A 40-year-old patient admitted to an intensive care unit with position-dependent palpitations reaching 240 beats per minute was found to have a 7 × 7 cm extracardiac mediastinal mass compressing cardiac structures, highlighting rare mechanical causes of emergency room rhythm disorders.
Palpitations are one of the most common symptoms among patients visiting the emergency department, with causes ranging from benign to life-threatening. They are characterized by the sensation of irregular, rapid, or forceful heartbeats in the chest or a pounding sensation in the neck. Extracardiac mediastinal masses, although rare, may present with palpitations and cardiac dysrhythmias through various pathophysiological mechanisms.
Case Presentation: Position-Dependent Tachycardia and Clinical Findings
When the Heart Pays for the Chest
A 40-year-old man was admitted to our intensive care unit for palpitations occuring at change of position. The episodes were triggered when assuming the sitting or lateral decubitus positions, and relieved when moving into the supine position. He had a past medical history of a primary mediastinal hepatoid adenocarcinoma, initially revealed by an episode of hemoptysis with pleural effusion, and confirmed by histopathological examination. He received a total of three cycles of chemotherapy. Seven months after completing his last chemotherapy cycle, he presented with position-dependent palpitations, leading to his current admission.
Clinical examination revealed a conscious, hemodynamically stable patient with a heart rate of 240 beats per minute and a blood pressure of 110/70 mmHg. By changing to a supine position, the patient’s heart rate slowed down, with a heart rate reaching 86 bpm. Resting electrocardiogram showed a regular narrow-complex sinus tachycardia with a heart rate reaching 240 bpm. P waves are discernible before each QRS complex, with a 1:1 atrioventricular relationship and a normal P-wave axis (+62°). The PR interval is 72 ms, and the QRS complexes are narrow (76 ms). Upon further investigation and initial treatment with an oral beta-blocker, the patient had an enormous anterior and middle mediastinal mass extending vertically across all three anatomical levels, with significant mass effect on cardiac structures explaining his dysrhythmia occurring at the change of position. Given the size of the mass and its close relationship to surrounding structures, the patient was started on chemotherapy while continuing beta-blocker therapy.
Pathophysiological Mechanisms of Extracardiac Mass Compression
The Rhythms of the Moon
Beyond direct myocardial irritation or infiltration, these masses may induce arrhythmias through mechanical compression of cardiac structures, particularly the atria, resulting in local myocardial stretch and alterations in electrophysiological properties through mechano-electrical feedback. Compression of adjacent neural pathways or coronary vessels may also contribute to cardiac dysrhythmias. Depending on the histological type, size, and anatomical relationships of the mass, management may require surgical excision, chemotherapy, or radiotherapy, with treatment directed at relieving the underlying mechanical or pathological cause. Palpitations are most often a symptom of a benign underlying condition; however, they can also be a sign of potentially serious and life-threatening diseases, and hence a thorough investigation is important.
Broader Emergency Room Context and Lunar Phase Analysis
Diagnosing paroxysmal cardiac arrhythmias early poses a challenge, yet it holds paramount significance. Certain patients hold strong beliefs regarding the moon’s impact on cardiac arrhythmias. This study aims to examine the potential correlation. In our emergency room, each patient presentation is assigned an admission diagnosis.
An analysis was conducted on admission diagnoses from 2012–2020 (before the coronavirus disease 2019 pandemic). The frequency of rhythmological diagnoses was investigated, both collectively and separately, as well as categorized by the underlying pathomechanism, in relation to the lunar phase and the moon’s proximity to the Earth at the time of admission. Moreover, the impacts of sex, age, and weight were evaluated.
A total of 58,230 patient presentations were recorded, with 16.9% coded with rhythmological diagnoses. No significant differences were found in the distribution of cardiac arrhythmias concerning lunar phases or the moon–Earth distance. Sex, age, and weight did not influence this distribution, except in a small group of underweight patients (<55 kg), where a statistically significant difference was observed with greater moon distance. To verify this result, we investigated all existing Holter records of underweight patients presenting to the emergency room between 2017 and 2020. In 195 24-h Holter recordings, a uniform burden of supraventricular extrasystoles and atrial fibrillation/flutter irrespective of the moon’s distance from the Earth was observed. Contrary to patients’ beliefs, the moon does not seem to affect the presentations with rhythmological complaints and diagnoses in our single-center analysis, irrespective of age, sex, or the arrhythmia type. The moon cannot aid in diagnosing paroxysmal arrhythmias.
