Cardiac cycle Flashcards
What is the cardiac cycle?
Mechanical and electrical events that repeat with every heartbeat
4 main stages of cardiac cycle
Inflow phase (diastole), isovolumetric contraction (systole), outflow phase (systole), isovolumetric relaxation
What are End Diastolic Volume and End diastolic pressures?
Left-120ml and 8-12mmHg. Right- 3-6mmHg
Phase 4 of cardiac cycle.
Ejection out of ventricles, maximal flow reached early, left atrial pressure initially decrease due to it being pulled down, blood continues to flow into atria and pressures rise, aortic and pulmonary valves shut when intraventricular pressure falls sufficiently (S2)
Dicrotic notch
Back flow into ventricles on aortic and pulmonary artery valve closure
End systolic volume in ventricles
50ml
Phase 6 of cardiac cycle
Ventricle pressure below atria so AV valves open, ventricular pressure continues to fall due to relaxation but then increases, fall in atrial pressure on AV valve opening, S3- ventricular filling, 90% of blood filed passively, atrial kick - additional contribution of atria, aortic and pulmonary artery pressures continue to fall
Where is there asynchrony in the heart?
right atrial depolarises before left, left ventricle depolarises before right, right ventricular ejection before left
Heart rate in new born
70-190
Heart rate in infant
80-120
Heart rate in children
70-130
Heart rate in adult
60-100
Heart rate in well trained athletes
40-60
What can reduce atrial kick?
Atrial fibrillation
What do a, c and v waves represent of atrial pressure diagram?
a- contraction of atrium, c- pressure due to bulging, v-filling pressure
