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Biomedical subjects

J Schofer

Publications and source records attributed to J Schofer.

At least 73 records · Page 4Linked to original sources
PubMed1986

Thallium-201/technetium-99m pyrophosphate overlap in patients with acute myocardial infarction after thrombolysis: prediction of depressed wall motion despite thallium uptake.

Intracoronary thallium-201/technetium-99m pyrophosphate planar scintigraphy was performed in 60 patients with acute myocardial infarction undergoing intracoronary thrombolysis to predict salvage of myocardium immediately after thrombolysis. In eight patients a significant overlap of new thallium uptake and technetium pyrophosphate accumulation was found after thrombolysis. Intravenous planar thallium scintigraphy revealed thallium uptake in the region of overlap in all patients; circumferential profile analysis showed no difference in the thallium scintigrams before and after technetium injections. Both findings indicate that overlap is not the result of scattering of technetium into the thallium window. Emission computed tomography revealed thallium/technetium pyrophosphate uptake in identical slices and regions. Regional wall motion in the area of overlap remained depressed in all patients, in contrast to patients with similar thallium uptake without overlap. These data suggest that thallium/technetium pyrophosphate overlap reflects the close proximity of viable and necrotic myocardial cells and predicts depressed wall motion after thrombolysis.

Adult↗
PubMed1986

Advantages and applications of the centerline method for characterizing regional ventricular function.

We sought to identify theoretical advantages and applications of the centerline method for quantitative assessment of regional ventricular function. Motion was measured along 100 chords constructed perpendicular to a centerline drawn midway between the end-diastolic and end-systolic contours, and normalized for heart size. Abnormality was expressed in units of standard deviations from the mean motion in a normal reference population to indicate both the severity and significance of the wall motion abnormality. The mean abnormality averaged over 100 chords correlated highly with the area ejection fraction (r = .97). The centerline method uses a "sliding window" to measure motion where it is abnormal, because assessment of wall motion in predefined regions of the ventricular contour underestimates abnormality. From the 100 data points, the extent (% of contour) of regional abnormalities can also be determined. The severity of hypokinesis at the site of acute myocardial infarction correlated better with infarct size estimated from creatine kinase release (r = -.78) than did the ejection fraction or the circumferential extent of hypokinesis. Because the centerline method measures motion along locally determined vectors, and requires no apex, origin, coordinate system, or geometric reference figure, it can be applied to contours as dissimilar as the 60 degree left anterior oblique projection of the left ventricle and the 75 degree left anterior oblique projection of the right ventricle.

Computers↗
PubMed1986

Measurement of regional wall motion from biplane contrast ventriculograms: a comparison of the 30 degree right anterior oblique and 60 degree left anterior oblique projections in patients with acute myocardial infarction.

The value of performing biplane vs single plane analysis of regional wall motion from contrast ventriculograms was determined in 102 patients who received thrombolytic therapy and who underwent biplane ventriculography during acute myocardial infarction (n = 67), at follow-up more than 2 weeks later (n = 80), or both (n = 45). Hypokinesis in the infarct region and hyperkinesis in the noninfarct region were measured by the centerline method in the respective artery territories, which were defined from the data of 62 patients with single-vessel disease and were expressed in units of standard deviations from the mean of 32 normal subjects. Hypokinesis was more severe and extended over a longer segment of the left ventricular contour when measured in the right anterior oblique (RAO) projection in thrombosis of the left anterior descending coronary artery (LAD) but more severe and extensive in the left anterior oblique (LAO) projection in circumflex stenosis. Hyperkinesis opposite the LAD or the circumflex was greater in the LAO projection. In patients with thrombosis of the right coronary artery, wall motion abnormalities were similar in the two projections. Thus the evaluation of hypokinesis caused by acute coronary thrombosis and of the effect of therapeutic interventions in salvaging function can be adequately evaluated from single-plane 30 degree RAO ventriculograms, except in the small minority of patients with circumflex thrombosis.

Cineradiography↗
PubMed1986

[Early noninvasive detection of reperfusion and infarct by intravenous technetium 99m pyrophosphate scintigraphy following thrombolysis].

To determine whether technetium-99-pyrophosphate accumulation immediately after intravenous thrombolysis can serve as a marker of reperfusion and infarct size, 17 patients with acute myocardial infarction were studied. Immediately after thrombolysis 10 mCi of technetium-99m pyrophosphate were injected intravenously. Coronary and left ventricular angiography were then performed in all patients, revealing patent coronary arteries in 13 patients. In all patients, 0.3 and 0.5 mCi of thallium-201 were injected into the right and left coronary artery, respectively, followed by planar scintigraphy. 6 patients with patent coronary arteries and a large thallium-201 defect had massive (more than one third of the cardiac silhouette) pyrophosphate accumulation (group A), whereas 7 patients with a small or no thallium-201 defect in the presence of a patent infarct artery had either focal or no pyrophosphate accumulation (group B). In contrast, 4 patients with an occluded infarct artery showed no acute pyrophosphate uptake despite a large thallium-201 defect (group C). Emission computed tomography confirmed the planar scintigraphic data in group A patients and revealed small thallium-201 defects and focal pyrophosphate accumulation in group B patients with negative planar scintigrams. Global and regional ejection fractions in the infarct area, measured from the acute and follow-up left ventricular angiograms, were higher in group A than in group B and C patients. It is concluded that early intravenous technetium-99m pyrophosphate scintigraphy in patients with acute myocardial infarction undergoing intravenous thrombolysis may serve as an indicator of reperfusion and infarct size.

Adult↗
PubMed1985

[Time dependence of myocardial preservation after thrombolysis. Consequences for indication and procedure].

To examine whether the limitation in infarct size after effective thrombolytic therapy is time-dependent the relationship between left ventricular wall motion in the infarct region and the time interval between onset of symptoms and intracoronary streptokinase infusion was investigated. The relationship was significant: When intracoronary thrombolytic therapy was begun within 2 hours, wall motion was almost always within normal limits, whereas the probability of wall motion improvement fell to less than 50%, when treatment was begun later. As a further step a lysis procedure was examined which took account of these findings: the intravenous bolus injection of urokinase. Approximately one hour after bolus injection coronary patency could be demonstrated angiographically in 60% of the infarct patients. A clinically relevant limitation of the infarct size was found in those patients in whom lysis therapy could be begun within 2 hours. On the basis of these findings, a thrombolytic therapy seems to be indicated in all patients with acute myocardial infarction when lysis treatment can be begun within 2 hours. The intravenous urokinase therapy, by virtue of its simplicity, is an alternative to intravenous streptokinase therapy.

Angiography↗
PubMed1985

[The clonidine inhibition test: an aid in the diagnosis and postoperative therapeutic control in pheochromocytoma].

A clonidine-suppression test was carried out in 8 patients with arterial hypertension, raised urinary and plasma catecholamine levels and symptoms suggesting the presence of a pheochromocytoma. In 6 of the patients clonidine reduced the plasma catecholamine concentrations and no pathological findings were seen in the abdominal computed tomogram (CT). In 2 patients noradrenaline levels were excessively high and not lowered by clonidine; in one of these patients the plasma adrenaline concentration was also raised and this too could not be reduced with clonidine. A tumor was detectable in both patients using CT, in one case situated in the left adrenal, in the other extra-medullary. On operation both were found to be a pheochromocytoma. Peritoneal and intra-hepatic metastases were discovered during surgery in the case of the extramedullary localized tumor. The clonidine-suppression test was repeated postoperatively in both patients: it was normal in the case of the completely excised, intramedullary situated tumor but still pathological in the other. Thus the clonidine-suppression test is useful in the diagnosis and post-surgical assessment of pheochromocytoma.

Adult↗
PubMed1985

Intravenous urokinase in acute myocardial infarction.

To achieve reperfusion early, an intravenous bolus of 2 million units of urokinase was administered in 50 patients with transmural acute myocardial infarction (AMI) 1.8 +/- 2.5 hours after the onset of symptoms. Coronary angiography performed 1.1 +/- 0.6 hours after urokinase therapy revealed patent coronary arteries in 30 patients (60%), with no significant difference between those with anterior and those with inferior AMI. Reocclusion occurred in only 1 of 24 patients restudied. Failure to achieve reperfusion was not related to the degree of systemic fibrinolytic activity, which was equally high in patients who did and those who did not achieve reperfusion, as evident from serially obtained fibrinogen measurements (77 +/- 52 vs 84 +/- 24 mg/dl, difference not significant). Plasmin activity, measured serially from 15 minutes to 24 hours after urokinase in 7 patients, was maximal at 15 minutes and undetectable after 3 hours. Wall motion at the infarct site measured from contrast ventriculograms was significantly better at follow-up only in patients in whom reperfusion was achieved and who received urokinase within 2 hours after the onset of symptoms as compared with patients in whom reperfusion was not achieved (-1.2 +/- 1.4 vs -2.4 +/- 0.9 standard deviations from normal, p less than 0.05). Peak serum creatine kinase level was significantly lower in patients in whom reperfusion was achieved than in those in whom it was not or those who had rethrombosis (802 +/- 763 vs 1,973 +/- 1,071 U/liter, p less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1985

Time from onset of symptoms to thrombolytic therapy: a major determinant of myocardial salvage in patients with acute transmural infarction.

To determine whether myocardial salvage after successful intracoronary or intravenous thrombolysis is time dependent, the relation between left ventricular wall motion and the time to treatment was studied in 69 patients admitted less than 3 hours after onset of acute transmural myocardial infarction (42 patients with reperfusion by intracoronary streptokinase, 27 by intravenous urokinase). A similar significant relation between the time to treatment and the severity of regional hypokinesia at follow-up was found in the intracoronary and intravenous groups. To better define this relation, particularly during the early phase of infarction, the groups were combined. In patients in whom thrombolytic treatment was initiated within 2 hours after symptom onset, wall motion at follow-up was within 2 standard deviations of the normal mean in 82% (14 of 17 patients). If treatment was started 2 to 5 hours after symptom onset, the probability of improved wall motion decreased to 46% (24 of 52 patients, p less than 0.025). The time/wall motion relation appeared to be independent of infarct location, angiographically visible collateral vessels and the presence of subtotal coronary artery occlusion. The severity of hypokinesia at follow-up study correlated with the magnitude of peak serum creatine kinase (r = -0.71), indicating that thrombolytic therapy initiated within 2 hours after the onset of symptoms improves regional left ventricular function and reduces infarct size more than later therapy does.

Adolescent↗
PubMed1985

Scintigraphic evidence of the "no reflow" phenomenon in human beings after coronary thrombolysis.

To assess whether the absence of new thallium-201 uptake after successful intracoronary thrombolysis reflects a disturbance of myocardial cell function or lack of capillary reperfusion, dual isotope scintigraphic studies with thallium-201 and technetium-99m micro-albumin aggregates were performed in 16 patients with acute anterior myocardial infarction. Intracoronary thallium-201 and technetium-99m scintigraphy performed before intracoronary thrombolysis in 12 of the 16 patients resulted in identical thallium-201 and technetium-99m defect sizes. Immediately after intracoronary thrombolysis, thallium-201 and technetium-99m scintigraphy was repeated in 11 of the 12 patients. In 4 of the 11, the initial thallium and technetium scintigraphic defects were significantly reduced, and in 6 of the 11, they were only slightly reduced; there was no difference in the size of the residual defect as assessed with both radionuclides in all 10 of the 11 patients. In the eleventh patient, there was a significant reduction of the initial technetium-99m scintigraphic defect but no change in the size of the thallium-201 defect. In four other patients, scintigrams were obtained only after intracoronary thrombolysis; these revealed no difference in thallium-201 and technetium-99m defect size. In seven of eight patients restudied 2 to 4 weeks after intracoronary thrombolysis, thallium-201 and technetium-99m defect sizes were identical with those immediately after intracoronary thrombolysis; in the eighth patient there was no difference in thallium-201 and technetium-99m defect size, although such a difference had been present immediately after intracoronary thrombolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Scintigraphic evidence that the right ventricular myocardium tolerates ischaemia better than the left ventricular myocardium.

To study the incidence of right ventricular infarction and the effect of intracoronary thrombolysis on the ischaemic right ventricular myocardium, we performed intracoronary myocardial thallium scintigraphy in 18 patients with complete occlusion of the right coronary artery who underwent intracoronary thrombolysis. In 15 of these patients, intracoronary thallium-201 and technetium-99 m pyrophosphate scintigrams were performed simultaneously. All 18 patients had a right ventricular thallium defect before thrombolysis, and all had new thallium uptake after thrombolysis. 17 out of 18 patients had a left ventricular thallium defect before thrombolysis, but only 10 of them showed new thallium uptake after thrombolysis. 14 out of 15 patients had a left ventricular technetium-99 m pyrophosphate spot after thrombolysis and some diffuse pyrophosphate accumulation in the area of the right ventricle. In one patient pyrophosphate accumulation was found only in the area of the right ventricle. Thus, right ventricular thallium defects were detected by intracoronary thallium scintigraphy in the majority of patients with inferior acute myocardial infarction due to right coronary artery occlusion. Right ventricular thallium defects were always reversible in contrast to left ventricular thallium defects in the same patients, suggesting that right ventricular myocardium tolerates ischaemia better than left ventricular myocardium.

Adult↗
PubMed1985

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

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.

Adult↗
PubMed1985

[Ineffective use of lidocaine in preventing reperfusion arrhythmias in patients with acute myocardial infarct].

To study the efficacy of prophylactic lidocaine treatment on the genesis of ventricular tachyarrhythmias following recanalization of an occluded coronary artery, 49 patients with an acute myocardial infarction were studied. All patients underwent intracoronary thrombolysis. Patients were admitted within 3 hours of the onset of symptoms and were randomized into two groups: 23 patients received an intravenous infusion of lidocaine (2 mg/min), following an initial bolus of 200 mg, and the remaining 26 patients received no lidocaine. Reperfusion arrhythmias were documented in 16 of 20 successfully recanalized patients who received lidocaine and in 15 of 21 successfully recanalized patients without lidocaine treatment. There were no statistically significant differences between the two patient groups in the frequency of occurrence of ventricular tachycardias or ventricular fibrillation. Independent of lidocaine treatment, two types of ventricular tachycardia could be distinguished: the most frequent type 1 met the electrocardiographic criteria of tachycardia caused by enhanced automaticity, whereas the characteristics of the less frequent type 2 tachycardia suggested reentry or triggered activity as the underlying mechanism. Only type 2 ventricular tachycardias were accompanied by haemodynamic deterioration. Our results show that lidocaine, in the dosage given here, does not influence incidence or mechanisms of reperfusion tachyarrhythmias.

Angioplasty, Balloon↗
PubMed1985

[The 4 hr-washout-functional picture: a quantitative visualization of 201Tl myocardial stress kinetics and the significance of paradoxical redistribution].

Between March and August 1983, 62 patients with suspected coronary artery disease were investigated by both 201Tl myocardial scintigraphy and coronary angiography. Functional images of the 4 h-201Tl-washout were compared with conventional scintigrams of the stress and rest phases and with results of coronary angiography. Myocardial scintigraphy with 4 views was performed immediately after exercise and 3-4 h later. After interpolative background subtraction, 4 h-washout functional images were computed from each of the initial scintigrams and the corresponding delayed scintigrams. Using a special-coded colour table, the 4 h-washout could be read quantitatively from the functional image. The additional analysis of washout images increased the accuracy of myocardial 201Tl scintigraphy for the detection and localization of coronary stenoses from 42% to 69%. Sensitivity increased from 42% to 73%, definitivity from 50% to 79%. Ischemic regions appeared more obvious in the washout images, even to less experienced observers. In comparison with circumferential washout profiles the interpretation of washout images was easier because of more obvious anatomical localization. The phenomenon of "reverse redistribution" was found to be associated with a decreased 201Tl-washout in apparently "normal" regions, whereas in those regions with "reverse redistribution" the washout was normal or at least relatively high. In addition diffuse myocardial ischemia occurring in 3-vessel disease could be recognized in the 4 h-washout functional images.

Coronary Disease↗
PubMed1985

[Color-coded 2-dimensional Doppler echocardiography. Initial clinical experiences].

A new technology based on the Doppler principle for ultrasound has recently enabled the real-time visualization of cardiac blood flow by superposition of coloured flow information onto a two-dimensional echocardiogram. This study presents typical flow patterns in standard echocardiographic views, obtained from normal subjects and patients with acquired valvular or congenital heart diseases. Diagnostic possibilities and limitations of colour-coded Doppler echocardiography are discussed.

Adult↗
PubMed1984

Assessment of myocardial necrosis immediately after intracoronary thrombolysis by intracoronary injection of technetium-99m pyrophosphate.

To assess myocardial necrosis immediately after intracoronary thrombolysis, thallium-201 (TL-201) and technetium-99m pyrophosphate (Tc-99m PYP) were injected simultaneously into the coronary artery in 25 patients with acute transmural myocardial infarction. In 17 of the 25 patients, the occluded coronary artery was reopened. Minutes after the intracoronary injection of Tc-99m PYP into the reopened coronary artery a localized accumulation was seen within the area of the Tl-201 defect in all patients. Control intravenous scintigraphy, which was performed in 8 of these 17 patients 1-6 days later, and in 2 patients 18 and 42 days after infarction, revealed a Tc-99m PYP spot similar to that of the acute intracoronary Tc-99m PYP scintigram in all 10 patients. In the 8 of the 25 patients, in whom intracoronary thrombolysis failed, no localized Tc-99m PYP accumulation was seen after injection into the infarct vessel. In 5 of these patients, a control intravenous scintigram, performed 1-8 days later, resulted in a Tc-99m PYP spot in the area of the Tl-201 defect. We conclude that, in the presence of therapeutic or spontaneous reperfusion, Tc-99m PYP scintigraphy may provide a useful method of assessing myocardial necrosis during the early stage of an acute myocardial infarction.

Adult↗
PubMed1984

Intracoronary thallium 201 scintigraphy as an immediate predictor of salvaged myocardium following intracoronary lysis.

Since February of 1980, 157 patients who had had symptoms of acute myocardial infarction for less than 3 hours underwent intracoronary lysis. Forty-six patients required early aorta-coronary revascularization. However, operation was believed to be indicated only when intracoronary lysis was successful and myocardium was salvaged. Since left ventricular angiography proved unreliable in assessing the viability of the myocardium in the acute stage, starting in March of 1981 we obtained intracoronary thallium 201 scintiscans in 23 patients before and after intracoronary lysis. Patients in whom there was a significant reduction (greater than 50%) in the initial 201Th defect (n = 12) were considered ideal candidates for operation (Group 3). Patients with poor or unimproved 201Th uptake after successful intracoronary lysis (n = 6) were treated medically (Group 2), as were patients in whom intracoronary lysis was unsuccessful (n = 5, Group 1). In order to validate this new approach, we compared the change in the regional wall motion of the "infarcted area," as shown in the early and follow-up left ventricular angiograms in all three groups. In the acute stage, the mean regional ejection fraction was 19.9% in Group 1, 19.1% in Group 2, and 20.1% in Group 3. Only in Group 3 was there a significant increase in regional ejection fraction to a mean of 51%. The mean ejection fraction obtained at follow-up in Groups 1 and 2 was 16.5% and 17.3%, respectively. From our findings, we conclude that 201Th scintigraphy is a valuable predictor of the salvageability of myocardium immediately following intracoronary lysis. To date, it has been the most valuable tool in assessing those patients suitable for early coronary revascularization.

Coronary Vessels↗
PubMed1983

Effect of interventions in salvaging left ventricular function in acute myocardial infarction: a study of intracoronary streptokinase.

The ability of intracoronary streptokinase (STK) infused early in acute myocardial infarction (MI) to salvage left ventricular (LV) function was studied in 52 patients who underwent contrast angiography immediately after STK and 6 +/- 7 weeks later. Ten nonrevascularized patients had no lysis or reocclusion. Of 42 patients with thrombolysis, 22 with optimal reperfusion underwent coronary artery bypass grafting (CABG) to prevent rethrombosis (STK + CABG group) and 20 did not (STK group). Motion was measured at 100 chords around the left ventricle and expressed in standard deviations (SD) from the normal mean. Hypokinesia was computed as the mean motion of chords in the infarct artery territory and hyperkinesia on the opposite wall was similarly computed. Hypokinesia improved greater than or equal to 1 SD/chord in 9 STK + CABG patients (41%), 8 STK patients (30%) (p = not significant versus STK + CABG) and 0 nonrevascularized patients. However, the ejection fraction did not change because it was normal in acute MI despite severe hypokinesia due to hyperkinesia on the opposite wall, and a subsequent decrease in hyperkinesia masked significant improvement in hypokinesia. It is concluded that regional wall motion must be measured to adequately assess the effect of therapeutic interventions on LV function. Early thrombolysis in acute MI results in improved LV function. The main benefit of CABG is to prevent rethrombosis.

Adult↗