Ischaemic heart disease

Ischaemic heart disease (IHD) is an umbrella term for all conditions characterised by ischaemia of the myocardium. Because this is almost always due to coronary artery atherosclerosis, the term coronary artery disease (CAD) is virtually equivalent to IHD and they’re often used interchangeably.

Diagnosis and evaluation

Cardiac CT can be useful in the evaluation of ischaemic heart disease. Coronary CT angiography is a non-invasive alternative to invasive coronary angiography, used for the diagnosis of coronary artery disease in those at low or intermediate pretest probability. Those with high pretest probability proceed directly to invasive coronary angiography, as this allows for percutaneous coronary intervention of any stenoses in the same setting.

Echocardiography is also important. It can detect wall motion abnormalities which can be signs of previous myocardial infarction.

Myocardial perfusion imaging (nuclear medicine myocardial perfusion studies) is another modality used for evaluation of ischaemic heart disease. It can detect regions of the myocardium which is hypoperfused during rest or activity.

Coronary angiography

Coronary angiography, usually called invasive coronary angiography or conventional coronary angiography to distinguish it from CT coronary angiography, is technique used to visualise the coronary arteries, usually in the evaluation of coronary artery disease.

If a significant stenosis of the coronary arteries is seen on the angiography, percutaneous coronary intervention can be performed in the same procedure to treat the stenosis.

Procedure

A catheter is inserted into femoral or radial artery by Seldinger technique and directed retrograde through the arterial system to the coronary arteries. The operator can use the catheter to eject contrast directly into the coronaries, which can be visualised in realtime with the use of fluoroscopy.

Aortic stenosis

Aortic stenosis (AS) refers to narrowing of the aortic valve, resulting in increased pressure load on the left ventricle. AS is mostly a disorder of the elderly (>70 years) men, and it’s the most common valvular disease. Some also have some degree of aortic regurgitation.

Diagnosis and evaluation

Echocardiography allows for assessment of the narrowing of the aortic valve opening area and the pressure gradient and velocity across the valve, which is increased in case of stenosis. It can also detect whether the aortic valve is bicuspid or tricuspid. Coronary angiography can be used to assess the degree of coronary artery disease, which is useful as pre-operative assessment if surgical treatment is considered.

A chest radiograph may show enlarged left border of the heart and dilation of the ascending aorta. ECG-gated CT of the heart is obligatory pre-operative assessment for valve replacement.