Ischaemic Heart Disease Flashcards
Risk factors for IHD
Male Family Hx Smoking Diabetes Hypercholesterolaemia HTN Obesity Sedentary lifestyle
Define two types of Angina Pectoris
STABLE ANGINA Atherosclerotic disease, limits heart’s ability to respond to increased demand e.g. Symptoms on exertion, relief by rest. UNSTABLE ANGINA Generally due to plaque rupture and formation of a non-occlusive thromboembolism, less commonly vasospasm (Prinzmetal angina), symptoms at rest.
Diagnosing angina…
Based on Hx STABLE - pain induced by exercise - relieved by rest and glyceryl trinitrate ECG ST-segment depression is associated with ischaemia. Angiography of coronary arteries reveals stenosis.
Managing Angina…
Lifestyle - no smoking, exercise, diet, weight loss. CABG is most effective approach. Angioplasty with stenting Balloon catheter to dilate/ destroy the stenosis and insert a cage intraluminally to prevent restenosis
Angina, Pharma management - Nitrates
NITRATES Release nitric oxide which increases cGMP and causes: - Venodilation, decease in preload and a reduction in cardiac work - Coronary vasodilation, improves coronary blood flow
Angina, Pharma management - Beta Blockers
First choice for prevention Negative inotrope can and chronotropic effects reduce cardiac work and prevent symptoms. Coronary flow only occurs during diastole, so by slowing the HR the diastolic period is longer leading to greater coronary blood flow. Anti-arrhythmic effects and reduce the risk of MI.
How does IHD manifest? Cause?
Angina MI Also important cause of chronic heart failure Associated with atherosclerosis (-> stenosis) within the coronary artery (impaired blood flow of thromboembolic occlusion). Coronary blood flow does not match demand, leading to ischaemia, which provokes the symptoms.
Angina, Pharma management - Ca channel blockers
Vasodilation and improve coronary blood flow, so preventing symptoms. Inhibit voltage gated Ca channel on vascular smooth muscle so vasodilation and decreasing BP. Verapamil work with greater effect on the heart muscle and Dihydropyrimidines on arteriolar smooth muscle VERAPAMIL (and lesser extent Diltiazem) - also have myocardial depressant and bradycardic actions, so reducing cardiac work - verapamil also exerts Class IV anti-arrhythmic activity
Angina, Pharma management - ACEIs
HOPE trial indicated ramipril reduced mortality in IHD patients
Angina, Pharma management - Potassium channel activators
NICORANDIL Combined NO donor and activator of ATP-sensitive-K- channels (target). This leads to vascular smooth cell hyperpolarisation with coronary artery vasodilation and improved coronary blood flow.
Anti platelet drugs in IHD - Aspirin
Low dose 75mg daily Favours prostacyclin production over thromboxane (platelets have no nuclei but endothelium can regenerate COX). Prostacyclin inhibits platelet activation and vasodilates. Ibuprofen may oppose beneficial actions (COX inhibitor)
Anti platelet drugs in IHD - Clopidogrel
ADP receptor antagonist - prevents platelet aggregation Equally as effective as aspirin Used in patients who cannot receive aspirin (e.g. Asthma)
Anti platelets, choosing a drug (4)
Low dose aspirin and/or clopidogrel BP controlled to
Continuous preventative drug choices IHD
1st choice, Beta blockers for more pronounced stable or unstable angina NOT for Prinzmetal angina Oral long acting nitrates might be added 2nd choice, Calcium channel blocker (If beta blocker ineffective/ contraindicated) Verapamil (or Diltiazem) would be used OR Long acting DHP Ca channel blocker particularly effective at reversing vasospasm (first choice for Prinzmetal angina) REFRACTORY DISEASE (not yielding to treatment) Beta- blockers PLUS DHP (but not with verapamil, risk bradycardia) Nicorandil may be added
Addition for Unstable Angina
Low molecular weight heparin
IHD Treaement Pathway
