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At least 613 records · Page 34Linked to original sources
PubMed1994

Sensitivity and prognostic value of early CT in occlusion of the middle cerebral artery trunk.

PURPOSE: To investigate the incidence and prognostic value of local brain swelling, the extent of parenchymal hypodensity, and the hyperdense middle cerebral artery sign as shown by CT within the first 5 hours after the onset of symptoms in patients with angiographically proved middle cerebral artery trunk occlusions. METHODS: Fifty-three patients were studied prospectively with CT 46 to 292 minutes (median, 120; mean, 134 +/- 59) after symptom onset and scored clinically at admission and 4 weeks later. All patients were treated with recombinant tissue plasminogen activator (30 to 100 mg). RESULTS: Early CT showed parenchymal hypodensity in 43 patients (81%), local brain swelling in 20 patients (38%), and hyperdensity of the middle cerebral artery trunk in 25 patients (47%). Hypodensity covering more than 50% of the middle cerebral artery territory had an 85%, local brain swelling a 70%, and the hyperdense middle cerebral artery sign a 32% positive predictive value for fatal clinical outcome. Specificity of these findings for fatal outcome was 94%, 83%, and 51%, respectively, and sensitivity was 61%, 78% and 44%, respectively. CONCLUSIONS: Early CT in acute middle cerebral artery trunk occlusion is highly predictive for fatal clinical outcome if there is extended hypodensity or local brain swelling despite aggressive therapeutic attempts such as thrombolysis or decompressive surgery.

Adult↗
PubMed1994

Therapeutic potential of potassium channel activators in coronary heart disease.

Potassium channel activators have the ability to open potassium channels in a variety of cells. Since most of their effects are antagonized by antidiabetic sulfonylureas, the ATP-sensitive potassium channel is their likely target. Opening of potassium channels leads to hyperpolarization of the surface membrane with consequent closure of voltage-dependent ion channels and reduction of free intracellular calcium ions. Currently available potassium channel activators, including aprikalim, bimakalim, cromakalim, emakalim, nicorandil, pinacidil etc., display a high affinity for potassium channels of vascular smooth muscle. Vasodilation and a reduction in systemic vascular resistance are their prominent pharmacological effects. Coronary and cerebral arteries are highly sensitive to potassium channel activator-induced dilation. Apart from treatment of hypertension, potassium channel activators appear to have therapeutic potential in coronary heart disease. They reduce cardiac afterload, increase native and collateral coronary blood flow and reduce the size of experimental myocardial infarcts. This last effort cannot be satisfactorily explained entirely by haemodynamic or coronary vascular actions of potassium channel activators and a cardioprotective effect is postulated. For these drugs ischaemia-induced and activator-induced opening of cardiac ATP-sensitive potassium channels appear to work in concert. Nicorandil combines the pharmacological properties of an organic nitrate with those of potassium channel activators. Experimental and clinical results characterize nicorandil as a unique and promising drug for the treatment of coronary heart disease.

Animals↗
PubMed1982

Serial thallium-201 myocardial imaging after dipyridamole infusion: diagnostic utility in detecting coronary stenoses and relationship to regional wall motion.

After a 4-minute i.v. dipyridamole infusion, 0.14 mg/kg/min, serial thallium-201 scans were obtained in 60 patients undergoing cardiac catheterization. Forty patients had significant (greater than or equal to 50% stenosis) coronary artery disease (CAD), and 20 patients had normal coronary arteries or trivial lesions. The images were graded qualitatively for thallium activity by three observers. Sensitivity was 93% (37 of 40) and specificity was 80% (16 of 20). The sensitivity and specificity of the thallium-201 study were not affected by the extent of CAD, the presence of Q waves, or propranolol therapy. Twenty-seven of 37 patients who had initial defects (73%) had complete thallium redistribution of one or more defects. Patient-by-patient analysis using a regression model of all patients showed that the fate of a segmental thallium defect predicted abnormal wall motion by angiography better than ECG Q waves. The presence of propranolol therapy or collaterals did not significantly affect the thallium redistribution results. We conclude that qualitative interpretation by multiple observers of thallium images after dipyridamole infusion is a highly sensitive and specific test for CAD. After dipyridamole, as with exercise stress, the extent of thallium redistribution is related to the degree of myocardial wall motion abnormality.

Adult↗
PubMed1993

An unrelayed projection of jaw-muscle spindle afferents to the cerebellum.

Jaw-muscle spindle afferents were physiologically characterized and stained with horseradish peroxidase. Two types of afferent responses were observed during jaw-muscle stretches; one group showed considerable dynamic sensitivity indicative of primary muscle spindle afferents while the other showed little dynamic responsiveness indicative of secondary spindle afferents. Axon collaterals from both types were observed coursing within the ipsilateral superior cerebellar peduncle, indicating that some jaw-muscle spindle afferents project directly to the cerebellum without relay.

Afferent Pathways↗
PubMed1995

[Magnitude contrast angiography in peripheral arterial occlusive disease of the lower extremities].

PURPOSE: To assess the clinical value of magnitude contrast angiography in arteriosclerosis of the lower limb. MATERIAL AND METHODS: 187 examinations were done in 105 patients with arteriosclerotic lesions of the femoropopliteal vessels. The MRA results were compared to DSA and conventional angiography. 36 patients were investigated before and after angioplasty. RESULTS: Occlusions were detected correctly in all cases. In mild and moderate stenoses there was 90% agreement. High-grade stenoses may simulate occlusions. All interruptions of the signal with a length of 1 to 10 mm have to be read as high-grade stenoses (MRA sensitivity was 0.96 and specificity 0.94). In patients with low cardiac output MRA may be advantageous in comparison to DSA: collaterals and vessels distal to occlusions were visualized better in MRA. Axial scans show morphology of stenoses and occlusions and influenced the choice of treatment in 6 cases. In 3 cases, thrombotic material and calcified plaque were distinguished. After angioplasty vessel wall lesions such as dissection of the intima or compressed plaque inside the vessel wall were well visualized. Agreement was 92% with MRA as opposed to lesser values with DSA.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Thoracic collateral venous channels: normal and pathologic CT findings.

Opacification of thoracic collateral venous channels (CVC) on chest CT is considered a useful sign of superior vena cava (SVC) obstruction, although its lack of specificity has occasionally been emphasized. We compared the degree of opacification of six various thoracic CVC in a group of 36 patients with SVC syndrome and in a control group of 50 patients; a dynamic incremental CT technique with bolus injection was used. Opacification of at least one CVC is inaccurate for the diagnosis of SVC obstruction, with a false-positive and false-negative rate of 34 and 31%, respectively. Only the opacification of the subcutaneous anterior channel provides a good specificity (96%), significantly higher (p less than 0.05) than that observed for the posterior collateral channels. In patients in whom the clinical records and other direct CT signs of vena cava obstruction are doubtful or absent, opacification of a subcutaneous anterior channel on chest CT should lead to a suspicion of obstruction of the SVC and cavography should be performed.

Adult↗
PubMed1998

Stroke risk factors and development of collateral flow in carotid occlusive disease.

BACKGROUND AND PURPOSE: Blood flow through collateral vessels compensates for reduced blood flow through stenotic or occluded extracranial carotid arteries. Previous studies have shown that extent of collateral flow influences likelihood of stroke and its outcome. Here we analyzed the relationship between stroke risk factors (hypertension, coronary artery disease, diabetes mellitus, tobacco smoking and hypercholesterolemia) and number of patent intracranial collaterals detected by transcranial Doppler ultrasonography. SUBJECTS AND METHODS: We studied 182 patients with various degrees of angiography proven unilateral stenosis of the internal carotid artery. Contribution of the anterior and posterior communicating arteries to the perfusion of the cerebral hemisphere on the side of the stenosis or occlusion was evaluated by a series of compression tests performed during continuous insonation of the middle cerebral artery. The number of detected collateral vessels was correlated with analyzed stroke risk factors. RESULTS: Subjects with stenosis more than 75% or occlusion of the internal carotid artery had a higher frequency of two major intracranial collateral vessels (P< or =0.01 and P< or =0.001, respectively). Hypertensive patients with stenosis more than 75% or total carotid occlusion were more likely to have only a single collateral vessel than patients without hypertension (P< or =0.01 and P< or =0.05, respectively). Other risk factors did not influence the patency of preformed collateral vessels. CONCLUSIONS: Hypertension hindered the development of preformed intracranial collateral vessels in our patients with carotid occlusive disease.

Aged↗
PubMed2007

Medial collateral ligament complex of the ankle: MR appearance in asymptomatic subjects.

PURPOSE: To prospectively characterize the spin-echo magnetic resonance (MR) imaging appearance of the medial collateral ligament (MCL) complex of the ankle in asymptomatic volunteers. MATERIALS AND METHODS: The study was approved by institutional review board. Informed consent was obtained. MR images in 56 asymptomatic subjects (29 women, 27 men; mean age, 40.7 years; range, 23-60 years) were analyzed by two musculoskeletal radiologists. Visibility and signal intensity characteristics were analyzed for deep (anterior and posterior tibiotalar ligaments [TTLs]) and superficial (tibionavicular ligament [TNL], tibiospring ligament [TSL], and tibiocalcaneal ligament [TCL]) components of the MCL complex. Thickness of ligaments was compared between sexes (Mann-Whitney U test). Associations between age and variables of signal intensity characteristics and morphology were evaluated with Kruskal-Wallis test. RESULTS: Anterior and posterior TTLs, TNL, TSL, and TCL were visible in 31 (55%), 56 (100%), 31 (55%), 56 (100%), and 49 (88%) subjects, respectively. On T1-weighted images, anterior and posterior TTLs, TNL, TSL, and TCL were more commonly of intermediate signal intensity than hypointense (77%, 100%, 93%, 50%, and 73% of subjects, respectively); on T2-weighted images, they were commonly hypointense (55%, 52%, 42%, 75%, and 78% of subjects, respectively). On T2-weighted images, posterior TTL had a striated appearance that was significantly associated with age (P = .004) in 89% of subjects: In subjects younger than 45 years, this striated appearance was present. On T1-weighted images, striation was present in 48% of subjects. Striation was uncommon in remaining ligaments. Mean thickness and range were 1.5 mm and 1-4 mm (anterior TTL), 8.2 mm and 6-11 mm (posterior TTL), 1.6 mm and 1-2 mm (TNL), 2.0 mm and 1-4 mm (TSL), and 1.2 mm and 1-3 mm (TCL). TNL (P = .001) and TSL (P = .003) were significantly thicker in men than in women. CONCLUSION: In asymptomatic volunteers, posterior TTL and TSL were always visible, but anterior TTL and TNL are only seen in approximately half of subjects. Posterior TTL has a typically striated appearance.

Adult↗
PubMed1991

Evaluation of the patient with stable angina following coronary artery bypass surgery.

Bypass graft stenosis and occlusion are relatively common events, occurring eventually in the majority of patients who survive beyond 5 years after coronary artery bypass graft surgery. These processes, in combination with progressive native coronary artery disease, lead to recurrent angina and an increased need for medication in most patients late after surgery. Patients with unstable ischemic symptoms generally should proceed directly to coronary arteriography, whereas patients with stable angina may be candidates for noninvasive testing to evaluate their risk and the extent of myocardial jeopardy. If the initial revascularization procedure is successful, preoperative thallium 201 imaging abnormalities should be reversed. Persistent abnormalities beyond 6 months after revascularization indicate incomplete revascularization or perioperative infarction. Defects noted in the immediate postoperative period may be areas of myocardial stunning or hibernation, which can require up to 6 months to reverse. If chest pain recurs after revascularization, a normal thallium 201 perfusion pattern indicates that the symptom is probably not ischemic in nature. Thallium 201 perfusion abnormalities may precede symptoms by several months and may be the only indication of significant myocardial ischemia in patients with silent ischemia. Advanced tomographic imaging techniques, such as single photon emission computed tomography (SPECT), should theoretically improve disease detection and localization following revascularization. Practically speaking, only the left anterior descending coronary bed is well evaluated by these tomographic imaging techniques. The sensitivity and specificity of SPECT imaging for evaluation of posterior circulation abnormalities remains unacceptably low. Complexities of competitive flow and collateralization that may exist in the postoperative period make it difficult to relate perfusion abnormalities to a specific graft stenosis. However, tomographic perfusion imaging may provide useful correlative information on the functional impact of bypass graft stenoses in patients with recurrent angina who have undergone coronary angiography and in whom the angiographic indications for repeat surgery or angioplasty are not compelling. Newer tomographic and metabolic imaging techniques such as CT, NMRI, and PET remain unproven as diagnostic tests for the evaluation of unselected patient populations presenting with recurrent angina following revascularization surgery.

Angina Pectoris↗
PubMedDate not supplied

Dural sinus occlusion: evaluation with phase-sensitive gradient-echo MR imaging.

The purpose of this study was to evaluate the usefulness of limited-flip-angle, phase-sensitive velocity imaging with gradient-recalled-echo (VIGRE) MR when combined with spin-echo MR in the diagnosis of dural sinus thrombosis. The VIGRE sequence consists of a rapid single-slice acquisition, 50/15/2 (TR/TE/excitations), and 30 degrees flip angle. At each slice position, a total of four images were reconstructed; these consisted of one magnitude image and three images sensitive to proton motion in each orthogonal direction. The flow direction and flow velocity (cm/sec) were obtained from each of the phase images, and results were correlated with data obtained from a phantom experiment. In normal controls, dural sinus velocities ranged from a mean of 9.9 to 14.4 cm/sec for the transverse and superior sagittal sinuses, respectively. Three patients with proved dural sinus occlusion were studied with spin-echo images at 1.5 T. Three-dimensional time-of-flight MR angiography was also performed in one patient. The presence of dural sinus occlusion was determined by the lack of flow void on the spin-echo images, the absence of phase shift on the VIGRE study, and the presence of retrograde flow on the phase image in the sinus proximal to the occluded segment. Time-of-flight angiography overestimated the extent of the thrombosis caused by spin saturation. Follow-up VIGRE studies detected the formation of collateral flow in one patient and recanalization with the establishment of normal antegrade sinus flow in the other. We conclude that phase-sensitive MR imaging is helpful in establishing the diagnosis and extent of dural sinus occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Availability and limitations of thallium-201 myocardial SPECT quantitative analysis: assessment as daily routine procedure for ischemic heart disease.

To determine the availability and limitations of the detection of ischemic lesions by stress thallium-201 myocardial SPECT as the daily routine procedure, we compared and evaluated the detectability of the quantitative analysis (%uptake and washout rate (WR)) and visual evaluation in 104 patients with effort angina and 17 normal subjects. Visual evaluation combined with WR analysis resulted in significantly higher sensitivity (88.0%) but lower specificity (60.2%) than the other methods. The sensitivity by visual evaluation was quite low in multivessel disease (MVD), and in the regions supplied by mild coronary stenosis or by the left circumflex artery. These were markedly improved by combining visual evaluation and WR analysis, but sensitivity in the MVD group was unsatisfactory even with this analytic method in comparison with the single vessel disease group. One of the causes of low sensitivity in the MVD group might be the "true negative": No induction of the ischemia in the regions of milder stenosis, or the regions supplied by the collateral coronary flow. We therefore conclude that the combination of visual evaluation as a qualitative analysis and WR analysis as a quantitative analysis, is the most useful daily routine procedure as a screening test for detecting ischemia.

Aged↗
PubMed1976

Pharmacoangiographic manipulation of renal collateral blood flow.

Vasodilatory or vasoconstrictive renal pharmacoangiography was applied in investigating the significance of 50 renal artery stenoses. The technique involves comparison of selective magnification renal arteriograms before and after intra-arterial injection of epinephrine or acetylcholine, seeking changes in direction of flow in potential collateral routes. The drug injected depended upon the hemodynamic conditions during control arteriography. Final determination of significance depended on response to surgery in most patients, and renin levels in a few. Vasoconstrictive angiography was determinate in 18/26 (69%) of significant stenoses and correctly identified hemodynamic significance in each. Other angiographic signs of collateral circulation were present in seven of the other eight significant stenoses studied with the vasoconstrictive method. Vasodilatory pharmacoangiography was determinate in 20 arteries, and correctly evaluated each of nine significant and 11 insignificant lesions. Pharmacoangiography is a moderately sensitive and completely specific angiographic method for evaluating the hemodynamic significance of renal artery stenoses.

Angiography↗
PubMed2006

A comparison of magnetic resonance angiography with conventional angiography in the diagnosis of tetralogy of Fallot.

AIMS: Our purpose was to assess the value of magnetic resonance angiography as a non-invasive alternative to catheterization in the evaluation of patients with tetralogy of Fallot, including those with pulmonary atresia. METHODS AND RESULTS: We evaluated prospectively, using magnetic resonance angiography, 30 patients, aged from 1 to 18 years, 15 with tetralogy of Fallot and pulmonary stenosis, and 15 with pulmonary atresia. The studies obtained using magnetic resonance provided adequate visualization of the aorta, and provided excellent imaging of the pulmonary trunk and its right and left branches. Compared with catheterization, magnetic resonance had 100 percent sensitivity, specificity and accuracy for defining the presence or absence of the pulmonary arteries. Magnetic resonance also had 93.9 percent sensitivity, 98.2 percent specificity, and 96.7 percent accuracy for detection of stenosis or hypoplasia of the pulmonary arteries. We detected 25 major aortopulmonary collateral arteries with magnetic resonance, but only 22 with conventional angiography. There was complete agreement between the two methods in detecting patency of the arterial duct in 6 patients, and of Blalock-Taussig shunts in 12 patients. CONCLUSION: Magnetic resonance angiography is a useful tool in the evaluation of patients with tetralogy of Fallot. It can be considered a non-invasive alternative to cardiac catheterization in the evaluation of the pulmonary vascular anatomy.

Adolescent↗
PubMed1994

Intracranial vertebrobasilar system: MR angiography.

PURPOSE: To determine the reliability of magnetic resonance (MR) angiography in depicting normal vascular anatomy and its usefulness in detecting vascular disease compared with those of digital subtraction angiography (DSA). MATERIALS AND METHODS: Sixty patients with symptoms referable to disease of the vertebrobasilar system were examined with MR angiography and DSA. RESULTS: In patients with normal DSA results, all vertebral arteries (VAs) and basilar arteries (BAs) were also visualized with MR angiography. MR angiography demonstrated 117 of 120 superior cerebellar arteries and 80 of 90 posterior inferior cerebellar arteries but only 30 of 58 anterior inferior cerebellar arteries. MR angiography demonstrated disease of the VAs and BAs with 100% sensitivity. Stenoses were differentiated from occlusions in all cases. However, the degree of stenosis was overestimated in 63% of patients. In six patients with occlusive disease, collateral flow was correctly analyzed with selective saturation. CONCLUSION: Despite its limitations, MR angiography is a clinically important noninvasive technique for screening patients for macroangiopathy of the posterior arterial supply to the brain.

Adolescent↗
PubMed1987

Collateral sprouting in skin and sensory recovery after nerve injury in man.

Two different modes of cutaneous sensory reinnervation are thought to be engaged following nerve injury: regenerative growth of the injured nerve and 'collateral sprouting' of neighboring intact nerves. Although both processes are well known from experimental preparations, there is little unequivocal documentation of collateral sprouting in human skin. We report here on 5 patients in whom at least partial recovery of sensation in the hand following traumatic or surgical nerve section was apparently based on collateral sprouting from nerves that had not themselves been injured. Two types of evidence are brought. In three of the cases a totally anesthetic region of skin at a distance from the site of injury was shown to recover sensitivity long before regenerating nerve fibers could have arrived, given the known rates of fiber outgrowth. In the remaining two cases, nerve blocks using local anesthetics were used to establish that the reinnervated skin was served by a nerve other than the injured one. Thus, collateral sprouting appears to contribute to cutaneous sensory recovery in man as well as in animals.

Adult↗
PubMed2005

Transthoracic Doppler echocardiography as a noninvasive tool to assess coronary artery stenoses--a comparison with quantitative coronary angiography.

We prospectively tested the diagnostic accuracy of Doppler transthoracic echocardiography in detection of coronary artery stenoses throughout the main coronary arterial tree. In all, 84 patients referred for diagnostic quantitative coronary angiography were studied. Coronary artery stenosis was identified with color Doppler as local spot of turbulence, and local flow velocity was measured using pulsed wave Doppler. Angiography showed significant stenoses (diameter reduction > 50%) in 33 patients. An abnormal maximal-to-prestenotic blood flow velocity ratio greater than 2.0 in subtotal stenoses, or the detection of collateral blood flow in the absence of normal antegrade flow in the case of total occlusion (N = 6), resulted in overall sensitivity of 82% and specificity of 92%. The sensitivity and specificity were, respectively, 73% and 92% for left anterior descending coronary artery, 63% and 96% for right coronary artery, and 38% and 99% for left circumflex coronary artery stenoses. Transthoracic echocardiography is a promising noninvasive technique to diagnose significant coronary artery stenoses.

Coronary Angiography↗
PubMed1987

Determinants of improved left ventricular function after thrombolytic therapy in acute myocardial infarction.

Many studies have been performed to evaluate the efficacy of thrombolytic therapy in achieving reperfusion, salvaging myocardium and enhancing survival. This review discusses the concordance between the results of these clinical studies and the observations made in experimental animals of the effect of reperfusion on the recovery of left ventricular function. The evaluation of functional recovery is affected by the timing of the measurement and the sensitivity of the method for detecting regional abnormalities. In addition, the underlying coronary anatomy also determines outcome, so that infarct location, collateral circulation and the degree of coronary obstruction merit consideration. Two factors are of paramount importance in determining the amount of myocardium salvaged, the recovery of left ventricular function and the reduction in mortality. These factors are: the time delay until reperfusion is achieved and the adequacy of the coronary reflow. The close agreement between studies measuring the effect of reperfusion on left ventricular function and studies with mortality as the end point provides indirect evidence that enhancement of survival in patients treated with thrombolytic agents is mediated by recovery of ventricular function.

Angioplasty, Balloon↗