Sustainable colonization of Mars using shape optimized structures and in situ concrete.

The major obstacle to Martian colonization is the mission cost which requires significant reduction. From the structural engineering point of view, importing materials and structural elements from Earth or massive excavations on the surface of Mars require an enormous amount of energy; thus, inflatable and under-surface structures as the main options for Martian colonization seem unrealistically expensive. Construction of affordable buildings onsite using only in situ sources may represent an ideal solution for Martian colonization.

Martian buildings: structural forms using in-place sources.

On Mars, structural loads and the low tensile strength of in-place Martian binders make existing solutions for Martian structures uneconomical because they are based on the terrestrial sources like inflatable units. Here we address this issue by introducing and analyzing three innovative structural forms in accordance with the structural engineering point of view using symmetric optimum parabolic rotated arch shapes and in-place waterless sulfur-based concrete. These forms minimize the tensile stresses under Martian structural loads.

Swallowing-induced Supraventricular Tachyarrhythmia.

Swallowing-induced supraventricular tachyarrhythmia is an extremely rare entity with unclear pathophysiology. A 55-year-old man presented with a 2-year history of worsening presyncopal symptoms triggered only by drinking liquids of any temperature. Results of a physical examination were unremarkable except for reproducible atrial tachycardias to 180 to 210 beats/minute documented on rhythm strips when the patient was given water to drink.

Effect of botulinum toxin on inducibility and maintenance of atrial fibrillation in ovine myocardial tissue.

Background: Aberrant vagal stimulation may promote the generation and propagation of atrial fibrillation (AF). Researchers have suggested that botulinum toxin (BTX), a neurotoxin that decreases neural vagal stimulation, may decrease the incidence of postoperative AF. The exact electrophysiologic mechanism underlying the observations and histopathologic alterations associated with BTX are unclear.

Comparative Efficacy of Nebivolol and Metoprolol to Prevent Tachycardia-Induced Cardiomyopathy in a Porcine Model.

Chronic tachycardia is a well-known cause of nonischemic cardiomyopathy. We hypothesized that nebivolol, a β-blocker with nitric oxide activity, would be superior to a pure β-blocker in preventing tachycardia-induced cardiomyopathy in a porcine model. Fifteen healthy Yucatan pigs were randomly assigned to receive nebivolol, metoprolol, or placebo once a day.

Left Atrial Appendage Ligation in Nonvalvular Atrial Fibrillation Patients at High Risk for Embolic Events With Ineligibility for Oral Anticoagulation: Initial Report of Clinical Outcomes.

Objectives: This study sought to assess long-term clinical outcomes in adults with nonvalvular atrial fibrillation (AF) who are ineligible for oral anticoagulation therapy and underwent left atrial appendage (LAA) ligation with the Lariat device.

Background: LAA exclusion has been used to prevent thrombus formation within the LAA in AF patients and is believed to decrease the risk of cardioembolic events.

Methods: LAA ligation with the Lariat device was performed in 139 patients with nonvalvular AF.

A Review of the LARIAT Suture Delivery Device for Left Atrial Appendage Closure.

The prevalence of atrial fibrillation (AF) is 1-2 % in the general population, and the risk of embolic stroke in AF patients is 4-5 times higher than that in the general population. AF-related strokes are often severe, and the rate of permanent disability is much higher among individuals who have AF-related strokes than in those who have strokes unrelated to AF. In patients with AF, more than 90 % of thrombi originate from the left atrial appendage (LAA).

Endocardial (Watchman) vs epicardial (Lariat) left atrial appendage exclusion devices: Understanding the differences in the location and type of leaks and their clinical implications.

Background: Watchman and Lariat left atrial appendage (LAA) occlusion devices are associated with LAA leaks postdeployment.

Objective: The purpose of this study was to compare the incidence, characteristics, and clinical significance of these leaks.

Methods: We performed a multicenter prospective observational study of all patients who underwent LAA closure.

Safety and effectiveness of compassionate use of LARIAT® device for epicardial ligation of anatomically complex left atrial appendages.

Background: Percutaneous left atrial appendage (LAA) ligation using an epicardial suture system (LARIAT®, SentreHEART, Palo Alto, CA) has been used in patients with nonvalvular atrial fibrillation (AF) and contraindication to oral anticoagulation. However, complex LAA anatomy may preclude its use. We report the safety and effectiveness of compassionate use of first-generation LARIAT® device for epicardial ligation of large, complex left atrial appendages.

Cryoballoon pressure waveform change during balloon inflation is not a reliable predictor of adequate pulmonary vein occlusion.

Background: Cryoballoon ablation of pulmonary veins (PVs) is widely used to treat atrial fibrillation (AF). Successful ablation requires occluding the PVs by cryoballoon. Angiography is a standard method of assessing PV occlusion.

Contact-force recovery can predict cardiac perforation during radiofrequency ablation.

Background: During radiofrequency ablation (RFA), the ability to know whether a steam pop has led to cardiac perforation (CP) would be of profound clinical significance. We aimed to determine whether catheter contact-force characteristics can predict whether a steam pop during RFA causes CP.

Methods: We used a 7.

Initial experience with a novel percutaneous left atrial appendage exclusion device in patients with atrial fibrillation, increased stroke risk, and contraindications to anticoagulation.

Atrial fibrillation (AF) increases by fivefold a patient's risk for thromboembolic stroke. The main source of emboli in AF is the left atrial appendage (LAA). Therefore, LAA closure could reduce the risk for thromboembolic events in AF.

Fistula from right internal mammary artery to superior vena cava after use of a laser sheath to extract a pacemaker lead.

A 55-year-old woman presented with dyspnea on exertion due to a right internal mammary artery-to-superior vena cava arteriovenous fistula that occurred after pacemaker lead extraction with a laser sheath. The fistula was successfully repaired by placing a covered stent in the right internal mammary artery. In this unusual location, endovascular stenting is a reasonable alternative to coil embolization or surgical repair of an arteriovenous fistula resulting from laser lead extraction.

Orthostatic hypotension as a manifestation of vitamin B12 deficiency.

A 90-year-old woman with orthostatic hypotension and near-syncope was found to have a low-normal level of vitamin B(12) and no other medical findings that could explain her orthostasis. Her symptoms responded to vitamin B(12) replacement therapy. This case shows that vitamin B(12) deficiency can induce orthostatic hypotension and syncope that are correctable by vitamin B(12) replacement.

Marked attenuation of shock burden by the use of antitachycardia pacing therapy in a patient with an implanted cardioverter-defibrillator.

A 76-year-old man was admitted to our institution for elective exchange of his implanted cardioverter-defibrillator generator. Nine years earlier, he had been diagnosed with nonischemic cardiomyopathy and nonsustainable ventricular tachycardia. At that time, he had received a single-chamber implanted cardioverter-defibrillator, which was upgraded to a dual-chamber implanted cardioverter-defibrillator 3 years later.

Heterogeneity of left ventricular signal characteristics in response to acute vagal stimulation during ventricular fibrillation in dogs.

Studies have shown that long-term vagal stimulation is protective against ventricular fibrillation; however, the effects of acute vagal stimulation during ventricular fibrillation in the normal heart have not been investigated. We examined the effects of acute vagal stimulation on ventricular fibrillation in a canine model. In 4 dogs, we induced 30-second periods of ventricular fibrillation by means of intraventricular pacing.

The evaluation and management of electrical storm.

Electrical storm is an increasingly common and life-threatening syndrome that is defined by 3 or more sustained episodes of ventricular tachycardia, ventricular fibrillation, or appropriate shocks from an implantable cardioverter-defibrillator within 24 hours. The clinical presentation can be dramatic. Electrical storm can manifest itself during acute myocardial infarction and in patients who have structural heart disease, an implantable cardioverter-defibrillator, or an inherited arrhythmic syndrome.

Tachycardia-mediated cardiomyopathy and the permanent form of junctional reciprocating tachycardia.

Permanent junctional reciprocating tachycardia, or atrioventricular reentrant tachycardia utilizing a slowly conducting posteroseptal accessory pathway, is a rare form of reentrant supraventricular tachycardia in children and adults. The characteristic features of this narrow complex tachycardia are a long RP interval and inverted P waves in the inferior leads. This form of accessory-pathway-mediated tachycardia, which is usually incessant, can lead to a tachycardia-induced cardiomyopathy and congestive heart failure if left untreated.