What is coronary blood flow directly related to?
Coronary perfusion pressure
Coronary blood flow is influenced by coronary perfusion pressure and inversely related to coronary vascular resistance and heart rate.
What is coronary blood flow inversely related to?
Coronary vascular resistance and heart rate
Heart rate affects the time available for perfusion in diastole.
How is coronary perfusion pressure estimated?
Difference between systemic diastolic pressure and left ventricular diastolic pressure
This estimation helps in understanding coronary blood flow dynamics.
For what range of systolic blood pressures is coronary blood flow autoregulated in normal hearts?
50 to 150 mm Hg
Autoregulation ensures adequate blood flow despite fluctuations in systemic blood pressure.
In patients with CAD, which area of the heart is most at risk for ischemia?
Subendocardium of the left ventricle (LV)
This area is particularly vulnerable due to its position and perfusion characteristics.
When is the right ventricle (RV) perfused during the cardiac cycle?
During the entire cardiac cycle
The RV has low intracavitary pressure, allowing for continuous perfusion.
What factors improve myocardial oxygen supply?
Low left ventricular diastolic pressure, normal systemic diastolic pressure, and low heart rate
These factors enhance coronary blood flow and oxygen delivery to the myocardium.
What is the most reliable ECG sign of myocardial ischemia?
Flat or downsloping ST segment depression ≥0.1 mV
Which method detects myocardial ischemia earlier and more frequently than the ECG?
Transesophageal echocardiography (TEE)
In what context is transesophageal echocardiography commonly used?
Cardiac surgery
What does a pulmonary artery catheter reveal in the context of myocardial ischemia?
Acute increases in left atrial pressures associated with ischemia-induced stiffening of the LV
True or False: The pulmonary artery catheter is a sensitive and specific monitor for myocardial ischemia.
False
What factors influence left atrial pressure during surgery, affecting the pulmonary artery catheter’s effectiveness?
Many other things
