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Indian Pacing and Electrophysiology... Aug 2008In atrioventricular nodal re-entrant tachycardias (AVNRT), the achievement of Junctional Rhythms (JR) during Radiofrequency Ablation (RF) is a sensitive but non-specific...
Importance of the relationship between sinus cycle length and junctional rhythm cycle length (occured during radiofrequency ablation) in predicting the successful modification of the slow pathway in Atrioventricular Nodal Re-entrant Tachycardias.
BACKGROUND
In atrioventricular nodal re-entrant tachycardias (AVNRT), the achievement of Junctional Rhythms (JR) during Radiofrequency Ablation (RF) is a sensitive but non-specific marker of success. Our aim is to analyze prospectively the predictors of non-inducibility of AVNRT, focusing on the characteristics of the JR.
METHODS
We included 75 patients with reproducibly inducible AVNRT. Ablation was performed following an electro-anatomical approach. After each application, the induction protocol was repeated.
RESULTS
A total of 341 applications were performed. Although the achievement of >/=1 JR was necessary to obtain the non-inducibility, and the cumulative number of junctional beats (CJB) was higher in effective applications, no CJB cut-off was associated with a success rate higher than 75%. After the observation of a significant correlation between the sinus cycle length (CL) pre-RF and the CL of the JR (JR-CL) (c=0.52; p<0.001), the sinus CL pre-RF/JR-CL ratio (CL-ratio) adequately differentiated the successful vs. unsuccessful applications: 1.41+/-0.23 vs. 1.17+/-0.2 (p<0.001). In a multivariate analysis, a CBJ 11 (p<0.001) and a CL-ratio 1.25 (p<0.001) were found to be the only independent predictors of success. The combination of >/= 11 of CJB with a CL ratio >/= 1.25 achieved non-inducibility in 97% of our patients.
CONCLUSION
1) The specificity of the occurrence of JR as a marker of the successful ablation of AVNRT is increased by the CL-ratio. 2) The achievement of >/= 11 of CJB with a CL ratio >/= 1.25 predicts non-inducibility in almost all patients.
PubMed: 18679524
DOI: No ID Found -
The Annals of Thoracic Surgery Jun 2007Symptoms are widely used as a means of assessment and follow-up of patients with atrial fibrillation. This study assessed the correlation between symptoms and cardiac...
BACKGROUND
Symptoms are widely used as a means of assessment and follow-up of patients with atrial fibrillation. This study assessed the correlation between symptoms and cardiac rhythm in patients being evaluated for operative therapy for atrial fibrillation.
METHODS
Seven days of preoperative continuous outpatient home electrocardiographic monitoring was performed on 50 patients with symptomatic atrial fibrillation. Cardiac rhythm was continuously monitored automatically, while patients recorded their symptoms electronically. Correlations were then drawn between symptomatic events and actual rhythm, and between atrial fibrillation episodes and symptoms.
RESULTS
Fifty patients (37 men) with symptomatic atrial fibrillation were monitored for a combined 356 days (mean, 7.1 days). Patients were average age of 69 years old. Intermittent atrial fibrillation was reported by 36 patients, and 14 believed their atrial fibrillation was continuous. During monitoring, all patients had periods of both atrial fibrillation and normal sinus rhythm. Of the 552 documented episodes of atrial fibrillation, 467 (85%) were asymptomatic, and 85 (15%) episodes were symptomatic. Patients indicated that they experienced atrial fibrillation symptoms 163 times. Of the 163 symptomatic events, 85 (52%) were actual atrial fibrillation, 64 (42%) were sinus rhythm, and 14 (6%) were other rhythms. The ability of an individual patient to accurately identify atrial fibrillation ranged from 0% to 100%.
CONCLUSIONS
Patient-reported symptoms of atrial fibrillation had poor correlation with actual rhythm. The lack of correlation between symptoms and rhythm underscores the importance of continuous home monitoring for accurately quantifying preoperative atrial fibrillation burden and for postoperative follow-up.
Topics: Adult; Aged; Atrial Fibrillation; Electrocardiography, Ambulatory; Female; Humans; Male; Middle Aged; Preoperative Care
PubMed: 17532409
DOI: 10.1016/j.athoracsur.2007.02.084 -
Physiological Reports Jan 2021The presence of bradycardic arrhythmias during volitional apnea at altitude may be caused by chemoreflex activation/sensitization. We investigated whether...
The presence of bradycardic arrhythmias during volitional apnea at altitude may be caused by chemoreflex activation/sensitization. We investigated whether bradyarrhythmic episodes became prevalent in apnea following short-term hypoxia exposure. Electrocardiograms (ECG; lead II) were collected from 22 low-altitude residents (F = 12; age=25 ± 5 years) at 671 m. Participants were exposed to normobaric hypoxia (SpO ~79 ± 3%) over a 5-h period. ECG rhythms were assessed during both free-breathing and maximal volitional end-expiratory and end-inspiratory apnea at baseline during normoxia and hypoxia exposure (20 min [AHX]; 5 h [HX5]). Free-breathing HR became elevated at AHX (78 ± 10 bpm; p < 0.0001) and HX5 (80 ± 12 bpm; p < 0.0001) compared to normoxia (68 ± 10 bpm), whereas apnea caused significant bradycardia at AHX (nadir end-expiratory -17 ± 14 bpm; p < 0.001) and HX5 (nadir end-expiratory -19 ± 15 bpm; p < 0.001), but not during normoxia (nadir end-expiratory -4 ± 13 bpm), with no difference in bradycardia responses between apneas at AHX and HX5. Conduction abnormalities were noted in five participants during normoxia (Premature Ventricular Contraction, Sinus Pause, Junctional Rhythm, Atrial Foci), which remained unchanged during apnea at AHX and HX5 (Premature Ventricular Contraction, Premature Atrial Contraction, Sinus Pause). End-inspiratory apneas were overall longer across conditions (normoxia p < 0.05; AHX p < 0.01; HX5 p < 0.001), with comparable HR responses to end-expiratory and fewer occurrences of arrhythmia. While short-term hypoxia is sufficient to elicit bradycardia during apnea, the occurrence of arrhythmias in response to apnea was not affected. These findings indicate that previously observed bradyarrhythmic events in untrained individuals at altitude only become prevalent following chronic hypoxia specificlly.
Topics: Adult; Apnea; Arrhythmias, Cardiac; Bradycardia; Canada; Chemoreceptor Cells; Female; Heart Conduction System; Heart Rate; Humans; Hypoxia; Male
PubMed: 33426815
DOI: 10.14814/phy2.14703 -
Biomedicines Mar 2023Respiratory sinus arrhythmia (RSA) denotes decrease of cardiac beat-to-beat intervals (RRI) during inspiration and RRI increase during expiration, but an inverse pattern...
BACKGROUND
Respiratory sinus arrhythmia (RSA) denotes decrease of cardiac beat-to-beat intervals (RRI) during inspiration and RRI increase during expiration, but an inverse pattern (termed negative RSA) was also found in healthy humans with elevated anxiety. It was detected using wave-by-wave analysis of cardiorespiratory rhythms and was considered to reflect a strategy of anxiety management involving the activation of a neural pacemaker. Results were consistent with slow breathing, but contained uncertainty at normal breathing rates (0.2-0.4 Hz).
OBJECTIVES AND METHODS
We combined wave-by-wave analysis and directed information flow analysis to obtain information on anxiety management at higher breathing rates. We analyzed cardiorespiratory rhythms and blood oxygen level-dependent (BOLD) signals from the brainstem and cortex in 10 healthy fMRI participants with elevated anxiety.
RESULTS
Three subjects with slow respiratory, RRI, and neural BOLD oscillations showed 57 ± 26% negative RSA and significant anxiety reduction by 54 ± 9%. Six participants with breathing rate of ~0.3 Hz showed 41 ± 16% negative RSA and weaker anxiety reduction. They presented significant information flow from RRI to respiration and from the middle frontal cortex to the brainstem, which may result from respiration-entrained brain oscillations, indicating another anxiety management strategy.
CONCLUSIONS
The two analytical approaches applied here indicate at least two different anxiety management strategies in healthy subjects.
PubMed: 37189642
DOI: 10.3390/biomedicines11041028 -
The American Journal of Cardiology May 2019Atrial fibrillation (AF) is a significant cause of cardioembolic strokes. AF is often symptomless and intermittent, making its detection challenging. The aim of this...
Atrial fibrillation (AF) is a significant cause of cardioembolic strokes. AF is often symptomless and intermittent, making its detection challenging. The aim of this study was to assess the possibility to use a chest strap (Suunto Movesense) to detect AF both by cardiologists and automated algorithms. A single channel electrocardiogram (ECG) from a chest strap of 220 patients (107 AF and 111 sinus rhythm SR with 2 inconclusive rhythms) were analyzed by 2 cardiologists (Doc1 and Doc2) and 2 different algorithms (COSEn and AFEvidence). A 3-lead Holter served as the gold standard ECG for rhythm analysis. Both cardiologists evaluated the quality of the chest strap ECG to be superior to the quality of the Holter ECG; p <0.05/p <0.001 (Doc1/Doc 2). Accurate automated algorithm-based AF detection was achieved with sensitivity of 95.3%/96.3% and specificity of 95.5/98.2% with 2 AF detection algorithms from chest strap and 93.5%/97.2% and 98.2%/95.5% from Holter, respectively. P waves were detectable in 93.7% (Doc1) and 94.6% (Doc2) of the cases from the chest strap ECG with sinus rhythm and 98.2% (Doc1) and 95.5% (Doc2) from the Holter (p = n.s). In conclusion, the ECGs from both methods enabled AF detection by a cardiologist and by automated algorithms. Both methods studied enabled P-wave detection in sinus rhythm.
Topics: Aged; Algorithms; Atrial Fibrillation; Brain Ischemia; Case-Control Studies; Diagnosis, Computer-Assisted; Electrocardiography; Equipment Design; Female; Follow-Up Studies; Humans; Male; Middle Aged; Prospective Studies; Reproducibility of Results; Thorax
PubMed: 30878151
DOI: 10.1016/j.amjcard.2019.02.028 -
Japanese Heart Journal Sep 1996During A-V nodal reentry the impulse is supposed to travel through two distinct pathways in the A-V nodal junction, called slow and fast pathways. Clinically, catheter... (Review)
Review
During A-V nodal reentry the impulse is supposed to travel through two distinct pathways in the A-V nodal junction, called slow and fast pathways. Clinically, catheter ablation of these pathways has been very successful in abolishing A-V nodal reentrant tachycardias. So-called double potentials have been used as a marker for the slow pathway, and the occurrence of accelerated junctional rhythms (AJR) following ablation is an indicator of successful destruction of the slow pathway. In Langendorff, blood-perfused porcine and canine hearts, extensive mapping of extracellular potentials, combined with microelectrode recordings, was carried out to answer the following questions: 1) what is the origin of double extracellular potentials? 2) what causes post-ablation AJR? 3) what is the activation pattern of the AV junction during ventricular echoes? 1) Two types of double potentials were found: a low-frequency component followed by a high-frequency deflection, the LH potential was caused by asynchronous activation of the sinus septum above the coronary sinus and the region between the coronary sinus orifice and tricuspid annulus, where the L component is a far field potential. HL potentials (high-frequency deflection followed by a low frequency component) were caused by asynchronous activation of atrial cells and cells with AV nodal characteristics at the same location. These cells were present around the entire tricuspid annulus, and were not part of the compact node. The proximity of LH potentials to the slow pathway is probably serendipity, HL potentials could represent the slow pathway. 2) Two types of AJR could be initiated both by application of radiofrequency energy and by heat: a regular rhythm that progressively accelerated and an irregular rhythm. The discrete sites where heat application induced AJR did not correlate with areas showing double potentials, nor with exit regions during ventricular pacing. They were close to the compact node and the underlying mechanism was accelerated phase 4 depolarization in single or multiple foci, the latter accounting for irregular AJR. The association between presence of AJR and successful slow pathway ablation is probably also serendipity. 3) During ventricular pacing, two separate areas of earliest atrial activity were found. When ventricular echoes were induced by premature stimulation, the retrograde impulse activated both atrial exit sites and still returned in the ventricles as an echo. Thus, no evidence was found that atrial tissue forms part of the reentrant circuit.
Topics: Animals; Atrioventricular Node; Catheter Ablation; Dogs; Electrophysiology; Heart Conduction System; Tachycardia, Atrioventricular Nodal Reentry; Tachycardia, Ectopic Junctional
PubMed: 8973390
DOI: 10.1536/ihj.37.785 -
Wilderness & Environmental Medicine 2001Hypothermia is known to adversely affect the electrocardiogram (ECG) in many cases. This study set out to determine the incidence of defined cardiac dysrhythmias, J...
OBJECTIVE
Hypothermia is known to adversely affect the electrocardiogram (ECG) in many cases. This study set out to determine the incidence of defined cardiac dysrhythmias, J waves, and conduction abnormalities in urban hypothermia.
METHODS
A prospective, multicenter study was carried out to determine the incidence of defined cardiac rhythms in patients suffering from accidental urban hypothermia. The ECGs were independently analyzed by 2 of the authors and placed into 1 of 6 rhythm categories.
RESULTS
Seventy-three ECGs were analyzed. Normal sinus rhythm was the most common rhythm (41%). Overall mortality was 36% (26/73). J waves occurred in 36% of survivors and 38% of non-survivors and were, therefore, not prognostic. Shivering artifact was present in 66% of survivors and 38% of nonsurvivors. Although there was no statistically significant association between J waves and survival (P = .21), the presence of shivering artifact was associated with survival in severe hypothermia (P = .047). Atrial fibrillation and junctional bradycardia were both associated with high mortality.
CONCLUSIONS
This study confirms that the ECG is abnormal in the majority of patients suffering from accidental hypothermia. J waves do not appear to be independently prognostic in hypothermia. The results suggest that the inability to mount a shivering response may be associated with a poorer outcome; this finding requires further study.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Arrhythmias, Cardiac; Electrocardiography; Emergency Treatment; Female; Humans; Hypothermia; Incidence; Male; Middle Aged; Prospective Studies; Scotland; Survival Analysis
PubMed: 11769917
DOI: 10.1580/1080-6032(2001)012[0232:teih]2.0.co;2 -
Critical Care and Resuscitation :... Mar 2002To review the diagnosis and management of cardiac arrhythmias in a two-part presentation.
OBJECTIVE
To review the diagnosis and management of cardiac arrhythmias in a two-part presentation.
DATA SOURCES
Articles and published peer-review abstracts on tachycardias and bradycardias.
SUMMARY OF REVIEW
Normal cardiac rhythm originates from impulses generated within the sinus node. These impulses are conducted to the atrioventricular node where they are delayed before they are distributed to the ventricular myocardium via the His-Purkinje system. Abnormalities in cardiac rhythm are caused by disorders of impulse generation, conduction or a combination of the two and may be life threatening due to a reduction in cardiac output or myocardial oxygenation. Cardiac arrhythmias are commonly classified as tachycardias (supraventricular or ventricular) or bradycardias. The differentiation between supraventricular and ventricular tachycardias usually requires an assessment of atrial and ventricular rhythms and their relationship to each other. In the critically ill patient the commonest tachycardia is sinus tachycardia and treatment generally consist of management of the underlying disorder. Other supraventricular tachycardias (SVTs) include, atrial flutter, atrial fibrillation and paroxysmal supraventricular tachycardia (PSVT) all of which may require cardioversion, although to maintain sinus rhythm, antiarrhythmic therapy is often needed. Adenosine is useful in management and treatment many SVTs although its use in PSVT with Wolff-Parkinson-White syndrome is hazardous. Multifocal atrial tachycardia is a characteristic supraventricular tachycardia found in the critical ill patient. While it usually responds to intravenous magnesium sulphate, its management also requires removal of various precipitating factors. Ventricular tachycardia (VT) and ventricular fibrillation (VF) require urgent cardioversion and defibrillation respectively. Torsade de pointes should be differentiated from these ventricular arrhythmias as antiarrhythmic therapy may be contraindicated.
CONCLUSIONS
Supraventricular and ventricular tachycardias in the critically ill patient often have underlying disorders that precipitate their development (e.g. hypokalaemia, hypomagnesaemia, anti-arrhythmic proarrhythmia, myocardial ischaemia, etc). While antiarrhythmic therapy and cardioversion or defibrillation may be required to achieve sinus rhythm, correction of the associated abnormalities is also required.
PubMed: 16573402
DOI: No ID Found -
Revista Espanola de Cardiologia Aug 1997We present two families with atrial fibrillation in 20 of 50 members, during three generations, with known cardiac rhythms, in order to communicate their infrequent...
INTRODUCTION AND OBJECTIVE
We present two families with atrial fibrillation in 20 of 50 members, during three generations, with known cardiac rhythms, in order to communicate their infrequent existence and the most relevant clinical facts.
METHOD
Clinical situation, evolution, ECG and ECHO findings, treatments and complications related with the disease are investigated.
RESULTS
The presence of atrial fibrillation in 20 members is demonstrated, although one of them was on sinus rhythm at the time of the study; 3 patients had left ventricular enlargement on the ECHO study; the clinical situation was good in all patients except two who died because of complications related to the arrythmia and a third patient that had a brain stroke. The patients received different treatments because they where controlled by different physicians; the possible lethal proarrythmic effect in such cases must be taken into account.
CONCLUSION
Familiar atrial fibrillation is a very infrequent arrythmia, usually well tolerated, that follows a dominant autosomic hereditary pattern. The use of antiagregants is advised because of the risk of embolism, or the use of anticoagulants in the presence of associated risk factors. Electric cardioversion has been show not be useful. The possible proarrythmic effect of some antiarrythmic agents, used in the control of cardiac frequency, must be taken into account.
Topics: Adolescent; Adult; Aged; Anti-Arrhythmia Agents; Anticoagulants; Atenolol; Atrial Fibrillation; Digoxin; Echocardiography; Electrocardiography; Female; Humans; Male; Middle Aged; Pedigree; Propafenone
PubMed: 9340695
DOI: 10.1016/s0300-8932(97)73262-7 -
Heart Rhythm Apr 2019The apamin-sensitive small-conductance calcium-activated K (SK) current I modulates automaticity of the sinus node. I blockade by apamin causes sinus bradycardia.
BACKGROUND
The apamin-sensitive small-conductance calcium-activated K (SK) current I modulates automaticity of the sinus node. I blockade by apamin causes sinus bradycardia.
OBJECTIVE
The purpose of this study was to test the hypothesis that I modulates ventricular automaticity.
METHODS
We tested the effects of apamin (100 nM) on ventricular escape rhythms in Langendorff-perfused rabbit ventricles with atrioventricular block (protocol 1) and on recorded transmembrane action potential of pseudotendons of superfused right ventricular endocardial preparations (protocol 2).
RESULTS
All preparations exhibited spontaneous ventricular escape rhythms. In protocol 1, apamin decreased the atrial rate from 186.2 ± 18.0 bpm to 163.8 ± 18.7 bpm (N = 6; P = .006) but accelerated the ventricular escape rate from 51.5 ± 10.7 bpm to 98.2 ± 25.4 bpm (P = .031). Three preparations exhibited bursts of nonsustained ventricular tachycardia and pauses, resulting in repeated burst termination pattern. In protocol 2, apamin increased the ventricular escape rate from 70.2 ± 13.1 bpm to 110.1 ± 2.2 bpm (P = .035). Spontaneous phase 4 depolarization was recorded from the pseudotendons in 6 of 10 preparations at baseline and in 3 in the presence of apamin. There were no changes of phase 4 slope (18.37 ± 3.55 mV/s vs 18.93 ± 3.26 mV/s, N = 3; P = .231, ), but the threshold of phase 0 activation (mV) reduced from -67.97 ± 1.53 to -75.26 ± 0.28 (P = .034). Addition of JTV-519, a ryanodine receptor 2 stabilizer, in 5 preparations reduced escape rate back to baseline.
CONCLUSION
Contrary to its bradycardic effect in the sinus node, I blockade by apamin accelerates ventricular automaticity and causes repeated nonsustained ventricular tachycardia in normal ventricles. ryanodine receptor 2 blockade reversed the apamin effects on ventricular automaticity.
Topics: Action Potentials; Animals; Apamin; Atrioventricular Block; Purkinje Fibers; Rabbits; Ryanodine Receptor Calcium Release Channel; Small-Conductance Calcium-Activated Potassium Channels; Tachycardia, Ventricular
PubMed: 30445170
DOI: 10.1016/j.hrthm.2018.10.033