Aortic stenosis
Grading severity
Just memorize the moderate cutoffs (25 to 40mmHg), anything below is mild, above is severe
- thickened LV caused by pushing against a fixed outlet
- CPP = DBP - LVEDP
- Avoid hypotension: hypertrophied LV means increased LVEDP, higher O2 demand
- Avoid bradycardia: essentially “fixed” SV → CO is HR dependent → slow HR siginficantly reduces CO
- Avoid Tachycardia: Tachycardia inreases oxygen demand, shortens diastole (when LV is perfused) → decr coronary perfusion pressure
- Pressor of choice: Phenylephrine → for incr BP and relative bradycardia
Aortic regurgitation
- Regurgitation happens during diastole, when the AV should be closed
- Relative tachycardia: incr HR → decr time in diastole → minimize regurgitation
- Improve forward flow and decr LVEDP with vasodilators, decr SVR
- Induction goals: maintain relative tachycardia and incr DBP to maintain CPP
- Pressor of choice: Epi or Norepi
Mitral stenosis
Almost always rheumatic in origin. Incr left atrial pressure may cause AFib and pulmonary edema
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Elevated LA pressure → incr pulmonary venous pressure and PVR → pHTN → TR, RV failure
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Avoid tachycardia: MS → less LV filling for a given time → tachycardia shorter diastole → less filling → decr CO
- Continue any digoxin, CCB, BB perioperatively
- chemically or electrically cardiovert any AFib
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Avoid pHTN: O2, hypocarbia, alkalosis, nitrates, veletri/iNO all decr PVR
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Hypotension: may indicate RV failure and/or need for inotropes or pulmonary vasodilators
Mitral regurgitation
Caused by mitral valve prolapse (myxomatous degeneration), ischemic heart disease, pap rupture
- MR allows blood to backflow from LV to LA during systole, EF usually overestimated as regurgitant fraction not accounted for
- Relative tachycardia: is desirable to decr ventricular filling time
- Afterload reduction: incr SVR → worsens regurg causing more regurg as LA lower resistance
- Maintain preload: Very preload dependent as SV only partially ejected