Temporary intravascular shunts for peripheral vascular trauma.

Polyvinylchloride (PVC) disposable endotracheal suction catheters were successfully used as temporary intravascular shunts in 5 patients of popliteal artery trauma. These simple shunts should be used routinely in such conditions to immediately re-establish blood supply to the ischaemic limb particularly in patients of polytrauma where systemic anticoagulation is contraindicated. This avoids the inherent delay prior to vascular repair and reduces the incidence of irreversible ischemia

Temporary intravascular shunts for peripheral vascular trauma

Polyvinylchloride (PVC) disposable endotracheal suction catheters were successfully used as temporary intravascular shunts in 5 patients of popliteal artery trauma. These simple shunts should be used routinely in such conditions to immediately re-establish blood supply to the ischaemic limb particularly in patients of polytrauma where systemic anticoagulation is contraindicated. This avoids the inherent delay prior to vascular repair and reduces the incidence of irreversible ischemia

Spironolactone prevents the inducibility of ventricular tachyarrhythmia in rats with aldosteronism

Myocardial fibrosis is considered a substrate for fatal ventricular arrhythmias (VAs). In rats receiving aldosterone/salt treatment (ALDOST) for ≥4 weeks, foci of myocardial scarring that replace necrotic cardiomyocytes appear scattered throughout the right and left sides of the heart. We hypothesized that this adverse structural remodeling would promote the inducibility of VA, which could be prevented by cotreatment with spironolactone (A+Spiro), an aldosterone receptor antagonist and cardioprotective agent. In controls and each treatment group, we monitored: (1) electrocardiogram, ventricular electrogram, and arterial pressure before, during, and after bipolar electrical stimulation of the right ventricular outflow tract and apex at a strength 3× the pacing threshold, using both programmed stimulation with premature extra stimuli and 50-Hz burst pacing for 3 different durations; and (2) myocardial collagen volume fraction (CVF) as a marker of cardiac fibrosis. We found that VA (duration \u3e200 ms accompanied by declining arterial pressure) was more inducible (P \u3c 0.05) at 4 weeks (4 of 6) and with even greater frequency at 6 weeks (9 of 10) of ALDOST versus controls (0 of 6) and A+Spiro for 6 weeks (2 of 11). CVF (%) was proportionally increased (P \u3c 0.05) at 4 and 6 weeks (8.4 ± 0.74 and 13.9 ± 1.9, respectively) of ALDOST compared with control group (2.6 ± 0.4) and A+Spiro group (5.3 ± 0.7). However, the effective refractory period was indistinguishable between groups, whereas the probability of VA was nonlinearly related to CVF. Thus, in rats with aldosteronism, in which a reduction in effective refractory period was not evident, the mechanism for VA susceptibility is presumably linked to a decrease in conduction velocity and/or increased dispersion of refractoriness, probably caused by consequential myocardial fibrosis. Copyright © 2011 by Lippincott Williams & Wilkins

Chitra heart valve: results of a multicenter clinical study

Background and Aim of the Study: The Chitra tilting disc valve was developed in India to meet the need for a low-cost cardiac valve. The valve has an integrally machined cobalt-based alloy cage, an ultra-high molecular-weight polyethylene disc, and a polyester suture ring. An important feature of this valve is its soft closing sound, by virtue of a plastic occluder. Methods: Between December 1990 and January 1995, 306 patients underwent isolated aortic (AVR, n = 101) or mitral valve replacement (MVR, n = 205) at six institutions in India. The early mortality rate was 6.9% (seven after AVR; 14 after MVR). A total of 285 survivors was followed up until September 1998; total follow up was 1212 patient-years (pt-yr) (AVR, 445 pt-yr; MVR, 767 pt-yr). Results: There were 52 late deaths (4.3%/pt-yr; AVR 2.2%/pt-yr; MVR 5.5%/pt-yr). Thirty-five deaths were valve-related (23 were due to unknown causes). One AVR patient (0.2%/pt-yr) and 12 MVR patients (1.6%/pt-yr) developed valve thrombosis, and embolic episodes occurred in 25 patients (seven after AVR, 1.6%/pt-yr; 18 after MVR, 2.4%/pt-yr). Bleeding events and infectious endocarditis occurred infrequently (AVR 0.9 and 0.7%/pt-yr; MVR 0.4 and 0.5%/pt-yr, respectively). There was no incidence of paravalvular leak or structural dysfunction of the valve. Actuarial survival rates at seven years were 82.4+/-4.0% for AVR and 65.2+/-5.0% for MVR. During the same interval, thrombus-free and embolism-free survival after AVR and MVR occurred in 98.9+/-1.1% and 94.1+/-1.9%, and 92.3+/-2.8% and 82.1+/-5.7% of patients, respectively. Freedom from all valve-related mortality and morbidity at seven years was 81.5+/-4.1% after AVR, and 64.2+/-5.1% after MVR. Conclusion: The Chitra valve appears to be safe and to have performance comparable with that of other currently used tilting disc valves. This valve costs substantially less than other valves, and is therefore within reach of a larger subset of Indian patients

An analytical treatment of single station triaxial seismic direction finding

Copyright © 2005 Nanjing Institute of Geophysical ProspectingTriaxial seismic direction finding can be performed by eigenanalysis of the complex coherency matrix (or cross power matrix). By splitting the symmetric Hermitian coherency matrix C to D + E (where det(E) = 0 and D is diagonal), we shift unpolarized (or inter-channel uncorrelated) data into D and then E becomes 'random noise free'. Without placing any restrictions on the signal set—P, S, Rayleigh—matrix E has only one non-zero eigenvalue (at least for the case of a single mode arriving from a single direction). But for real data (polychromatic transients with correlated noise), it will have two non-zero eigenvalues. By rotating one axis of the triaxial geophone recorded signals to lie normal to the principal eigenvector, it is possible to reduce the coherency matrix from a 3 × 3 to a 2 × 2 matrix. For the case of a perfectly polarized monochromatic signal, we interpret this to mean that the particle trajectory can only be elliptical. It seems as though particles can only move in a plane: they cannot move in three dimensions. In practice, the signal is made up of a band of frequencies, there are multiple arrivals in the time window of interest, and noise is invariably present, which causes the ellipse to wobble in a 3D orbit. Explicit analytical expressions are derived in this paper to yield the eigenvalues and eigenvectors of the coherency matrix in terms of the triaxial signal amplitudes and phases.S Greenhalgh, I M Mason and B Zho