Case Studies In Small Animal

Cardiovascular Medicine

Case 1

Right ventricular pressure waveforms

pressurereduced.gif (5759 bytes)

The scale is on the left in mm of Hg (0 to 20). Consequently, each horizontal line represents 4 mm Hg. The end-diastolic pressure is increased to approximately 9 mmHg (normal is < 5 mm Hg). The early diastolic pressure does not reach zero mmHg as it should in a normal dog but only decreases to approximately 6 mmHg. It then increases rapidly and plateaus, making it look like the square root symbol ("square root sign"). One liter of normal saline was infused rapidly into a peripheral vein. Following this, the diastolic pressure increased another 5 mm Hg so that the end-diastolic pressure was 14 mm Hg. The diastolic pressure should not increase appreciably in a normal dog of this size with this amount of a fluid challenge. Systolic right ventricular pressure is normal.

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