Page 39 - Medicine and Surgery

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Chapter 2: Ischaemic heart disease 35

I aVR V1 V4

II aVL V2 V5

III aVF V3 V6

Figure 2.4 Exercise test. The figure shows a cardiac cycle from each lead taken at rest (left) and during exercise (right). In this
example exercise results in widespread ST depression (ischaemic changes) in the inferior (II, III, aVF) and anterolateral chest leads
(V2–V6).

Symptomatic treatment may involve one or a combi- careinconjunctionwithβ-blockersorinpatientswith
nation of the following: heart failure.
β-blockers reduce the oxygen demand of the heart by Potassium channel openers such as nicorandil are

reducing the heart rate and the force of ventricular third line agents.
contraction. They are particularly useful after a my- If symptoms cannot be controlled by medication, the
ocardial infarction to reduce the risk of a subsequent main choices for coronary intervention are between
cardiac event. coronary angioplasty (see page 28) and coronary artery
Longactingnitrates(oralortranscutaneous)arecoro- bypass surgery (see page 29).

nary artery dilators and are useful in patients who re- Coronary artery bypass grafting is indicated where it
spond to sublingual GTN. may improve prognosis or when symptoms persist to
Calcium channel blockers such as diltiazem and am- an extent that interferes with normal life despite med-

lodipine reduce coronary artery tone. Diltiazem and ical treatment. In patients with triple vessel disease or
verapamil also reduce the heart rate and the force of left main stem coronary artery disease, surgery im-
ventricular contraction resulting in a decreased my- proves outcome. Operative mortality depends on sev-
ocardial oxygen demand. They should be used with eral factors including age and concomitant disease.