| Popis: |
T HE "millwheel" murmur heard in pulmonary air embolism is due to the turbulent flow of blood mixed with air in the beating right ventricle. 1,4,'~ It has been induced experimentally with the intravenous injection of small amounts of air, 3 and it has been found that the nature of heart sounds changes as the quantity of air injected increases. 7 Shivpuri and coworkers 6 have shown experimentally that characteristic heart sounds precede the onset of the "millwheel" murmur. When air was introduced continuously by way of the femoral vein at the rate of 0.5 cc per sec in dogs in the supine position, after 10 to 15 sec the heart sounds became metallic and resonant in character and the heart rate increased. After 20 to 25 sec, with continued injection at 0.5 cc per sec, the sounds became drum-like. This characteristic metallic sound has been called the "drum sign" and has been considered pathognomonic of venous air embolism. The sound soon became rhythmic and louder, resembling the galloping of a horse on a wooden bridge. At 30 to 40 sec a systolic churning murmur, the "millwheel" murmur, first appeared. It completely replaced the precordial heart sounds at 50 to 60 sec. Thus, the "drum sign" may occur prior to the "millwheel" murmur. On the other hand, Durant, et al., in their experiments 1,2 found that the "millwheel" murmur was heard immediately after injection of air, coincident with air reaching the right side of the heart as demostrated by angiocardiographic studies. This sound followed the injection of air into the femoral vein of dogs in both the supine and the left lateral position as a bolus of 5.0 to 7.5 cc of air per kilogram of body weight, considerably more than the initial amounts injected in the experiments eliciting the "drum sign." The following case presented characteristic features of the "drum sign" observed in animals, and may help to correlate the work of Shivpuri and Durant. |
