Effects of digitalis on normal and abnormal left ventricular segmental dynamics.

Area of Science:

• Cardiology
• Cardiovascular Physiology

Background:

• Coronary artery disease (CAD) often leads to regional left ventricular (LV) dysfunction.
• Understanding how positive inotropic agents affect regional LV performance in CAD is crucial.

Purpose of the Study:

• To investigate the effects of digoxin on regional left ventricular (LV) performance in patients with stable coronary disease.
• To assess whether digoxin improves or exacerbates segmental LV abnormalities.

Main Methods:

• Nine patients with stable coronary disease underwent continuous ventricular dynamics assessment.
• Computer-assisted analysis of fluoroscopic motion of surgically implanted myocardial markers was used to define LV segments.
• Measurements included mean velocity of circumferential fiber shortening and ejection fraction before and after digoxin administration.

Main Results:

• Digoxin significantly increased mean velocity of circumferential fiber shortening (19%) and ejection fraction (4.5%) in patients with coronary disease.
• While 83-91% of normal LV segments improved, only 45-55% of initially abnormal segments showed benefit.
• Segmental dyssynergy increased in some areas, even with enhanced overall ventricular function.

Conclusions:

• Digoxin enhances overall left ventricular (LV) performance in patients with coronary disease.
• However, digoxin may deteriorate performance in abnormal LV regions due to increased afterload and improved dynamics in normal areas.
• These findings highlight potential risks of digoxin in patients with heterogeneous LV dysfunction from coronary artery disease.