The objective of this study was to determine the constraining effect of the normal human pericardium. Accordingly, immediately after thoracotomy in nine patients undergoing elective cardiac surgery, we measured mean pericardial surface pressure over the lateral free wall of the left ventricle with a flat balloon as well as mean right atrial pressure while incrementally infusing up ALTHOUGH it is well recognized that the diseased pericardium may cause a significant impairment to ventricular filling, the effect of the normal pericardium on the diastolic properties of the ventricles remains controversial. Based on measurements obtained with fluid-filled catheters, there has been a general consensus that pericardial pressure is equal to intrathoracic pressure,. 2 and is thus of little hemodynamic significance. However, Holt et al. ,3 using a flat liquid-containing balloon, demonstrated that the magnitude of pericardial pressure was substantial and similar to right atrial pressure.To Patients and methods Nine patients (mean age 54 years) scheduled for elective cardiac surgery gave informed consent to participate in this investigation; the protocol was previously reviewed and approved by the institutional ethics committee on human research.

No abstract

No abstract

The effects of ultrasound on the mechanical properties of isometrically contracting rat papillary muscle have been studied as a function of the intensity of the ultrasonic irradiation. Each muscle was subjected to irradiation at 1.1., 2.2, and 3.3 W/cm2 at a frequency of 2.3 MHz. Ultrasonic irradiation caused heating in the vicinity of the muscle; thus it was necessary to separate the pure thermal and ultrasonic effects. After irradiation the bath temperature was increased so that the muscle reached the same temperature which occurred during ultrasonic irradiation. The mechanical parameters measured during the equivalent thermal procedure were compared with the parameters during irradiation. There was a significant (p less than 0.05) decrease in resting force which was significantly different from the equivalent thermal intervention and could be related to the ultrasonic intensity. Thus, the effect of ultrasound on rat papillary consists of two components, a thermal component which affects all parameters studied and a nonthermal component which affects only the diastolic force.

No abstract