**The Trigeminocardiac Reflex — An Example of Reflexive Heart Rhythm Change**

Tumul Chowdhury, Belachew Arasho, Nora Sandu, Cyrill Meuwly and Bernhard Schaller

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/60215

#### **Abstract**

[71] Brignole M, Auricchio A, Baron-Esquivias G, et al. 2013 ESC guidelines on cardiac pacing and cardiac resynchronization therapy: the task force on cardiac pacing and resynchronization therapy of the European Society of Cardiology (ESC). Developed in collaboration with the European Heart Rhythm Association (EHRA). Europace

[72] Dandamudi G, Rampurwala AY, Mahenthiran J, et al. Persistent left ventricular dila‐ tation in tachycardia-induced cardiomyopathy patients after appropriate treatment

[73] Brill IC. Auricular fibrillation with congestive failure and no other evidence of organ‐

[74] David M, Rothman S, Shapiro T. First reported case of recurrent tachycardia-induced

[75] Cheruvu C, Walker B, Kuchar D, Subbiah RN. Successful ablation of incessant AV re‐ entrant tachycardia in a patient on extracorporeal membrane oxygenation. Heart Lung Circ 2014 Jan;23(1):e12–5. doi: 10.1016/j.hlc.2013.06.011. Epub 2013 Aug 6. [76] Chugh SS, Shen WK, Luria DM, Smith HC. First evidence of premature ventricular complex-induced cardiomyopathy: a potentially reversible cause of heart failure. J

[77] Singh B, Sudan D, Kaul U. Radiofrequency ablation for bundle branch reentrant ta‐ chycardia in a patient with aortic valve replacement and left ventricular dysfunction.

[78] Yu YH, Bilezikian JP. Tachycardia-induced cardiomyopathy secondary to thyrotoxi‐ cosis: a young man with previously unrecognized Graves' disease. Thyroid

[79] Chang-Chretien K, Chew JT, Judge DP. Reversible dilated cardiomyopathy associat‐

[80] Cognet T, Lairez O, Marchal P, et al. A family history of dilated cardiomyopathy in‐ duced by viral myocarditis. Case Rep Cardiol 2012;2012:204371. doi:

[81] Khasnis A, Jongnarangsin K, Abela G, et al. Tachycardia-induced cardiomyopathy: a

review of literature. Pacing Clin Electrophysiol 2005 Jul;28(7):710–721.

and normalization of ejection fraction. Heart Rhythm 2008;5(8):1111–1114.

cardiomyopathy due to atrial flutter. QJM 2014 May;107(5):383–386.

2013 Aug;15(8):1070–1118.

94 Abnormal Heart Rhythms

ic heart disease. Am Heart J 1937;13:175–182.

Cardiovasc Electrophysiol 2000;11(3):328–329.

ed with glucagonoma. Heart 2004;90(7):e44.

10.1155/2012/204371. Epub 2012 Feb 27.

Indian Heart J 1998;50(5):551–553.

2000;10(10):923–927.

The trigeminocardiac reflex (TCR) is defined as the sudden onset of parasympathetic dysrhythmia, sympathetic hypotension, apnoea or gastric hyper-motility during mechanical/thermal stimulation of any of the sensory branches of the trigeminal nerve. The risk factors that are already known for increasing the prevalence of the TCR include anatomical location, hypercapnia, hypoxemia, light general anaesthesia, age (more pronounced in children), the nature of the provoking stimulus (stimulus strength and duration) and different drugs. Already different potential confounders are also identified. This discussion about risk factors has its importance because of the substantial consequences for functional outcome after intraoperative TCR occurrence. But there remains still a substantial lack of thorough understanding of the TCR, the current treatment options for patients with TCR include a mostly empirical approach: (i) risk factor identification and modification; (ii) prophylactic measures of vital signs and (iii) administration of vagolytic agents or sympathomimetics. In this context, we have now created different thinking models so that we can preoperatively plan a skull base surgery procedure safely in relation to a potential occurrence of the TCR episodes. This chapter provides an overview of this unique reflex that presents a unique interaction between heart and brain. In addition, this also illustrates the mechanism of various cardiac rhythm changes related to the TCR.

**Keywords:** Atropine, trigeminocardiac reflex, oculocardiac reflex, skull base surgery, treatment, trigeminal nerve, study design, evidence

© 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

## **1. Introduction**

The fifth cranial nerve is the largest of all the cranial nerves and provides sensory supply to the face, scalp, sinus and mucosa of the nose and mouth as well as the dura mater of the middle, anterior and part of the posterior cranial fossa [1–3]. Stimulation of any of these sensory parts of trigeminal nerve has been shown to initiate the trigeminocardiac reflex (TCR) and also produce various cardiac arrhythmias besides other less life-threatening symptoms [1, 3, 4, 5]. Initially, this reflex has been studied in animals and is therefore known for more than a century [6–8], under the term of "trigemino-respiratory reflex" and now its revival as sudden infant death syndrome (SIDS). In the early 20th century, the TCR has gained much clinical and less experimental attention in the form of the oculocardiac reflex (OCR) which is the predominant cardiac response associated with the stimulation of the ophthalmic division of the trigeminal nerve during ocular surgeries [9, 10]. Then later, Schaller et al., for the first time, demonstrated that the TCR occurred with the stimulation of the intracranial portion of the trigeminal nerve as well [1]. In addition, Schaller and his group later sub-summarized all these reflexes under the term TCR [2, 11], what is now generally accepted. Since then, there have been extensive discussions about the reflex itself, about the prophylaxis or risk factors, about treatment and about the influence of the TCR on functional outcome when it occurs during the intracranial or the extra-cranial procedures. Schaller and his group could demonstrate the ubiquitary occurrence of this reflex in any skull base procedure during 20 last years.

The TCR also serves as an important interaction between brain and heart, and thus provides deeper understanding of mechanisms related to various cardiac changes related to various extra/intracranial surgeries [4, 12–16]. The TCR represents as a model for different other diseases like, for example, sudden infant death syndrome (SIDS). Therefore, this chapter highlights the various aspects of TCR including its definition, epidemiology, risk factors and management. Special consideration is given to illustrate the mechanism of various cardiac rhythm changes related to the TCR.
