Ischemic Heart Disease (Exam IV) Flashcards
Risk Factors for Ischemic Heart Disease (IHD)
What percentage of patients will have a risk factor for ischemic heart disease?
30%
What are the manifestations of IHD?
- Angina Pectoris
- Acute MI
- Sudden Death
- Dysrhythmias
What is Angina Pectoris
Chest pain d/t imbalance between coronary blood flow and myocardial oxygen consumption.
Stable angina typically develops in the setting of partial occlusion or significant (>______%) chronic narrowing of a segment of the coronary artery.
- > 70%
Angina pectoris reflects the intracardiac release of what two substances during ischemia?
- Adenosine
- Bradykinin
What are the CV effects of adenosine and bradykinin release?
- Stimulate Cardiac nociceptors whose afferent neurons converge with the T1 to T5 sympathetic ganglia resulting in chest pain.
- Slow AV conduction
- Decrease Contractility
How would a patient describe angina pectoris?
- Retrosternal chest discomfort
- Elephant sitting on their chest
- Chest discomfort radiates to left shoulder/jaw
- SOB and dyspnea
Angina Pectoris affect which dermatomes?
- C8 to T4
What factors can induce angina pectoralis?
- Physical exertion
- Emotional tension
- Cold weather
Differentiate Chronic vs Unstable Angina
Chronic stable: Chest pain that does NOT change in frequency or severity in a 2-month period
Unstable: Chest pain increasing in frequency and/or severity without an increase in cardiac biomarkers
During subendocaridal ischemia, the standard 12-lead ECG demonstrates ST-segment _______ that coincides with the anginal chest pain. This may be accompanied by transient symmetric _________ inversion.
During subendocardial ischemia, the standard 12-lead ECG demonstrates ST-segment depression that coincides with the anginal chest pain. This may be accompanied by transient symmetric T-wave inversion.
What does the Exercise Stress Test evaluate on the EKG?
- Degree of ST-segment depression
The greater the degree of ST-segment depression, the greater the likelihood of significant coronary artery disease.
What does nuclear stress imaging assess?
- Assesses coronary perfusion (greater sensitivity than other tests)
- Tracer activity in perfused vs ischemic areas
- Estimates LV systolic size and function
- Differentiates new perfusion abnormality vs. “old” MI
The size of perfusion abnormality will correlate with the significance of CAD.
What drugs can be administered to produce a rapid HR to create cardiac stress?
- Atropine
- Dobutamine
What is the chemical tracer used to analyze cardiac blood flow?
- Thallium
These drugs dilate normal coronary arteries but evoke no change in the diameter of atherosclerotic coronary arteries.
- Adenosine
- Dipyridamole
What does an ECHO assess in IHD patients?
- Wall motion abnormalities
- Valvular functions
Purpose of coronary angiography.
- Determines the location of occlusive disease
- Diagnose Prinzmetal (variant/spasm) angina
- Assess results of angioplasty/stenting
Coronary angiography does NOT measure what?
- Stability of the plaque.
- Does not tell you when the plaque will rupture.
Treatment for angina pectoralis?
- Cessation of smoking
- Ideal body weight
- Low-fat, low-cholesterol diet (Statins)
- Regular aerobic exercise
- Treatment of hypertension
Patients are placed on statins when LDL levels are above ________ mg/dL.
160 mg/dL
Providers would like a 50% reduction in LDL during statin therapy.
Drug therapy for angina pectoralis
- Antiplatelet drugs
- Nitrates
- β-blockers
- Ranolazine
- CCB
- ACE inhibitors
Aspirin inhibits the enzyme _________. This results in the inhibition of ________, which plays an important role in platelet aggregation.
Aspirin inhibits the enzyme COX-1. This results in the inhibition of thromboxane A2, which stimulates activations for new platelets and is a potent vasoconstrictor.
Are the effects of aspirin reversible?
What is the dose for aspirin?
- No, COX-1 inhibition will last for the duration of platelet lifespan (7 days)
- 75-325 mg/day
How do platelet glycoprotein IIb/IIIa receptor antagonists work?
What are examples of these antiplatelet drugs?
- Inhibit platelet aggregation
- Abciximab, Eptifibatide, Tirofiban
Name a Thienopyridines (P2Y12inhibitors) drug.
- Clopidogrel (Plavix)
- Prasugrel
Is Clopidogrel reversible?
No, Clopidogrel is irreversible.
MOA of Clopidogrel
- Blocks ADP from binding to P2Y12 receptor, which will inhibit platelet aggregation.
7 days after cessation of clopidogrel, ____% of platelets will have recovered normal aggregation function.
- 80%
Clopidogrel is a _______ that is metabolized into an active compound in the liver.
- Prodrug
________ % of patients taking clopidogrel demonstrate resistance or hyperresponsiveness.
- 10-20%
_________ can affect the enzyme that metabolizes clopidogrel to its active compound and thereby can reduce the effectiveness of clopidogrel.
- PPI
What drug has a similar mechanism action as clopidogrel, more predictable pharmacokinetics, and a higher risk of bleeding?
- Prasugrel
How does Nitrate treat myocardial ischemia?
- Decrease the frequency, duration, and severity of angina pectoris.
- Dilate Coronary Arteries and Collaterals
- Decrease peripheral vascular resistance
- Decrease Preload
- Anti-thrombotic effects
Nitrates will increase the amount of exercise required to produce ST-segment depression.