1. Inotropes in Cardiac Surgery

2. Basics

3. Cardiac Cycle Phase 1 - Atrial Contraction
Phase 2 - Isovolumetric Contraction
Phase 3 - Rapid Ejection
Phase 4 - Reduced Ejection
Phase 5 - Isovolumetric Relaxation
Phase 6 - Rapid Filling
Phase 7 - Reduced Filling

4. Sympathetic / Parasympathetic
Sympathetic
Parasympathetic
Heart
Chronotropy (rate)
+ + +
_ _ _
Inotropy (contractility)
  _
Dromotropy (conduction velocity)
+ +
Vessels (Vasoconstriction)
Resistance (vasoconstriction)
  0
Capacitance (venous volume)

5. Starlings Law

6. BEFORE INOTROPES Fluid Rhythm Tamponade Bleeding Pneumothorax
Bolus
Legs up
Rhythm
ECG, SR, slow, fast, paced on ventricle, ST’s, ectopics
Tamponade
CVP, BE, UO, temp, CXR, echo
Bleeding
Drains, CXR, Hb
Pneumothorax
CXR, examine, vent alarms
Fight Ventilator
Paralyse, sedate or extubate

7. Which Inotrope Ohms Law V=I x R BP=CO x SVR Simple terms
Low or high cardiac output, what is the PA pressure

8. Inotropes Atropine Ca2+ Dopamine Dopexamine Dobutamine Adrenaline
Noradrenaline
Isoprenaline
Enoximone
Aminophylline
Vasopressin
Methylene blue NO

9. Receptors

10. Atropine Antimuscurinic ie causes tachycardia
Some pateints have muscurinic receptors on ventricle as well ie inotropic
Increases HR
CO=SV x HR

11. Ca2+ Inotrope and vasoconstrictor Short acting
Beware radial artery patients
Warn patient if awake

12. Dopamine Acts on dopamine receptors on heart and kidney
Causes a tachycardia (CO=SV x HR)
Increases urine output in some patients
Less metabolic side effects compared with adrenaline
Beware patients with tachycardia (give k+, Mg2+)

13. Dopexamine Tachycardia Increase splanchnic and renal blood flow
VASODILATOR
Beware
Vasodilated patients

14. Dobutamine Like dopamine
Has less effect on pulmonary artery pressure good for mitral valve patients

15. Adrenaline Excellent inotrope but dirty
Increased heart rate and inotropy (ß1-adrenoceptor mediated)
Vasoconstriction in most systemic arteries and veins (postjunctional a 1 and a 2 adrenoceptors)
Vasodilation in muscle and liver vasculatures at low concentrations (b2-adrenoceptor); vasoconstriction at high concentrations (a1-adrenoceptor mediated)

16. Adrenaline

17. Noradrenaline Vasoconstrictor
Increased heart rate and increased inotropy (ß1-adrenoceptor mediated)
Vasoconstriction occurs in most systemic arteries and veins (postjunctional a 1 and a 2 adrenoceptors)
Ask can I wake patient up to avoid Norad
Must have a good cardiac output

18. Noradrenaline

19. Isoprenaline Causes tachycardia and vasodilatation
Good in patients with high PA pressures
Beware vasodilated patients

20. Enoximone Phosphodiesterase Inhibitor
Good in patients with high PA pressure
“2nd line when adrenaline having no effect “receptor dissociation”

21. Aminophylline Phosphodiesterase inhibitor
Main effect on lung compared to heart
Good in patients who have hypoxic vasoconstriction “short fat little smoker with poor urine output”

22. Vassopresin 2nd line vasoconstrictor Most powerful available
Associated with organ ischaemia

23. Methylene blue
Whatever the mechanism the final step of vasodilatation is NO
Methylene blue inhibits NO synthesis

24. Nitric Oxide

25. What else
IABP
LVAD
RVAD
BVAD