatinine > 2)

Clinical Predictors of Risk

Minor– Advanced age– abnormal ECG (LVH, LBBB, ST-T change)– Rhythm other than sinus– Low functional capacity– History of stroke– Uncontrolled systemic hypertension

Determination of need for further cardiac testing

Urgency of surgery

Recent revascularization

Recent coronary evaluation

Major predictor of risk

Intermediate predictor of risk– functional capacity

– risk level of surgery

Minor or no predictor of risk– functional capacity

– risk level of surgery

Disease-Specific Approaches

Coronary Artery Disease Hypertension Congestive Heart Failure/Cardiomyopathy Valvular Heart Disease Arrhythmias & Conduction Defects Pulmonary Vascular Disease

Case Study

Hiram Wrisck is a 72 yo gentleman referred for evaluation prior to AAA. He describes himself as active, but his wife rolls her eyes behind his back when he says this. He has a positive history of hypertension and adult onset diabetes that recently became insulin dependent, but no history to suggest angina. A stress test done prior to his visit with you demonstrated 1.5mm ST depression in leads II, V4-6 at 4 METS (100 bpm)

Case Study

Physical exam shows him to be an obese 72 year old man looking older than his stated age. He weighs 285#, pulse is 96 with frequent extra-systoles, BP 140/90 in right arm, 190/105 in left arm. The rest of the exam is remarkable for a II/VI SEM at the LSB, bilateral carotid and femoral bruits, and absent pedal pulses.

Case Study

Appropriate next steps include– Repeat stress as a DSE to try to get a heart rate

response closer to 85% PMHR

Case Study

– Cardiac catheterization with a low threshold for percutaneous or surgical revascularization if anatomically appropriate

Case Study

– Recommend intra-operative SG line and i.v. TNG

Case Study

– Recommend intra-operative SG line and i.v. TNG

– Fully review the medical record in hopes that Andy Torkelson has previously seen him at some point in time

Coronary Artery Disease

Clinically apparent vs occult disease– past history– active symptoms– “active” vs “passive” silent ischemia

Issues to be addressed– ischemic threshold– amount of myocardium in jeopardy– left ventricular function

Coronary Artery Disease Risk assessment based on stress testing

High risk– ischemia induced at low level (< 4 METs, heart

rate < 100 or < 70% age predicted) with:» ST depression > 0.1 mV

» ST elevation > 0.1 mV in noninfarct lead

» five or more abnormal leads

» persistent ischemic response > 3 minutes post exercise

» typical angina

– thallium

Intermediate risk– ischemia induced at moderate level (4-6 METs,

heart rate 100-130 or 70-85% age predicted with:» ST depression > 0.1 mV

» typical angina

» persistent ischemic response >1-3 minutes post exercise

» three to four abnormal leads

Low risk– no ischemia or ischemia at high level (> 7 METs,

heart rate > 130 or >85% age predicted with:» ST depression > 0.1 mV

» typical angina

» one to two abnormal leads

Coronary Artery Disease Indications for Coronary Angiography Class I: patients with suspected or proven CAD

» high risk results from noninvasive testing

» angina pectoris refractory to medical therapy

» unstable angina

» nondiagnostic/equivocal test results in high risk pt.

Class II:» intermediate risk results from noninvasive testing

» nondiagnostic/equivocal test results in intermediate risk pt.

» urgent non-cardiac surgery in convalescent period post-MI

» perioperative MI

Coronary Artery Disease Indications for Coronary Angiography

Class III:» low risk surgery in pt. with known CAD & low risk testing

» screening for CAD

» asx pt. after revascularization with exercise capacity > 7 METs

» mild, stable angina with good LV function, low risk testing

» patient not candidate for revascularization

Other disease states

Hypertension– not independent risk factor– implications for intraoperative lability– rational for preoperative control

Congestive heart failure/Cardiomyopathy– confers risk independently– etiology key to risk assessment/treatment

Congestive Heart Failure/Cardiomyopathy» systolic vs diastolic dysfunction

» hypertrophic cardiomyopathy

Valvular heart disease» aortic stenosis

» mitral stenosis

» regurgitant (volume overload) lesions

» antibiotic prophylaxis / anticoagulation

Arrhythmias & conduction defects» important as markers for underlying disease

» therapy aimed to correct or avoid ischemia or hemodynamic embarrassment

» high grade AV block - to pace or not to pace

Pulmonary vascular disease» little objective data available

» sensitivity to hypoxia

» implication in presence of pre-existing shunts

Supplemental Preoperative Evaluation

Resting left ventricular function» methodology

» when is it good to be over 40?

» indications for testing

Stress testing» exercise

» nonexercise persantine thallium dobutamine stress echocardiography

Preoperative TherapySurgical revascularization

CASS registry Foster et al Ann Thorac Surg 1986;41:42-50 » 1600 pts. underwent noncardiac operations , 113 (7%) vascular

» mortality rates 0.5% without angiographic evidence advanced CAD 0.9% with prior CABG 2.4% with significant CAD (70% stenosis) but no prior revascularization

European Coronary Surgery Study Group Lancet 1982;2:1173-80

» survival rates, 58 pts. with PVD randomized to CABG or medical Rx 85% with CABG 57% with medical Rx

p=.009

Cleveland Clinic series Ann Surg. 1984;199:223-233

» 1001 pts. scheduled for elective vascular surgery

» mortality rates 5.3% + 1.5% for CABG group (6.8%) 1.4% in group with normal coronaries 1.8% in group with mild to moderate CAD 3.6% in group with advanced, compensated CAD 14% in group with severe, uncorrected CAD

» 5 year survival 72% in pts. who underwent CABG 43% in pts. in whom CABG indicated but not performed

p=.001

Indications for preoperative CABG– left main stenosis with acceptable risk– 3VD with LV dysfunction– 2VD with severe, proximal LAD disease– coronary ischemia refractory to medical

management

ACC/AHA Task Force JACC 1991;17:543-589

Preoperative TherapyCatheter based revascularization

Mayo Clinic series Mayo Clin Proc. 1992;67:15-21

» 50 pt. series, high risk group 10% required urgent CABG perioperative MI rate 5.6% mortality rate 1.9%

Timing» restenosis

» recoil/thrombosis

New technologies

Preoperative TherapyMedical therapy

Author Procedure n Control Drug Ischemiacontrol/drug

MIcontrol/drug

CoriatAnesth 1984

carotid 45 TNG 0.5mcg/kg/m

TNG 1.0mcg/kg/m

64%/17% 0/0

DoddsAnesth Analg

noncardiac 45 placebo TNG 0.9mcg/kg/m

32%/30% 4%/0%

GodetAnesth 1987

vascular 30 placebo diltiazem3mcg/kg/m

73%/4% 0/0

PasternakCirc 1987

AAA 83 case-control

metoprolol50 mg p.o.

_____ 18%/3%

PasternakAm J Surg

vascular 200 unblinded metoprolol50 mg p.o.

2.4/5episodes

StoneAnesth 1988

noncardiac 128 placebo p.o. betablocker

28%/2% 0/0

Preoperative Therapy

Valve surgery» general considerations

» balloon valvuloplasty

» stenotic vs regurgitant lesions

Arrhythmia/Conduction Devices» ICD’s

» pacemakers

Tools Vs Toys

Pulmonary artery catheters

Transesophageal echocardiography

Intra-aortic balloon counterpulsation

Summary Overview of ischemic

heart disease General

considerations– Anesthetic

– Operative

Clinical assessment

Predictors of risk– Clinical

– Procedural

Disease specific states– CAD, hypertension,

CHF, valvular

Preoperative therapy

Conclusions

Judgement/Experience/Skill

Medical care: a point in time vs continuum

Teamwork

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