title: Further insights into blood pressure induced premature beats: Transient depolarizations are associated with fast myocardial deformation upon pressure decline.
abstract: BACKGROUND
  An acute increase in blood pressure is associated with the occurrence of premature ventricular complexes (PVCs).
  
  
  OBJECTIVE
  We aimed to study the timing of these PVCs with respect to afterload-induced changes in myocardial deformation in a controlled, preclinically relevant, novel closed-chest pig model.
  
  
  METHODS
  An acute left ventricular (LV) afterload challenge was induced by partial balloon inflation in the descending aorta, lasting 5-10 heartbeats (8 pigs; 396 inflations).
  
  
  RESULTS
  Balloon inflation enhanced the reflected wave (augmentation index 30% ± 8% vs 59% ± 6%; P < .001), increasing systolic central blood pressure by 35% ± 4%. This challenge resulted in a more abrupt LV pressure decline, which was delayed beyond ventricular repolarization (rate of pressure decline 0.16 ± 0.01 mm Hg/s vs 0.27 ± 0.04 mm Hg/ms; P < .001 and interval T-wave to peak pressure 1 ± 12 ms vs 36 ± 9 ms; P = .008), during which the velocity of myocardial shortening at the basal septum increased abruptly (ie, postsystolic shortening) (peak strain rate -0.6 ± 0.5 s(-1) vs -2.5 ± 0.8 s(-1); P < .001). It is exactly at this time of LV pressure decline, with increased postsystolic shortening, and not at peak pressure, that PVCs occur (22% of inflations). These PVCs preferentially occurred at the basal and apical segments. In the same regions, monophasic action potentials demonstrated the appearance of delayed afterdepolarization-like transient depolarizations as origin of PVCs.
  
  
  CONCLUSIONS
  An acute blood pressure increase results in a more abrupt LV pressure decline, which is delayed after ventricular repolarization. This has a profound effect on myocardial mechanics with enhanced postsystolic shortening. Coincidence with induced transient depolarizations and PVCs provides support for the mechanoelectrical origin of pressure-induced premature beats.
authors.affiliation: Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Peter
authors.initials: P
authors.lastname: Haemers
authors.affiliation: Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: George
authors.initials: G
authors.lastname: Sutherland
authors.affiliation: Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Maja
authors.initials: M
authors.lastname: Cikes
authors.affiliation: Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Nina
authors.initials: N
authors.lastname: Jakus
authors.affiliation: Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Patricia
authors.initials: P
authors.lastname: Holemans
authors.affiliation: Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Karin R
authors.initials: KR
authors.lastname: Sipido
authors.affiliation: Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium.
authors.forename: Rik
authors.initials: R
authors.lastname: Willems
authors.affiliation: Department of Cardiovascular Sciences, KU Leuven, Leuven, Belgium. Electronic address: piet.claus@med.kuleuven.be.
authors.forename: Piet
authors.initials: P
authors.lastname: Claus
mesh_terms: D000818:Animals; D018780:Body Surface Potential Mapping; D005117:Cardiac Complexes, Premature / Q000175:diagnosis / Q000209:etiology; D004195:Disease Models, Animal; D015150:Echocardiography, Doppler; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006973:Hypertension / Q000150:complications*; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D009200:Myocardial Contraction / Q000502:physiology*; D011312:Pressure; D011897:Random Allocation; D012680:Sensitivity and Specificity; D034421:Sus scrofa; D013599:Systole / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*; D018879:Ventricular Premature Complexes / Q000175:diagnosis / Q000209:etiology*
keywords: Blood pressure; Mechanoelectrical coupling; Postsystolic shortening; Premature ventricular complex