From the Guidelines
The normal range for aortic transvalvular peak pressure gradient measured with Doppler by transthoracic echocardiography (TTE) is typically less than 20 mmHg. A normal, healthy aortic valve should allow blood to flow from the left ventricle to the aorta with minimal resistance, resulting in a small pressure difference across the valve. Values between 20-40 mmHg suggest mild aortic stenosis, 40-70 mmHg indicates moderate stenosis, and greater than 70 mmHg represents severe aortic stenosis. These measurements are derived from the modified Bernoulli equation (pressure gradient = 4v²), where v is the peak velocity of blood flow across the aortic valve, as described in the European Heart Journal study 1.
The peak pressure gradient is an important parameter in evaluating aortic valve function, as increased gradients reflect greater resistance to blood flow, which can lead to left ventricular hypertrophy and heart failure if severe and untreated. It's essential to interpret these measurements in the clinical context, considering other echocardiographic parameters such as valve area, mean gradient, and left ventricular function. The American College of Cardiology/American Heart Association guidelines also support the use of mean gradient and jet velocity to classify the severity of aortic stenosis, with severe stenosis generally having a mean transvalvular pressure gradient greater than 40 mmHg 1.
Key points to consider when evaluating aortic transvalvular peak pressure gradient include:
- The modified Bernoulli equation is used to calculate the pressure gradient
- A normal, healthy aortic valve should have a peak pressure gradient less than 20 mmHg
- Values between 20-40 mmHg suggest mild aortic stenosis, 40-70 mmHg indicates moderate stenosis, and greater than 70 mmHg represents severe aortic stenosis
- Other echocardiographic parameters, such as valve area and left ventricular function, should be considered in the clinical context.
From the Research
Aortic Transvalvular Peak Pressure Gradient
The normal range for aortic transvalvular peak pressure gradient measured with Doppler by TTE is not explicitly stated in the provided studies. However, the studies provide information on the measurement of transvalvular pressure gradient in patients with aortic stenosis.
Measurement of Transvalvular Pressure Gradient
- The study 2 validated a reduced-order model method for assessing transvalvular pressure gradient (TPG) in aortic stenosis using CT data, with a mean TPG of 48.0 ± 26 mmHg.
- The study 3 compared TTE and LCC assessments of aortic stenosis severity, with a mean trans-AV systolic ejection pressure gradient (MSEPG) of 20 - <40 mm Hg for moderate aortic stenosis and ≥40 mm Hg for severe aortic stenosis.
- The study 4 compared TTE and CMR for the estimation of effective orifice area in aortic stenosis, with a good correlation between TTE-derived and CMR-derived EOAs.
- The study 5 analyzed the decision to intervene in patients with severe aortic stenosis, with a lower transaortic mean gradient associated with a decision not to intervene.
- The study 6 compared TTE and TEE assessments of mitral and aortic regurgitation, with modest agreement between the two methods.
Limitations
- The studies provided do not explicitly state the normal range for aortic transvalvular peak pressure gradient measured with Doppler by TTE.
- The studies focus on patients with aortic stenosis, and the results may not be applicable to healthy individuals.
- The measurement of transvalvular pressure gradient can be affected by various factors, including the method used and the patient's condition.