Blood pressure can be seriously elevated during botulinum toxin A detrusor injection

Botulinum toxin A detrusor injection (BoNT/A-DI) is used in patients with overactive bladder (OAB) or neurogenic bladder due to multiple sclerosis (MS) or after spinal cord injury. The procedure is generally performed under local anaesthesia. We examined the influence of BoNT/A-DI on blood pressure, the most important autonomic parameter in awake patients, as a potential risk factor for cardiovascular events.

Patients with OAB or spontaneous voiding with neurogenic detrusor overactivity (NDO) due to MS in whom BoNT/A-DI was planned under local anaesthesia, vital parameters (systolic, diastolic, and mean blood pressure; heart rate; and rate pressure product [RPP]) were recorded before, during, and after the procedure. Participants with and without previously known hypertension were compared, along with those with initial versus repeat injections, with a focus on the high-risk group, which comprised the 20% of patients with the highest baseline blood pressure values.

Seventy patients were included (mean age: 64.0, median age: 66, range: 27-86 years), and two were excluded because their initial blood pressure values were too high. Sixty patients had OAB, and eight had NDO due to MS; twenty-two patients had a history of hypertension. A total of 40 patients received the first injection, and 28 received a repeat injection. Systolic blood pressure increased significantly by an average of 9.8 mmHg. However, in the hypertensive patients, systolic blood pressure rose by an average of 19.4 mmHg; isolated peak systolic values rose by up to 232 mmHg, and peak diastolic values rose by up to 128 mmHg. Cardiac stress (measured by rate pressure product [RPP]) in these patients increased significantly (RPP = 17.6 versus 7.2 in the non-hypertensive group). In the 20% of patients with the highest resting blood pressure values, systolic blood pressure rose to an average of 187.4 mmHg (15.1 mmHg compared with resting blood pressure), and cardiac workload increased by 17. No significant differences were observed between patients who received initial and repeat injections.

Clinicians who administer BoNT/A-DI should monitor blood pressure during the procedure and be aware of the risk of potentially significantly elevated blood pressure values during BoNT/A DI, especially in patients with a medical history of hypertension. Significantly elevated pre-interventional blood pressure values should receive an internal medicine consultation timely before the intervention to prevent cardiovascular risks.