Abstract
Chuvash polycythemia is characterized by a homozygous 598C>T mutation in VHL and up regulation of HIF-1α during normoxia. Disorders of chronic hypoxia may be complicated by the development of pulmonary hypertension. Because of the up regulation of the hypoxic response in Chuvash polycythemia, we postulated that there may be a tendency to increased pulmonary artery pressures in this condition as well. To test this hypothesis, we analyzed results for Doppler echocardiography in 15 patients with Chuvash polycythemia and 15 Chuvash individuals without polycythemia. The tricuspid regurgitation velocity (TRV) allows estimation of pulmonary artery systolic pressure. A TRV of 2.5 m/sec or higher corresponds to a pulmonary artery systolic pressure of at least 35 mm Hg (normal up to 32 mm Hg), while a TRV of 3.0 m/sec or higher to a pressure of at least 46 mm Hg. The results are summarized in the Table.
Pulmonary artery pressures as estimated by tricuspid regurgitation velocity (TRV) in Chuvash subjects with and without polycythemia
Chuvash polycythemia (n = 15) Controls (n = 15) P Age in years; mean (SD) 35 (17) 35 (17) 1.0 Female sex in no. (%) 8 (53%) 8 (53%) 1.0 Hemoglobin in g/dL; mean (SD) 16.7 (2.3) 13.3 (1.2) <0.001 TRV in m/sec; mean (SD) 2.2 (0.6) 1.4 (0.6) 0.001 TRV > 2.4 m/sec in no. (%) 4 (27%) 0 (0%) 0.1
Most of the patients with Chuvash polycythemia were receiving phlebotomy therapy and therefore many had hemoglobin concentrations in the upper normal range. Four of the patients with Chuvash polycythemia and none of the others had TRV ≥ 2.5 m/sec (range of 2.5 to 3.0), and mean TRVs were significantly higher in the patients with Chuvash polycythemia. Interestingly, the mean ± SD TRV in these 15 patients with Chuvash polycythemia was identical to the mean ± SD TRV that was recently reported in 195 American patients with sickle cell disease (Gladwin et al, NEJM2004;350:886), another hematological condition with a tendency to pulmonary hypertension. While the pulmonary arterial pressures detected so far in Chuvash polycythemia patients are lower than those in patients with primary pulmonary hypertension, our results suggest that pulmonary hypertension may be an unrecognized complication of Chuvash polycythemia.
Pulmonary artery pulse pressure and wave reflection in chronic pulmonary thromboembolism and primary pulmonary hypertension
