Isolated junctional tachycardia in a patient with pheochromocytoma: an unusual presentation of an uncommon disease

Sinus Tachycardia: a Multidisciplinary Expert Focused Review

Sinus tachycardia (ST) is ubiquitous, but its presence outside of normal physiological triggers in otherwise healthy individuals remains a commonly encountered phenomenon in medical practice. In many cases, ST can be readily explained by a current medical condition that precipitates an increase in the sinus rate, but ST at rest without physiological triggers may also represent a spectrum of normal. In other cases, ST may not have an easily explainable cause but may represent serious underlying pathology and can be associated with intolerable symptoms. The classification of ST, consideration of possible etiologies, as well as the decisions of when and how to intervene can be difficult. ST can be classified as secondary to a specific, usually treatable, medical condition (eg, pulmonary embolism, anemia, infection, or hyperthyroidism) or be related to several incompletely defined conditions (eg, inappropriate ST, postural tachycardia syndrome, mast cell disorder, or post-COVID syndrome). While cardiologists and cardiac electrophysiologists often evaluate patients with symptoms associated with persistent or paroxysmal ST, an optimal approach remains uncertain. Due to the many possible conditions associated with ST, and an overlap in medical specialists who see these patients, the inclusion of experts in different fields is essential for a more comprehensive understanding. This article is unique in that it was composed by international experts in Neurology, Psychology, Autonomic Medicine, Allergy and Immunology, Exercise Physiology, Pulmonology and Critical Care Medicine, Endocrinology, Cardiology, and Cardiac Electrophysiology in the hope that it will facilitate a more complete understanding and thereby result in the better care of patients with ST.

Expression of LHCGR (Luteinizing Hormone/Chorionic Gonadotrophin Receptor) in Pheochromocytomas Unveils an Endocrine Mechanism Connecting Pregnancy and Epinephrine Overproduction

BACKGROUND

The mechanisms by which pregnancy may unmask pheochromocytomas and paragangliomas are not totally understood. We hypothesized that gestational hormones may participate in the pathophysiology of catecholamine excess during pregnancy. We report a case of silent pheochromocytoma revealed in a pregnant woman by life-threatening adrenergic myocarditis.

METHODS

In vitro studies were conducted to investigate the effect of estradiol and the pregnancy hormone hCG (human chorionic gonadotropin) on epinephrine secretion by cultured cells derived from the patient's tumor. Expression of LHCG (luteinizing hormone/chorionic gonadotropin) receptor was searched for in the patient's tumor, and a series of 12 additional pheochromocytoma by RT-Q-PCR and immunohistochemistry. LHCGR expression was also analyzed in silico in the pheochromocytomas and paragangliomas cohorts of the Cortico et Médullosurrénale: les Tumeurs Endocrines and The Cancer Genome Atlas databases.

RESULTS

hCG stimulated epinephrine secretion by cultured cells derived from the patient's pheochromocytoma. The patient's tumor expressed the LHCG receptor, which was colocalized with catecholamine-producing enzymes. A similar expression pattern of the LHCG receptor was also observed in 5 out of our series of pheochromocytoma. Moreover, in silico studies revealed that pheochromocytomas and paragangliomas display the highest expression levels of LHCG receptor mRNA among the 32 solid tumor types of The Cancer Genome Atlas cohort.

CONCLUSIONS

Pregnancy may thus favor surges in plasma catecholamine and hypertensive crises through hCG-induced stimulation of epinephrine production by pheochromocytomas.

A unique cardiovascular presentation of pheochromocytoma

We describe a unique presentation of a pheochromocytoma in a normotensive teenager, who presented with symptoms of headache, neck pain, and palpitations. Holter and event monitor tracings revealed intermittent junctional rhythm causing electromechanical dyssynchrony between atrial and ventricular contraction resulting in reported symptoms. Exercise stress testing helped correlate symptomatic junctional rhythm events to episodic hypertension which led to the eventual diagnosis of pheochromocytoma. The exercise test provided insight into the physiologic coupling that the sympathetic and parasympathetic autonomic nervous systems have on the cardiovascular system during exercise and exaggerated hypertension. The patient was found to have MEN2A and partial adrenalectomy resulted in complete resolution of symptoms and arrhythmia. This unusual presentation illustrates the benefit of a comprehensive clinical evaluation, which led to the eventual diagnosis.

Isolated junctional tachycardia in a child after noncardiac surgery: an uncommon clinical presentation

Isolated junctional tachycardia is rare in children but has been reported after cardiac surgery. To date, it has not been reported after noncardiac surgery. This report describes the case of a 3-year-old boy with no cardiac history who experienced transient junctional tachycardia after a right pyeloplasty. Medical therapy was not prescribed initially due to lack of symptoms. However, symptomatic junctional tachycardia recurred, prompting institution of oral beta-blocker therapy. Isolated junctional tachycardia should not be overlooked in the differential diagnosis of pediatric supraventricular tachycardia after noncardiac surgery.