In vivo thrombogenicity of intravascular ultrasound imaging catheters.

This study evaluates the frequency and significance of thrombus formation on the surface of intravascular ultrasound (US) imaging catheters. The investigation includes 63 consecutive patients who underwent 32 arterial and 38 venous intravascular procedures. At the end of the imaging procedure the US findings were observed during withdrawal of the catheter into the introducer sheath. Thrombus formation was demonstrated in 5 (7%). The largest thrombus fragments had a cross-sectional dimension of 2.2 x 1.0 mm. There was a significant correlation between the incidence of thrombus formation and the occurrence of malign neoplastic disease. No relation was found between the frequency of thrombus formation and the duration of the imaging procedure or the type of US catheter. It is concluded that the thrombogenicity of intravascular US imaging devices is not higher than that of conventional angiographic catheters. The observed "pull-out" thrombi were small and it is unlikely that they could have any clinical significance.

Catheter malfunction and thrombus formation on double-lumen hemodialysis catheters: an intravascular ultrasonographic study.

Intravascular ultrasound imaging (IVUS) is a new method that permits in vivo visualization of central venous catheters with hitherto unknown image resolution. It provides information not only about thrombus formation, but also about catheter movement, catheter malposition, and vessel wall injuries. In the present investigation the method was applied to evaluate the frequency of thrombus formation on double-lumen hemodialysis catheters and its significance for catheter malfunction. In 14 patients who had a double-lumen hemodialysis catheter for temporary or long-term vascular access, IVUS of the catheter and the mediastinal vein stems was performed. Mean indwelling duration at the time of the ultrasound investigation was 101 days (range. 3 to 730 days; median, 58 days). Four patients had catheter-related thrombotic complications: IVUS failed to detect an intracatheter thrombus in one case; a catheter thrombus and superior vena cava stenosis were found in a catheter with normal function in one case; in one case with catheter malfunction, a combined catheter-mural thrombus was found; and in the remaining case, a catheter thrombus and a mural superior vena cava thrombus were found in a patient with normal catheter function and pulmonary emboli. Thus, two of 12 patients with well-functioning catheters (16%) had thrombotic complications demonstrated by IVUS, and one of two patients with catheter malfunction had thrombus identified by IVUS. It is concluded that thrombus formation is less likely in patients without signs of catheter malfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiographic and intravascular ultrasonographic findings after endovascular stent implantation.

The study was an attempt to evaluate the benefit of intravascular ultrasound imaging (IVUS) as a supplement to follow-up angiography after endovascular stent implantation. A consecutive series of 15 patients underwent stent implantation in the peripheral or coronary arteries. Ten Palmaz stents, 3 Palmaz-Schatz stents and 2 Wallstents were used. After a period from 1 to 6 months (mean 3.2 months) follow-up angiography was performed. In 12 cases the angiography was combined with IVUS of the stent and the adjacent vessel segments. In one case IVUS failed due to the tortuous course of the vessel, in another case the stent was occluded, and in one case IVUS was considered too hazardous. In stents of diameter > or = 5 mm, ultrasound (US) did not reveal more information concerning vessel and stent diameter, stent stenosis and intraluminal surface contact than angiography alone. Smaller stents were insufficiently visualized by conventional radiologic methods. In small stents only IVUS permitted an exact stent identification and differentiation between stent stenosis and stenosis of the native vessel. At US imaging artifacts, caused by the highly reflectant metallic stent struts, interfered with the native vessel wall and partly obscured its structural details.

Iodixanol in cardioangiography. A double-blind parallel comparison between iodixanol 320 mg I/ml and ioxaglate 320 mg I/ml.

Iodixanol (Visipaque) 320 mg I/ml, a non-ionic, dimeric, isotonic contrast medium, was compared to ioxaglate (Hexabrix) 320 mg I/ml in cardioangiography. One hundred and two patients with normal renal function were included in the study. The objectives were to evaluate safety, tolerability, radiographic efficacy and effects on renal function. Adverse events, discomfort, vital signs, clinical chemistry parameters, diagnostic information and radiographic density were recorded. Both contrast media had minor effects on the renal function parameters monitored. The patients who received iodixanol experienced fewer adverse events, significantly less discomfort and had a lower increase in heart rate than did the patients in the ioxaglate group. The radiographic efficacy was good in both groups. Iodixanol 320 mg I/ml is safe and effective for use in cardioangiography.

Angiographic findings of silent ischaemia following aortocoronary bypass surgery.

Silent ischaemia, defined as ST-depression > or = 1 mm without chest pain, was found on exercise testing in 22 (10.7%) of 206 patients who underwent aortocoronary bypass surgery in the period from March 1983 to November 1985. Exercise testing was performed 4.9 (range 3.6-6.7) years after operation on an electrically braked bicycle. Sixteen of the 22 patients were free from chest pain, while the remaining six had slight to moderate angina pectoris on exercise. Coronary angiography was performed in 21 patients with silent ischaemia; one of the 22 patients died before this investigation. Some 13 patients had one or more occluded grafts, one a new stenosis in a native vessel and five incomplete myocardial revascularization. For the remaining two patients, no aetiology for the ischaemia was found, and revascularization appeared to be complete. Before surgery, 13 patients had three-vessel disease, six two-vessel disease and three one-vessel disease. At follow-up, two patients had three-vessel disease, ten two-vessel disease and seven one-vessel disease. The value of identifying patients with silent ischaemia after aortocoronary bypass surgery with regard to life expectancy and quality is controversial. Subsets of patients, namely, those with main-stem stenosis and three-vessel disease, may benefit from secondary operation. Identification of these patients may therefore be of clinical importance.

Digital dipyridamole stress echocardiography in silent ischemia after coronary artery bypass grafting and/or after healing of acute myocardial infarction.

This study evaluates dipyridamole stress echocardiography in silent ischemia. Fourteen patients with previous coronary artery bypass grafting (group A) and 16 patients with healed myocardial infarction (group B) were studied. All had > or = 1 mm ST depression without chest pain during bicycle exercise testing. Left ventricular wall motion was analyzed using a computerized display of digital systolic cineloops with a high frame rate. Test results were compared with coronary angiography. Dipyridamole echocardiography accurately identified patients with significant coronary artery stenosis in both groups (3 of 4 in group A, 11 of 14 in group B). Retrograde flow to the occluded native artery was associated with positive results on dipyridamole testing in 6 of 7 patients in group A and all 3 in group B. Sensitivity, specificity and diagnostic accuracy for detecting significant coronary stenosis or occlusions with retrograde flow was 78, 100 and 83%, respectively. Patients with angiographic multivessel disease had a significantly larger increase in wall motion score index during dipyridamole stress than patients with 0- or 1-vessel disease, 0.18 +/- 0.11 versus 0.05 +/- 0.18 (p < 0.05). Two patients developed symptomatic bradycardia and hypotension during dipyridamole infusion. It is concluded that dipyridamole echocardiography accurately identifies myocardial regions with restricted coronary flow. Stress echocardiography is a valuable tool for assessing coronary flow in silent ischemia.

Intravascular ultrasonography. Normal and pathologic findings in the great veins.

The intravascular ultrasonographic findings in normal and diseased veins after transfemoral catheterization of 25 patients are presented. The iliac veins, the inferior and superior vena cava, the renal veins, the right atrium, both brachiocephalic veins, and the right internal jugular vein were studied. In 4 cases valves or valve-like structures were observed. Anatomic variants such as spurs and webs were seen in 3 and mural thrombi or postthrombotic wall changes in 4 patients. In one case a sphincter-like ostium venae cavae was observed. In 2 patients thin filaments within the right atrium, most likely a Chiari net, were seen. Two patients had an abnormal, stratified "artery-like" vessel wall structure. This new imaging modality has several potential applicabilities in the veins and may contribute new information about anatomy and function of the venous system. It provides cross-sectional in vivo visualization and the demonstration of motility of small intraluminal structures which cannot be revealed by traditional diagnostic methods. Because of the wide range of anatomic variation in the venous system, knowledge of its normal intravascular ultrasonographic appearance is a prerequisite for further clinical investigations.

Intravascular ultrasonographic assessment of thrombus formation on central venous catheters.

In vitro experiments were performed in order to investigate the appearance of different types of central venous catheters at intravascular ultrasonography. The experiments were repeated with artificially produced thrombi which were made adherent to the catheter wall. All thrombi larger than 1 mm could be identified. In a clinical study including 12 patients who had a central venous catheter, transfemoral intravascular ultrasonography was performed. The catheters had been in place for an average period of 54 days (range 1-360 days). In 3 patients a catheter thrombus, mural thrombus, or occlusive vein thrombosis was found. In 2 of these patients the catheter was occluded, in the 3rd patient it was malpositioned into the contralateral brachiocephalic vein. There were no complications following the ultrasonographic procedures. Mean catheterization time was 7.5 min (range 3-20 min). The advantages of this new method compared with conventional phlebographic studies and its impact on further clinical investigations are discussed.

Intravascular ultrasonographic appearance of angiographically normal arteries related to age and the occurrence of vascular disease.

In 22 individuals (mean age 52 years) the ultrasonographic images of arteries defined as normal by arteriography were studied and related to the age and medical history of the patients. The series was divided into 2 groups: patients with clinical manifestation of atherosclerosis and patients without a history of arterial disease. The study included 6 young patients (mean age 14 years) referred for angiographic documentation of abolished intracranial circulation. A typical 3-layered appearance of the arterial wall was found in young healthy individuals as well as in adult and elderly subjects. There was no difference in the ultrasonographic appearance of muscular and elastic arteries. In patients with extensive obstructive atherosclerosis affecting other parts of the arterial tree, a segment of the iliac artery can have the same appearance as seen in young healthy individuals. There are indications that severe hypertension can result in a thickening of the middle low-echogenic layer of the arterial wall. In patients with chronic renal insufficiency, small calcifications in the middle layer were a typical finding.

Factors influencing return to work after aortocoronary bypass surgery.

Factors influencing the effect on employment status were investigated in 250 patients (males: females 224:26) who underwent coronary artery bypass surgery between March 1983 and November 1985. The median age at operation was 57.9 (range 36.6-69.4) years and the median follow-up time 32 (19-52) months. Preoperatively 149 patients (59.6%) were receiving sick pay or disability pension because of their heart disease. Only 64 (25.6%) were gainfully employed, in contrast to 97 (38.8%) at follow-up. Of those who were working at the time of operation, all but eight returned to work postoperatively. At follow-up 183 (80.3%) were free from symptoms or much improved, with degree of improvement somewhat greater in those who were working postoperatively. The period of sick leave and the preoperative waiting time were significantly shorter for patients who were working postoperatively than for those who were awarded disability pension. Age, previous myocardial infarction, duration of preoperative angina and type of work were also found to influence postoperative employment status.

[Ambulatory coronary angiography. Organization--patient safety--economic benefits]. / Poliklinisk koronar angiografi. Organisasjon--pasientsikkerhet--økonomisk gevinst.

916 (63%) of 1,452 coronary angiographies performed at the University Hospital in Trondheim from 1988 to 1990 were done policlinically. The study shows that coronary angiography can be carried out safely on an outpatient basis, and that more than 50% of all patients admitted for a coronary angiography can be examined in this way.

[Magnetic tomography in pulmonary vein abnormalities]. / Magnettomografi ved lungeveneanomalier.

Until recently, invasive angiographic procedures were necessary to verify the diagnosis of anomalous pulmonary venous drainage. Because of their location outside the "acoustic window" these anomalies are unsuitable for echocardiographic examination. Two cases are reported where the diagnosis was confirmed by magnetic resonance tomography (MRT). This method allows an accurate, non-invasive assessment of these structures.

MR imaging of apical hypertrophic cardiomyopathy with left ventricular endomyocardial calcification.

A rare case of apical hypertrophic cardiomyopathy with massive left ventricular endomyocardial calcification was studied with MR. The extent of the hypertrophy was clearly demonstrated, enabling accurate estimations of myocardial mass and volumes. Furthermore, an apical calcification was found and its volume estimated. In this case, MR gave the same information that was available by echocardiography, CT, and cardiac catheterization without the disadvantages of these methods.

Early postoperative weight-bearing and muscle activity in patients who have a fracture of the ankle.

Fifty-six patients who had a displaced fracture of the ankle necessitating surgical fixation were randomly assigned to one of three postoperative treatment regimens: no plaster cast or weight-bearing, and active exercises of the ankle; a non-weight-bearing plaster cast; or a plaster walking cast for the first six postoperative weeks. At follow-up with a duration of as much as two years, there were no consistent differences in the clinical results between the three groups. The time lost from work and the proportion of excellent and good clinical results were also uninfluenced by the postoperative regimen. No adverse effects could be detected as a result of the patient's having walked before the syndesmosis screw had been removed. It was concluded that none of the three postoperative regimens has any advantage over the others in a patient who has a stable osteosynthesis of a fracture of the ankle.

[The pulmodiaphragmal ligament. An often misinterpreted normal variant]. / Ligamentum pulmodiaphragmale. En ofte feiltolket normalvariant.

In some cases the pulmonary ligament extends caudally to the diaphragm, where it blends with the parietal pleura. This anatomical variant is named the pulmodiafragmal ligament. In chest X-ray it gives rise to spikes and unsharp areas in the central part of the diaphragm in the lateral view. The article describes the pulmodiafragmal ligament and its significance by the interpretation of chest X-ray in normal and pathologic states.

Selective cooling of the brain in reindeer.

Cineangiographic examination of reindeer exposed to local (hypothalamic) or general heating and cooling revealed that the angular oculi veins are constricted during cold stress but dilated during heat stress. Moreover, during heat stress a segment of the facial vein appeared to be occluded, causing the cold venous return from the nasal mucosa to be routed directly to the cavernous sinus for selective cooling of the brain. Histological examination of the vasoactive segment of the facial vein showed unusually thick longitudinal and circular layers of smooth muscle cells. Obstruction of angular oculi blood flow by clamping of the veins in the heat-stressed animal resulted in an immediate rise in brain temperature. When reindeer under heat stress shift from closed- to open-mouth panting, only the expiratory phase of the respiratory cycle takes place through the mouth, whereas inspiration through the nose is continued. In this way, cooling of the nasal mucosa and, hence, cooling of the brain, is maintained.

[Contrast medium reaction to iohexol (Omnipaque) with monocyte activation demonstrated in vivo]. / Kontrastmittelzwischenfall mit Iohexol (Omnipaque) mit in vivo nachgewiesener Monozytenaktivierung.

A contrast reaction to the intravenous injection of the non-ionic contrast medium iohexol (Omnipaque) is reported. The symptoms developed several hours after the injection and at first were not recognised as being due to the contrast. The reaction could be reproduced under controlled conditions and was associated with a significant rise in thromboplastin synthesis in circulating monocytes, a sign of marked cellular activation.