Exam 2: Ischemic Heart Disease Spring 2024 Flashcards
Risk Factors for Ischemic Heart Disease (IHD)
2 most important risk factors for the development of atherosclerosis involving the coronary arteries are:
male gender and increasing age
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.
When does stable angina develop?
in the setting of what?
Stable angina typically develops in the setting of partial occlusion or significant (>70%) chronic narrowing of a segment of coronary artery.
What is the most common cause of impaired coronary blood flow resulting in angina pectoris?
Atherosclerosis
- but it may also occur in the absence of coronary obstruction as a result of myocardial hypertrophy, severe aortic stenosis, or aortic regurgitation
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 myocardial 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 myocardial 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 a greater degree of ST segment depression on ECG mean in terms of CAD?
The greater the ST segment depression, the greater the likelihood of significant coronary artery disease.
Specific diagnostic ECG changes for Acute MI during Exercise Stress Test:
- why is exercise stress test used for?
- is it always feasible?
Specific Changes: At least 1 mm of horizontal or downsloping ST-segment depression during or w/in 4 minutes after exercise
Uses: for detecting signs of MI and establishing the relationship to chest pain & exercise capacity
Feasible? not always feasible bc pt might not be able to exercise
Other Info from powerpoint:
Exercise ECG is less sensitive (overall sensitivity ∼75%) and specific in detecting ischemic heart disease than nuclear cardiology techniques.
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
Thesize of the perfusion abnormality is the most important indicator of the significance of the coronary artery disease detected.
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? (Modifiable)
- 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 (7-14days)
- 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
Thienopyridines (P2Y12inhibitors)
examples
- 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.