Unit 2 Day 1 (Tuesday 4/7) Flashcards
Coronary Atherosclerosis Risk Factors
-risk factors: smoking, hypertension, dyslipidemia, diabetes, obesity, inflammation, stress, sedentary lifestyle, male gender, age, high LDL, low HDL
Autoregulation
- an adaptive mechanism to maintain perfusion in face of altered perfusion pressure
- an epicardial coronary stenosis may cause autoregulation to be exhausted and lead to ischemia
Treatment for Stable Coronary Heart Disease: Inc O2 Supply
- perfusion pressure: prevent hypotension
- diastolic time: rate-slowing drugs (e.g. beta blockers)
- coronary resistance: vasodilator drugs (e.g., nitrates, calcium channel blockers); coronary angioplasty or bypass surgery
- oxygen content: treat anemia and hypoxemia
Treatment of Unstable Coronary Disease: Reducing O2 Demand
- systolic pressure: Antihypertensive drugs
- heart rate: Rate-slowing drugs (beta blockers, calcium channel blockers)
- wall tension: Limit LV cavity size by limiting excessive preload (diuretics, nitrates)
- inotropic state: negative inotropes (beta blockers and Ca channel blockers)
- revascularization: coronary angioplasty, coronary artery bypass surgery
Pathophys of Unstable Coronary Artery Disease
- Inflammation in arterial wall
- Weakening of fibromuscular cap
- Abrupt plaque fissure or rupture
- Thrombogenic components (lipids, tissue factor) exposed to blood
- Thrombosis with partial or complete vessel occlusion
- Myocardial injury and/or necrosis (serum markers)
- Cardiac dysfunction, risk of arrhythmias, death
Dx of CAD with ECG
• Resting ECG:
– ST segment changes (usually depression) – T wave inversion
– Q-waves (indicate prior infarction)
• Exercise ECG (stress testing): – dynamic ST segment changes
Angiography
- diagnostic tool
- underestimates pathologic extent of CAD
- underestimates severity of CAD
Angioplasty
- reduces risk of recurrent ischemic events in unstable angina
- balloon dilation to expand vessel wall
- sometimes vessel restenoses
Tx for MI with ST Elevation
- Immediate aspirin, nitroglycerin, ± beta blocker
* Reperfusion therapy ASAP: Usually coronary angioplasty, if unavailable thrombolytic therapy
Coronary Bypass Grafting
-using other arteries to reperfuse heart
– Internal mammary artery
– Saphenous vein
– Prosthetic materials have not proven successful as coronary grafts