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Biomedical subjects

F S Keller

Publications and source records attributed to F S Keller.

At least 19 recordsLinked to original sources
PubMed1992

Transcatheter embolization of a high-flow congenital intrahepatic arterial-portal venous malformation in an infant.

An intrahepatic arterial-portal venous malformation (APVM) was diagnosed in a 4 1/2-month-old infant with portal hypertension. Visceral angiography showed a large saccular vascular space in the left hepatic lobe with a multiplicity of feeding arteries and drainage into the left portal vein. The lesion was successfully treated by transcatheter embolization following two unsuccessful surgical procedures. Two years later portal vein thrombosis with cavernous transformation was diagnosed, possibly a consequence of the high-flow arterial-portal shunt and its subsequent occlusion. Knowledge of the anatomic differences between this rare congenital APVM and the more commonly occurring arterial-portal fistula is crucial in planning effective transcatheter embolotherapy or surgery for these lesions.

Arteriovenous Fistula↗
PubMed1992

In vitro comparison of the spiral Z stent and the Gianturco Z stent.

A new spiral Z stent is described, and its characteristics are compared in vitro with those of the modified Gianturco Z stent. The spiral Z stent has a more uniform expansile force throughout its effective length; is more compressible, thus allowing for use of a smaller introductory catheter; and is more stable than the modified Z stent. Flexibility of both stent types is similar. Advantages of the spiral Z stent promise to be beneficial for clinical use.

Equipment Design↗
PubMed1991

Sequential 2D inflow venography: initial clinical observations.

Sequential 2D inflow NMR (SDI) venography was employed to define venous anatomy and pathology in five healthy subjects and five patients, mean age 48 +/- 7 years, with documented deep vein thrombosis. SDI images were graded independently by two observers on a scale of 1,2 nondiagnostic and 3,4 diagnostic categories. All iliac and femoropopliteal SDI venograms were diagnostic. In contrast, only one out of nine calf SDI venograms was diagnostic. SDI is a promising new method to assess the proximal peripheral venous system. Improved imaging strategy is needed to produce flow images of the calf veins.

Femoral Vein↗
PubMed1991

Urokinase infusion: feasibility of monitoring for complications in a non-intensive care setting.

In an effort to more effectively use critical care facilities and to reduce costs, during a 2 1/2-year period, the condition of 32 patients who received 37 local intraarterial urokinase (UK) infusions was monitored in a non-intensive care unit (ICU) setting. Techniques of infusion, mean total dose of lytic agent used (1.7 million IU), and mean duration of infusion (22 hours) were similar to those reported previously in series of patients monitored in the ICU. Complete lysis (no angiographically detectable residual clot within the treated segment) was achieved in 28 of 37 infusions (76%). Major complications occurred during two infusions (5.4%). In 33 of the 37 cases, systemic heparin was administered during UK infusion. No cases of pericatheter thrombosis were encountered. At the authors' institution, patients can be safely monitored during local UK infusion in a non-ICU setting without compromising effectiveness of therapy. This approach has resulted in enhanced cost-effectiveness of thrombolytic therapy and more effective use of critical care facilities.

Cost-Benefit Analysis↗
PubMed1991

Peripheral arterial occlusive disease: prospective comparison of MR angiography and color duplex US with conventional angiography.

Conventional angiography, two-dimensional inflow magnetic resonance (MR) angiography, and color duplex ultrasound (US) were performed on 12 patients in a blinded, prospective study. The ability to grade arterial lesions and plan revascularization interventions were compared. Arterial lesions were categorized as nonsignificant (0%-49% diameter reduction) or significant (50%-100% diameter reduction). Determination of nonsignificant and significant lesions with MR angiography was in agreement with that at conventional angiography in 100 of 140 lesions (71%). Agreement between results of conventional angiography and color duplex US occurred with 114 of 123 infrainguinal lesions (93%). Twenty-one vascular interventions were planned by using conventional angiography; there was agreement with color duplex US in 11 cases and MR angiography in five. Color duplex US performed well in the assessment of infrainguinal disease but was limited in the evaluation of iliac segments because of nonvisualization. The iliac region was visualized in more patients with MR angiography than with color duplex US, but image quality with MR angiography was inconsistent. Strategies to improve MR angiography of the peripheral vasculature merit further study.

Aged↗
PubMed1990

Meckel's diverticula: angiographic diagnosis in patients with non-acute hemorrhage and negative scintigraphy.

Meckel's diverticula were detected by mesenteric angiography in 2 patients with unexplained gastrointestinal bleeding following negative barium, endoscopic, and scintigraphic evaluation. Abnormal, irregular, arterial branches supplied by an elongated, nonbranching ileal artery and an associated capillary stain were present in each case. Since neither diverticulum was bleeding at the time of angiography, focal contrast extravasation was not present. Superselective magnification angiography, evacuation of contrast from the urinary bladder, and careful patient positioning significantly improved the visibility of these lesions. Visceral angiography performed with meticulous attention to technical detail can be diagnostic of Meckel's diverticulum, even in the absence of acute hemorrhage.

Adolescent↗
PubMed1990

Anomalous origin of bronchial arteries: potential pitfall of embolotherapy for hemoptysis.

Bronchial artery embolization was performed in two patients with anomalous origins of the bronchial artery. In one patient, the anomalous bronchial artery originated from the convex surface of the aortic arch between the origins of the brachiocephalic and left carotid arteries, while in the other, it originated from the internal mammary artery. Anomalous bronchial arteries represent a potential pitfall during bronchial artery embolization. Radiologists involved in embolotherapy for hemoptysis should therefore be alerted to the possible presence of anomalous bronchial arteries, especially when significant bronchial artery supply to areas of abnormal pulmonary parenchyma is not demonstrated at a catheter search or aortography of the descending aorta. In these instances, arch aortography should be performed to identify anomalous origins of the bronchial arteries or other nonbronchial systemic collateral vessels.

Adult↗
PubMed1990

Renal artery stenosis: prospective evaluation of diagnosis with color duplex US compared with angiography. Work in progress.

A prospective, double-blind comparison of color duplex sonography with angiography was performed for diagnosing renal artery stenosis in 50 kidneys in 26 patients. The major criterion for diagnosing a diameter narrowing of more than 50% was a velocity of greater than 100 cm/sec. Angiography demonstrated 10 stenoses and one occlusion in main or accessory renal arteries in seven patients. Twenty-two percent of kidneys had accessory renal arteries. Color duplex scanning helped identify 58% of the main arteries and no accessory vessels. None of the stenotic vessels were identified with duplex scanning, but the single occluded vessel was correctly diagnosed. Nine of the 29 vessels identified with duplex scanning were incorrectly diagnosed as stenotic, findings yielding a specificity of 37%. The authors conclude that the published velocity threshold of 100 cm/sec is too low. Duplex scanning with current technology is unlikely to prove satisfactory for screening patients with hypertension for renal artery stenosis.

Adult↗
PubMed1990

Tube tamponade: potential pitfall in angiography of arterial hemorrhage associated with percutaneous drainage catheters.

Diagnostic angiography performed to search for a source of hemorrhage in three patients with percutaneous transhepatic biliary catheters and one patient with a percutaneous nephrostomy catheter was initially unrewarding when performed with the drainage catheter in place. In each patient, removal of the drainage catheter resulted in severe pulsatile hemorrhage from the parenchymal tract and allowed angiographic localization of the bleeding site. Temporary control of the hemorrhage was then obtained by inflating an angioplasty balloon within the tract. Transcatheter embolotherapy provided definitive control of bleeding in three patients. When initial angiographic evaluation for bleeding in patients with percutaneous biliary and nephrostomy catheters fails to depict a source, the study should be repeated immediately after removal of the drainage catheter. Because hemorrhage can be severe once tamponade is relieved, the drainage catheter should be withdrawn over a guide wire so that a tamponading catheter can be rapidly reinserted to control hemorrhage until more definitive therapy is undertaken.

Aged↗
PubMed1990

Transcatheter thrombosis of a leaking saccular aneurysm of the main renal artery with preservation of renal blood flow.

Percutaneous techniques have been used in the treatment of aneurysms and pseudoaneurysms in a variety of anatomic locations, including the kidney. An elderly patient with a leaking saccular aneurysm of the main left renal artery was considered a poor operative risk. We were able to embolize and thrombose the aneurysm selectively by using a combination of coil springs, guidewire, thrombin, and bucrylate without occluding the renal artery.

Aged↗
PubMed1989

Incidence and clinical significance of subclinical scrotal varicoceles.

A total of 40 infertile men with a normal physical examination underwent gonadal venography to determine the presence of a subclinical varicocele. Of the patients 19 had a left and 3 had a right subclinical varicocele. A total of 21 patients underwent radiographic occlusion of the varicoceles, while 1 required surgical ligation of the internal spermatic vein. Of the 22 patients 13 have been followed for greater than 6 months after correction of the varicocele. In these patients there has been a small but significant increase in sperm number after varicocele occlusion. No significant changes in either sperm motility or morphology have occurred. Although most patients do not have any major improvement after occlusion of a subclinical varicocele, some may experience a significant improvement in sperm number after occlusion. The effect on pregnancy rates is not yet known.

Adult↗
PubMed1989

Acquired diseases of aberrant subclavian arteries.

The anatomic, clinical, and radiologic findings of aberrant subclavian arteries (ASAs) are well known. Acquired diseases such as aneurysms, dissections, or stenosis can complicate these anomalies. We propose that these complications are a result of atherosclerosis caused by abnormal turbulence around the ASA. Comparisons of computed tomographic and angiographic measurements of subclavian arteries in adults with and without arch anomalies and angiographic measurements of ASAs in children show that ASAs dilate in older patients. We describe six patients with acquired diseases of ASAs or the aorta adjacent to the ASA. Aneurysms, aortic dissections, and stenosis were each found in two patients. Problems in the radiologic diagnosis and clinical management of these diseases are emphasized. Radiologists should be cognizant of the significance of ASAs in patients with aortic aneurysms and dissections.

Adult↗
PubMed1989

Chronic arteriovenous fistulas masquerading as arteriovenous malformations: diagnostic considerations and therapeutic implications.

Arteriovenous fistulas (AVFs) and arteriovenous malformations (AVMs) may be difficult to differentiate angiographically, and this differentiation has important therapeutic implications. In five cases of chronic AVF, four originally misdiagnosed as AVMs, superselective angiography enabled the correct diagnosis. In two plantar arch fistulas, the technique was further enhanced by manual compression of arterial inflow to decrease the rate of blood flow through the fistula. All five AVFs were successfully occluded. The authors conclude that AVFs and AVMs can be distinguished by means of the appropriate angiographic techniques.

Adult↗