Problem: In Systole (cannot eject)Increase or maintain, maintain stroke volume (SV), avoid venodilation – maintain SVR
Extremes are not tolerated well. A-fib causes loss of atrial kick. Bradycardia will decrease CO due to fixed SV. Tachycardia will cause decreased CPP and ischemia
Maintain constant
Normal to high. Afterload is a stenotic valve. Increased SVR = Increased LVEDP and/or LVEDV = Increased MVO2
Maintain constant
3 leaflets
2.5-3.5 cm2
Peak gradient <10 mmHg
Aortic Stenosis
Angina - 5 yr survival
Syncope - hypoperfusion
Dyspnea/CHF - 2 yr survival
A-fib
Narrow pulse pressure <50
NYHA class III and IV
Valve area < 0.9 cm2, LV hypertrophic
Aortic valve gradient > 50mmHg
§ LV concentric hypertrophy
§ Increased LVEDP, LVEDV, LAP > 25-30 mmHg
§ Increased LA contribution to LV filling
§ Increased MVO2
§ Decreased O2 delivery = ischemia
§ Pulmonary HTN
§ RV failure
§ Angina, syncope, dyspnea
§ Systolic ejection click, holosystolic harsh murmur radiation to carotids. Diminished carotid pulses
§ EKG
§ LVH
§ AV- conduction blocks
§ ECHO to determine the size, severity, and pulmonary HTN
Measure gradient
Calculate valve area/valve morphology
Light premeds
Monitor hemodynamics
Prophylactic antibiotics (teeth/ infection)
GA- Regional (HOTN)
Phenylephrine gtt mixed
Myocardial protection difficult
Hypertrophied ventricle – cardioplegia ante grade / or retrograde via LV vent (via pulmonary veins as aorta open)
Cardiopulmonary bypass temperature 25-28 degrees C
Maintain preload
SR - avoid tachycardia/bradycardia
Inotropic support (inadequate protection leads to poor revascularization)
Avoid increased afterload
Mechanical
Tissue