| transmural pressure | Pressure across the wall of a cardiac chamber or of a blood vessel. In the heart, transmural pressure is the resultant of the intracavitary pressure minus the extracavitary (i.e., pericardial) pressure and is the distending, i.e., true filling, pressure of the cardiac chamber of measurement when this is done during diastole. Since the pericardial pressure normally approximates zero, the filling pressure (usually equal to ventricular diastolic mean pressure), obviating the complexities of measuring pericardial pressure. (05 Mar 2000) |
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| transmutation | <radiobiology> Transformation of atoms of one element into atoms of another element via nuclear reactions. (for example, the transmutation of uranium-238 into plutonium-239 via the absorption of a neutron and subsequent beta emission.) (09 Oct 1997) |