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Biomedical subjects

J E Magney

Publications and source records attributed to J E Magney.

8 recordsLinked to original sources
PubMed1996

The mechanisms of positional dysfunction of subclavian venous catheters.

PURPOSE: To determine the origin of subclavian vein catheter and lead dysfunction. MATERIALS AND METHODS: Cineradiography was performed on 10 patients with subclavian venous catheter dysfunction and three patients with pacemaker or defibrillator lead dysfunction. The leads and catheters were removed and replaced with use of a fluoroscopically guided technique; the needle entered the vein lateral to the first rib. Repeat cine examinations were performed following placement of new catheters. RESULTS: The cause of the dysfunction of all 10 catheters was shown to be pinch by the subclavicular musculotendinous tissues as the catheter passed below the clavicle toward its entry into the vein. All three leads were entrapped in the subclavicular tissues and stretched during abduction. The abnormal motion and clinical problems were eliminated after replacement. CONCLUSION: Subclavian catheter and lead malfunction is not due to compression between the first rib and the clavicle. It is due to entrapment in the subclavius muscle-costoclavicular ligament complex, which binds or compresses the device during movements. These problems can be avoided by employing fluoroscopically guided puncture techniques that enter the vein lateral to the first rib.

Catheterization, Central Venous↗
PubMed1995

Pacemaker and defibrillator lead entrapment: case studies.

Cadavers and cineradiographic analysis have been used to document the effects of the medial subclavicular musculotendinous complex (MSMC) upon lead function. Four cadavers with pacemakers were dissected and photographed to demonstrate the course a lead takes as it passes through the costoclavicular region. One lead had been placed into the cephalic vein. In the other three cadavers, leads placed by currently accepted techniques of subclavian venipuncture were all found to pass through the soft tissues of the subclavicular region before entering the venous system. Cineradiographic results from a patient with a defibrillator, taken before and after replacement of a broken lead, show the effect of clavicular motion on a lead that passes through the MSMC. Furthermore, cineradiography makes it possible to identify the point where the lead entered the vein, and whether or not it escaped being caught up in the soft tissues of the MSMC.

Cadaver↗
PubMed1993

A new approach to percutaneous subclavian venipuncture to avoid lead fracture or central venous catheter occlusion.

Pacemaker and defibrillator leads and central venous catheters placed by commonly recommended techniques have been found to pass through the subclavius muscle, the costocoracoid ligament, or the costoclavicular ligament before entering veins medial to the first rib. Entrapment by these soft tissues subjects leads and catheters to stresses imposed by movements of the ipsilateral upper extremity. Accordingly, a new approach has been developed that introduces the lead or catheter into the subclavian vein near the lateral border of the first rib. This placement avoids soft tissue entrapment and may extend the longevity of leads and catheters.

Bloodletting↗
PubMed1993

Anatomical mechanisms explaining damage to pacemaker leads, defibrillator leads, and failure of central venous catheters adjacent to the sternoclavicular joint.

The literature suggests that approximately 93% of all pacemaker lead fractures occur in the segment of the lead lateral to the venous entry, and costoclavicular compression has been implicated. While blood vessels can be compressed by movements of the clavicle, our research suggests that lead and catheter damage in that region is caused by soft tissue entrapment rather than bony contact. Dissection of eight cadavers with ten leads revealed that two entered the cephalic vein, and were not included in the study. Of the other eight leads, four passed through the subclavius muscle, two through the costoclavicular ligament, and two through both these structures before entering the subclavian, internal jugular, or brachiocephalic vein. Anatomical studies demonstrated that entrapment by the subclavius muscle or the costoclavicular ligament could cause repeated flexing of leads during movements of the pectoral girdle. Cineradiology of patients with position dependent catheter occlusion confirmed entrapment by the subclavius muscle. Soft tissue entrapment imposes a static load upon leads and catheters, and repeated flexure about the point of entrapment may be responsible for damage previously attributed to cyclic costoclavicular compression.

Arm↗
PubMed1986

Scanning electron microscopy of isolated epithelium of the murine gastrointestinal tract: morphology of the basal surface and evidence for paracrinelike cells.

By using the method of Bjerknes and Cheng, isolated murine gastrointestinal epithelial sheets were prepared for scanning electron microscopy. Examination of isolated epithelium from fundic stomach revealed numerous branched gastric glands. Parietal cells were easily detected bulging from the basal surface of the glandular epithelium. The basal surface membrane of parietal cells appeared smooth, with only sparse microvilluslike projections, whereas adjacent glandular cells had numerous 1- to 2-micron fingerlike projections which interdigitated laterally with similar processes from adjacent cells. Occasionally, paracrinelike cells having long cytoplasmic processes ranging from 10 to 20 micron in length were observed on the basal epithelial surface of the stomach and the colon, but not the small intestine. In isolated intestinal epithelia, the basal surface of crypt epithelial cells showed extensive cytoplasmic interdigitations, but no distinct morphology permitting recognition of individual cell types. Various stages of intestinal crypt bifurcation were seen. Craterlike spaces in the basal surface of crypt epithelium, presumably due to migrating leukocytes, were also numerous. Examination of the luminal surface of the isolated intestinal epithelium revealed that intimate associations between epithelium and mucosal-associated microorganisms were maintained, thus suggesting that minimal alterations in surface morphology were incurred by epithelial isolation. These observations on epithelial structure suggest that isolated gastrointestinal epithelia may be well suited for physiological studies of epithelial function and interactions with the microbial flora.

Animals↗