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CARDIODYNAMICS

CARDIODYNAMICS. KEY. EDV = End-diastolic volume. ESV = End-systolic volume. Stroke volume. 120. D. ESV. 80. C. One cardiac cycle. Left ventricular pressure (mm Hg). 40. EDV. B. A. 0. 65. 100. 135. Left ventricular volume ( mL ). Cardiac Cycle.

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CARDIODYNAMICS

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  1. CARDIODYNAMICS

  2. KEY EDV = End-diastolic volume ESV = End-systolic volume Stroke volume 120 D ESV 80 C One cardiac cycle Left ventricular pressure (mm Hg) 40 EDV B A 0 65 100 135 Left ventricular volume (mL) Cardiac Cycle Left ventricular pressure-volume changes during one cardiac cycle Figure 14-25

  3. KEY EDV = End-diastolic volume ESV = End-systolic volume 120 80 Left ventricular pressure (mm Hg) 40 A 0 65 100 135 Left ventricular volume (mL) Cardiac Cycle Figure 14-25 (1 of 4)

  4. KEY EDV = End-diastolic volume ESV = End-systolic volume 120 80 Left ventricular pressure (mm Hg) 40 EDV B A 0 65 100 135 Left ventricular volume (mL) Cardiac Cycle Figure 14-25 (2 of 4)

  5. KEY EDV = End-diastolic volume ESV = End-systolic volume 120 80 C Left ventricular pressure (mm Hg) 40 EDV B A 0 65 100 135 Left ventricular volume (mL) Cardiac Cycle Figure 14-25 (3 of 4)

  6. KEY EDV = End-diastolic volume ESV = End-systolic volume Stroke volume 120 D ESV 80 C One cardiac cycle Left ventricular pressure (mm Hg) 40 EDV B A 0 100 65 135 Left ventricular volume (mL) Cardiac Cycle Figure 14-25 (4 of 4)

  7. Stroke Volume and Cardiac Output • Stroke volume • Amount of blood pumped by one ventricle during a contraction • EDV – ESV = stroke volume.(135 mL - 65 mL = 70 mL) • Cardiac output(Cardiac Output Is a Measure of Cardiac Performance) • Volume of blood pumped by one ventricle in a given period of time • CO = HR  SV • CO = 72 beats/min x 70 mL/beat • = 5040 mL/min (or approx. 5/L min) • Average = 5 L/min

  8. Ejection Fraction – is the fraction of the end-diastolic volume that is ejected with each beat, that is, it is stroke volume (SV) divided by end-diastolic volume (EDV), is a commonly used measure of cardiac performance. stroke volume / end diastole volume X 100%, normal range, 55-65%.

  9. Factors Affecting Cardiac Output-Allfactors that control HR and SV will influence CO physiology

  10. Factors Affecting Heart rate 1. Autonomic innervation • Sympathetic stimulus increases heart rate Ex. During fight or flight response • Parasympathetic stimulation decreases heart rate. Ex. Relaxation techniques 2. Hormones • Epinephrine : Increases heart rate Tachycardia= Resting HR> 100 beats/min Bradycardia=Resting HR<60 beats/min physiology

  11. Stroke Volume • Force of contraction • Stroke volume • Affected by length of muscle fiber and contractility of heart • Frank-Starling law • Stroke volume increase as EDV increases • EDV determined by venous return • Skeletal muscle pump • Respiratory pump • Sympathetic innervation

  12. Stroke Volume Length-force relationships in intact heart: a Starling curve Figure 14-28

  13. Factors that Affect Cardiac Output Figure 14-31

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