Ventricular Function II Flashcards
What is Stroke work?
Stoke Work is the work done by a ventricle to eject a volume of blood
Can be estimated by SV x MAP (left) or MPP (right)
What is cardiac work?
Stroke Work x Heart Rate
What is the pressure-volume area?
Represents the total mechanical energy generated by a single heart beat
Can be divided into external work and elastic potential energy
There is a high correlation between PVA and energy demands of the heart
How is the mechanical efficiency of the heart defined?
The ratio of useful energy produced (stroke work) to myocardial oxygen consumption
What is the Fick Principle?
The amount of substance that enters an organ minus the amount that leaves the organ in an interval of time, is equal to the amount consumed by that organ
Xtc = Q([X]a - [X]v)
What three measurements are required to determine cardiac output using the Fick Method?
O2 consumption by the whole body
O2 concentration of pulmonary venous blood
O2 concentration of arterial blood
What is the thermodilution method for determining cardiac output?
Swan-Ganz catheter is inserted through a systemic vein and fed through the right heart, with the tip in the pulmonary artery
Cold saline is injected into the right atrium, and a sensor is used to calculate the right ventricular CO from the change in blood temp and the volume and temp of the saline solution that was injected
What imaging techniques can be used for measuring cardiac output?
Radiolabeling techniques to estimate ESV and EDV
Echocardiography to estimate changes in ventricular volume
What is the cardiac index?
Cardiac output per square meter of body surface
What is the difference between an acute and gradual rise in pericardial pressure?
Acute rise - will cause cardiac tamponade and result in hypotension and reflex tachycardia
Gradual - pericardium will gradually stretch and shift the volume-pressure curve to the right, allowing the pericardium to accommodate larger volumes
