6. Ischemic Heart Disease Flashcards
what is the leading cause of death in industrialised nations?
atheroesclerosis
what is the most common manifestation of ischemic heart disease?
Angina pectoris
What does angina pectoris mean?
Strangling of the chest
what does angina mean?
uncomfortable sensation in the chest and neighbouring structures due to an imbalance between oxygen supply and demand.
Define ischemic Heart Disease
imbalance between myocardial oxygen supply and demand. Results in myocardial hypoxia and accumulation of waste metabolites most commonly caused by CAD.
Define stable angina
Chronic pattern of stable angina pectoris precipitated by physical activity or emotional upset, relieved by rest within a few minutes. Permanent myocardial damage does not result.
Define variant angina
anginal discomfort usually at REST. develops because of artery spasm rather than increase of oxygen demand. Also termed Prinzmetal angina.
Define silent ischemia
Asymptomatic episodes of myocardial ischemia. can be detected by EKG or other lab studies
Define unstable angina
Pattern of increased frequency and duration of angina episodes produced by less exertion or at rest; high frequency of myocardial infarction if untreated.
Myocardial Infarction
Region of myocardial necrosis caused by prolonged cessation of blood supply.
What are the Determinants of Myocardial oxygen Supply?
- oxygen content of the blood
- coronary blood flow
- Coronary perfusion pressure
- Coronary vascular resistance
- external compression
- Instrinsic regulation
- local metabolites
- endothelial factors
- neural inervation
What determines oxygen content?
- hemoglobin concentration
2. degree of systemic oxygenation
Coronary blood flow formula
Q: coronary blood flow
P: vessel perfusion pressure
R: coronary vascular resistance
Q= directly proportional to P/R
The predominance of coronary perfusion takes place during:
Diastole
How can you approximate the coronaries perfusion pressure?
by the aortic diastolic pressure
what type of conditions can decrease coronary artery perfusion pressure?
Conditions that decrease aortic diastolic pressure e.g. hypotension or aortic valve regurgitation.
What modulates coronary vascular resistance?
- forces that externally compress the coronary arteries
2. factors that alter intrinsic coronary tone
What region is the most vulnerable to ischemic damage?
subendocardium, adjacent to the high intraventricular pressure.
how does external compression define coronary vascular resistance?
Compression during sistole augments the CVR especially in the subendocardium.
Can the heart increase oxygen extraction on demand?
NO, it can only augment the blood flow because on its basal state it already removes as much oxygen as posible.
What factors participate in the regulation of coronary vascular resistance?
- external compression
2. Factors that alter intrinsic coronary tone
What is the prime metabolic mediator of the vascular tone?
Adenosine
What are the factors that alter intrinsic coronary tone?
- metabolic factors
- endothelial factors
- neural innervation
What is inhibited in states of of hypoxemia?
- aerobic metabolism
2. oxidative phosphorilation in mitochondria