Alterations in vasomotor control of coronary resistance vessels in remodelled myocardium of swine with a recent myocardial infarction

The mechanism underlying the progressive deterioration of left ventricular (LV) dysfunction after myocardial infarction (MI) towards overt heart failure remains incompletely understood, but may involve impairments in coronary blood flow regulation within remodelled myocardium leading to intermittent myocardial ischemia. Blood flow to the remodelled myocardium is hampered as the coronary vasculature does not grow commensurate with the increase in LV mass and because extravascular compression of the coronary vasculature is increased. In addition to these factors, an increase in coronary vasomotor tone, secondary to neurohumoral activation and endothelial dysfunction, could also contribute to the impaired myocardial oxygen supply. Consequently, we explored, in a series of studies, the alterations in regulation of coronary resistance vessel tone in remodelled myocardium of swine with a 2 to 3-week-old MI. These studies indicate that myocardial oxygen balance is perturbed in remodelled myocardium, thereby forcing the myocardium to increase its oxygen extraction. These perturbations do not appear to be the result of blunted β-adrenergic or endothelial NO-mediated coronary vasodilator influences, and are opposed by an increased vasodilator influence through opening of KATP channels. Unexpectedly, we observed that despite increased circulating levels of noradrenaline, angiotensin II and endothelin-1, α-adrenergic tone remained negligible, while the coronary vasoconstrictor influences of endogenous endothelin and angiotensin II were virtually abolished. We conclude that, early after MI, perturbations in myocardial oxygen balance are observed in remodelled myocardium. However, adaptive alterations in coronary resistance vessel control, consisting of increased vasodilator influences in conjunction with blunted vasoconstrictor influences, act to minimize the impairments of myocardial oxygen balance

Challenges and limitations in the diagnosis of atrioesophageal fistula

Atrioesophageal fistula (AEF) is a dire complication of atrial fibrillation ablation. The diagnostic yield of computed tomography (CT) chest, the role and timing of repeat testing, and the value of other investigations in the diagnosis of AEF is uncertain.We systematically reviewed published AEF cases to evaluate radiological, bedside, and biochemical investigations for AEF (registered on PROSPERO [CRD42017077493]).Eighty-seven articles with 126 patients (median age, 59 years; male, 71%) were included in the analysis. CT chest was performed in 88% (111/126) and was abnormal in 87%. A clear diagnosis of AEF (fistula/perforation) was only detected in 35% (34/97). Other major findings included free air in mediastinum (26%), left atrium (LA), or LA wall (24%). In 11 patients with normal/nonspecific initial CT chest, major abnormalities were detected in 91% (10/11) of repeat CT chest performed 6 days (median; range, 4-22) after initial scan. Initial CT head was normal in 51%; diffuse air emboli was identified in 79% (22/28). Initial transthoracic echocardiography was normal in 61% of cases. The spectrum of radiological abnormalities included Air (mediastinum/LA), Effusion (pleural/pericardial), Fistula/Perforation, and Thickening (esophagus/LA) - "AEF-Tests." Esophagram demonstrated contrast extravasation in 87% (13/15). Blood culture was consistently positive (100%; 28/28), particularly for streptococcus species (93%; 26/28).The diagnosis of AEF remains challenging. Clinicians should be aware of the limitations in the yield of CT chest, the variety of major abnormalities reported, the need for repeat testing, unique brain imaging findings, and the importance of positive blood cultures and raised inflammatory markers.Francis J. Ha, Hui-Chen Han, Prashanthan Sanders, Andrew W. Teh, David O' Donnell, Omar Farouque, Han S. Li

Atrioesophageal fistula: clinical presentation, procedural characteristics, diagnostic investigations, and treatment outcomes

Percutaneous or surgical ablation are increasingly used worldwide in the management of atrial fibrillation. The development of atrioesophageal fistula (AEF) is among the most serious and lethal complications of atrial fibrillation ablation. We sought to characterize the clinical presentation, procedural characteristics, diagnostic investigations, and treatment outcomes of all reported cases of AEF.Electronic searches were conducted in PubMed and Embase for English scientific literature articles. Out of 628 references, 120 cases of AEF were identified using various ablation modalities. Clinical presentation occurred between 0 and 60 days postablation (median 21 days). Fever (73%), neurological (72%), gastrointestinal (41%), and cardiac (40%) symptoms were the commonest presentations. Computed tomography of the chest was the commonest mode of diagnosis (68%), although 7 cases required repeat testing. Overall mortality was 55%, with significantly reduced mortality in patients undergoing surgical repair (33%) compared with endoscopic treatment (65%) and conservative management (97%) (adjusted odds ratio, 24.9; P<0.01, compared with surgery). Multivariable predictors of mortality include presentation with neurological symptoms (adjusted odds ratio, 16.0; P<0.001) and gastrointestinal bleed (adjusted odds ratio, 4.2; P=0.047).AEF complicating atrial fibrillation ablation is associated with a high mortality. Clinicians should have a high suspicion for the development of AEF in patients presenting with infective, neurological, gastrointestinal, or cardiac symptoms within 2 months of an atrial fibrillation ablation. Investigation by contrast computed tomography of the chest with consideration of repeat testing can lead to prompt diagnosis. Surgical intervention is associated with improved survival rates.Hui-Chen Han, Francis J. Ha, Prashanthan Sanders, Ryan Spencer, Andrew W. Teh, David O’Donnell, Omar Farouque, Han S. Li