Cardiovascular Disease Update: Bradyarrhythmias.

Bradyarrhythmia (bradycardia) is a heart rate lower than 60 beats/min. It can be due to sinus, atrial, or junctional bradycardia or to a problem with the conduction system (eg, an atrioventricular block). Asymptomatic bradycardia is common, especially among trained athletes or during sleep. Bradycardia symptoms can include syncope, dizziness, chest pain, dyspnea, or fatigue. It is important to determine during the evaluation if bradycardia is the cause of the patient's symptoms. In the acute setting, symptomatic patients should be treated with atropine. Percutaneous pacing can be used as a bridge to definitive treatment. The only therapy for persistent bradycardia is placement of a permanent pacemaker. Symptomatic patients with sick sinus syndrome and high second- or third-degree atrioventricular blocks require placement of permanent pacemakers.

Trigeminal cardiac reflex: new thinking model about the definition based on a literature review.

Trigeminocardiac reflex (TCR) is a brainstem reflex that manifests as sudden onset of hemodynamic perturbation in blood pressure (MABP) and heart rate (HR), as apnea and as gastric hypermotility during stimulation of any branches of the trigeminal nerve. The molecular and clinical knowledge about the TCR is in a constant growth since 1999, what implies a current need of a review about its definition in this changing context. Relevant literature was identified through searching in PubMed (MEDLINE) and Google scholar database for the terms TCR, oculocardiac reflex, diving reflex, vasovagale response. The definition of the TCR varies in clinical as well as in research studies. The main difference applies the required change of MABP and sometimes also HR, which most varies between 10% and 20%. Due to this definition problem, we defined, related to actual literature, 2 major (plausibility, reversibility) and 2 minor criteria (repetition, prevention) for a more proper identification of the TCR in a clinical or research setting. Latest research implies that there is a need for a more extended classification with 2 additional subgroups, considering also the diving reflex and the brainstem reflex. In this review, we highlighted criteria for proper definition and classification of the TCR in the light of increased knowledge and present a thinking model to overcome this complexity. Further we separately discussed the role of HR and MABP and their variation in this context. As another subtopic we gave attention to is the chronic TCR; a variant that is rarely seen in clinical medicine.

[ESC Guidelines on Pacemaker Therapy 2013: what is new and relevant for daily practice?]. / ESC-Leitlinien zur Herzschrittmachertherapie 2013: Was ist neu und wichtig für die Praxis?

The European Society of Cardiology (ESC) and the European Heart Rhythm Association (EHRA) published new guidelines for pacemaker and cardiac resynchronisation therapy in June 2013. The most important recommendations for daily clinical practice of pacemaker therapy firstly refer to the diagnosis of bradycardia and bradycardia-symptom-correlation. Bradycardia is classified into persistent and intermittent, the latter with and without documentation of spontaneous bradycardia. Evidence for pacemaker therapy depends on the quality of bradycardia-symptom-correlation. The indication for pacing in sick-sinus-syndrome and AV block is significantly simplified and the use of implantable loop-recording in syncope of unknown origin encouraged. If loop recorders document long asymptomatic pauses, the authors felt that an indication for pacing exists if pauses exceed 6 sec. Other newly defined pacing indications are syncope in bundle branch block and very long PR (> 300 ms), particularly in older patients and those with structural heart disease. New insights and recommendations are further provided for complications of pacemaker therapy, right ventricular pacing sites, perioperative anticoagulation, pacing and magnetic resonance imaging and remote monitoring. In conclusion, the new ESC guidelines elegantly summarize results of new trials and studies in bradycardia and pacemaker therapy and provide valuable recommendations for daily practice.

Tratamiento de las arritmias / Treatment of arrhythmias

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[Managing bradycardia in adults]. / Conduite a tenir devant une bradycardie de l'adulte.

Bradycardia represents a common cause of requirement for specialist advice and it looks sometimes difficult to evaluate its pathological criteria and its medical management. The authors remind the physiological mechanisms and their aetiologies, cardiac or not. Many complementary exams can be employed but a rigorous strategy is necessary, based on the use of electrocardiogram, Holter ECG, implantable loop recorder, stress test, cardiac echography, tilt testing, electrophysiological study. Once the diagnostic established, the next fundamental step consists on a rigorous evaluation of severity in order to recognize the real urgency which require an hospitalization and to initiate rapidly the most appropriate treatment, sometimes before having the complete diagnosis, or to take in charge ambulatory the less severe cases all the more a reversible causes is identified. The situation often needs to take our time to avoid conceding too easily the definitive cardiac pacing. North American guidelines concerning cardiac pacing represent at least the references which we have to follow as often as possible particularly concerning atypical cases.

Incidence and type of cardiac arrhythmias in critically ill patients: a single center experience in a medical-cardiological ICU.

OBJECTIVE: To determine the frequency and types of significant, sustained arrhythmias in a mixed ICU. DESIGN AND SETTING: Prospective, observational study in a medical-cardiological-postoperative ICU at a university hospital. PATIENTS: 133 consecutive patients with arrhythmias. MEASUREMENTS AND RESULTS: All patients had continuous ECG monitoring and automatic arrhythmia detection. We assessed: (a) sustained (>30 s) tachyarrhythmias; (b) all tachyarrhythmias requiring therapy; (c) bradycardias of fewer than 40 beats/min or requiring intervention. There were 310 arrhythmia episodes: 278 tachyarrhythmias (108 narrow-QRS complex, 168 wide-QRS complex; 179 regular, 97 irregular) and 32 bradycardias. Of the 278 tachycardias in 54 patients, 135 (48.6%) were ventricular. There were 13 episodes of torsade de pointes (4.67%) in five patients. Of the 278 tachycardiac episodes 83 were atrial fibrillation (29.8%, 63 patients), 10 atrial flutter (3.6%, 8 patients), 21 supraventricular tachycardias (7.55%, 7 patients), and 2 ectopic junctional tachycardia (0.72%, 1 patient). The number of patients showing significant arrhythmias was comparable over the years (11-12/1996: 4/28 [14.3], 1997: 52/302 [17.2%], 1998: 55/286 [19.2%], 22/140 [15.7%] 1-7/1999). The ICU stay was significantly longer in arrhythmia patients than in 623 patients without arrhythmias (median 4 vs. 14 days), and there was a trend towards higher mortality (40/133, 30.8%, vs. 132/623, 21.2%, P=0.061, log-rank). CONCLUSION: Only one-fifth of patients in this mixed ICU had significant arrhythmias, taking a contemporary definition of arrhythmias. Ventricular tachycardia and atrial fibrillation were the most frequent arrhythmias.

Acute myocardial infarction complicated by hemodynamically unstable bradyarrhythmia: prehospital and ED treatment with atropine.

The purpose of this study was to investigate the therapeutic response to atropine of patients experiencing hemodynamically compromising bradyarrhythmia related to acute myocardial infarction (AMI) in the prehospital (PH) setting and the therapeutic impact of the PH response to atropine on further Emergency Department (ED) care. In addition, the prevalence of AMI in patients presenting with atrioventricular block (AVB) is noted. Retrospective review of PH, emergency department (ED), and hospital records. PH patients, with hemodynamically compromising bradycardia or AVB with evidence of spontaneous circulation, who received atropine as delivered by emergency medical services (EMS) personnel, were used. Urban/suburban fire department-based emergency medical services (EMS) system with on-line medical control serving a population of approximately 1.6 million persons. Hemodynamic instability was defined as the presence of any of the following: ischemic chest pain, dyspnea, syncope, altered mental status, and systolic blood pressure less than 90 mm Hg. Bradycardia was defined as sinus bradycardia, junctional bradycardia, or idioventricular bradycardia (grouped as bradycardia), whereas AVB included first-, second- (types I and II), or third-degree (grouped as AVB). The response that occurred within 1 minute of atropine dosing was recorded as none, partial, complete, or adverse. Comparisons were made between patients with AMI and non-AMI hospital discharge diagnoses. The diagnosis of AMI was confirmed by abnormal elevations in creatinine phosphokinase MB fraction. One hundred seventy-two patients meeting entry criteria were identified. Of these, 131 (76.1%) had complete PH, ED, and hospital records and were used for data analysis. Forty-five patients (34.3%) had a primary hospital discharge diagnosis of AMI; the remaining patients had a non-AMI discharge diagnosis. AMI patients were significantly younger (67 +/- 12 v 73 +/- 13 years, P = .025), were less likely to have a history of heart disease (35.5% v54.7%, P = .038), and were more likely to present with chest pain (68.9% v24.4%, P < .001) or hypotension (60% v37.2%, P = .013) compared with non-AMI patients. Forty-five of 131 patients presented with AVB, of which 25 had a hospital discharge diagnosis of AMI (55.6%). The mean time from first dose of atropine to ED arrival and the total dose of atropine received in the PH setting did not differ between AMI and non-AMI groups (15.2 +/- 7.7 v 16.2 +/- 8.7 minutes, P= .5; and 0.9 +/- 0.49 v 1.0 +/- 0.58 mg, P = .25). The likelihood of achieving normal sinus rhythm in the PH setting did not differ between AMI and non-AMI groups (40% v 18.6%, P = .07). No differences were found between AMI and non-AMI groups in the amount of additional atropine given (1.2 +/- 0.58 v 1.3 +/- 1.1 mg, P = .58) or the use of other resuscitative therapies after ED arrival (isoproterenol, 13.3% v12.8%, P = .93; dopamine, 28.9% v26.7% P = .79; transcutaneous pacing, 26.7% v26.7%, P = .99; transvenous pacing, 8.9% v5.8%, P = .51), with the exception of thrombolytic therapy (24.4% v 0%, P< .001) and cardiac catheterization (22.2% v3.4%, P = .001). Despite a lack of significant difference in achieving a normal sinus rhythm in the prehospital or ED setting, AMI patients were more likely to achieve a normal sinus rhythm over the total course of PH and ED care than non-AMI patients (44.4% v24.4%, P = .019). Hemodynamically unstable (by ACLS criterion) AVB presenting in the PH setting is associated with a hospital diagnosis of AMI in most (55.6%) patients in this study. AMI patients with hemodynamically unstable AVB or bradycardia are no more likely to respond to atropine therapy in the PH setting than patients with non-AMI hospital diagnoses. Finally, although there is no difference in the treatment of compromising AVB or bradycardia received by AMI versus non-AMI patients in the PH or ED setting, AMI patients are more likely to achieve a normal sinus rhythm over the t

Limitations of tachycardia confirmation and rate classification algorithms in a third-generation implantable cardioverter defibrillator.

Newer ICDs provide antitachycardia (ATP) and bradycardia pacing and cardioversion and defibrillation shocks based on sensed interval criteria. The objectives of this investigation were to determine the algorithm related errors in tachycardia confirmation and rate classification that occurred in patients with a third-generation, noncommitted, tiered ICD therapy. Forty-three consecutive patients with the Guardian ATP 4210 ICD, which uses an X out of Y sensed interval counting algorithm for tachycardia detection, confirmation, and classification were studied. Surface ECGs, intracardiac electrograms, stored data logs, and sense histories were reviewed to diagnose errors due to these algorithms that resulted in delivery of inappropriate therapy or inhibition of appropriate therapy. Sixty-eight classification or confirmation algorithm errors from 7,610 tachycardia detections (< 1%) were diagnosed in 23 (53%) of 43 patients. Three types of errors not related to device or sensing lead malfunction or programming mistakes were seen. In 26 episodes, the confirmation algorithm failed to detect late tachycardia reversion of nonsustained tachyarrhythmias, on the last or next to last sensed interval, and did not inhibit ATP (n = 17) or shocks (n = 9). In 28 episodes, inaccurate classification of tachycardia rate resulted in inappropriate ATP (n = 23) or shock (n = 5) therapy. In 14 episodes, the posttherapy reconformation algorithm produced inhibition of VVI pacing and prolonged asystole following shock therapy. These errors in tachycardia confirmation and rate classification were due to the inherent limitations of the X out of Y counting algorithm.

[Differential diagnosis and therapy of bradycardic arrhythmias]. / Differentialdiagnose und Therapie bradykarder Rhythmusstörungen.

The most important symptoms in bradycardia are vertigo, dizziness and syncopy due to diminished cerebral blood sypply. Cardial symptoms are cardiac insufficiency and angina pectoris. By means of ECG, especially Holter-ECG, carotid sinus massage, atropin test and invasive methods (atrial stimulation, His-bundle ECG) sinu-nodal dysfunction, carotid sinus syndrome, bradyarrhythmia absoluta and AV-block can be diagnosed. Pharmacological treatment is only useful in acute situations. For symptomatic bradyarrhythmias the implantation of a Pacemaker is the therapy of choice. Individual treatment of the various types of bradyarrhythmia and the patients special needs is possible through the evolution of pacemaker technology.

Bradiarritmias: abordagem clínica e tratamento / Bradiarrhythmias: clinical approach and treatment

Este artigo revisa a abordagem clínica das bradiarritmias, com ênfase no diagnóstico, ressaltando a importância da anamnese, exame físico e das alteraçöes eletrocardiográficas como principais orientadores da terapêutica

[Bradyarrhythmias (author's transl)]. / Bradykarde Rhythmusstörungen.

Bradyarrhythmias are due to disturbance of impulse formation and conduction in the heart. The sick sinus syndrome consists of both forms, sinusbradycardia being the most common type of arrhythmia, followed by sinus arrest and sinuatrial block. There is a wide range of the reported frequency of concomitant intermittent supraventricular tachycardia. Most patients have additional atrioventricular conduction disturbances. Diagnostic methods include measurement of the sinus node recovery time and sinoatrial conduction time, but therapy, i.e. pacemaker implantation depends largely on documentation of significant reduction of heart rate with clinical symptoms. The largest group of bradycardias is due to high degree atrioventricular block. As the prognosis of Mobitz Type II block is unfavorable in regard to development of complete distal av-block, differentiation between type I and II is of clinical importance, particularly in patients with additional fascicular block. Although exact localization of conduction disturbance with the Hisbundle-electrogram is possible, proof or exclusion of block distal to the Hisbundle including high frequency testing with atrial stimulation does not give the sole indication for therapeutic measures as follow up studies of patients with intraventricular conduction disturbances with and without distal block have demonstrated, that progression to complete av-block is difficult to predict.