Wolff-Parkinson-White syndrome is the second most common cause of supraventricular tachyarrhythmias in the western world and the most common cause in Asian countries such as China. The first gene responsible for this disorder was identified to be a mutation in the gamma 2 subunit of AMPK, which is encoded by the gene PRKAG2. This has now been confirmed in several families throughout North American and Europe. Six mutations all except one are missense mutations present in the gamma 2 subunit. The syndrome consistently exhibits preexcitation (short PV interval on the ECG), delayed upstroke of the QRS, and often is associated with impaired atrioventricular conduction as well as ventricular hypertrophy. Genetic animal models have been developed and are being explored to improve the diagnosis, prognosis, and treatment of this syndrome. Genetic testing is available through DNA sequencing but is performed at present only as a research tool.
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The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.