Left atrial mechanical responses to right ventricular pacing in heart failure patients: implications for atrial fibrillation.

BACKGROUND: RV pacing (RVP), even with preserved atrioventricular (AV) synchrony, may lead to left atrial (LA) enlargement and atrial fibrillation. However, inciting events are unknown. We hypothesized that RVP acutely impairs LA function by mechanisms affecting atrial contraction and/or ventricular diastole. METHODS: LA function in ICD patients (n = 31, LVEF ≤ 40%) and controls (n = 14, LVEF > 50%) was contrasted between intrinsic conduction versus RVP during asynchronous (ICD, n = 17, control, n = 7), and synchronous (ICD, n = 14, control, n = 14) pacing at long (LAVd, 107 ±16 ms) and short (SAVd, 31 ± 5 ms) AV delays. LA maximal volume (LA(Max)), minimal volume (LA(Min)), and emptying fraction {LA(EmF) = (LA(Max) -LA(Min))/LA(Max)} were measured echocardiographically. Six-segment mean mitral annular tissue doppler E' (global E') assessed diastolic recoil during baseline and LAVd. RESULTS: In the ICD group, LA(Min) increased by 42% (P < 0.0009) during VVI, by 31% (P = 0.0002) during SAVd, and by 17% (P < 0.0007) during LAVd. LA(EmF) decreased by 44% (P < 0.0008), 27% (P < 0.0001), and by 15% (P = 0.003) during VVI, SAVd, and LAVd respectively. LA(Max) was unaltered. Global E' was reduced by 12%. In control, LA(Min) increased and LA(EmF) decreased significantly during VVI (82 and 58%) and SAVd (46 and 41%), but not during LAVd. CONCLUSION: In patients with LV dysfunction, RVP acutely impaired LA emptying, and increased minimal volume, most prominently when atrial contraction was impeded (VVI, DDD-SAVd) but also when completed (DDD-LAVd), indicating impaired diastolic recoil as an important mechanism. When LV function was normal, similar changes were present when atrial filling is impeded (VVI, SAVd), but not when completed (LAVd).

Transient Left Atrial Appendage Inversion During Transcatheter Closure Device Placement.

A 72-year-old female patient underwent left atrial appendage closure. During recapture of the occlusion device, transient inversion of the appendageal wall occurred. We describe the mechanism with real-time imaging and share our experience of handling this situation. To the best of our knowledge, this is the first case report of this unique recapture complication.

Potassium toxicity at low serum potassium levels with refeeding syndrome.

Refeeding syndrome is a life-threatening condition occurring in severely malnourished patients after initiating feeding. Severe hypophosphatemia with reduced adenosine triphosphate production has been implicated, but little data are available regarding electrolyte abnormalities. In this case, we report electrocardiographic changes consistent with hyperkalemia during potassium replacement after a serum level increase from 1.9 to 2.9 mEq/L. This was reversed by lowering serum potassium back to 2.0 mEq/L. In conclusion, the patient with prolonged malnutrition became adapted to low potassium levels and developed potassium toxicity with replacement.

Management of hot tar burn using vitamin e ointment containing petroleum and polyoxyethylene sorbitan.

Tar burns are primarily an occupational hazard associated with the road paving or roofing industry. Management of tar burns requires safe and effective removal of solidified tar from the skin using a dissolution or emulsifying agent to prevent inflicting further injury and pain. We report a case of a patient with tar burns on 10% of his body surface area involving the lower arms bilaterally and splashes to the facial area. The tar was efficiently removed with Webber Vitamin E Ointment without toxicity, irritation, or other complications.

DNA amplification and hybridization assays in integrated plastic monolithic devices.

PCR amplification, DNA hybridization, and a hybridization wash have been integrated in a disposable monolithic DNA device, containing all of the necessary fluidic channels and reservoirs. These integrated devices were fabricated in polycarbonate plastic material by CO2 laser machining and were assembled using a combination of thermal bonding and adhesive tape bonding. Pluronics polymer phase change valves were implemented in the devices to fulfill the valving requirements. Pluronics polymer material is PCR compatible, and 30% Pluronics polymer valves provide enough holding pressure to ensure a successful PCR amplification. By reducing the temperature locally, to approximately 5 degrees C, Pluronics valves were liquefied and easily opened. A hybridization channel was made functional by oligonucleotide deposition, using Motorola proprietary surface attachment chemistry. Reagent transport on the device was provided by syringe pumps, which were docked onto the device. Peltier thermal electrical devices powered the heating and cooling functionality of the device. Asymmetrical PCR amplification and subsequent hybridization detection of both Escherichia coli K-12 MG1655 and Enterococcus faecalis DNAE genes have been successfully demonstrated in these disposable monolithic devices.