Coronary artery disease Flashcards
What is coronary heart disease? How does it occur?
It is caused by atherosclerosis. It occurs when fatty deposits called plaque build up inside the coronary arteries. Thus, this narrow down the lumen and reduces the amount of blood suppy to the heart which causes heart muscle damage which may result in infarction, arrhythmias, heart failure. Build up of plaque may start in childhood.
Plaque can crack sometimes and platelet come to the site to form blood clot, even narrow the arteries more and worsen angina and heart attack.
Types of ischemic heart disease
- Stable angina
Acute coronary syndrome (ACS) :
- Unstable angina
- Non ST segment elevation Myocardial Infarction (NSTEMI)
- ST segment elevation Myocardial Infarction (STEMI)
Risk factors Ischemic Heart Disease
Modifiable (Risk factors)
- Obesity
- Physical activity (sedentary lifestyle)
- Stress
- Cigarette smoking, tobacco use
- Lipid disorders (low HDL, high LDL, high triglycerides)
- Hypertension
- Diabetes mellitus
- Lack of estrogen in women
Non modifiable
- Age (M > 45 yrs, F>55 yrs)
- Sex (M>F)
- Family history of IHD
- Ethnicity (non white population)
Symptoms of IHD (Clinical presentation)
- Chest pain
- Shortness of breath
- Cough + hemoptysis
- Weakness, tiredness
- Reduced exertional capacity
- Dizziness
- Palpitations
- Syncope
- Leg swelling
- Weight gain
- Orthopnea (shortness of breath in supine position)
- Paroxysmal nocturnal dyspnea (shortness of breath that awake at night after 1-2 hr of sleep, felt better in upright position)
- Symptoms related to risk factors like obesity,hypertension,DM
Investigations of IHD
Electrocardiogram
- Ishcemia (ST depression, T inversion)
- Infarction (ST elevation, Q )
- Hypertrophy of ventricles / arrhythmia (Conduction)
Chest X-ray
- Cardiomegaly
- Pulmonary oedema
- Pleural effusion
Echocardiogram
- Valvular structure and function
Coronary Angiography (for CAD)
- Anatomy and patency of arteries
- Allow intervention if necessary
CARDIAC ENZYME
- Troponin I/T (cardiac muscle specific enzyme)
- enzyme assays with 100% cardiac specificity
- Raised : NSTEMI
- used to rule out unstable angina
Myocardial perfusion scanning
- Myocardium take up radioactive Thallium
- measured during and after exercise
Myocardial fractional flow reserve (FFR)
Coronary flow reserve
Stress Echocardiography
Treatment IHD
Lifestyle changes
- moderate alcohol consumption
- regular exercise
- balanced diet
- maintain healthy weight
Drugs
- antiplatelet drugs prevent thrombosis (aspirin, clopidogrel)
- beta blockers lower bp (atenolol, metoprolol)
- ACE inhibitors lower peripheral resistance and cardiac overload (blood pressure)
- Statins as lipid lowering agents
- coronary angioplasty
- coronary artery bypass graft
What is Stable angina
- Episode of chest pain caused by myocardial infarction
- Imbalance between myocardial oxygen supply and demand (during exercise)
Precipitating / Triggering factors of stable angina
- Exertion
- Extreme cold
- Heavy meals
- Stress
- Anemia
- Thyroid disease
- Bad dreams (nocturnal angina)
Clinical manifestation of stable angina
- Retrosternal discomfort (central of chest)
- Precordial chest discomfort
- Radiates to left shoulder, arms, jaw, neck
- May be associated with dyspnea, nausea, impending death
- Duration : 2 -10 mins
- Relieving factor : rest / nitrate therapy
- Breathlessness, fatigue, faintness rather than chest pain : Diabetes, elderly man
- ECG changes : Reversible ST segment depression/elevation with or without T wave inversion during chest pain is a specific finding
Treatment of Stable angina
Antiplatelet drug : low dose aspirin, clopidogrel 75 mg
Nitrates :
- Acute relief : nitroglycerine 0.4-0.6 mg sublingually (coronary vasodilatation, increase O2 supply, decrease preload & afterload)
- Long term : isosorbide nitrate 5mg 8 hrly
Beta blocker : Atenolol 100 mg/ metoprolol 200mg daily
Calcium channel blocker : Amlodipine, Verapamil, Diltiazem, Nefedipine (reduces myocardial contractility, reduce pressure)
Clinical manifestation unstable angina
- Increase frequency / intensity of episodes of angina pectoris/ chest pain
- Pain at rest
- Ischemia but no infarction (does not cause cardiac death)
- NSTEMI and unstable angina»_space;> STEMI (if obstruction coronary blood flow)
Investigations of unstable angina
ECG :
- ST depression
- T wave inversion
- no rise in cardiac isoenzyme (CK-MB) (creatine kinase)
NSTEMI (rise in cardiac enzyme)
Prinzmetal’s angina
- vasospasm
- not associated with atheroma
- ST elevation
Pathophysiology of unstable angina
- rupture of plaque in coronary artery
- thrombus
- acute reduction in coronary blood flow
- may be accompanied by coronary artery spasm
Myocardial infarction