Tissue doppler imaging in hypertrophic cardiomyopathy without left ventricular hypertrophy

Area of Science:

• Cardiology
• Genetics
• Diagnostic Imaging

Background:

• Diastolic dysfunction detected by Doppler echocardiography, particularly tissue velocity imaging, may identify carriers of abnormal genes for hypertrophic cardiomyopathy (HCM).
• These carriers may not yet exhibit clinical evidence of the disease.

Purpose of the Study:

• To evaluate the utility of tissue Doppler imaging in detecting subclinical carriers of a cardiac myosin-binding protein C gene mutation.
• To assess if Doppler-derived diastolic function parameters can differentiate gene carriers from non-carriers in an HCM family.

Main Methods:

• Seven carriers and eight non-carriers of the cardiac myosin-binding protein C gene mutation were studied using 2-D, M-mode Doppler, and tissue Doppler imaging.
• Measurements included basal wall thickness and left ventricular inspection for hypertrophy. Tissue Doppler peak systolic and early diastolic velocities at the mitral annulus were analyzed.

Main Results:

• No localized hypertrophy was observed in either group.
• Significant differences in tissue Doppler velocities were found, especially in early diastole.
• A systolic velocity <10 cm/s combined with mitral E velocity <14 cm/s indicated gene positivity. Mitral E velocity >14 cm/s was exclusive to gene-negative individuals.

Conclusions:

• Tissue Doppler imaging shows promise as a screening tool for first-degree relatives of HCM patients.
• This technique can detect individuals with the genetic predisposition for HCM who lack evident disease on standard 2-D echocardiography.