Pacemaker Malfunction-Review of Permanent Pacemakers and Malfunctions Encountered in the Emergency Department.

Pacemaker malfunction refers to a failure of the pacemaker to perform the desired cardiac pacemaking function. These malfunctions can occur anywhere within the system from the pulse generator and leads to the electrode-myocardium interface. These failures of sensing, capture, and inadequate pacing can have severe hemodynamic consequences, so rapid identification of specific dysfunction is critical to intervention and stabilization.

Hereditary Syndromes of Sudden Cardiac Death.

Sudden cardiac death (SCD) describes the unexpected natural death from a cardiac cause within a short time period, generally 1 hour or lesser from the onset of symptoms, often due to a cardiac dysrhythmia. Overall, the most common cause of SCD is coronary artery disease but for patients aged younger than 35 years, the most common cause of SCD is a dysrhythmia in the setting of a structurally normal heart. This article will review the background, diagnosis, and management of the common hereditary channelopathies and cardiomyopathies associated with an increased risk of SCD in patients without ischemic heart disease.

Note: Low temperature calibration of a commercial differential scanning calorimeter.

A method for a direct calibration of temperature for a commercial differential scanning calorimeter is presented. The advantage of this calibration method is that it can be done for any number of selected temperatures and is not dependent on standards of known melting points in the temperature range of interest. The calibration presented in this note is for the temperature range from 91 K to 273 K, the temperature range of interest, but the range can easily be extended.

Hemispherical dielectric permittivity cell.

A three-terminal dielectric cell based on a hemispherical design is constructed for low-temperature measurements of dielectric permittivity. The cell has a small sample volume, is geometrically stable, and shows no frequency dependence of capacitance. Measurements on test samples are presented showing both cell constant stability data and the linearity of measured capacitance with dielectric constant.