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Effects of halothane, sevoflurane and desflurane on the force-frequency relation in the dog heart in vivo

[Les effets de l’halothane, du sévoflurane et du desflurane sur la relation force-fréquence des curs de chiens in vivo]

Benedikt Preckel, MD DEAA^*,, Detlef Obal, MD DESA^,, Jost Müllenheim, MD DEAA, Juliane Hennes, MD^¶, Marc Heiderhoff, MD^¶, Volker Thämer, MD^¶ and Wolfgang Schlack, MD DEAA^*,

^* From the Department of Anesthesiology, Academic Medical Center, University of Amsterdam, The Netherlands;
Department of Anesthesiology, University Hospital of Duesseldorf, Germany;
Department of Anesthesiology, University of Louisville, Louisville, Kentucky, USA; the
South Tyneside District Hospital, South Shields, UK; and the
^¶ Institute for Physiology, University of Duesseldorf, Germany.

Address correspondence to: Dr. Benedikt Preckel, Associate Professor, Academic Medical Center, University of Amsterdam, Postbus 22660 H1Z-139, 1100 DD Amsterdam, The Netherlands. Phone: +31-20-5662533; Fax: + 31-20-6979441; E-mail: b.preckel{at}amc.uva.nl

Purpose: Frequency potentiation is the increase in force of contraction induced by an increased heart rate (HR). This positive staircase phenomenon has been attributed to changes in Ca²⁺ entry and loading of intracellular Ca²⁺ stores. Volatile anesthetics interfere with Ca²⁺ homeostasis of cardiomyocytes. We hypothesized that frequency potentiation is altered by volatile anesthetics and investigated the influence of halothane (H), sevoflurane (S) and desflurane (D) on the positive staircase phenomenon in dogs in vivo.

Methods: Dogs were chronically instrumented for measurement of left ventricular (LV) pressure and cardiac output. Heart rate was increased by atrial pacing from 120 to 220 beats·min^–1 and the LV maximal rate of pressure increase (dP/ dt_max) was determined as an index of myocardial performance. Measurements were performed in conscious dogs and during anesthesia with 1.0 minimal alveolar concentrations of each of the three inhaled anesthetics.

Results: Increasing HR from 120 to 220 beats·min^–1 increased dP/dt_max from 3394 ± 786 (mean ± SD) to 3798 ± 810 mmHg sec^–1 in conscious dogs. All anesthetics reduced dP/dt_max during baseline (at 120 beats·min^–1: H, 1745 ± 340 mmHg·sec^–1; S, 1882 ± 418; D, 1928 ± 454, all P < 0.05 vs awake) but did not influence the frequency potentiation of dP/dt_max (at 220 beats·min^–1: H, 1981 ± 587 mmHg·sec^–1; S, 2187 ± 787; D, 2307 ± 691). The slope of the regression line correlating dP/dt_max and HR was not different between awake and anesthetized dogs. Increasing HR did not influence cardiac output in awake or anesthetized dogs.

Conclusion: These results indicate that volatile anesthetics do not alter the force-frequency relation in dogs in vivo.