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Anaesthesia and heart failure

Introduction:

Congestive cardiac failure (CCF) is a common and debilitating condition. It is characterised by impaired ventricular performance resulting in fatigue, exercise intolerance, an increased incidence of ventricular arrhythmias and a shortened life expectancy.

The three major risk factors for the development of heart failure are age, hypertension and coronary artery disease. Perioperatively, heart failure is associated with a substantial increase in morbidity and mortality.

Characteristically the chambers of the heart become enlarged, with increased wall thickness and stiffness. Underlying this is a process of fibrosis and myocellular hypertrophy. These morphological changes lead to important functional changes which affect both diastole and systole.

Timing of surgery

The correct timing of elective non-cardiac surgery is important to decrease patient risk.

The ACC/AHA guidelines identify decompensated or untreated heart failure as a major clinical predictor of risk. Where possible, surgery should be postponed for the purpose of medical therapy, modification of risk factors and further investigations (including coronary angiography, if appropriate).

Compensated heart failure, or a history thereof, represents an intermediate clinical predictor.

Low-risk surgical procedures can safely continue, but formal assessment of the patient’s functional capacity should be considered if intermediate risk or vascular surgery is planned.

Anaesthetic implications:

The anaesthetic management of patients with heart failure depends on (i) the degree of heart failure, (ii) the cause and nature of the cardiomyopathy and (iii) the surgical procedure.

Pre-op assessment

It is important that patients with congestive cardiac failure are identified preoperatively, especially those with evidence of current or recent decompensation. Evidence of decompensation within 6 months of surgery is associated with increased risk. There may be a history of shortness of breath and reduced exercise tolerance. Associated co-morbidity such as

ischaemic heart disease, hypertension and diabetes should be sought. Examination may reveal peripheral or pulmonary oedema and a third heart sound

Investigations

Blood tests:

Anaemia and electrolyte disturbance (especially for patients taking diuretics) should be identified and treated. Other blood tests which may reveal aggravating factors include liver and thyroid function tests and blood glucose estimation.

ECG:

A normal ECG is very unusual in patients with heart failure, and should prompt review of the diagnosis. Three key ECG findings are chamber hypertrophy, ventricular strain patterns and signs of ischaemia or previous infarction. Atrial fibrillation is also common in heart failure patients.

CXR:

Signs may include cardiomegaly, pleural effusions, prominent upper lobe veins (upper lobe diversion), engorged peripheral lymphatics and alveolar oedema.

Echocardiogram:

This is the most useful test and can provide important anatomical information as well as an assessment of function. Heart failure can be secondary to valvular disease (usually aortic stenosis or mitral regurgitation).

Patients with an ejection fraction of less than 40% are considered to have systolic failure and those with an ejection fraction of less than 30% have severe disease. An echocardiogram provides measurements of both systolic and diastolic function. The left ventricular ejection fraction (LVEF) is the most commonly used measure of systolic function. An LVEF >50% is regarded as good, ................
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