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Biomedical subjects

W Wijns

Publications and source records attributed to W Wijns.

At least 127 records · Page 7Linked to original sources
PubMed1986

Preservation of global and regional left ventricular function after early thrombolysis in acute myocardial infarction.

The effect of early myocardial reperfusion (within 4 hours after onset of symptoms) on regional left ventricular function in patients with acute myocardial infarction has been quantitated by analysis of segmental wall motion. Of 533 patients randomized either to conventional coronary care unit therapy or to a reperfusion strategy, in 332 high quality angiograms were obtained 2 to 8 weeks after the onset of myocardial infarction. In those assigned to thrombolytic therapy, angiographic data were also available after acute reperfusion. Analysis on an "intention to treat" basis revealed significant preservation of left ventricular function after thrombolytic therapy (ejection fraction 53%) compared with conventional treatment (ejection fraction 47%). In addition, wall motion analysis showed significant improvement of regional function in the infarct zone in both inferior and anterior infarction. In addition, significant changes occurred in regional function of the remote "noninfarct zone" in the acute as well as the chronic stage. It is concluded that improved regional and global left ventricular function can be achieved with early reperfusion and that this is the likely explanation for the reduction of early and late mortality after thrombolysis observed in this study.

Aged↗
PubMed1986

Effect of coronary occlusion during percutaneous transluminal angioplasty in humans on left ventricular chamber stiffness and regional diastolic pressure-radius relations.

The effect of repeated (3 to 10 second) and transient (15 to 75 second) abrupt coronary occlusion on the global and regional chamber stiffness was studied in nine patients undergoing angioplasty of a single proximal left anterior descending coronary artery stenosis. The left ventricular high fidelity pressure and volume relation was obtained before and after the procedure as well as during coronary occlusion, after 20 seconds (n = 9) and after 50 seconds (n = 5). During ischemia, there was an upward shift of the pressure-volume relation. The nonlinear simple elastic constant of chamber stiffness increased from 0.0273 +/- 0.017 before angioplasty (mean +/- SD) to 0.0621 +/- 0.026 after 20 seconds of occlusion (p less than 0.05) and 0.0605 +/- 0.015 after 50 seconds of occlusion (p less than 0.01). In five patients, the postangioplasty value remained higher than the control value, but at the group level the mean value (0.0529 +/- 0.037) was not statistically different. The regional stiffness was determined from the changes in the length of six segmental radii during diastole, from the lowest diastolic to the end-diastolic pressure. The regional constant of elastic stiffness was unaffected in the nonischemic zone. In the adjacent and ischemic zones, the regional stiffness was increased during occlusion (p less than 0.05). These regional abnormalities in diastolic function persisted at the time of postangioplasty measurements, 12 minutes after the end of the procedure. This suggests that recovery of normal diastolic function after repeated ischemic injuries is delayed after restoration of normal blood flow and systolic function.

Angioplasty, Balloon↗
PubMed1986

Coronary angioplasty of the unstable angina related vessel in patients with multivessel disease.

This study is a retrospective analysis of the efficacy of percutaneous transluminal coronary angioplasty of the ischaemia-related vessel in patients with unstable angina. Forty-three patients had multivessel disease with dilatation of the ischaemia-related vessel only (group I; partial revascularization) while 111 patients had single vessel disease only (group II; total revascularization). The initial success rate in both groups was identical (88 versus 88%). The need for emergency coronary artery bypass surgery was similar in the two groups (group I 12% versus group II 9%; NS). The total post PTCA myocardial infarction rate (despite urgent CABG) was also similar in the two groups (group I 9% versus group II 10%; NS). The results of electrocardiographic exercise testing and Thallium-201 scintigraphy provide objective evidence for incomplete revascularization in group I. The maximum workload achieved was lower, and the frequency of exercise induced angina, ST-segment depression and reversible perfusion defect was higher than in group II. Moreover, at 6 months follow-up the recurrence rate of angina pectoris rate was higher in group I than in group II (29% versus 16% P less than 0.05). It is concluded that dilatation of the ischaemia related vessel only in patients with unstable angina and multivessel disease is as effective in the management of the acute phase of unstable angina as is dilatation of the ischaemia related vessel in patients with single vessel disease. However, due to only partial revascularization the recurrence rate of angina pectoris is higher.

Adult↗
PubMed1986

Long term improvement in global left ventricular function after early thrombolytic treatment in acute myocardial infarction. Report of a randomised multicentre trial of intracoronary streptokinase in acute myocardial infarction.

The effect of reperfusion achieved by early intracoronary streptokinase in acute myocardial infarction on left ventricular function was studied in 533 patients enrolled in a prospective randomised multicentre study. Two hundred and sixty four patients were allocated to conventional treatment and 269 patients to thrombolysis. At the end of the procedure patency of the infarct related vessel was achieved in 198 (85%) of 234 patients in whom coronary angiography was performed. The median interval from onset of symptoms till the angiographic documentation of patency was 200 minutes. Data were analysed according to the original treatment allocation. Global left ventricular ejection fraction was determined by radionuclide angiography in 418 patients within two days of admission, in 361 patients after two weeks, and in 307 patients after three months. Global left ventricular function remained unchanged throughout the observation period in the control group, whereas it improved during the first two weeks in patients allocated to thrombolytic treatment. Improved function in these patients persisted up to three months after the infarction. Global left ventricular ejection fraction was significantly better in the thrombolysis group than in the control group at two days, two weeks, and at three months. In patients with anterior myocardial infarction the left ventricular ejection fraction was 9% better than in the control group at two weeks and at three months. In the patients with inferior myocardial infarction differences between the two treatment groups were smaller because of photon attenuation within the body. Angiographic evidence suggested that the improvement in function seen after thrombolysis is indeed associated with the patency of the infarct related artery.

Aged↗
PubMed1986

Early changes in wall motion and wall thickness during percutaneous transluminal coronary angioplasty in man.

Epicardial wall motion, myocardial wall thickness and segmental wall motion during percutaneous transluminal coronary angioplasty, a situation which resembles the experimental abrupt occlusion of a major coronary artery in the animal laboratory, have been studied in patients undergoing the procedure. Epicardial wall motion was analyzed using biplane cineradiography with frame to frame measurements of distances between pairs of radiopaque epicardial markers, placed at the time of previous cardiac surgery in a patient with a stenosis of a coronary artery bypass graft. Bypass graft occlusion led to early onset of biphasic epicardial late systolic lengthening and early diastolic shortening similar to the regional wall motion abnormality preceding the procedure. Continuous M-mode echocardiogram throughout coronary luminal occlusion, showed a decreased systolic thickening in the septum with a concomitant, prominent notch in early diastole occurring after the seventh beat following occlusion. At the 28th beat, septal systolic motion was absent while only an early diastolic septal motion was observed. Contemporaneously the end-diastolic septal thickness results decreased. Segmental wall motion analysis during ischemia was carried out performing a left ventricular angiogram before, 20 and 50 seconds after the onset of balloon inflation, 5 minutes after completion of the procedure. During the early phase of ischemia, in the ischemic segments, a late systolic lengthening with an early diastolic shortening was observed. We refer to this biphasic motion as the "W" phenomenon which appears to be the early and characteristic change in wall motion and thickness during coronary angioplasty in man.

Angioplasty, Balloon↗
PubMed1986

Effects of intracoronary thrombolysis on global left ventricular function assessed by an automated edge detection technique.

Three hundred and two patients with acute myocardial infarction were enrolled in a randomized multicenter trial to compare conventional treatment with attempted recanalization by intracoronary streptokinase. In a subgroup of patients, the effects of thrombolysis on left ventricular function were evaluated within 48 hr, at 2 wk, and at 3 mo after admission. Global left ventricular ejection fraction (LVEF) was obtained by radionuclide angiography and analyzed with an automatic detection program. Paired data were determined in 160 patients (control 78, thrombolysis 82) within 48 hr and at 2 wk, and in 143 patients (control 71, thrombolysis 72) at 48 hr, 2 wk, and 3 mo. It was shown that LVEF significantly improved in the thrombolysis group as compared with controls both at 2 wk (delta LVEF thrombolysis 3.9 +/- 7.9%, p less than 0.001 compared with delta LVEF control 0.6 +/- 9.7%, p = N.S.) and at 3 mo (delta LVEF thrombolysis 3.1 +/- 12.4%, p less than 0.05 compared with delta LVEF control 2.1 +/- 12.2%, p = N.S.). When patients were divided according to infarct site, however, significant improvement at 3 mo was only observed in the patients with anterior infarction (delta LVEF thrombolysis 5.5 +/- 13.1%, p less than 0.05 compared with delta LVEF control 3.3 +/- 10.4%, p = N.S.). It was shown that acute intervention with intracoronary streptokinase has a potentially favorable and lasting effect on left ventricular function in patients with anterior myocardial infarction. This improvement might be related to the rather rapid administration of thrombolytic therapy with a median time of approximately 4 hr after onset of symptoms.

Adult↗
PubMed1985

Acute effects of intravenous nisoldipine on left ventricular function and coronary hemodynamics.

The hemodynamic effects of nisoldipine were investigated in 16 patients with suspected coronary artery disease who underwent routine cardiac catheterization. Nisoldipine was given intravenously in a dose of 6 micrograms/kg over 3 minutes and measurements made before and after drug administration during spontaneous and matched atrial paced heart rate. During sinus rhythm, nisoldipine produced a significant increase in heart rate (19%, p less than 10(-5]. Left ventricular systolic pressure decreased 28% (p less than 10(-6) and left ventricular end-diastolic pressure did not change significantly (5%, difference not significant). Coronary sinus and great cardiac vein blood flow increased by 21% (p less than 0.02) and 25% (p less than 0.005), respectively, after nisoldipine administration. Simultaneously, mean aortic pressure decreased 33% (p less than 10(-6]; consequently, the global and regional coronary vascular resistances decreased by 50% (p less than 10(-4]. The decreases in global (-8%) and regional (-4%) myocardial oxygen consumption did not reach statistical significance. A 6% (not significant) increase in end-diastolic volume and an 11% (p less than 0.002) decrease in end-systolic volume resulted in an increase of 21% in stroke volume (p less than 10(-4] with a consistent increase in ejection fraction (+16%, p less than 10(-5]. Total systemic vascular resistance was reduced by 30% (p less than 0.0002). During spontaneous heart rate and matched atrial pacing, the time constant of isovolumic relaxation as assessed by a biexponential model, was significantly shortened.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

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

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.

Angina Pectoris↗
PubMed1985

Radionuclide absolute left ventricular volumes during upright exercise: validation in normal subjects by simultaneous hemodynamic measurements.

A nongeometric radionuclide technique for the determination of absolute left ventricular volumes was validated during exercise in nine normal subjects. Simultaneous reference stroke volume and cardiac output measurements were obtained by the Fick method. The reference left ventricular volumes were calculated by combining the Fick stroke volume and the isotopic ejection fraction. Data were collected at rest in the supine and upright positions and during 60 degrees upright exercise, at three levels of increasing severity. At rest, from supine to upright position, the reference end-diastolic volume decreased significantly from 182 +/- 24 ml to 154 +/- 21 ml (mean +/- SD, P less than 0.005); during upright exercise of low intensity, end-diastolic volume increased to 176 +/- 24 ml (P less than 0.05); at maximal exercise, end-diastolic volume was not different from the resting value in upright position. The end-systolic volume gradually decreased at rest from 67 +/- 11 ml in the supine position to 54 +/- 8 ml in the upright position (P less than 0.05). Compared with these reference data, the scintigraphic measurements were significantly lower on average by 23% for stroke volume, 21% for cardiac output, 22% for end-diastolic volume, and 23% for end-systolic volume. The overall changes in stroke volume (P less than 0.05) and end-systolic volume (P less than 0.001) occurring at rest and during exercise were correctly detected by the scintigraphic method but the smaller changes in end-diastolic volume (less than 15%) were not (P less than 0.15) because they were within the range of the precision of the technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Elective PTCA of totally occluded coronary arteries not associated with acute myocardial infarction; short-term and long-term results.

Of 652 consecutive patients referred for coronary angioplasty between September 1980 and March 1984, 49 patients presented with total or functional 'occlusion' of the involved vessel. Total vessel occlusion was defined as absent anterograde filling beyond the lesion. Functional occlusion was defined as faint, late anterograde opacification of the distal segment in the absence of a discernible luminal continuity. In 39 patients, the total or functional occlusion represented a progression, without acute myocardial infarction, of a previously diagnosed stenotic lesion. The maximal potential duration of occlusion was estimated to be 4 weeks or less in 21 patients, more than 4 to 8 weeks in 12, and more than 8 weeks in 16. Dilation of the occluded artery was attempted in the left anterior descending coronary artery in 30 patients, in the right coronary artery in 8, in the circumflex coronary in 7 and in 4 jumpgrafts. For the whole group, angioplasty was successful in 28 patients (57%). The primary success rate with the functionally occluded vessel (81%) was significantly higher than with the total occlusion (45%). In 33 patients with an occlusion estimated to be of 8 weeks or less, angioplasty was successful in 65%. In the 16 patients with an occlusion estimated to be of 8 weeks or less, angioplasty was successful in 65%. In the 16 patients with an occlusion estimated to be of more than 8 weeks duration, dilation was successful in 44%. Of the 21 patients in whom angioplasty was unsuccessful, 11 required surgery (1 urgent with persistent pain and ST elevation and 10 elective). Ten patients were maintained on medical treatment. Of the 28 patients in whom angioplasty was successful, 10 patients had recurrence of symptoms during follow-up (1-42 months). Four were kept on medical therapy, three required bypass surgery and three underwent repeat percutaneous transluminal coronary angioplasty (PTCA). After primary success, late angiographic studies obtained in 20 out of 28 patients showed reocclusion in 8. In conclusion, elective PTCA of totally occluded coronary arteries is feasible but the primary success rate is lower (57%) than that associated with conventional lesions. The long-term clinical results following successful angioplasty are satisfactory (64%), but the incidence of reocclusion is higher (40%).

Adult↗
PubMed1985

Left ventricular function during transluminal angioplasty: a haemodynamic and angiographic study.

The response of left ventricular function, was studied in a series of patients undergoing percutaneous transluminal coronary angioplasty (PTCA). From 4 to 6 balloon inflations procedures per patient were performed with an average duration per occlusion of 51 +/- 12 sec (mean +/- SD), total occlusion time 252 +/- 140 sec. Analysis of left ventricular (LV) haemodynamics showed that the relaxation parameters peak negative rate of change in pressure and the early time constant of relaxation responded earliest to acute coronary occlusion while other parameters such as peak pressure, LV end-diastolic pressure, and peak positive rate of change of pressure responded more gradually and suggested a progressive depression in myocardial mechanics during the entire procedure. LV angiogram available in 14 patients indicate an early onset of asynchronous relaxation concurrent with the early response in peak -dP/dt and the time constant of early relaxation. All haemodynamic parameters fully recovered within minutes after the end of PTCA. The results of this study indicate no permanent dysfunction to global or regional myocardial mechanics, after PTCA with 4 to 6 coronary occlusions each lasting 40 to 60 seconds.

Angiography↗
PubMed1985

Predictive value of early maximal exercise test and thallium scintigraphy after successful percutaneous transluminal coronary angioplasty.

Restenosis of the dilated vessel after percutaneous transluminal coronary angioplasty can be detected by non-invasive procedures but their ability to predict later restenosis soon after a successful angioplasty as well as recurrence of angina has not been assessed. A maximal exercise test and myocardial thallium perfusion scintigraphy were, therefore, performed in 91 asymptomatic patients a median of 5 weeks after they had undergone a technically successful angioplasty. Primary success of the procedure was confirmed by the decrease in percentage diameter stenosis from 64(12)% to 30(13)% as measured from the coronary angiograms and in the trans-stenotic pressure gradient (normalised for mean aortic pressure) from 0.61(0.16) to 0.17(0.09). A clinical follow up examination (8.6(4.9) months later) was carried out in all patients and a late coronary angiogram obtained in 77. The thallium perfusion scintigram showing the presence or absence of a reversible defect was highly predictive for restenosis whereas the exercise test was not. The positive predictive value of an abnormal scintigram was 82% compared with 60% for the exercise test (ST segment depression/or angina or both at peak workload). Angina or a new myocardial infarction occurred in 60% of patients with abnormal and in 21% of patients with normal scintigrams.

Adult↗
PubMed1985

Limitations of a QRS scoring system to assess left ventricular function and prognosis at hospital discharge after myocardial infarction.

The value of a QRS scoring system derived from 12 lead electrocardiograms to estimate left ventricular ejection fraction was assessed in a prospective study of 285 hospital survivors of myocardial infarction. In these patients both the QRS score and ejection fraction were measured by radionuclide ventriculography at discharge. The correlation between ejection fraction and QRS score was weak. In 22 patients who died during six to 12 months follow up the ability of the ejection fraction and QRS score to predict mortality was assessed in terms of sensitivity, specificity, predictive value of a positive and negative test, and efficiency. For ejection fraction less than 40% and a QRS score greater than or equal to 6 sensitivity was respectively 73% and 64%, specificity 73% and 56%, predictive value of a positive test 18% and 11%, predictive value of a negative test 97% and 95%, and efficiency 73% and 56%. Both ejection fraction and QRS score may be used to identify patients at low and high risk during one year follow up, but, contrary to initial expectations, the QRS score appears to be of little value in estimating ejection fraction and is less accurate than ejection fraction in predicting late survival in hospital survivors of myocardial infarction.

Adult↗
PubMed1985

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

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.

Angiography↗
PubMed1985

Assessment of short-, medium-, and long-term variations in arterial dimensions from computer-assisted quantitation of coronary cineangiograms.

A computer-assisted technique has been developed to assess absolute coronary arterial dimensions from 35 mm cineangiograms. The boundaries of optically magnified and video-digitized coronary segments and the intracardiac catheter are defined by automated edge-detection techniques. Contour positions are corrected for pincushion distortion. The accuracy and precision of the edge detection procedure as assessed from cinefilms of contrast-filled acrylate (Perspex) models were -30 and 90 micrometers, respectively. The variability of the analysis procedure itself in terms of absolute arterial dimensions was less than 0.12 mm, and in terms of percentage arterial narrowing for coronary obstructions less than 2.74%. Short-, medium-, and long-term variability measurements were assessed from repeated coronary angiographic examinations performed 5 min, 1 hr, and 90 days apart, respectively. For all studies the mean differences in absolute diameters were less than 0.13 mm. The variability in obstruction diameter ranged from 0.22 mm for the best-controlled study (medium-term) to 0.36 mm for the least-controlled study (long-term); variability in reference diameter ranged from 0.15 to 0.66 mm, respectively. It is concluded that the biological variations are a source of major concern and that further attempts toward standardization of the angiographic procedure are seriously needed.

Cineangiography↗