How can hypertension/high blood pressure cause bradycardia?

Several mechanisms : Hypertension (HTN) can resulting in ischemia and abnormality of the conduction system of the heart which may slow heart rate. After a head injury HTN and a slow heart rate are signs that there may be increase in intra-cranial pressure. There is also a phenomena where correcting a slow heart rate might resolve HTN see link below. http://www.ncbi.nlm.nih.gov/pubmed/7457024 edit.