First heart sound in atrial septal defect

Area of Science:

• Cardiology
• Physiology

Background:

• Atrial septal defect (ASD) is a common congenital heart condition.
• The exact mechanism of the first heart sound, particularly its components, is not fully elucidated.
• Understanding the first heart sound's components can aid in diagnosing and managing cardiac conditions.

Purpose of the Study:

• To investigate the characteristics of the first heart sound in patients with secundum-type atrial septal defect (ASD).
• To compare phonocardiograms and carotid pulses of ASD patients with healthy controls.
• To determine the contribution of tricuspid valve function versus aortic events to the second component (Ib) of the first heart sound.

Main Methods:

• Retrospective study of 25 patients with secundum-type ASD and 25 age-matched healthy controls.
• Phonocardiograms and carotid pulses were recorded and analyzed.
• Key parameters analyzed included intervals between first heart sound components (Ia and Ib), their amplitudes, and the relationship between carotid upstroke and the first heart sound.

Main Results:

• No significant differences were found in the intervals between the first heart sound components (Ia and Ib) between ASD patients and controls.
• No increase in the amplitude of the Ib component was observed in ASD patients.
• A slight precedence of aortic valve opening over the Ib component was noted in both groups, suggesting a link to aortic events.

Conclusions:

• The findings suggest that the second component (Ib) of the first heart sound is unlikely to be primarily influenced by tricuspid valve function in ASD.
• The Ib component appears closely related to dynamic events following aortic valve opening, such as blood acceleration and deceleration in the aortic root.
• These results contribute to a better understanding of the phonocardiographic characteristics of ASD and the physiological basis of the first heart sound.