Intravascular ultrasound imaging of Guenther vena caval filters.
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Biomedical subjects
Publications and source records attributed to J Slany.
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BACKGROUND AND PURPOSE: The aim of this study is to report on the use of transcranial Doppler ultrasonography as a noninvasive diagnostic monitoring tool during local intra-arterial thrombolysis in a patient with acute embolic occlusion of the middle cerebral artery. CASE DESCRIPTION: We describe a 41-year-old woman with mitral valve stenosis suffering from embolism of the middle cerebral artery. Local thrombolysis was performed with tissue plasminogen activator at a dosage of 0.05 mg/kg/hr. Progress of the thrombolysis was monitored by transcranial Doppler. The steps of recanalization could be ascertained by transcranial ultrasound showing a hemodynamically relevant residual stenosis after the first 120 minutes and complete patency of the M1 segment of the middle cerebral artery 180 minutes later. One branch of the middle cerebral artery still showed a filling defect. CONCLUSIONS: Our report demonstrates the potential usefulness of transcranial Doppler monitoring during thrombolysis of a proximal occlusion of the middle cerebral artery for guiding the treatment by assessing the reperfusion of the obstructed artery.
BACKGROUND AND PURPOSE: The aim of this trial was to evaluate the effectiveness of extracranial-intracranial bypass with respect to vasomotor reactivity in patients with internal carotid artery occlusions and absent vasomotor reactivity, comparing them with a control group treated conservatively. METHODS: To test vasomotor reactivity in 104 patients with unilateral occlusion of the internal carotid artery, we measured blood flow velocity in the middle cerebral artery by transcranial Doppler sonography both at rest and after injection of acetazolamide. Among the 39 patients who failed to show increased mean blood flow velocity after the acetazolamide test distal to an occluded internal carotid artery by greater than or equal to 10%, 14 subjects subsequently underwent extracranial-intracranial bypass surgery (group A) and 14 age- and sex-matched subjects in whom no such procedure was done composed the control group (group B). Follow-up examinations were performed 3-6 months postoperatively and in the control group 3-6 months after initial examination. RESULTS: Baseline values of the mean blood flow velocity at rest on the affected side were reduced in both groups compared with the contralateral healthy side (group A, 46.0 +/- 15.1 cm/sec; group B, 48.1 +/- 16.7 cm/sec) and revealed only a marginal increase after acetazolamide. The contralateral side showed a normal blood flow velocity at rest and an adequate response to acetazolamide in both groups. On the follow-up examination group A demonstrated a normalized vasodilatory capacity. Blood flow velocity increased significantly after acetazolamide from 41.9 +/- 13.1 cm/sec to 53.5 +/- 16.0 cm/sec (p less than 0.002). In group B, the compromised vasomotor reactivity remained unchanged. CONCLUSIONS: Our results demonstrate that transcranial Doppler sonography together with the acetazolamide test can identify subjects with reduced vasomotor reactivity distal to an occluded internal carotid artery, who may improve hemodynamically by an extracranial-intracranial bypass.
Transcranial Doppler sonography (TCD) enables measurement of blood flow velocities in the basal intracerebral vessels. The most important applications of TCD in the ICU are the diagnosis and monitoring of vasospasms caused by subarachnoid hemorrhage after rupture of an aneurysm. Further indications are the non invasive diagnosis of critical decreases of cerebral perfusion pressure, the evaluation of brain death and the monitoring of thrombolysis of occlusions of the middle cerebral artery. TCD lends itself as a valuable non invasive bedside-monitoring tool, which enables continuous or intermittent monitoring of intracerebral hemodynamics without strain for the patients. Disadvantages to be mentioned are the dependence of experienced examiners and the long lasting training phase required to achieve the requisite experience.
In patients with non-valvular atrial fibrillation one must differentiate between those without a clinically suspected embolic event and those who have sustained embolism or stroke of uncertain origin. All of the latter should undergo echocardiography as part of a comprehensive search for a possible source of embolism. A positive finding will enhance the probability that the ischaemic event was indeed caused by a cardiac embolus. It must be kept in mind, especially in stroke patients, that long-term anticoagulation will expose many of them to a far higher risk of haemorrhage [26] due to multimorbidity, propensity to repeated falls and difficulties in compliance than it did to the carefully selected cohorts of the recent warfarin studies. Whenever transthoracic echocardiography (TTE) fails to disclose an unequivocal cardiac source of embolism, transesophageal echocardiography (TEE) should be performed. In persons with atrial fibrillation but no history of systemic embolisation the only rationale for performing echocardiography is to rule out heart disease in clinically suspected lone atrial fibrillation. For the rest of this group TEE remains an investigative tool.
Critically ill patients with intracerebral hemorrhage require immediate treatment in an intensive care unit. In the acute phase of the disease the patients are endangered from increased intracerebral pressure, respiratory disorders (aspiration!) and hypertension. An adequate intensive care management consisting of sedation, analgesia, intubation and mechanical ventilation, correct body positioning and treatment of hypertension is of decisive importance for the prognosis of these patients. The aim of this report is to discuss the most important therapeutic strategies and arising problems in the course of intracerebral hemorrhage.
A previously healthy man, aged 33 years, suddenly developed a hemiparesis and right facial paresis, as well as anisocoria and motor aphasia, preceded by recurrent attacks of dizziness. On admission he was somnolent. A flow murmur was heard over both carotid arteries; the blood pressure was 160/80 mm Hg. Cerebral computed tomography demonstrated multiple hypodense areas in the area supplied by several cerebral arteries, and marked cerebral oedema. Angiography of the aortic arch and the supra-aortic branches showed an occlusion of the left common carotid artery and a stenosis of the brachiocephalic trunk. The cerebral oedema, caused by ischaemia, did not respond to treatment. The patient died on the fourth hospital day from brainstem "strangulation". At autopsy syphilitic mesaortitis with characteristic lymphoplasmacellular endangiitis of the vasa vasorum of the aortic arch was demonstrated as the cause of the "aortic arch syndrome". Serology confirmed the diagnosis of an untreated tertiary syphilis. (VDRL titre 1:256; TPHA reactive; IgM-SPHA titre 1:64). Although a very rare cause, a late stage of syphilis should be considered in the differential diagnosis of cerebrovascular lesions in youngish patients.
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The diagnostic accuracy of the dipyridamole test in provoking coronary insufficiency was investigated in 79 patients with chest pain and the results were compared with the findings on angiography and exercise electrocardiogram. 58 patients had documented severe coronary artery stenosis, 21 had patent coronary vessels (cardiomyopathy 8, aortic stenosis 1, ectopic origin of coronary artery 1, normal 11). Anginal pain after dipyridamole was a non-specific finding. Approximately half the subjects in whom coronary insufficiency would be expected according to the coronary angiographic and ventriculographic findings evidenced ischaemic ST-segment depression after dipyridamole, which was comparable to the number of positive exercise electrocardiograms. In 23 patients, most of whom had shown an inadequate frequency response during the initial exercise test, ergometry was repeated after the administration of dipyridamole. This resulted in an increase in ischaemic ECG response from 26 to 70%. It is concluded that a stress test combining dipyridamole and submaximum exercise increases the incidence of ischaemic ST-segment depression in comparison with ergometry alone. Anginal pain without ST-segment depression proved to be without diagnostic value.
Contrast echocardiograms during normal quiet respiration and during the Valsalva maneuver were performed in 15 patients with atrial septal defect (ASD) by injecting saline solution into an antecubital vein. Contrast shunting (the appearance of contrast echoes in the left heart) was observed not only in four patients with severe pulmonary hypertension (group 2), but also in 11 patients with uncomplicated ASD (group 1). Contrast shunting was prominent in all group 2 patients. In group 1, contrast shunting was sometimes subtle and difficult to recognize, but at other times was very obvious and similar to the findings in group 2. Contrast shunting was generally more pronounced during the Valsalva maneuver than during normal respiration, although there were exceptions. The amount of contrast appearing in the left heart did not correlate with the size of the defect. Small right-to-left shunts which are clinically insignificant but detectable by contrast echocardiography are present, or can be provoked by the Valsalva maneuver, in most patients with ASD. Contrast echocardiography is a useful, noninvasive method to detect interatrial communication, even in acyanotic patients.
Sixty-six consecutive patients without left ventricular volume overload, significant arrhythmia or significant pericardial effusion were examined by M-mode echocardiography immediately before diagnostic left- and right-heart catheterization. Using various echocardiographic measurements, left ventricular stroke volume (SV) was calculated according to eight different echocardiographic formulas (SVE) that have been proposed previously. At catheterization SV was also determined by thermodilution (SVT) and by single-plane left ventricular cineangiography in the right anterior oblique projection (SVA). When comparing SVE with SVT, the four formulas developed to calculate mitral or aortic flow failed (r = 0.10 to 0.54). As expected, poor correlations (r = 0.22 to 0.47) were also found when formulas used to calculate ventricular volumes from the ventricular diameter or SV from the change in diameter (left ventricular formulas) were used in coronary patients with grossly asymmetrical ventricular contraction patterns. When the use of the left ventricular formulas was confined to patients with symmetrical or almost symmetrical contraction, two formulas yielded favorable correlations of r = 0.84, SEE = 12.7 ml and r = 0.86, SEE = 12.2 ml, respectively. These correlations were comparable to the correlation between our two invasive reference techniques (r = 0.81; SEE = 12.2 ml). The comparison between SVE and SVA confirmed the results of the thermodilution study, though the correlations were generally weaker. We conclude that the formula of Teichholz et al., which was the best of all tested formulas, may be used to obtain a clinically useful estimate of SV in patients in whom symmetrical or almost symmetrical left ventricular contraction can be anticipated.
The echocardiogram of a patient presenting with a systolic ejection murmur and ECG evidence of left ventricular hypertrophy revealed asymmetric septal hypertrophy but no abnormal systolic anterior motion of the mitral valve as in IHSS. Her pulmonary echo disclosed small A waves, partial valve closure in early systole and coarse systolic fluttering. This motion pattern--which is similar to that of patients with infundibular pulmonary stenosis and which resembles the aortic valve motion pattern in discrete subaortic stenosis--led us to the diagnosis of hypertrophic cardiomyopathy with subpulmonic obstruction, which was later confirmed by cardiac catheterization.
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Myocardial scarring and coronary insufficiency give rise to regional changes in left ventricular function, often leading to generalized left ventricular dysfunction during physical activity only. The main purpose of this study was to evaluate the relations between left ventricular function determined by ECG and measurements of pulmonary artery pressure during exercise and the severity of coronary artery disease. Simultaneous measurements in the pulmonary artery and in the left ventricle in 76 patients revealed that the enddiastolic pulmonary pressure (PAEDP) was lower than the enddiastolic pressure in the left ventricle (LVEDP) by a mean value of 10.5 mm Hg in the presence of ventricular dysfunction. This difference was smaller in congestive heart failure than in cases of acute myocardial ischaemia. Correlation coefficients of mean pulmonary wedge pressure (PCm), PAEDP, mean pulmonary pressure (PAPm), and LVEDP were 0.90, 0.86, and 0.81, respectively, thus allowing only an approximate estimate of the left ventricular filling pressure. In 150 angiographically documented cases of coronary heart disease, haemodynamic measurements were performed during stepwise-increased, symptom-limited supine exercise on a bicycle ergometer. All patients limited at 25 watts had either triple vessel disease or stenosis of the trunk of the left coronary artery or of the proximal section of the left anterior descending artery (RIVA). In comparison with subjects with single vessel disease, patients with triple vessel involvement tolerated only a smaller exercise load and reached higher values of PAEDP (30.4 +/- 9.0 versus 24.0 +/- 7.7 mm Hg, p less than 0.001). Analysis of data of patients with a single coronary stenosis showed the exercise-PAEDP to be largely independent of the myocardial condition, but to depend upon the location of the stenosis, the highest pressure values being observed with stenoses of the main left coronary artery or the proximal segment of the RIVA. Based on these findings a simple coronary score system was delineated to determine the severity of the disease, taking into account the location of an obstruction, in particular, and, to a lesser amount, the degree of the stenosis and the type of coronary artery distribution. The score yielded essentially better correlations to work load and filling pressures during exercise than did the number of obstructed vessels. The regression line of the PAEDP versus the coronary score was flatter in patients with angiographically documented collaterals than in cases without, indicating the functional significance of these vessels. In patients with stenoses confined to the arteries supplying infarcted areas and, consequently, without signs of ischaemia during exercise a close relation was obtained between the left ventricular ejection fraction (EF) and the maximum PAEDP, best expressed by a third order regression equation (r = 0.79), p less than 0.001, SEE +/- 6.1). A PAEDP exceeding 25 mm Hg is, thus, a reliable sign of an EF of less than 40%...
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