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Notes
      3. Old stuff
          3.2. Old physio stuff (around 2005)
              3.2.3. Physiology
                  3.2.3.2. Cardiovascular
                      3.2.3.2.2. Heart
 3.2.3.2.2.3. Heart pump 
 1. Left ventricular pressure-time curve
 2. Stroke volume
 3. Heart sounds

Heart pump

Determinants of cardiac performance

  • Heart rate
  • Stroke volume
    * Preload
    * Afterload
    * Contractility

Note:

  • Cardiac output not altered by primary changes in heart rate from about 40-50/min to 180/min.
  • Beyond this range, CO is rate-dependent.

Force of extrasystole beats

Premature heartbeat is weak, but the beat after the pause is strong because

  • Increased filling (acting via Frank-Starling mechanism)
  • Increased SR store of Ca2+ available for release
    * postextrasystolic potentiation

 

Other notes

[WG22:p692]

  • Hypocapnia increases cardiac output
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