Effect of digoxin and diuretics on high altitude left ventricular dysfunction

Area of Science:

• Cardiology
• Altitude Physiology
• Pharmacology

Background:

• High altitude exposure is known to affect cardiovascular function.
• Understanding the impact on left ventricular function is crucial for acclimatization.
• The role of pharmacological interventions requires further investigation.

Purpose of the Study:

• To investigate the effects of high altitude on systolic time intervals, stroke volume, and cardiac output.
• To evaluate the efficacy of beta-methyldigoxin and a diuretic in mitigating altitude-induced cardiovascular changes.
• To assess left ventricular function during high altitude exposure.

Main Methods:

• Serial estimation of hemodynamic parameters including systolic time intervals, stroke volume, and cardiac output in 51 healthy volunteers.
• Double-blind, placebo-controlled study with three groups: placebo, beta-methyldigoxin, and diuretic.
• Measurements taken at sea level, during 10 days at 3658 m altitude, and upon return to sea level.

Main Results:

• Placebo group exhibited increased heart rate and reduced stroke/cardiac index at high altitude, normalizing upon return.
• Significant deterioration in left ventricular function observed at high altitude, including prolonged pre-ejection period and reduced (dZ/dt)/RZ index.
• Digoxin group maintained normal cardiac indices and myocardial function parameters; diuretic group showed greater deterioration than placebo.

Conclusions:

• High altitude exposure can lead to left ventricular dysfunction and reduced stroke index, potentially causally related.
• Digoxin administration appears to prevent these adverse cardiovascular effects during high altitude exposure.
• Diuretics may exacerbate the negative impact of high altitude on cardiac function.