title: Estimation of preload recruitable stroke work relationship by a single-beat technique in humans.
abstract: The slope of the preload recruitable stroke work relationship (M(w)) is a highly linear, load-insensitive contractile index. To investigate whether M(w) can be determined from a single steady-state beat, 45 patients were studied during cardiac catheterization. Single-beat M(w) (SBM(w)) was calculated directly from the baseline stroke work and baseline left ventricular (LV) end-diastolic volume (EDV(B)), and the volume-axis intercept (V(w)) was estimated as k x EDV(B) + (k - 1) x LV(wall), where k is the ratio of the epicardial shell volumes corresponding to V(w) and EDV(B) and LV(wall) is the wall volume. The mean of individual k values was 0.72 +/- 0.04, which correlated with LV mass significantly (r = 0.60, P < 0.001). SBM(w) calculated from a constant k of 0.7 predicted M(w) well (r = 0.88, P < 0.0001), and the prediction improved slightly when k was estimated from individual LV mass (r = 0.93, P < 0.0001). Subgroup analyses revealed that the single-beat technique also worked in patients with small or large LV mass or volume or with regional wall motion abnormalities. The absolute change in SBM(w) after dobutamine infusion also correlated with that in M(w). In conclusion, M(w) can be estimated from a steady-state beat without alteration of preload.
authors.affiliation: Division of Cardiology, Taipei Veterans General Hospital, National Yang-Ming University, Taiwan, Republic of China.
authors.forename: Wen-Shin
authors.initials: WS
authors.lastname: Lee
authors.forename: Wen-Pin
authors.initials: WP
authors.lastname: Huang
authors.forename: Wen-Chung
authors.initials: WC
authors.lastname: Yu
authors.forename: Kuan-Rau
authors.initials: KR
authors.lastname: Chiou
authors.forename: Philip Yu-An
authors.initials: PY
authors.lastname: Ding
authors.forename: Chen-Huan
authors.initials: CH
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002316:Cardiotonic Agents / Q000494:pharmacology; D004280:Dobutamine / Q000494:pharmacology; D005260:Female; D006334:Heart Function Tests; D006706:Homeostasis; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D010496:Pericardium / Q000502:physiology; D013318:Stroke Volume
chemical_list: D002316:Cardiotonic Agents; D004280:Dobutamine