The aortic closure sound in pure aortic insufficiency

Area of Science:

• Cardiology
• Cardiovascular Physiology
• Biomedical Engineering

Background:

• The intensity of the second heart sound in aortic insufficiency is debated, with descriptions ranging from accentuated to diminished.
• Extracardiac factors can influence the perceived intensity of heart sounds, necessitating direct intracardiac measurements.

Purpose of the Study:

• To objectively evaluate the intensity of the second heart sound (aortic closure sound) in patients with aortic insufficiency.
• To differentiate the sound's amplitude by eliminating extracardiac influences using intracardiac phonocardiograms.

Main Methods:

• Intracardiac phonocardiograms and pressure measurements were obtained in 28 patients during cardiac catheterization.
• Recordings were taken above the aortic valve and within the left ventricle.
• Data were analyzed from patients with normal aortic valves and those with uncomplicated aortic insufficiency.

Main Results:

• The amplitude of the aortic closure sound was significantly lower in patients with pure aortic insufficiency (1000 +/- 100 dynes/cm2) compared to those with normal aortic valves (3100 +/- 200 dynes/cm2).
• A statistically significant difference (P < 0.001) was observed, confirming reduced sound amplitude in aortic insufficiency.

Conclusions:

• Aortic insufficiency leads to a diminished amplitude of the aortic closure sound.
• This supports the hypothesis that the second heart sound is generated by diastolic vibrations of the aortic cusps.
• Reduced vibrations in aortic insufficiency may stem from impaired valve tensing or diminished driving pressure development during diastole.