PURPOSE: To determine the axial and lateral resolution of a rotating intravascular ultrasound system and the diagnostic implications for the diagnosis of early artherosclerosis. METHODS: The resolution of a 20 MHz rotating transducer was tested in a specially designed high-resolution phantom and in five aortic autopsy specimens with varying degrees of early atherosclerosis. RESULTS: The best lateral resolution is at the minimal distance between transducer and object. Measurements in the wire phantom showed this to be better than 0.43 mm. This is less than the axial resolution which is better than 0.13 mm. Decreasing lateral resolution with increasing distance between transducer and object is manifested by arcing and overestimation of the extent of focal atherosclerotic lesions. CONCLUSION: Axial resolution is significantly better than lateral resolution. Rapid deterioration of lateral resolution affects the diagnostic ability to characterize the extent of early atherosclerosis. Eccentric positioning of the transducer tip, particularly in larger vessels, will therefore influence diagnostic accuracy in vivo.

Adolescent↗

PubMedDate not supplied

Radiologic diagnosis of different types of pulmonary stenoses.

Right ventricular outflow obstructive lesions are among the most prevalent congenital cardiac anomalies with a frequency ranging from 6--10% when considered as isolated anomalies. As part of a more complicated developmental complex, their frequency is undoubtedly higher. The diagnosis can be suspected by the traditional clinical and hemodynamic findings, but a firm diagnosis can only be made by angiography. An exact diagnosis is most important since most of these lesions can be surgically corrected.

Cardiomegaly↗

PubMedDate not supplied

Percutaneous intravascular biopsy using a Simpson atherectomy catheter: technical note.

The design of the Simpson atherectomy catheter makes this device a potentially safe and technically easy tool to obtain adequate pathologic intravascular or intraluminal specimens. The risk of perforation should be low, but this use has to be further studied. We describe the first intravascular biopsy performed with the Simpson catheter.

Arteriosclerosis↗

PubMedDate not supplied

The biocompatibility of compressed collagen foam plugs.

The tissue reaction to reexpanded, purified bovine collagen sponge placed percutaneously into the lung, pleural space, liver, kidney, and muscle was studied in dogs and rabbits. In addition, the biocompatibility and radiopacity of tantalum-treated collagen foam plugs was examined. No adverse effects were found. We believe that collagen plugs may be of use in occluding needle tracts from biopsy sites to prevent complications such as bleeding or pneumothoraces.

Animals↗

PubMedDate not supplied

The incidence of myocardial bridges in heart transplants.

Coronary angiograms of 64 heart transplant patients were reviewed to determine the incidence of myocardial bridges. In 33% of the patients, myocardial bridges were detected, almost exclusively across the midportion of the left anterior descending coronary artery. The incidence is higher than previously reported in the literature and is thought to be related to increased stiffness and hypertrophy of the myocardium, which facilitates angiographic detection of myocardial bridges in the transplanted heart.

Adult↗

PubMedDate not supplied

Reversible hepatic transplant ischemia: case report and review of literature.

We report the successful treatment of a hepatic arterial anastomotic stenosis by angioplasty in an orthotopic liver transplant recipient. The patient had already undergone hepatic infarction and compromised allograft function and sepsis. Baseline duplex ultrasound and angiographic studies showed obstruction of the transplant arterial anastomosis. Following angioplasty, allograft function, areas of infarction, and duplex ultrasound studies returned to normal. At 6-month follow-up the patient remains asymptomatic.

Adolescent↗

PubMedDate not supplied

A stepless needle-dilator for expedient percutaneous catheterization: technical note.

A new stepless needle-dilator is described which allows arterial puncture and dilation in a single step using a single wall puncture technique. The new needle-dilator causes significantly less arterial damage than a conventional dilator (p less than 0.05). Additionally, time and cost savings are realized by clinical users.

Angiography↗

PubMedDate not supplied

Dialysis grafts arterial plug: retrieval using the tulip sheath device in vitro.

The "arterial plug" is a resistant thrombus that frequently persists at the arterial anastomosis of clotted hemodialysis grafts following thrombolytic therapy. We studied the physical and morphological characteristics of the plug and determined the feasibility of transcatheter removal in vitro using the tulip compression thrombectomy system. Sixteen thrombus plugs were recovered during surgical thrombectomy of clotted human dialysis grafts. The physical and gross physical characteristics of all plugs were analyzed. Eight specimens were evaluated microscopically. Transcatheter compression thrombectomy of eight plugs was attempted in vitro. Each plug was embedded in a polyvinyl tube filled with newly clotted blood and connected to a flow circuit. First, balloon-assisted aspiration thrombectomy (BAT) of soft thrombus was performed, while sparing the distal-most segment containing the plug. The tulip sheath was then introduced facing the "arterial end" of the tube. The thrombus segment containing the plug was pulled back into the tulip mesh using either a 3 Fr Fogarty balloon catheter or a self-expanding rake. The tulip was closed to compress and remove the trapped plug. Near-complete thrombectomy of soft clot was achieved in all tested tubes. Compression and retrieval of the entire arterial plug was successful in all except one, where only partial compression of the plug occurred, presumably due to fibrotic changes. No fragmentation or embolization occurred in the remaining procedures. Spongy consistency was noted in 94% of the specimens. Microscopic evaluation showed organized layered thrombus with compaction in five plugs. Transcatheter removal of a thrombus plug is feasible in vitro using the tulip compression-thrombectomy system.

Arteriovenous Shunt, Surgical↗

PubMedDate not supplied

Radiographic changes in the postoperative patient.

Explore the source record for details and available documents.

Adult↗

PubMedDate not supplied

Recirculation-type Amplatz clot macerator: determination of particle size and distribution.

PURPOSE: A high-speed mechanical clot macerator was tested in vitro, and the distributions and sizes of residual particles produced by this device were determined. MATERIALS AND METHODS: Human thrombi aged for 4 days and 10 days were macerated using a recirculation-type Amplatz thrombectomy device with an 8-F, high-speed screw propeller. The device was activated for 15, 30, and 60 seconds. Two different methods of particle measurement were used to determine overall particle distribution and to determine the size and number of large particles. RESULTS: The recirculation device liquefied 99.2% of 4-day-old and 98.8% of 10-day-old thrombi, producing particles ranging in size from 13 to 1,000 microns; all particles were smaller than 1,000 microns. Particle size and distribution results were identical for the 30-second and 60-second activation times. CONCLUSION: The recirculation-type thrombectomy device appears to perform well as a method of macerating human thrombi. Clinical trials need to be conducted to test the device further and to determine if it can be used safely on venous as well as arterial occlusions.

Humans↗

PubMedDate not supplied

Thermal ablation of the gallbladder.

Explore the source record for details and available documents.

Adenoma, Bile Duct↗

PubMedDate not supplied

Placement of the Palmaz stent with use of an 8-F introducer sheath and Olbert balloons.

PURPOSE: The authors describe a modified technique for delivering Palmaz 30-mm stents. MATERIALS AND METHODS: The modification is based on the use of an 8-mm Olbert balloon mounted on a 5.8-F shaft. The Palmaz stent is crimped onto the balloon by using finger pressure only. An 8-F introducer sheath can be used instead of a 10-F sheath. The surface material of the balloon prevents the stent from moving as it is introduced through the sheath and lesion. The balloon has a very small profile after deflation, which means it can be easily removed without dislodging the stent. The balloon can be used for placement of more than one stent. RESULTS: Nineteen Palmaz 30-mm stents have been placed with this method, and there have been no complications or difficulties related to this method. In one case, four stents were delivered by using the same balloon. CONCLUSION: This modification should reduce the complications of stent delivery, especially in small iliofemoral systems.

Arteries↗