Introdução: A fibrilação atrial (FA) é a arritmia cardíaca mais prevalente e aumenta em 5 vezes o risco de acidentes vasculares cerebrais (AVC). Sua prevalência aumenta à medida que envelhecemos e estima-se que entre os indivíduos com mais de 80 anos, pelo menos 10% seja portador de FA. Os infartos cerebrais entre os pacientes fibrilados tendem a ser mais extensos, provocando sequelas mais graves e também são caracterizados por maior mortalidade. A anticoagulação com antagonistas da vitamina K ou dos novos anticoagulantes orais reduz de forma significativa a incidência e a gravidade destes eventos vasculares e é recomendada a todos os pacientes portadores de um ou mais fatores de risco para AVC. Apesar destas recomendações, muitos pacientes ainda deixam de ser anticoagulados, especialmente os mais idosos. Estima-se que metade dos pacientes com indicação de anticoagulação não esteja recebendo tratamento. Objetivos: O objetivo principal foi avaliar a prevalência de anticoagulação oral nos pacientes fibrilados com fatores de risco para AVC em um centro terciário. Os objetivos secundários foram examinar as opções de tratamento escolhidas, verificar quais fatores podem estar associados à não prescrição de anticoagulação nestes pacientes e quais podem estar relacionados à maior ou menor eficácia da anticoagulação com antagonistas de vitamina K. Resultados: Foram avaliados 145 pacientes portadores de fibrilação atrial dos Ambulatórios de Medicina Interna e Geriatria do Hospital de Clínicas de Porto Alegre através da revisão dos prontuários e da aplicação de questionários por telefone. A prevalência de anticoagulação foi de 78%. Não houve diferenças entre anticoagulados e não anticoagulados em relação às variáveis estudadas. Foi constatada associação entre maior grau de dependência e eficácia da anticoagulação (p=0,04). Conclusão: A prevalência de prescrição de anticoagulação oral neste grupo de pacientes está acima da média descrita na literatura. Não houve diferença significativa entre pacientes anticoagulados e não anticoagulados em relação às demais variáveis estudadas. Foi constatada uma maior eficácia na anticoagulação oral dos pacientes mais dependentes, possivelmente relacionada ao controle da anticoagulação por terceiros. / Introduction: Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia and increases the risk of stroke by 5 times. Its prevalence increases as we age and it is estimated that among individuals older than 80 years, at least 10% have AF. Cerebral infarctions among fibrillated patients tend to be more extensive, causing more severe sequelae and are characterized by increased mortality. Anticoagulation with vitamin K antagonists or new oral anticoagulants significantly reduces the incidence and severity of these vascular events and is recommended for all patients with one or more risk factors for stroke. Despite these recommendations, many patients are still no longer anticoagulated, especially the elderly. It is estimated that half of the patients with indication for anticoagulation are not receiving treatment. Objectives: The main objective was to evaluate the prevalence of oral anticoagulation in fibrillated patients with risk factors for stroke in a tertiary center. The secondary objectives were to examine the treatment options chosen, to verify which factors may be associated with the non-prescription of anticoagulation in these patients and which may be related to the greater or lesser efficacy of anticoagulation with vitamin K antagonists. Results: 145 patients with atrial fibrillation of the Ambulatory of Internal Medicine and Geriatrics of the Hospital de Clínicas de Porto Alegre were evaluated through the revision of the medical records and the application of telephone questionnaires. The prevalence of anticoagulation was 78%. There were no differences between anticoagulated and non-anticoagulated patients in relation to the studied variables. An association between greater degree of dependence and efficacy of anticoagulation was observed (p = 0.04). Conclusion: The prevalence of oral anticoagulation prescription in this group of patients is higher than described in the literature. There was no significant difference between anticoagulated and non-anticoagulated patients in relation to the other variables studied. It was observed a greater efficacy in the oral anticoagulation of the more dependent patients, possibly related to the control of the anticoagulation by third parties.

Publicación a texto completo no autorizada por el autor / Determina la relación entre la prescripción de terapia antitrombótica y el riesgo embólico en pacientes con fibrilación auricular no valvular atendidos en el Hospital Luis Negreiros Vega de enero del 2011 a junio del 2013. El estudio es tipo transversal, analítico y retrospectivo. Se realizó en pacientes con fibrilación auricular no valvular. Se recogieron los datos de las historias clínicas electrónicas. Se utilizó porcentajes, promedios y desviación estándar. Se usó la prueba Chi cuadrado y la regresión logística binaria. Se utilizó las escalas CHADS2, CHA2DS2-VASc. Resultados: Se incluyeron 354 registros. Según la escala CHADS2 el 8,7%; 19,8%; y 71,5% correspondieron a riesgo embólico bajo, intermedio y alto. Según la escala CHA2DS2-VASc el 3,1%; 9%; y 87,9% correspondieron a riesgo embólico bajo intermedio y alto respectivamente. Según CHA2DS2-VASc recibieron antiagregación 9,1%; 28,1%; y 35,7% de los pacientes en riesgo bajo, intermedio y alto respectivamente; recibieron anticoagulación 34,4% y 46,9%en riesgo intermedio y alto respectivamente; y en riesgo alto 5,5% recibieron ambos. El tratamiento antitrombótico se relacionó con el riesgo embólico estimado por CHADS2 y CHA2DS2-VASc (ambos p<0,001). En el análisis multivariado en pacientes con riesgo alto según CHA2DS2-VASc se asociaron a la prescripción de anticoagulación: hipertensión arterial (OR 2,51; IC 95% 1,21-5,22; p=0,014), fibrilación auricular persistente (OR 6,55; IC 95% 3,11-13,76; p<0,001) y permanente (OR 13,63; IC 95% 6,90-26,94; p<0,001). La prescripción de terapia antitrombótica tuvo relación con el riesgo embólico estimado aunque la proporción de pacientes con tratamiento fue menor al requerido. / Tesis

Atrial Fibrillation (AF) is a debilitating heart rhythm disorder affecting over 2.7 million people in the US and over 30 million people worldwide annually. It has a high correlation with causing a stroke and several other risk factors, resulting in increased mortality and morbidity rate. Currently, the non-pharmocological therapy followed to control AF is catheter ablation, in which the tissue surrounding the pulmonary veins (PVs) is cauterized (called the PV isolation - PVI procedure) aims to block the ectopic triggers originating from the PVs from entering the atrium. However, the success rate of PVI with or without other anatomy-based lesions is only 50%-60%. A major reason for the suboptimal success rate is the failure to eliminate patientspecific non-PV sources present in the left atrium (LA), namely reentry source (a.k.a. rotor source) and focal source (a.k.a. point source). It has been shown from several animal and human studies that locating and ablating these sources significantly improves the long-term success rate of the ablation procedure. However, current technologies to locate these sources posses limitations with resolution, additional/special hardware requirements, etc. In this dissertation, the goal is to develop an efficient algorithm to locate AF reentry and focal sources using electrograms recorded from a conventionally used high-resolution multi-pole diagnostic catheter. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Background: We reviewed our experience using the Amplatzer septal occluder (AGA Medical, Golden Valley, MN) to close large, secundum-type atrial septal defects (ASDs) in children. Methods: Between June 2002 and December 2005, 52 patients (mean age 13.5 ¡Ó 8.7 years) underwent transcatheter closure of large (≥25 mm), secundum ASDs by using the Amplatzer septal occluder (ASO). Groups 1 and 2 included patients with a retroaortic rim of <5 mm (n = 39) or ≥5 mm(n = 13), respectively. All procedures were performed with general anesthesia and transesophageal echocardiographic guidance except for 10 patients, which involved local anesthesia and 3-dimensional transthoracic echocardiography. Successful device implantations, device sizes, approaches, complications, and closure rates were assessed. Results: Device implantation was successful in 50 patients (96.1%), with no difference between groups (95% vs 100%, P > 0.05). In 2 patients, implantation failed because of embolism or deployment failure. Devices were larger in group 1 than in group 2 (29.7 ¡Ó 3.9 vs 26.7 ¡Ó 3.0 mm, P =0.04). The right upper pulmonary-vein approach was more common in group 1 than in group 2 (P = .0001). Complications and closure rates did not differ between the groups (P > .05). Conclusions: Transcatheter closure of large, secundum ASD by using the ASO device was feasible, and complication rates were low. A deficient retroaortic rim did not preclude successful device implantation; however, a large device may be needed to close large ASD. Close long-term follow-up is necessary to determine the safety of transcatheter closure of large ASDs in children.

Atrial arrhythmias are very common clinically relevant conditions that are strongly associated with aging and parasympathetic tone. Additionally, ATP-sensitive K+ (KATP) channel activation has been reported to facilitate the development of re-entrant atrial arrhythmias. Since KATP channels are direct effectors of Gαi/o and RGS4 is an inhibitor of Gαi/o-signaling, we here investigate whether KATP channel activity is increased under decreased RGS4 activity in a manner that enhances susceptibility to AF. We show that loss of RGS4 facilitates the induction of atrial arrhythmias under parasympathetic challenge both in whole animals and isolated atrial tissues. Furthermore, using both genetic disruption (Kir6.2 ablation) and pharmacologic blockade (tolbutamide), we show that loss of functional KATP channels decreases the incidence of pacing-induced re-entry and prolongs repolarization in RGS4-deficient atria. Our findings are consistent with the conclusion that enhanced KATP channel activity may contribute to pacing-induced re-entrant rotors in the RGS4-deficient mouse model.

Atrial arrhythmias are very common clinically relevant conditions that are strongly associated with aging and parasympathetic tone. Additionally, ATP-sensitive K+ (KATP) channel activation has been reported to facilitate the development of re-entrant atrial arrhythmias. Since KATP channels are direct effectors of Gαi/o and RGS4 is an inhibitor of Gαi/o-signaling, we here investigate whether KATP channel activity is increased under decreased RGS4 activity in a manner that enhances susceptibility to AF. We show that loss of RGS4 facilitates the induction of atrial arrhythmias under parasympathetic challenge both in whole animals and isolated atrial tissues. Furthermore, using both genetic disruption (Kir6.2 ablation) and pharmacologic blockade (tolbutamide), we show that loss of functional KATP channels decreases the incidence of pacing-induced re-entry and prolongs repolarization in RGS4-deficient atria. Our findings are consistent with the conclusion that enhanced KATP channel activity may contribute to pacing-induced re-entrant rotors in the RGS4-deficient mouse model.

In patients with normal hearts, increased vagal tone is associated with the onset of paroxysmal atrial fibrillation (AF). Vagal denervation of the atria renders AF less inducible. Circumferential pulmonary vein ablation (CPVA), with or without isolation (CPVI), is effective for treating paroxysmal AF, and has been shown to impact HRV indices, in turn reflecting vagal denervation. We examined the impact of CPVI on HRV indices over time, and evaluated the relationship between vagal modification and rate of recurrence of AF. High resolution ECG recordings were collected from 64 patients (49 male, 15 female, mean age 57.1±9.7) undergoing CPVI for paroxysmal (n=46) or persistent (n=18) AF. Recordings were made pre-procedure, and at intervals up to 12 months. Success was defined as no recurrence. After CPVI, 27 patients presented recurrence. Pre-procedure HRV variables did not differ from controls in patients with a subsequent successful procedure. However, patients with recurrence demonstrated significantly-reduced pre-procedure HRV compared both with controls, and with patients having successful procedures (39.6±23.4 & 33.7±19.2 vs 21.8±11.8, P =0.01 & P=0.04). Following the procedure, HRV was reduced vs pre-procedure in patients with successful procedures (33.7±19.2 vs 18.6±15.8, P=0.01), and did not differ from unsuccessful procedures over a 12 month FU. Both groups were reduced compared with a control value. There was no significant difference in HRV between patients who experienced recurring AF (n=9), and those who experienced AT or flutter (n=18). Our data suggests that patients experiencing recurrence after one procedure have reduced HRV that is not changed by CPVI; whereas patients with a successful single procedure experience a change in HRV variables that is sustained over a long period, but is no different post-procedure from patients experiencing recurrence. These data suggest that denervation associated with CPVI may benefit patients with normal vagal tone prior to the procedure, but that sustained denervation is not a critical factor in successful outcome after CPVI. / Thesis (Master, Computing) -- Queen's University, 2010-12-07 08:32:15.066

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Thesis (Ph. D.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 134-161).