From the Guidelines
Yes, radiation exposure can cause hypotensive or syncopal events, particularly in cases of acute radiation syndrome or during radiation therapy. These cardiovascular effects typically occur through several mechanisms, including damage to blood vessels leading to vasodilation and decreased vascular resistance, resulting in blood pressure drops, as well as effects on the autonomic nervous system disrupting normal blood pressure regulation 1. In radiation therapy patients, these events may occur due to a vasovagal response triggered by anxiety, pain, or the treatment position. Acute radiation syndrome from high-dose exposure can cause more severe hypotension as part of the prodromal phase, where nausea, vomiting, and fluid losses compound cardiovascular instability.
Key Mechanisms and Effects
- Radiation can damage blood vessels, leading to vasodilation and decreased vascular resistance, which results in blood pressure drops.
- It can also affect the autonomic nervous system, disrupting normal blood pressure regulation.
- In cases of acute radiation syndrome, symptoms such as disorientation, confusion, prostration, loss of balance, and seizures can occur, accompanied by physical examination findings like papilledema, ataxia, and reduced or absent deep tendon and corneal reflexes 1.
Management Considerations
- Management includes positioning patients in a reclined position during treatments, ensuring adequate hydration, monitoring vital signs, and in some cases, providing prophylactic medication for patients with a history of vasovagal episodes.
- The risk of these events varies based on the radiation dose, exposure area (particularly when the heart or brain is in the radiation field), and individual patient factors such as age and pre-existing cardiovascular conditions.
- It's crucial to consider the clinical responses for all syndromes related to radiation exposure and to use a grading system to assess the severity of symptoms and guide management decisions 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Radiation and Hypotensive/Syncopal Events
- There is evidence to suggest that radiation therapy can cause cardiovascular disease, including conditions that may lead to hypotensive or syncopal events 2, 3.
- Radiation-induced cardiovascular disease can manifest as accelerated atherosclerosis, valvular disease, pericardial involvement, and autonomic dysfunction 2.
- Autonomic dysfunction, which can be caused by radiation therapy, can lead to orthostatic hypotension, a condition characterized by a decrease in blood pressure upon standing, which can cause symptoms such as lightheadedness, dizziness, and syncope 4, 5, 6.
- A study found that mediastinal radiation therapy decreased vagal and sympathetic autonomic nervous system activities, and autonomic balance shifted toward sympathetic dominance, which can increase the risk of hypotensive or syncopal events 6.
- While there is no direct evidence that radiation causes hypotensive or syncopal events, the available evidence suggests that radiation-induced cardiovascular disease and autonomic dysfunction can increase the risk of these events 2, 6, 3.