The ball-and-cage aortic prosthesis consists of a silastic ball, which has a specific gravity of 1 1499 (S.G. of blood=1 050), enclosed within a metal cage (Starr and Edwards, 1961). The sounds produced by the ball during its movement about the cage are very characteristic and easily recognized, because they are of high frequency, short duration, and great amplitude. We have studied the phonocardiogram in patients whose aortic valves were replaced by ball-and-cage prostheses, in order to elucidate the mechanisms of these sounds, and to obtain information from them about the phases of the cardiac cycle. SUBJECTS AND METHODSThe subjects of this study were 40 patients whose aortic valves had been replaced, 34 with a Starr-Edwards prosthesis and 6 with a Magovem prosthesis. Every patient had at least two phonocardiograms: one before and one after operation. Some had several post-operative phonocardiograms as part of their clinical assessment and whenever their clinical or auscultatory findings changed. The recordings were made by a piezoelectric crystal microphone on a photographic recorder (New Electronic Products, Ltd.). Recordings were made using the high, medium, and low frequency bands. The electrocardiogram was used as a reference trace, and all recordings were made at a paper speed of 80 mm. pqr sec.The phonocardiograms were analysed with the aid of a pair of callipers and a hand lens and measurements were made to the nearest 5 msec.The following measurements were made. (1) Onset of QRS to first heart sound (electrical-mechanical interval). These measurements were corrected for heart rate byReceived August 18, 1966. 446 dividing them by the square root of the R-R interval (Bazett, 1920). In 15 patients, the phonocardiograms were recorded simultaneously with central aortic and pulmonary artery pressures. These were obtained through nylon tubing inserted percutaneously (Seldinger, 1953) by means of strain gauges (Statham G 23/D.B.), and the whole system had a resonant frequency of 34 c.p.s., with a uniform response up to 12 c.p.s. The delay in transmission of pressures was determined by a simple experiment (Raftery, 1965) and found to be 10 msec. This figure was subtracted from all pressure wave timings.The behaviour of the valve in a pulse duplicator was studied by means of a hydraulic system consisting of a Starr-Edwards aortic valve mounted in Perspex tubing of uniform diameter. A pulse duplicator (McMillan, 1955) was used to produce intermittent flow across the valve, simulating the heart beat. The movement of the ball was recorded on cine-film at 100 frames a second. During the film exposure, the rate of pulsation, the simulated ventricular pressure, and the peripheral resistance were varied, and the effects ofthese manceuvres on the movement of the ball were observed. RESULTSSystolic Sounds. The most striking feature of the phonocardiogram was the presence of a variable number of sounds associated with the beginning of the ejection period. In every case in this series there was at least one sound of v...
Twenty-six patients with constrictive pericarditis have been investigated and treated-by surgical in addition to medical methods in 22, and by medical management alone in four. A tuberculous aetiology was proved in only two patients but was probable in 10 others. One patient developed constriction of the heart following a stab wound, which caused a haemopericardium, and one after organization of a pericardial cyst. In the remainder no cause was found. The clinical features and diagnostic criteria are described, with emphasis on cardiac catheterization and angiocardiography. Operative results are given: two patients died after the operation, and the results are compared with other series. All surviving patients were improved: greatly in 13 and moderately in three. Four patients had a poor result due to long-standing myocardial disorder, and so we stress the importance of early operation, with reference to illustrative cases. Conversely, the practicability of treating certain patients by medical means alone is demonstrated. The criteria for operation are discussed with reference to repeated cardiac catheterization and angiocardiography.
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