Electromechanical dyssynchrony and resynchronization of the failing heart Journal Article

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Authors: Kirk, J. A.; Kass, D. A.
Article Title: Electromechanical dyssynchrony and resynchronization of the failing heart
Abstract: Patients with heart failure and decreased function frequently develop discoordinate contraction because of electric activation delay. Often termed dyssynchrony, this further decreases systolic function and chamber efficiency and worsens morbidity and mortality. In the mid- 1990s, a pacemaker-based treatment termed cardiac resynchronization therapy (CRT) was developed to restore mechanical synchrony by electrically activating both right and left sides of the heart. It is a major therapeutic advance for the new millennium. Acute chamber effects of CRT include increased cardiac output and mechanical efficiency and reduced mitral regurgitation, whereas reduction in chamber volumes ensues more chronically. Patient candidates for CRT have a prolonged QRS duration and discoordinate wall motion, although other factors may also be important because approximately 30% of such selected subjects do not respond to the treatment. In contrast to existing pharmacological inotropes, CRT both acutely and chronically increases cardiac systolic function and work, yet it also reduces long-term mortality. Recent studies reveal unique molecular and cellular changes from CRT that may also contribute to this success. Heart failure with dyssynchrony displays decreased myocyte and myofilament function, calcium handling, beta-adrenergic responsiveness, mitochondrial ATP synthase activity, cell survival signaling, and other changes. CRT reverses many of these abnormalities often by triggering entirely new pathways. In this review, we discuss chamber, circulatory, and basic myocardial effects of dyssynchrony and CRT in the failing heart, and we highlight new research aiming to better target and implement CRT, as well as leverage its molecular effects.
Journal Title: Circulation research
Volume: 113
Issue: 6
ISSN: 1524-4571; 0009-7330
Publisher: Unknown  
Journal Place: United States
Date Published: 2013
Start Page: 765
End Page: 776
Language: eng
DOI/URL:

10.1161/CIRCRESAHA.113.300270
Notes: LR: 20141112; GR: HL-112586/HL/NHLBI NIH HHS/United States; GR: HL-114910/HL/NHLBI NIH HHS/United States; GR: P01 HL077180/HL/NHLBI NIH HHS/United States; GR: P01-HL077180/HL/NHLBI NIH HHS/United States; GR: P50 HL084946/HL/NHLBI NIH HHS/United States; GR: T32-HL07227/HL/NHLBI NIH HHS/United States; JID: 0047103; NIHMS520802; OID: NLM: NIHMS520802; OID: NLM: PMC3874431; OTO: NOTNLM; ppublish