Abstract
Decreased cardiac output (CO) and systemic oxygen transport (SOT) in polycythemia (P) are attributed to increased blood viscosity and regarded as potentially harmful. Since P is common in cyanotic heart disease, we studied its effects on CO, SOT and left ventricular coronary blood flow (CBF) and oxygen transport (LVOT) in dogs with acute isovolumlc P. Hematocrit increase to 65-70% caused falls in CO and SOT; despite P, CO rose with hypoxemia or adenosine infusion. P markedly decreased CBF and cardiac work; slightly decreased LVOT, myocardial oxygen consumption and coronary sinus oxygen saturation; and increased coronary vascular resistance(Rc). Cardiac stress (pacing, aortic stenosis, arteriovenous fistula), hypoxemia and adenosine infusion lowered Rc. Changes in LVOT were more closely related to changes in pressure work and myocardial oxygen consumption than to hematocrit. With maximal coronary vasodilatation, Rc doubled when hematocrit rose from 45% to 65%. Our results Indicate that autoregulation is more important than viscosity in regulating CO, CBF, SOT and LVOT in P. With maximal coronary vasodilatation, however, increased blood viscosity in P reduces LVOT and suggests that with maximal stress there could be ischemlc myocardial damage.
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Hoffman, J., Surjadhana, A., Boerboom, L. et al. POLYCYTHEMIA, CARDIAC OUTPUT AND CORONARY BLOOD FLOW. Pediatr Res 11, 392 (1977). https://doi.org/10.1203/00006450-197704000-00140
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DOI: https://doi.org/10.1203/00006450-197704000-00140