5.5 - Medical Management of IHD

medical management of angina pectoris

1. treat associated disease → HTN, diabetes, hypercholesterolemia

   • each increases mismatch between myocardial supply and demand and/or accelerates coronary disease

2. modify risk factors

   • address smoking, alcohol exposure, stress, lifestyle, other modifiable cardiovascular events

3. use medications

4. revascularize when necessary

pharmacologic therapy

• nitrates — vasodilators, predominantly venodilators

  • decreases cardiac load and decreases oxygen demand

  • taken prophylactically to address acute pain

  • reduces symptoms, but does not cure or change progression of disease

• beta-blockers — decrease heart rate and contractility, resulting in decreased myocardial oxygen demand

  • non-selective beta-blockers may cause unwanted effects

• calcium channel blockers — decrease intracellular calcium

  • results in vasodilation of coronary, peripheral, and pulmonary vasculature

  • reduces myocardial workload and oxygen requirement

• statins — enhanced hepatic LDL receptors to capture cholesterol from blood

  • increases HDL, decreases circulating LDL

  • anti-inflammatory effects

• ACE inhibitors — antihypertensive effects to reduce cardiac afterload

• antiplatelet therapy — diminish platelet adherence and thereby thrombosis

  • aspirin, clopidogrel

  • reduces platelet aggregation to decrease thrombosis

revascularization

reopening of occluded vessels using:

• percutaneous transluminal coronary angioplasty / balloon angioplasty — balloon catheter over a guide wire threaded through occluded artery

  • balloon is inflated and flattens atherosclerotic plaque and thrombus against arterial wall

  • arterial lumen is enlarged and blood flow immediately restored

  • stenosis of vessels recur within 6 months in 10-50% patients

• stents — expandable mesh left in place followoing balloon removal to keep plaque from recurring

  • decreases re-stenosis to 20-30%

  • bare metal → re-stenosis more likely

  • drug-eluting → re-stenosis less likely

    • increased risk of thrombosis for first year in place

    • require long-term use of aspirin or clopidogrel

• non-balloon angioplasty — rotational and laser atherectomy, excision of atherosclerotic plaque

• coronary artery bypass grafting (CABG) — segment of healthy artery or vein harvested from donor site of body and grafted to site of occluded coronary artery

  • blood flow bypasses area of occlusion

  • common graft donor sites:

    • saphenous vein of leg → re-occlusion within 10 years in 30% of cases

    • internal mammary artery of chest → more resistant to re-occlusion; preferable procedure

  • perioperative mortality rate is 1%

immediate medical management of MI

1. supplemental oxygen by nasal cannula

2. sublingual nitroglycerin 0.4 mg every 5 min for three doses

3. aspirin 160 mg or 325 mg chewed and swallowed

   • limit platelet aggregation and subsequent thrombus formation

4. morphine 1-6 mg IV for pain management and anxiety reduction

goals after MI

goals to minimize infarct size and prevent lethal arrhythmia, with treatment depending on extent of infarction and ECG findings

• ST segment not elevated → partial blockage of coronary blood flow

  • no benefit from fibrinolytic therapy

• ST segment elevated → complete blockage of coronary blood flow

  • more profound ischemia

  • benefits from fibrinolytic therapy (t-PA, steptokinase)

• other medications for longer-term management → beta blockers, CCBs, ACEIs, lipid-lowering drugs, antiarrhythmic drugs

• pacemaker