家兎脳底槽内への薬剤注入による心電図の変化

抄録

Abnormalities in ECG frequently occurring in patients associated with cerebrovascular lesions, especially subarachnoid hemorrhage, have been documented in many reports. Similar abnormalities in ECG have also been reported on such experiments as following electric stimulation of various sites of the brain, direct intracranial injection of space taking substances or induced ICP elevation.
Drugs are currently administered commonly by injection into the cisterna magna o r via the transorbital approach, however approach to the circle of Willis is difficult by either method or hemorrhage due to puncture of adjacent vessels may frequently occur. The author produced in rabbits a method injecting small amounts of drugs via the craniopharyngeal duct into the basal cistern with reduced surgical damage and minimal influences on the systemic circulation.
1. Direct administration of 0.5ml or less of physiological saline into the basal cistern of the rabbit via craniopharyngeal duct produced no changes in the systemic circulation or ECG.
2. Withdrawal of 1.0ml of cerebrospinal fluid from the craniopharyngeal duct and subsequent injection of serotonin (10mg-1.0ml) induced no changes in ECG except bradycardia.
3. When prostaglandin F_2α (500pg-0.5ml) was injected into the basal cistern, supraventricular and ventricular arrhythmia were observed in ECG after a mean interval of 301sec. ± 74sec., and S-T depression and lower T wave remained for more than 45 minutes. An increase i n blood pressure and a decrease in the heart rate were also noted.
4. Intravenous administration of the same dose of PGF2a caused no changes in ECG except bradycardia.
5. Injection of the same dose into the basal cistern after cervical spinal cord transection at the C₂-C₃ level induced no changes in ECG.
6. Thus the stimulation by the injection of PGF2a was shown to be conducted down to the heart via the cervical spinal cord.
7. A decrease in PaCO₂ was observed following injections of serotonin or PGF_2α into the basal cistern.