The activation of the contact phase of coagulation by physiologic surfaces in plasma: the effect of large negatively charged liposomal vesicles

The endogenous, negatively charged surface that induces activation of the contact coagulation factors was investigated in plasmas taken from women in late pregnancy and control subjects of child-bearing age. The plasmas from the two groups of subjects were incubated at 4 degrees C for 24 hours either in plastic or in glass tubes and the factor VII coagulant activity (VIIc) was assayed in the treated plasmas. The activation of factor VII under these conditions involves the generation of enzymes derived from factor XII (XIIa). The contact surface is rate- limiting for the activation of factor VII in the plasmas in both groups of subjects and can be supplemented by large multilamellar liposomal vesicles carrying the appropriate density of negative charge. The size of these vesicles is within the range of sizes of the large lipoprotein particles (chylomicrons, very low and intermediate-density lipoproteins). The relationship between the density of negative charge on the liposomal vesicles and VIIc was similar in the late pregnancy and the control plasmas incubated in plastic tubes. At a saturating density of negative charge the observed relative VIIc was similar in both sets of plasmas. The incubation of late pregnancy or control plasma in plastic tubes in the presence of sodium stearate caused VIIc to increase with increasing concentration of the added fatty acid. These results suggest that large lipoprotein particles carrying the appropriate free fatty acid at a sufficient density of negative charge could provide the contact surface that induces the generation of factor XIIa and the subsequent activation of factor VII. Moreover, plasmas from women in late pregnancy have a higher concentration of potential surface and a higher density of negative charge than the plasmas from nonpregnant women.     

Pediatric Intracardiac Thrombus: A Diagnostic and Therapeutic Dilemma

This case highlights the challenges in treating children with intracardiac thrombosis. We describe a teenager who developed an unsuspected de novo intracardiac thrombus. She was treated initially medically and surgically, but required subsequent surgery to treat a life‐threatening recurrence. This case demonstrates an unusual presentation, as well as imaging, diagnostic, and therapeutic dilemmas. More significantly, it emphasizes the importance of a multidisciplinary approach for successful treatment of intracardiac thrombus.     

AngioJet rheolytic thrombectomy in a neonate with pulmonary artery thrombus

A newborn infant with obstructed supracardiac total anomalous pulmonary venous return underwent emergent surgical correction on day of life 0. A surgically placed transthoracic pulmonary artery catheter was used to monitor pulmonary artery pressure and removed on postoperative day 3. Following acute deterioration in respiratory status requiring reintubation, echocardiographic assessment demonstrated findings consistent with pulmonary hypertension and diminished flow to the left lung. Cardiac catheterization confirmed elevated pulmonary artery pressure and near complete occlusion of his left pulmonary artery due to a thrombus. He underwent successful percutaneous catheter‐based thrombectomy using the AngioJet rheolytic catheter, recovered fully, and was discharged home on postoperative day 30. Although thrombotic events resulting in respiratory and hemodynamic compromise are rare in infants, recognition is important and treatment using mechanical thrombectomy can be life saving. © 2013 Wiley Periodicals, Inc.     

Incompatibility of contrast agents with intravascular medications. Work in progress

In vitro and in vivo precipitation of iodinated contrast agents when ioxaglate and papaverine are given together has been reported. To verify these reports and to investigate other medications not previously tested, the authors analyzed mixtures of contrast agents and medications in vitro with a light spectrophotometer and observed them for visible precipitates for up to 120 minutes. Previously reported incompatibilities between ionic or low-osmolality contrast media and medications were verified, and several new incompatibilities were discovered. No incompatibilities were found when the drugs tested were mixed with the new nonionic contrast media.     

Assessing wound severity with color and infrared imaging of reactive hyperemia

This study examined the use of cutaneous reactive hyperemia as a means for noninvasive assessment of wound severity of newly formed temperature-modulated pressure injuries in a porcine model. Two methods to quantify the extent of the reactive hyperemic reflex were developed. First, color image analysis was used to measure the hue of injured tissue. The specific hue of the skin surface of the wounded site was found to provide an indication of the severity of the wounds. Second, infrared imaging, coupled with computer image processing, was used to detect differences in skin temperature. The relative surface temperature of the wounds showed a strong correlation with the presence or absence of deep tissue injury. Both techniques correlated with the severity of the injuries as determined by a histologic assessment of biopsied tissue, but infrared imaging provided the better means to assess wound depth.