AIMS: It was the purpose of this study to determine the incidence of more than two AV nodal pathways in patients with AVNRT. METHODS AND RESULTS: In 78 consecutive patients with AV-nodal reentrant tachycardias (AVNRT) (50 females, 28 males, mean age 52.8 +/- 14.6 years), the number of sudden AH increases by 50 ms or more (AH-jump) was analysed during atrial extrastimulation. The incidence of two AV nodal pathways was accepted to be present in patients with AVNRT without an AH-jump ('smooth curve'). The following forms of tachycardia were induced: a typical AVNRT (slow-fast) in 67 patients, an atypical AVNRT (fast-slow) in 12 patients and a slow-slow-AVNRT in 4 patients. Five patients had two forms of AVNRT. 47 patients (60.3%) showed two AV nodal pathways, 27 patients (34.6%) had three AV-nodal pathways and 4 patients (5.1%) exhibited four AV-nodal pathways. For successful catheter ablation of AVNRT in patients with more than two pathways, more radiofrequency energy applications were required (9.2 +/- 6.3) compared with patients with only two pathways (6.7 +/- 4.8). Furthermore, in patients with more than two AV-nodal pathways, the catheter intervention resulted more frequently in a modulation of slow pathway conduction than in an ablation of the slow pathway(s). CONCLUSION: The incidence of more than two AV-nodal pathways in patients with AVNRT was unexpectedly high at about 40%. Thus, these tachycardias require a meticulous electrophysiological evaluation for successful ablation.

Adolescent↗

PubMed2002

[Biventricular stimulation therapy in patients with heart failure and tachycardic arrhythmias. Indications--results--prospects].

Biventricular pacing (BV-P) therapy is a new therapeutic approach in patients (pts) with drug refractory congestive heart failure; the beneficial effects of implantable cardioverter defibrillator (ICD) without BV-P therapy in patients (pts) with life-threatening ventricular tachyarrhythmias and impaired left ventricular (LV) function is associated with a relatively high cardiac and total mortality. We studied the follow-up of 410 pts (368 males, 42 females, mean age 57 +/- 11 years) after ICD implant. The LV function was assessed by the New York Heart functional class of heart failure (NYHA). Fifty pts (12%) were in NYHA I-II, 151 pts (37%) in NYHA II, 117 pts (29%) in NYHA II-III and 92 pts (22%) in NYHA III. Epicardial ICD implantation was performed in 209 pts (51%) and 201 pts (49%) received nonthoracotomy ICDs. Perioperatively (within 30 days after implant), 12 pts (3%) died, significantly more frequent after epicardial (11 of 209 pts, 5%) than after transvenous ICD implant (1 of 201 pts, < 1%)(p < 0.05). During a mean follow-up of 28 + 24 months (range < 1 to 114 months), 90 pts (23%) died: 9 pts (2%) died from sudden arrhythmic death and 5 pts (1%) suddenly, but probably not from arrhythmic causes; 55 pts (14%) died from cardiac causes (congestive heart failure, myocardial reinfarction) and 21 pts (5%) from noncardiac causes. 338 pts (82%) received ICD shocks (mean incidence 21 +/- 43 shocks per pt). Our data show that pts with LV dysfunction benefit from ICD therapy and that these pts survive for a considerable time after the first shock. However, survival is clearly influenced by the degree of left ventricular dysfunction and, in addition to ICD therapy, aggressive treatment of heart failure is necessary. Therefore, BV-P is a very promising concept to improve the worse prognosis in pts with moderate or severe congestive heart failure.

Adult↗

PubMed2001

[Current aspects of defibrillator therapy in congestive heart failure].

The beneficial effects of implantable cardioverter defibrillator (ICD) therapy in patients (pts) with life-threatening ventricular tachyarrhythmias and impaired left ventricular (LV) function is still unclear. We studied the follow-up of 410 pts (368 males, 42 females, mean age 57 +/- 11 years) after ICD implant. The LV function was assessed by the New York Heart Association functional class of heart failure (NYHA). Fifty pts (12%) were in NYHA I-II, 151 pts (37%) in NYHA II, 117 pts (29%) in NYHA II-III and 92 pts (22%) in NYHA III. Epicardial ICD implantation was performed in 209 pts (51%) and 201 pts (49%) received nonthoracotomy ICDs. Perioperatively (within 30 days after implant), 12 pts (3%) died, significantly more frequent after epicardial (11 of 209 pts, 5%) than after transvenous ICD implant (1 of 201 pts, < 1%) (p < 0.05). During a mean follow-up of 28 +/- 24 months (range < 1 to 114 months), 90 pts (23%) died: 9 pts (2%) died from sudden arrhythmic death and 5 pts (1%) suddenly, but probably not from arrhythmic causes; 55 pts (14%) died from cardiac causes (congestive heart failure, myocardial reinfarction) and 21 pts (5%) from noncardiac causes. The 3-year, 5-year and 7-year survival was 92% to 96% for arrhythmic mortality in NYHA class I, II and III compared to the 3-year survival of 94%, and a 5-year and 7-year survival of 84% in patients with NYHA class II-III. 338 pts (82%) received ICD shocks (mean incidence 21 +/- 43 shocks per pt); pts in NYHA class II (83%), class II-III (84%), class III (90%) received ICD discharges significantly more frequently than in class I-II (64%) (p < 0.05). Our data show that pts with LV dysfunction benefit from ICD therapy and that these pts survive for a considerable time after the first shock. However, survival is clearly influenced by the degree of left ventricular dysfunction and, in addition to ICD therapy, aggressive treatment of heart failure is necessary.

Aged↗

PubMed2001

Morphology discrimination: a beat-to-beat algorithm for the discrimination of ventricular from supraventricular tachycardia by implantable cardioverter defibrillators.

Inappropriate therapy of SVTs by ICDs remains a major clinical problem despite enhanced detection criteria like "sudden onset" and "rate stability" in third-generation devices. Electrogram morphology discrimination offers an additional approach to improve discrimination of supraventricular tachycardia (SVT) from ventricular tachycardia (VT). In a prospective, multicenter study, patients received an ICD with a beat-to-beat algorithm for morphological analysis of the intracardiac electrogram (Morphology Discrimination, MD). A nominal programmingfor standard enhancement criteria and morphology discrimination was required at implant. Electrogram storage of tachycardia episodes irrespective of delivery of therapy was used to assess sensitivity and specificity of the morphology algorithm alone and in combination with established detection criteria. During a 126 6-month follow-up, 886 episodes of device stored electrograms from 82 of 256patients were evaluated. Atnominal settings, the MD algorithm correctly identified 423 of 551 episodes as VT resulting in sensitivity of 77%. The classification of SVT was met in 239 of 335 episodes resulting in specificity of 71%. In combination with sudden onset, sensitivityincreased to 99.5% at the expense of specificity (48%). In conclusion, SVT-VT discrimination based on morphological analysis alone results in limited sensitivity and specificity. Programming the monitor mode allows individual assessment of the performance of this detection enhancement feature during clinical follow-up without compromising device safety. Only in patients with documented efficacy of morphology discrimination should this feature be subsequently activated.

Algorithms↗

PubMed2001

AV nodal pathways in the R-R interval histogram of the 24-hour monitoring ECG in patients with atrial fibrillation.

BACKGROUND: Patients with more than one AV nodal pathway show two and more peaks in the histogram of the R-R intervals of the Holter monitoring ECG during atrial fibrillation. It was the purpose of the present study to determine the number of patients showing more than one AV nodal pathway in a larger patient group with permanent atrial fibrillation by analyzing the Holter monitoring ECG. METHODS: 250 patients with permanent atrial fibrillation during Holter monitoring ECG were studied; 203 patients had structural heart disease. The number of peaks in the R-R interval histogram of each patient was determined. The distribution of the number of peaks in the R-R interval histogram in different patient groups was analyzed. RESULTS: 153 patients (61%) had one peak, 80 patients (32%) two peaks, 13 patients (5%) three peaks, and four patients (2%) four peaks, reflecting the number of different AV nodal pathways. In the different patient groups, in the patients with or without structural heart disease, with coronary heart disease, with a history of syncope, and in patients with a mean heart rate of more than 100/min, there was no significant difference in the distribution of the number of peaks in the R-R interval histogram. CONCLUSIONS: In more than one third of all patients with permanent atrial fibrillation there are two, three, or four AV nodal pathways. It is suggested that this number of different AV nodal pathways found in the studied group can be applied to all humans. 38.8% of all patients with permanent atrial fibrillation have more than one AV nodal pathway; 6.4% of all patients with atrial fibrillation would benefit from an ablation of AV nodal pathways with shorter refractory periods for reduction of the heart rate.

Adult↗

PubMed2001

[Cardiac arrhythmias in pregnancy].

Atrial premature beats are frequently diagnosed during pregnancy (PR), supraventricular tachycardia (SVT; atrial tachycardia, AV nodal reentrant tachycardia, circus movement tachycardia) less frequently. For acute therapy, electrical cardioversion with 50-100 J is indicated in all unstable patients (pts). In stable SVT the initial therapy includes the vagal maneuver to terminate breakthrough tachycardias. For short-term management, when the vagal maneuver fails, intravenous adenosine is the first-choice drug and may safely terminate the arrhythmia. For long-term therapy, beta-blocking agents with beta 1 selectivity are first-line drugs; class Ic agents or the class III drug sotalol (sot) are effective and therapeutic alternatives. Ventricular premature beats are also frequently present during PR and benign in most pts; however, malignant ventricular tachyarrhythmias (sustained ventricular tachycardia [VT], ventricular flutter [VFlut], ventricular fibrillation [VF]) were observed less frequently. Electrical cardioversion is necessary in all pts with a hemodynamically unstable situation and life-threatening ventricular tachyarrhythmias; in hemodynamically stable pts, initial therapy with ajmaline, procainamide or lidocaine is indicated. If prophylactic therapy is needed, beta-blocking agents with beta 1 selectivity are considered as first-choice drugs. If this therapy is ineffective, class Ic agents or sot can be considered. In pts with syncopal VT, VF, VFlut or aborted sudden death an implantable cardioverter-defibrillator is indicated. In pts with symptomatic bradycardia, a pacemaker can be implanted using echocardiography at any stage of PR. The treatment of the pregnant patient with cardiac arrhythmias requires important modification of the standard practice of arrhythmia management. The goal of therapy is to protect the patient and fetus through delivery, after which chronic or definitive therapy can be administered.

Anti-Arrhythmia Agents↗

PubMed2000

[Terminating supraventricular tachycardia with adenosine--comparing the effectiveness of 12 mg and 18 mg].

OBJECTIVES: This study was done to answer the question if intravenous application of 18 mg adenosine is superior to 12 mg adenosine for the termination of supraventricular tachycardias. PATIENTS AND METHODS: 31 patients (17 men, 14 women, mean age 53 +/- 15 years [range 15-76 years]) had electrophysiological tests. In 25 patients AV nodal reentrant tachycardias were induced during programmed stimulation, 6 patients had inducible AV reentrant tachycardias with an accessory pathway. After induction of the supraventricular tachycardia (mean rate 183 +/- 29/minute, range 115-240/minute), in each patient 12 or 18 mg adenosine was applied in a bolus for terminating of the tachycardia. After the second induction of the tachycardia, a dose of 18 or 12 mg adenosine was given. The different doses of adenosine were chosen in a randomized and prospective manner in a crossover design. RESULTS: In 25 of the 31 patients (81%) the tachycardia was terminated by 12 mg adenosine. In 29 of the 31 patients (94%) the induced tachycardia was terminated by the application of 18 mg adenosine (no significant difference). In one patient, the tachycardia cessation was observed after 12 mg adenosine, but not after 18 mg adenosine. In another patient the tachycardia was not terminated by either 12 mg or by 18 mg adenosine. The termination of the tachycardia was seen after 25 +/- 8 seconds (13-51 seconds) when 12 mg adenosine was given. After the application of 18 mg adenosine the tachycardia ended after 25 +/- 8 seconds (14-44 seconds) (not significant). The asystole directly after tachycardia termination was 976 +/- 63 milliseconds (540-1700 milliseconds) with 12 mg adenosine, and 1070 +/- 628 milliseconds (530-4000 milliseconds) after the application of 18 mg adenosine (not significant). The longest asystole after termination of a tachycardia by 18 mg adenosine was 9.03 seconds. In one patient the tachycardia was reinitiated by spontaneous atrial extrasystoles after 12 mg adenosine, and reinduction of tachycardia was seen twice after 18 mg adenosine. After the administration of 18 mg adenosine, atrial fibrillation was observed in one patient. No serious complication occurred. CONCLUSIONS: In AV nodal reentrant tachycardias and AV reentrant tachycardias with an accessory pathway, which can not be terminated by the administration of adenosine in a dose of 12 mg, the tachycardia can be terminated more effectively by the application of 18 mg adenosine.

Adenosine↗

PubMed2000

[Tachycardia with wide QRS complex in a young man].

Explore the source record for details and available documents.

Adult↗

PubMed2000

[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↗

PubMed2000

[Guidelines for ergometry. German Society of Cardiology--Heart and Cardiovascular Research].

Explore the source record for details and available documents.

Electrocardiography↗

PubMed2000

Assessment of the chronotropic response at the anaerobic threshold: an objective measure of chronotropic function.

The evaluation of the heart rate response to exercise is important for the diagnosis of chronotropic incompetence and the assessment of a rate responsive algorithm of sensor-controlled pacemakers. The aim of the present study was to examine a classification of the chronotropic response at an individually moderate exercise level. Sixteen pacemaker patients (patient group, age 62.9 +/- 7.6 years) with sick sinus syndrome and 15 age-matched healthy subjects (control group, age 57.6 +/- 9.4 years) underwent a maximum cardiopulmonary exercise test on a treadmill after a protocol with individually selected incremental steps. To analyze the patients' intrinsic heart rate response, the rate responsive mode of the pacemaker was switched off. Chronotropic incompetence was diagnosed in eight patients whose maximal heart rate was < 80% of the age-predicted heart rate. The heart rate at the anaerobic threshold was significantly lower in the chronotropically incompetent subgroup than in the chronotropically competent patients and the healthy subjects (85.9 +/- 6.6 beats/min vs 100.3 +/- 9.9 beats/min and 112.9 +/- 11.7 beats/min, respectively). The chronotropic slope of the heart rate reserve as a function of the metabolic reserve was significantly higher in the control group than in the patient groups with either mild or severe chronotropic incompetence (0.94 +/- 0.17 vs 0.64 +/- 0.08 and 0.43 +/- 0.14, respectively). Furthermore, the chronotropically incompetent response could be divided into a linear type with and without a threshold, an exponential, and a logarithmic type. The anaerobic threshold was an objectively detectable breakpoint at an individually moderate exercise level that could be used for characterization of chronotropic function. At the anaerobic threshold, a physiological heart rate response was about 220--age--50 beats/min. A deviation of more than 10 beats/min below this physiological value characterized chronotropic incompetence.

Algorithms↗

PubMed2000

Impact of biventricular pacing on mortality in a randomized crossover study of patients with heart failure and ventricular arrhythmias.

Biventricular (BV) pacing is under clinical investigation for the treatment of heart failure. Its impact on mortality is unknown. Patients with heart failure and ventricular tachyarrhythmias received an implantable cardioverter defibrillator with BV pacing capability. Patients were randomized 1:1 to BV pacing or no pacing, then crossed over to the alternate mode after 3 months. All-cause mortality was measured in each arm up to the point of crossover. Fifteen of 222 patients died between implant and crossover. Five patients died while programmed to BV pacing and 19 died while programmed to no pacing. Survival in the BV pacing arm was 93 +/- 4% versus 86 +/- 6% in the no pacing arm (P = 0.18). In a patient population with symptomatic heart failure and ventricular arrhythmias, BV pacing does not appear to be associated with excess mortality. Larger and longer studies will be needed to determine if BV pacing confers a survival benefit.

Aged↗

PubMed2000

Performance of a new steroid-eluting coronary sinus lead designed for left ventricular pacing.

The Ventak CHF/CONTAK CD Biventricular Pacing Study is a prospective randomized trial to examine the safety and efficacy of biventricular (BV) pacing in patients with standard indications for an ICD, symptomatic heart failure, a LVEF < or = 0.35, and a QRS > or = 120 ms. Patients underwent implantation of a BV pacing and sensing system with backup defibrillation capability, which includes a steroid-eluting coronary venous lead that is advanced into the coronary venous vasculature by over-the-wire techniques. LV pacing threshold, BV impedance, and BV R wave amplitude were measured in 58 consecutive patients. Using a percutaneous over-the-wire insertion technique, steroid-eluting coronary venous leads were associated with satisfactory mean LV pacing threshold, BV impedance, and BV R wave amplitude acutely up to 4 months after implantation. Pacing threshold stabilized 2 weeks after lead implantation and sensing threshold remained stable from the time of implant.

Cardiac Surgical Procedures↗