Mechanical Effects on Right Ventricular Function From Left Bundle Branch Block and Cardiac Resynchronization Therapy.

OBJECTIVES: The purpose of this study was to investigate how LBBB and CRT modify RV free wall function by direct ventricular interaction. BACKGROUND: Right ventricular (RV) function influences prognosis in patients with left bundle branch block (LBBB) and cardiac resynchronization therapy (CRT). There is, however, limited insight into how LBBB and CRT affect RV function. METHODS: In 24 patients with LBBB with nonischemic cardiomyopathy, RV and left ventricular (LV) strain by speckle-tracking echocardiography was measured before and after CRT. Underlying mechanisms were studied in 16 anesthetized dogs with ultrasonic dimension crystals and micromanometers. RESULTS: Patients with LBBB demonstrated distinct early systolic shortening in the RV free wall, which coincided with the typical abnormal early systolic septal shortening. In animals, this RV free wall contraction pattern resulted in reduced myocardial work as a large portion of the shortening occurred against low pressure during early systole, coinciding with abnormal leftward septal motion. RV systolic function was maintained by vigorous contraction in the late-activated LV lateral wall, which pushed the septum toward the RV. CRT reduced abnormal septal motion and increased RV free wall work because there was less inefficient shortening against low pressure. CONCLUSIONS: LBBB reduces workload on the RV free wall because of abnormal septal motion and delayed activation of the LV lateral wall. Restoring septal and LV function by CRT increases workload in RV free wall and may explain why patients with RV failure respond poorly to CRT. (Contractile Reserve in Dyssynchrony: A Novel Principle to Identify Candidates for Cardiac Resynchronization Therapy [CRID-CRT]; NCT02525185).

Heart failure with preserved ejection fraction. / Hjertesvikt med normal ejeksjonsfraksjon.

BACKGROUND: Approximately one half of all patients with heart failure have normal ejection fraction in the left ventricle, and heart failure is attributed to stiffness of the cardiac muscle. The most common cause is hypertension with ventricular hypertrophy. MATERIAL AND METHOD: Literature searches were conducted in PubMed. After we made our selection, a total of 15 articles on heart failure with normal ejection fraction were included. In addition, we included nine articles from our own literature archive. RESULTS: The diagnosis of heart failure with normal ejection fraction presupposes clinical findings consistent with heart failure and objective signs of diastolic dysfunction. The main objective sign is increased left ventricular filling pressure estimated by echocardiography. Ventricular hypertrophy and increased natriuretic peptides support the diagnosis. INTERPRETATION: Underlying conditions and symptoms are treated, and in general the same drugs are used as for heart failure with reduced ejection fraction.