4. Cardiac function
• Inotropy or Contractility: Loss systolic HF
• Lusitropy or Relaxibility: Loss Diastolic HF (HFpEF)
• Chronotropy or Automaticity :Loss loss of
underlying rhythm
• Dromotropy or conductivity :Loss 2nd or 3rd HB
• Bathmotropy or Excitability : Loss more in paediatric
as primary rhythm disorder , (tapping the heart )
F.Aljanadi
22. PRELOAD
• Represents by the end-diastolic ventricular volume;
• Represents the ventricle filling .
• Influenced by
LV compliance
Blood volume
Atrial systole
Length of diastole
Factors that affect this relationship, such as mitral stenosis
and ventricular hypertrophy, will affect preload.
• The Frank-Starling curve
Frank-Starling relationship
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24. CONTRACTILITY
• Ability of the myocardium to pump blood without changes
in preload or afterload;
• Influenced by
intracellular calcium concentrations
the autonomic nervous system
humoral changes
pharmacological agents. Metabolites ,Co2, hypoxia
• A sudden increase in contractility with unchanged preload
and afterload will result in increased stroke volume by
ejecting more volume out of the ventricle .
F.Aljanadi
25. AFTERLOAD
• The pressure the ventricle must overcome to eject a volume of blood
past the aortic valve.
• Afterload is most often equated with ventricular wall tension. Represents
by end-systolic pressure .
• Influenced by :
SVR
LVOT,AV area
LV wall stress (tension)
LaPlace’s law: Circumferential stress = Pr/Th
where circumferential stress is the wall tension, P: intraventricular pressure,
r :ventricular radius, and Th: wall thickness.
wall tension is the primary determinant of oxygen consumption.
hypertrophy or thickening of the ventricular wall
as a result of or to compensate for systolic failure, the ventricle will
dilate.
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30. Oxygen Consumption and CBF
• Heart weighs about 300 g or approx. 0.5% of the total body mass
• Oxygen demand of the heart accounts for 7% of the resting body oxygen
consumption , 5% of the cardiac output.
• The normal myocardial oxygen consumption MVO2 per minute is approx.
8 mL O2/100 g .
• The MVO2 is primarily dependent on the coronary blood flow (CBF) and the
removal of oxygen from the coronary blood as follows: Arterial (CaO2) contents
minus Venous (coronary sinus, CSO2) contents:
MVO2 = CBF × (CaO2- CSO2)
CBF = CPP/CVR
CPP=DBP-LVEDP
Poiseuille’s Law = ∆P / R
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40. Parameters
F.Aljanadi
120 kg M Post
CABG oozing
CVP almost 0
with BP 100/60
HR 120 bpm on
vasopressors
and SVR in
maximal limits
.What is SV ?
What’s next
step?
41. CO
• Fick principle 1870
• Thermodilution
• Doppler ultrasound
• Pulse contour analysis
• Bioimpedance
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