Reflex bradycardia is a bradycardia (decrease in heart rate) in response to the baroreceptor reflex, one of the bodys homeostatic mechanisms for preventing abnormal increases in blood pressure. In the presence of high mean arterial pressure, the baroreceptor reflex produces a reflex bradycardia as a method of decreasing blood pressure by decreasing cardiac output.Blood pressure (BP) is determined by cardiac output (CO) and total peripheral resistance (TPR), as represented by the formula BP = CO x TPR. Cardiac output (CO) is affected by two factors, the heart rate (HR) and the stroke volume (SV), the volume of blood pumped from one ventricle of the heart with each beat (CO = HR x SV, therefore BP = HR x SV x TPR). In reflex bradycardia, blood pressure is reduced by decreasing cardiac output (CO) via a decrease in heart rate (HR).An increase in blood pressure can be caused by increased cardiac output, increased total peripheral resistance, or both. The baroreceptors in the carotid sinus sense this increase in blood pressure and relay the information to the cardiovascular centres in the medulla oblongata. In order to maintain homeostasis, the cardiovascular centres activate the parasympathetic nervous system. Via the vagus nerve, the parasympathetic nervous system stimulates neurons that release the neurotransmitter acetylcholine (ACh) at synapses with cardiac muscle cells.
Often, the cause can be ascertained without performing tests.When blood tests are requested, they usually include thyroid tests and prolactin to rule out hypothyroidism and hyperprolactinemia. Other tests that may be considered include mammography, breast ultrasound, CT scan of the head to rule out a pituitary tumour, breast biopsy, x-ray imaging of breast ducts or skin biopsy.The absence of cancerous cells in samples of nipple discharge does not exclude cancer, hence cytology of the nipple discharge is not usually performed. However, guidance on investigations varies and tests are more likely performed if the discharge is bloody, from one breast, and the woman is age over 50. If the test is performed and malignant cells are found, an underlying cancer is highly likely. Treatment
Initially, an evaluation for cancer is indicated. Treatment will depend on the cause found, and may involve changing medication, having a lump removed, applying a cream to treat a skin condition or being given medication to treat the condition causing the discharge. Duct ectasia may be treated with surgical removal of the ducts involved. Infectious causes may require antibiotics and/or incision and drainage. Sometimes, no treatment is required.If no abnormality is found, a surgical duct excision may resolve the symptoms. Treatment also depends on whether single-duct or multiple-duct discharge is present, and whether the symptoms of nipple discharge are distressing to the person. In some cases, there may be no need for any further intervention; in others, microdochectomy or a total duct excision may be appropriate.