| dc.description.abstract | demonstrated on a phonocardiogram when atrial systole
occurs in the middle of ventricular systole in complete
heart block.3 Under these circumstances the atrioventricular
valves are closed and ventricular filling is
obviously impossible. A presystolic gallop in an
abnormal heart does not therefore, as stated in your
annotation, result from the increased intensity of the
low-pitched vibrations seen on a phonocardiogram of
normal subjects, but is due to a different vibration which
moves away from the first sound into a presystolic
position.3-8
Finally, you have referred to the third heart sound
gallop which " may be heard in heart failure, in mitral
incompetence, or in constrictive pericarditis."
Admittedly the diastolic sound in these instances may
result from the same basic mechanism (in this respect
the recent work of Nixon,9 who disputes the common
belief that a third heart sound is produced by a vibration
of the ventricular muscle, is noteworthy), but, since the
sound associated with constrictive pericarditis usually
occurs earlier and is higher pitched10 than a third heart
sound gallop, should it not be regarded separately
and be referred to as the early diastolic sound of
constriction ?-I am, etc., | en |
