Value Of Blood Volume Analysis In Patients With Left Ventricular Assist Devices.

Abstract

Introduction Implantable left ventricular assist devices (LVAD) have dramatically changed the face of mechanical circulatory support of patients with advanced heart failure. With increased durability, reliability and safety these devices have extended the horizon of functional improvement, life quality and survival. Beyond crucial pre-operative and intra-operative issues, several device-host interface issues are important for successful outcomes. Among these are clear understanding of intravascular volume status, red blood cell volume status. Blood volume analysis (BVA) is a blood test that measures these 3 metrics using the indicator dilution technique, with rapid personalized and actionable results. We used BVA to evaluate 10 consecutive stable ambulatory patients supported with LVAD. Results The patients were seven men and three woman aged 32-70 years. Duration of LVAD support at the time of outpatient BVA (Daxor, Oak Ridge, TN) ranged from 46-1460 days. Two out of eight patients had LVAD (HM3(5), HW(4), HM2(1)implanted as bridge to transplant, all others as destination therapy. Eight out of ten patients were obese with deviations from normal body weight of 22-117% and average BMI of 32.6. All patients were felt to be improved and stable compared to pre-LVAD (INTERMACS 1-3) and none had evidence of device malfunction or drive line infection. All patients had variations in total blood volumes, plasma volume and red cell volume (Table1). Only two out of ten patients had all three BVA parameters within normal limits. Half of the patients had significant hypervolemia, which was not suspected on physical exam. Two out of ten patients had significant hypervolemia with polycythemia, which was not clinically suspected. Conclusions In summary, BVA and its individualized, unique metrics is a valuable test when used in patients with LVAD's. Despite improved functional status and adequate device performance wide variations are still present in patients being supported with LVAD's. Additionally, measurement of red blood cell volume is helpful in determined variations (anemia or polycythemia) that might not be noted clinically and might presage future hemolytic and/or thrombotic events despite adequate anticoagulation. Implantable left ventricular assist devices (LVAD) have dramatically changed the face of mechanical circulatory support of patients with advanced heart failure. With increased durability, reliability and safety these devices have extended the horizon of functional improvement, life quality and survival. Beyond crucial pre-operative and intra-operative issues, several device-host interface issues are important for successful outcomes. Among these are clear understanding of intravascular volume status, red blood cell volume status. Blood volume analysis (BVA) is a blood test that measures these 3 metrics using the indicator dilution technique, with rapid personalized and actionable results. We used BVA to evaluate 10 consecutive stable ambulatory patients supported with LVAD. The patients were seven men and three woman aged 32-70 years. Duration of LVAD support at the time of outpatient BVA (Daxor, Oak Ridge, TN) ranged from 46-1460 days. Two out of eight patients had LVAD (HM3(5), HW(4), HM2(1)implanted as bridge to transplant, all others as destination therapy. Eight out of ten patients were obese with deviations from normal body weight of 22-117% and average BMI of 32.6. All patients were felt to be improved and stable compared to pre-LVAD (INTERMACS 1-3) and none had evidence of device malfunction or drive line infection. All patients had variations in total blood volumes, plasma volume and red cell volume (Table1). Only two out of ten patients had all three BVA parameters within normal limits. Half of the patients had significant hypervolemia, which was not suspected on physical exam. Two out of ten patients had significant hypervolemia with polycythemia, which was not clinically suspected. In summary, BVA and its individualized, unique metrics is a valuable test when used in patients with LVAD's. Despite improved functional status and adequate device performance wide variations are still present in patients being supported with LVAD's. Additionally, measurement of red blood cell volume is helpful in determined variations (anemia or polycythemia) that might not be noted clinically and might presage future hemolytic and/or thrombotic events despite adequate anticoagulation.