An in vitro flow visualization study has been carried out on a range of aortic and mitral valve prostheses mounted in rigid, transparent models of the aorta and left ventricle. The valves were subjected to pulsatile flow and the flow patterns produced by each valve were visualized by injecting multi-dye streams into the valve orifice, or by observing illuminated particles suspended in the flow. The patterns were recorded by still photography and high speed cinematography.In the mitral region each tilting disc valve produced a large vortex which dominated the ventricular cavity. By contrast disc and ball valves each produced an annular vortex, and the bioprosthesis produced a central flow.In the aortic region the flow patterns produced by a tilting disc valve depended on the orientation of the valve in the aorta. The aortic ball valve was found to produce less flow disturbance than either tilting disc valve or the porcine bioprosthesis.

Murmurs are turbulent sounds from blood flowing through the heart due to a physiological abnormality. The term murmur indicates an abnormal heart sound, and not a term describing a medical diagnosis. Auscultating a murmur is a vital assessment audible by even an inexpensive stethoscope. Identifying a murmur is an important nursing assessment of flow of blood, just as rales are important in recognizing fluid in the lungs, or tinkling bowel sounds alerting us to an ileus. Murmur identification matters for early identification of valvular heart disease and ultimately patient outcomes. This brief article shares study findings of a skill deficit in cardiac auscultation in nursing, patient populations at risk for heart murmurs, complications stemming from VHD, and proposed remedies for the skill deficit.

Wright, J. T. M. (1977). Thorax, 32,[296][297][298][299][300][301][302]. An in-vitro assessment of the hydraulic characteristics of the Mark II Abrams-Lucas mitral valve prosthesis. As a result of the durability problems associated with the first Abrams-Lucas mitral valve, a redesigned model has recently been introduced into limited clinical trials. The new valve was subjected to in-vitro pulsatile flow studies, and measurements were made of mean diastolic pressure gradient and volume of reflux on closure. Similar measurements were made on other mitral valve prostheses of comparable size. High-speed cinematography was used to analyse the motion of the occluder during the simulated cardiac cycle, and the flow patterns produced by the valve in the model ventricular cavity were observed and photographed.The pressure gradient of the Abrams-Lucas valve was significantly lower than that of the 29 mm Bj6rk-Shiley valve and all other prostheses tested, but its reflux level was higher at 12 ml per stroke. The valve opened and closed smoothly and the flow visualisation study revealed that the valve produced a large vortex or swirl in the model ventricular cavity.The first Abrams-Lucas mitral valve prosthesis underwent limited clinical trials a decade ago (Abrams, 1968) and proved to be haemodynamically satisfactory as a mitral valve replacement.The limited experience gained from the 40 or so surviving patients indicated that the incidence of thromboembolic complication associated with the prosthesis was appreciably less than that associated with the Starr-Edwards model 6120 silicone .A. rubber ball valve which was inserted into a similar group of patients at the same centre (Abrams, 1976). However, the durability of the prosthesis was found to be inadequate because there was significant wear of the hooks which retained the flap to the orifice. This wear limited the useful life of the valve to five to seven years. Figure 1 shows

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This has been evolved with a modified pulse duplicator and the use of a hot film probe for measuring velocity, direction, and turbulence. Many of the commercially available mitral valve prostheses are being investigated for their flow characteristics. In addition, efficiency is being examined and some unusual findings point to the possibility of a hydraulic ram effect in the normal mitral valve that allows opening to commence before the end of ventricular systole.TRIAL OF A NEW ANTI-MYXOVIRUS COMPOUND J. E. STARK Two hundred and sixty-four male students living in a hall of residence volunteered to take part in the trial and were randomly allocated into two groups. One group received a synthetic isoquinoline derivative (UK. 2371) daily in divided doses and the other group received identical placebo tablets.During the five weeks of the trial tablets were distributed daily and volunteers were asked to return any tablets which had not been taken. As an additional guide to tablet acceptance a small quantity of isoniazid was incorporated into some active and placebo tablets and urine samples collected at appropriate times were tested for isoniazid derivatives.Volunteers were questioned each week about their health and were asked to report all respiratory and other illnesses. All respiratory illnesses were fully investigated for virus and mycoplasma infections. Full toxicity studies were carried out.The preliminary findings are reported with particular reference to (1) protection against acute respiratory illness provided by the drug; (2) assessment of the novel isoniazid marker system; and (3) the factors affecting acceptance of medication by volunteers.MYCOPLASMA PNEUMONIAE M. C. JONES A retrospective study was made of 100 cases of infection with Mycoplav.n nneumoniae notified through the Public Health Laboratory four-weekly review during 1967-68, and diagnosed by isolation or complement fixation studies. The mode of presentation, physical, radiological and haematological findings, complications, treatment, and progress are reported.The results are also presented of an investigation into the isolation rate of Mycoplasma species (including pneumoniae, hominis, orale, and salivarium) from the nasopharynx of patients admitted to hospital with acute exacerbations of asthma, bronchitis or bronchiectasis and from the nasopharynx and bronchial tree of patients submitted to bronchoscopy. We measured the heat debt incurred during thoracotomy, first with no particular measures taken to prevent heat loss and, secondly, using a heat-reflecting aluminium foil blanket wrapped around the lower half of the patient.Our method of measuring heat loss was adapted from that of Burton and Benzinger. Deep body, calf, forearm, and abdominal skin temperatures were measured. From these readings the average body temperature and the change in heat content were calculated.Our results are of interest for several reasons: 1. The average heat debt without precautions against heat loss was 20 Kals per hour. This involves a doubling of the metabolic ...