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The diagnostic accuracy of bedside maneuvers in the evaluation of patients with systolic murmurs has not been assessed objectively. Therefore, we evaluated 50 patients with documented systolic murmurs and compared all standard bedside techniques. Murmurs originating within the right-sided chambers of the heart were best differentiated from all other murmurs by augmentation of their intensity with inspiration (100 percent sensitivity, 88 percent specificity) and diminution of their intensity with expiration (100 percent sensitivity, 88 percent specificity). The murmur of hypertrophic cardiomyopathy was distinguished from all other murmurs by an increase in intensity with the Valsalva maneuver (65 percent sensitivity, 96 percent specificity) and during squatting-to-standing action (95 percent sensitivity, 84 percent specificity), and by a decrease in intensity during standing-to-squatting action (95 percent sensitivity, 85 percent specificity), passive leg elevation (85 percent sensitivity, 91 percent specificity), and handgrip (85 percent sensitivity, 75 percent specificity). The murmurs of mitral regurgitation and ventricular septal defect had parallel responses to all maneuvers, but could be differentiated from other systolic murmurs by augmentation of their intensity with handgrip (68 percent sensitivity, 92 percent specificity) and during transient arterial occlusion (78 percent sensitivity, 100 percent specificity), and by a decrease in their intensity during the inhalation of amyl nitrite (80 percent sensitivity, 90 percent specificity). No single maneuver identified the murmur of aortic stenosis, but the diagnosis could be made by exclusion. Although no single maneuver is 100 percent accurate in diagnosing the cause of a systolic murmur, its origin can be determined accurately at the bedside by observation of the response to a combination of maneuvers.
To investigate the relation between changes in left ventricular inflow velocity and the timing of third and fourth heart sounds, simultaneous phonocardiograms and continuous wave Doppler traces were recorded in 48 patients (aged 17-78) with heart disease and in 21 normal children. The onset of the first vibration of the third heart sound coincided with peak left ventricular inflow blood velocity to within 5 ms in all but two of the patients. The mean (SD) difference between the two events was 5 (5) ms, which did not differ significantly from zero. The relation was similar in patients with primary myocardial disease (11), and in those with valve disease (26), hypertension (five), and coronary artery disease (four). In the normal children, the mean interval was 2.5 (5) ms--not significantly different from zero. By contrast, the first deflection of the fourth heart sound consistently preceded the timing of peak atrial inflow velocity by 55 (10) ms. Agreement was much closer between the onset of atrial flow and the onset of the atrial sound (mean difference 1 (5) ms, not significantly different from zero). Gallop sounds seem to be closely related to changes in ventricular inflow velocity, and thus to the effects of forces acting on blood flow. The forces underlying the third sound seem to arise within the ventricle and are responsible for sudden deceleration of flow during rapid ventricular filling. The fourth sound, occurring at the onset of the "a" wave, is more likely to arise from dissipation of forces causing acceleration of blood flow--that is, atrial systole itself.
