Anaesthesia and cardiac risk factors

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Anaesthesia and cardiac risk factors

Overview

Epidemiology

· prevalence of cardiovascular disease increases progressively with advancing age.

· number of patients over 65 years of age is expected to increase by 25–35% over the next two decades.

Common co-morbidity with preexisting cardiovascular disease

· Perioperative myocardial infarction (MI),

· pulmonary edema,

· congestive heart failure,

· Arrhythmias

· Thromboembolism

Incidence of cardiovascular complications

Death

· 25–50% of deaths following non-cardiac surgery.

Postoperative cardiogenic pulmonary edema

· 2% in all patients over 40 years

· 6% in patients with a history of heart failure and

· 16% in patients with poorly compensated heart failure.

Importance of Cardiac risk

· The relatively high prevalence of cardiovascular disorders in surgical patients has given rise to attempts to define cardiac risk or the likelihood of intraoperative or postoperative fatal or life-threatening cardiac complications.

· An American College of Cardiology/American Heart Association Task Force Report has divided clinical markers of increased cardiovascular risk into major, intermediate, and minor predictors (Table 20–1).

Cardiac risk and its respective management

Overview

· Major predictors mandate intensive management,

· Intermediate predictors are markers of enhanced risk and require careful preoperative assessment,

· Minor predictors are recognized markers of cardiovascular disease that have not clearly been shown to independently increase perioperative risk.

Management in patient with major predictors

· should undergo noninvasive cardiac evaluation and, when appropriate coronary angiography.

Management in patients with intermediate predictors and minor predictors

· Comprise of majority of patients

Major

· Unstable coronary syndromes

· Acute or recent MI3 with evidence of important ischemic risk by clinical symptoms or noninvasive study

· Unstable or severe4 angina (Canadian class III and IV)5

· Decompensated heart failure

· Significant arrhythmias

· High-grade atrioventricular block

· Symptomatic ventricular arrhythmias in the presence of underlying heart disease

· Supraventricular arrhythmias with uncontrolled ventricular rate

· Severe valvular disease

Intermediate

· Mild angina pectoris (Canadian class I or II)

· Previous MI by history or pathological Q waves

· Compensated or prior heart failure

· Diabetes mellitus (particularly insulin dependent)

· Renal insufficiency

Minor

· Advanced age

· Abnormal ECG (left ventricular hypertrophy, left bundle-branch block, ST-T abnormalities)

· Rhythm other than sinus (eg, atrial fibrillation)

· Low functional capacity (eg, inability to climb one flight of stairs with a bag of groceries)

· History of stroke

· Uncontrolled systemic hypertension

1. Intermediate clinical predictors are present · Canadian class I or II angina, · prior MI based on history or pathological Q waves, · compensated or prior heart failure · diabetes

2. Poor functional capacity · less than 4 METs

3. High surgical risk procedure · emergency major operations3; · aortic repair or peripheral vascular surgery; · prolonged surgical procedures with large fluid shifts or blood loss)

Cardiac risk factors

· The two most important preoperative risk factors are an unstable coronary syndrome and evidence of congestive heart failure.

· Identifying patients at greatest risk allows appropriate measures to be taken that may alter the outcome favorably.

· Indeed, some studies suggest that a lower complication rate is achieved when invasive monitoring and aggressive hemodynamic interventions (eg, vasodilators, adrenergic blockade) are employed for patients at high risk for cardiac complications.

Contraindication to elective non-cardiac surgery

· MI less than 1 month prior to surgery

· MI with evidence of persistent ischemic risk by symptoms or noninvasive

Overview

· Most important intraoperative risk factors

· urgency of surgery

· operative site.

Incidence

Urgency

· two to five times more likely for emergency surgery.

Site

· major thoracic, abdominal, and vascular operations.

· Cardiovascular risks for carotid artery surgery appear to be less than for aortic and infrainguinal arterial bypass surgery

Vascular operations

· Vascular operations, particularly infrainguinal bypass procedures, represent particularly high-risk procedures

· Reason- peripheral vascular disease and coronary artery disease (CAD) share common risk factors (eg, diabetes, history of smoking, hyperlipidemia, and advanced age);

Ambulisation and cardiac risk factors

· symptoms of CAD are obscured by limits to activity due to claudication and by the nature of the procedures, which may be prolonged and often associated with significant blood loss.

Hemodynamic  

· poorly controlled hypertension is not clearly established as a risk factor for postoperative complications,

· poorly controlled hypertension frequently associated with wide intraoperative swings in blood pressure.

· intraoperative hypertension has been more closely linked to cardiac morbidity than hypotension

Cardiac Risk¹ Stratification for Noncardiac Surgical Procedures.²

High 

(reported cardiac risk often greater than 5%)

· Emergent major operations, particularly in the elderly

· Aortic and other major vascular surgery

· Peripheral vascular surgery

· Anticipated prolonged surgical procedures associated with large fluid shifts and/or blood loss

Intermediate 

(reported cardiac risk generally less than 5%)

· Carotid endarterectomy

· Head and neck surgery

· Intraperitoneal and intrathoracic surgery

· Orthopedic surgery

· Prostate surgery

Low³ 

(reported cardiac risk generally less than 1%)

· Endoscopic procedures

· Superficial procedure

· Cataract surgery

· Breast surgery

¹Combined incidence of cardiac death and nonfatal myocardial infarction.

²ACC/AHA Guideline Update on Perioperative Cardiovascular Evaluation for Noncardiac Surgery.

³Do not generally require further preoperative cardiac testing

Choice of anaesthesia

· Although the superiority of regional anesthesia over general anesthesia for patients with cardiovascular disease might seem obvious, studies supporting this view are lacking.

· Moreover, the hemodynamic effects of spinal and epidural anesthesia  may be more detrimental than well-managed general anesthesia for some patients.