F Valvular heart disease
Aortic stenosis
Disease of the aortic valve may present as aortic valvular stenosis, insufficiency, or a combination of both. Valvular heart disease is usually caused by rheumatic disease, but it may also occur secondary to calcific degeneration in elderly patients. Endocarditis and congenital abnormalities of the bicuspid valve account for most of the remainder. It is rarely possible to repair the aortic valve; therefore, most conditions require valve replacement.
Pathophysiology
Chronic obstruction to LV ejection results in concentric LV hypertrophy and myocardium that is highly susceptible to ischemia (even in the absence of coronary artery disease). Aortic stenosis is severe when the valve area is less than 0.6 cm2 and the pressure gradient is greater than 70 torr.
Hemodynamic goals
Left ventricular filling is dependent on atrial contractions, heart rate, and normal intravascular volume. Decreases in SVR are dangerous because of the fixed ventricular ejection; decreased SVR results in decreased blood pressure, coronary perfusion pressures, and resultant ischemia. Extreme and rapid increase in SVR increases LW workload and further decrease stroke volume through the stenotic aortic valve.
Dysrhythmias
Dysrhythmias should be aggressively treated. Because the ventricle is stiff, atrial contraction is critical for ventricular filling and stroke volume.
Anesthetic technique
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