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KMID : 0378119830100010120
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Chungnam Medical Journal
1983 Volume.10 No. 1 p.120 ~ p.131
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Effects of Local Anesthetics on the Cardiac Function
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尹炳來/Youn, Byung Rae
崔世鎭/金光鎭/朴海根/Choi, Se Jin/Kim, Kwang Jin/Park, Hae Kun
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Abstract
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Local anesthetics are drugs that block the impulse conduction in nerves. Thus, they have been used clinically for the treatment of cardiac arrhythmia, but exact mechanism of their action on nerves and organs remains unknown.
The object of this study is to investigate the actions or mechanisms of local anesthetics; procaine, lidocaine, bupivacaine, and tetracaine, on the cardiovascular system and the cardiac contractility. For this study, eighty rabbits(average weight 2.0kg) were anesthetized with subcutaneous urethane(lg/kg wt.) for in vivo study and thirty six isolated turtle hearts for perfusion study were used.
The results are summarized as follows:
1. Local anesthetics, given intravenously, were increased the respiratory rate, and decreased the blood pressure and heart rate of rabbits. And the changes were proportional to the injected drug concentrations.
2. Severe arrhythmias were observed at high dosages in vivo and in vitro study
3. Local anesthetics professed were decreased the cardiac contractility, the conduction time, and
dC/dT in the isolated hearts, and their changes were proportional to the drug concentrations.
4. The correlation between the changes of the cardiac contractility and the conduction time in
the isolated heart was expressed as following equation: Contractility(%)=17.1-0.3conduction time(%). And the correlation coefficient(r=0.771) was statistically significant.
5. The correlation coefficients(r) between dC/dT and the conduction time or the cardiac contractility were 0.793 and 0.773 or 0.922 and 0.933, respectively. The values were statistically significant.
From the above results, it was suggested that the mechanism of action of local anesthetics is caused primarily by the reversible blockade of the impulse conduction resulted from the changes of the membrane permeability of ions in the cardiac muscle.
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