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Now We’re Pumping!
The Physiology Behind Myocardial
Performance
International Conference of PeriAnesthesia
Nursing
Toronto, Canada Tuesday, 4th, 2011
Kim A. Noble, Ph.D., RN, CPAN
[email protected]
My Little Angels
A Duplex
Blood Flow Through the Heart
 Venous return
 Rt ventricular filling
 Ejection to lungs
 Return from lungs
 Lt ventricular filling
 Ejection to body
www.pbs.org/wgbh/nova/heart/heartmap.html
Cardiac Anatomy
Valves & Chambers
Chambers:
Atria
Ventricles
http://www.harunyahya.com/books/science/blood_hea
rt/images/heart_valves.jpg
Valves:
AV valves
Semilunar valves
Cardiac Muscle
Cardiac Conduction System
Autometicity
Conductivity
Excitability
http://www.cvphysiology.com/Arrhythmias/conduction%20syste
m%20anatomy.gif
 SA Node
 AV Node
 Bundle of His
 Purkinje Fibers
http://www.msjc.edu/pic/224/ekg.gif
Na+/K+ ATPase: The Beginning
K+
+
K
K+
Na+
Na++
Na
Myocyte Contraction
 Na+/K+ ATPase
 Ca++ ATPase
 Na++ Extruder



http://www.nature.com/nature/journal/v415/n6868/images/415198a-f1.2.jpg
Coronary Blood Flow
Epi.
Myocardium
Endo.
http://www.cvphysiology.com/Blood%20Flow/BF001_coronary_flow.gif
Myocyte Oxygen Extraction
Vascular Structure
• Arteries
– Tunica Intima
– Tunica Media
– Tunica Adventica
• Capillaries
• Veins
www.nurse.perscriber.co.uk/education/visual_l...
Blood Flow Distribution
http://www.mfi.ku.dk/PPaulev/chapter8/images/8-1.jpg
Ventricular Pressure-Volume Relationship
• LVP: Left ventricular
pressure.
• LVV: Left ventricular
volume.
• Upper graph is represented
over time.
• Lower graph is a
pressure/volume curve.
http://www.cvphysiology.com/Cardiac%20Function/CF024%20PV%20loop.gif
Wigger’s Curves

Phases of the cardiac cycle:
 Filling phase
 Isovolumetric contraction
 Ejection
 Isovolumetric relaxation
 Filling phase







Mitral valve closes
Aortic valve opens
Aortic valve closes
Mitral valve opens
http://www.pharmacology2000.com/cardiac/gore4_Wiggers4A.gif
Cardiac Cycle
http://kuwaitmd.hsc.edu.kw/main/files/Cardiac_Cycle_Left_Ventricle.PNG
Cardiac Performance: Cardiac Output
Cardiac Output (L/min)
Heart Rate (beats/min)
Stroke Volume (ml/min)
CO = HR X SV
Determinates of Stroke Volume
• Preload
• Contractility
• Afterload
btc.montana.edu/olympics/physiology/cf04.html
Ejection Fraction
Measure of cardiac
efficiency.
http://www.nismat.org/physcor/eject_fract.gif
Autonomic Stimulation
Sympathetic Stimulation
Parasympathetic Stimulation
1 +1=?
Energetic Implications
CO = HR SV
SNS
• SV:
Preload (venous)   SV $
Contractility 
$
Afterload (arterial)   SV $
• HR:
SA firing 
Conduction velocity 
PSNS
http://treadthis.com/exercise-busy-schedule.bmp
$
$
Alpha Receptors
• Alpha 1:
– Vascular smooth muscle
– Also eye (dilation)
– Also bladder (retention)
• Alpha 2:
– Control gates for Alpha 1
receptors.
Beta Receptors:
• Beta 1:
– [1 heart]  heart rate,
 conduction velocity &
 CO.
• Beta 2:
– [2 lungs] Bronchodilation
– Also vasoconstriction &
uterine relaxation.
Muscarinic Receptors
http://abdellab.sunderland.ac.uk/lectures/Parmacology/Pics/graphics/AChE.jpg
Adrenergic Receptors
http://www.mc.uky.edu/pharmacology/instruction/decor/ar/nervterm.jpg
Summary of Cardiac ANS Effects
SNS
PSNS
Chronotropy: Rate 

Dromotropy: Conductivity 


Inotropy: Contraction 
Lusitropy: Relaxation 

http://www.cvphysiology.com/Blood%20Pressure/BP010%20c
ardiac%20receptors.gif
Autonomic Stimulation
SNS Stimulation:
– β- 1 (NE):
•  HR (2 effects)
•  Contractility
– β- 2 (E): Lungs
– α- 1 & α- 2 (NE):
•  Afterload &  Preload
(vasoconstriction)
PSNS Stimulation:
– Muscarinic Receptors (ACh):
•  HR
•  Contractility
• Vasodilation  Afterload &
 Preload
anatomy.med.umich.edu/…/NS_Overview_11.html
References
• Berne, R. M. & Levy, M. N. (2001).
Cardiovascular physiology, 8th ed, St.
Louis, MO: Mosby.
• Guyton,
• Mohrman, D. E. & Heller, L. J. (1997).
Cardiovascular Physiology, 4th ed, New
York: McGraw Hill.
• Porth, C. M. & Matfin, G. (2009).
Pathophysiology: Concepts in Altered
Health States, 8th ed, Phila: Lippincott
Williams & Wilkins.