The routine auxiliary examination for heart valve disease also includes three major components; Chest X-ray, electrocardiogram, and cardiac ultrasound, among which cardiac ultrasound is the key focus.
Next, let's talk about the ultrasound findings of patients with aortic valve stenosis?
1、 Echocardiography is the most useful detection method, which can determine the location of aortic outflow tract obstruction, estimate the severity of valve obstruction, and provide other information such as left ventricular function, left ventricular hypertrophy, left atrial size, and the presence or absence of related valve abnormalities;
2、 For cardiac ultrasound examination, what indicators need to be considered? Although the main manifestation of aortic valve stenosis is the reduction of the aortic valve orifice area. The importance of comprehensive evaluation that needs to be emphasized here is that overemphasizing a certain indicator can easily lead to incompleteness.
3、 For patients with active valve stenosis, ultrasound examination not only needs to focus on the valve area of the aortic valve, but other relatively important indicators include: flow velocity at the aortic valve opening, pressure gradient across the aortic valve, left ventricular ejection fraction, left ventricular size and wall thickness, and degree of calcification of the aortic valve.
In addition, overemphasizing the importance of cardiac ultrasound is also one-sided. In theory, it is necessary to comprehensively evaluate the patient's symptoms, physical examinations such as blood pressure, heart murmurs, and other auxiliary examinations such as chest X-rays and electrocardiograms.
An important aspect of ultrasound evaluation for aortic valve stenosis is to assess the severity of the stenosis. Generally speaking, there are several indicators that can be used as criteria for classification:
1. Aortic valve area
2. Average pressure step
3. Aortic jet blood flow velocity
Among these indicators, theoretically accurate calculation of valve area is crucial. The measurement of valve area can be calculated through continuous equations or estimated through plane geometry methods.
If the calculated valve area by ultrasound examination is less than 1.0cm2, it indicates severe aortic valve stenosis. Considering that the original valve area may vary among individuals, the body surface area can be calculated based on height and weight before correction. If the ratio of valve area to body surface area is less than 0.6cm2/m2, it is also considered severe aortic stenosis.
The other two indicators are transvalvular pressure gradient and the highest blood flow velocity through the site of aortic valve stenosis, which is not difficult to understand. After all, the narrower the valve, the greater the pressure gradient and the faster the passage speed, which can also reflect the severity of aortic valve stenosis to a certain extent.
There are two indicators of transvalvular pressure gradient, namely the average transvalvular pressure gradient and the maximum transvalvular pressure gradient (peak transvalvular step gradient). These two are different, as can be seen from their names, and we will not explain them further here.
Doppler measurement estimates the transvalvular pressure gradient by measuring the blood flow through the aortic valve. The measurement results have a good correlation with cardiac catheterization examination. Usually, a peak transvalvular gradient greater than 64mmHg or an average transvalvular gradient greater than 40mmHg indicates the presence of severe aortic valve stenosis.
It should be pointed out that pressure gradient can change in different situations, and many factors can affect transvalvular pressure gradient. Specific influencing factors include exercise, medication, anemia, insufficient blood volume, concomitant aortic valve insufficiency, and left ventricular systolic function. Therefore, in ultrasound evaluation, it is necessary to emphasize continuous observation and collect multiple measurement data to comprehensively evaluate the degree of aortic valve stenosis;
In conclusion, echocardiography is an important tool for diagnosing and evaluating aortic valve stenosis. The preferred method for evaluating aortic valve stenosis is to confirm the stenosis, assess the cause of the stenosis, the degree of calcification, left ventricular function and wall thickness, detect the presence of other valve damage, and provide prognostic information. When evaluating the condition of patients with aortic valve stenosis using echocardiography, multiple indicators should be combined, including aortic valve velocity, pressure gradient across the aortic valve, aortic valve area, left ventricular ejection fraction, left ventricular size and wall thickness, and degree of calcification of the aortic valve.