Chapter 8. Valvular Pathophysiology
In measuring the transvalvular gradient in aortic stenosis, which of the following is unacceptable?
A. Recording of left ventricular (LV) and aortic (Ao) pressures using a double-lumen catheter
B. Comparison of LV and Ao pressures from a pullback tracing in a patient in sinus rhythm
C. Matching the 2 aortic pressures before crossing the valve and after pullback
D. Obtaining pressures from the LV and femoral artery sheath
The goal is to obtain the difference in the pressures between the LV and Ao. In order to be sure there is no systematic error introduced into measurement by faulty transducer calibration or catheter lumen obstruction, identical pressures must be obtained when the catheters or both lumens of a double-lumen catheter are in the same hemodynamic location of the proximal aorta. A pullback accomplishes the same goal since it is a single catheter and is not compared to a second catheter whereby an error in either could cause a false gradient to be introduced into the system. However, using the LV and femoral artery for the recording sites automatically introduces the errors of nonsimultaneous recording and pressure recovery into the system and should be avoided.
Regarding the Gorlin formula, which of the following statements is false?
A. 44.3 in the denominator of the equation is the Gorlin constant for the aortic valve.
B. 44.3 is the empiric constant.
C. 44.3 is the constant of orifice contraction.
The value of 44.3 is the square root of 2 × the acceleration due to gravity (980 m/s/s; ie, 1960). The empiric constant of 0.85 was derived only for the mitral valve. The constant of orifice contraction has not been established for either valve.
Invasive determination of aortic valve area is appropriate in which of the following?
A. Echocardiographic Doppler estimate of a mean gradient of 20 mm Hg and an aortic valve area (AVA) of 0.9 cm2
B. Presence of a late-peaking systolic ejection murmur and an echocardiographic Doppler AVA of 0.8 cm2
C. A patient with syncope and an echocardiographic Doppler mean gradient of 60 mm Hg
D. An echocardiographic Doppler exam showing a heavily calcified ...