Showing papers on "Stenosis published in 1985"

Expandable intraluminal graft: a preliminary study. Work in progress.

Abstract: To overcome the problem of recurrence of stenosis after vascular balloon dilatations, we developed an expandable, intraluminal graft that allows dilatation of the lesion and simultaneous placement of a supportive endoprosthesis to prevent recoil of the arterial wall. The graft is made of continuous, woven, stainless steel wire. The resulting tubular mesh has a wall thickness of 200-450 micron and 80% open surface. The grafts, mounted on angioplasty catheters, are introduced through 8-12-F Teflon sheaths. Eleven grafts of 6, 8, and 10 mm in diameter by 20 mm long were placed in the aorta, common carotid, superior mesenteric, iliac, and renal arteries of dogs. Six grafts showed no stenosis in follow-up studies of up to 8 weeks. Two grafts had moderate stenosis as a result of neointimal hyperplasia. Two partial and one complete graft thrombosis occurred in nonheparinized animals in which the graft outflow was restricted. Anticoagulant was not used on a long-term basis. Light and electron microscopy studies s...

Effect of Gastric Acid on the Pathogenesis of Subglottic Stenosis

Abstract: A case of subglottic stenosis, recalcitrant to conventional therapy, was associated with asymptomatic aspiration of gastric acid into the larynx. Once the reflux was controlled by use of an antacid regimen and an H2 blocker, the subglottic stenosis resolved and the patient could be decannulated. This case led to the use of an experimental canine model of subglottic stenosis to examine gastric acid as a pathogenic factor in the development of subglottic stenosis. In control animals, mucosal lesions healed without development of stenosis. In experimental animals with mucosal lesions painted with gastric acid, subglottic stenosis developed. When perichondrium and cartilage were violated and gastric acid applied, stenosis was even more severe and developed more rapidly.

Lumbar spinal stenosis. Clinical features, diagnostic procedures, and results of surgical treatment in 68 patients.

Abstract: Our experience with 68 patients with strictly defined, myelographically proven, surgically confirmed lumbar spinal stenosis seen over a 30-month period was reviewed. Pseudoclaudication was the commonest symptom (94%) and was described by patients as pain (93%), numbness (63%), or weakness (43%). Symptoms were frequently bilateral (68%) and generally relieved by flexing the lumbosacral spine. Neurologic abnormalities were found in a minority of patients and were usually mild. Electromyography showed one or more lumbosacral radiculopathies in 34 of 37 patients examined. Radiographic evidence of degenerative disk or joint disease was found in 63 patients. All patients had stenosis on myelography, with narrowing at L2, L3, and L4 being the commonest; 30% had multi-level stenosis. Two of ten computed tomograms were normal. Surgery was extensive; 72% of patients had three or more laminae removed. At a mean of 4 years after surgery, 84% of patients reported that surgery had yielded good to excellent results.

Natural history of asymptomatic carotid plaque

Abstract: • In April 1981, a total of 297 carotid arteries were examined prospectively. All patients were asymptomatic and were referred to the peripheral vascular laboratory at Good Samaritan Medical Center, Phoenix, for real-time B-mode ultrasonography. A measurement of luminal area stenosis was determined to be either greater or less than 75%. In addition, the ultrasound echo pattern was used to classify plaque as either calcified, dense, or soft. If, for any reason, the patient or physician felt that carotid endarterectomy should be performed, the patient was dropped from the study. In addition, the use of antiplatelet medication or anticoagulants constituted disqualification. Three groups of patients were observed for three years or until symptoms became apparent. Patients in all three groups with stenosis greater than 75% at the time of initial study were at greater risk than their peers without significant narrowing; however, even those patients with less than 75% stenosis were at greater risk if the associated plaque was less organized, ie, soft. A definite trend toward higher risk is seen in plaques of lower density. Only 10% of those patients with calcified plaque and a significantly stenotic vessel have developed symptoms. In contrast, only three patients of the original 42 with soft plaque and a tight stenosis are still being observed. This study appears to confirm that soft plaques have a greater tendency toward subintimal hemorrhage, ulceration, or primary embolization than more well-organized plaques. (Arch Surg1985;120:1010-1012)

The pathomorphology of spinal stenosis as seen on CT scans of the lumbar spine.

Abstract: This study examines different morphologic measurements in the evaluation of patients with lumbar spinal stenosis. Preoperative CT scans from 24 patients who underwent surgery for central lumbar stenosis were analyzed. No correlation was observed between the size of the bony spinal canal and the size of the dural sac. A new measurement, the transverse area of the dural sac, is introduced. Normal values are provided. Correlation between the cross-sectional area of the dural sac and the anteroposterior diameter of the dural sac was excellent.

Spontaneous dissection of the extracranial vertebral arteries.

Abstract: Though the syndrome of carotid artery dissection is well known, "spontaneous" vertebral artery dissection is rarely recognized. We now report clinical and radiologic findings in five patients with presumed vertebral dissection, one pathologically confirmed. Mean age was 35.2 years (range 27-41). Two were men; three women. None had hypertension, vascular disease, or trauma. Headache and neck or occipital pain was prominent in all, often preceding other symptoms. Four of five patients had unilateral partial alteral medullary syndromes, in one accompanied by medial medullary signs. One patient had a cerebellar infarct. Angiography in four patients showed severe irregular stenosis of the distal extracranial vertebral artery (three bilaterally). A fifth patient with irregular stenosis above the vertebral origin had verified extensive dissection in the resected segment. No patient developed late ischemia. Repeat angiography in three showed healing. We conclude that spontaneous vertebral artery dissection, though rare, has recognizable clinical and radiologic features.

Morphology of ambulatory ST segment changes in patients with varying severity of coronary artery disease. Investigation of the frequency of nocturnal ischaemia and coronary spasm.

Abstract: The frequency and magnitude of objectively determined myocardial ischaemia during normal daily activities of patients with varying severity of coronary artery disease are unknown. Furthermore, the incidence of nocturnal resting myocardial ischaemia and frequency of coronary spasm in patients with normal coronary arteries and chest pain are also not known. One hundred consecutive patients with chest pain referred for coronary angiography were therefore investigated with exercise testing and ambulatory ST segment monitoring. Fifty two of 74 patients with significant coronary artery disease and six of 26 with no significant coronary narrowing had episodes of ST segment change during 48 hours of ambulatory monitoring. Two patients, one with normal coronary arteries and localised spasm and one with three vessel disease, had episodes of ST segment elevation, whereas all other patients had episodes of ST segment depression. The frequency, duration, and magnitude of ST segment changes were greater in patients with more severe types of coronary artery disease. Thus more than six episodes of ST segment change per day occurred in patients with two or three vessel disease or left main stem stenosis and in the only patient with coronary spasm and normal coronary arteries. Nocturnal ischaemia occurred in 15% of patients with coronary artery disease and was almost an invariable indicator of two or three vessel coronary artery disease or left main stem stenosis. Episodes of ST segment change occurred most commonly during the morning hours and least commonly during the night, in parallel with changes in basal hourly heart rates. The heart rate at the onset of ST segment change tended to be lower in patients with coronary artery disease than in those with normal coronary arteries. The duration of exercise to ST segment depression tended to be shorter in patients with more severe disease, but it could not predict patients with nocturnal myocardial ischaemia, left main stem stenosis, or coronary spasm, whereas ambulatory ST segment monitoring was able to identify most of these patients.

Factors that determine recovery of left ventricular function after thrombolysis in patients with acute myocardial infarction.

Abstract: The coronary and ventricular angiograms of 47 patients with acute myocardial infarction in whom reperfusion was achieved by intracoronary streptokinase were quantitatively analyzed to determine the factors that affect recovery of regional left ventricular function after reperfusion. Hypokinesis in the infarct region was measured by the centerline method and expressed in terms of standard deviations (SDs) from normal. Severity of coronary artery stenosis was measured quantitatively. Hypokinesis showed more significant improvement after thrombolysis in patients with minimum stenosis diameter of greater than 0.4 mm than in those with severe residual stenosis, i.e., stenosis producing a minimum diameter of 0.4 mm or less (1.0 +/- 1.3 SD/chord, n = 31, vs 0.0 +/- 0.9 SD/chord, n = 7; p less than .05). Improvement in hypokinesis was greater in patients who received thrombolytic therapy within 2 hr than in those treated later (2.1 +/- 1.1, n = 8, vs 0.7 +/- 1.0 SD/chord, n = 28; p less than .001). These results indicate that angiographic reperfusion alone may not be sufficient: reperfusion must provide adequate flow and be achieved early to salvage myocardial function.

Quantification of coronary artery stenosis in vivo

Abstract: VISUAL interpretations of coronary arteriograms are marked by such great interobserver and intraobserver variability (Bjork et al., 1975; Detre et al., 1975; Zir et al., 1976; DeRouen et al., 1977; Meyers et al., 1978) that comparison of arteriograms from different subjects, or at different times in the same subject, are of limited value for assessing severity, changes in severity, or functional significance of coronary artery stenoses. The universal use of relative percent diameter narrowing as a clinical measure of severity ignores other geometric characteristics of stenoses such as length, absolute diameter, multiple lesions in series, or eccentric narrowings which may be worse in one view, compared with another view. In vivo quantification of coronary stenosis is necessary for studying the pathogenesis, pathophysiology, and progression/regression of coronary artery disease. For example, what severity of coronary artery stenosis is necessary for altering ventricular function or metabolism? What degree of coronary artery narrowing can be detected by noninvasive methods? What are the quantitative effects of a variety of pharmacological agents on stenosis severity? Why do patients develop resting angina pectoris at one time but not at other times during equal supply-demand conditions? Is percent narrowing or absolute stenosis dimension the more important measurement? How do we quantify the shear forces on the endothelial wall at sites of arterial bending, branching, and/or narrowing which are important in the pathogenesis of cholesterol deposition, atheroma formation, and abnormal endothelial behavior, including platelet activation or release of substances causing arterial vasospasm?

Quantitative angiography of the left anterior descending coronary artery: correlations with pressure gradient and results of exercise thallium scintigraphy.

Abstract: To evaluate, during cardiac catheterization, what constitutes a physiologically significant obstruction to blood flow in the human coronary system, computer-based quantitative analysis of coronary angiograms was performed on the angiograms of 31 patients with isolated disease of the proximal left anterior descending coronary artery. The angiographic severity of stenosis was compared with the transstenotic pressure gradient measured with the dilation catheter during angioplasty and with the results of exercise thallium scintigraphy. A curvilinear relationship was found between the pressure gradient across the stenosis (normalized for the mean aortic pressure) and the residual minimal area of obstruction (after subtracting the area of the angioplasty catheter). This relationship was best fitted by the equation: normalized mean pressure gradient = a + b . log [obstruction area], r = .74. The measurements of the percent area of stenosis (cutoff 80%) and of the transstenotic pressure gradient (cutoff 0.30) obtained at rest correctly predicted the occurrence of thallium perfusion defects induced by exercise in 83% of the patients.

Early detection of restenosis after successful percutaneous transluminal coronary angioplasty by exercise-redistribution thallium scintigraphy

Abstract: The value of exercise testing and thallium scintigraphy in predicting recurrence of angina pectoris and restenosis after a primary successful transluminal coronary angioplasty (PTCA) was prospectively evaluated. In 89 patients, a symptom-limited exercise electrocardiogram (ECG) and thallium scintigraphy were performed 4 weeks after they had undergone successful PTCA. Thereafter, the patients were followed for 6.4 +/- 2.5 months (mean +/- standard deviation) or until recurrence of angina. They all underwent a repeat coronary angiography at 6 months or earlier if symptoms recurred. PTCA was considered successful if the patients had no symptoms and if the stenosis was reduced to less than 50% of the luminal diameter. Restenosis was defined as an increase of the stenosis to more than 50% luminal diameter. The ability of the thallium scintigram (presence of a reversible defect) to predict recurrence of angina was 66%, vs 38% for the exercise ECG (ST-segment depression or angina at peak workload). Restenosis was predicted in 74% of patients by thallium scintigraphy, but only in 50% of patients by the exercise ECG. Thus, thallium scintigraphy was highly predictive but the exercise ECG was not (p less than 0.005). These results suggest that restenosis had occurred to some extent already at 4 weeks after the PTCA in most patients in whom it was going to occur.

Supravalvular aortic stenosis. Clinical and pathologic observations in six patients.

Abstract: Supravalvular aortic stenosis with a mean pressure gradient of 101 mm Hg was encountered in six patients aged 1 1/2 to 12 years. Three patients had Williams syndrome. In two other patients the stenosis was familial. The angiographic/anatomic subtype of deformity was hourglass in four patients, diffuse in one, and membranous in one. Four patients are alive following successful surgical repair; the other two died without surgery. Microscopically, disorganized medial elements with fibrotic intima sometimes containing lacunae were observed in five cases; the one other had valvelike tissue only. Ultrastructurally, thick irregular elastic fibers, abundant swirling collagen, hypertrophied smooth-muscle cells, and scant ground substance characterized the medial tissue defect. Although hemodynamics during intrauterine development may predispose to localization of the stenosis to the supra-aortic valvar region, the cause for the mural dysplasia remains uncertain.

Duplex carotid sonography: criteria for stenosis, accuracy, and pitfalls.

Abstract: Both carotid bifurcations were examined in 353 patients over a 20-month interval using a combination of real-time and pulsed Doppler ultrasound (duplex scanning). Angiographic correlation was available in 72 cases. Stenosis of the internal carotid was evaluated using a Doppler input frequency of 5 MHz and a scan angle of 60 degrees. A peak frequency shift of less than 3.5 kHz was found to be a sign of less than or equal to 30% stenosis; 3.5-4 kHz with moderate turbulence suggested 31-50% stenosis, 4-8 kHz 51-90% stenosis, and greater than 8 kHz greater than 90% stenosis. Subtotal stenosis (greater than 95%) was manifested by a frequency shift of less than 8 kHz, but the waveform was totally distorted. Overall accuracy improved from 77% for the first 6 months to 87% for the last 14 months. For stenosis greater than 50%, sensitivity improved from 82% to 97% during this period. Analysis of errors and suggestions for avoiding them are presented.

Survival, myocardial infarction, and employment status in a prospective randomized study of coronary bypass surgery.

Abstract: This report from the European Prospective Randomised Study presents 8 year results on survival and 5 year results on myocardial infarction and employment status. The 768 recruited patients were all men under age 65 with mild or moderate angina, 50% or greater stenosis in at least two major coronary arteries, and a left ventricular ejection fraction of 50% or greater. One "surgical" patient was lost to follow-up immediately after randomization and is therefore excluded from the statistical analysis. Thus 394 patients allocated to surgery were compared with 373 patients allocated to medical treatment, regardless of what subsequently happened to the patients. The policy of early surgery improved survival significantly compared with the conventional medical treatment policy in the total population (89% to 80%, respectively; p = .0013) and in the subgroup with three-vessel disease (92% and 77%, respectively; p = .00015). Reclassification of vessel disease by greater than 75% instead of 50% or greater stenosis as the criterion was undertaken to facilitate comparison of these results with those of other studies, which apply 70% or greater stenosis as the criterion of significant disease. Of the 767 patients, a cohort of 711 were identified as having greater than 75% obstruction in one, two, or three vessels. A significant improvement in survival with surgery was found in the total cohort (89% and 80%, respectively; p = .0022), the subgroup with three-vessel disease (91% and 73%, respectively; p = .0044), and that with two-vessel disease in which one of the diseased vessels was the proximal segment of the left anterior descending artery (LAD) (90% and 79%, respectively; p = .013). There was no significant difference in survival between the two treatments in patients with one-vessel disease and those with two-vessel disease without proximal LAD stenosis. Four noninvasive prognostic variables were independently predictive of the effect of surgery: resting electrocardiogram (in 767 patients), ST segment response to exercise (in 656), history and physical signs of peripheral arterial disease (in 722), and age (in 767). A reduction in cardiac deaths was entirely responsible for the improved survival with surgery. The incidence of myocardial infarction in the medical group (11%) was not significantly different from that in the surgical group (15%). Repeat angiography in 71 patients showed 6% graft closure between 1 and 5 years of follow-up. Surgery did not influence the gradually increasing annual rate of retirement from work.

Cause of cerebral infarction in the carotid territory. Its relation to the size and the location of the infarct and to the underlying vascular lesion.

Abstract: Seventy-three patients with acute nonhemorrhagic stroke in the carotid territory were investigated for the cause of the stroke: middle cerebral artery (MCA) occlusion/stenosis or internal carotid artery (ICA) occlusion/stenosis; embolus from the heart and extra-cranial arteries or thrombosis. The study is prospective and consecutive comprising stroke patients below the age of 75 years, admitted in the acute state i.e. within 3 days after stroke onset. Excluded were patients with intracerebral hematoma, subarachnoid hemorrhage, vertebrobasilar stroke and patients in whom another severe disease was present. Cerebral angiography and CT-scan were performed in all patients within one and two days after admission. CT-scan was repeated 2 weeks and 6 months later. Forty percent had MCA occlusion, none had MCA stenosis, 12% had ICA occlusion, 14% had severe ICA stenosis (half of these were associated with MCA occlusion) and 41% were without significant MCA/ICA lesions. Twenty-seven percent had large infarcts with a diameter greater than 3 cm; 34% had medium-sized infarcts with a diameter between 3 and 1.5 cm; 21% had small infarcts with a diameter less than 1.5 cm; 18% had no identifiable infarct on CT-scan. MCA occlusion was responsible for 62% of the large or medium-sized infarcts. ICA occlusion or severe ICA stenosis were responsible for only 27% of the large or medium-sized infarcts. Only 11% of the patients with small or no infarct on CT-scan had significant MCA/ICA lesion.(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous balloon pulmonary valvuloplasty.

Abstract: Percutaneous pulmonary valvuloplasty was performed in 27 patients with congenital pulmonary valve stenosis. A fall in the transvalve gradient of at least 15 mm Hg occurred in 22 patients. In five there was little change in the severity of the stenosis; in three of these the pulmonary valve was dysplastic. None of the successfully treated patients had a dysplastic valve. The two other failures, early in the series, were probably due to inadequate balloon size. In one patient the procedure was performed twice, with a successful result from the second dilatation with a larger balloon. Follow up studies in a further six patients showed no evidence of restenosis in those who had been successfully treated and no late improvement in the remainder. There were no important complications. Percutaneous pulmonary valvuloplasty should be the initial treatment for congenital pulmonary valve stenosis, although when the valve is dysplastic the result is less likely to be satisfactory.

Percutaneous transluminal dilatation of the iliac artery: long-term results.

Abstract: One hundred fifty-four patients with stenosis of the iliac artery underwent percutaneous transluminal angioplasty (PTA). These patients were followed for 1-7 years. The long-term results of the PTAs were analyzed by computer, and life tables were generated for dilatations of the iliac arteries with unimpaired flow and for those with an obstruction in the outflow tract. The accumulative 7-year patency rate was 90%, which agrees with other reports. This study demonstrates that the long-term results of PTA of iliac arterial stenoses are competitive with reconstructive vascular surgery. PTA should be the treatment of choice in patients with iliac arterial stenoses.

Hemodynamic principles in the control of coronary blood flow.

Abstract: The effects of atherosclerotic epicardial stenoses on coronary vascular resistance can be understood in terms of basic principles of fluid mechanics. Resistance is directly related to the pressure drop across the stenosis and inversely related to flow. Even with a fixed anatomic stenosis, however, resistance is not fixed; it increases as flow across the stenosis increases. This exacerbates the pressure drop across the stenosis that develops as a result of flow; at high flows, large pressure drops can occur. This characteristic of flow through stenotic lesions can contribute to a “steal” phenomenon between either epicardial or intramural coronary arteries. Studies have also shown the clinical importance and influence of dynamic alterations in coronary resistance, occurring either at the large or small vessel level. In addition, compressive forces exerted by the myocardium or by elevated intraventricular pressures can increase coronary vascular resistance, and thus interfere with myocardial perfusion. All of these factors must be considered in order to obtain a comprehensive understanding of the mechanisms leading to myocardial ischemia and, therefore, to the clinical syndrome of angina pectorls.