Electrocardiography ECG

This is a routine investigation. It is inexpensive and noninvasive. The standard I2-lcad ECG (Fig. 3.36.) comprises

Fig. 3.35 Transoesophageal echocardiography in a 4 chamber view.

There is a large vegetation attached to the atrial aspect of the tricuspid valve, LA a left atrium, RA = right atrium, LV = left ventricle, RV = right ventricle, VEG = vegetation.

Fi g. 3.36 Electrocardiogra phy. Diagram to show the directions from which the 12 standard leads 'look at' the heart. The transverse section is viewed from below like a CT scan.

TABLE 3.29 Common cardiac investigations

Investigation

Indications

Implications

ECG

Numerous (medical and medico-legal)

Confirms the cardiac rhythm and reveals abnormalities in conditions such as LBBB and W.P.W, syndrome

Diagnosis of myocardial infarction

Assessing abnormalities in left ventricular hypertrophy. May reveal Ischaemia: however usually normal in patients with angina

Exercise ECG

Chest pain

Ischaemic changes during exercise, especially when associated with symptoms, support a diagnosis of angina.

However, exercise test can be normal in angina patients (false negative) and abnormal In healthy individuals (false positive)

Post-myocardial infarction

Provides prognostic Information

Ambulatory ECG monitoring

Palpitations

Confirms whether patients' symptoms are coincident with cardiac arrhythmia, e.g. ventricular ectopic beats or atrial fibrillation

Syncope or presyncope

May show intermittent bradycardia or tachyarrhythmia if symptoms occur during monitoring

Chest X-ray

Numerous

Cardiothoracic ratio: maximum width of the cardiac sllhouette/wldest part of lung fields, usually the base.

Increased in heart failure and valve disease Pulmonary oedema in heart failure

Echocardiography

Cardiac murmur

Stenotic valve lesion readily diagnosed and accurately quantified Regurgitation readily detected with semi-quantitative assessment

Breathlessness

Left ventricular function can be assessed. Impaired in heart failure

Infective endocarditis

Valve vegetations confirm the diagnosis. Transoesophageal echo is more sensitive

Radionuclide studies

Breathlessness

Blood pool scanning provides an accurate assessment of left ventricular function, usually expressed as ejection fraction (end diastolic volume - end systolic volume/end diastolic volume)

Chest pain

Myocardial perfusion scan reveals ischaemic deficits In ischaemic heart disease

Pulmonary embolism

Lung scan shows a perfusion deficit. Usually compared with simultaneous ventilation scan

Cardiac cathetehsation

Angina

Coronary angiography reveals the extent and severity of coronary stenoses. This determines the therapeutic approach

Valve disease

Better evaluated non-invasively by echocardiography. Cardiac cathetensation Is only indicated to assess the coronary anatomy in patients who require heart valve surgery

Heart failure

Right heart catheterlsatlon in patients with severe heart failure helps determine suitability for cardiac transplantation

unless it is recorded during ail attack. Patients are therefore exercised on a treadmill or a stationary bicycle and if the symptoms induced are due to angina changes are usually visible on the ECG. The severity of the changes induced, and the degree of exercise required to produce them, may be of prognostic significance.

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