Cardiac Arrhythmias at Extreme Altitude

Study Overview
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Brief Summary
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Background: Exposure to high altitudes has been associated with an increased risk of cardiac arrhythmias in healthy subjects and an increased risk of sudden cardiac death. Aim: The aim of the present study is to evaluate the risk and the incidence of cardiac arrhythmias at extreme altitude. Methods: This is a prospective cohort study of healthy volunteers determined to climb Mount Everest. Subjects will be evaluated for eligibility by electrocardiography and echocardiography. All study participants will undergo ambulatory rhythm monitoring in their home environment within 12 weeks of the climb. Subsequently, ambulatory rhythm monitoring will be repeated during the ascent from basecamp to the summit of Mount Everest. The primary endpoint will be the composite of supraventricular and ventricular tachyarrhythmias, and bradyarrhythmias.

Detailed Description
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Background: Several physiological changes at high altitude give rise to a pro-arrhythmic milieu. A fall in atmospheric pressure at high altitude decreases the partial pressure of oxygen (PaO2) and causes arterial hypoxemia. Respiratory alkalosis secondary to hyperventilation causes hypokalemia and hypocalcemia. Both factors facilitate the occurrence of rhythm disturbances, and may be further exacerbated in an adrenergic state with increased epinephrin levels. Objectives: The primary objective is to investigate the incidence of supraventricular and ventricular tachyarrhythmias, and the incidence of bradyarrhythmias in climbers during the ascent of Mount Everest. The secondary objective is to investigate clinical, electrocardiographic and echocardiographic predictors of cardiac arrhythmias at extreme altitude. Methods: This is a prospective cohort study of healthy volunteers climbing Mount Everest. Subjects will be evaluated for eligibility by electrocardiography and echocardiography. All participants will undergo a stress test in order to rule out pre-existing rhythm disturbances during exercise. Study participants will undergo ambulatory rhythm monitoring in their home environment within 12 weeks of the climb. Subsequently, subjects will repeat ambulatory rhythm monitoring during the ascent from basecamp to the summit of Mount Everest. The subjects will act as their own controls.

Official Title
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Risk of Cardiac Arrhythmias at Extreme Altitude

Conditions
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Bradycardia, Arrhythmias, Cardiac, Tachycardia, Ventricular, Tachycardia, Supraventricular

Intervention / Treatment
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* Diagnostic Test: Ambulatory rhythm recording


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥18 years Normal electrocardiogram Normal echocardiography Written informed consent Exclusion Criteria: Known cardiac arrhythmia Evidence of AV-block, left bundle branch block, or repolarization disorders on electrocardiogram Evidence of structural heart disease (valve disease more than mild) or compromised left ventricular ejection fraction as assessed by echocardiography Symptoms or history of skin cancer, rash, skin disease, keloid or injury Cardiac pacemakers, cardiac defibrillators, implantable electrical devices Pregnancy, breastfeeding

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Ambulatory rhythm monitoring<br>Ambulatory rhythm monitoring by use of patch-type device. | Diagnostic Test: Ambulatory rhythm recording<br>* Ambulatory rhythm recording by use of a wearable patch-type device.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of participants detected to have cardiac arrhythmia | Composite of supraventricular and ventricular tachyarrhythmias, and bradyarrhythmias. | The primary endpoint will be assessed during the ascent from basecamp to the summit of Mount Everest and back to basecamp, expected to be on average 5-10 days. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Patterns in the occurrence of cardiac arrhythmias | Occurrence of the composite of supraventricular and ventricular tachyarrhythmias, and bradyarrhythmias. | The outcome will be assessed during the ascent from basecamp to the summit of Mount Everest and back to basecamp, expected to be on average 5-10 days. |