Direct Recording of Sounds and Pressures within the Heart.

Pressure waves and vibrations in the heart and great vessels may be conducted to a manometer outside the body by a system of tubing filled with fluid. More than a metre of tubing is usually needed as the circulation is entered at an arm vein. Any such system has the following defects. 1. Delay in the transmission of the low frequency pressure waves to the manometer: the delay will vary slightly with different tubes and with the temperature and density of the fluid within. 2. Unwanted vibrations set up along the length of the tubing as its sides are set in motion by the heart chambersthat it traverses. 3. Smoothing-out of the pressure waves or overshoot is almost unavoidable as a result of the elasticity of the tubing and the inertia of the fluid. 4. The high frequency, low amplitude vibrations that constitute audible sounds and murmurs are so poorly conducted that no satisfactory sound record can be made. Elimination of the long fluid column by the. use of a miniature manometer introduced into the heart may overcome all these difficulties. Such a manometer is now available and Soulie and his team have reported their extensive use of the Allard-Laurens micromanometer (Soulie et al., 1961). The present paper reports our preliminary experience with this instrument.