Late systolic murmurs, particularly those which are preceded by a mid systolic click (42, 49) were since long considered of extra cardiac origin (40, 43), even when accompanied by a thrill (21).We now know that they can be caused by mitral incompetence of different origin (3, 4, 41, 64, 79) and may occur in cases with systolic bulging of the mitral valve (5, 13, 32, 33, 34, 35a, 46, 48, 70, 71, 72, 80).The problem arises whether we can differentiate by phonocardiographic criteria between extracardiac (31) versus intracardiac (3, 4, 62) late systolic murmurs, combined or not with mid or late systolic clicks. The second question is whether we can diagnose the presence or absence respectively of bulging, valvular mitral incompetence or papillary muscle dysfunction (10, 12, 29, 57) in the syndromes going with a late systolic murmur.Several phonocardiographic features have been put forward, which lend support for the extracardiac origin of late systolic murmurs, while other characteristics are known to favor an intracardiac nature.It is our opinion that none of these features single or even in combination, is reliable in separating the above mentioned syndromes. On the contrary: as a result of intracardiac phonocardiographic studies several "classical" phonocardiographic qualities of systolic and late systolic murmurs and clicks such as regularity or vibratory character of the murmur (11, 89), respiration dependent configuration (35, 42, 53, 62), timing (35), frequency (89), have been proven to be unreliable and even fault. A precise re-evaluation of phonocardiographic data and characteristics in these new syndromes possibly can warrant their value in clinical diagnosis in the future.
MethodsThe phonocardiograms were made by means of photographic recording of the deflections of four mirror-galvanometers. The "Hellige"-apparatus (T 9900/4) contains the four filters of MAASZ and WEBER (51).These are called respectively 35, 70, 140 and 250 cps filters according to the criterion of the "rated frequency". The slopes, determined by the tangent to the 10% point, are respectively 12, 20, 24 and 28 dB per octave.The piezo electric chestwall microphone was used, of which some characteristics, especially the dependence on the mechanical impedance of the chcstwall, were recently published (87a). The transmission of the sound vibrations is direct, the diameter of the area of contact amounts to 15 ram. During the recording the microphone rests on the several locations with its own weight, which amounts to 0.8 kg.The pulsation records are registered with the aid of a crystal pickup, connected to a tambour; the time constant is at least 1.5 second.The apex cardiogram is the conventional one: it records the displacement in an intercostal site in relation to the surrounding chest wall.
