The Doppler guide wire measures phasic flow velocity patterns and linearly tracks changes in flow rate in small, straight coronary arteries. It should facilitate measurement of phasic coronary flow velocity during coronary angiography and angioplasty.

Intradialytic hypotension (IH) is a frequent complication of hemodialysis (HD) and is associated with increased patient mortality and cardiovascular events. We studied IH to determine its variability, correlates, and clinical impact in 13 outpatient HD facilities. Blood pressure was captured by machine download. IH was defined as >30 mmHg decrease in systolic blood pressure to <90 mmHg. Risk factors were assessed by logistic regression and hospitalization by Poisson regression. Time to death and first hospitalization were assessed using Kaplan-Meier analysis in patients completing >20 HD treatments. We studied IH in 44,801 treatments (Tx) in 1137 patients. IH was frequent (17.2% of treatments) and highly variable by patient (0-100% Tx) and dialysis facility (11.1-25.8% Tx). 25.1% of patients had no IH (0% Tx) and 16.2% had IH on >35% Tx. Increased IH frequency was associated with age, female gender, diabetes, Hispanic origin, longer end stage renal disease vintage, higher body mass index, higher ultrafiltration volume, the second and third weekly Tx, lower pre-HD systolic blood pressure, higher difference between prescribed and achieved post-HD weight, and higher dialysate temperature. Dialysis facility was an independent predictor of IH frequency. Patients with >35% IH treatments had poorer survival (P = 0.036), and more frequent and longer hospitalization (P = 0.04, P = 0.002, respectively) than patients without IH. In conclusion, IH frequency was highly variable, associated with individual facilities, patient and treatment characteristics, and correlated with mortality and hospitalization. Identifying practice patterns associated with IH coupled with routine reporting of IH will facilitate medical management and may result in the prevention of IH, decreased mortality, and decreased hospitalization.

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These data demonstrate lack of significant flow improvement beyond most critical stenoses with intra-aortic balloon pumping and the unequivocal restoration and intra-aortic balloon pump-mediated augmentation of both proximal and distal coronary blood flow velocities after amelioration of severe coronary obstructions in patients after successful coronary angioplasty.

Before angioplasty, abnormal coronary flow velocity dynamics are more marked distal than proximal to the stenosis. Greater increase in coronary flow velocities in the distal circulation after relief of endolumen obstruction results in a significant reduction in the proximal/distal flow velocity ratio. Thus, normalization of Doppler-derived flow velocity variables with marked reduction of the proximal/distal flow velocity ratios parallels angiographic success and may prove useful as an additional end point measurement in interventional cases with questionable angiographic findings.