Clinical studies on dirofilarial hemoglobinuria: Central venous pressure before and after heartworm removal.

Abstract

Central venous pressure (CVP) was measured before and immediately after surgical heartworm removal from the jugular vein in 22 dogs with dirofilarial hemoglobinuria (caval syndrome). In 19 cases which recovered by sugical removal, CVP was considerably high from 32 mmH2O to 187 mmH2O with a mean of 101.6±35.1(S.D.)mmH2O before heartworm removal. CVP fell in all cases immediately after heartworm removal. The mean CVP after heartworm removal was 61.0±42.9 mmH2O. This level was significantly lower than that before heartworm removal (p<0.001). After heartworm removal, systolic cardiac murmur and jugular pulse improved and hemoglobinemia and hemoglobinuria disappeared. Two of 3 cases, which died after heartworm removal, indicated a high CVP over 200 mmH2O and showed the signs of severe circulatory failure (right heart failure). They also displays terminal signs such as prostration and low body temperature. After heartworm removval, systolic murmur improved passably, but high CVP levels over 175 mmH2Oremained in both cases. Another case did not indicate a high CVP level (66 mmH2O) before heartworm removal. Forty-seven heartworms were removed from this case. However, there was no recovery of the systolic murmur, and CVP fell only 5 mmH2O. In this case, the knotting of a heartworm around the tricuspid chordae was confirmed by autopsy. It was considered that the existence of heartworm mass at the tricuspid valve orifice would be the cause of the high CVP level in this disease. And it was suggested that the tricuspid insufficiency by heartworm mass at the tricuspid valve orifice would be the direct cause of acute circulatory insufficiency that indicates the onset of dirofilarial hemoglobinuria together with many symptoms.