Contrast-free ultrasound imaging for blood flow assessment of the lower limb in patients with peripheral arterial disease: a feasibility study.

While being a relatively prevalent condition particularly among aging patients, peripheral arterial disease (PAD) of lower extremities commonly goes undetected or misdiagnosed due to its symptoms being nonspecific. Additionally, progression of PAD in the absence of timely intervention can lead to dire consequences. Therefore, development of non-invasive and affordable diagnostic approaches can be highly beneficial in detection and treatment planning for PAD patients. In this study, we present a contrast-free ultrasound-based quantitative blood flow imaging technique for PAD diagnosis. The method involves monitoring the variations of blood flow in the calf muscle in response to thigh-pressure-cuff-induced occlusion. Four quantitative metrics are introduced for analysis of these variations. These metrics include post-occlusion to baseline flow intensity variation (PBFIV), total response region (TRR), Lag0 response region (L0RR), and Lag4 (and more) response region (L4 + RR). We examine the feasibility of this method through an in vivo study consisting of 14 PAD patients with abnormal ankle-brachial index (ABI) and 8 healthy volunteers. Ultrasound data acquired from 13 legs in the patient group and 13 legs in the healthy group are analyzed. Out of the four utilized metrics, three exhibited significantly different distributions between the two groups (p-value < 0.05). More specifically, p-values of 0.0015 for PBFIV, 0.0183 for TRR, and 0.0048 for L0RR were obtained. The results of this feasibility study indicate the diagnostic potential of the proposed method for the detection of PAD.

Venous Thromboembolism Prophylaxis: Need for Continuous Assessment Due to Changes in Risk During the Same Hospitalization.

OBJECTIVE: To explore the role of venous thromboembolism (VTE) risk reassessment in hospitalized medically ill patients without a change in level of care. PATIENTS AND METHODS: In this exploratory retrospective study, the medical records of 171 consecutive adult patients (≥18 years) hospitalized under the medicine service for more than 3 days without a change in the level of care from January 1, 2015, to March 1, 2015, were reviewed. The primary outcome was a change in the risk score between day 1 and day 3 of hospital stay (using the Padua Prediction Score). The secondary outcomes were changes in risk stratification class (low vs high) and cost-benefit analysis. RESULTS: The risk score was significantly different between day 1 and day 3 (4.7±1.7 vs 4.2±1.8; P=.008). All the patients with low risk on day 1 remained at low risk on day 3. However, 25 of 136 patients (18.4%) with high risk on day 1 were reclassified as low risk on day 3 (P<.001). No patients changed from low risk to high risk at day 3. The reclassification could have saved $35 per patient-day of inappropriate pharmacological prophylaxis in addition to patient discomfort, bleeding risk, and heparin-induced thrombocytopenia. CONCLUSION: This is the first study to suggest the need for regular assessment for VTE risk on medicine wards because of changing patient risk. Regular reassessment could reduce health care waste and patient discomfort.

Calciphylaxis: A Disease of Pannicular Thrombosis.

OBJECTIVE: To identify coagulation risk factors in patients with calciphylaxis and the relationship between anticoagulation use and overall survival. PATIENTS AND METHODS: Study subjects were 101 patients with calciphylaxis seen at Mayo Clinic from 1999 to September 2014. Data including thrombophilia profiles were extracted from the medical records of each patient. Survival status was determined using patient registration data and the Social Security Death Index. Survival was estimated using the Kaplan-Meier method, and associations were evaluated using Cox proportional hazards models. RESULTS: Sixty-four of the 101 patients underwent thrombophilia testing. Of these, a complete test panel was performed in 55 and a partial panel in 9. Severe thrombophilias observed in 60% (33 of 55) of the patients included antiphospholipid antibody syndrome protein C, protein S, or antithrombin deficiencies or combined thrombophilias. Of the 55 patients, severe thrombophilia (85%, 23 of 27) was noted in patients who were not on warfarin at the time of testing (27). Nonsevere thrombophilias included heterozygous factor V Leiden (n=2) and plasminogen deficiency (n=1). For the comparison of survival, patients were divided into 3 treatment categories: Warfarin (n=63), other anticoagulants (n=20), and no anticoagulants (n=18). There was no statistically significant survival difference between treatment groups. CONCLUSION: Laboratory testing reveals a strikingly high prevalence of severe thrombophilias in patients with calciphylaxis, underscoring the importance of congenital and acquired thrombotic propensity potentially contributing to the pathogenesis of this disease. These findings may have therapeutic implications; however, to date, survival differences did not vary by therapeutic choice.

Outcomes and total costs of outpatient vs. inpatient peri-procedural anticoagulation management of mechanical prosthetic heart valve patients.

BACKGROUND/OBJECTIVES: The most cost-effective periprocedural management of patients with mechanical heart valves (MHV) is uncertain. The objective was to compare the effectiveness, safety and costs for inpatient intravenous unfractionated heparin (IVUH) vs. outpatient low molecular weight heparin (LMWH) "bridging" as periprocedural anticoagulation management for MHV patients. METHODS: In a case-cohort study, Olmsted County, MN residents with MHV who received outpatient periprocedural LMWH management (cases) over the 11-year period, 1997-2007, were matched to residents with MHV who received inpatient IVUH periprocedural management on valve location and type, and on procedure type. Patients were followed for 3 months following hospitalization to identify thromboembolism (TE) and major bleeding. Total costs from 30 days before to 90 days after the procedure were determined from the Olmsted County Healthcare Expenditure and Utilization Database. Outcomes were compared using survival analysis and costs were compared using the Wilcoxon rank sum. RESULTS: 149 cases (100 aortic, 29 mitral, 20 both; 64% bileaflet) were compared to 149 cohort members (100 aortic, 29 mitral, 20 both; 75% bileaflet). While the 3-month cumulative incidence of TE did not differ significantly among cases (2.7%) and cohort members (4.7%; p = 0.36), major bleeding was significantly lower in cases (5.4% vs. 15.4%; p < 0.005). Total costs were significantly higher for cohort members ($50,984 vs. $39,347; p = 0.002) due to higher inpatient costs ($47,729 vs. $34,860; p = 0.0002). CONCLUSIONS: Outpatient bridging LMWH therapy is equally effective, but safer and less costly than inpatient IVUH as periprocedural anticoagulation management for MHV patients.

Three-month cumulative incidence of thromboembolism and bleeding after periprocedural anticoagulation management of arterial vascular bypass patients.

The objective of this study was to determine 3-month cumulative incidence of peri-procedural thromboembolism (TE) including graft occlusion, and peri-procedural bleeding for chronically anticoagulated vascular bypass graft (BG) patients requiring temporary warfarin interruption for an invasive procedure. Appropriate peri-procedural management of patients receiving chronic warfarin therapy to preserve lower extremity arterial BG patency is unknown. In a protocol driven, cohort study design, all BG patients referred to the Mayo Clinic Thrombophilia Center for peri-procedural anticoagulation (1997-2007) were followed forward in time to estimate the 3-month cumulative incidence of TE and bleeding. Decisions to provide "bridging" low molecular weight heparin (LMWH) were individualized based on estimated risk of TE and bleeding. There were 78 BG patients (69 ± 10 years; 38% women), of whom 73% had a distal autogenous and 53% had prosthetic BG; 45% received antiplatelet therapy. Peri-procedural LMWH was prescribed for 77% of patients and did not vary by BG distal anastomosis location or type. The 3-month cumulative incidence of TE was 5.1% (95% CI 1.4-12.6), including two BG occlusions, one DVT, and one myocardial infarction. Major bleeding occurred in 1 patient (1.28%, 95% CI 0.0-6.94). One patient died due to heart failure. TE and bleeding did not differ by bridging status. The 3-month cumulative incidence of TE among BG patients in whom warfarin is temporarily interrupted for an invasive procedure may be higher than in other "bridging" populations (atrial fibrillation, prosthetic heart valve, venous thromboembolism). This finding underscores the often tenuous nature of distal bypass grafts necessitating an aggressive approach to peri-procedural anticoagulation management.