No patients showed a cardioinhibitory
response in this study.
There was a lower observed rate of overall neurocardiogenic syncope, and specifically, lower rates of a mixed and cardioinhibitory
response in our black patients undergoing tilt-table testing.
The mother, age 35, showed a cardioinhibitory response (type IIb) on HUT, while the father, age 41, showed a cardioinhibitory response without asystole (type IIa).
Hence, HUT limits greatly the number of candidates for pacemaker therapy since a cardioinhibitory response occurs in about 10% of patients.
Dual-chamber pacing in treatment of neurally-mediated tilt-positive cardioinhibitory syncope.
Mechanisms include central vagal effects likely via the cardioinhibitory
parasympathetic vagal neurons in the nucleus ambiguous (1) and the effect on vagal nerve endings and cardiac opiate receptors (2).
For example there are PMKs that can activate some algorithms for the treatment of neuromediated cardioinhibitory
syncope (for example the function RDR--Rate Drop Response) or to look for the spontaneous AV conduction in order to decrease the percentage of right ventricular pacing (Medtronic MVP Minimal Ventricular Pacing).
At the heart, the response to cardioinhibitory
nerve stimulation is quicker than that to cardioacceleratory nerve stimulation.
No cardioinhibitory responses of greater than 3 s were documented.
The cardioinhibitory respose is abolished by atropine which affords definition of the vasodepressor response independent to heart rate slowing .
Responses were grouped into predominantly cardioinhibitory, predominantly vasodepressor or a mixed response; the latter if patients had a significant cardioinhibitory response and vasodepressor response independent of cardioinhibition.
Of these, three patients had a predominantly cardioinhibitory response, 17 had a predominantly vasodepressor response and nine a mixed response.