Confounding factors leading to misdiagnosing ventricular tachycardia as supraventricular in the emergency room.

Studies conducted during the last 50 years have proposed electrocardiographic criteria and algorithms to determine if a wide QRS tachycardia is ventricular or supraventricular in origin. Sustained ventricular tachycardia is an uncommon reason for consultation in the emergency room. The latter and the complexity of available electrocardiographic diagnostic criteria and algorithms result in frequent misdiagnoses. Good hemodynamic tolerance of tachycardia in the supine position does not exclude its ventricular origin. Although rare, ventricular tachycardia in patients with and without structural heart disease may show a QRS duration <120 ms. Interruption of tachycardia by coughing, carotid sinus massage, Valsalva maneuver, or following the infusion of adenosine or verapamil should not discard the ventricular origin of the arrhythmia. In patients with regular, uniform, sustained broad QRS tachycardia, the presence of structural heart disease or A-V dissociation strongly suggest its ventricular origin. Occasionally, ventricular tachycardia can present with AV dissociation without this being evident on the 12-lead ECG. Cardiac auscultation, examination of the jugular venous pulse, and arterial pulse palpation provide additional clues for identifying A-V dissociation during tachycardia. This paper does not review the electrocardiographic criteria for categorizing tachycardia as ventricular but rather why emergency physicians misdiagnose these patients.

Acometimento do Ventrículo Direito na Cardiomiopatia por Depósito de Glicogênio (PRKAG2): Análise Ecocardiográfica Convencional e Avançada / Right Ventricle Involvement by Glycogen Storage Cardiomyopathy (PRKAG2): Standard and Advanced Echocardiography Analyses

Resumo Fundamento A síndrome do PRKAG2 é uma doença hereditária autossômica dominante rara, de início precoce. Objetivamos descrever os achados ecocardiográficos do ventrículo direito (VD) usando modalidades bi e tridimensionais (2D e 3D), incluindo índices de deformação miocárdica nesta cardiomiopatia. Também objetivamos demonstrar se esta técnica poderia identificar alterações na função do VD que pudessem distinguir quaisquer achados particulares. Métodos Trinta pacientes com síndrome do PRKAG2 (R302Q e H401Q) geneticamente comprovada, 16 (53,3%) do sexo masculino, com idade média de 39,1 ± 15,4 anos, foram submetidos a exame ecocardiográfico completo. A visão de 4 câmaras com foco no VD foi adquirida para medições 2D e 3D. Os testes t de Student ou Wilcoxon-Mann-Whitney foram usados para comparar as variáveis numéricas entre 2 grupos, e p < 0,05 foi considerado significativo. Resultados Doze pacientes (40%) tiveram marca-passo implantado por 12,4 ± 9,9 anos. A espessura diastólica média da parede livre do VD foi de 7,9 ± 2,9 mm. O strain longitudinal de 4 câmaras do VD (SL4VD), incluindo a parede livre e o septo interventricular, foi de -17,3% ± 6,7%, e o strain longitudinal da parede livre do VD (SLPLVD) foi de −19,1% ± 8,5%. A razão apical do SLPLVD mediu 0,63 ± 0,15. A fração de ejeção (FE) 3D média do VD foi de 42,6% ± 10,9% e abaixo dos limites normais em 56,7% dos pacientes. Correlação positiva ocorreu entre FE 3D do VD, SL4VD e SLPLVD, principalmente para pacientes sem marca-passo (p = 0,006). Conclusão O envolvimento do VD em PRKAG2 é frequente e ocorre em diferentes graus. A ecocardiografia é uma ferramenta valiosa na detecção de anormalidades miocárdicas do VD nesta condição. O uso de SL4VD 2D, SLPLVD e FE 3D oferecem indicadores confiáveis de disfunção sistólica do VD nesta cardiomiopatia rara e desafiadora.

Abstract Background PRKAG2 syndrome is a rare, early-onset autosomal dominant inherited disease. We aimed to describe the right ventricle (RV) echocardiographic findings using two and three-dimensional (2D and 3D) modalities including myocardial deformation indices in this cardiomyopathy. We also aimed to demonstrate whether this technique could identify changes in RV function that could distinguish any particular findings. Methods Thirty patients with genetically proven PRKAG2 (R302Q and H401Q), 16 (53.3%) males, mean age 39.1 ± 15.4 years, underwent complete echocardiography examination. RV-focused, 4-chamber view was acquired for 2D and 3D measurements. Student's t or Wilcoxon-Mann-Whitney tests were used to compare numerical variables between 2 groups, and p < 0.05 was considered significant. Results Twelve patients (40%) had a pacemaker implanted for 12.4 ± 9.9 years. RV free wall mean diastolic thickness was 7.9 ± 2.9 mm. RV 4-chamber longitudinal strain (RV4LS), including the free wall and interventricular septum, was -17.3% ± 6.7%, and RV free wall longitudinal strain (RVFWLS) was −19.1% ± 8.5%. The RVFWLS apical ratio measured 0.63 ± 0.15. Mean RV 3D ejection fraction (EF) was 42.6% ± 10.9% and below normal limits in 56.7% of patients. Positive correlation occurred between RV 3DEF, RV4LS, and RVFWLS, especially for patients without a pacemaker (p = 0.006). Conclusion RV involvement in PRKAG2 syndrome is frequent, occurring in different degrees. Echocardiography is a valuable tool in detecting RV myocardial abnormalities in this condition. The use of 2D RV4LS, RVFWLS, and 3DEF offers reliable indicators of RV systolic dysfunction in this rare, challenging cardiomyopathy.

Atrial Fibrillation and Use of Rivaroxaban: Performance of the Prothrombin Time / INR as a Function of Time After Blood Collection

Abstract Background Traditionally, the most effective therapy in the prevention of stroke in patients with atrial fibrillation (AF) has been oral anticoagulation with vitamin K inhibitors, particularly warfarin, whose disadvantages and adverse effects have led to their replacement by "direct oral anticoagulants", as factor X inhibitor. Objectives This study aimed to conduct a brief approach on atrial fibrillation (AF) and use of Rivaroxaban, and to comparatively evaluate the prothrombin time / International Normalized Ratio (PT/INR) in patients with AF in use of this oral anticoagulant, depending on the time elapsed between the last administration of the drug and the time of blood sample venipuncture. Methods We evaluated 34 patients with AF in use of Rivaroxaban by using PT / INR, distributed into a subgroup with blood collection time ≤ 12 hours (n = 7) and > 12 hours after the last drug intake (n = 27). Mann-Whitney test was used to compare the groups and p < 0.05 was considered significant. Results An analysis as a function of time between the Rivaroxaban intake and blood collection, revealed that PT / INR suffers the greatest effect up to 12 hours after ingestion of the drug, dropping to levels close to normal in subsequent hours before the next dose. Conclusion We concluded that, in contrast to warfarin, the knowledge of the time interval between drug intake and blood collection from patients taking Rivaroxaban is essential to properly interpret a laboratory test to assess hemostasis, particularly PT and its derivatives. Int J Cardiovasc Sci. 2020; [online].ahead print, PP.0-0

Atypical bypass tracts: can they be recognized during sinus rhythm?

Atypical bypass tracts or variants of ventricular pre-excitation are rare anatomic structures often with rate-dependent slowing in conduction, called decremental conduction. During sinus rhythm, electrocardiographic recognition of those structures may be difficult because unlike in the Wolff-Parkinson-White syndrome where usually overt ventricular pre-excitation is present, the electrocardiogram (ECG) often shows a subtle pre-excitation pattern because of less contribution to ventricular activation over the slow and decrementally conducting bypass. Following the structure described by Ivan Mahaim and Benatt corresponding to a fasciculoventricular pathway, several other new variants of ventricular pre-excitation were reported. In this review, we aim to discuss the electrocardiographic pattern of the different subtypes of variants of ventricular pre-excitation, including the atriofascicular pathway, long and short decrementally conducting atrioventricular pathways, fasciculoventricular pathway, the atrio-Hisian bypass tract, and nodoventricular and nodofascicular fibres. Emphasis will be on the ECG findings during sinus rhythm.

Cryptogenic Acute Ischemic Stroke: Assessment of the Performance of a New Continuous Long-Term Monitoring System in the Detection of Atrial Fibrillation / AVC Isquêmico Agudo Criptogênico: Avaliação do Desempenho de um Novo Sistema de Monitorização Contínua e Prolongada, via Telefonia Celular, na Detecção de Fibrilação Atrial

Abstract Background: Long-term monitoring has been advocated to enhance the detection of atrial fibrillation (AF) in patients with stroke. Objective: To evaluate the performance of a new ambulatory monitoring system with mobile data transmission (PoIP) compared with 24-hour Holter. We also aimed to evaluate the incidence of arrhythmias in patients with and without stroke or transient ischemic attack. Methods: Consecutive patients with and without stroke or TIA, without AF, were matched by propensity score. Participants underwent 24-hour Holter and 7-day PoIP monitoring. Results: We selected 52 of 84 patients (26 with stroke or TIA and 26 controls). Connection and recording times were 156.5 ± 22.5 and 148.8 ± 20.8 hours, with a signal loss of 6,8% and 11,4%, respectively. Connection time was longer in ambulatory (164.3 ± 15.8 h) than in hospitalized patients (148.8 ± 25.6 h) (p = 0.02), while recording time did not differ between them (153.7 ± 16.9 and 143.0 ± 23.3 h). AF episodes were detected in 1 patient with stroke by Holter, and in 7 individuals (1 control and 6 strokes) by PoIP. There was no difference in the incidence of arrhythmias between the groups. Conclusions: Holter and PoIP performed equally well in the first 24 hours. Data transmission loss (4.5%) occurred by a mismatch between signal transmission (2.5G) and signal reception (3G) protocols in cell phone towers (3G). The incidence of arrhythmias was not different between stroke/TIA and control groups.

Resumo Fundamentos: Monitorização prolongada permite maior detecção de fibrilação atrial (FA) em pacientes com acidente vascular cerebral (AVC) isquêmico criptogênico. Não há consenso sobre a duração ideal da monitorização ou o valor prognóstico da FA de curta duração. Objetivos: Avaliar o desempenho de um novo sistema de monitorização ambulatorial (PoIP) com transmissão por telefonia celular, comparado ao Holter 24 horas, e a ocorrência de arritmias comparando pacientes com e sem AVC ou ataque isquêmico transitório (AIT). Métodos: Pacientes consecutivos com e sem AVC/AIT, sem FA, foram pareados pelo escore de propensão. Foi utilizado Holter 24 horas e o PoIP por 7 dias. Resultados: Selecionamos 52 de 84 pacientes (26 com AVC/AIT agudo e 26 controles). O tempo de conexão foi de 156,5 ± 22,5 horas e o de gravação no servidor foi de 148,8 ± 20,8 horas, com perdas de 6,8 e 11,4%, respectivamente. Houve maior tempo de conexão nos pacientes ambulatoriais (164,3 ± 15,8 h) que nos hospitalizados (148,8 ± 25,6h) (p = 0,02) com tempo de gravação semelhante (153,7 ± 16,9 e 143 ± 23,3 h). Detectamos FA pelo Holter em 1 paciente com AVC e pela monitorização prolongada em 7 (1 controle e 6 AVC). Não houve diferença na incidência de outras arritmias entre os grupos. Conclusões: Holter e PoIP tiveram desempenho equivalente nas primeiras 24 horas. O menor tempo de monitorização nos pacientes hospitalizados ocorreu por sinal de baixa intensidade. Perda de dados (4,5%) ocorreu por discrepância entre protocolos de transmissão (2,5G) e recepção pelas antenas (3G). A incidência de arritmias não diferiu entre os grupos AVC/AIT e controle.

Fatores associados à mediastinite pós-esternotomia, caso-controle / Factors associated with post-mediastinitis. Case-control study

Fundamentos: A mediastinite é uma infecção grave pós-esternotomia mediana com prognóstico ruim, mesmo com diagnóstico e tratamento precoces. Objetivos: Avaliar o perfil dos pacientes submetidos à esternotomia, identificar fatores de risco para o desenvolvimento da mediastinite e avaliar o diagnóstico bacteriológico dos pacientes com esta infecção. Métodos: Estudo caso-controle realizado em um hospital de Belo Horizonte (MG) com pacientes submetidos à esternotomia mediana entre janeiro de 2015 e janeiro de 2016. A amostra foi de 65 pacientes, sendo 13 casos e 52 controles (1:4). Na análise estatística, foram adotados os testes t de Student, Mann-Whitney e exato de Fisher, além de regressão logística, ao nível de significância de 5%. Resultados: Houve predominância do sexo masculino (63,1%), e a idade média foi 58,8 ±10,3 anos. A evolução a óbito ocorreu em 9,2% dos pacientes e em 23,1% dos que apresentaram mediastinite. A cirurgia de revascularização do miocárdio foi realizada em 75,4% dos casos. Predominância do sexo masculino, maior tempo de internação, febre pós-cirúrgica, óbitos e maior número de fatores de risco foram características mais observadas nos pacientes que desenvolveram mediastinite. O microrganismo mais encontrado em pacientes com infecção mediastinal foi Staphylococcus aureus (30,7%), além de elevada ocorrência de bactérias Gram-negativas (46,2%). Conclusão: Esforços devem ser concentrados para o controle dos fatores de risco antes do procedimento, além do aprimoramento de medidas que possam diminuir ou eliminar o surgimento da mediastinite, visando à prevenção e ao melhor controle de infecções

Background: Mediastinitis is a severe post-median sternotomy infection with poor prognosis, even with early diagnosis and treatment. Objectives: To evaluate the profile of patients submitted to sternotomy, identify the risk factors for the development of mediastinitis and evaluate the bacteriological diagnosis of patients with this infection. Methods: Case-control study carried out in a large hospital in Belo Horizonte (MG, Brazil) in patients submitted to median sternotomy, from January 2015 to January 2018. The sample consisted of 65 patients, of which 13 were cases and 52, controls (1:4). For the statistical analysis, Student's t test, Mann-Whitney test and Fisher exact test were used, in addition to logistic regression, with a level of significance of 5%. Results: There was a predominance of males (63.1%), and the mean age was 58.8 ± 10.3 years. Evolution to death occurred in 9.2% of the patients and in 23.1% of those with mediastinitis. Myocardial revascularization was performed in 75.4% of the cases. Predominance of male gender, longer hospitalization time, post-surgical fever and death, and a greater number of risk factors were more frequent characteristics in patients who developed mediastinitis. The most common microorganism found in patients with mediastinal infection was Staphylococcus aureus (30.7%), in addition to a high occurrence of Gram-negative bacteria (46,2%). Conclusion: The results are in accordance with the literature. Efforts should be focused on the control of risk factors prior to the procedure, in addition to improving measures that can decrease or eliminate the onset of mediastinitis, aiming at infection prevention and control

Reappraisal and new observations on atrial tachycardia ablated from the non-coronary aortic sinus of Valsalva.

Aims: The clinical characteristics of atrial tachycardias (AT) ablated from the non-coronary aortic sinus (NCS) are thus far described only in small series. We aimed to outline, in a large cohort of patients, the clinical, electrocardiographic, electrophysiological characteristics of this tachycardia. Methods and results: We analysed data pertaining to clinical, electrocardiographic, and electrophysiological characteristics of 43 consecutive patients from an overall cohort of 441 with AT who were successfully ablated from the NCS. The tachycardias ablated from the NCS were paroxysmal (98%) and adenosine sensitive (35/35). The patients were aged 54.6 ± 12.4 years, showing female preponderance (74%). No P wave pattern was predictive of the location of ablation. Electrophysiological findings suggested a possible micro-reentrant mechanism. During tachycardia, atrial electrograms recorded in the NCS preceded the A in the His region by 10.9 ± 7.4 ms. Fractionated atrial electrograms were noted at the site of ablation in 42 patients during the tachycardia. Radiofrequency ablation terminated the tachycardia within 5 s in 88%, with thermal automaticity seen only in 3 patients. The site of ablation at the base of the NCS was adjacent to the presumed site of the retroaortic node, a remnant of the initial atrio-ventricular canal musculature. Conclusions: AT ablated from the NCS is a paroxysmal arrhythmia in middle-aged women, with distinct electrocardiographic and electrophysiological characteristics. We suspect the retroaortic node to be involved in the tachycardia circuit.

Percutaneous Catheter Ablation of Epicardial Accessory Pathways.

Radiofrequency (RF) catheter ablation is the treatment of choice in patients with accessory pathways (APs) and Wolff-Parkinson-White syndrome. Endocardial catheter ablation has limitations, including the inability to map and ablate intramural or subepicardial APs. Some of these difficulties can be overcome using an epicardial approach performed through the epicardial venous system or by percutaneous catheterisation of the pericardial space. When a suspected left inferior or infero-paraseptal AP is refractory to ablation or no early activation is found at the endocardium, a transvenous approach via the coronary sinus is warranted because such epicardial pathways can be in close proximity to the coronary venous system. Associated congenital abnormalities, such as right atrial appendage, right ventricle diverticulum, coronary sinus diverticulum and absence of coronary sinus ostium, may also hamper a successful outcome. Percutaneous epicardial subxiphoid approach should be considered when endocardial or transvenous mapping and ablation fails. Epicardial mapping may be successful. It can guide and enhance the effectiveness of endocardial ablation. The finding of no epicardial early activation leads to a more persistent new endocardial attempt. When both endocardial and epicardial ablation are unsuccessful, open-chest surgery is the only option to eliminate the AP.

Custos e Desfechos Clínicos na Intervenção Coronária Percutânea no Sistema Único de Saúde / Costs and Clinical Outcomes in Percutaneous Coronary Intervention by the Brazilian National Health System

O tratamento percutâneo da doença arterial coronariana (DAC) pode apresentar desfechos adversos relacionados às características da população e questões técnicas. DAC é uma das principais fontes de gastos com internações no SUS, especificamente o tratamento das síndromes coronarianas agudas (SCA), associado, principalmente, a procedimentos intervencionistas. Objetivos: Avaliar a efetividade e custo do tratamento de revascularização miocárdica percutânea realizado pelo SUS em hospital terciário em Minas Gerais. Métodos: Realizou-se uma coorte aberta prospectiva, com indivíduos submetidos à angioplastia coronária, pelo SUS, entre setembro/14 e abril/15. Os pacientes foram classificados conforme características clínicas e angiográficas e caráter do procedimento. Realizou-se acompanhamento por seis meses e avaliou-se a efetividade do tratamento. Foram levantados os gastos do SUS com os pacientes que realizaram os procedimentos eletivamente ou de urgência. Compararam-se os custos hospitalares com os valores pagos pelo SUS. Resultados: Em 83,2% dos 101 pacientes, o procedimento foi de urgência. Foram observados em seis meses: óbito (10,9%), reestenose clínica (7,9%) e infarto não fatal (2%). Não foram verificadas diferenças, com relação aos desfechos, entre os grupos angiográficos, clínicos e caráter do procedimento. Os valores pagos pelo SUS para tratamentos eletivos foram menores que os de urgência, com diferença do gasto mediano de R$1.768,75. Comparando-se os valores pagos pelo SUS aos custos da instituição, o déficit foi de R$ 430.095,30, com diferença mediana de R$ 2.283,74. Conclusões: O tratamento de revascularização miocárdica percutânea, pelo SUS, é efetivo. Os custos são maiores na urgência, e os valores pagos pelo SUS são deficitários. (Int J Cardiovasc Sci. 2016;29(6):431-442) Palavras-chave: Intervenção Coronária Percutânea / economia; Sistema Único de Saúde (SUS) / economia; Doença da Arterial Coronariana; Avaliação de Resultado de Intervenções Terapêuticas; Custos Hospitalares

Percutaneous treatment of coronary arterial disease (CAD) can present adverse outcomes related to population characteristics and technical issues. CAD is one of the main sources of expense, with admission in the Brazilian Unified Health System (SUS), more specifically with treatments for acute coronary syndromes (ACS), mainly associated to interventional procedures. Objectives: To evaluate the effectiveness and cost of percutaneous myocardial revascularization performed through SUS at a tertiary hospital in the Brazilian State of Minas Gerais. Methods: We used a prospective open cohort, with individuals who underwent coronary angioplasty, through SUS, between September 2014 and April 2015. The patients were classified according to clinical and angiographic characteristic and character of the procedure. A six-month follow up was carried out and we evaluated treatment effectiveness. We verified the health system's expenditures with patients who underwent the procedure electively or as emergency surgery. We compared hospital costs with the amounts paid by SUS. Results: Of the 101 patients, 83.2% of cases underwent the procedure as emergency surgery. In six months, we observed: death (10.9%), clinical restenosis (7.9%), and non-fatal infarction (2%). No differences were observed, regarding the outcomes, between angiographic, clinical groups and character of the procedure. Amounts paid by SUS for elective treatments were smaller than emergency ones, with a median difference in expenditure of R$ 1,768.75. When comparing the amounts paid by SUS to institution costs, the deficit was of R$ 430,095.30, with a median difference of R$ 2,283.74. Conclusions: Percutaneous myocardial revascularization treatment is effective through SUS. Costs are higher in emergency scenarios, and the amounts paid by SUS are deficient.

Chronic Activation of γ2 AMPK Induces Obesity and Reduces ß Cell Function.

Despite significant advances in our understanding of the biology determining systemic energy homeostasis, the treatment of obesity remains a medical challenge. Activation of AMP-activated protein kinase (AMPK) has been proposed as an attractive strategy for the treatment of obesity and its complications. AMPK is a conserved, ubiquitously expressed, heterotrimeric serine/threonine kinase whose short-term activation has multiple beneficial metabolic effects. Whether these translate into long-term benefits for obesity and its complications is unknown. Here, we observe that mice with chronic AMPK activation, resulting from mutation of the AMPK γ2 subunit, exhibit ghrelin signaling-dependent hyperphagia, obesity, and impaired pancreatic islet insulin secretion. Humans bearing the homologous mutation manifest a congruent phenotype. Our studies highlight that long-term AMPK activation throughout all tissues can have adverse metabolic consequences, with implications for pharmacological strategies seeking to chronically activate AMPK systemically to treat metabolic disease.

Accessory atrioventricular pathways refractory to catheter ablation: role of percutaneous epicardial approach.

BACKGROUND: Epicardial mapping and ablation of accessory pathways through a subxiphoid approach can be an alternative when endocardial or epicardial transvenous mapping has failed. METHODS AND RESULTS: We reviewed acute and long-term follow-up of 21 patients (14 males) referred for percutaneous epicardial accessory pathway ablation. There was a median of 2 previous failed procedures. All patients were highly symptomatic, 8 had atrial fibrillation (3 with cardiac arrest) and 13 had frequent symptomatic episodes of atrioventricular reentrant tachycardia. Six patients (28.5%) had a successful epicardial ablation. Five patients (23.8%) underwent a successful repeated endocardial mapping, and ablation after epicardial mapping yielded no early activation site. Epicardial mapping was helpful in guiding endocardial ablation in 2 patients (9.5%), showing that the earliest activation was simultaneous at the epicardium and endocardium. Four patients (19%) underwent successful open-chest surgery after failing epicardial/endocardial ablation. Two patients (9.5%) remained controlled under antiarrhythmic drugs after unsuccessful endocardial/epicardial ablation. Two patients had a coronary sinus diverticulum and one a right atrium to right ventricle diverticulum. Three patients acquired postablation coronary sinus stenosis. There was no major complication related to pericardial access. CONCLUSIONS: Percutaneous epicardial approach is an alternative when conventional endocardial or transvenous epicardial ablation fails in the elimination of the accessory pathway. A new attempt by endocardial approach was successful in a significant number of patients. Open-chest surgery may be required in symptomatic cases refractory to endocardial-epicardial approach.

Postablation-acquired short atrioventricular Mahaim-type fibers: observations on their clinical, electrocardiographic, and electrophysiologic profile.

BACKGROUND: The electrophysiologic characteristics of decrementally conducting accessory pathways (APs) are well described; however, little is known about decrementally conducting APs caused by the radiofrequency ablation of a rapidly conducting AP. OBJECTIVE: To report the clinical, electrocardiographic, and electrophysiologic characteristics of 6 patients who developed a decremental AP after an attempt at ablation. METHODS: We compared the clinical and electrophysiologic characteristics of 295 consecutive patients with the Wolff-Parkinson-White syndrome who underwent radiofrequency ablation of 311 manifest APs (group A) with those of 6 patients with the Wolff-Parkinson-White syndrome in whom a decrementally conducting AP was detected after an attempt at ablation. RESULTS: The AP ablation site in group B patients was at the coronary sinus ostium region in 3 patients, middle cardiac vein in 2 patients, and left posteroseptal region in 1 patient. Sixty-two bypass tracts in group A patients and all 6 in group B patients were ablated at these locations, while 249 bypass tracts in group A patients and none in group B patients were ablated elsewhere (P = .0001). Five of the 6 patients (83%) with acquired Mahaim physiology had an AP located in the venous system. The odds for developing an acquired decremental antegrade atrioventricular AP when it was located inside the venous system were 1 in 6. All group B decremental APs were sensitive to adenosine, but none in 85 group A patients (P <.0001). CONCLUSIONS: The risk for developing decremental conduction after the ablation of a rapidly conducting AP is greater for APs inside the coronary venous system. Acquired decremental antegrade atrioventricular APs are electrophysiologically similar to de novo ones. They are capable of being part of an arrhythmia circuit and, therefore, should be targeted for ablation.

Short atrioventricular Mahaim fibers: observations on their clinical, electrocardiographic, and electrophysiologic profile.

UNLABELLED: Short A-V manheim fiber. INTRODUCTION: A short atrioventricular decrementally conducting accessory pathway is an uncommon variant of preexcitation. Available data from small series suggest that their decremental properties might not be caused by A-V nodal-like tissue. METHODS: We compared clinical, electrocardiographic and electrophysiologic parameters in two groups of patients: 8 patients with a short A-V Mahaim pathway (Group A), and 33 patients with atriofascicular pathways (Group B). Radiofrequency catheter ablation was carried out guided by activation mapping at the annulus in Group A patients and targeting the "M" potential in Group B patients. RESULTS: After ablation of all associated rapidly conducting bypass tracts, 7 of the 8 Group A patients showed clear preexcitation. In only 1 of 8 patients the short A-V Mahaim fiber was actively engaged in a reentrant tachycardia circuit. During radiofrequency catheter ablation an automatic rhythm occurred in 4 of 8 patients. Intravenous adenosine caused conduction a block in the Mahaim fiber in 3 of the 5 patients tested. In group B, no patient showed clear preexcitation (P<00001) while 72% had a minimal preexcitation pattern. Twenty-nine of the 33 patients had a circus movement tachycardia with AV conduction over the atriofascicular fiber. During radiofrequency catheter ablation 30 of 33 patients showed accessory pathway automaticity. Adenosine caused transient block at the atriofascicular pathway in 11 (92%) of the 12 patients tested. CONCLUSIONS: While short decrementally conducting right-sided accessory pathways show a typical ECG pattern different from atriofascicular pathways, their electrophysiologic properties do not seem to be uniform. Those pathways can be successfully interrupted by catheter ablation.

Fasciculoventricular pathways: clinical and electrophysiologic characteristics of a variant of preexcitation.

UNLABELLED: Fasciculoventricular Fibers. INTRODUCTION: Fasciculoventricular tracts are considered a rare form of ventricular preexcitation. Few fasciculoventricular pathways have been reported, and none have been linked to a reentrant tachycardia. METHODS AND RESULTS: Four patients with fasciculoventricular bypass tracts underwent electrophysiologic evaluation. Two patients had a single fasciculoventricular pathway, one that inserted anteroseptally and the other in the left ventricle. Two patients also had an AV bypass tract, with anterograde conduction over the fasciculoventricular pathway during orthodromic AV reentrant tachycardia. After ablation of the AV pathways, the ECG during sinus rhythm and the electrophysiologic study showed ventricular preexcitation due to a fasciculoventricular bypass tract inserting into the right ventricle. Adenosine triphosphate was helpful in the diagnostic process. CONCLUSION: Electrophysiologists should be able to make the differential diagnosis between a fasciculoventricular bypass tract and an anteroseptal accessory pathway to preclude potential harm to the AV conduction system if a fasciculoventricular pathway is targeted for catheter ablation.

Ablaçäo por cateter com radiofrequência em vias acessórias esquerdsa: abordagem transaórtica versus transseptal / Radiofrequency catheter ablation of left sided accessory pathways: comparison between transeptal and transaortic approach

O objetivo deste estudo foi comparar a eficácia e a segurança das técnicas retroaórtica (n=25) e transseptal, utilizadas na ablaçäo por cateter com radiofreqüência de vias acessórias esquerdas em 55 pacientes. A abordagem transseptal incluiu 4 pacientes com forame oval patente e 31 submetidos a punçäo do septo interatrial pela técnica de Brockenbrough. Na presença de foame oval permeável a abordagem transseptal era a de eleiçäo. Na sua ausência, os pacientes foram aleatoriamente submetidos a uma ou outra técnica. A exceçäo foram os pacientes com menos de 16 anos (n=12), quando a preferência recaiu sobre a transseptal, com intuito de ablacionar a inserçäo atrial da via anômala (10/12). Em 28 pacientes adotou-se primariamente a via transseptal, além de outros 7 casos onde esta via de acesso foi utilizada numa segunda sessäo (6 pacientes com falha e 1 pacientes com recorrência, previamente submetidos a uma sessäo inicial com acesso retraórtica proporcionou 73 "por cento" de sucesso (19/25 pacientes), enquanto que a via transseptal obeteve 92 "por cento" de sucesso (32/35)(P=0,2). O índice de eficácia global foi de 93 "por cento" (51/55) pacientes). Para ambas as técnicas, näo houve diferença significativa (análise univariável) entre o número de aplicaçöes de radiofreqüência, o tempo total do procedimento e o intervalo delta-V nos casos com Wolff-Parkinson-White (WPW)...