His bundle electrograms were recorded in 13 patients before and 20 minutes after morphine administration. Recordings were made at various rates utilizing right atrial pacing. Morphine did not alter the HQ intervals. However there were variable effects on the AH intervals as well as on the effective refractory period of the AV node. These results can be explained by the interplay of two factors, catecholamine release and a direct depressant action of the drug. Conduction through the AV node will be improved or delayed, depending on which factor is dominant.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine