Angina Flashcards
What is angina pectoris (CAD)?
Acute chest pain due to insufficient oxygen to myocardium
What is the most common cause of CAD?
Atherosclerosis
What is the major problem with CAD?
Narrowing or occlusion of coronary artery, which causes Myocardial ischemia
Ischemia
Not enough Oxygen delivered to tissue
What is a major sign/symptom of Angina Pectoris?
Pain radiating to left shoulder, left arm, spine, neck and jaw
What are the 4 types of Angina Pectoris?
- Stable angina
- Variant (unstable) angina
- Vasospastic angina
- Silent angina
Stable angina
Fairly predictable, intensity& duration. Pain usually relieved by rest; pain caused by increased O2 demand, blood supply limiting
Variant (unstable) angina
Occurs unexpectedly, even at rest; due to transient platelet aggregation or coronary thrombosis, often precursor to MI; decreased O2 supply-unchanged demand
Vasospastic angina
↓ myocardial blood flow caused by spasms of coronary arteries
Silent angina
Occurs in absence of angina pain
What are the primary determinants of myocardial O2 supply?
A. Coronary blood flow
B. O2 content of the blood
C. O2 extraction by the myocardium
What are the primary determinants of myocardial O2 requirement (demand)
A. Wall stress [Ventricular systolic pressure (afterload), ventricular radius (volume or preload) and wall thickness]
B. Heart rate
C. Myocardial contractility
What are the goals of pharmacotherapy of angina pectoris?
Decrease O2 demand, increase blood supply
Decrease O2 demand, increase blood supply treatment needs:
- Slow the heart rate
- Reduce contractility
- Dilate veins so heart receives less blood (decrease preload)
- Lower BP (will decrease afterload/ work of heart)
- Increase coronary blood flow and oxygen supply (use nitroglycerin)
What are the 3 major classes of drugs used to tx angina?
- Organic nitrates
- Ca2+ channel blockers
- Beta-adrenergic antagonists
Organic nitrates
Used most commonly for CAD. Members of this class include prototype - Nitroglycerin
Nitrate MOA
- Act by increasing nictric oxide (NO) production
- NO activates guanylate cyclase to increase formation of cyclic GMP
- This results in dephosphorylation of myosin light chain (Myosin is a protein involved in relaxation of smooth muscle)
Actions of Nitrate
- Dilate veins more than arteries
2. Dilate some small arteries/atrioles
Pharmacologic effect of Nitrate
Rapid onset, short time to reach maximal effect for sublingual or spray forms (NTG)
Adverse effects of Nitrats
Postural hypotension, dizziness, blurred vision, xerostomia and headache
Pharmacokinetics of Nitrate
- Hepatic first-pass metabolism is high and oral bioavailability is low for nitroglycerin and isosorbide dinitrate.
- Isosorbide mononitrate (long-acting) is not subject to first-pass metabolism and is 100% available after oral administration
What inhibitor should you not use with Nitroglycerin?
PDE5 inhibitor (if taken 24 hours prior to appt)
What are some dental implications of an acute angina attack?
- Prepare to treat an acute angina attack in patient with history of angina
- Ensure that patient has personal supply of sublingual or spray form of NTG
- Appreciate that long-acting nitrates or nitrate formulations are not useful for treating an acute attack
- Confirm that patient has not used a PDE5 inhibitor in last 24 hr
- Ensure that patient is seated before taking NTG
