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Biomedical subjects

G J Laarman

Publications and source records attributed to G J Laarman.

At least 19 recordsLinked to original sources
PubMed1992

Restenosis after coronary angioplasty: the paradox of increased lumen diameter and restenosis.

Restenosis after coronary angioplasty is the single complication that most limits this revascularization procedure in clinical practice. The process is largely unpredictable and the lesion-related factors predisposing to restenosis are poorly understood, with little consensus in published reports. In this study using detailed quantitative angiographic measurements to assess 490 lesions, the simple lesion characteristics associated with restenosis were defined and the relation to the restenosis process documented. Restenosis was defined as an absolute deterioration in the minimal lumen diameter by greater than or equal to 0.72 mm, a criterion based on the 95% confidence intervals for repeat angiographic measurements. This was chosen in an attempt to separate spurious changes due to a poor angiographic result and the variability of angiographic measurements from significant changes due to the restenosis process. The principal determinants of restenosis were found to be a large improvement in the minimal lumen diameter at the time of dilation (1.13 mm for the restenosis group compared with 0.86 mm for the no restenosis group [p less than 0.0001]) and an optimal postangioplasty result (minimal lumen diameter 2.28 mm in the restenosis group compared with 2.05 mm [p less than 0.001] in the no restenosis group, corresponding to a 25% and a 30% diameter stenosis, respectively [p less than 0.0001]). These observations reported for the first time suggest that the distinction needs to be made between a "clinical restenosis" of greater than or equal to 50% diameter stenosis and the "restenosis process" as measured by the absolute changes occurring during and after angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1991

Percutaneous coronary rotational angioplasty: preliminary clinical and quantitative imaging results.

To determine anatomical and functional changes within the first 24 hours after percutaneous coronary rotational angioplasty (PCRA-ROTABLATOR, Biophysics International, USA), we studied 5 patients (4 men) with a mean age of 55 years (range 52-59) using quantitative coronary angiography, coronary flow reserve from digitized coronary angiograms, quantitative left ventricular angiography, and 99mTechnetium-MIBI SPECT imaging before PCRA, immediately after, and 24 hours after. The minimal luminal diameter and obstruction area showed a moderate increase immediately after PCRA, with a substantial further improvement after 24 hours. The mean coronary flow reserve before PCRA and 24 hours after (1.65 +/- 0.31 vs. 1.81 +/- 0.37; p = NS) remained unchanged. Although the global ejection fraction showed slight impairment immediately after PCRA, this was restored 24 hours later. Only the contribution to regional ejection fraction in the regions supplied by the treated coronary artery attributed to the decrease of global ejection fraction. Before and after PCRA, Tc-99m MIBI tomography performed at rest revealed no perfusion defects in the myocardial regions related to the coronary arteries undergoing the intervention.

Angioplasty, Balloon, Coronary↗
PubMed1991

Inability of coronary blood flow reserve measurements to assess the efficacy of coronary angioplasty in the first 24 hours in unselected patients.

To determine functional and anatomic changes in the first 24 hours after coronary angioplasty, we studied at random 15 patients (9 men, mean age 60 years) who underwent coronary angioplasty of 16 coronary arteries. Quantitative coronary angiography and coronary flow reserve measurements from digitized coronary angiograms were performed before, immediately after, and 24 hours after coronary angioplasty. Calculated were the minimal luminal diameter, obstruction area, and percentage diameter stenosis from two preferably orthogonal projections. Prior myocardial infarction in the myocardial region of interest was present in four patients. Seven patients had multivessel disease. Collateral vessels supplying the compromised flow region were observed in three patients. Six patients had refractory unstable angina pectoris. After coronary angioplasty, angiographically visible dissection was noted in six patients, whereas side branch occlusion was observed in one. Minimal luminal diameter before, immediately after, and 24 hours after was 0.93 +/- 0.18 mm, 1.53 +/- 28 mm, and 1.53 +/- 0.21 mm, respectively; obstruction area was 0.70 +/- 0.26 mm2, 1.92 +/- 0.69 mm2, and 1.87 +/- 0.51 mm2, respectively; diameter stenosis was 60.4 +/- 8.0%, 36.8 +/- 11.4%, and 37.6 +/- 5.3%, respectively. The coronary flow reserve (lower limit of normal with this technique 3.4) was essentially the same before and immediately after coronary angioplasty (1.26 +/- 0.59 vs 1.30 +/- 0.42, p = NS) with a slight improvement to 1.78 +/- 0.90 (p less than 0.05) 1 day later. Coronary artery dimensions correlated poorly with coronary blood flow reserve before and after angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography, Digital Subtraction↗
PubMed1991

Acute coronary artery occlusion during and after percutaneous transluminal coronary angioplasty. Frequency, prediction, clinical course, management, and follow-up.

BACKGROUND: Acute coronary artery occlusion after percutaneous transluminal coronary angioplasty (PTCA) continues to remain a serious complication despite significant improvement in operator performance and technological advancements. This retrospective study was performed to ascertain the frequency, predictive variables, management, and outcome of acute coronary artery occlusion. METHODS AND RESULTS: The study was based on data from 1,423 consecutive patients who underwent an elective coronary angioplasty between January 1986 and December 1988. Acute coronary artery occlusion occurred in 104 patients (7.3%). Acute occlusion developed during the dilatation procedure in 80 patients (5.6%) and within 24 hours after the procedure in 24 patients (1.7%). Four clinical and 14 angiographic variables predictive for acute coronary artery occlusion were analyzed in these 104 patients with a complicated procedure and were compared with those in 104 representative patients with successful attempts. Multivariate analysis found three independent predictive variables: unstable angina, multivessel disease, and complex lesions. The overall clinical outcome after management of acute coronary artery occlusion including immediate repeat dilatation (95 patients), use of intracoronary streptokinase (34 patients), or autoperfusion catheter (12 patients) was successful (reduction of lumen diameter to less than 50%, no death, no myocardial infarction [MI], and no emergency surgery) in 42 patients (40%), was a failure without major complication in four patients (4%), and was a failure with major complication (death, MI, and emergency surgery) in 58 patients (56%). The overall mortality rate was 6% (six patients), the overall MI rate was 36% (37 patients), and emergency bypass surgery was required in 30% of patients (31 patients). At 6 months' follow-up of 42 patients with successful management, recurrent angina pectoris due to restenosis occurred in 10 patients (24%), and a late MI occurred in one patient (3%). At 6 months' follow-up of 56 survivors with unsuccessful management (development of MI or need for emergency bypass surgery), recurrent angina occurred in nine patients (16%), and cardiac death in two patients (4%). However, the majority of patients in both groups were either symptom free or had mild angina pectoris. CONCLUSION: Acute coronary artery occlusion during PTCA is often unpredictable, but its frequency is higher in patients with unstable angina, multivessel disease, and complex lesions. Despite immediate redilatation, use of intracoronary streptokinase, and emergency bypass surgery, PTCA is associated with a high mortality and morbidity.

Acute Disease↗
PubMed1991

Inadequate exercise leads to suboptimal imaging. Thallium-201 myocardial perfusion imaging after dipyridamole combined with low-level exercise unmasks ischemia in symptomatic patients with non-diagnostic thallium-201 scans who exercise submaximally.

This study was undertaken to establish the additional value of 201TI imaging after dipyridamole in combination with low-level exercise in 15 symptomatic patients with non-diagnostic 201TI scans, who exercised submaximally. Most patients had angina, ST-segment depression and even exertional hypotension and were referred for stress 201TI testing for determining the functional significance of known coronary artery disease. Six patients with a normal exercise 201TI test and one patient with an apical defect only were found to have 37 segments (of 105 segments) with reversible perfusion defects after dipyridamole infusion. One patient showing two reversible defects after exercise had five reversible segments after dipyridamole. Seven patients with fixed defects in 28 segments after exercise and two with small areas of border zone ischemia in seven additional (sub)segments, demonstrated fixed in defects in only nine segments but reversible defects in 40 segments after dipyridamole. Quantitative analysis resulted in 24.8 +/- 28.5 (mean value) sample points below -2 s.d. of the mean normal uptake after exercise, which increased to 72 +/- 26.5 after dipyridamole infusion (p less than 0.005). The washout analysis resulted in a mean value of 5.5 +/- 8.1 sample points below -2 s.d. after exercise, increasing to 33.3 +/- 22.1 after dipyridamole (p less than 0.005). Thallium-201 myocardial perfusion imaging after dipyridamole combined with low-level upright bicycle exercise may unmask scintigraphic evidence for ischemia in symptomatic patients who would otherwise have non-diagnostic imaging studies during submaximal exercise.

Coronary Disease↗
PubMed1990

Quantitative angiographic assessment of elastic recoil after percutaneous transluminal coronary angioplasty.

Little is known about the elastic behavior of the coronary vessel wall directly after percutaneous transluminal coronary angioplasty (PTCA). Minimal luminal cross-sectional areas of 151 successfully dilated lesions were studied in 136 patients during balloon inflation and directly after withdrawal of the balloon. The circumvent geometric assumptions about the shape of the stenosis after PTCA, a videodensitometric analysis technique was used for the assessment of vascular cross-sectional areas. Elastic recoil was defined as the difference between balloon cross-sectional area of the largest balloon used at the highest pressure and minimal luminal cross-sectional area after PTCA. Mean balloon cross-sectional area was 5.2 +/- 1.6 mm2 with a mean minimal cross-sectional area of 2.8 +/- 1.4 mm2 immediately after inflation. Oversizing of the balloon (balloon artery ratio greater than 1) led to more recoil (0.8 +/- 0.3 vs 0.6 +/- 0.3 mm, p less than 0.001), suggestive of an elastic phenomenon. A difference in recoil of the 3 main coronary branches was observed: left anterior descending artery 2.7 +/- 1.3 mm2, circumflex artery 2.3 +/- 1.2 mm2 and right coronary artery 1.9 +/- 1.5 mm2 (p less than 0.025). The difference was still statistically significant if adjusted for reference area. Thus, nearly 50% of the theoretically achievable cross-sectional area (i.e., balloon cross-sectional area) is lost shortly after balloon deflation.

Absorptiometry, Photon↗
PubMed1990

[Percutaneous transluminal coronary angioplasty in patients older than 70 years; short- and long-term results].

PTCA was performed in 166 patients older than 70. The primary angiographic and clinical success rates were 85% and 86%, respectively. A total of 15 major complications occurred in 10 patients (6%): 4 patients died (2%), 6 patients underwent urgent bypass surgery (4%), the incidence of acute myocardial infarction was 3% (5 patients). The 4-year survival rate was 84 +/- 8%. During the follow-up period 8 patients (5%) sustained a nonfatal myocardial infarction, 21 patients (13%) underwent a second and (or) third balloon dilatation and 17 patients (10%) underwent bypass surgery. At the end of the observation period 68% of the survivors had a sustained improvement of the functional class. This was associated with a significant reduction of the antianginal therapy. These data demonstrate that PTCA can be performed safely and effectively in patients over 70.

Aged↗
PubMed1990

[Directional coronary atherectomy; initial Dutch experiences with a new percutaneous revascularization procedure].

Acute complications and restenosis in the first few months after a successful procedure remain the two major limitations of coronary balloon angioplasty. New devices have been developed in order to avoid these limitations. We tested the directional atherectomy catheter clinically and compared the immediate quantitatively analysed results with two other recently developed devices and conventional balloon angioplasty. A gain in luminal diameter of 1.7 mm after atherectomy was observed in 7 patients. This is far more than could be accomplished by balloon angioplasty, stenting and rotablation. Furthermore, the size of the device in relation to the size of the obstructed vessel suggests that a Dotter effect is partly responsible for the gain in luminal diameter. Whether this large gain can prevent restenosis remains to be confirmed. Preliminary literature data suggest that this is not the case.

Adult↗
PubMed1990

Is quantitative analysis superior to visual analysis of planar thallium 201 myocardial exercise scintigraphy in the evaluation of coronary artery disease? Analysis of a prospective clinical study.

Quantitative analysis of myocardial exercise scintigraphy has been previously reported to be superior to visual image interpretation for detection of the presence and extent of coronary artery disease. Computer analysis of perfusion defects and washout rate of thallium 201 was performed on scintigrams from a group of 131 consecutive patients (prospective group), using criteria defined from a previous group of 72 patients (initial group), and compared with visual interpretation of scintigrams for detection and evaluation of coronary artery disease. The sensitivity of the quantitative technique with regard to overall detection of coronary artery disease was not significantly different from the visual method (69% and 74%, respectively), whereas the specificity was higher (86% and 68%). Quantitative analysis did not increase the sensitivity of thallium imaging over the visual method in the left anterior descending artery (46% vs 65%) and the right coronary artery (51% vs 72%) but did increase sensitivity in the left circumflex artery (75% vs 47%). Whereas in the initial group quantitative analysis resulted in a better identification of multivessel disease (sensitivity 81% vs 57%), in the prospective group sensitivity decreased (54% vs 67%) without significant loss of specificity. The initial group had a 40% incidence of three-vessel disease and the prospective group, 22% (P less than 0.05). One-vessel disease was higher in the prospective group (32% vs 11%, P less than 0.05). Thus, assessing the quantitative technique in a larger prospective patient population, there was no improvement of detection of the presence and extent of coronary artery disease when compared with visual interpretation.

Coronary Disease↗
PubMed1990

PTCA of chronically occluded coronary arteries.

The occlusion of a coronary artery does not necessarily imply the existence of nonviable myocardium of that flow-dependent region, because the presence of a well developed collateral circulation may be a sufficient nutrient source. During an episode of increased demand for myocardial oxygen, this collateral blood supply may become insufficient, and symptoms of myocardial ischemia may arise. PTCA of the occluded vessel appears to be an attractive approach to relieve ischemia in this situation. The primary success of dilatation of totally occluded segments depends largely on the duration of the occlusion but also on anatomic factors such as total or functional occlusion, the length of the occluded segment, and good angiographic visualization of the coronary artery distal to the occlusion by collaterals. The primary success rate (+/- 60%) of PTCA of occluded vessels is lower than the success rate (greater than 90%) of PTCA of nonocclusive stenoses. Also the restenosis rate (+/- 40%) and subsequent recurrence rate of angina pectoris is higher, compared to the 30% restenosis rate after dilatation of conventional lesions. Newer percutaneous techniques such as lasers, newly designed guide wires, and intravascular imaging devices are necessary to increase the primary success rate. Whether these techniques will also improve the long-term results remains uncertain.

Angioplasty, Balloon, Coronary↗
PubMed1990

Thallium-201 scintigraphy after dipyridamole infusion with low level exercise. II. Quantitative analysis vs visual analysis.

To determine the value and limitations of quantitative analysis of thallium-201 imaging after intravenous dipyridamole in combination with low level exercise, 81 patients with suspected coronary artery disease (CAD) were evaluated prospectively. The results of quantitative analysis were compared with the results of visual analysis. All patients underwent coronary arteriography and left ventricular angiography. Significant CAD was present in 59 patients (73%); multivessel CAD was observed in 33 patients (42%). Mild side-effects such as headache, vertigo and nausea were experienced by 12 patients (15%). To establish 'test-specific' normal limits in quantitative analysis of uptake and washout of thallium-201 after dipyridamole infusion with low level exercise we studied 20 healthy volunteers with a likelihood of CAD less than or equal to 1%. Sensitivity and specificity of quantitative analysis for overall detection of significant CAD were 76% and 73%, respectively vs 78% and 86%, respectively with visual analysis (P = NS). Sensitivity for the detection of multivessel CAD was slightly higher with quantitative analysis (73%) than with visual analysis (70%), but the specificity was lower (75% vs 92%) (P = NS). Sensitivity of quantitative analysis in relation to vessels involved was slightly lower than with visual analysis (RCA and LAD: P = NS; LCX: P less than 0.05). Of 14 patients with false-negative results, four had multivessel CAD. Thus, quantitative analysis after the combination of dipyridamole infusion with low level exercise did not improve the diagnostic value as assessed by semi-quantitative visual analysis.

Adult↗
PubMed1990

Thallium-201 scintigraphy after dipyridamole infusion with low-level exercise. III. Clinical significance and additional diagnostic value of ST segment depression and angina pectoris during the test.

Intravenous dipyridamole thallium testing is a useful alternative procedure for assessing coronary artery disease (CAD) in patients who are unable to perform maximal exercise tests. Ischaemic ST segment depression and angina pectoris are frequently observed during the test, in particular when exercise is added to dipyridamole infusion. To establish the clinical significance and additional diagnostic value of these markers of ischaemia during dipyridamole low-level exercise testing (DXT) 57 patients with CAD (group A), 21 patients with normal or near-normal coronary arteries at coronary arteriography (group B), and 20 healthy subjects with low likelihood of CAD (group C) were studied. During DXT ischaemic ST segment depression was observed in 28 patients (47%) of group A and in two patients (10%) of group B. Angina pectoris was experienced by 35 patients (61%) of group A and by five patients (24%) of group B. The positive predictive value of both ST depression and angina pectoris was high (88 and 93%, respectively), but the negative predictive values were low (42 and 40%, respectively). Combining ST segment analysis with the findings of thallium imaging significantly increased the diagnostic accuracy of the test. ST segment depression, angina pectoris, and thallium abnormalities were highly specific findings if the study population consisted of asymptomatic subjects with a low likelihood of CAD (group C). Sensitivity for the detection of the presence of CAD increased with the extent of CAD for all parameters studied. Thus, ST depression and angina pectoris, alone or in combination, during DXT have little diagnostic significance, although sensitivity is increased in patients with triple-vessel CAD.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Quantitative thallium-201 scintigraphy after dipyridamole infusion combined with low level exercise in healthy volunteers.

To establish test specific normal limits for quantitative analysis of uptake and washout of 201Tl after dipyridamole infusion combined with low level exercise, 20 healthy volunteers were studied with low likelihood of coronary artery disease (CAD) assessed by a stepwise probability analysis based on age, sex, symptoms, resting electrocardiogram, and exercise electrocardiography. Likelihood of CAD in these volunteers was calculated as less than or equal to 1%. After dipyridamole infusion combined with low level exercise, one volunteer complained of headache; no other side effects were observed. There were no chest pain complaints. Maximal hemodynamic changes were achieved during the 6th and 7th min of the test. No ST segment depression was recorded. Visual analysis of the 201Tl scintigrams was normal in all volunteers. Mean regional washout at 4 h was 44.37% +/- 2.11%. The regional washout in the 70 degrees LAO view (46.65% +/- 1.10%) was significantly higher than in the anterior and 30 degrees LAO views (43.44% +/- 1.50% and 43.02% +/- 1.45%, respectively). Profiles of uptake and washout of 201Tl were different after dipyridamole infusion combined with low level exercise as compared to maximal exercise. Thus, in quantitative analysis of 201Tl scintigraphy after dipyridamole infusion in conjunction with low level exercise as applied in the present study, it is mandatory to use normal limits of uptake and washout of 201Tl derived from healthy volunteers who underwent the same combined protocol.

Adult↗
PubMed1989

A comparison of two methods to measure coronary flow reserve in the setting of coronary angioplasty: intracoronary blood flow velocity measurements with a Doppler catheter, and digital subtraction cineangiography.

Intracoronary blood flow velocity measurements with a Doppler balloon catheter and the radiographic assessment of myocardial perfusion with contrast media, before and after the intracoronary administration of papaverine, have previously been used to investigate regional coronary flow reserve. In the present study we applied both techniques in 21 patients to measure coronary flow reserve in the setting of coronary angioplasty. Pre-angioplasty (N = 14) and post-angioplasty (N = 19) measurements of coronary flow reserve were obtained by digital subtraction cineangiography in the myocardial region supplied by the dilated coronary artery, and with the Doppler probe in the proximal part of the dilated vessel. The reactive hyperaemia following the final balloon inflation was recorded with the Doppler balloon catheter still positioned across the stenotic lesion. Coronary stenosis geometry was quantified with the Cardiovascular Angiography Analysis System. When the epicardial stenosis was the only factor causing a reduction in coronary flow reserve, flow reserve measured with both digital subtraction cineangiography and with the Doppler probe correlated well with the cross-sectional area at the site of obstruction, r = 0.88, SEE = 0.36 and r = 0.77, SEE = 0.45 respectively. In contrast, when other factors decreasing coronary flow reserve were present (intimal dissection, left ventricular hypertrophy, previous myocardial infarction, collaterals) measurements obtained with both techniques correlated poorly with cross-sectional area (r = 0.55, SEE = 0.57, and r = 0.59, SEE = 0.50). Flow reserve measurements obtained with digital subtraction cineangiography correlated well with the measurements obtained with the Doppler probe (r = 0.85, SEE = 0.38, and r = 0.87, SEE = 0.34), although the two approaches have methodologically nothing in common and their respective regions of interest (myocardium for the radiographic technique and intracoronary lumen for the Doppler technique) are basically different. Furthermore, the reactive hyperaemia following the final balloon inflation was related to the flow reserve measured with both the angiographic technique (r = 0.85, SEE = 0.34) and the Doppler technique (r = 0.83, SEE = 0.32) using pharmacologically induced coronary vasodilation with intracoronary papaverine. This suggests that the same quantity of coronary flow reserve that can be recruited pharmacologically can be recruited by ischaemia following a transluminal occlusion.

Adult↗