Dyssynchronie

Dyssynchronie, or dyssynchrony, denotes a lack of synchronized timing between two or more components of a system. In biology and medicine the term is commonly used to describe asynchronous activity within the heart, where different regions fail to contract in a coordinated manner. Dyssynchrony can be mechanical, electrical, or a combination of both, and may arise from structural disease, conduction disturbances, or external pacing.

In cardiology, ventricular dyssynchrony refers specifically to asynchronous contraction of the heart ventricles or regions within a ventricle. It is often caused by conduction disturbances such as left bundle branch block or by chronic pacing from pacemakers or defibrillators. This desynchronization can reduce the efficiency of cardiac pumping, lower stroke volume, and worsen symptoms in patients with heart failure. Interventions are aimed at restoring synchrony and improving hemodynamics.

Types of cardiac dyssynchrony include interventricular dyssynchrony (timing differences between the left and right ventricles) and intraventricular dyssynchrony (timing differences within the same ventricle). Diagnosis relies on a combination of electrocardiography, which assesses electrical timing (for example, QRS duration), and imaging techniques such as echocardiography with tissue Doppler or speckle-tracking to evaluate mechanical timing. Magnetic resonance imaging can also contribute in some cases.

Management focuses on addressing the underlying cause and improving synchrony. Medical therapy for heart failure is foundational, and cardiac resynchronization therapy (CRT) with biventricular pacing is a key option for selected patients with reduced ejection fraction and evidence of dyssynchrony. The goal is to improve cardiac efficiency, symptoms, and outcomes. Not all patients respond to CRT, so patient selection and device optimization are important.