Mech of the Heart (2) 3 Flashcards
What is diastole?
Ventricular relaxation during which they fill with blood?
What is systole?
Ventricular contraction during which blood is ejected into the arteries
What is End-diastolic volume?
The volume in the ventricles just before contraction starts
What is end-systolic volume?
The volume in the ventricles after contraction has occurred and as much blood has been expelled as is going to
What is stroke volume (SV)?
SV = EDV - ESV
What is the ejection Fraction?
The proportion of the end-diastolic volume that is pumped out of the heart. EF = SV/EDV
What is the normal EF and during exercise?
Normal people = 65%
During exercise = maybe 80%
What are the 7 phases of the cardiac cycle?
1) Atrial systole
2) isovolumic contraction
3) rapid ejection
4) reduced ejection
5) Isovolumic relaxation
6) rapid ventricular filling
7) reduced ventricular filling
What is atrial systole seen as on the ECG?
The P wave
What sound may be heard during atrial systole?
Abnormal S4. It is valve incompetency due to PE, heart failure or tricuspid incompetency
What is the jugular pulse?
Small pulse on the jugular during atrial systole as some blood is pushed back into the jugular vein.
What is isovolumic contraction seen as on the ECG?
QRS complex
What sound is heard during isovolumic contraction?
S1, caused by the AV valves closing (lub)
What is seen on the ECG during rapid ejection?
Nothing as there is no electrical activity
What is seen on the ECG during reduced ejection?
T wave as the cardiac cells begin to repolarise.
T wave = ventricular repolarisation
What can be seen on the pressure graph during isovolumic relaxation?
The v wave as the atrial blood pushes the tricuspid valve.
Dichrotic notch which is a small, sharp increase in atrial pressure due to the rebound pressure against the aortic valve as the distended aortic wall relaxes
What is heard during isovolumic relaxation?
S2 when the aortic and pulmonary valves close (dub)
What can be heard during rapid ventricular filling?
S3 which is abnormal and due to turbulent ventricular filling. May be due to severe hypertension or mitral valve incompetence
What is reduced ventricular filling (slow) also known as ?
Diastasis
What should systemic blood pressure be?
120/80mmHg
What should pulmonary blood Pressure be?
25/5mmHg
What happens when the pulmonary valve closes?
The diastolic pressure in the pulmonary artery increases
What is Pulmonary Artery Wedge Pressure (PAWP)?
Measuring the preload on the left side of the heart by inserting a balloon into the pulmonary artery and inflating it so no blood can pass
What is plotted on a pressure-volume loop?
Ventricular pressure (Y) against ventricular volume (X)
What is point 1 on a pressure-volume loop?
End-diastolic volume
What is point 2 on a pressure-volume loop?
Isovolumic contraction
What is point 3 on a pressure-volume loop?
End systolic Volume (ESV)
What point represents preload on a pressure-volume loop?
Point 1
What point gives an idea of afterload on a pressure-volume loop?
Just after point 2
What is cardiac contractability?
Contractile capability (strength if contraction) of the heart. Simple measure is ejection fraction
