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Biomedical subjects

K Amplatz

Publications and source records attributed to K Amplatz.

At least 19 recordsLinked to original sources
PubMed1992

Changes in sequential coronary arteriograms and subsequent coronary events. Surgical Control of the Hyperlipidemias (POSCH) Group.

OBJECTIVE: Assessment of the relationship between changes in sequential coronary arteriograms and subsequent clinical coronary events. DESIGN: The Program on the Surgical Control of the Hyperlipidemias, a randomized secondary atherosclerosis intervention trial, obtained coronary arteriograms at baseline, 3, 5, and 7 or 10 years of follow-up. Assessments of changes between pairs of coronary arteriograms were made by two-member panels blinded to the patients' assigned treatment and to the temporal sequence of the films. The relationship of changes between the baseline and the 3-year follow-up arteriograms and subsequent clinical coronary events was examined. SETTING: Three university hospitals and one private primary care facility. PATIENTS: A total of 838 patients, with 417 patients randomized to the control group and 421 to the intervention group. Of all patients, 695 had baseline and 3-year arteriograms. INTERVENTION: The control group received American Heart Association Phase II diet instruction and the intervention group received identical dietary instruction plus a partial ileal bypass operation. MAIN OUTCOME MEASURE: The use of arteriographic changes as a predictor of subsequent clinical coronary events. RESULTS: Changes between the baseline and the 3-year coronary arteriographic overall disease assessment were significantly associated with subsequent overall and atherosclerotic coronary heart disease mortality (P less than .01). For the combined end point of atherosclerotic coronary heart disease mortality or confirmed nonfatal myocardial infarction, a significant relationship between the overall disease assessment and subsequent clinical events was found in the control group (P less than .0001) and in the surgery group (P = .04). For this combined end point, however, the control and the surgery groups were different with respect to clinical coronary events after 3 years, stratified by the baseline to 3-year overall disease assessment (P less than .001, unadjusted; P = .06, adjusted for 3-year clinical covariates). CONCLUSIONS: Coronary arteriographic changes can be used in atherosclerosis intervention trials as a limited surrogate end point for certain clinical coronary events. This relationship is statistically compelling for overall mortality and atherosclerotic coronary heart disease mortality. For an individual patient, changes in the severity of coronary atherosclerosis seen on sequential coronary arteriograms can serve as prognostic indicators for subsequent overall or atherosclerotic coronary heart disease mortality.

Adult↗
PubMed1992

Correlation of coronary with peripheral arterial stenosis. The POSCH Group.

Although it is known that patients with peripheral arterial disease are at high risk for coronary arterial stenosis, it is not known if, conversely, coronary artery disease correlates with peripheral arterial stenosis. In the Program on Surgical Control of the Hyperlipidemias (POSCH) coronary and aortic-iliac-femoral arteriograms were systematically analyzed. POSCH is a randomised, controlled secondary intervention clinical trial of hyperlipidemic subjects, ages 30-64 years with one myocardial infarction and angiographically demonstrable coronary arterial stenosis. Of the 838 subjects enrolled in the study, 436 had diagnostic visualization of both the coronary and aortic-iliac-femoral systems. The aortic-iliac-femoral arteries were normal in 44% (194/436) of the subjects. In contrast, only 9% (37/436) of the subjects had less than 50% stenosis of all 3 coronary arteries. However, there was a positive correlation between the severity of the stenosis, if present, in the aortic-iliac-femoral arteries and that in the coronary arteries (P less than 0.001). The subjects who did exhibit aortic-iliac-femoral arterial disease were significantly older and more frequently were cigarette smokers. We conclude that subjects with coronary arterial stenosis frequently are free of peripheral arterial disease.

Adult↗
PubMed1992

Pneumothorax after lung biopsy: prevention with transpleural placement of compressed collagen foam plugs.

The effectiveness of pleural sealing with a compressed collagen foam plug in preventing the development of pneumothorax was evaluated in a prospective, comparative study of 50 patients undergoing transthoracic needle biopsies. The 4-cm-long plug was deposited through the thin-walled guidance needle at the end of the procedure in a position where it would cross both the visceral and the parietal pleura. The prevalence of postbiopsy pneumothorax was 28% (seven of 25 patients) in the control group and 8% (two of 25 patients) in the plug group. In each study group, two patients with pneumothoraces required chest tubes. Although further experience is necessary, the authors conclude that transpleural collagen foam plug placement may be an effective supplement for transthoracic needle biopsies.

Biopsy, Needle↗
PubMed1991

Positive and negative exercise test results with and without exercise-induced angina in patients with one healed myocardial infarction: analysis of baseline variables and long-term prognosis.

The prognostic implications of exercise test results with and without exercised-induced angina are not completely understood. In the Program On the Surgical Control Of the Hyperlipidemias (POSCH), 838 subjects with hyperlipidemia who had one healed myocardial infarction were studied and followed for 6 to 13 years (mean 8.6). Of the 417 control subjects, 279 had a treadmill exercise test result that was definitely positive or negative. Angina was also induced by exercise in 30% (45/150) and 8% (10/129) of those with a positive and a negative test result, respectively (p less than 0.0001). The data showed no difference between subjects with a positive or a negative test result with or without angina as regards levels of blood lipids, type of myocardial infarction (Q or non-Q wave), left ventricular function, or prognosis as defined by death, atherosclerotic coronary heart disease death, or myocardial infarction.

Angina Pectoris↗
PubMed1991

Incomplete opening of LGM (Vena Tech) filters inserted via the transjugular approach.

Over a 12-month period, 216 LGM vena caval filters were placed in 216 patients at four institutions. The transjugular approach was used in 31 of 216 insertions (14%); 185 of 216 filters (86%) were inserted via the femoral route. Incomplete opening of filters was encountered in 13 of 31 transjugular insertions (41%) and none of 185 transfemoral insertions. Delayed spontaneous filter opening occurred in three of 12 cases (25%) of incomplete opening (in which follow-up was available) at 5 minutes, 4 days, and 2 months after insertion. One filter opened completely after catheter manipulations. Several mechanisms explaining this complication are proposed. In its present form, the LGM filter should not be inserted via the jugular route. Since the filtering capabilities of the incompletely opened LGM device have been shown to be diminished in vitro, it may be advisable to place a second filter cephalad to an incompletely opened LGM filter.

Equipment Failure↗
PubMed1991

Spermatic vein occlusion with hot contrast material: angiographic results.

Spermatic vein occlusion by means of selective injection of boiling contrast material into the spermatic vein was attempted in 175 men with symptomatic varicoceles or infertility. Seventy-six patients (43%) returned for follow-up venography. Of 115 veins injected, 96 (83%) were totally occluded on the follow-up venogram obtained at 6 weeks to 2 years after injection. In the latter portion of the study, the technique was changed slightly, with injection of larger volumes of hot contrast material, resulting in a 91% occlusion rate. Each vein that was found patent on the follow-up venogram (19 of 115 [16%]) was assessed radiographically, and results were categorized as grade 1, a complete failure in which there was no change from the presclerotherapy appearance (nine of 19 [47%]); grade 2, a failure in which the treated vein was smaller but patent (five of 19 [26%]); or grade 3, a failure in which the treated vein was occluded with newly developed collateral vessels (five of 19 [26%]). The pretreatment size of the spermatic vein and the quantity of hot contrast material injected were both statistically significant factors in the treatment outcome.

Adolescent↗
PubMed1991

Thrombectomy with the transluminal endarterectomy catheter (TEC) system: experimental study and case report.

The transluminal endarterectomy catheter (TEC) system was employed as a percutaneous rotational mechanical thrombectomy device in 1-week-old thrombi in five dogs (five thrombosed polytetrafluoroethylene grafts and four thrombosed native superficial femoral arteries). Luminal patency was restored in all vessels with no angiographic evidence of significant distal embolization. The TEC catheter was also successfully used for recanalization of the superior vena cava in a patient with superior vena cava syndrome.

Animals↗
PubMed1991

Urokinase-mediated thrombolysis: a dose-response relationship in cats. Work in progress.

A cat model was developed to study thrombolytic agents. The infrarenal aorta was surgically exposed, all side branches were ligated, and both ends of the segment were occluded. After preformed clot was injected into the segment, proximal flow was restored and a distal stenosis was created. Urokinase was infused at rates varying from 4,000 to 250,000 U/h. Amount of remaining clot was quantified every 15 minutes with cine angiography. Pre- and postinfusion measurements of prothrombin time, partial thromboplastin time, thrombin time, and levels of fibrinogen and fibrin degradation products were obtained. A graph of thrombolysis rate versus infusion rate was obtained yielding maximal thrombolytic activity at 126,000 U/h and 90% of maximal activity at an infusion rate of 70,000 U/h. Levels of fibrin degradation products did not change. Prothrombin, partial thromboplastin, and thrombin times increased with increasing infusion rates, leveling off at 100,000 U/h, while fibrinogen levels decreased, with a plateau at 50,000 U/h.

Animals↗
PubMed1991

Angiogenesis after hepatic arterial occlusion in liver transplant patients.

The authors describe 10 liver transplant recipients who developed occlusion of the hepatic artery or aortic conduit. Since all potential collateral arterial supply to the transplant is severed at hepatectomy, hepatic artery occlusion is usually a catastrophic event that necessitates repeat transplantation. Four patients died within 8 weeks of transplantation. The remaining six developed spontaneous arterial liver revascularization. This phenomenon is believed to be an example of neovascularization through angiogenesis. Radiologic studies, particularly duplex sonography and angiography, were helpful in the evaluation of transplant vascular integrity. The tissues of the omentum and the mesentery have known angiogenic ability. The authors postulate that in transplantation techniques in which these tissues are placed close to the transplanted liver (eg, Roux-en-Y choledochojejunostomy), the omental and mesenteric tissues may be the source of neovascularity.

Adult↗
PubMed1991

Nonselective and semiselective catheters for renal artery evaluation: experimental study.

Abdominal aortography is widely used for evaluation of potential renal donors and for patients with renal failure or hypertension in whom a renal artery ostial or polar branch stenosis is suspected. It would be desirable to use a catheter that consistently enables good bilateral renal artery and polar branch visualization without opacification of overlying mesenteric vessels. Existing and newly designed catheters were compared to determine the optimal design necessary for these studies. An in vitro model of the abdominal aorta and its branches was made, and dye dilution densitometry was employed for quantitative evaluation. Semiselective catheters demonstrated significantly increased renal artery opacification with decreased mesenteric opacification in this in vitro model.

Aorta, Abdominal↗
PubMed1991

Nitinol gooseneck snare for removal of foreign bodies: experimental study and clinical evaluation.

The authors describe their use of a new right-angle snare made of nickel-titanium (nitinol) cable for retrieval of foreign bodies and iatrogenically placed devices. The snare loop is at right angles to the cable and comes in five sizes (5, 10, 15, 25, and 35 mm); its radiographic visualization is enhanced by gold-plated tungsten coils. This snare was used to retrieve wire and catheter fragments introduced into the thoracic vasculature of four dogs. Eleven of 13 attempts were successful. Three attempts to retrieve intravascular foreign bodies were successful in two patients; in one of these patients, a 10-mm snare was used to remove a fractured end of a ventriculoatrial shunt tube from the left pulmonary artery. In three other patients, four ureteral stents were successfully removed under fluoroscopic guidance. All retrievals were performed through a vascular sheath and with standard techniques and angiographic equipment. No complications were seen in any of the patients or dogs.

Alloys↗
PubMed1991

Clot-trapper device for transjugular thrombectomy from the inferior vena cava.

The clot-trapper device for transjugular thrombectomy was used in 10 dogs with acute thrombosis and two dogs with chronic thrombosis. In eight of these animals, the clots were trapped with the clot-trapper device, then a mechanical thrombectomy device was used to destroy the clots. In 10 animals, including eight with in vitro thrombi and two with in situ thrombi, thrombi were efficiently trapped with the clot-trapper device. In two animals, pulmonary embolism occurred because of a discrepancy between the diameter of the inferior vena cava and the diameter of the bag opening. After increasing the size of the loop to match the diameter of the inferior vena cava, trapping of all thrombi was possible in both experiments (acute and chronic thrombosis). The clot-trapper device, in conjunction with an embolectomy balloon catheter and/or a mechanical thrombectomy device, facilitates the removal of thrombi from the inferior vena cava and iliac veins.

Animals↗
PubMed1991

Thermal ablation of the gallbladder.

Gallbladder ablation by means of injection of hot contrast medium was attempted in 13 dogs. Room temperature contrast medium was injected into the gallbladders of two additional dogs (controls). After midline laparotomy was performed to expose the gallbladder, temperature probes were placed in the liver adjacent to the gallbladder, and on the surface and in the lumen of the gallbladder. A 7-F catheter with multiple side holes was placed into the gallbladder. The cystic duct was clamped during the procedure. After injection of boiling contrast medium, the mean temperature in the gallbladder lumen was 80 degrees C; in the adjacent liver, 43.5 degrees C; and on the gallbladder surface, 45.8 degrees C. After the procedure, the cystic duct was unclamped, temperature probes and catheter were removed, and the laparotomy was closed in standard fashion. In the hot contrast medium group, one dog each was sacrificed at 2, 4, 8, and 12 weeks, and at 6 months. Six animals were sacrificed at 1 year. The gallbladder was completely ablated in 11 of 13 animals in the hot contrast medium group. One dog was sacrificed at 8 days because of bile leakage, and another was sacrificed at 17 days because of gallbladder rupture. The two control animals were sacrificed at 12 and 13 weeks, and their gallbladders were normal at that time.

Animals↗
PubMed1991

1990 ARRS Executive Council Award. Intravascular sonography in the detection of arteriosclerosis and evaluation of vascular interventional procedures.

The purpose of this study was to evaluate the use of intravascular sonography for the detection of arteriosclerosis and to determine the effects of vascular interventional procedures on the arterial wall. A catheter-based 20-MHz transducer was used. Forty patients were studied. Twelve had clinical evidence of peripheral vascular disease, 13 were healthy renal donors, and 15 underwent vascular interventional procedures. The aorta and the ipsilateral iliac artery were examined in real time under fluoroscopic guidance and the results were compared with angiography. Sonography in eight of the 13 renal donors showed arterial wall abnormalities in the absence of angiographic evidence of disease. Sonography of the 15 patients after angioplasty or atherectomy demonstrated plaque fractures, intramural dissections, or atherectomy grooves. Our experience suggests that intravascular sonography is of value in reducing the use of angiography to monitor progress or complications of vascular interventional procedures.

Adult↗
PubMed1991

[Intravascular echography in interventional vascular radiology].

Intravascular US studies were performed with a 20 MHz rotating transducer mounted on a long flexible shaft in 14 patients undergoing interventional vascular procedures--i.e. percutaneous transluminal angioplasty (PTA), atherectomy with a Simpson device, and Palmaz stent placement. Intravascular US was used immediately before the procedure to assess the lesion characteristics and during and after the procedure to verify its results. In PTA, intravascular US clearly shows the fracture of the plaque, its separation from the medial layer, and the total longitudinal extension of the intimal flaps. Palmaz stents are clearly shown and their correct positioning on the arterial wall is therefore precisely evaluated. After atherectomy, intravascular US shows the changes in wall thickness and identifies the areas where more tissue needs to be removed. Intravascular US appears to be a very promising technique for monitoring and directing revascularization procedures by helping select the correct interventional procedure. The initial limitation of use of intravascular ultrasound catheters to straight arterial segments has been resolved by the development of over-the-wire catheters. Further technical development and clinical research are needed.

Adult↗
PubMed1990

A useful projection for demonstrating the bifurcation of the pulmonary artery.

The demonstration of the pulmonary bifurcation is important in order to exclude pulmonary branch stenoses. The origin of the right and left pulmonary arteries can be demonstrated in the anteroposterior plane if cranial angulation is used. Depending on the course of the left pulmonary artery, the origin of the left pulmonary artery may not be seen in spite of the maximal cranial angulation. On the lateral plane without tube angulation the origin left pulmonary artery is commonly superimposed on the origin of the right pulmonary artery. If maximum caudal angulation is added to the steep left anterior oblique view, not only the left, but also the origin of the right pulmonary artery can be seen.

Constriction, Pathologic↗
PubMed1990

Estimation of left ventricular ejection fraction with healed myocardial infarction by multiple regression analysis of electrocardiographic Minnesota Q-QS codes. POSCH Group.

The cardiac damage caused by a myocardial infarction may be evidenced by abnormal electrocardiographic Q-QS complexes (i.e., Minnesota Q-QS codes) and by impairment of left ventricular function. It has been shown that the level of significance of the Q-QS codes is highly correlated with the extent of left ventricular impairment. This study was directed to quantitating this relationship in subjects with a healed myocardial infarction and expressing it mathematically. Using multiple linear regression analysis, a coefficient value was obtained corresponding to the level of significance of each Q-QS code located in each electrocardiographic cardiac area. The left ventricular ejection fraction was estimated by subtracting the coefficient of the most significant code present in each cardiac area from the constant, which was calculated to be the ejection fraction in the absence of any Q-QS code. The results were reproducible, and there was a good correlation between the estimated and measured ejection fraction.

Adult↗