Cardiac Function

Atrial systole, Isovolumetric Contraction, Rapid ejection, Reduced ejection, Isovolumetric relaxation, Rapid filling, reduced filling

• Lower pressures S/D = 18/4 (18/0)
• Pulmonary artery S/D = 18/12 mean=15mmhg
• R artrium a/v = 5/4 mean=3
• RV pumps only through the pulmonary circulation
• RV valves open sooner and close later due to differences in electrical activation and pressures
• Pulmonary artery valve closure becomes longer during breathing-get splitting of the second heart sounds

• CO=HR*SV
• =HR*(EDV-ESV)
• Preload/EDV depends on HR (time for filling), muscle movment (increased venous return), blood volume and blood pressure (eg position could be a factor)

Afterload/ESV modulated by length of cardiac myocytes and inotropic state of the heart (Can be effected by HR due to changes in Ca2+ balance)

Acts directly and indirectly via determinants of SV-particularly preload and inotropic state