From the Guidelines
Bradycardia after cardiac catheterization is primarily caused by vasovagal reactions, medication effects, and pre-existing conduction system disease, which can be exacerbated by the procedure. The risks of bradycardia after cardiac procedures are largely related to the type of procedure and the anatomical location, as noted in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Causes of Bradycardia
- Vasovagal reactions: Manipulation of the catheter can stimulate the vagus nerve, leading to a slowing of heart rate.
- Medication effects: Sedatives or anesthetics used during the procedure can depress the sinoatrial node function.
- Pre-existing conduction system disease: The procedure can exacerbate underlying conditions, such as sinus node dysfunction or atrioventricular blocks.
- Contrast media reactions: May trigger bradycardia in some patients.
Treatment and Management
- Close monitoring
- Atropine (0.5-1mg IV) for symptomatic bradycardia
- Temporary pacing if necessary
- Addressing any electrolyte imbalances Most cases are transient and resolve spontaneously, but persistent bradycardia may require further evaluation, as suggested by the guidelines 1. Patients with risk factors, such as advanced age or pre-existing heart disease, should be monitored more closely after the procedure.
From the FDA Drug Label
Atropine-induced parasympathetic inhibition may be preceded by a transient phase of stimulation, especially on the heart where small doses first slow the rate before characteristic tachycardia develops due to paralysis of vagal control Adequate doses of atropine abolish various types of reflex vagal cardiac slowing or asystole The drug also prevents or abolishes bradycardia or asystole produced by injection of choline esters, anticholinesterase agents or other parasympathomimetic drugs, and cardiac arrest produced by stimulation of the vagus.
The FDA drug label does not answer the question.
From the Research
Causes of Bradycardia after Cardiac Catheterization
- Bradycardia can occur during cardiac catheterization due to various factors, including catheter manipulation and the use of certain medications 2, 3.
- The study by 2 reported two cases of bradycardia during transradial cardiac catheterization, which were resolved by removing the catheter.
- Another study by 3 found that the combined use of beta-blocking agents and sodium channel blockers can cause severe iatrogenic bradycardia.
- The incidence of cardiac arrhythmias, including bradycardia, during cardiac catheterization has been reported in various studies, with some procedures carrying a higher risk than others 4.
Risk Factors and Procedures
- The risk of bradycardia and other cardiac arrhythmias may be higher during certain procedures, such as percutaneous coronary interventions for stable coronary artery disease or acute myocardial infarctions 4.
- The use of intravenous adenosine and papaverine bolus for fractional flow reserve measurement, as well as intracoronary imaging using optical coherence tomography, has been reported to induce ventricular fibrillation, which may also be associated with bradycardia 4.
- The study by 5 highlights the importance of evidence-based practices in the cardiac catheterization laboratory, including the use of appropriate medications and techniques to minimize the risk of complications such as bradycardia.
Mechanisms and Treatment
- The exact mechanisms of bradycardia during cardiac catheterization are not fully understood, but may involve the stimulation of aortic arch receptors and/or carotid sinus receptors by the catheter 2.
- Treatment of bradycardia during cardiac catheterization may involve the removal of the catheter, as well as the use of medications such as atropine or adrenergic agonists, and temporary pacing in severe cases 2, 3.