Physiology Flashcards
(15 cards)
Draw Wigger’s Diagram.
(Need to image search.)
What is the function of the LAA and the RAA?
It checks the volume of the LA. If pressure is high enough to stretch the walls of the LAA, then the LAA triggers the release of naturetic peptides. These increase secretion of sodium and water from the body and increase vasodilation to decrease blood pressure and volume. The RAA serves the same function on the right side.
What is the normal range for Stroke Volume?
60-120mL.
What is the normal range for Cardiac Output volume?
4-8mL/min.
What is the equation for CO?
CO= HRxSV.
What is Cardiac Index, what’s the normal range for it and what equation is used to calculate it?
CI is a way to factor in patient size when making calculations. CI = CO/body surface area. Normal range is 2.5-4.
What is systemic vascular resistance?
The overall resistance from the body the heart has to overcome to successfully pump blood round the body.
What is preload?
The measure of stretch/filling pressure.
What is afterload?
The amount of force the heart must overcome to eject blood.
What is considered a prolonged QT for males and females?
Males = 450ms or greater. Females = 470ms or greater.
Describe the function of the epicardial fat pads and how they may be relevant in an EP study.
They act as a shock absorber for the heart. They also provide insulation for the neurones running there, which don’t have their own insulation. This enables the neurological control of the heart. When mapping during EP studies, epicardially if the sensor is near myocardium it will be stronger, but if near a fat pad the signal from the nerves will be attenuated because of the insulating nature of the fat, so the signal will be smaller. Ablating in these areas can damage the nerves allowing for neurological control, therefore you may see CHB/HR drop/BP drop.
Why does the LAA have a higher risk of creating blot clots in AF (90% more common) compared to the RAA?
It is not actually known for definite, but theories include that the LAA has more folds and trabeculations which leads to less blood movement in the area during AF and more blood stagnation. The LAA often also undergoes chamber remodelling when in AF, whereas the RAA doesn’t, which may explain the difference.
How could AF lead to a Pulmonary Embolus?
Blood stagnation in the RAA may lead to a clot, which if dislodged and circulated would travel to the lungs.
What percentage of ischaemic strokes are caused by AF?
Approximately 20-30%.
