[Syncope of uncertain cause and sudden cardiac death in young patients].
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Adolescent↗
Biomedical subjects
C Wolpert
Publications and source records attributed to C Wolpert.
[Amiodarone or ICD in patients with cardiac insufficiency. SCD-HeFT Study].
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Amiodarone↗
[Primary electrical heart disease in adulthood--electrophysiological findings and therapy].
Sudden cardiac death accounts for 100,000 victims in Germany per year. Predominantly, patients with structural heart disease such as coronary artery disease or dilated cardiomyopathy are affected. However, approximately 5-10% of sudden deaths hit patients without structural disease of the heart. The proportion of young patients (< 40 years of age) in this group is even higher (10-20%). In younger patients significantly more diseases like hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia and primary electrical diseases of the heart could be observed such as long QT syndrome, short QT syndrome, Brugada syndrome and catecholaminergic polymorphic ventricular tachycardia. The primary electrical diseases are different concerning their electrocardiographical pattern, clinical triggers of arrhythmias, results of invasive diagnostics and therapy. Meanwhile, molecular genetic screening can reveal specific mutations of ion channels and can identify consecutive functional defects. The significance of programmed ventricular stimulation is at present unclear concerning risk stratification in patients with Brugada syndrome and short QT syndrome and of no significance in long QT syndrome and catecholaminergic polymorphic ventricular tachycardias. The implantable cardioverter defibrillator is the therapy of choice in most symptomatic patients. With increasing knowledge as a result of sophisticated molecular genetic screening, identification of underlying ion channel defects and new details of the mechanisms of arrhythmogenesis, a potential genotype-guided therapy will gain more importance in the future.
Adult↗
Incidence and electrophysiological characteristics of spontaneous ventricular tachyarrhythmias in high risk coronary patients and prophylactic implantation of a defibrillator.
OBJECTIVES: To assess the incidence and electrophysiological characteristics of spontaneous ventricular tachyarrhythmias after implantable cardioverter-defibrillator (ICD) implantation for primary prevention. DESIGN: Prospective observational study. PATIENTS: 41 consecutive patients, who fulfilled MADIT (multicenter automatic defibrillator implantation trial) I criteria, except for suppressibility by procainamide, and who received a prophylactic ICD. INTERVENTIONS: Subpectoral implantation of an ICD. MAIN OUTCOME MEASURES: Incidence of ventricular tachyarrhythmias and their electrophysiological characteristics with respect to timing of the arrhythmia, tachyarrhythmia cycle length, mode of termination, and clinical relevance. RESULTS: During a mean (SD) follow up of 30 (21) months 18 of 41 (43.9%) patients experienced 142 appropriate ICD treatments. The mean (SD) time to first event was 9.6 (15.1) months. One patient had ventricular fibrillation (VF), 12 patients ventricular tachycardia (VT), and five both VT and VF. The mean (SD) cycle length of monomorphic VT was 306 (42) ms. Of 142 episodes, 117 (82.3%) were terminated by antitachycardia pacing and another 25 (17.6%) by ICD discharges. Cumulative survival of hypothetical death, defined as treated VT with a cycle length < 260 ms or VF, was 83.2% after one year and 78.4% after two years. CONCLUSIONS: Patients with a left ventricular ejection fraction < 35%, a history of myocardial infarction, non-sustained VT, and inducible VT/VF are at high risk of VT/VF early after implantation. Therefore, implantation of a tiered treatment defibrillator seems to be justified.
Aged↗
The patient's informed consent for pacemakers and ICD implantation: how to write and how to explain it.
Written informed consent for pacemaker and ICD patients should be easy to understand and provided in written form in the patient's language. Comprehensiveness is required. It is essential to address driving and running machines, complication rates, benefits in appropriate hierarchical order and future necessary interventions. Eventually potential risks, e.g., flying, sports, sexual activity should be mentioned. It is important to explain pacemaker systems and ICD devices in details including cardiac resynchronization therapy (CRT) for heart failure. One of the main aspects concerns protection of human subjects participating in clinical studies. Informed consent necessitates a statement that the study involves research. This statement should include explanation of the purposes of the study, expected duration, description of the procedures, identification of experimental procedures, description of foreseeable risks or discomforts, and disclosure of alternative procedures. Further information should be given on psychological concerns, sexual activity, driving and quality of life in pacemaker and ICD patients.
Adult↗
Potential device interaction of a dual chamber implantable cardioverter defibrillator in a patient with continuous spinal cord stimulation.
Spinal cord or thalamic deep brain stimulation with a pacemaker is becoming more important in the treatment of drug refractory pain due to peripheral vascular disease, angina pectoris and intractable tremor in patients with neurologic disorders such as Parkinson's disease. An additional indication for a cardiac pacemaker or implantable cardioverter defibrillator raises concerns about possible interactions between the implanted electrical devices. We report on a patient with existing spinal cord stimulation who survived sudden cardiac death and received a dual chamber cardioverter defibrillator capable of delivering tiered therapies in both the atrium and ventricle.
Aged↗
[Cardiac resynchronization therapy by biventricular pacing. How many patients with left ventricular dysfunction are eligible?].
BACKGROUND AND OBJECTIVE: Cardiac resynchronization therapy by multisite biventricular pacing presents an additive therapeutic option in the treatment of severe congestive heart failure. The objective of the study was to evaluate how many patients with left ventricular dysfunction may potentially benefit from this therapy. METHODS: A total of 975 patients were screened for the prevalence of left ventricular dysfunction. Patients with a left ventricular ejection fraction (LVEF) <45 % were included into the investigation. Potential benefit of biventricular pacing was presumed in the presence of: LVEF < 35 %, severe heart failure (NHYA class III or IV), intrinsic left bundle branch block pattern with QRS interval > 150 ms and the absence of atrial fibrillation in the last 3 months before study inclusion. RESULTS: In 203 patients (168 male, 35 female, mean age: 64 +/- 11) an LVEF <45 % was found. A total of 12 of these patients (6 %) or 12 of 113 patients (11 %) with an LVEF <35 % were identified as appropiate candidates for biventricular resynchronization therapy. CONCLUSIONS: Cardiac biventricular pacing currently serves as a therapeutic option for a relatively small subgroup of patients with left ventricular dysfunction. Focusing on estimations that the incidence of heart failure in Germany amounts to more than 100.000 cases per year our results suggest that after all more than 6.000 patients per year may potentially benefit from electric resynchronization therapy. This number may increase substantially if prospective studies can prove that patients with heart failure and atrial fibrillation or left ventricular conduction delay due to univentricular pacing also benefit from cardiac resynchronization therapy.
Aged↗
[Expansion of the Multilink-Tristar stent after direct implantation and predilatation: comparison of clinical, angiography and intravascular ultrasound parameters].
Coronary stenting has become the primary therapeutic option for many coronary lesions. As opposed to conventional stenting the advantages of direct stenting are a reduction of procedural time, radiation exposure and costs. However, data about the incidence of in-stent restenosis are so far not available. It was the aim of this prospective study to compare the expansion of the Multilink stent after direct stenting and predilatation by quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS). Between January 2000 and June 2001, 82 patients were assigned to direct stenting (46 lesions) or predilatation (40 lesions) in lesions of coronary arteries > 3 mm. The procedural success rate was 92% in patients undergoing direct stenting. The baseline clinical characteristics were similar in both groups. The comparison of the angiographic data shows that direct stenting was performed in lesions with a lower degree of stenosis (71 +/- 12% vs 79 +/- 11%, p = 0.01) and that significantly shorter stents were used (14.4 +/- 3.0 vs 17.8 +/- 4.1 mm, p = 0.0007). The mean stenosis length was not significantly different in either group (10.5 +/- 3.4 vs 11.7 +/- 4.3 mm, n.s.). The QCA data after stent implantation show no differences of either implantation technique. Stent expansion was assessed by IVUS estimation of the proximal, distal and minimal in stent area. The minimal in-stent area (9.53 +/- 3.23, mm2 vs 8.65 +/- 1.96 mm2, n.s.) and the stent symmetry index (0.88 vs 0.88 n.s.) were not different in either patient group. These results indicate that in this subset of selected coronary lesions > 3 mm, elective stent implantation with and without predilatation effectively can achieve comparable stent expansion as assessed by QCA and IVUS. In comparison to conventional stent implantation stents, which were implanted without predilatation, were significantly shorter to cover the same lesion length.
Adult↗
[Cardiac imaging and electrophysiology--what do new 3-dimensional mapping methods contribute?].
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Catheter Ablation↗
Efficacy of pacing therapies for treating atrial tachyarrhythmias in patients with ventricular arrhythmias receiving a dual-chamber implantable cardioverter defibrillator.
BACKGROUND: Although overdrive pacing for treating atrial flutter is well established, the efficacy of device-based atrial pacing for treating spontaneous atrial tachyarrhythmias in patients with implantable cardioverter defibrillators (ICD) is unknown. This study evaluated the efficacy of novel pacing therapies for treating atrial tachyarrhythmias in patients receiving a dual-chamber ICD to treat ventricular tachyarrhythmias. METHODS AND RESULTS: A Jewel AF ICD was implanted in 537 patients with ventricular arrhythmia who were followed for 11.4+/-8.2 months (74% had a documented history of atrial tachyarrhythmias). The device discriminated atrial tachycardia (AT) from atrial fibrillation (AF) on the basis of cycle length and regularity, and it used 3 different methods of overdrive atrial pacing (Ramp, Burst+, and 50-Hz burst) to treat AT episodes and one method (50-Hz burst) to treat AF episodes. Pacing successfully terminated 59% of 1500 spontaneous AT episodes in 127 patients and 30% of 880 AF episodes in 101 patients (P<0.001). With AT and AF episodes combined, pacing efficacy was 48%. Pacing efficacy was significantly reduced at AT cycle lengths </=220 ms and AF cycle lengths </=160 ms (P<0.01) The median time from pacing to AT/AF termination was 1.1 minute for the pacing successes and 96 minutes for the failures (P<0.001). CONCLUSIONS: Atrial pacing terminated 48% of AT/AF episodes in patients with a history of ventricular arrhythmias. Pacing efficacy was greater for device-classified AT than AF. Pacing efficacy was significantly influenced by tachycardia cycle length. Successful pacing significantly reduces the time required for AT/AF termination.
Aged↗
[A new dual-chamber defibrillation system: duration, frequency and circadian variation of recurrent supraventricular tachyarrhythmias].
BACKGROUND: The treatment of concomitant atrial tachyarrhythmias in patients with malignant ventricular tachyarrhythmias is a major challenge for new defibrillator devices. Atrial fibrillation is not only responsible for inappropriate ventricular therapies, but also reduced left ventricular performance, especially in patients with heart failure and severely depressed left ventricular function. Furthermore, it is a strong risk factor for the development of thromboembolism. NEW SYSTEM: A new dual-chamber implantable defibrillator is capable of tiered atrial therapies for both regular and irregular atrial tachyarrhythmias. In first investigations a high sensitivity and specificity could be shown as well as a promising therapy efficacy of atrial antitachycardia ramp and burst pacing for the treatment of atrial tachycardias. Atrial ramp pacing has shown to be successful for regular atrial tachyarrhythmias in up to 60 to 70% of all episodes. The results have supported a programming of a high first shock energy for treatment of atrial fibrillation. The incidence of atrial fibrillation in patients with a history of atrial fibrillation or without is much higher in the present investigated patient populations than expected. CONCLUSION: The more complicated and subtle new dual-chamber detection algorithm has proven to be safe and effective both for the detection of ventricular tachycardia but also in terms of an increase of specificity and a reduction of inappropriate ventricular therapies for atrial tachyarrhythmias.
Atrial Fibrillation↗
[Electrophysiological characterization of connexin 40 deficient hearts--in vivo studies in mice].
Intercellular communication is not only mediated by extracellular transmitters, but also directly by gap junction channels. One channel is composed of two hexameric hemichannels which consist of six polypeptide subunits called connexines (Cx). In the mammalian heart the following connexines have been documented: Cx37, Cx40, Cx43, Cx45, Cx46, Cx50 and Cx57. The labeling by number represents the rounded, molecular mass of the amino acid sequences given in kD. If identical connexin-isotypes form both connexons of a gap junction channel, homotypic coupling exists and a homomeric gap junction channel is formed. Different connexin-isotypes within both connexons cause form heterotypic coupling and heteromeric gap junction channels. Each channel type has specific properties regarding permeability and electrical conductance. Beside a typical age-dependent alignment of gap junction channels on the surface of the cardiac myocytes, regional distribution of the different connexins is different at distinct parts of the mouse heart. Cx40 is not found in the ventricular working myocardium of mice. In the atria as well as in the conduction system, Cx40 is the most frequently expressed. In line with the localization and the conduction properties of distinct homotypic gap junction channels, the Cx40 deficient mouse is suitable for analysis of atrial arrhythmias. Cx40-deficiency in the mouse heart results in characteristic ECG changes like first degree atrioventricular block and prolongation of the QRS duration. Thus, an impairment of the sinuatrial, intraatrial and atrioventricular conduction properties is documented in Cx40 deficient mice. These observations are associated with an increased atrial vulnerability. The Cx40 deficient mouse provides a good example of the relevance of transgenic mouse models to clarify the mechanisms of arrhythmogenesis. The clinical impact of future transgenic mouse models depends on the cooperation of geneticists, basic researchers and clinicians.
Animals↗
Algorithms for better arrhythmia discrimination in implantable cardioverter defibrillators.
The discrimination of concomitant atrial tachyarrhythmias and sinus tachycardias in patients with malignant ventricular tachyarrhythmias is a major challenge for new defibrillator devices. Different algorithms have now been established to distinguish between atrial and ventricular tachyarrhythmias. Furthermore, new dual-chamber implantable defibrillators are capable of tiered atrial therapies for both regular and irregular atrial and ventricular tachyarrhythmias. The increasingly complex and subtle dual-chamber detection algorithms have proven to be safe and effective for the detection of ventricular tachycardia, and also in terms of an increase in specificity and a reduction in inappropriate ventricular therapies for supraventricular tachyarrhythmias. Stable electrode position, and a continuous and correct atrial signal quality, are prerequisites for atrial therapies and algorithms for arrhythmia discrimination.
Algorithms↗
Prevalence of left atrial chamber and appendage thrombi in patients with atrial flutter and its clinical significance.
OBJECTIVES: The study was done to assess the prevalence of left atrial (LA) chamber and appendage thrombi in patients with atrial flutter (AFl) scheduled for electrophysiologic study (EPS), to evaluate the prevalence of thromboembolic complications after transesophageal echocardiographic (TEE)-guided restoration of sinus rhythm and to evaluate clinical risk factors for a thrombogenic milieu. BACKGROUND: Recent studies showed controversial results on the prevalence of atrial thrombi and the risk of thromboembolism after restoring sinus rhythm in patients with AFl. METHODS: Between 1995 and 1999, patients with AFl who were scheduled for EPS were included in the study. After transesophageal assessment of the left atrial appendage and exclusion of thrombi, an effective anticoagulation was initiated and patients underwent EPS within 24 h. RESULTS: We performed 202 EPSs (radiofrequency catheter ablation, n = 122; overdrive stimulation, n = 64; electrical cardioversion, n = 16) in 139 consecutive patients with AFl. Fifteen patients with a thrombogenic milieu were identified. All of them had paroxysmal atrial fibrillation (AF). Transesophageal echocardiography revealed LA thrombi in two cases (1%). After EPS no thromboembolic complications were observed. Diabetes mellitus, arterial hypertension and a decreased left ventricular ejection fraction were found to be independent risk factors associated with a thrombogenic milieu. CONCLUSIONS: The findings of a low prevalence of LA appendage thrombi (1%) in patients with AFl and a close correlation between a history of previous embolism and paroxysmal AF support the current guidelines that patients with pure AFl do not require anticoagulation therapy, whereas patients with AFl and paroxysmal AF should receive anticoagulation therapy. In addition, the presence of clinical risk factors should alert the physician to an increased likelihood for a thrombogenic milieu.
Aged↗
Case report: regional cerebral hypoperfusion induced by ventricular tachycardia - short-term hippocampal hypoperfusion and its potential relationship to selective neuronal damage.
BACKGROUND: Focussing on regional cerebral hypoperfusion during hemodynamically stable, but borderline hypotensive, sustained ventricular tachycardia (VT) experimental studies show (1) a reduction of cerebral blood flow (CBF) during tachyarrhythmias in contrast to the concept of CBF autoregulation, (2) a mediation of hypoperfusion by neuronal and humoral mechanisms, and (3) an involvment of microcirculation due to an ischemic stress response of the cerebral tissue. The clinical relevance of these observations remains still unclear. CASE REPORTS: Two patients with coronary artery disease, left ventricular dysfunction and sustained monomorphic VT underwent electrophysiological study. VT was induced and the tracer (99m)Tc-HMPAO was injected after 3 minutes of ongoing VT. Regional CBF during this life threatening arrhythmia was determined with brain SPECT. A scanning protocol was performed after termination of VT. The measurements were repeated at baseline during normofrequent sinus rhythm (SR) one week later. CBF during SR was significantly reduced in the temporal lobe in comparison to the conditions during stable VT, particularly in the left hippocampus. CONCLUSION: The reduction of hippocampal CBF due to cerebrovascular vasoconstriction and neuronal reflex mechanism previously observed in experiments during stable, sustained VT can be confirmed in a clinical scenario by high resolution (99m)Tc-HMPAO brain SPECT. This supports the hypothesis that repetitive stable VT can play a role in the pathophysiology of cerebrovascular insufficiency. Further clinical studies are needed to analyze the impact of tachyarrhythmias on cognitive and mnemic function.
Aged↗
Unique and shared functions of different connexins in mice.
BACKGROUND: Connexins are the protein subunits of intercellular gap junction channels. In mammals, they are encoded by a family of at least 15 genes, which show cell-type-specific but overlapping patterns of expression. Mice lacking connexin43 (Cx43) die postnatally from obstruction of the right ventricular outflow tract of the heart. To discriminate between the unique and shared functions of Cx43, Cx40 and Cx32, we generated two 'knock-in' mouse lines, Cx43KI32 and Cx43KI40, in which the coding region of the Cx43 gene was replaced, respectively, by the coding regions of Cx32 or Cx40. RESULTS: Heterozygous mutants were fertile and co-expressed the wild-type and the corresponding recombinant allele in all tissues analyzed. Heterozygous Cx43KI32, but not Cx43KI40, mutant mothers were unable to nourish their pups to weaning age, possibly reflecting a defect in milk ejection. Homozygous mutant males were sterile because of extensive germ-cell deficiency. The ovaries of homozygous Cx43KI32 neonates exhibited all stages of follicular development and ovulation. The hearts of homozygous Cx43KI32 neonates showed mild morphological defects, but the cardiac morphology of homozygous Cx43KI40 neonates was relatively normal. Spontaneous ventricular arrhythmias were observed in most Cx43KI40 and some Cx43KI32 mutant mice, suggesting increased ventricular vulnerability in these mice. CONCLUSIONS: The postnatal lethality of Cx43-deficient mice was rescued in Cx43KI32 or Cx43KI40 mice, indicating that Cx43, Cx40 and Cx32 share at least some vital functions. On the other hand, Cx43KI32 and Cx43KI40 mice differed functionally and morphologically from each other and from wild-type mice. Thus, these connexins also have unique functions.
Animals↗
Autistic symptoms among children and young adults with isodicentric chromosome 15.
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Adolescent↗
[A new ICD morphology criterion for differentiating supraventricular and ventricular tachycardia].
The high incidence of inappropriate therapies due to supraventricular tachycardia remains a major unsolved problem of the implantable cardioverter defibrillator. A new morphology discrimination (MD) algorithm has been introduced to improve specificity of ICD therapy without loss of sensitivity. It was the aim of this study to systematically analyze sensitivity and specificity of the MD criterion in combination with the enhanced detection criteria sudden onset and rate stability in the detection of ventricular and supraventricular tachycardia. After ICD implantation in 259 patients, 787 detected episodes in 74 patients with available stored electrograms were documented during a follow-up period of 359 +/- 214 days. With a nominal programming of the MD algorithm at > or = 60%, sensitivity and specificity for all episodes were 82.6%/77.2%. For sinus tachycardia, atrial fibrillation and atrial flutter the specificities were 80.6%, 69.6% and 75%, respectively. In patients with primarily appropriate MD detection, sensitivity and specificity significantly improved to 95.8%/91.7%. Programming the sudden onset criterion with < 100 ms and the stability criterion with < 50 ms, sensitivity and stability of the combined application of the MD algorithm and sudden onset and MD algorithm and stability were 96.2%/52.2% and 94.4%/63.8%, respectively. The MD criterion in combination with other enhanced detection criteria might significantly improve specificity of tachyarrythmia detection of ICD therapy.
Aged↗