Ischemic Heart Disease Flashcards
Has only a single blood supply
Posterior papillary muscle
Accounts for the majority of fluctuation in coronary O2 supply
Coronary Blood Flow
The diastolic pressure as the coronaries fill during diastole
Perfusion Pressure
The coronary arteries fill during
Diastole
Epicardial coronary vessels can be compressed in a condition where the coronary dives into the muscle. This is called
Myocardial bridging
The subendocardium is subject to LV wall pressure, which makes the subendocardiu more susceptible to
Ischemia
What are the 3 factors affecting intrinsic coronary tone?
Local metabolites, Endothelial Factors, and Neural innervation
Primarily adenosine, as well as lactate, hydrogen ions, and CO2
Local metabolites
What are the two endothelial factors
Vasodilator and vasoconstrictors
Hypoxemia inhibits aerobic metabolism and oxidative phosphorylation in mitochondria. This results in increased coronary flow via the vasodilator
Adenosine
Produced in response to Ach, histamine, and. Serotonin. Then converts GTP to cGMP and causes smooth muscle relaxation
Nitric Oxide
Released in response to hypoxia, shear stress, Ach and platelet factors
-functions through cAMP related mechanism
Prostacyclin
Released in response to Ach and pulsation blood flow
Endothelial derived hyperpolarizing factor (EDHF)
Vasoconstrictor released by thrombin, epinephrine, and angiotensin II
Endothelial-1
In atherosclerotic vessels, release of vasodilator may decrease, causing endothelial dysfunction by a shift in favor of
Vasoconstrictors
What are the three things that dictate myocardial oxygen demand?
Wall stress, HR, and contractility
Increased LVEDP, hypertension, and aortic stenosis, all increase
Wall stress
How do we find wall stress?
Wall stress = pressure/2 x radius/wall thickness
What has a bigger effect on increasing wall stress, increasing pressure? Or radius?
Increasing pressure
Decrease oxygen demand
Beta-blockers
With regards to neurostimulation of intrinsic coronary tone, which effects are greater, sympathetic or parasympathetic?
Sympathetic effects
NOT a component of myocardial oxygen demand
O2 content
Resistance is:
- ) Directly proportional to?
- ) Inversely proportional to?
- ) Length
2. ) r^4
So as the vessel narrows, the resistance is drastically increase by change in
Radius
Epicardial arteries are more susceptible to
Plaque
The smaller arterioles are free from plaque and have the ability to adjust their vasomotor tone to allow greater
blood flow as needed. This is called?
Compensatory Vasodilation