title: Hemodynamic effects of tachycardia in patients with relaxation abnormality: abnormal stroke volume response as an overlooked mechanism of dyspnea associated with tachycardia in diastolic heart failure.
abstract: BACKGROUND
  Prevention of tachycardia is an important therapeutic strategy in patients with relaxation abnormality.
  
  
  METHODS
  Eleven patients with stable relaxation abnormality (group 1) and 8 healthy individuals (group 2) were enrolled. Left ventricular (LV) mean diastolic pressure, LV dimensions, stroke volume (SV), and LV ejection, filling, and isovolumic times between right atrial pacing rates of 80 and 120/min were compared.
  
  
  RESULTS
  Both groups 1 and 2 showed significant decreases in LV mean diastolic pressure when heart rate (HR) increased. At a HR of 80/min, no significant difference was noted between groups 1 and 2 in SV (51.4 +/- 13.0 vs 45.2 +/- 9.0 mL, P = .35). However, a decrement in SV between a HR of 80 and 120/min was significantly greater for group 1. Therefore, group 1 showed a significantly lower SV (30.2 +/- 7.1 vs 40.1 +/- 6.9 mL, P < .05) at a HR of 120/min. In terms of time intervals between HRs of 80 and 120/min, group 1 showed a significantly greater reduction in LV ejection time (84.5 +/- 20.1 vs 30.0 +/- 34.6 milliseconds, P < .005) and a smaller reduction in LV filling time (106.4 +/- 38.5 vs 166.3 +/- 30.7 milliseconds, P < .005) than group 2.
  
  
  CONCLUSIONS
  Results of our study suggest that an inadequate SV response to tachycardia may play an important role in the production of dyspnea associated with tachycardia in these patients.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea. dwsohn@snu.ac.kr <dwsohn@snu.ac.kr>
authors.forename: Dae-Won
authors.initials: DW
authors.lastname: Sohn
authors.forename: Hyung-Kwan
authors.initials: HK
authors.lastname: Kim
authors.forename: Jin-Shik
authors.initials: JS
authors.lastname: Park
authors.forename: Hyuk-Jae
authors.initials: HJ
authors.lastname: Chang
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Kim
authors.forename: Zoo-Hee
authors.initials: ZH
authors.lastname: Zo
authors.forename: Byung-Hee
authors.initials: BH
authors.lastname: Oh
authors.forename: Young-Bae
authors.initials: YB
authors.lastname: Park
authors.forename: Yun-Shik
authors.initials: YS
authors.lastname: Choi
mesh_terms: D004417:Dyspnea / Q000175:diagnosis / Q000209:etiology*; D005260:Female; D006333:Heart Failure / Q000150:complications* / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000150:complications* / Q000000981:diagnostic imaging*; D014463:Ultrasonography; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology*