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Biomedical subjects

K Amplatz

Publications and source records attributed to K Amplatz.

At least 55 records · Page 3Linked to original sources
PubMed1989

Atheroablation with the Kensey catheter: a pathologic study.

The mode of action of the Kensey catheter, a new atheroablation device, was investigated. Fresh above-the-knee amputated legs were used for recanalization of the superficial femoral artery. The variables used were identical to those of clinical trials, including a rotational speed of 50,000 rpm and an injection rate of 40 mL/min. The debris produced by the catheter was studied cytologically, and the arterial segments were examined histologically. The particle size in the debris ranged from 1 to 2,000 microns. The softer plaques produced a fine fibrin dust background with long strips of intima ranging from 10 to 2,000 microns. Complicated calcified plaques produced larger background material (10-120 microns) but smaller strips of intima (50-800 microns). Dissections and perforations occurred. Some of the debris produced by the atheroablation process was used to embolize a canine heart and kidney. Small focal infarctions were found in the heart, and large and multiple infarcts were seen in the kidney. In clinical studies the debris appears to be tolerated in the lower extremities. Its safety in the kidney and heart are questioned.

Angioplasty, Balloon↗
PubMed1989

Aorta balloon angioplasty: 9-year follow-up.

Nine-year patency and clinical effectiveness of balloon angioplasty of the aorta in a patient with Leriche syndrome are described. The morbidity of surgical intervention for aortoiliac disease is compared with that of percutaneous transluminal angioplasty. These results suggest that aortic balloon angioplasty is a safe and effective procedure with good long-term results.

Angioplasty, Balloon↗
PubMed1989

Mechanical clot dissolution: new concept.

The authors present preliminary data on in vitro mechanical clot dissolution by means of a catheter with a tiny high-speed propeller enclosed in a special housing. Preweighed human blood clots were subjected to the catheter in a test tube with saline at various propeller speeds and durations of application. After filtration of the resultant slurry, the clot residue was weighed and examined histologically. Clot dissolution was found to be related to both the duration and speed of propeller rotation. No fibrin residue was seen after dissolution, although potential embolic material, composed of clumps of cellular debris as large as 208 microns in longest dimension, was found. Mechanical clot dissolution could possibly be used in any natural or synthetic blood vessel in which there is acute or subacute thrombosis, with fewer complications and lower cost than obtained with traditional methods.

Catheterization↗
PubMed1989

Experience with the Amplatz retrievable vena cava filter.

The Amplatz retrievable inferior vena cava filter was designed to be used as either a permanent indwelling filter or a short-term, percutaneously removable filter. The authors placed 52 filters in 52 patients. No deaths occurred as a result of filter placement or usage. Follow-up in 42 (81%) patients included inferior vena cavography (n = 31), computed tomography (n = 4), duplex ultrasound (n = 4), and autopsy (n = 3). Inferior vena cava thrombosis was found in seven (17.5%) of the 40 previously nonobstructed venae cavae studied. Two patients with caval thrombosis required a second filter to prevent embolization of thrombus that had extended to the lung side of the first filter. No clinically evident pulmonary emboli after filter placement have been noted. Six filters were successfully retrieved or repositioned percutaneously. The relatively high rate of caval thrombosis with extension above the filter may be due to a higher trapping efficiency or to filter geometry. The role of this filter in the treatment of deep venous thrombosis and pulmonary emboli is unclear.

Adult↗
PubMed1989

Double-lumen needle for percutaneous ureteral pressure-flow studies.

Ureteral perfusion studies in patients without preexisting renal access currently must be intermittently interrupted for intrarenal pressure measurement. A double-lumen needle has been successfully placed in four patients (two with native and two with transplanted kidneys). This permits simultaneous perfusion and intrarenal pressure monitoring yet maintains the safety and ease of use of a single skinny needle.

Humans↗
PubMed1989

Aid for safer sclerotherapy of the internal spermatic vein.

A device was developed for use during sclerotherapy to treat spermatic varicoceles. It is used to provide external compression of the internal spermatic vein, to prevent distal flow of the sclerosing agent into the scrotal venous network. The device has been successfully used in 27 patients (43 spermatic veins). In no case did sclerosing agent leak past the compressor, and no complications related to the compressor itself have been encountered.

Equipment and Supplies↗
PubMed1989

Retrograde left atrial catheterization.

Catheterization of the left atrium can provide valuable information about both congenital and acquired heart disease. The traditional approach to examination of the left atrium has been the transseptal route, which has occasionally been associated with serious complications. A method of retrograde left atrial catheterization has been developed that is performed with a modified standard catheter. The technique was tested in five dogs and was easy and safe to perform.

Animals↗
PubMed1989

The importance of separation of prostatic lobes in relief of prostatic obstruction by balloon catheter urethroplasty: studies in dogs and humans.

We performed balloon urethroplasty in six older normal dogs and 10 patients with benign prostatic hypertrophy to establish the mechanism by which this technique results in relief of bladder outlet obstruction. Thirty-millimeter balloon catheters were used in both the animal and human studies. Autopsy studies showed disruption of the anterior prostatic commissure in four of the six dogs, disruption of both anterior and posterior commissures in one dog, and no disruption in the remaining dog. In all 10 patients, cystoscopy and urethrography showed disruption of the anterior commissure. Separation of the prostatic lobes by disruption of the prostatic commissures may be the most important mechanism by which balloon urethroplasty relieves urethral obstruction.

Animals↗
PubMed1988

In vitro evaluation of caval filters.

This experiment demonstrated the clottrapping ability of two commercially available filters, the Mobin-Uddin and Greenfield, and three experimental filters developed by Amplatz, Günther, and Gianturco. Each filter was tested in a polyethylene tube simulating the inferior vena cava. Separate series of 10 clots, each 3 cm long and 6 mm or 9.2 mm in diameter, were exposed to the test filter. The Mobin-Uddin and Amplatz filters failed by overload: acutely elevated pressures forced clots outside the skirt of the former, and between the limbs of the latter. The Günther filter trapped all incident clots, but migrated downstream when occluded by clot. The Greenfield filter passed clots at normal pressures between its widely spaced legs. The Gianturco (bird's nest) passed clots at normal pressures as well. While filters performed suboptimally, strengthening the anchoring struts of the Günther filter would result in a secure, effective filter.

Animals↗
PubMed1988

Effects of dilating the canine pulmonary annulus with two balloons. Doppler ultrasound and postmortem findings.

Simultaneous inflation of two balloons may be necessary for balloon dilation valvuloplasty in patients with a large annulus. We examined the cardiovascular effects of dilating the pulmonary annulus with two balloons in 18 normal dogs using pulsed Doppler ultrasound and gross and microscopic examination. When the ratio of the cross-sectional area (CSA) during dilation to the CSA of the pulmonary annulus was between 1.04 and 1.28, there was valvar regurgitation in only one dog, in which catheter manipulation was complicated by heartworms, and damage was confined to intimal changes. (The dog was killed 24 hours after dilation.) With ratios between 1.67 and 1.76 (equal to the CSA of a single balloon with a diameter 33% greater than the annulus), there was trivial or mild tricuspid or pulmonary regurgitation, and anatomic changes were more prominent but still superficial. Two animals killed after nine days had resolution of valvar regurgitation and healing damage. With CSA ratios greater than 2.00 or with balloon rupture, myocardial damage and laceration of the pulmonary arteries resulted. Simultaneous inflation of two balloons within the right ventricular outflow tract with CSA ratios of up to 1.76 results in minimal cardiovascular trauma.

Animals↗
PubMed1988

Lower-extremity venous thrombosis: comparison of venography, impedance plethysmography, and intravenous manometry.

This study was undertaken to compare impedance plethysmography with lower-extremity venography and venous manometry in the diagnosis of acute deep venous thrombosis (DVT) of the lower extremity. Ninety-six extremities were studied. In this population, in which the prevalence of acute DVT was 43.8%, plethysmography had a sensitivity of 86.8% and a specificity of 72.0%. The predictive value of abnormal findings at plethysmography was 70.2%, and the predictive value of normal findings at plethysmography was 87.8%. Venous manometry was performed successfully in 89 extremities. A statistically significant difference was shown in the mean intravenous pressure between patients with and without acute DVT. However, there was considerable overlap between the two populations, limiting the predictive value of impedance plethysmography in any given patient.

Adult↗
PubMed1988

Spermatic vein embolization with hot contrast material: fertility results.

Spermatic venography with hot contrast material embolization was undertaken in 81 patients with varicoceles and infertility. Long-term follow-up information was available in 91% of the patients, and there was an overall conception rate of 40.5%. Embolization with hot contrast material was easily performed without special embolization devices and proved to be a safe and effective technique.

Adolescent↗
PubMed1988

Urinary obstruction in renal transplants: diagnosis by antegrade pyelography and results of percutaneous treatment.

We reviewed our experience with 51 renal transplants to evaluate the accuracy of antegrade pyelography as compared with that of sonography and nuclear renography in the diagnosis of transplant obstruction. Also, the results of percutaneous treatment were analyzed in 44 of these patients. Obstruction was clinically suspected in all of the patients (increased serum creatinine levels and decreased urine output). Antegrade pyelography showed obstruction in 44 (86%) of the 51 patients, and nephrostomy drainage catheters were inserted. Sonography showed pyelocaliectasis in all 49 cases in which it was performed; in 42, the pyelocaliectasis was due to obstruction (14% false-positive rate). Nuclear renography showed obstruction in only six (18%) of 33 cases in which it was performed; all six cases proved to be obstructed (0% false-positive rate and 82% false-negative rate). Twenty-two (50%) of the 44 patients treated with nephrostomy drainage were managed successfully without surgical intervention; seven of these 22 required balloon dilation of ureteric strictures in addition to catheter decompression of the collecting system. The average duration of catheterization required for successful percutaneous treatment was 35 days. This experience suggests that antegrade pyelography has a definite role in the workup of patients suspected of having renal transplant obstruction. The percutaneous access permits successful catheter drainage. Compared with antegrade pyelography, sonography is reasonably accurate in determining the presence of urinary obstruction, although false-positive diagnoses are found in a substantial number of patients. Nuclear renography is not, however, a useful indicator of obstruction owing to its high false-negative rate. Percutaneous treatment of urinary obstruction in transplantation patients proves successful in approximately 50% of cases.

Humans↗
PubMed1988

Urine leaks after renal transplantation: value of percutaneous pyelography and drainage for diagnosis and treatment.

We reviewed our experience with 12 renal transplant patients who had urine leaks to compare the accuracies of sonography and nuclear renography with that of antegrade pyelography in establishing the diagnosis. The leak was proved by surgery in 11 of the 12 cases. We also determined the role of diverting percutaneous nephrostomy drainage in the treatment of such leaks. The diagnosis was established by sonography in eight (67%) of the 12 patients. Nuclear renography, performed in nine patients, showed decreased renal function but showed the leak in only three (33%) of the nine cases. Antegrade pyelography, performed in all 12 patients, showed leakage in 10 (83%). In the other two patients, follow-up nephrostograms done within 24 hr showed leaks near the ureterovesical anastomotic site. Seven of 11 patients who were managed with a combination of percutaneous nephrostomy drainage and surgical reconstruction were treated successfully (i.e., a functioning graft was retained); however, only one patient was managed successfully by percutaneous methods alone. Antegrade pyelography is more accurate than sonography and nuclear renography in the detection of urine leakage after renal transplantation. However, percutaneous nephrostomy drainage appears useful only as an adjunct to surgery for treatment of this complication.

Adolescent↗
PubMed1987

Comparison of exercise-positive with recovery-positive treadmill graded exercise tests.

A treadmill exercise test response may become positive because a diagnostic electrocardiographic ST-segment shift occurred during exercise, or, less often, because it occurred only during the recovery period after exercise had been completed. Factors that may be related to these 2 different responses in subjects enrolled in the Program of Surgical Control of Hyperlipidemia were investigated. No differences were found with regard to age, sex, level or location of Minnesota electrocardiographic Q-QS codes, number of narrowed coronary arteries, presence of collateral coronary artery circulation, ejection fraction, number of abnormally moving left ventricular wall segments, heart rate, systolic and diastolic blood pressure, double product, total exercise time, exercise-induced angina, or maximally achieved exercise heart rate or double product. Thus, the same significance should be attributed to a recovery-positive as to an exercise-positive treadmill test, and electrocardiographic, hemodynamic and angiocardiographic variables do not distinguish between subjects who exhibit these 2 different responses.

Adult↗
PubMed1987

Limited usefulness of carbon dioxide as a contrast agent for cholangiography.

Carbon dioxide (CO2) was unsuccessfully used as a biliary contrast agent in 9 of 10 patients undergoing percutaneous transhepatic cholangiography prior to biliary drainage. The technique involved hand injection of 10-20 cc CO2 through the Chiba needle in an attempt to fill preferentially the anterior biliary radicals. Although CO2 remains a useful agent in many instances, particularly for percutaneous nephrostomy, its usefulness in the biliary tract is severely limited.

Carbon Dioxide↗
PubMed1987

Percutaneous transhepatic biliary endoscopic procedures.

Two cases are presented to demonstrate the acceptability of the percutaneous route for performing endoscopic procedures in the biliary tree. They involved debridement of an atypical villoglandular polyp and ultrasonic lithotripsy of intrahepatic stones. Both cases serve to introduce percutaneous biliary endoscopy as a viable alternative for diagnosis and therapy in selected cases.

Adult↗