Minerva medica
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The electrocardiogram shows a sequence of cardiac electrical events generated by individual electrical currents generated mainly by sodium (Na+), potassium (K+) and calcium (Ca++) ions transiting via specialized transport pathways, such as ion channels, inserted in the membranes of excitable cardiac cells. Na+ and Ca++, entering the cells, are messengers of activating, inward, depolarizing currents (INa, ICa), generating the QRS wave of the electrocardiogram, whereas K+, leaving the cells, carries outward repolarizing currents (e.g. Ito, IKr, IKs and IK1), generating the T wave of the electrocardiogram, which drives the cell to a rest condition. ⋯ Presently, drug candidates are routinely subjected to preclinical and clinical examination for cardiac safety, a property required by health authorities for any new medicine before allowing marketing authorization. Finally, before prescribing a medicinal product prolonging QT interval, a physician should carefully evaluate not only the disease he wants to treat but also the availability of equally effective, alternative drugs. The golden rule, to which such a prescription has always to abide, requires that the beneficial effects expected from a therapy should for each treated patient outweigh any possible adverse consequence, particularly when the latter one could be of lethal nature.