Button self-retaining drainage catheter

To help improve patient acceptance of long-term internal/external catheter access to the biliary tract in those with benign biliary obstruction, a simple design allows the catheter end to remain flush with the skin. It consists of a clothes button affixed to the drainage catheter with a wood screw after the catheter has been cut off at the skin exit. This button/screw device has been used successfully in 22 patients over the last 10 years; catheter exchanges were easily accomplished.

Short-term effects of selective renal arterial carbon dioxide administration on the dog kidney

PURPOSE

The authors examined the nephrotoxicity of carbon dioxide injected directly into the renal arteries as an arterial contrast agent.

MATERIALS AND METHODS

Fourteen anesthetized dogs received selective renal infusions of CO2 ranging from a normal dose of 7 cm3/kg to high doses of 11-54 cm3/kg. Two dogs received conventional iodinated contrast media. The effects on renal function and histologic appearance were evaluated by means of radionuclide studies (iodine-131 iodohippurate sodium and technetium-99m dimercaptosuccinate) and histopathologic examination (light, transmission, and scanning electron microscopy).

RESULTS

Although there was a mean decrease in renal blood flow of 11.86% (standard error [SE], 7.1) immediately after the injection of CO2, flow had returned to baseline (0.17%; SE, 5.27) after 24 hours. Although the sample size was small, there was no dose-dependent effect of CO2 on renal function and histologic appearance. Mild histologic changes and one case of moderate acute tubular necrosis were seen only in cases in which the kidney was positioned vertically rather than laterally.

CONCLUSION

Although formal studies in patients are required, the results of this investigation suggest that CO2 may be a safe contrast agent and less nephrotoxic than existing contrast agents, providing care is taken to ensure that CO2 is not trapped in a vertically positioned kidney, as might occur in renal transplant recipients.

Use of transesophageal echocardiography to visualize an anomalous right coronary artery arising from the left main coronary artery (single coronary artery)

This case report demonstrates a role for transesophageal echocardiography in defining the course of anomalous coronary arteries. Origin of the right coronary artery (RCA) from the left main (LM) (single coronary artery) is an exceedingly rare congenital anomaly. It is not always benign and may result in myocardial infarction. This may be due to compression between the aorta and the pulmonary artery. Transesophageal echocardiography offers a low-risk, noninvasive means of imaging the proximal coronary arteries. In the majority of patients, the proximal segments of the three major coronaries can be clearly visualized. With the addition of color flow, it is possible to visualize flow in most patients. Proximal obstructive lesions can be seen in some patients although sensitivity thus far seems low.

Carbon dioxide as an angioscopic medium. Comparison to various methods of saline delivery

The limitations of angiography, when it is used as the sole method of vascular assessment, are increasingly apparent as vascular intervention becomes more sophisticated. Angioscopy could be an adjunctive diagnostic modality by differentiating among thrombus, dissection, and atheroma, and by monitoring the response to therapy. However, angioscopy requires a blood-free field for adequate visibility, and this may be difficult to obtain. The feasibility of carbon dioxide (CO2) and various saline delivery methods for clarifying the viewing field for percutaneous angioscopy was investigated. Angioscopy of femoral and iliac arteries on nine dogs was performed. Saline was infused by hand injection, pressure bag infusion, or mechanical power injection, and CO2 gas was injected using a special gas injector. The clarity of the viewing field was graded for each medium and method. Excellent quality antegrade femoral angioscopy was obtained with CO2. The superiority of CO2 injection in comparison with power-injected saline approached statistical significance (P = .06). Power-injected CO2 and power saline were superior to hand-injected or pressure bag-injected saline for maintaining sufficient visibility. Retrograde iliac angioscopy was possible without inflow occlusion, but required high flow rates (only possible with power-injected saline or CO2). CO2 injected under controlled circumstances holds promise as a medium to improve angioscopic visibility.

Perivalvular pseudoaneurysm complicating bacterial endocarditis: MR detection in five cases

Bacterial endocarditis usually affects the valve leaflets, but erosion into the valve anulus and adjacent myocardium may form a myocardial abscess. Perivalvular abscesses can drain into the ventricles or aorta, forming a life-threatening pseudoaneurysm. We reviewed our experience with cardiac MR imaging of this disorder. Fourteen patients with complicated bacterial endocarditis underwent ECG-gated spin-echo cardiac MR imaging in addition to conventional duplex two-dimensional echocardiography (2-D echo). Angiography was performed in seven patients, six of whom underwent surgery for valve replacement. MR imaging detected the pseudoaneurysms in all five of the surgically proved cases, while 2-D echo detected only three. Clinical follow-up suggested there were no false-negative examinations, but no autopsy data were available for confirmation. Postoperative MR imaging studies were conducted in three patients, revealing two recurrent pseudoaneurysms and one thrombosed aneurysm. Cardiac MR imaging provides useful pre- and postoperative information in patients with perivalvular pseudoaneurysms due to endocarditis.

A solution to the problem of high-flow jets from miniature angiographic catheters

In this study we evaluated methods for reducing high-flow jets from 5-French catheters that occur when injection pressures approach catheter tolerance (1000 psi [6.9 MPa]). This "jet effect" has been responsible for subintimal extravasation of contrast material in patients. We designed a physical model that accurately measures flow rates through the end hole and each side hole of 5-French high-flow catheters under simulated physiologic arterial pressure. When a standard catheter commonly used for injection of contrast material was studied, flow of contrast material was 34% through the end hole and 31% through the distal side-hole pair at high injection pressures (1000 psi). We examined the effect of altering the size and configuration of catheter side holes and end hole in an effort to create an improved flow profile, and thus a safer angiographic catheter. End-hole flow rate was reduced by 73% to 9% of total flow by tapering the 5-French catheter to 0.018 in. (0.046 cm) and by using smaller 0.015-in. (0.038-cm) side holes for even flow distribution. The high-flow jets present with standard high-flow 5-French catheters do not occur when flow-restrictive end holes and side holes are used. A uniform flow profile can be obtained without sacrificing delivery of contrast material through small catheters.

Guide-wire reinforcement and lengthening with coaxial locking guide wires: the crimping technique

The authors developed a technique to increase the size of a guide wire and permit single-step placement of catheters and large sheath systems over previously inserted small-caliber guide wires. The technique involves compression of metal cannula against a smaller in-dwelling wire or inner cannula. It has been used successfully during laser-assisted balloon angioplasty and percutaneous nephrolithotomy.

New high-flow "cloud" catheter for safer delivery of contrast material

The authors describe a new angiographic catheter, which delivers equal flow rates through the side holes and reduced flow through the end hole compared with conventional catheters. Computer analysis of catheter-flow models revealed that placement of larger side holes proximally and smaller side holes distally produces more uniform flow rates out of the holes. This decreases the risk of potentially hazardous delivery of high-pressure jets of contrast material from the end hole. The flow pattern is so uniform that it resembles a cloud of contrast material on injection. This catheter design is particularly applicable for 3-5-F catheters, which require high-pressure injections. Clinical testing in 50 cases revealed no extravasations or unintentional selective injections with use of this catheter.

Miniaturization of catheter systems for angiography

Miniature techniques offer many advantages for performance of routine angiography, as well as invasive vascular procedures. On the basis of the authors' experience with over 16,000 diagnostic and interventional procedures, this report describes the equipment and methods used for miniangiography. Development of sturdy, high-flow 3-5-F catheters and 0.014-0.018-inch guide wires, combined with the use of small needle puncture techniques, has improved the safety of angiography and intervention such that outpatient procedures are now routine. Miniature catheter systems are now preferable to larger catheter systems in most instances.

Improved detection of healed myocardial infarction by Fourier amplitude and phase imaging in two projections: validation with MRI

Biplane Fourier amplitude and phase images from radionuclide ventriculograms were analyzed for the presence of regional wall motion abnormalities in 25 patients who had a total of 33 healed myocardial infarctions (nonviable scar tissue) documented by contrast ventriculography and ECG. This indirect evidence was validated by MRI, which permits direct visualization of healed myocardial infarction. The use of amplitude and phase images in both projections resulted in the detection of more healed myocardial infarctions (91%) than did the use of conventional radionuclide ventriculography with left anterior oblique images alone (67%), because inferior wall infarcts are more readily visualized in the left posterior oblique projection.

Preoperative evaluation of the thoracic aorta using MRI and angiography

The ability of ECG-gated magnetic resonance imaging (MRI) to evaluate disease of the thoracic aorta compared with angiography was prospectively assessed in 28 patients. MRI identified abnormalities in all patients, with confirmation at operation in 22 (79%) and by angiography alone in all 28. In 20 of the patients, MRI correctly diagnosed 20 of 21 aneurysms of the thoracic aorta (6 dissecting, 4 saccular, 10 fusiform), but 1 surgically proven fusiform aneurysm was categorized as an enlarged aortic dissection based on both MRI and angiographic findings. One dissection and 1 fusiform aneurysm were shown by MRI only. Coarctation of the aorta was identified in 4 patients. Ascending aortic enlargement and left ventricular hypertrophy were identified by MRI in 4 patients with aortic stenosis. In 7 patients (25%), MRI provided additional important information not shown by angiography and in 1 patient, the MRI findings resulted in a change in the surgical approach. In 14 of 28 patients (50%), angiography was necessary for definitive preoperative evaluation of the aortic valve, the coronary arteries, or the brachiocephalic vessels. MRI was a useful noninvasive supplement to angiography for the preoperative assessment of thoracic aortic disease.

Evaluation of an aortic annular pseudoaneurysm by MRI: comparison with echocardiography, angiography and surgery

Nuclear magnetic resonance imaging (MRI) was clinically useful in a case of aortic annular pseudoaneurysm complicating bacterial endocarditis. The MRI findings were proven by angiography and surgery. Although surgical correction was attempted, the aneurysm recurred and has been followed by MRI and two-dimensional echocardiography. In addition to two-dimensional echocardiography, MRI represents a useful noninvasive imaging method for diagnosis and follow up of aortic annular pseudoaneurysm.

MR imaging of blood pool signal variation with cardiac phase in aortic dissection

Electrocardiographic gated magnetic resonance imaging of the thoracic aorta was performed on a patient with aortic dissection. Magnetic resonance demonstrated the intimal flaps and double lumina, allowing correct classification of the dissection as proven surgically. The blood pool signal in the false lumen was low during diastole and higher during systole, which has not been previously described. This signal pattern allows definition of false luminal patency using a single spin-echo pulse sequence.

Assessment of left ventricular wall thickness in healed myocardial infarction by magnetic resonance imaging

The ability of magnetic resonance imaging (MRI) to detect and localize healed myocardial infarction (MI) was assessed. Seventeen consecutive patients with healed MI assessed by biplane contrast ventriculography underwent MRI using oblique imaging planes. Seven normal subjects underwent MRI as controls. In each patient, ventriculography identified regional wall motion abnormalities. MRI, performed with a 0.15-Tesla resistive magnet and oblique imaging planes relating to the left ventricle, detected zones of regional wall thinning conforming to the wall motion abnormalities localized by ventriculography in 16 patients. In these patients, adjacent areas of intact myocardium were identified in areas shown by ventriculography to be normal. The left ventricular wall thickness at the site of MI was significantly less than adjacent noninfarcted myocardium (p less than 0.001) and normal hearts (p less than 10(-6)). The ratio of the thickness of the infarct to adjacent normal wall averaged 0.40 (range 0.22 to 0.62). MRI could differentiate healed MI from adjacent noninfarcted myocardium and normal hearts.

Double loop receiver coil for MR imaging at 0.15 T

A receiver coil of a cross-coupled, double loop geometry has been developed. This coil has a higher signal-to-noise (S/N) ratio and more homogeneous signal intensity at increasing depth than a conventional surface coil. Improvements in S/N of 51-256% compared with the commercial half-saddle body coil have been demonstrated in a 0.15 T resistive instrument. The new coil permits reduction in pixel volume using higher field gradients and thinner slices or time savings using fewer signal averages. The double loop coil provided higher S/N for lumbar spine imaging than an oval surface coil. Limitations of this type of coil design are increased sensitivity to respiratory motion artifacts and limitation of the size of the subject that may be imaged. Using the double loop coil, the capability of our instrument to image the heart, pelvis, hip, and shoulder has been substantially improved.

Importance of imaging plane for magnetic resonance imaging of the normal left ventricle

Visualization of the left ventricle by magnetic resonance imaging (MRI) is largely a function of imaging planes. The best depiction of the myocardium is possible when the imaging plane is perpendicular to the region of interest. The effect of imaging plane on the visualization of the left ventricle has not been fully described. To assess this effect, 10 normal adults underwent electrocardiogram-gated multiplanar cardiac MRI. The imaging planes being evaluated were standard planes, transverse, sagittal and coronal, and modified planes relating to the left ventricular (LV) long axis: coronal long axis parallel to the ventricular septum (VS), sagittal long axis perpendicular to the VS and transverse short axis perpendicular to the VS and long axis. The myocardium was separated into 9 segments. Using each plane, the LV segments were evaluated for quality of LV depiction. The planes based on the LV long axis were superior to standard planes in depicting the LV segments.