The normal electrical cardiac activation sequence is required for optimal left ventricular (LV) contraction and efficient pump function. Pacing that is conducted at virtually any ventricular site disturbs the natural activation pattern and ventricular contraction because the applied impulse travels slowly through the myocardium rather than through the rapidly conducting His-Purkinje system. Thi...

AIMS Cardiac resynchronization therapy (CRT) improves functional capacity and survival in heart failure. However, one-third of patients fail to respond to CRT. Resting left ventricular (LV) dyssynchrony assessed by echocardiography (ECHO) showed discordant results in identifying CRT responders. LV dyssynchrony can totally change during exercise. Aim of this study was to evaluate whether exercis...

This article discusses how echocardiography can be applied to quantify dyssynchrony in patients who are evaluated for cardiac resynchronization therapy (CRT). A number of echocardiographic indices have been proposed as markers of success of CRT. However, when tested against QRS width in prospective clinical trials, none of the echocardiographic indices are proven to give clinical benefit. One i...

Correction of mechanical dyssynchrony is believed to be the primary mechanism by which cardiac resynchronization therapy (CRT) improves clinical status and reduces left ventricular (LV) volume.1 The use of QRS duration as a surrogate for mechanical dyssynchrony has been intensely investigated, based on the suspicion that a direct measurement of mechanical rather than electric dyssynchrony might...

Cardiac resynchronisation therapy (CRT) is an established therapy for patients with heart failure with wide QRS duration. Recent studies observed that assessment of systolic dyssynchrony is an important diagnostic tool as the treatment involves the re-coordination of regional wall contraction within the left ventricle. Therefore, the effectiveness of CRT depends heavily on whether systolic dyss...

point for selecting candidates to CRT. However, one issue still remains: what is the best predictive echocardiographic method (among the different Doppler tissue imaging techniques) for selecting those patients? This requires larger studies comparing the positive and negative predictive values of several techniques already published. From this point, it can be emphasized that heart failure pati...

Aims: Mechanical dyssynchrony has been reported in heart failure with preserved ejection fraction (HFpEF), with a majority of patients having a narrow QRS complex; however, whether any benefit is observed with restoration of dyssynchrony remains unclear. We sought to assess left ventricular (LV) dyssynchrony and function in HFpEF and elucidate the underlying mechanisms that may account for HFpE...

OBJECTIVES This study sought to test a novel echocardiographic method based on contrast variability imaging (CVI), to quantify cardiac dyssynchrony and magnitude of resynchronization achieved by left ventricular (LV) and biventricular (BiV) pacing therapy. BACKGROUND Left ventricular or BiV pacing is a promising new therapy for patients with heart failure and intraventricular conduction delay...

Multiple echocardiographic criteria have been proposed to diagnose mechanical dyssynchrony in patients with heart failure without being validated against a model of cardiac dyssynchrony with heart failure. This study examines which of these methods can detect dyssynchrony in a canine model. Adult mongrel dogs underwent His-bundle ablation and right-ventricular pacing for 4 wk at either 110 bpm ...