Thursday, December 20, 2007

Assessing mechanical cardiac asynchrony

E-Journal - Volume 6 - Assessing mechanical cardiac asynchrony

Assessing mechanical cardiac asynchrony by echography

Dr. B. Vidal and *Dr J. Brugada Barcelona, Spain*Chairman of the European Heart Rhythm Association

Assessing mechanical cardiac asynchrony by echography could enable a better use of cardiac resynchronisation therapy in patients with advanced heart failure.

Mechanical cardiac asynchrony : definition

Mechanical cardiac asynchrony is defined as the presence of a delayed contraction of certain myocardial segments.
It usually appears at the end stage of a number of different cardiac diseases, together with left ventricular (LV) dilatation and systolic dysfunction.Mechanical cardiac asynchrony may or may not be associated with electrical asynchrony which is present in up to 30% of patients with heart failure, expressed mainly as a left bundle branch block (LBBB) in the surface ECG. The presence of mechanical intraventricular asynchrony contributes to aggravating LV hemodynamics , favors the apparition of functional mitral regurgitation and consequently, worsens the patient’s prognosis.

Mechanical asynchrony classes
Mechanical asynchrony can be found at the following three levels: atrioventricular, interventricular and intraventricular level. They can coexist and may be measured by echography.

Atrioventricular asynchrony consists of the decoordination of auricular contraction regarding LV filling due to an electrical conductance disturbance.

Interventricular asynchrony refers to the decoordination between right and LV contraction. Physiologically LV contraction occurs 10 to 20 ms later than the right ventricle; when this time difference is superior to 40 ms, this indicates interventricular asynchrony.

Intraventricular Asynchrony The decoordination of the contraction sequence in the different LV segments determines the presence of intraventricular asynchrony

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