2) The peak pressure Emergent surgical gradient was 30 mmHg, treatment and the

mean gradient was 20 mmHg.

Her preoperative transthoracic echocardiogram revealed an ejection fraction of 60%, aortic valve area of 0.5 [cm.sup.2],

mean gradient of 59 mm Hg, and left ventricular outflow tract area of 1.7 cm.

Transthoracic echocardiogram (TTE) confirmed severe AS (

mean gradient 40 mmHg; aortic valve area 0.8 [cm.sup.2]), concomitant moderate aortic regurgitation, and preserved left ventricular function (ejection fraction 55%).

An echocardiogram was performed during her first prenatal care visit showing a heart rate of 61 bpm, peak velocity of 360.5 m/s, peak gradient across valve of 52 mmHg,

mean gradient across valve of 28.9 mmHg, and dimensionless index 0.36.

Aortic stenosis was defined as follows: mild (aortic jet velocity of 2.0-2.9 m/s and a peak systolic gradient and a

mean gradient of <36 mmHg and <20 mmHg, resp.), moderate (aortic jet velocity of 3.0-4.0 m/s and a peak systolic gradient and a

mean gradient of 36-64 mmHg and 20-40 mmHg, resp.), and severe (aortic jet velocity of >4 m/s and a peak systolic gradient and a

mean gradient of >64 mmHg and >40 mmHg, resp.).

The wash-in rate was defined as the

mean gradient between the two time points of [t.sub.onset] and the maximum intensity:

Severe AS is considered to exist when the peak velocity [greater than or equal to] 4 m/s, the

mean gradient [greater than or equal to] 40 mmHg, and AVA is <1 [cm.sup.2].

According to current American College of Cardiology/American Heart Association guidelines, cut-off values for Doppler-echocardiographic measurements of severe aortic stenosis are defined as follows: aortic valve area (AVA) less than 1.0 cm2,

mean gradient >40 mm Hg, and peak velocity >4.0 m/s.1 Symptomatic severe disease often caused by age-related calcium deposition is universally fatal if left untreated, yet is consistent with a typical lifespan when mechanical relief of the stenosis is provided in a timely fashion.

Transthoracic echocardiogram (TTE) showed an ejection fraction of 62%, severely stenotic aortic valve, with

mean gradient of 75 mmHg and a peak gradient of 104 mmHg.

The

mean gradient remained stable at 12.4mmHg at 24 months, compared to 12.6mmHg at 30 days.

Besides the series of 43 patients quoted above, there is the report of a 68 year old man with a mechanical aortic prosthesis who had stopped oral anticoagulants 3 months after surgery and was seen 23 years later with an audible prosthetic valve click and a

mean gradient of 19mm.