Search PubMed⌕ Search

Biomedical subjects

G Breithardt

Publications and source records attributed to G Breithardt.

At least 73 records · Page 4Linked to original sources
PubMed2001

Brugada syndrome and supraventricular tachyarrhythmias: a novel association?

INTRODUCTION: The Brugada syndrome is a distinct form of idiopathic ventricular fibrillation characterized by a unique ECG pattern consisting of a right bundle branch block-like aspect and ST segment elevation in leads V1 to V3. As a high induction rate of ventricular tachyarrhythmias has been reported in Brugada syndrome, we hypothesized that this also may be true for supraventricular tachycardias in these patients. METHODS AND RESULTS: Between January 1995 and December 2000, we identified 35 consecutive patients with Brugada syndrome; 26 had a history of cardiac arrest or syncope and 9 were asymptomatic. All patients underwent electrophysiologic study, including an atrial and ventricular stimulation protocol. Ten patients (29%) were found to have supraventricular tachyarrhythmias (SVT) in addition to the Brugada syndrome. These 10 patients presented with aborted sudden cardiac death (n = 3) and/or a family history of sudden cardiac death (n = 4), syncope (n = 4), or primarily with a Brugada typical ECG, a positive family history, and palpitations (n = 2). Eight of them underwent genetic testing, but only 1 had a mutation in the SCN5A gene. In 6 patients, an AV nodal reentrant tachycardia was easily and reproducibly inducible. Two patients had clinical documented and inducible episodes of an atrial tachycardia (1 in addition to an AV nodal reentrant tachycardia). One patient had paroxysmal atrial fibrillation alternating with sinus rhythm, and 2 patients with accessory pathways were identified. CONCLUSION: This is the first description of an association of the Brugada syndrome with SVT. Thus, the arrhythmogenic substrate in Brugada syndrome may not be restricted to the ventricular level. Palpitations in this syndrome should raise the possibility of SVT. Conversely, in patients with SVT and aborted sudden cardiac death or syncope not related to SVT, the Brugada syndrome should be considered a possible additional electrophysiologic abnormality.

Adult↗
PubMed2001

Defibrillation efficacy comparing a subcutaneous array electrode versus an "active can" implantable cardioverter defibrillator and a subcutaneous array electrode in addition to an "active can" implantable cardioverter defibrillator: results from active can versus array trials I and II.

INTRODUCTION: Placement of implantable cardioverter defibrillators (ICDs) has been simplified by using the shell of a pectorally implanted ICD as a defibrillation electrode in combination with an endocardial right ventricular defibrillation lead. However, a sufficiently low defibrillation threshold (DFT) cannot be obtained in a few patients. Therefore, alternative approaches were systematically tested in the Active Can versus Array Trial (ACAT). METHODS AND RESULTS: In the first of two prospective randomized studies, the DFT of a subcutaneous left dorsolateral array anode introduced from a pectoral incision was compared to that of a standard active can anode in 68 patients. Intraoperatively, the DFT was determined twice in each patient using either the active can or, in patients with a subcutaneous array lead, once with all three fingers and once omitting the middle finger of the array. The second prospective randomized study included 40 patients. DFT also was determined twice in each patient using an active can in a left pectoral position as anode alone and combined with a left dorsolateral array electrode with two fingers. In ACAT I, stored energy at DFT decreased from 13.1+/-7.7 J (active can) to 9.6+/-6.1 J (three-finger array lead) (P = 0.04), impedance decreased from 53+/-8 ohms to 40+/-6 ohms (P < 0.0001). Omitting the middle finger of the array lead, stored energy at DFT increased by 0.9 J (P = 0.47) and impedance by 2 ohm (P < 0.0001). In ACAT II, DFT and impedance using an active can device were significantly lower when a two-finger array lead was added that decreased stored energy at DFT from 10.1+/-5.2 J to 6.9+/-3.9 J (P = 0.001) and impedance from 56+/-5 1 to 42+/-5 l (P < 0.0001). CONCLUSION: In combination with a right ventricular defibrillation electrode, a left pectoral subcutaneous array lead improves defibrillation efficacy if used instead of, or in addition to, a left pectoral active can ICD device. Implantation of the array lead can be simplified by using two instead of three fingers, without a significant loss of defibrillation efficacy.

Adult↗
PubMed2001

Targeting the slow pathway for atrioventricular nodal reentrant tachycardia: initial results and long-term follow-up in 379 consecutive patients.

OBJECTIVES: This study is designed to examine the immediate and short-term outcomes of patients who have undergone slow pathway ablation/modification for atrioventricular nodal reentrant tachycardia. BACKGROUND: Targeting the slow pathway has emerged as the superior form of treatment for atrioventricular nodal reentrant tachycardia. This technique has been found effective and is associated with a low complication rate. However, little is known of the long-term outcome of patients undergoing this procedure. METHODS: Over a 40-month period the slow pathway was targeted in 379 consecutive patients with proven atrioventricular nodal reentrant tachycardia. The case records of all patients were examined. Accurate follow-up data is available in 96% of patients a mean of 20.6 months after the procedure. RESULTS: The initial success rate was 97%. The incidence of complete heart block was 0.8% and the mean fluoroscopy duration was 27.3 min. The recurrence rate was 6.9%. Age, number of pulses and fluoroscopy time were positively associated with either initial failure or recurrence. A total of 11.3% of patients were still taking antiarrhythmic medication at follow-up. CONCLUSIONS: Targeting the slow pathway is an effective form of treatment for atrioventricular nodal reentrant tachycardia. The technique has a high initial success rate, a low complication rate and a low recurrence rate at long-term follow-up. Slow pathway modification is associated with similar success rates and recurrence rates as slow pathway ablation and may confer theoretical long-term benefits.

Catheter Ablation↗
PubMed2001

Impact of radiofrequency catheter ablation of accessory pathways on the frequency of atrial fibrillation during long-term follow-up; high recurrence rate of atrial fibrillation in patients older than 50 years of age.

AIMS: Atrial fibrillation represents a frequent and potentially life-threatening arrhythmia in patients with accessory atrioventricular pathways. Radiofrequency ablation has become the curative treatment of first choice for these patients. Investigations after successful surgical pathway dissection reported an almost complete elimination of paroxysmal atrial fibrillation. However, there are only a few reports which include a small number of patients undergoing radiofrequency ablation. The purpose of this study was to examine whether successful radiofrequency ablation of accessory pathways prevents the occurrence of paroxysmal atrial fibrillation, and to identify possible predictors of atrial fibrillation recurrence. METHODS AND RESULTS: A total of 116 consecutive patients (mean age 42+/-15 years) with manifest or concealed accessory pathways and documented paroxysmal atrial fibrillation underwent radiofrequency catheter ablation. The patients were reexamined at 6 and 12 months. Long-term follow-up information was obtained by questionnaire and/or by consulting the referring physician. Pathway conduction was abolished in 101 cases (87%). Late follow-up information was obtained from 91 of these 101 patients (90%) with successful ablation with a mean follow-up duration of 23.9+/-12.3 months. During follow-up, 25 of 91 patients (27%) experienced arrhythmias. Recurrent episodes of atrial fibrillation were observed in 18 of these 25 cases (i.e. 20% of the 91 patients). Differences between patients with and without recurrences of atrial fibrillation were examined for age, sex, associated cardiac disease, presence of multiple pathways, pathway location, atrial fibrillation inducibility during the procedure and cycle length of the atrioventricular reentrant tachycardia. Only older age was a significant independent predictor of atrial fibrillation recurrence (P=0.02). Eleven of 31 patients (35%) older than 50 years of age had atrial fibrillation recurrences during follow-up compared to seven of 60 patients (12%) under age 50. The recurrence rate of atrial fibrillation was even higher in patients older than 60 years (6 of 11 patients, i.e. 55%). In comparison, the occurrence rate of atrial fibrillation during follow-up in a control group of 100 consecutive patients with successful accessory pathway ablation, who did not have evidence of paroxysmal atrial fibrillation prior to ablation, was 4% and, thus, significantly lower than in the study group of the 91 patients (P=0.001). CONCLUSIONS: The recurrence rate of paroxysmal atrial fibrillation after successful radiofrequency ablation of accessory pathways shows an age-related increase, being low in patients younger than 50 years of age (12%) and high in the older patients: 35% in patients older than 50 years and 55% in patients older than 60. These results have significant therapeutic implications concerning the decisions on pharmacological therapy after successful ablation in patients older than 50 years. Furthermore, these data will help physicians advise older patients properly about their risk of recurrence of atrial fibrillation after ablation.

Adult↗
PubMed2001

[MRI study of left ventricular function in patients with coronary disease and myocardial dysfunction before and after coronary revascularization].

PURPOSE: To evaluate left ventricular (LV) myocardial function in ten patients with coronary artery disease (CAD) preoperatively and 6 months after coronary bypass grafting (CABG) by cardiac MRI. MATERIAL AND METHODS: Ten patients (mean 65.2 +/- 5.9 years) with angiographically proven CAD and an indication for elective CABG underwent prospective evaluation of global LV function and regional wall motion by Cine-MRI at rest using a multiphase FLASH-2D sequence following regions of interest (ROI)-defined diagnostics of regional myocardial wall motion by means of levocardiography. Within the ROIs a total of 613 LV myocardial segments were analyzed preceding and following surgical revascularization. Results were compared with the data of 10 healthy volunteers. RESULTS: Preoperatively, patients showed reduced stroke volume and ejection fraction compared with volunteers (p < 0.01). Enddiastolic wall thickness (EDWT) and systolic wall thickening (SWT) were significantly lower in the patients (p < 0.01). Based on preoperative levocardiography ROI-defined myocardial segments showed a significantly lower preoperative EDWT in areas with wall motion abnormalities (7.4 +/- 2.5 mm; p < 0.01) than in normal myocardium (9.2 +/- 2.1 mm). Ejection fraction (p < 0.05), endsystolic wall thickness, and SWT (p < 0.01) improved significantly after bypass surgery. On ROI-defined analysis myocardial segments with impaired preoperative wall motion (n = 243) showed a significant increase of EDWT, ESWT and SWT (p < 0.01). CONCLUSION: In patients with CAD, cardiac MRI enables the non-invasive determination of postinfarctional LV remodeling with an increased EDWT of myocardial segments with normal regional wall motion and of the improvement in global and regional myocardial function following coronary bypass surgery.

Aged↗
PubMed2001

Lovastatin blocks basic fibroblast growth factor-induced mitogen-activated protein kinase signaling in coronary smooth muscle cells via phosphatase inhibition.

We have recently reported that the activation of mitogen-activated protein kinase (MAPK) through specific protein kinase C (PKC) isoforms is required for basic fibroblast growth factor (bFGF)-induced proliferation of coronary smooth muscle cells (cSMC). In this study, we investigated the effects of the 3hydroxy-3-methyl glutaryl coenzyme A (HMG CoA) reductase inhibitor lovastatin on bFGF-induced signal transduction in cSMC. The present study shows that lovastatin inhibits bFGF-stimulated DNA synthesis in cSMC, and that this inhibition is reversed by mevalonate (50 micromol/l) and by geranylgeranyl-pyrophosphate (1-5 micromol/l). Although lovastatin prevented Ras farnesylation the amount of bFGF-stimulated MAPK phosphorylation decreased only partially after lovastatin treatment. In addition, lovastatin pretreatment resulted in a sustained phosphorylation of MAPK. We observed a dose-dependent lovastatin-dependent increase in PKC activity, which could be prevented by mevalonate. This increase was comparable to the one induced by calyculin A (2 nmol/l), an inhibitor of protein phosphatase PP-1 and PP-2A. Lovastatin inhibited the expression of the PP-1 protein, which is involved in bFGF-induced DNA synthesis in cSMC. Thus, our data suggest that, lovastatin possibly affects the dephosphorylation processes of PKC and MAPK by inhibition of PP-1/PP-2A protein phosphatases which are involved in the bFGF-induced mitogenesis in cSMC.

Animals↗
PubMed2001

Effects of thoracic epidural anesthesia with and without autonomic nervous system blockade on cardiac monophasic action potentials and effective refractoriness in awake dogs.

BACKGROUND: The effects of thoracic epidural anesthesia (TEA) on myocardial repolarization and arrhythmogenicity are only incompletely understood. This is primarily because of the lack of appropriate experimental models. In most of the studies performed thus far, TEA was used in anesthetized animals. Baseline anesthesia itself may have modified the effects of TEA. This study investigates right atrial and ventricular repolarization by recording monophasic action potentials after TEA in awake dogs. The authors hypothesized that an antiarrhythmic role of TEA exists, which may be related to a direct effect of TEA on myocardial repolarization. METHODS: The hypothesis was tested in an in vivo canine model, in which atrial and ventricular myocardial action potential duration and refractoriness are recorded by means of monophasic action potential catheters. RESULTS: Thoracic epidural anesthesia significantly increased ventricular monophasic action potential duration for cycle lengths shorter than 350 ms. Changes in monophasic action potential duration were paralleled by a concomitant prolongation of effective refractory period (ERP) at higher rates so that the ratio of ERP to action potential duration was unaffected. CONCLUSIONS: This model helps to study the role of TEA on ventricular repolarization and arrhythmogenicity. Because lengthening of repolarization and prolongation of refractoriness may, in some circumstances, be antiarrhythmic, TEA may be protective against generation of ventricular arrhythmias mediated, e.g., by increased sympathetic tone. The results also imply that the beneficial role of TEA might be stronger at the ventricular site as compared with the atrium. At atrial sites there was only a trend toward prolongation of repolarization even at short cycle lengths.

Action Potentials↗
PubMed2001

Long-term outcome after percutaneous transluminal coronary angioplasty in patients with chronic renal failure with and without diabetic nephropathy.

OBJECTIVE: Percutaneous transluminal coronary angioplasty (PTCA) in patients on maintenance hemodialysis leads to high rates of restenosis and postinterventional complications. The additional influence of diabetes mellitus on the results of PTCA in patients with diabetic nephropathy and reduced but sufficient renal function has not been investigated before. METHODS: In a retrospective case-control study, 51 patients with reduced renal function were compared to 71 matched controls. Patients with elevated creatinine values were divided in two subgroups: diabetic nephropathy (diabetes, n = 15) and stable renal insufficiency (renal failure, n = 36). RESULTS: The control group had normal renal function (creatinine: 1.0 +/- 0.01) and a mean survival time of 3.6 +/- 0.8 years. Patients with renal failure showed a mean survival time of 2.7 +/- 0.3 years (p < 0.001), creatinine values of 2.0 +/- 0.2 and elevated fibrinogen values of 401 +/- 28 (p < 0.01). Patients with diabetes (creatinine: 2.2 +/- 0.2) had a significantly higher mortality rate with a reduced mean survival time of 1.25 +/- 0.3 years (p < 0.001), postinterventional acute renal failure (n = 2, p < 0.01) and Re-PTCA (n = 2, p < 0.05). DISCUSSION: Patients with reduced but stable renal function showed a higher mortality than comparable patients from the control group. The group of patients with diabetic nephropathy has a poor prognosis after PTCA even though renal function was only moderately reduced.

Aged↗
PubMed2001

Absence of circulating microemboli in patients with atrial fibrillation undergoing electric cardioversion.

Electrical cardioversion (CV) of atrial fibrillation (AF) is associated with an increased risk of stroke, and its appropriate prevention is still a matter of debate. It is known that, besides dislodgement of pre-existing intra-atrial thrombi, the "stunned" atrium after CV is an important cause of thrombus formation and subsequent embolism. We investigated whether CV of AF is associated with occurrence of circulating microemboli (ME) representing a sensitive marker of the actual thromboembolic activity. Twenty-nine patients (22 men) aged 54 +/- 13 years suffering from valvular (n = 5) or nonvalvular (n = 24) AF were studied. All but 1 patient (with recent-onset AF) had been put on oral anticoagulation (INR >2.0) for at least 3 weeks before and 4 weeks after successful CV. In all patients, exclusion of internal carotid artery stenosis and atrial thrombus was performed prior to CV. Five unilateral 1-hour transcranial Doppler ME monitorings over the middle cerebral artery were performed (1) before CV, and (2) immediately, (3) 4-6 h, (4) 24 h, and (5) 2-4 weeks after CV. Total absence of circulating ME was found before CV as well as during a cumulative monitoring time of 115 h after successful CV. Electrical CV of AF after at least 3 weeks of effective anticoagulation is not associated with occurrence of cerebral circulating ME. This finding requires further investigation including high-risk patients with AF undergoing CV based on different treatment protocols.

Aged↗
PubMed2000

[Incidental findings in cardiology. Diagnosing today what can cause illness tomorrow].

Among the anatomical and functional findings in cardiology, congenitally corrected transposition of the major vessels (ventricular inversion), bicuspid aortic valve and prolapse of the mitral valve with simultaneous mitral insufficiency have at least a potential for causing future problems. In such cases, regular cardiological checks or a further diagnostic work-up is to be recommended. The assessment of cardiac sounds can usually be correctly interpreted on the basis of the history, physical examination and auscultation. Among the electrocardiological findings, complete left bundle-branch block and prolongation of the QT segment, mandate clarification of a structural heart condition. Furthermore, in the event of ventricular extrasystoles, right-ventricular cardiomyopathy needs to be excluded. Such isolated conduction disorders as left-anterior fascicular block or right bundle-branch block are of no prognostic significance.

Heart Diseases↗
PubMed2000

Abnormalities of cardiac sympathetic innervation in arrhythmogenic right ventricular cardiomyopathy : quantitative assessment of presynaptic norepinephrine reuptake and postsynaptic beta-adrenergic receptor density with positron emission tomography.

BACKGROUND: The frequent provocation of ventricular tachycardia by stress or catecholamines and the efficacy of antiarrhythmic drugs with antiadrenergic properties suggest an involvement of the cardiac adrenergic system in arrhythmogenesis in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC). Previous studies demonstrated abnormalities of the presynaptic uptake-1 assessed by (123)I-MIBG-single-photon emission computed tomography. METHODS AND RESULTS: This study investigated neuronal reuptake of norepinephrine (uptake-1) and beta-adrenergic receptor density in 8 patients with ARVC and 29 age-matched control subjects. All subjects underwent positron emission tomography with the volume of distribution (V(d)) of [(11)C]hydroxyephedrine ((11)C-HED) used to assess presynaptic norepinephrine reuptake, the maximum binding capacity (B(max)) of [(11)C]CGP-12177 ((11)C-CGP-12177) to assess postsynaptic beta-adrenergic receptor density, and [(15)O]H(2)O for quantification of myocardial blood flow. Patients with ARVC demonstrated a highly significant global reduction in postsynaptic beta-adrenergic receptor density compared with that in control subjects (B(max) of (11)C-CGP-12177: 5.9+/-1.3 vs 10.2+/-2.9 pmol/g tissue, P<0.0007), whereas the presynaptic uptake-1 tended toward reduction only (V(d) of (11)C-HED: 59.1+/-25.2 vs 71.0+/-18.8 mL/g tissue, NS). There were no differences in myocardial blood flow between the groups, and plasma norepinephrine was within normal limits in patients and control subjects. CONCLUSIONS: The findings demonstrate a significant reduction of myocardial beta-adrenergic receptor density in patients with ARVC. This may result from a secondary downregulation after increased local synaptic norepinephrine levels caused by increased firing rates of the efferent neurons or as the result of impaired presynaptic catecholamine reuptake. These findings give new insights into the pathophysiology of arrhythmogenesis in ARVC, with potential impact on diagnostic evaluation and therapeutic management.

Adult↗
PubMed2000

Antidromic atrioventricular reentrant tachycardia mimicking ventricular tachycardia in the setting of previous myocardial infarction.

The differentiation between ventricular tachycardia and broad-complex supraventricular tachycardia can be extremely difficult, particularly in emergency situations. We report a case of hemodynamically compromising broad-complex tachycardia in a 63-year-old man. The patient had previously sustained an anteroseptal myocardial infarction and had subsequently undergone coronary artery bypass surgery because of triple-vessel coronary artery disease. Intravenous treatment with ajmalin terminated the tachycardia and revealed preexcited QRS complexes compatible with the presence of a left-sided atrioventricular accessory pathway. An antidromic atrioventricular reentrant tachycardia (identical to the clinical tachycardia) was induced during an electrophysiologic study. In conclusion, there are several causes of broad-complex tachycardia, even in patients with previous myocardial infarction, and, where doubt exists, electrophysiologic studies should be performed.

Coronary Artery Bypass↗