Estimation of preload recruitable stroke work relationship by a single-beat technique in humans.
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.
Lee
Wen-Shin
WS
Division of Cardiology, Taipei Veterans General Hospital, National Yang-Ming University, Taiwan, Republic of China.
Huang
Wen-Pin
WP
Yu
Wen-Chung
WC
Chiou
Kuan-Rau
KR
Ding
Philip Yu-An
PY
Chen
Chen-Huan
CH
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
D002316:Cardiotonic Agents; D004280:Dobutamine