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Biomedical subjects

R Erbel

Publications and source records attributed to R Erbel.

At least 253 records · Page 14Linked to original sources
PubMed1997

Intravascular ultrasound in patients with acute pulmonary embolism after treatment with intravenous urokinase and high-dose heparin.

OBJECTIVE: To compare the diagnostic value of intravascular ultrasound (IVUS) with angiography in patients with pulmonary embolism. DESIGN: Open, prospective clinical study. SETTING: Two university hospitals. PATIENTS: Angiography and IVUS were used in 11 patients (5 men) (mean (SD) age 50 (18) years) with acute pulmonary embolism. INTERVENTIONS: At a mean (SD) of 6 (4) hours after thrombolytic therapy with urokinase and full-dose heparin, all patients underwent pulmonary artery angiography. Then 3.5 F mechanical, 20 or 30 MHz IVUS catheters were advanced into the pulmonary circulation. MAIN OUTCOME MEASURES: The pulmonary circulation was studied by both methods to detect the presence of thrombus, and a modified Miller score (assessing perfusion defects only and not velocity of flow) was used to quantify the angiographic images. RESULTS: The modified Miller score was mean (SD) 7.4 (2.3) points. 168 pulmonary artery segments (diameter range 2-14 mm) were studied by angiography and IVUS. On angiography, seven segments showed complete obstruction and 49 partial obstruction; 112 were normal. Two distinct types of thrombus formation were found by IVUS. Type A thrombus only partly adhered to the wall but otherwise was mobile and type B predominantly adhered to the wall. IVUS confirmed all seven angiographically complete obstructions but missed three (6%) of the 49 partial occlusions. Forty (87%) of the remaining 46 segments had type A thrombus and six (13%) type B. IVUS indicated a thrombus in 38 (34%) of the 112 angiographically normal segments; 20 (53%) showed a type A pattern and 18 (47%) a type B pattern (P < 0.001). CONCLUSION: IVUS was more sensitive than angiography in detecting thrombus but the clinical impact of this finding is not clear as yet.

Acute Disease↗
PubMed1996

[Intravascular ultrasound for monitoring percutaneous fenestration of a membrane from an aortic dissection].

HISTORY AND CLINICAL FINDINGS: A 51-year-old man, having experienced sudden retrosternal pain was admitted to another hospital with suspected myocardial infarction. He also had dysaesthesia and later paresis of the left leg. There was no sign of acute infarction in the ECG. However, computed tomography revealed aortic dissection, type III (DeBakey). The left pedal pulses were diminished. The patient was transferred to our hospital for further diagnosis and treatment. At a blood pressure of 110/60 mm Hg the occlusion pressure of the leg artery was 55 mm Hg on the left and 95 mm Hg on the right. INVESTIGATIONS: Transoesophageal echocardiography detected no abnormality of the aortic valve and ascending aorta. But distal to the origin of the left subclavian artery it demonstrated a free floating membrane of an aortic dissection and computed tomography showed its extension to the aortic bifurcation. TREATMENT AND COURSE: At first, because of the incomplete ischaemia syndrome affecting the left leg, a percutaneous fenestration of the dissection membrane was performed. After conventional angiography intravascular ultrasound imaging was also undertaken; it revealed that the membrane was almost completely occluding the left iliac artery. Under ultrasound monitoring a puncture needle and two balloon catheters were introduced across the membrane and thus a window created in it. The clinical findings quickly disappeared and the patient was discharged without further operation. CONCLUSION: Monitoring with intravascular ultrasound imaging makes it possible to perform safely a percutaneous fenestration of the membrane of an aortic dissection and to obtain immediate evidence of its success.

Aortic Dissection↗
PubMed1996

Comparison of myocardial perfusion reserve before and after coronary balloon predilatation and after stent implantation in patients with postangioplasty restenosis.

BACKGROUND: Stents provide a scaffold for coronary arteries after angioplasty and inhibit elastic recoil. METHODS AND RESULTS: In 25 patients with postangioplasty restenosis of the left anterior descending artery, ECG-gated digital subtraction coronary angiograms were recorded at baseline and during hyperemia (12 mg papaverine IC) before and after balloon predilatation (PTCA), after implantation of a Palmaz-Schatz stent, and after 6 months. Densitometric evaluation revealed different time and density parameters to calculate two definitions of myocardial perfusion reserve (MPR1 and MPR2) and maximum flow ratio (MaxFR). Poststenotic MPR1 increased from 1.57 +/- 0.14 to 2.59 +/- 0.86 after PTCA and to 3.10 +/- 0.41 after stenting, with 2.90 +/- 0.65 at follow-up (ANOVA, P < .05), while reference MPR1 remained unchanged at 3.10 +/- 0.40. Poststenotic MPR2 increased from 1.36 +/- 0.28 to 2.50 +/- 1.20 and to 3.40 +/- 0.58, respectively, with 3.20 +/- 0.92 at follow-up (ANOVA, P < .05), while reference MPR2 remained unchanged at 3.40 +/- 0.60. MaxFR was 2.13 +/- 0.53 after PTCA, elasticity 2.83 +/- 0.35 after stenting, and 2.73 +/- 0.58 at follow-up (ANOVA, P < .05). A good correlation was found between minimal stenotic luminal diameter and MPR1 or MPR2 (r = .87 and r = .94) and between luminal gain and MaxFR (r = .75). A negative correlation was measured between recoil and MPR1, MPR2, and MaxFR (r = -.80, r = -.86, and r = -.83). At follow-up, a steeper correlation was found between MPR and minimal stenosis diameter (MPR1: slope, 0.52 versus 0.91; MPR2: slope, 1.48 versus 1.95) and between MaxFR and net lumen gain (slope, 0.78 versus 1.27). CONCLUSIONS: Coronary stent implantation in patients with postangioplasty restenosis normalized poststenotic myocardial perfusion immediately as a result of a larger postprocedural lumen and a more pronounced inhibition of elastic recoil. After 6 months this benefit was sustained despite progressive lumen loss.

Absorptiometry, Photon↗
PubMed1996

[Intensive medical monitoring with transesophageal echocardiography in fulminant pulmonary embolism].

HISTORY AND FINDINGS: A 60-year-old man underwent a continence-preserving anterior rectal resection for a high rectal carcinoma. After mobilisation on the 5th postoperative day dyspnoea and cyanosis suddenly developed requiring emergency intubation and mechanical ventilation. INVESTIGATIONS: His heart rate was 160/min, blood pressure 80/50 mmHg, mean pulmonary artery pressure by indwelling catheter was 70 mmHg. The electrocardiogram had the classical signs of acute right-heart overload. Transoesophageal echocardiography (TOE) demonstrated marked right-heart and pulmonary artery dilatation. TREATMENT AND COURSE: Despite thrombolytic treatment (bolus of 50 mg r-TPA; one day later bolus of 1 million IU urokinase followed by 100,000 IU/h) a new thromboembolus was seen by TOE to straddle the pulmonary artery bifurcation. After the urokinase dosage had been raised to 200,000 IU/h TOE on the 6th day no longer showed the embolus and documented a reduction in right-heart dilatation associated with improved haemodynamics. CONCLUSION: TOE is an ideal method for the rapid diagnosis and for monitoring the response to treatment of fulminant pulmonary arterial embolism. As it can also diagnose thromboembolism without significant haemodynamic consequences it is possible to adjust fibrinolytic treatment accordingly.

Acute Disease↗
PubMed1996

[Long term course over 10 years after balloon dilatation in stable and unstable angina pectoris].

OBJECTIVE: To assess the cardiac status of patients ten years after percutaneous transluminal coronary artery angioplasty (PTCA). PATIENTS AND METHODS: Data of 534 patients (436 men, 98 women; mean age 53.2 +/- 8 years) in whom a PTCA had been performed between 1983 and 1986 were analysed, based on a questionnaire answered 121 +/- 11 months after the initial procedure. At the time of PTCA 184 patients (35%) had unstable angina, 350 (65%) stable angina. RESULTS: 116 patients (63%) with unstable angina and 164 (47%) with stable angina had at least one cardiac event after the initial PTCA (repeat PTCA, bypass operation, myocardial infarction, death). None of these events occurred in 68 patients (37%) with unstable or in 186 (53%) with stable angina (P < 0.001). After 10 years 196 of the 302 surviving patients with stable angina (65%) and 104 of the 153 surviving patients with unstable angina (68%) were symptom-free. CONCLUSIONS: Ten-year follow-up after PTCA has shown that cardiac events are significantly more frequent in patients who had had unstable angina than in those with stable angina. This difference already develops in the first year post-PTCA, with no increase later. Symptoms are lastingly improved after 10 years in both groups of patients.

Angina Pectoris↗
PubMed1996

Importance of calibration for diameter and area determination by intravascular ultrasound.

BACKGROUND: Intravascular ultrasound (IVUS) permits quantitative assessment of the lumen diameter and area of coronary arteries. The experimental study was performed to evaluate the accuracy of diameter and area measurements. METHODS AND RESULTS: Lumen quantitation (lumen diameter D and cross-sectional area A) in lucite tubes (lumen diameter 2.5 to 5.7 mm, Plexiglas) was performed using a mechanical IVUS system (HP console, 3.5 F catheter, Boston Scientific, 30 MHz). The influence of fluid type (blood, water and saline solution), fluid temperature (20 degrees C/37 degrees C), catheter to catheter variation, gain setting and ultrasound frequency (12, 20 and 30 MHz) was determined. In blood at 20 degrees C there was a constant deviation of the measured diameter from the true luminal diameter of -0.29 +/- -0.04 mm (p < 0.06). In water and saline solution at 20 degrees C the mean deviation from true diameter was -0.21 +/- -0.06 mm (p < 0.06). At 37 degrees C, the deviation in blood was greater than at 20 degrees (-0.34 +/- -0.02 mm) which is > 10% in a 3 mm tube (p < 0.06). Three of the ten catheters tested in water at 20 degrees C underestimated true diameter by more than -0.3 mm. The deviation from true diameter (5 mm tube) with varying gain settings was -0.14 mm to -0.23 mm compared to -0.19 mm at standard settings (p > 0.288). At 12 MHz diameter measured was over-estimated. The error in absolute area estimation increased with increasing diameter tested in blood at 37 degrees C (-1.21 to -2.72 mm2), whereas the relative error ([Measured Area-True Area]/True Area x 100 [%]) was more striking at smaller diameters (up to -25% in the 2.5 mm tube). CONCLUSION: Luminal diameters and areas are underestimated by this particular IVUS system. When IVUS imaging and measurements are made during coronary interventions this error should be taken into account with regard to appropriate sizing of the device and the assessment of the postprocedure result. Because systematic errors might also occur in other IVUS system (not tested in this study), it is advisable to ensure that each system is validated prior to clinical use, especially when exact measurements are required.

Calibration↗
PubMed1996

Quantification of mitral valve stenosis by three-dimensional transesophageal echocardiography.

The aim of this study was the evaluation of the diagnostic potentials of transesophageal 3D- echocardiography in the determination of mitral valve stenosis. 54 patients were investigated by transthoracic and multiplane transesophageal echocardiography. In 41 patients cardiac catheterization was performed. 3D- echocardiographic data acquisition was performed by automatic transducer rotation at 2 degree increments over a span of 180 degrees. The transesophageal probe was linked to an ultrasound unit and to a 3D- workstation capable of ECG- and respiration gated data acquisition, postprocessing and 2D/3D image reconstruction. The mitral valve was visualized in sequential cross-sectional planes out of the 3D data set. The spatial position of the planes was indicated in a reference image. In the cross-sectional plane with the narrowest part of the leaflets the orifice area was measured by planimetry. For topographic information a 3D view down from the top of the left atrium was reconstructed. Measurements were compared to conventional transthoracic planimetry, to Doppler-echocardiographic pressure half time and to invasive data. The mean difference to transthoracic planimetry, pressure half time and to invasive measurements were 0.3 +/- 0.1 cm2, 0.2 +/- 0.1 cm2 and 0.1 +/- 0.1 cm2, respectively. Remarkable differences between the 3D- echocardiographic and the 2D- or Doppler- echocardiographic methods were observed in patients with severe calcification or aortic regurgitation. In 22% of the patients the 3D data set was not of diagnostic quality. New diagnostic information from a 3D view of the mitral valve could be obtained in 69% of the patients. Thus, although image quality is limited, 3D- echocardiography provides new topographic information in mitral valve stenosis. It allows the use of a new quantitative method, by which image plane positioning errors and flow-dependent calculation is avoided.

Adult↗
PubMed1996

Equipment configuration and procedures: preferences for interventional microtherapy.

Magnetic resonance imaging (MRI), computed tomography, and electron beam tomography scanners are built for radiologic diagnosis. With increasing frequency they are being used in the field of interventional Microtherapy to permit transparent visualization of the therapeutic field. Each of these scanners can be combined with endoscopy, fluoroscopy/digital subtraction angiography, and ultrasound units for hybrid imaging techniques as well as with therapeutic systems like lasers or radiofrequency. MRI affords 3D localization without x-ray exposure. Open access and keyhole imaging allow nearly real time guidance of instruments. Minimally invasive techniques using endoscopes and hybrid tomographic guidance result in improved tip tracking of microinstruments and reduced complications. This safer access into the body will lead to interdisciplinary cooperation with the potential for large cost reductions. This report summarizes our experience regarding which of the hybrid imaging suites is best suited for procedures including among others drug instillations, prosthesis (stent) implantation, or microoperations (endoscopic diskectomy/sequestrectomy), and physiological measurements simultaneously.

Diagnostic Imaging↗
PubMed1996

Analysis of interinstitutional observer agreement in interpretation of dobutamine stress echocardiograms.

OBJECTIVES: This study sought to determine the degree of interinstitutional agreement in the interpretation of dobutamine stress echocardiograms. BACKGROUND: Dobutamine stress echocardiography involves subjective interpretation. Consistent methods for acquisition and interpretation are of critical importance for obtaining high interobserver agreement and for facilitating communication of test results. METHODS: Five experienced centers were each asked to submit 30 dobutamine stress echocardiograms (dobutamine up to 40 micrograms/kg body weight per min and atropine up to 1 mg) obtained in patients undergoing coronary angiography. Thus, a total of 150 dobutamine stress echocardiograms were interpreted by each center without knowledge of any other patient data. Left ventricular wall motion was assessed using a 16-segment model but was otherwise not standardized. No patient was excluded because of poor image quality or inadequate stress level. Echocardiographic image quality was assessed using a five-point scale. RESULTS: Angiographically significant coronary artery disease (> or = 50% diameter stenosis) was present in 95 patients (63%). By a majority decision (three or more centers), the sensitivity, specificity and accuracy of dobutamine echocardiography were 76%, 87% and 80%, respectively. Abnormal or normal results of stress echocardiography were agreed on by four or all five of the centers in 73% of patients (mean kappa value 0.37, fair agreement only). Agreement on the left anterior descending artery territory (78%) was similar to that for the combined right coronary artery/left circumflex artery territory (74%), and for specific segments the agreement ranged from 84% to 97% and was highest for the basal anterior segment and lowest for the basal inferior segment. Agreement was higher in patients with no (82%) or three-vessel coronary artery disease (100%) and lower in patients with one- or two-vessel disease (61% and 68%, respectively). Agreement on positivity or negativity of stress test results was 100% for patients with the highest image quality but only 43% for those with the lowest image quality (p = 0.003). CONCLUSIONS: The current heterogeneity in data acquisition and assessment criteria among different centers results in low interinstitutional agreement in interpretation of stress echocardiograms. Agreement is higher in patients with no or advanced coronary artery disease and substantially lower in those with limited echocardiographic image quality. To increase interinstitutional agreement, better standardization of image acquisition and reading criteria of stress echocardiography is recommended.

Cardiotonic Agents↗
PubMed1996

Influence of vessel dilatation on restenosis after successful percutaneous transluminal coronary angioplasty.

The aim of this study was to evaluate the influence of vessel dilation on restenosis after successful percutaneous transluminal coronary angioplasty (PTCA) on the basis of quantitative angiographic analysis. To have the best comparison possible, we restrospectively studied a homogenous series of patients from the early 1980s treated according to a standardized PTCA procedure. The study group consisted of 86 patients with stable angina pectoris and single-vessel disease, all of whom underwent successful PTCA for a short concentric lesion in proximal vessel parts. The overall restenosis rate was 27%. Angiographically measured balloon size remained below specifications. The size of the inflated balloon at the site of minimal lumen diameter averaged 2.6 +/- 0.5 mm, and nominal balloon size was 3.3 +/- 0.4 mm (p < 0.001). In 22 patients with an oversized balloon (mean balloon/artery ratio 1.1 +/- 0.16) the restenosis rate was 5% compared with 34% in the corresponding group (p = 0.02). Minimal lumen diameters that were similar after the procedure (2.4 +/- 0.3 vs 2.3 +/- 0.4, NS) were 2.3 +/- 0.4 mm and 1.8 +/- 0.7 mm, respectively, at follow-up (p = 0.002). Multivariate analysis revealed balloon/vessel size ratio (p < 0.001), postprocedure diameter stenosis (p = 0.02), and percentage diameter increase produced by PTCA (p = 0.04) as independent correlates of the late outcome. Postangioplasty minimal lumen diameter was not related to restenosis. The strongest and most significant predictor of late PTCA outcome both by univariate and multivariate analysis was balloon/vessel size ratio, especially when balloon expansion at the site of minimal lumen diameter was regarded. In patients with continued success at follow-up, the ratio was 0.81 +/- 0.15 compared with 0.60 +/- 0.11 in patients with restenosis (p < 0.001). Our results suggest that the late angiographic outcome of PTCA is strongly influenced by procedural factors. It appears that in a selected group of patients, an increased balloon/artery ratio, supposedly associated with increased vessel wall stretch, favorably affects the restenosis process.

Aged↗
PubMed1996

The aorta. Aortic aneurysm, trauma, and dissection.

Because of the close relationship between the esophagus and the aorta, multiplane transesophageal echocardiography provides an excellent way to view the thoracic aorta. In this article, clinical features of aortic aneurysm, trauma, and aortic dissection are described, as is the potential use of transesophageal echocardiography in the assessment of these entities.

Aortic Dissection↗