Effects of high dose narcotics and controlled hypotensors on the heart conduction system
Shen, J.F.; Xi, Y.Q.; Cao, Z.E.; Fu, C.Z.
Chinese Medical Journal 98(10): 743-748
1985
ISSN/ISBN: 0366-6999 PMID: 3938701 Document Number: 243837
The effects of narcotics on the heart conduction system were studied in 51 rabbits. It was found that at equal efficacy dosages, the effects of high dose morphine, pethidine and fentanyl on the heart conduction system differ. Morphine 3 mg/kg injected iv did not influence the heart conduction system; fentanyl 30 .mu.g/kg might improve both sinus node automaticity and sino-atrial conduction and pethidine 30 .mu.g/kg might seriously harm the heart conduction system. So fentanyl may be an ideal narcotic in patients with sick sinus syndrome. But when the dosage of fentanyl was increased to 75 .mu.g/kg, the sinus node was inhibited. The degree of pethidine effect upon the heart conduction system depends upon the dose and rate of injection. The effects of controlled hypotensors on the heart conduction system were studied in 48 dogs. Trimethaphan (TMTP), sodium nitroprusside (SNP) nitroglycerin (NG) and phentolamine (PA) were dripped iv respectively to lower the blood pressure by 30-40%. Five and 60 minutes after TMTP administration the atrio-ventricular junction was inhibited and at 60 minutes the sino-atrial conduction was also inhibited. NG had no influence on the heart conduction system but SNP might inhibit the sinus node automaticity PA may also inhibit the sinoatrial conduction, so this agent is contraindicated in patients with sick sinus syndrome or sino-atrial block.