February 2, 2016 - Cardiac Drugs

Question 1

Principles of Managing an MI

Answer 1

The very basic principles it comes down to are increasing oxygen supply and decreasing oxygen demand.

An MI occurs because the demand for oxygen is greater than the supply.

Question 2

Law of Laplace

Answer 2

Tension = (Pressure x Radius) / (Wall Thickness)

By decreasing the pressure and preload in the heart, we can decrease the tension and decrease the amount of work the heart has to do.

Question 3

Mechanisms of Nitroglycerine

Answer 3

1. Arterial dilation
2. Coronary dilation
3. Venous dilation (lower tension and less work)
4. Venous dilation (lower ventricular diastolic pressure)

Question 4

Coronary Perfusion Pressure

Answer 4

CPP = Pressure _aorta - Pressure _myocardium

CPP = Diastolic Aortic Pressure - LVEDP

Perfusion of the coronary arteries occurs during diastole.

Question 5

ß-Blockers and Myocardial Ischemia

Answer 5

1. Slower heart rate = fewer heartbeats = decreased O₂ demand
2. Slower heart rate = longer diastolic time = increased O₂ supply
3. Lower contractility = lower pressure = lower tension = decreased O₂ demand

Question 6

Spironolactone

Answer 6

Is a K-sparing diuretic.

Blocks the uptake of sodium in the kidneys, causing water to flow out.

Improves survival.