Pulsed low-energy stimulation initiates electric turbulence in cardiac tissue

Interruptions in nonlinear wave propagation, commonly referred to as wave breaks, are typical of many complex excitable systems. In the heart they lead to lethal rhythm disorders, the so-called arrhythmias, which are one of the main causes of sudden death in the industrialized world. Progress in the treatment and therapy of cardiac arrhythmias requires a detailed understanding of the triggers and dynamics of these wave breaks. In particular, two very important questions are: 1) What determines the potential of a wave break to initiate re-entry? and 2) How do these breaks evolve such that the system is able to maintain spatiotemporally chaotic electrical activity? Here we approach these questions numerically using optogenetics in an in silico model of human atrial tissue that has undergone chronic atrial fibrillation (cAF) remodelling. In the lesser studied sub-threshold illumination régime, we discover a new mechanism of wave break initiation in cardiac tissue that occurs for gentle slopes of the restitution characteristics. This mechanism involves the creation of conduction blocks through a combination of wavefront-waveback interaction, reshaping of the wave profile and heterogeneous recovery from the excitation of the spatially extended medium, leading to the creation of re-excitable windows for sustained re-entry. This finding is an important contribution to cardiac arrhythmia research as it identifies scenarios in which low-energy perturbations to cardiac rhythm can be potentially life-threatening.

Clinically Significant Bradycardia and Hypotension Following Consumption of Betel Leaf in a Patient Treated for Chronic Atrial Fibrillation

Purpose A case of new onset bradycardia and hypotension following betel leaf consumption in combination with verapamil and metoprolol in an atrial fibrillation (AF) patient. Summary A 66-year-old Nigerian woman presented to the emergency department for evaluation of multiple near syncope episodes with underlying AF and slow ventricular response. After initial evaluation, the patient disclosed she had ingested several betel leaves that morning. She was admitted for observation of severe, progressive hypotension and symptomatic bradycardia. Her past medical history included AF, type 2 diabetes, asthma, obesity, hypertension and hypothyroidism. Her home medications consisted of spironolactone, metoprolol succinate, and verapamil ER. Upon admission, her home medications were held. She received IV fluids and atropine .4 mg IV as needed for symptomatic bradycardia. Approximately 18 h following admission, her vital signs stabilized and her labs returned to baseline. She remained stable and was discharged with a recommendation to continue her home medications at prescribed doses with reduced doses of verapamil and metoprolol and to follow-up with her primary care provider. Conclusion A patient with a history of AF developed significant hypotension and symptomatic bradycardia after betel leaf consumption resulting in an overnight critical care unit admission. The use of betel leaf is not common in the United States; however, practitioners should be cognizant of the use of complementary and alternative medications like betel leaf and incorporate this knowledge in patient evaluation. Patients consuming betel leaf or betel nut should be evaluated for cardiovascular effects as well as laboratory evaluation for organ damage.

Massive subgaleal hematoma in a 62-year-old man treated with apixaban as a consequence of mild head trauma

Subgaleal hematoma, accumulation of blood in the loose areolar tissue of the subgaleal space of the skull, is considered the most catastrophic complication of instrumental delivery. It is a rare finding in older ages, usually associated with coagulation disorders, severe head trauma leading to skull base fractures and accidental or abusive hair pulling. Complications include periorbital necrotising fasciitis, permanent blindness, infections and, in extreme rare cases, airway obstruction. Most cases of subgaleal hematoma resolve spontaneously, without the need of aspiration or drainage. We present here the case of a 62-year-old male on anticoagulant therapy with apixaban for chronic atrial fibrillation, who came to the emergency department after a car accident suffering from mild head trauma. The patient was complaining of a diffuse headache and physical examination showed a large ecchymosis and edema on the frontal area of the head. His neurological examination was unremarkable. Full-body computed tomography (CT) revealed a fracture of the third right rib. Twelve hours after admission, due to an excessive decrease of hematocrit, a second CT was performed. Although the images didn’t show intracranial hemorrhage or skull base fractures, a large and diffuse hematoma of the subaponeurotic space was observed and the diagnosis of subgaleal hematoma was confirmed. Massive subgaleal hematoma after mild head trauma is rather infrequent. Early diagnosis improves outcomes and can avert serious complications. Therapeutic strategy should be based on the severity of each case. In our case, conservative treatment appeared to be a valid alternative to surgery, as hematoma resolved spontaneously within 10 days. It is noteworthy that the use of anticoagulation is the only evident factor that could have been the precipitating factor for the development of the hematoma in our patient.

Clinical performance and exercise hemodynamics in patients with severe secondary tricuspid regurgitation and chronic atrial fibrillation

Objective The study aimed to investigate the functional capacity and hemodynamics at rest and during exercise in patients with chronic atrial fibrillation and severe functional symptomatic tricuspid regurgitation (AF-FTR). Background Symptoms and clinical performance of severe AF-FTR mimic the population of patients with heart failure with preserved ejection fraction (HFpEF). Severe AF-FTR is known to be associated with an adverse prognosis whereas less is reported about the clinical performance including exercise capacity and hemodynamics in patients symptomatic AF-FTR. Methods Right heart catheterization (RHC) at rest and during exercise was conducted in a group of patients with stable chronic AF-TR and compared with a group of patients with HFpEF diagnosed with cardiac amyloid cardiomyopathy (CA). All patients had preserved ejection fraction and no significant left-sided disease. Results Patients with AF-FTR demonstrated a low exercise capacity that was comparable to CA patients (TR 4.9 ± 1.2 METS vs. CA 4. 7 ± 1.5 METS; P = 0.78) with an average peak maximal oxygen consumption of 15 mL/min/kg. Right atrium pressure increased significantly more in the AF-FTR patients as compared to CA patients at peak exercise (25 ± 8 vs 19 ± 9, p < 0.01) whereas PCWP increased significantly to a similar extent in both groups (31 ± 4 vs 31 ± 8 mmHg, p = 0.88). Cardiac output (CO) was significantly lower among AF-FTR at rest as compared to CA patients (3.6 ± 0.9 vs 4.4 ± 1.3 l/min; p < 0.05) whereas both groups demonstrated a poor but comparable CO reserve at peak exercise (7.3 ± 2.9 vs 7.9 ± 3.8 l/min, p = 0.59). Conclusions AF-FTR contributes to the development of advanced heart failure symptoms and poor exercise capacity reflected in increased atrial filling pressures, reduced cardiac output at rest and during exercise sharing common features seen in HFpEF patients with other etiologies.

Spinal Cord Compression Secondary to a Spontaneous Spinal Haematoma in a Patient Newly Treated with Rivaroxaban

A 74-year-old patient anticoagulated with rivaroxaban for chronic atrial fibrillation presented to the emergency department with acute lumbar pain with progressive weakness of the lower limbs and inability to stand up. No previous trauma was reported. Neurological examination was consistent with a complete spinal cord syndrome at the level of T6. Magnetic resonance imaging showed the presence of spinal cord compression associated with signs of extensive intramedullary inflammation secondary to a haematoma. The patient underwent thoracic laminectomy with evacuation of an intradural haematoma. No intraoperative complications were described, but no clinical improvement had been achieved 15 days after the surgical intervention.

Surgical considerations for atrial functional regurgitation of the mitral and tricuspid valves based on the etiological mechanism

Atrial functional mitral regurgitation is a hot research topic in the field of mitral valve disease. Atrial functional mitral regurgitation is distinctly different from ventricular functional mitral regurgitation. The surgical indications for atrial functional mitral regurgitation have not been well established because of the small amount of evidence gathered to date. Mitral annular plication with an artificial ring is an essential surgical procedure because dilatation of the mitral valve annulus is a main factor underlying this pathology. Most of these cases can be treated by mitral annuloplasty alone. However, additional procedures, such as application of artificial chordae to the anterior leaflet for pseudo-prolapse, and posterior leaflet augmentation with a pericardial patch, are required in advanced cases with a giant left atrium and extremely enlarged mitral annulus. Chronic atrial fibrillation causes enlargement of the right and left atria. This pathology is a bilateral atrioventricular valve disease (dual-valve disease). Therefore, the conventional guidelines of single-valve disease should not be applied. Although atrial functional tricuspid regurgitation is underappreciated, tricuspid annuloplasty should be considered for most patients to prevent future regurgitation. In addition to the mitral and tricuspid valve procedure, integrated surgical management, including plication of the atrium and left appendage closure, is required. This review summarizes the current considerations of surgical treatment for atrial functional regurgitation of the mitral and tricuspid valves based on the etiological mechanism.

Stroke Severity Modified the Effect of Chronic Atrial Fibrillation on the Outcome of Thrombolytic Therapy

Background There is conflicting information regarding the impact of chronic atrial fibrillation (AF) on the outcomes of thrombolyzed patients with stroke. This study was designed to identify high-risk patients with chronic AF who had undergone thrombolysis treatment and to explore whether the baseline National Institutes of Health Stroke Scale (NIHSS) could be used to distinguish poor clinical outcomes in thrombolyzed patients. Methods A total of 164 acute ischemic stroke patients with chronic AF were enrolled in this study. The patients were categorized as having poor or favorable outcomes. A favorable 90-day outcome was defined as a modified Rankin Scale (mRS) score ≤ 2. Results Our study showed that the baseline NIHSS score of patients with poor functional recovery (mRS > 2) was significantly higher than that of patients with favorable outcomes (median 16 vs 12). Receiver operating characteristic (ROC) curve analysis of modified Rankin Scale(mRS) scores showed that a baseline NIHSS score of 14 was the optimal threshold for predicting unfavorable outcomes in patients with chronic AF. Multivariate logistic regression analysis showed that baseline NIHSS score > 14 was independently associated with poor outcomes (odds ratio = 4.182, 95% confidence interval 2.092–8.361). Conclusions Our study showed that stroke severity modified the effect of chronic AF on the outcome of thrombolytic therapy. The approach of stratifying stroke severity may be used to evaluate treatment strategies for decision making in intravenous thrombolytic therapy for acute stroke with chronic AF.