Definition : Stable Angina pectoris is defined as the chest pain which occurs due to Ischaemia (and hence lack of oxygen) of Heart muscle due to fixed atheromatous stenosis of one or more coronary arteris.
Angina pectoris is a symptom(of diseases like Ischaemic heart disease,aortic valve disease,hypertrophic cardiomyopathy) rather than a disease.It can occur anytime whenever there is an imbalance between oxygen supply and demand.
Clinical features :
Characterised by central chest pain,discomfort or breathlessness.
Some patienst experience the pain when start walking and that later it does not return despite of greater effort - Startup Angina.
Physical examination includes through search for -
evidence of vlave disease (particularlyof aortic valve)
Important risk factors (like hypertension,diabetes)
left ventricular dysfunction (ex-cardiomegaly,gallop rhythm)
Other manifestations of arterial disease (like carotid bruits,peripheral vascular disease) and unrelatd conditions that may exacerbate angina (anemia,thyrotoxicosis).
Investigations :
Resting ECG : May show evidence of previous heart disease but is often normal.Ocassionally,there is T wave flattening or inversion in some (nonspecific evidence of myocardial Ischemia or damage).
The most convincing ECG fiding is reversible ST segment depression or elvation (with ir without T-wave inversion).
Exercise ECG : This Exercise Tolerance Test (ETT) is usually performed by a standart treadmill or bicycle ergometer protocol while monitoring the patient's ECG,blood pressure and general condition.Plantar or down sloping ECG depression of 1mm or more is indicative of Ischaemia.
Up-sloping occurs in normal individuals.
Exercise testing is not infalliable and may cause false positive results in presence of digoxin therapy, left ventricular hypertrophy, left bundle branch block or Wolf Parkinson White syndrome.
The predictive value of exercise testing is lower in women than in men.
Other forms of stress testing :
Myocardial perfusion scanning -
This test is helpful in patients with unequivocal or uninterpretable exercise tolerance test and those who are unable to exercise.
Its predictive valus is higher than that of exercise ECG.
This technique involves obtaining scintiscans of myocardium at rest and during stress , after administration of radioactive thallium.It may be used with conventional stress testing or some form of pharmacological stress such as controled infusion of dobutamine.
A perfusion defect present during stress but not rest provides evidence of reversible myocardial ischaemia.whereas a persistent perfusion defect seen during both phases is indicative of previous myocardial infarction.
Stress Echocardiography -
This is an alternative to myocardial ishaemic scanning.the technique uses transthoracic echocardiography to identify ischaemic segments of myocardium and areas of infarction.
Coronory arteriography -
This provides detailed information about extent and nature of coronory artery disease and is usually performed with a view to coronary bypass grafting or percutaneous coronary intervention.It is done under local anaesthesia and is indicated when non-invasive tests have failed to elucidate the cause of the chest pain.
Precipitating factors :
Antiplatelet drug treatment -
Angina pectoris is a symptom(of diseases like Ischaemic heart disease,aortic valve disease,hypertrophic cardiomyopathy) rather than a disease.It can occur anytime whenever there is an imbalance between oxygen supply and demand.
Clinical features :
Characterised by central chest pain,discomfort or breathlessness.
Some patienst experience the pain when start walking and that later it does not return despite of greater effort - Startup Angina.
Physical examination includes through search for -
evidence of vlave disease (particularlyof aortic valve)
Important risk factors (like hypertension,diabetes)
left ventricular dysfunction (ex-cardiomegaly,gallop rhythm)
Other manifestations of arterial disease (like carotid bruits,peripheral vascular disease) and unrelatd conditions that may exacerbate angina (anemia,thyrotoxicosis).
Investigations :
Resting ECG : May show evidence of previous heart disease but is often normal.Ocassionally,there is T wave flattening or inversion in some (nonspecific evidence of myocardial Ischemia or damage).
The most convincing ECG fiding is reversible ST segment depression or elvation (with ir without T-wave inversion).
Exercise ECG : This Exercise Tolerance Test (ETT) is usually performed by a standart treadmill or bicycle ergometer protocol while monitoring the patient's ECG,blood pressure and general condition.Plantar or down sloping ECG depression of 1mm or more is indicative of Ischaemia.
Up-sloping occurs in normal individuals.
Exercise testing is not infalliable and may cause false positive results in presence of digoxin therapy, left ventricular hypertrophy, left bundle branch block or Wolf Parkinson White syndrome.
The predictive value of exercise testing is lower in women than in men.
Other forms of stress testing :
Myocardial perfusion scanning -
This test is helpful in patients with unequivocal or uninterpretable exercise tolerance test and those who are unable to exercise.
Its predictive valus is higher than that of exercise ECG.
This technique involves obtaining scintiscans of myocardium at rest and during stress , after administration of radioactive thallium.It may be used with conventional stress testing or some form of pharmacological stress such as controled infusion of dobutamine.
A perfusion defect present during stress but not rest provides evidence of reversible myocardial ischaemia.whereas a persistent perfusion defect seen during both phases is indicative of previous myocardial infarction.
Stress Echocardiography -
This is an alternative to myocardial ishaemic scanning.the technique uses transthoracic echocardiography to identify ischaemic segments of myocardium and areas of infarction.
Coronory arteriography -
This provides detailed information about extent and nature of coronory artery disease and is usually performed with a view to coronary bypass grafting or percutaneous coronary intervention.It is done under local anaesthesia and is indicated when non-invasive tests have failed to elucidate the cause of the chest pain.
Precipitating factors :
- Physical exertion
- Heavy meals
- Cold exposure
- Heavy meals
- Intense emotion
- Lyng flat (decubitus angina)
- Vivid dreams (nocturnal angina)
Antiplatelet drug treatment -
- Low dose aspirin - 75 - 150 mg - reduces the risk of myocardial infarction.
- Clopidogrel 75 mg - more expensive and given to avoid side effects of aspirin (like dyspepsia)
Antianginal drug treatment -
- Nitrates - Act directly on vascular smooth muscle and produse venous and arteroilar dilatation.They reduse the myocardial oxygen demand (by reducing preload and after load) and increase myocardial oxygen supply (by vasodilatation)
- Beta blockers - They reduce myocardial oxygen demand by reducing heart rate, blood pressure and myocardial contractility.But they exacerbrate the symptoms of peripheral vascular disease and may provoke bronchospasm in patients with obstructive airway disease.
- Calcium antagonists - These dugs inhibit the slow inward current caused by the entry of extracellular calcium through the cell membrane of excitable smooth muscle and lower myocardial oxygen demand by reducing blood pressure and myocardial oxygen contractility.
- Potassium channel activators (Nicorandil , Diazoxide) - These drugs have arterial and venous dilating properties but do not exhibit the tolerance seen with nitrates.
Invasive methods :
- Percutaneous coronary intervention (PCI) -A think guide wire is passed into the stenosis coronary artery under radiographic control.This wire is used to position a balloon whic is then inflated to dilate the stenosis.
- Coronary artery bipass graftingThe Internal mammary arteris or the reversed segments of patient's own saphenous vien.
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