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Biomedical subjects

R Erbel

Publications and source records attributed to R Erbel.

At least 19 recordsLinked to original sources
PubMed1992

Classification of morphologic effects of percutaneous transluminal coronary angioplasty assessed by intravascular ultrasound.

The aim of this study was the assessment and classification of the morphologic effects of percutaneous transluminal angioplasty (PTCA) by intravascular ultrasound (IU). Fifty-eight patients were examined immediately after PTCA with a 4.8Fr, 20 MHz rotational tip IU system. In 10 patients (17%), IU images could not be analyzed due to failure of the imaging system or poor image quality. In 48 patients (83%; 40 men and 8 women, aged 55 +/- 9 years), IU images of 48 PTCA segments, as well as 41 distal and 44 proximal sites, were analyzed. The left anterior descending artery was studied in 30 patients, the right coronary artery in 17 and the left main coronary artery in 1. Calcium was present in 32 of 48 PTCA segments (67%). Plaque morphology was concentric in 18 patients (38%) and eccentric in 30 (62%). Seven distinct morphologic patterns were observed. In concentric plaques, plaque compression without significant wall alterations (type 1) was found in 2 patients (4%), superficial tears within the plaque (type 2) in 1 (2%) and deep tears (type 3) in 8 (17%). Deep tearing associated with submedial or subintimal dissection (type 4) was found in 2 patients (4%). Dissection between plaque and vessel wall without noticeable intimal tearing (type 5) was the most common morphology (n = 15; 31%) and occurred in concentric and eccentric plaques. In eccentric plaques, no significant tearing of the plaque (type 6) was found in 6 patients (13%), and tearing of the plaque close to its base with dissection (type 7) in 14 (29%).(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1992

[Coronary vascular stent implantation--experiences with the first 100 implants].

Coronary stent implantation was performed for blocking elastin recoil, reducing acute complications and restenosis. In 89 (95%) of 91 patients successful stent implantation was possible. No stent embolization occurred. Coronary luminal diameter measured 1.05 +/- 0.57 before PTCA and 1.9 +/- 0.2 mm post PTCA. After stent implantation mean diameter of the coronary artery measured 3.05 +/- 0.2 mm, with a balloon diameter of 3.0. Thus, elastic recoil is nearly completely blocked. In 28 (31%) of 91 patients stent implantation was performed for acute symptomatic dissection in 27 patients and occlusion in one patient. Stent delivery was successful in all. There was no acute occlusion, one acute thrombosis which could be treated with urokinase, no Q-wave-infarct, 4 (14%) non-Q-wave-infarcts and 14 (20%) CK-elevations without ECG changes. Coronary bypass surgery was necessary in 2 patients on an elective base during follow-up. In 72 (90%) of 80 patients follow-up coronary angiograms after 4 to 6 months were performed. Restenosis rate measured 21% overall, 14% for single stent, 60% for multiple stent implantation, and 14% in bail-out situations. Subacute thrombosis occurred in 10 (12%) of 89 patients, 7 (70%) of 10 events after bail-out stenting. Recanalization by thrombolytic and/or PTCA was possible in 9/10 patients. By improving monitoring of anticoagulation, the subacute thrombosis rate could be reduced to 3% even in bail-out situations. Bleeding complication occurred in 10% of the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Long-term follow-up of thrombolytic treatment of acute infarct in combination with acute and elective revascularization].

From March 1983 to June 1986 in 206 patients with acute transmural myocardial infarction, combined intravenous and intracoronary therapy with streptokinase was initiated. After intravenous thrombolysis and randomization in two groups we performed a coronary angiography with selective intracoronary lysis. Infarct related vessels still occluded after intracoronary streptokinase application were opened mechanically in group I. In group II we performed additionally a percutaneous transluminal coronary angioplasty (PTCA) after mechanical recanalisation (occluded vessels) or after thrombolysis (open vessels). In 85 of 87 cases in group II, PTCA could be performed in the acute phase. Elective PTCA was performed in 22 patients of group I (21%) and in nine patients of group II (9%). Up to five years after myocardial infarction, coronary artery bypass grafting (CABG) was necessary in 22 patients (21%) of group I and in 23 patients (22%) of group II. Within four weeks after infarction CABG was performed in 32% and 17% of group I and II respectively. The six-year survival rate was 78% in group I and 82% in group II. Taken all patients together, the six-year survival rate was significantly higher (p = 0.002) for those with early reperfusion (less than or equal to 3.5 h). The survival rates of CABG-patients, PTCA-patients and patients without reperfusion were 91%, 74% and 65% respectively. Streptokinase thrombolysis results, combined with acute or elective PTCA and/or coronary bypass surgery, in a high six-year survival rate after acute transmural myocardial infarction. This rate is about 20% higher than ten years ago.

Angioplasty, Balloon, Coronary↗
PubMed1992

Percutaneous transluminal coronary rotary ablation with Rotablator (European experience).

This study reports the results from 3 European centers using rotary ablation with Rotablator, a device that is inserted into the coronary artery and removes atheroma by grinding it into millions of tiny fragments. Rotary ablation was performed in 129 patients. Primary success (reduction in percent luminal narrowing greater than 20%, residual stenosis less than 50%, without complications) was achieved by rotary angioplasty alone in 73 patients (57%). An additional 38 patients (29%) had successful adjunctive balloon angioplasty. Thus primary success was achieved in 111 patients (86%) at the end of the procedure. Acute occlusion occurred in 10 patients (7.7%). Recanalization was achieved by balloon angioplasty in 7: urgent bypass grafting was undertaken in 2. Q-wave and non-Q-wave myocardial infarction occurred in 3 and 7 patients, respectively. No deaths occurred. Follow-up angiography was performed in 74 patients (60%). Restenosis, defined as the recurrence of significant luminal narrowing (greater than 50%) occurred in 17 of 37 patients (46%) who underwent rotary ablation alone, and 11 of 37 patients (30%) who had adjunctive balloon angioplasty. The overall angiographic restenosis rate was 37.8%. In conclusion, rotary ablation is technically feasible, and relatively safe in the coronary circulation. The low primary success rate reflects the limited size of the device, which can be introduced through available guiding catheters, and limits the use of rotary ablation as a stand-alone procedure to lesions in small arteries or in distal locations. No reduction in restenosis was seen, but the role of this device combined with balloon angioplasty in larger arteries needs to be further defined.

Adult↗
PubMed1992

Echocardiographic and angiographic evaluation of left ventricular function during percutaneous transluminal aortic valvuloplasty.

Transesophageal echocardiography was used to study the effect of the balloon inflation on left ventricular function in 20 patients with critical aortic stenosis undergoing balloon valvuloplasty. Balloon inflation caused an increase of end-diastolic (15% to 34%) and end-systolic (57% to 72%) left ventricular volume. Left ventricular wall stress increased from 30 +/- 10 x 10(3) dyn/cm2 at diastole and 121 +/- 40 x 10(3) dyn/cm2 at systole to 44 +/- 11 x 10(3) dyn/cm2 and 191 +/- 55 x 10(3) dyn/cm2, respectively, when the balloon was inflated (P less than 0.05). Turbulent regurgitant jet across the mitral valve increased from 15 +/- 2% to 25 +/- 3% during balloon inflation (P less than 0.01). Continued monitoring of left ventricular function after balloon deflation demonstrated prolonged enlargement of left ventricular volumes. Our data show that balloon inflation causes an increase of left ventricular volume and impairment of contraction. Increase of left ventricular wall stress--associated with a reduction of coronary blood flow, due to lower aortic pressure--could result in ischemic myocardial injury.

Aged↗
PubMed1992

High-speed rotational angioplasty-induced echo contrast in vivo and in vitro optical analysis.

High-speed rotational angioplasty is being evaluated as an alternative interventional device for the endovascular treatment of chronic coronary occlusions. It has been postulated that this type of angioplasty device may produce particulate debris or cavitations that induce myocardial ischemia. To determine the clinical presence of myocardial ischemia during rotational angioplasty, echocardiographic monitoring for wall motion abnormalities was performed in 9 patients undergoing rotational atheroablation using the Auth Rotablator for 10-sec intervals at 150,000 and 170,000 rpm. No wall motion abnormalities were detected in 5 patients evaluated with transesophageal echocardiography or in 4 patients monitored transthoracically, although AV block developed in one patient. Video intensitometry of the myocardial contrast effect for rotation times ranging from 3 to 20 sec found transient contrast enhancement of the myocardium supplied by the treated vessel. Intensity varied over time with half-time decay between 5.6 and 40 sec, indicating the likelihood of microcavitation. An in vitro model was constructed to measure the cavitation potential of the Auth Rotablator. A burr of 1.25 mm diameter rotating at 160,000 rpm achieves a velocity in excess of the 14.7 m/sec critical cavitation velocity. Testing the device in fresh human blood and distilled water produced microcavitations responsible for the enhanced echo effect, with the intensity and longevity of cavitation more pronounced in blood and proportional to the rotation time and speed. The mean size of the microcavitation bubbles in water was 90 +/- 33 (52-145) microns measured from photographs taken with a copper vapour laser emitting light pulses of 50 nsec duration as light source. The mean velocity of bubbles was found to be 0.62 +/- 0.30 ranging from 0.23 to 1.04 m/sec. It was measured via the motion of the bubbles during 5 laser pulses within 800 nsec. Clearly, microcavitations are associated with enhanced myocardial echo contrast effect.

Angioplasty, Balloon, Coronary↗
PubMed1992

Effects of ciprostene on restenosis rate during therapeutic transluminal coronary angioplasty.

Ciprostene, a chemically stable prostacyclin analog was studied for its effects on restenosis in patients with coronary artery disease undergoing therapeutic percutaneous transluminal coronary angioplasty (PTCA). In a double-blind, randomized trial 32 patients were randomized to receive either ciprostene or the respective placebo. The infusion started intracoronarily at a rate of 40 ng/kg/min 20 min before introduction of the balloon catheter into the coronary artery. Thereafter infusion was continued intravenously for 36 hours at a rate of 120 ng/kg/min and a tapering off period until 48 hours. The quantitative analyses of the degree of coronary artery stenoses on the angiographic films before PTCA, after PTCA and after 6 month of follow-up was performed in 24 patients available. In patients receiving placebo (n = 12) coronary artery stenoses was 81 +/- 3% before PTCA and was reduced to 34 +/- 3% by angioplasty. At the 6 month follow up angiography stenoses diameter was measured as 63 +/- 8%, being not significantly different from the % stenoses before PTCA. In contrast, coronary artery stenoses in patients receiving ciprostene (n = 12) measured 83 +/- 3% before PTCA, 31 +/- 4% after PTCA and 55 +/- 9% at 6 month, being still significantly different from pre-PTCA value (P less than 0.05). When patients were characterized according to their clinical status, these differences were accounted for by patients with unstable angina receiving ciprostene. Ciprostene seems to reduce restenosis 6 month after coronary angioplasty in patients with unstable angina. The infusion rate of 40 ng/kg/min i.c. followed by 120 ng/kg/min i.v. was tolerated well, although the incidence of catheter associated bleeding was increased.

Adult↗
PubMed1992

Spontaneous echo contrast imaging in infective endocarditis: a predictor of complications?

Infective endocarditis is associated with significant morbidity and mortality. Valvular destruction and congestive heart failure are more common in patients with echocardiographically detectable vegetations. In addition, spontaneous platelet aggregation is increased when vegetations are present on cardiac valves. The aim of the study was to assess the prognostic value of spontaneous echo contrast (SEC) imaging, as SEC is supposed to reflect red blood cell aggregates stimulated by platelet activity. We studied 293 patients with clinical signs of infective endocarditis. Vegetations, attached to the aortic or mitral valve, were found in 130 patients (44.4%) who were followed for a mean period of 12 months. In 34 of these 130 patients (26.2%) SEC was imaged during the initial transesophageal echocardiographic examination. In these patients SEC indicated a prolonged healing of infective endocarditis with a specificity of 91.2%, a sensitivity of 77.3%, a positive accuracy of 77.3%, a negative accuracy of 74.3%. Multivariate analysis revealed that SEC is a risk factor for valve replacement (p less than 0.001) and for embolic events (p less than 0.001), less for mortality (p less than 0.01), and lowest for abscess formation (p less than 0.05). The dose of ADP to induce half-maximal platelet aggregation was significantly lower in patients with SEC (0.71 +/- 0.15 microliters) than without SEC (1.05 +/- 0.12 microliters; p less than 0.05), implying an increased spontaneous platelet aggregation in the presence of SEC. Our data provide evidence that systemically activated coagulation plays an important role in infective endocarditis. SEC, the echocardiographic implication of an increased platelet aggregation, predicts complications such as thromboembolic events and the need for surgery and is closely related to the prolonged healing period of infective endocarditis. In addition to demonstrating vegetations, transesophageal echocardiography provides information helpful in assigning patients to a high-risk subgroup. Transesophageal echocardiography may play an important role in assessing the clinical outcome of these patients.

Adult↗
PubMed1992

Monitoring prothrombin fragment 1 + 2 during initiation of oral anticoagulant therapy after intracoronary stenting.

Patients with intracoronary stent implantation are treated with aggressive anticoagulant and antiplatelet therapy consisting of high-dose heparin, phenprocoumon, acetylsalicylic acid, dipyridamole, and the infusion of dextran to prevent a subacute thrombotic occlusion of the stented segment. In an effort to optimize this treatment by reducing both imminent bleeding complications and subacute thrombotic occlusion, the concentrations of prothrombin fragment 1 + 2 (F 1 + 2) were determined after intracoronary Palmaz-Schatz stent implantation in 19 consecutive patients. The F 1 + 2 concentrations after stent implantation and before the initiation of oral anticoagulant therapy (OAT) were 0.35 nm/l and 0.25-0.53 nm/l (median and 25th-75th percentile), versus 0.74 nm/l and 0.52-0.78 nm/l, in healthy subjects and 0.61 nm/l and 0.30-1.02 nm/l in 15 patients with ongoing proximal DVT. Nine days after initiation of OAT, F 1 + 2 concentrations in both patient groups had not yet reached levels observed in patients with OAT in the stable state (0.16 nm/l, 0.12-0.26 nm/l; n = 76; P less than 0.0001 compared with healthy subjects; INR 2.0-4.5). Despite an INR greater than 2.0, accompanying heparinization was terminated on day 9. In two stented patients a minor bleeding complication arose after the removal of the arterial catheter. Subacute thrombotic occlusions were not observed. Since F 1 + 2 concentrations did not exceed the upper limit of normal range (1.11 nm/l) in any of the 19 patients, the therapeutic regimen was not changed. Monitoring F 1 + 2 may thus be helpful in introducing a more individual treatment if aggressive anticoagulation has to be performed.

Administration, Oral↗
PubMed1992

Relative sensitivity of four noninvasive methods in assessing systolic cardiovascular effects of isoproterenol in healthy volunteers.

STUDY OBJECTIVE: The study was performed to evaluate the relative sensitivity of various noninvasive methods to detect and describe the systolic cardiovascular effects of stepwise increasing doses of isoproterenol: two-dimensional left ventricular echocardiography (main variable, ejection fraction), ACVF (attenuation compensated volume flow)--dual-beam Doppler echoaortography (time-averaged mean velocity), electrical impedance cardiography [(dZ/dtmax)/RZ index], and systolic time intervals from mechanocardiography (PEP and QS2c). METHODS: Isoproterenol was administered by constant rate intravenous infusion in consecutive steps of 0.1, 0.2, 0.4, 0.75, and 1.5 micrograms/min (each for 15 minutes). Saline control infusions were given in analog fashion. The treatments (isoproterenol and saline solution) were administered in a period-balanced two-way crossover design with randomly allocated sequences. The subjects, observers, and analysts were blinded to the treatment protocol. Study subjects were 10 healthy male volunteers (age range, 23 to 31 years; mean age, 26.6 years). RESULTS: Compared with saline solution, isoproterenol caused a dose-related increase in ejection fraction, (dz/dt)/RZ index, and time-averaged mean velocity and a dose-related shortening of PEP and QS2c. The responses are congruent with an enhancement of cardiac systolic performance caused by a positive inotropic stimulation and an afterload reduction ("inodilatory" response). The effects on systolic time intervals reached statistical significance (alpha = 0.05) at the first isoproterenol dose step, the effects on the impedance cardiography and the Doppler echoaortography variables reached statistical significance at the second dose step, and the effects on the two-dimensional echocardiography reached statistical significance at the third dose step. CONCLUSIONS: All methods allowed to detect isoproterenol-related changes. Systolic time intervals were the most sensitive, followed by impedance cardiography, ACVF--dual-beam Doppler echoaortography, and two-dimensional echocardiography. The practical convenience and high sensitivity of the systolic time intervals makes them suitable to evaluate investigational systolic inodilatory changes in humans.

Adult↗
PubMed1992

[Percutaneous sonographic angioplasty. Initial experimental results].

Aim of the present study was to examine in vitro the effects of a new ultrasound catheter system on atherosclerotic and normal vessels before employing the system in humans. 141 attempts were made on 32 vascular preparations obtained at autopsy. The vessels were opened longitudinally within 24 hours of death, dilated with gelatine and were then "treated" in a waterbath using varying degrees of pressure, angle of incidence, sound intensity and duration of sound. Macroscopic and histological examinations of the preparation showed no morphological change in normal vessels except evidence of pressure by the catheter. In particular, there were no perforations of the vessel wall. In atherosclerotic segments there was significant reduction in the size of plaques following treatment.

Angioplasty, Balloon↗
PubMed1992

[Measurement error estimation in MR tomographic volumetry of the left ventricle with the multisection technic].

A multi-slice technique for MRT measurements of the left ventricular volume is much faster than the use of single-slice methods and is therefore better tolerated, leaving time for additional measurements. The end-diastolic left ventricular volume can be reliably measured by this method (123.3 +/- 13.5 ml vs. 124.1 +/- ml). The end-systolic volume is consistently overestimated by 23.7 +/- 18.3% compared with the reference value obtained by single slice measurements (47.9 +/- 8.9 ml vs 39.1 +/- 7.9 ml). Correspondingly, stroke volume and ejection fraction is underestimated on average by 10.6 +/- 9.7% and 10.6 +/- 7.6% respectively).

Adult↗
PubMed1992

Arrhythmia profile in acromegaly.

In a controlled study, the cardiac involvement and arrhythmia profile of 32 patients with acromegaly were correlated with endocrine parameters (somatomedine C, growth hormone), clinical score and duration of the disease. Data were compared with those of 50 controls free of cardiac disease. Stress ECG, 24 h Holter monitoring and echocardiography were performed. Supraventricular premature complexes occurred no more often in acromegalics than in controls. Both prevalence and severity of ventricular arrhythmia, however, were significantly higher in patients compared to controls (P less than 0.01). 15/32 (48%) acromegalic patients had complex ventricular arrhythmias (Lown III-IV) as compared with 6/50 (12%) normal subjects (P less than 0.01). Repetitive ventricular arrhythmias (Lown IV a/b) occurred in 10/32 (31%) patients, but only in 4/50 (8%) controls (P less than 0.01). Furthermore, the frequency of ventricular premature complexes increased with duration of acromegaly (P less than 0.01). No correlation was found between the severity of ventricular arrhythmia and hormone levels. Left ventricular muscle mass was significantly increased (285 +/- 139 g, P less than 0.02) due to concentric hypertrophy. Severity of ventricular arrhythmias correlated with left ventricular mass and with clinical activity score (P less than 0.01). Thus, compared to controls, acromegalic patients show more frequent and complex ventricular arrhythmias and left ventricular hypertrophy. Duration of the disease rather than hormone levels seems to be relevant for these pathological changes.

Acromegaly↗
PubMed1992

Clinical relevance of vegetation localization by transoesophageal echocardiography in infective endocarditis.

Infective endocarditis is associated with significant morbidity and mortality, with valvular destruction and congestive heart failure being more common in patients with echocardiographically discernible vegetations. The transoesophageal approach affords consistently high quality images with excellent structural resolution. Two-hundred and eighty-one patients with clinically suspected infective endocarditis were studied, to evaluate the prognostic value of ascertaining the site of vegetations. Among them were 118 patients with vegetations attached to the aortic or mitral valve. These patients were followed for a mean period of 14 months. Mitral valve vegetations were associated with a significantly higher incidence of embolic events than vegetations on aortic valves (25% vs 9.7%). The incidence of abscess formation was higher in aortic than in mitral valve endocarditis (6% vs 0%), as were the need for surgical intervention (11% vs 5.5%) and mortality (1.6% vs 0%) respectively). Bivalvular endocarditis was associated with an increased rate of complications: embolism (50%), abscess formation (15%), surgery (35%) and mortality (10%). By multivariate analysis, echocardiographically accessible risk factors for subsequent embolism were a vegetation size of more than 10 mm and mitral valve involvement. Risk factors associated with in-hospital fatality were embolism, a vegetation size of more than 10 mm, and Staphylococcus aureus infection. Our data suggest that the site influences both the rate and the type of complications. Precise echocardiographic visualization of vegetations helps to stratify patients into a high-risk sub-group, perhaps warranting early prophylactic surgical intervention. Transoesophageal echocardiography may play an important role in assessing the clinical outcome for these patients.

Abscess↗
PubMed1992

Acute hemodynamic effects of nicorandil in coronary artery disease.

Nicorandil is a potent vasodilator with antianginal and anti-ischemic properties that acts on both the coronary and the peripheral vascular bed. Because of its dual vasodilatory mechanisms mediated by an increase in cyclic GMP similar to that of nitrates and by a selective increase in the K+ conductance of the smooth muscle cell membrane, nicorandil unloads the right and left ventricles at rest and during exercise. Thus, compared with the classic nitrates, nicorandil is a more balanced vasodilator, i.e., it affects not only the venous capacitance vessels (as predominantly affected by nitrates) but also the arterial resistance vessels. In clinical pharmacologic trials, nicorandil has been administered intravenously (2 to approximately 14 mg) as well as sublingually and orally in single doses of 10-60 mg. In patients with coronary artery disease and impaired left ventricular function, the decrease in preload resulted in a significant improvement of cardiac output. Depending on the doses applied and the patient populations studied, observed decreases in systemic blood pressure were consistent with decreases in peripheral vascular resistance. The effect on heart rate was small, and no influence on atrioventricular conduction could be detected. Nicorandil enhanced exercise capacity in patients with ischemic heart disease. This benefit can be attributed to the reduction in loading of the right and left ventricle as well as to an improvement of regional wall motion abnormalities secondary to the coronary dilatory properties of the drug. Nicorandil appears to be a valuable additive to the antianginal and anti-ischemic management of coronary artery disease.

Animals↗