Biomedical subjects

W Jung

Publications and source records attributed to W Jung.

At least 145 records · Page 8Linked to original sources

PubMed1996

Multicenter experience with a pectoral unipolar implantable cardioverter-defibrillator. Active Can Investigators.

OBJECTIVES: The purpose of this study was to prospectively examine in a multicenter study the methods of use, efficacy and complications of a unipolar cardioverter-defibrillator in patients at risk for sudden cardiac death. BACKGROUND: Implantation of cardioverter-defibrillators in the pectoral region offers a significant opportunity to improve the management of patients with life-threatening arrhythmias. Unipolar, single-lead, pectoral implantable cardioverter-defibrillators might decrease related mortality, morbidity and costs in the care of such patients. METHODS: From November 3, 1993 to May 8, 1995, a unipolar defibrillator (Medtronic model 7219C) was selected for use in 473 patients from 74 centers (386 [82%] men, 87 [18%] women; mean [+/- SD] age 59 +/- 13 years, range 16 to 88). The clinical indication for use was ventricular fibrillation in 157 patients, sustained ventricular tachycardia in 236, both ventricular tachycardia and ventricular fibrillation in 53 and syncope or inducible ventricular tachycardia/ventricular fibrillation in 27. Coronary artery disease was present in 323 patients (68%). The mean left ventricular ejection fraction was 0.36 +/- 0.15 (range 0.10 to 0.85). The distribution of New York Heart Association congestive heart failure was class I = 34%; class II = 45%; class III = 17%; and class IV = 2%. RESULTS: The unipolar cardioverter-defibrillator was inserted successfully in 464 (98%) of 473 candidates. Effective defibrillation occurred with the first shock polarity tested in 88% of patients, after a polarity switch in 8% and after lead or generator repositioning in 2%. The stored energy defibrillation threshold was obtained at implantation in 339 patients (72%) and was 11.5 +/- 6.1 J, with 72% of patients having a defibrillation threshold < or = 12 J. The mean "skin-to-skin" implantation time was 96 +/- 45 min (range 25 to 335 min). Complications occurred in 29 patients (6%). Device therapy for 2,160 spontaneous ventricular tachycardia or fibrillation episodes occurred in 128 patients (27%) over a 2,732 device-month experience (range 0 to 17.2) and was effective in 98.7% of episodes. There were 14 deaths (10 nonsudden cardiac, 3 sudden cardiac, 1 noncardiac). Cumulative survival, on an intention-to-treat basis from all causes of death at 17.2 months, was 94.4%. CONCLUSIONS: Unipolar pectoral implantable cardioverter-defibrillators can be inserted with a high likelihood of success in a relatively brief procedure. Defibrillation thresholds are low, morbidity is modest, and survival rates are good with this new type of implantable cardioverter-defibrillator.

Cardiac Pacing, Artificial↗

PubMed1996

[Driving restrictions for arrhythmia patients--with special reference to the implantable cardioverter/defibrillator].

UNLABELLED: The series "Illness and Vehicular Traffic", published by the German Federal Ministry for Transportation, has set forth the following guidelines on the subject of driving for patients with cardiac rhythm disorders: "Anyone suffering from disorders of cardiac rhythm which might, on occasion, lead to the repeated interruption of oxygen supply to the brain and thus cause disturbances in consciousness or even loss of consciousness, must be considered unsuitable for driving a motor vehicle of any class." While these guidelines are essentially indisputable, it remains unclear how they affect patients with an implantable cardioverter/defibrillator (ICD). The issue is further complicated by the fact that these patients, as a rule, suffer from malignant and life-threatening cardiac rhythm disorders, often owing to a severe cardiac disorder (primarily coronary heart disease and cardiomyopathy). It was the purpose of a recent study to investigate how medical permission to drive in ICD patients is handled in various European countries. A specifically designed questionnaire was addressed to 46 European National Delegates of the Working Groups on Cardiac Pacing in order to determine their present practices and criteria utilized when advising driving restrictions to patients (pts) after ICD implantation. RESULTS: Of the 39 (83%) respondents, 22 (56%) cardiologists advised all pts to abstain from driving. Permanent driving abstinence was advised by 13 (33%) of the responding cardiologists, while temporary driving abstinence for periods of 3 to 18 months (mean 9 +/- 4 months) was recommended by 26 (67%) physicians. Criteria for subsequently advising a longer period of driving abstinence were: presyncope by 15 (38%), syncope by 13 (33%) and multiple shocks by 2 (5%) cardiologists. Despite medical advice not to drive, about one-third of pts resume driving. About half of the pts resumed driving after 6 months, with the vast majority driving 12 months after ICD implantation. Two pts experienced ICD discharges while driving, but no motor vehicle accident occurred. One patient had a motor vehicle collision with a fatal outcome which was not caused by loss of consciousness or ICD discharge. CONCLUSIONS: 1) Fatal accidents of ICD discharges while driving are a rare finding in ICD pts. 2) About half of the physicians always advise their pts to cease driving for a period of 9 +/- 4 months. Despite this medical advice pts resume driving 6 months after ICD implantation. 3) Criteria used in advising driving abstinence are not uniform among physicians. In symptomatic bradyarrhythmias the driving privilege may be reinstated after pacemaker implantation provided that symptoms resulting from the interruption of the oxygen supply to the brain have not recurred.

Accidents, Traffic↗

PubMed1996

[Exogenous adenosine as an anti-arrhythmia agent].

Adenosine has potent cardiac electrophysiologic effects including a negative chronotropic action on the sinus node and a predominant negative dromotropic action on the AV node. The latter property has mainly led to the use of adenosine as antiarrhythmic agent for the acute management of paroxysmal supraventricular tachycardia (PSVT) mediated by a reentrant mechanism involving the AV node. The effects of adenosine are dose-dependent and of very short duration since the half-life is less than 10s. The efficacy rates for termination of AV reentrant tachycardias were found to be 35% with 3 mg, 60-70% with 6 mg, 80% with 9 mg, and 90-95% with 12 mg adenosine. The AV nodal depressant effects of adenosine have also been used for determining the mechanism of wide QRS tachycardias for differentiating supraventricular tachyarrhythmias with aberrant conduction from ventricular tachycardia. Adenosine either terminates or slows almost all types of supraventricular tachyarrhythmias or it leads to unmasking of the underlying mechanism such as atrial flutter with aberrant conduction. One form of ventricular tachycardia, the idiopathic type originating from the right ventricular outflow tract can usually be terminated with adenosine due to its cAMP-mediated mechanism. Adenosine is helpful to detect or to increase preexcitation which is important for planning a catheter ablation procedure since the preexcitation pattern allows to localize the accessory pathway. Since the action of adenosine usually does not alter the accessory pathway conduction it is also useful for control ablation efficacy noninvasively in terms of antegrade conduction and during ventricular pacing for the retrograde conduction. Further evaluation and research is necessary for better understanding of adenosine action on the human atrial electrophysiology since it provokes atrial fibrillation in some patients, and of adenosine action on the different pathways in AV nodal reentrant tachycardias and some accessory pathways with decremental (AV nodal-like) conduction properties.

Adenosine↗

PubMed1996

[Intra-atrial defibrillation--limits and possibilities].

UNLABELLED: External cardioversion has been a remarkably effective and safe method for termination of atrial fibrillation. Originally introduced by Lown and coworkers in 1962, it has been an accepted mode of acute therapy. The disadvantages of this approach are the need for general anaesthesia and the demand for high energies up to 360 J. Intraatrial defibrillation of atrial fibrillation using low energy shocks has been intermittently investigated as an alternative to the external method for over two decades. The following aspects have to be considered during the use of intraatrial defibrillation: the efficacy of this method, the safety, i.e. the potential risk of inducing a proarrhythmic, the patient acceptance during recurrent shock discharges, the phenomenon of the atrial stunning, the risk of a thromboembolism, and the necessity of anticoagulation. Our own experience of 25 patients and the data in the literature indicate that internal atrial defibrillation is a safe and effective method for termination of atrial fibrillation, and is particularly useful in patients who have been refractory to external cardioversion. The mean atrial defibrillation threshold for termination of chronic atrial fibrillation was 9.1 +/- 7.4 J in our patient population, corresponding with a leading edge voltage of 376 +/- 175 V and an impedance of 53 +/- 8 omega. At an energy level of 300 V, 40% of the patients could be effectively converted into sinus rhythm. Apart from the induction of three ventricular depolarizations no other proarrhythmic events could be observed during the delivery of approximately 200 shock discharges, in particular no sustained ventricular tachyarrhythmias. The mean pain score at 60 V was 3.0 +/- 1.1 corresponding with a mild discomfort, and at 140 V 4.6 +/- 0.7 corresponding with a moderate to severe discomfort. Serial multiplane transesophageal echocardiographic examinations demonstrated a reduction of the flow in the left atrial appendage following intraatrial defibrillation. These reduced flows in the left atrial appendage recovered within 7 days. On June 3, 1996 an atrial defibrillator was successfully implanted for the first time in Germany in a patient with symptomatic, drug refractory atrial fibrillation. CONCLUSIONS: Intraatrial defibrillation is a safe and effective method for termination of atrial fibrillation. The electrotherapy with an implantable atrial defibrillator should be considered as an alternative approach in patients with symptomatic, long lasting, and drug refractory episodes of atrial fibrillation.

Atrial Fibrillation↗

PubMed1995

Heart rate to work rate relation throughout peak exercise in normal subjects as a guideline for rate-adaptive pacemaker programming.

We investigated the physiologic heart rate (HR) to work rate (WR) relation throughout peak exercise in normal subjects as a guideline for rate-adaptive pacemaker slope programming. The study group consisted of 41 middle-aged subjects (22 men and 19 women) without evidence of cardiopulmonary disease. Peak-exercise stress tests were performed on a calibrated treadmill by using the symptom-limited "ramping incremental treadmill exercise" (RITE) protocol. The HR response, oxygen uptake, and treadmill workload increments were assessed simultaneously. The HR/WR slope, as determined using linear regression analysis, was 0.37 +/- 0.13 beats/min/W for the entire study group, which indicates an upper range increase of 5 beats/10 W increase of external treadmill work performed, using the mean value +/- 1 SD. Men generated an HR/WR slope of 0.32 +/- 0.09 beats/min/W, and women, 0.43 +/- 0.15 beats/min/W, indicating a significant sex-related difference in the HR/WR relation (p < 0.01). Thus, to achieve an appropriate matching of HR with patient effort, rate-adaptive pacemakers should generate an average increase of approximately 5 beats per increase in 10 W of external treadmill work. The HR/WR relation can easily be determined to provide the clinician with a minimal check system to avoid a hyper- or hypochronotropic paced response to exercise.

Adult↗

PubMed1995

The role of lymphocyte subsets and adhesion molecules in T cell-dependent cytotoxicity mediated by CD3 and CD28 bispecific monoclonal antibodies.

The cure of human Hodgkin's tumors heterotransplanted into SCID mice can be achieved by two bispecific monoclonal antibodies (Bi-mAb) directed against the tumor-associated CD30 antigen and CD3 and CD28, respectively, and normal peripheral human blood T cells. We investigated the role of lymphocyte subsets and adhesion molecules in this Bi-mAb-mediated cytolysis. CD4+ lymphocytes were the most rapidly expanding subpopulation, but Bi-mAb-directed cytotoxicity was mediated preferentially by CD8+ lymphocytes and effector cells belonging to the CD45RO+ "memory" pool. Blocking of the LFA-1/ICAM-1 or CD2/LFA-3 adhesion pathways by mAb decreased Bi-mAb-mediated cytotoxicity. This was not due to inhibition of aggregate formation between Bi-mAb-coated T lymphocytes and target cells. Cross-linking of LFA-1 or CD2 molecules on lymphocytes prestimulated with Bi-mAb bound to CD3 and CD28 antigen lead to a more pronounced and prolonged rise in the intracellular concentration of free Ca2+. Additional CD2 cross-linking resulted in the tyrosine phosphorylation of distinct proteins. These findings indicate that adhesion molecules play a critical role and function as co-stimulatory signals rather than as cellular contact mediators in CD3 and CD28 Bi-mAb-stimulated T lymphocytes.

Antibodies, Bispecific↗

PubMed1995

Prospective study of retrograde coronary venography in patients with posteroseptal and left-sided accessory atrioventricular pathways.

The morphologic features of the coronary vein system was prospectively studied with retrograde venography in 117 patients with left-sided (78 patients) and posteroseptal accessory pathway (39). Findings were compared with accessory pathway localization. A mean of 3.3 +/- 1.5 venous branches draining into the coronary sinus or the great cardiac vein could be visualized. The morphologic condition was described and classified. Incidence, morphologic condition, and distribution did not differ between left-sided and posteroseptal accessory pathway. Venous abnormalities including ectasy, diverticulum, narrowing, angulation, and hypoplasia occurred in 22.2%. Diverticulum and narrowing were present in posteroseptal accessory pathway only and always related to the successful ablation site. In patients with left-sided accessory pathway, ectasy, angulation, and hypoplasia were found. Anomalies were less frequent (9% vs 43.6%, p < 0.001) and had no relation to accessory pathway localization. However, the successful ablation site was in 42.3% located < 5 mm to an angiographically visualized venous branch. In conclusion, posteroseptal accessory pathways are often related to coronary sinus abnormalities. In patients with a left-sided accessory pathway venous malformation is uncommon, whereas a close anatomic relation exists between accessory pathway localization and venous ventricular branches.

Adolescent↗

PubMed1995

Randomized comparison of aspirin and phenprocoumon for prevention of right-sided thromboembolic complications associated with transvenous defibrillation leads.

Death due to pulmonary embolism caused by thrombosis formation along a pacing wire has been reported in patients with antibradycardia pacemakers. The purpose of this prospective and randomized study was to evaluate the effects of prophylactically assigned aspirin (100 mg per day) or phenprocoumon (a coumarin derivative) on the incidence of right-sided thromboembolic complications associated with transvenous defibrillation leads. Multiplane transoesophageal echocardiography and pulmonary scintigraphy were performed in 62 consecutive patients immediately and 6 +/- 2 months after transvenous defibrillator implantation. Aspirin or phenprocoumon was administered to the patients in a randomized and parallel manner. By means of multiplane transoesophageal echocardiography and pulmonary scintigraphy no thromboembolic events were observed immediately after transvenous defibrillator implantation. After 6 +/- 2 months, however, multiplane transoesophageal echocardiography disclosed thrombi on the transvenous leads in 13 of 62 patients (21%) despite antithrombotic therapy. At the same time, pulmonary scintigraphy did not reveal any defects compatible with pulmonary embolism. Although thrombi occurred in only four patients treated with phenprocoumon, but in nine patients receiving aspirin, this difference was statistically insignificant. Other variables associated with the occurrence of thrombosis formation were not identified. One fatal intracranial haemorrhage occurred in the phenprocoumon group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

The "low intensity treadmill exercise" protocol for appropriate rate adaptive programming of minute ventilation controlled pacemakers.

The objective of rate adaptive pacemakers that measure minute ventilation by transthoracic impedance is to simulate the physiological relationship of the sensed signal to the sinus node response during exercise, thus achieving an appropriate matching of heart rate with patient effort. The purpose of this study was to determine the physiological relationship between heart rate and minute ventilation (HR/VE) during peak exercise testing in order to develop a database for appropriate rate adaptive slope programming of minute ventilation controlled pacemakers. Due to several clinical limitations of peak exercise testing, it was additionally determined whether the 35-watt "low intensity treadmill exercise" (LITE) protocol can be used as a substitute for peak exercise test using the "ramping incremental treadmill exercise" (RITE) protocol in order to assess the correct HR/VE slope below the anaerobic threshold. The stress tests were performed on a treadmill with the collection of breath-by-breath gas exchange. Linear regression analysis was used to determine the HR/VE slope below and above the anaerobic threshold and during the early, dynamic phase of low intensity exercise with the RITE and LITE protocols, respectively. The results of this testing in 41 healthy subjects demonstrated that the HR/VE relationship throughout treadmill exercise using the RITE protocol was not linear but curvilinear in nature, with a steeper HR/VE slope of 1.54 +/- 0.51 below versus 1.15 +/- 0.37 above the anaerobic threshold (P < 0.005). The HR/VE slope determined during the early, dynamic phase of the LITE protocol (1.58 +/- 0.88) did not differ from the HR/VE slope from rest to anaerobic threshold obtained using the peak exercise RITE test (1.54 +/- 0.51; P = 0.79). Rate adaptive pacing should simulate the curvilinear relationship between heart rate and minute ventilation from rest to peak exercise. The HR/VE slope determined during the early, dynamic phase of low intensity exercise represents the HR/VE slope derived from the RITE protocol below the anaerobic threshold. According to the peak exercise database, the slope above anaerobic threshold can easily be calculated as a percentage of the slope below the anaerobic threshold. The LITE protocol can, therefore, be effectively performed as a substitute for peak exercise stress tests to determine the correct pacemaker rate response factor in order to obtain a physiological heart rate to minute ventilation relationship for the appropriate matching of paced heart rate with patient effort.

Anaerobic Threshold↗

PubMed1995

Incidence of ICD lead related complications during long-term follow-up: comparison of epicardial and endocardial electrode systems.

UNLABELLED: The aim of this study was to evaluate the long-term stability of epicardial and endocardial lead systems for third-generation cardioverter defibrillators (ICDs) and to assess the usefulness of diagnostic tools. One hundred forty patients with 61 epicardial (43.6%) and 79 nonthoracotomy systems (56.4%) were followed for 25 +/- 19 months. A total of 18 (12.9%) lead related complications were documented. Complications of epicardial systems were detected in 10 patients (16.4%) during a follow-up time of 36 +/- 8 months: crinkling of patch electrodes in 6 patients (9.8%), insulation breakage of sensing electrodes in 2 patients (3.3%), and adapter defect in 2 patients (3.3%). Eight of the patients (10.1%) with transvenous-subcutaneous systems had lead related complications during a 13 +/- 6 months follow-up: fracture of the subcutaneous patch lead in 2 patients (2.5%), dislodgement of the right ventricular lead in 2 patients (2.5%), dislodgement of the superior vena cava lead in 2 patients (2.5%), insulation breakage of sensing electrodes in 1 patient (1.3%), and connector defect in 1 patient (1.3%). There was no significant difference in the incidence of lead related complications between epicardial and endocardial systems (P > 0.05). Fractures, dislodgements, and crinklings were documented within the first 8 +/- 5 months by regular chest X ray. Defects of insulation, adapter, or connector were detected 22 +/- 10 months after implantation and were associated with delivery of multiple inappropriate ICD therapies. An operative lead revision was indicated for 4 epicardial (6.6%) and 6 endocardial (7.6%) lead systems. CONCLUSIONS: Endocardial lead systems offer a similar long-term stability as compared to epicardial lead systems. Chest X ray is the most useful tool to detect lead fracture, dislodgment, and patch crinkling. Marker recordings or real-time electrograms have not been helpful in this series to identify patients with suspected lead defects prior to the experience of inappropriate ICD discharges.

Alloys↗

PubMed1995

Changes in the amplitude of endocardial electrograms following defibrillator discharge: comparison of two lead systems.

Changes in the amplitude of endocardial electrograms after an unsuccessful shock attempt have been demonstrated to cause failure of redetection of ventricular fibrillation in patients using an integrated sense-pace defibrillating lead system. Thus, the objective of this study was to compare the effects of defibrillator shocks on the amplitude of endocardial electrograms in 26 patients using two different nonthoracotomy systems, a previous lead (model 0062) or a redesigned version (model 0072). At implant, bipolar endocardial electrograms were obtained before each shock application, during initial detection and redetection of ventricular fibrillation in case the applied shock was unsuccessful, and during intervals of 5, 10, 20, 30, 60, and 120 seconds after each shock delivery. No significant difference was noted in endocardial amplitudes between the lead models 0062 and 0072 during baseline sinus rhythm (12.2 +/- 4.6 mV vs 11.4 +/- 3.8 mV), and during initial ventricular fibrillation (7.0 +/- 2.4 mV vs 7.6 +/- 2.3 mV). During redetection of ventricular fibrillation, however, there was a significant difference (P = 0.0006) in endocardial amplitudes (3.4 +/- 1.9 mV vs 6.6 +/- 2.3 mV) between both leads tested. Comparing lead models 0062 and 0072, marked differences were found in endocardial amplitudes during sinus rhythm 5, 10, and 20 seconds after successful arrhythmia termination: 2.8 +/- 1.9 mV vs 8.6 +/- 2.9 mV (P < 0.0001), 4.6 +/- 2.9 mV vs 9.2 +/- 3.2 mV (P = 0.0007), and 6.4 +/- 4.0 mV vs 10.5 +/- 3.6 mV (P = 0.01). At predischarge testing, failure of redetection of ventricular fibrillation was documented in two patients with the lead model 0062 requiring external defibrillation to restore sinus rhythm. These findings demonstrate a significant less postshock attenuation of the endocardial electrogram amplitudes during persistent ventricular fibrillation after an unsuccessful shock attempt as well as during sinus rhythm immediately following an effective shock delivery using the redesigned lead system model 0072 compared to the electrogram amplitudes obtained in patients using the previous lead model 0062.

Adult↗

PubMed1995

Intravenous adenosine during atrioventricular reentrant tachycardia: induction of atrial fibrillation with rapid conduction over an accessory pathway.

Adenosine is considered to be a safe agent for termination of orthodromic atrioventricular reentrant tachycardia in patients with accessory pathways. A case with initially successful accessory pathway ablation and without preexcitation during sinus rhythm is presented, in which intravenous adenosine (6 mg) during orthodromic tachycardia was followed by atrial fibrillation and sudden onset of preexcitation with subsequent rapid ventricular response with moderate hemodynamic compromise.

Adenosine↗

PubMed1995

Pacemaker function during radiofrequency ablation.

There are increasing numbers of radiofrequency current ablation procedures being reported. Selected patients have antitachycardia or antibradycardia pacemakers. The pacemaker behavior during and after ablation procedures differs widely. We report on the pacemaker reaction of 25 patients with 13 different devices, most with unipolar electrodes. Sensing failures were observed in 8 (32.0%) and pacing failures in 4 (16.0%) patients. Prolonged pauses and induction of tachyarrhythmias were observed. No pacemaker damage was seen although it is reported by other investigators. We recommend deactivation of implanted generators and an external bipolar pacing electrode. Manufacturers should focus their attention on this problem and protect the generators and their functions for 500 kHz radiofrequency current.

Adult↗

PubMed1995

Effects of nuclear magnetic resonance imaging on cardiac pacemakers.

Patients with cardiac pacemakers are currently restricted from nuclear magnetic resonance imaging (MRI). The aim of the study was to analyze the influence of MRI on new generation pacemakers. Tests were performed using a phantom model with seven dual chamber and two single chamber systems in a 0.5 Tesla MRI scanner. Monitoring by telemetry and oscillography were used during the standard clinical scan sequences as well as a pacemaker inquiry after each sequence. Spin echo, gradient echo, and fast field echo sequences were performed with the following stimulation modes: VVI, VVIR, VOO, DDD, DDDR, and DOO. On entering the static magnetic field, the reed switch was activated followed by asynchronous stimulation. The subsequent scan showed no influence on the stimulation function nor on the pacemaker program. Event counter function remained intact. Pacemakers with automatic mode switching to demand pacing or programmed inactivation of the reed switch were triggered in the dual chamber mode and were inhibited in the one chamber mode during the scan. Alterations of pacemaker program or rapid pacing were not observed. MRI scan could induce voltage as high as intracardiac signals, but the stimulation threshold of the heart was not reached. Thus, pacemakers should be programmed in the asynchronous mode during scan to avoid inhibition and trigger mechanism.

Acrylic Resins↗

PubMed1995

Echocardiographic imaging of coronary sinus diverticula and middle cardiac veins in patients with preexcitation syndrome: impact on radiofrequency catheter ablation of posteroseptal accessory pathways.

To determine the value of echocardiography for identifying coronary sinus (CS) diverticula and middle cardiac veins (MCVs) in patients with posteroseptal accessory pathways (PAPs), transthoracic (TTE) and transesophageal echocardiography (TEE) were performed in 18 consecutive patients with PAP and in 15 control subjects with left lateral accessory pathway before CS angiography. The size, shape, and location of CS diverticula and MCV were described and compared to angiography. TEE and angiography were concordant for the identification of diverticula (n = 5) and agreed for depicting MCV in 22 of the 27 cases. TTE revealed 4 of 5 diverticula and identified 4 of 27 MCV (P < 0.001). Fourteen MCV but no diverticula were found in the control subject. There was no significant difference between transesophageal and angiographic measurements for the width (23.5 +/- 4.9 vs 26.8 +/- 6.6 mm) and height (13.5 +/- 3.8 vs 15.7 +/- 3.4 mm) of the diverticula, and the width (3.5 +/- 0.7 vs 3.7 +/- 0.6 mm) of MCV. TEE underestimated the length of the MCV (12.0 +/- 1.8 vs 27.2 +/- 6.0, P < 0.001). Delivery of radiofrequency energy within the neck of a diverticulum or within an MCV was successful in 5 of 5, and 6 of 13 cases in patients with PAPs, respectively. In conclusion, echocardiography was as reliable as angiography for detecting and describing CS diverticula and MCV in patients with preexcitation syndrome. Echocardiography is recommended prior to electrophysiological study because it may simplify radiofrequency catheter ablation.

Adult↗

PubMed1995

Slowing of the ventricular rate during atrial fibrillation by ablation of the slow pathway of AV nodal reentrant tachycardia.

INTRODUCTION: The mechanisms whereby radiofrequency catheter modification of AV nodal conduction slows the ventricular response are not well defined. Whether a successful modification procedure can be achieved by ablating posterior inputs to the AV node or by partial ablation of the compact AV node is unclear. We hypothesized that ablation of the well-defined slow pathway in patients with AV nodal reentrant tachycardia would slow the ventricular response during atrial fibrillation. METHODS AND RESULTS: In 34 patients with dual AV physiology and inducible AV nodal reentrant tachycardia, atrial fibrillation was induced at baseline and immediately after successful slow pathway ablation and at 1-week follow-up. The minimal, maximal, and mean RR intervals during atrial fibrillation increased from 353 +/- 76, 500 +/- 121, and 405 +/- 91 msec to 429 +/- 84 (P < 0.01), 673 +/- 161 (P < 0.01), and 535 +/- 98 msec (P < 0.01), respectively. These effects remained stable during follow-up at 1 week. The AV block cycle length increased from 343 +/- 68 msec to 375 +/- 60 msec (P < 0.05) immediately and to 400 +/- 56 msec (P < 0.01) at 1-week follow-up. The effective refractory period of the AV node prolonged from 282 +/- 83 msec to 312 +/- 89 msec and to 318 +/- 81 msec after 1 week (P < 0.05), respectively. CONCLUSION: This study shows a decrease in ventricular response to pacing-induced atrial fibrillation after ablation of the slow pathway in patients with AV nodal reentrant tachycardia. Since the AV nodal conduction properties could be defined, this study supports the hypothesis that the main mechanism of AV nodal modification in chronic atrial fibrillation is caused by ablation of posterior inputs to the AV node.

Atrial Fibrillation↗

PubMed1995

[Cerebrogenic ECG changes after severe subarachnoid hemorrhage from an internal carotid artery aneurysm--differential diagnosis of acute myocardial infarct].

ECG-changes simulating acute posterior myocardial infarction were observed in a 62-year-old woman 16 days after acute subarachnoid hemorrhage. An acute myocardial ischemia was excluded by enzyme laboratory tests and by coronary angiography. The transient ECG-changes can be explained by short-term spasms of small distal arterioles in the heart, which were affected by a derangement of autonomic function. The present case demonstrates ECG-changes in a patient with subarachnoid hemorrhage very late after the acute event. Therefore, patients with intracranial hemorrhage should have a prolonged electrocardiographical aftercare. ECG-changes in patients with subarachnoid hemorrhage were discussed as a specific parameter describing the degree of intracranial damage and as a predictive value for a poor outcome. Because of ventricular arrhythmias and the occurrence of sudden cardiac death in patients with subarachnoid hemorrhage critical care monitoring should be performed after detection of new ECG-changes.

Autonomic Nervous System↗

PubMed1995

[Prognostic value of signal averaged ECG in dilated cardiomyopathy with spontaneous and induced ventricular tachyarrhythmias].

UNLABELLED: Ventricular late potentials in signal-averaged ECG are a predictor of ventricular tachyarrhythmias in patients with coronary artery disease. The role of signal-average ECG in non-ischemic dilated cardiomyopathy has not been defined yet. We studied the prognostic impact of an abnormal signal-averaged ECG in 31 patients with non-ischemic dilated cardiomyopathy. All signal-averaged ECG recordings were analyzed by time-domain analysis as well as by frequency analysis with spectrotemporal mapping. RESULTS: In 13 (42%) patients time domain analysis and in 9 (29%) patients frequency analysis was found to be abnormal. During follow-up (13 +/- 7 months) seven (23%) patients developed spontaneous ventricular tachyarrhythmias. The mean ejection fraction and the results of programmed ventricular stimulation did not differ significantly between patients with and without clinical episodes. Abnormal time domain analysis was found in five (71%) patients with and in eight (33%) patients without spontaneous tachyarrhythmias (p = 0.07), and abnormal frequency analysis in 3 (43%) patients versus 6 (25%) patients (p = 0.36). The low-amplitude-signal duration was significantly increased in patients with tachyarrhythmias (p = 0.008). Ventricular tachyarrhythmias occurred in 38% of patients with abnormal time domain analysis and in 33% of patients with abnormal frequency analysis. In patients with normal signal-averaged ECG the incidence reached 11% and 18%. For time-domain analysis the sensitivity was 71%, specificity 67%, positive predictive value 38%, and negative predictive value 89%, for spectrotemporal mapping 43%, 75%, 33%, and 82%, respectively. The incidence of electrophysiologically inducible ventricular tachyarrhythmias in patients with abnormal signal-averaged ECG exceeded that in patients with normal findings. CONCLUSION: In patients with non-ischemic dilated cardiomyopathy a normal signal-averaged ECG is associated with a reduced occurrence of ventricular tachyarrhythmic events. Thus, signal-averaged ECG contributes to the evaluation of these patients. The negative predictive value exceeded the positive predictive value.

Adult↗