Can topical tetracaine cause tachycardia in patients, especially those with pre-existing heart conditions or other risk factors?

Can Topical Tetracaine Cause Tachycardia?

Topical tetracaine does not typically cause tachycardia; instead, it can cause bradycardia and other cardiac arrhythmias as part of local anesthetic systemic toxicity (LAST), though these events are extremely rare with an incidence of approximately 0.03%. 1

Understanding Tetracaine's Cardiac Effects

Tetracaine is an ester-type local anesthetic that, when absorbed systemically, primarily affects cardiac conduction and rhythm through sodium channel blockade rather than causing tachycardia. The cardiac manifestations of tetracaine toxicity include:

• Bradycardia and conduction abnormalities are the predominant cardiac effects, with arrhythmias including second-degree or higher atrioventricular conduction block occurring before progression to asystole 2
• A documented case in an extremely low birth weight premature infant demonstrated clinically significant bradycardia after topical tetracaine application, with no other identifiable cause, and the cardiac symptoms resolved with treatment 3
• Tetracaine's cardiotoxicity manifests as progressive conduction disturbances leading to arrhythmias and ultimately cardiac arrest (asystole), not tachycardia 2

Mechanism and Risk Factors

The cardiovascular effects of tetracaine differ fundamentally from agents that cause tachycardia:

• Tetracaine acts as a sodium channel blocker, similar to Class I antiarrhythmic drugs, which depresses cardiac conduction and contractility rather than stimulating heart rate 4
• Systemic absorption is typically minimal because tetracaine is short-acting and rapidly metabolized by the pseudocholinesterase system, leading to very limited systemic uptake under normal circumstances 1
• Enhanced cardiotoxicity occurs when nitric oxide synthesis is inhibited, with tetracaine showing a 2.0-fold increase in arrhythmia susceptibility compared to baseline 2

Clinical Context: When Cardiac Effects Occur

Serious cardiac events from topical tetracaine are exceptionally rare and typically require specific circumstances:

• Mucous membrane application poses the highest risk, with deliberate or inadvertent application causing status epilepticus and two pediatric deaths when tetracaine was combined with epinephrine and cocaine (TAC solution) 5
• The combination of tetracaine with epinephrine and cocaine may potentiate intrinsic toxicities through drug interactions, though this involves the vasoconstrictor components rather than tetracaine alone 5
• A retrospective study of 537 flexible bronchoscopies using topical tetracaine at doses up to 158 mg (8 times the recommended 20 mg maximum) reported no cardiac or neurologic events attributable to tetracaine 6

Important Clinical Distinctions

It is critical to distinguish tetracaine from other topical agents that can cause tachycardia:

• Topical phenylephrine and other vasoconstrictors cause significant hypertension through alpha-adrenergic stimulation, which may trigger reflex bradycardia (not tachycardia) unless patients are pretreated with atropine or glycopyrrolate 4
• When baroreceptor-induced bradycardia is blocked by anticholinergics, the hypertension from vasoconstrictors persists without the compensatory heart rate reduction, but this still does not produce primary tachycardia 4
• Antisialogogue agents like glycopyrronium bromide and atropine, which are often used alongside topical anesthetics during airway procedures, may produce significant tachycardia as a direct effect 4

Practical Recommendations

When using topical tetracaine in clinical practice:

• Monitor for bradycardia and conduction abnormalities rather than tachycardia, particularly in vulnerable populations such as premature infants 3
• Avoid application to mucous membranes where systemic absorption is dramatically increased 5
• If tachycardia occurs in a patient receiving topical tetracaine, investigate alternative causes including co-administered anticholinergics (atropine, glycopyrronium), anxiety, pain, or other medications 4
• The maximum recommended dose for topical tetracaine is 20 mg, though higher doses up to 158 mg have been used safely in bronchoscopy settings with appropriate monitoring 6
• Patients with previous allergic reactions to lidocaine may still experience systemic reactions to tetracaine, including neurotoxicity manifesting as convulsions and rigidity, though cross-reactivity between these different classes of local anesthetics is not well established 1