Cardiac Output and Heart Sound PDF

Cardiac output and heart sound Sovan Bagchi, Professor www.gmu.ac.ae COLLEGE OF HEALTH SCIENCES  Learning Objectives Define cardiac output Describe cardiac indices and state their normal values Describe...

Cardiac output and heart sound Sovan Bagchi, Professor www.gmu.ac.ae COLLEGE OF HEALTH SCIENCES  Learning Objectives Define cardiac output Describe cardiac indices and state their normal values Describe afterload and preload State the Frank Starling Principle Describe the effect of Frank – Starling mechanism on end diastolic volume and stroke volume  Cardiac Output Cardiac Output is the volume of blood pumped each minute, and is expressed by the following equation: CO = SV x HR Where: CO is cardiac output expressed in L/min (normal ~5 L/min) SV is stroke volume per beat HR is the number of beats per minute Ejection fraction is most commonly measured using echocardiography. This non-invasive technique provides good estimates of end-diastolic (EDV) and end-systolic volumes (ESV), and stroke volume (SV = EDV- ESV). Normally, EF is >60%. For example, if the SV is 75 ml and the EDV is 120 ml, then the EF is 63%.  Cardiac indices or volumes SV = end diastolic volume (EDV) - end systolic volume (ESV) EDV = amount of blood collected in a ventricle during diastole ESV = amount of blood remaining in a ventricle after contraction  Stroke Volume (SV) SV = EDV - ESV Is determined by three factors: preload, afterload, and contractility. Preload gives the volume of blood that the ventricle has available to pump Contractility is the force that the muscle can create at the given length Afterload is the arterial pressure against which the muscle will contract. These factors establish the volume of blood pumped with each heart beat. Preload Afterload  Cardiac Reserve Cardiac reserve is the difference between resting and maximal CO Cardiac Output: Example CO (ml/min) = HR (75 beats/min) x SV (70 ml/beat) CO = 5250 ml/min (5.25 L/min)  Learning Resources Text Book: Guyton and Hall Textbook of Medical Physiology, Chapter 20, 245-258 Fourteenth Edition. Chapter 20, 245- 258 https://www-clinicalkey -com.gmulibrary.com/#!/content/book/3-s2.0- B9780323597128000205 Power-point presentation in the moodle www.gmu.ac.ae COLLEGE OF HEALTH SCIENCES