Biomedical subjects

Tamás Simor

Publications and source records attributed to Tamás Simor.

10 recordsLinked to original sources

PubMed2006

Gd(ABE-DTTA), a novel contrast agent, at the MRI-effective dose shows absence of deleterious physiological effects in dogs.

The physiological effects of a novel MRI contrast agent, Gd(ABE-DTTA), were investigated in dogs, monitoring parameters in blood samples. Each animal (n = 8 in the short-term, n = 4 in the long-term group) underwent isoflurane anesthesia followed by the generation of myocardial infarction and received a contrast agent at the MRI effective dose. Blood samples were collected 24 and 48 h, and 7, 14, 28, 35, 49 and 56 days after contrast agent administration. No significant changes exceeding the normal range were detected in any of the investigated parameters except in alanine aminotransferase (ALT). ALT enzyme activity increased in the short-term group 24 and 48 h after agent administration as expected from the effect of isoflurane anesthesia. Between days 7 and 56 no elevation in ALT was observed. In dogs no substantial short- or long-term effect was observed on the investigated, physiological parameters after Gd(ABE-DTTA) administration at the MRI effective dose.

Alanine Transaminase↗

PubMed2006

[Quantification of right and left ventricular function with magnetic resonance imaging after Senning operation for complete transposition of the great arteries].

INTRODUCTION: The different non-invasive examinations do not result in unambigous results about the long-term determination of right ventricular function providing systemic circulation in children with transposition of the great arteries operated with Senning procedure. AIM: The goal of study was to determine the application of MRI for the observation of right and left ventricular morphology and function, for the recognition of the progression of the disease, and for the necessity of reoperation. METHODS: The authors have observed the morphology and function of the right and left ventricule by ECG triggered short axis MR pictures. For the analysis of MR pictures MASS 5.0 software was used. Authors have determined the end systolic and end diastolic volume, the ejection fraction, the mass, and the stroke volume of the right ventricule, the end systolic and end diastolic volume, ejection fraction, the mass, and the stroke volume of the left ventricle, and the shunt volume. The values of these data corrected to body mass have been calculated. PATIENTS: 176 Senning operations took place between 1980 and 1996. MRI exploration at 21 of the 118 analyzed patients were carried out. RESULTS: The right ventricular ejection fraction value at Senning operated patients is significantly different (49 +/- 9% vs. 70 +/- 4%) from those of healthy children (P < 0.01). Right ventricular stroke volume/m2 and right ventricular end systolic volume/m2 were significantly different compared to normal (43 +/- 10 ml/m2 vs. 48 +/- 7 ml/mn and 46 +/- 16 ml/m2 vs. 21 +/- 5 ml/m2, p < 0.05). Authors found also significant differences in left ventricular ejection fraction in Senning patients as compared to normal (60 +/- 9% vs. 70 +/- 6%, p < 0.01). CONCLUSION: MRI, which is a reliable method of objective determination of right ventricular function, became an available method in Hungary. According to the results, authors might presume that the development of right ventricular dysfunction is expected even among Senning operated children without clinical symptoms, so more frequent control is required. The pathological left ventricular parameters may be explained by ventricular interactions. Authors find MRI an important part of the complex follow-up protocol of Senning operations. MRI data extended by results of other non-invasive explorations are appropriate for the follow-up of right ventricular dysfunction.

Cardiac Surgical Procedures↗

PubMed2006

[Experiences with the first, Hungarian autologous bone marrow cell transplantation in acute myocardial infarction].

Intracoronary transfer of autologous bone marrow cells promotes recovery of left ventricular systolic function in patients with acute myocardial infarction. Although the exact mechanisms of stem cell therapy are still intensely debated, the concept of stem cell therapy has already been introduced into the clinical practice--at least as an adjunctive therapy in clinical trials. In this article the authors report their experiences about the first Hungarian phase I. trial in bone marrow stem cell transplantation after acute myocardial infarction. So far, four patients with acute ST elevation myocardial infarction were eligible and recruited into the trial. All patients received purified, autologous bone marrow stem cells into the re-opened infarct related artery via a second catheterisation. The primary end point of the study is ejection fraction, which is measured by cardiac MRI at the beginning and 6 months after recruitment. So far, cell transfer did not increase the risk of adverse clinical events or proarrhythmic effects.

Angina Pectoris↗

PubMed2006

Percent infarct mapping: an R1-map-based CE-MRI method for determining myocardial viability distribution.

Viability detection is crucial for the management of myocardial infarction (MI). Signal intensity (SI)-based MRI methods may overestimate infarct size in vivo. In contrast to SI, the longitudinal relaxation-rate enhancement (DeltaR1) is an intrinsic parameter that is linearly proportional to the concentration of contrast agent (CA). Determining DeltaR1 in the presence of an infarct-avid persistent CA (PCA) allows determination of the per-voxel percentage of infarcted tissue. Introduced here is a DeltaR1-based CE-MRI method, termed percent infarct mapping (PIM), for quantifying myocardial viability following delayed PCA accumulation. In a canine MI model (N=6), PIMs were generated using a persistent CA (PCA) and validated using triphenyltetrazolium-chloride (TTC) histochemistry. Voxel-by-voxel R1 maps of the entire left ventricle (LV) were generated 24 and 48 hr after PCA administration using inversion recovery (IR) with multiple inversion times (TIs). PI values were calculated voxel by voxel. Significant correlations (P<0.01, R=0.97) were obtained for PI per slice (PIS) determined using PIM vs. corresponding TTC-based values. Median deviations of PIS with PIM from that with TTC were only 1.01% and -0.53%, at 24 hr and 48 hr. Median deviations from the true infarction fraction (IF) were 1.23% and 0.49% of LV at 24 hr and 48 hr, respectively. No significant difference was found between PIM24 hr and PIM48 hr. DeltaR1-based PIM is an accurate and reproducible method for quantifying myocardial viability distribution, and thus enhances the clinical utility of CE-MRI.

Algorithms↗

PubMed2006

Erdheim-Chester's disease of the heart: a diagnostic conundrum and collision with the same mass in the orbit.

Erdheim-Chester's disease is a rare multisystem xanthogranulomatosis, afflicting the skeletal system with the occasional involvement of soft tissues. We delineate an unusual case of a cardiac variant of Erdheim-Chester's disease presenting with pericardial effusion and as a collision with a synchronous orbital manifestation. We describe our diagnostic pathway and propose a novel treatment option involving nonsteroidal anti-inflammatory drugs. The role of cyclo-oxygenase in the disease process and inhibition thereof by NSAIDs is hypothesized and discussed.

Celecoxib↗

PubMed2005

[Postural tachycardia syndrome].

Erect posture could be a source of diverse chronic symptoms usually referred as orthostasis intolerance. Increasing number of patients suffering from orthostatic syndromes is recognized. Characterization and distinction of these orthostatic syndromes are based on the clinical presentation; including the typical history of orthostasis intolerance, and the unique hemodynamic responses on assuming upright posture. The diagnosis of postural tachycardia syndrome (POTS) requires orthostatic heart rate acceleration in excess of 120 beat/min, or an absolute increase of > or = 30 beat/min, in the absence of significant orthostatic hypotension. Subjects with POTS often exhibit more widespread symptoms of autonomic dysregulation. The diagnosis of inappropriate sinus tachycardia (IST) is based on the presence of resting tachycardia defined by pulse rate of > or = 100 beat/min, or a heart rate acceleration to same range in response to minimal stress, or activity. For the illustration of the difficulties in differentiation between these overlapping syndromes the authors present a case with POTS. The unique features of the presented case are the extreme orthostatic tachycardia (170/min), and the unexpected therapeutic effect of sinus node radiofrequency modification. We suggest a relationship between the peak orthostatic heart rate and the therapeutic value of sinus node modification.

Adult↗

PubMed2005

[Correlation of B-type natriuretic peptide (NT-proBNP) levels and conventional and tissue Doppler echocardiographic parameters of left ventricular diastolic function in patients with hypertrophic cardiomyopathy].

INTRODUCTION: Preload-independent pulsed tissue Doppler echocardiography (TDI) and conventional pulsed Doppler echocardiography were used to assess the global left ventricular diastolic function in patients with hypertrophic cardiomyopathy (HCM). Levels of B-type natriuretic peptide (BNP) could be elevated in patients with isolated left ventricular diastolic dysfunction. AIM: The study was to investigate the correlation between BNP levels and the parameters measured by conventional echocardiography and TDI in patients with HCM. PATIENTS: 32 consecutive patients with HCM (21 male, 11 female, mean age 47 +/- 14 years) were studied. Inclusion criteria were: normal sinus rhythm; ejection fraction > or = 50%; absence of moderate to severe mitral regurgitation or prosthetic mitral valve. METHODS: In addition to the conventional transmitral flow patterns (E, A, E/A, DT, IVRT) myocardial early (Ea) and late diastolic (Aa) velocities were measured at the lateral and septal border of the mitral annulus by ATL HDI 5000 ultrasound system. Ea/Aa and E/Ea ratios were calculated. NT-proBNP levels were measured by Roche-Elecsys test (immunoassay). Because the distribution of BNP values did not appear to be normal, the values were transformed into a natural logarithm (InBNP). RESULTS: Mean BNP level was 543 +/- 845 pg/ml. BNP levels negatively correlated with lateral Aa values (r = -0.59, p < 0.001). No significant relationship was observed between BNP levels and other echocardiographic parameters. By stepwise multiple linear regression analysis the only significant predictor of InBNP was lateral Aa value, too (r = -0.467, p < 0.05). CONCLUSION: Significant correlation was found between BNP levels and a single TDI parameter characterizing left atrial systolic function, but there was no significant correlation between BNP levels and global left ventricular diastolic function characterized by either conventional echocardiographic or TDI parameters.

Adult↗

PubMed2005

Gd(ABE-DTTA)-enhanced cardiac MRI for the diagnosis of ischemic events in the heart.

PURPOSE: To demonstrate that contrast-enhanced MRI (ceMRI) with the aid of Gd(ABE-DTTA) is able to detect ischemic events in the heart in a canine ischemia/reperfusion (30/40 minutes) model. MATERIALS AND METHODS: ECG-gated, T1-weighted MR image sets (four to five slices each) with three-minute time resolution were collected in transiently LAD-occluded dogs. Following the acquisition of control image sets, ischemia was started by occluding the LAD. Either Gd(ABE-DTTA) (N = 6) or Gd(DTPA) (N = 6) was injected, and imaging was continued for 30 minutes of ischemia and 40 minutes of reperfusion. The contrast agent (CA)-induced MRI signal intensity enhancement (SIE) and contrast were monitored. Microspheres measured myocardial perfusion (MP) to verify areas of ischemia and reperfusion. RESULTS: SIEs of 86% +/- 3% and 97% +/- 3% in nonischemic, and 25% +/- 5% and 29% +/- 8% in ischemic regions were found within three minutes of onset of ischemia with Gd(ABE-DTTA) and Gd(DTPA), respectively. For the rest of the 30 minutes of ischemia, with Gd(ABE-DTTA) SIE of 60% +/- 3% and 25% +/- 5% persisted in the nonischemic and ischemic regions, respectively. With Gd(DTPA), however, SIE in the nonischemic areas decreased rapidly after the first three minutes of ischemia, while SIE in the ischemic areas increased, abolishing contrast. Thus, there was a persistent contrast with Gd(ABE-DTTA) and a short-lived contrast with Gd(DTPA) during ischemia. Furthermore, with Gd(ABE-DTTA) some contrast was still visible in the early reperfusion period. CONCLUSION: Gd(ABE-DTTA) in an ischemia/reperfusion model induces a persistent MRI contrast between regions of normal and ischemic myocardium, and verifies reperfusion. Therefore, it can be used to detect myocardial ischemic events.

Analysis of Variance↗

PubMed2004

Magnetic resonance imaging-based biventricular pacemaker upgrade.

This report describes a patient with drug refractory severe chronic ischemic heart failure, atrial fibrillation with bradycardia, and left bundle branch block who had a failed implantation of a biventricular pacemaker because of a high left ventricular pacing threshold. VVI pacemaker implantation had not improved the patient's condition. MRI-guided biventricular pacemaker upgrade had been performed with a left ventricular epicardial lead at the lateral region where a 4-mm thickening during systole had been proven. After 6 months of effective resynchronization, the patient's functional class improved to NYHA II without further need of hospitalization.

Atrial Fibrillation↗

PubMed2004

[Treatment of atrial fibrillation with intraoperative radiofrequency ablation in one stage with valvular surgery].

Atrial fibrillation is the most frequent chronic arrhythmia, with significant cardiovascular morbidity and mortality risk. Poor remission rate with medical treatment and the outstanding efficacy of Cox-maze procedure inspired the less invasive intraoperative radiofrequency ablation therapy in patients undergoing open heart surgery. In June 2003 the first maze procedure in Hungary with the Medtronic Cardioblate surgical ablation system, with mitral and tricuspid valvuloplasty in a patient suffering from mitral and tricuspid insufficiency with paroxysmal atrial fibrillation, was performed in our institution. After 8 months the patient is in sinus rhythm and is free of complaints.

Atrial Fibrillation↗