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Palmitoylcarnitine increases the intracellular sodium ion concentration by initiating sodium ion current during ischemia in adult rabbit ventricular myocytes. A spontaneous activation of sodium current occurs at as low as minus 120 millivolt membrane potential and the current follows a subsequent slow inactivation. The slow inactivation indicates a new modified channel for sodium ions. The increase in sodium ion concentration by palmitoylcarnitine also introduces transient inward current and increases the intracellular calcium ion concentration by sodium-calcium ion exchange.

A study conducted to determine the influence of the activation of the thrombin receptor on the changes in the intracellular Na+ during myocardial ischemia in an isolated rabbit papillary muscle preparation find that the thrombin-receptor activating peptide, SFLL, induces accumulation of arrhythmogenic lipid metabolite LPC within ischemic myocardium. The accumulation was due to the rapid increase in the intracellular Na+ concentration.

Studies on isolated rabbit ventricular cells reveal that palmitoyl carnitine induces transient inward current through intracellular and extracellular delivery. Cytosolic calcium concentration directly influence the process through elimination of the current. This process occurs in the presence of EGTA.

Atrial fibrillation, the most common form of sustained abnormal heart rhythms, involves a rapid and random heart rhythm originating in an upper chamber of the heart. This type of arrhythmia occurs in about 10 percent of persons over 60 years of age. Most patients adapt to the changes caused by atrial fibrillation, but often an abnormal blood clot (thromboembolism) may develop because of changes in blood flow, causing a heart attack or a stroke. Drug therapy sometimes helps, but when it does not, surgery is tried. Of the several types of surgical treatment of atrial fibrillation developed, none have proven adequate for eliminating the condition. New imaging techniques have made 'mapping' of an organ during surgery possible, and a study was undertaken to apply this technology to the identification of areas of abnormal electrical conductivity in the heart, which could then be by-passed by surgical incisions. Twenty-two patients underwent surgery using a new technique, the maze procedure, for atrial fibrillation. Eight (36 percent) of the patients developed complications during the month following surgery, including arrhythmias in all eight, postoperative bleeding in three patients, and stroke, pneumonia, lupus (an autoimmune disease), and cholestasis (interruption of the bile flow in the liver system) in one patient each. However, the complications were successfully treated and there were no deaths. Nine patients have required the insertion of pacemakers, and the procedure damaged the sinoatrial node (SAN) in two patients. The new surgical procedure treated fibrillation successfully in all 22 patients, and allowed treatment with a single drug to control atrial flutter (rapid beats of the upper chambers of the heart) in 14 percent of the patients. It restored normal rhythm in 77 percent of patients, while in the rest, a pacemaker was required. (Consumer Summary produced by Reliance Medical Information, Inc.)

This article presents information on coronary artery disease. Sudden cardiac death in the setting of coronary artery disease is usually secondary to the abrupt onset of a lethal arrhythmia--most commonly ventricular tachycardia leading to ventricular fibrillation. Sudden cardiac death is a problem of enormous magnitude, accounting for well over 300,000 deaths per year in the United States alone. Owing to the unexpected nature of these lethal arrhythinias, and the fact that warning symptoms, if present, are usually very brief, most deaths occur outside the hospital.