title: Resynchronization improves heart-arterial coupling reducing arterial load determinants.
abstract: BACKGROUND
  Cardiac resynchronization therapy (CRT) has benefits on left ventricle (LV) performance, but its mid-term effects on LV load and LV-arterial coupling are unknown.
  
  
  OBJECTIVE
  To evaluate CRT mid-term effects on LV-arterial coupling, arterial load and its determinants, and the association between CRT-dependent aortic haemodynamic changes and the arterial biomechanics.
  
  
  RESULTS
  Cardiac and aortic echographies were done in 25 patients (age: 61 ± 12 years; 14 men; New York Heart Association functional classes III-IV; LV ejection fraction = 28 ± 7%, QRS = 139 ± 20 ms) before and after (23 ± 12 days) CRT. Standard structural and functional parameters and dyssynchrony indices were evaluated. Ascending aorta flow and diameter waveforms were measured. Central pressure was derived using a transfer function and the diameter calibration method. Calculus: arterial elastance (EA); aortic impedance (Zc) and distensibility (AD); systemic resistances (SVR), total compliance (CT); global reflection coefficient; LV end-systolic elastance (EES); and LV-arterial coupling (EA/EES). After CRT EA diminished (-30%;P = 0.001), EES increased (29%; P = 0.001) and EA/EES improved (pre-CRT: 2.9 ± 0.9, post-CRT: 1.6 ± 0.7; P = 0.001). Arterial elastance changes were associated with changes in arterial properties. Cardiac resynchronization therapy was associated with pressure-independent increase in mean aortic diameter (pre-CRT: 30.0 ± 4.0 mm, post-CRT: 33.0 ± 5.1 mm; P = 0.005) and distensibility (pre-CRT: 3.8 ± 2.6 × 10(-3)mmHg(-1), post-CRT: 6.4 ± 2.5 × 10(-3) mmHg(-1); P = 0.002), and Zc reduction (pre-CRT: 3.5 ± 1.8 × 10(-2)mmHg.s/mL, post-CRT:1.9 ± 0.8 × 10(-2) mmHg.s/mL; P = 0.001) and SVR (pre-CRT:1.7 ± 0.4 mmHg.s/mL, post-CRT:1.0 ± 0.3 mmHg.s/mL; P = 0.001). Changes in EA determinants were associated with changes in aortic flow.
  
  
  CONCLUSIONS
  Early after CRT central and peripheral arterial biomechanics improved, determining a pressure-independent increase in aortic diameter and a reduction in arterial load. Left ventricular systolic performance and LV-arterial coupling were enhanced. Arterial biomechanical changes were associated with aortic flow changes.
authors.affiliation: Physiology Department, Centro Universitario de Investigación, Innovación y Diagnóstico Arterial (CUiiDARTE), School of Medicine, Universidad de la República, General Flores 2125, Montevideo PC: 11800, República Oriental del Uruguay. yana@fmed.edu.uy
authors.forename: Yanina
authors.initials: Y
authors.lastname: Zócalo
authors.forename: Daniel
authors.initials: D
authors.lastname: Bia
authors.forename: Ricardo L
authors.initials: RL
authors.lastname: Armentano
authors.forename: Juan
authors.initials: J
authors.lastname: González-Moreno
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Varela
authors.forename: Fernando
authors.initials: F
authors.lastname: Calleriza
authors.forename: Walter
authors.initials: W
authors.lastname: Reyes-Caorsi
mesh_terms: D000368:Aged; D001011:Aorta / Q000000981:diagnostic imaging / Q000503:physiopathology*; D062186:Arterial Pressure; D001696:Biomechanical Phenomena; D001794:Blood Pressure; D058406:Cardiac Resynchronization Therapy; D015150:Echocardiography, Doppler; D004548:Elasticity; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D006339:Heart Rate; D006439:Hemodynamics; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D011237:Predictive Value of Tests; D013318:Stroke Volume; D013997:Time Factors; D016896:Treatment Outcome; D014655:Vascular Resistance; D016277:Ventricular Function, Left