Final answer:
Torsades de Pointes is a potentially dangerous form of ventricular tachycardia associated with a prolonged QT interval, often induced by certain drugs. It can be seen on an ECG by a 'twisting' pattern of the QRS complexes, and treatment may require defibrillation if the condition is severe.
Step-by-step explanation:
Polymorphic ventricular tachycardia that complicates drug-induced long QTc, known as Torsades de Pointes, is a specific type of cardiac arrhythmia characterized by a rapid, irregular heart rate. The condition is often associated with a prolonged QT interval on an electrocardiogram (ECG), which can be induced by certain medications. Electrocardiographic features of Torsades include a distinctive pattern where the QRS complexes appear to 'twist' around the baseline. Potassium channel blockers like amiodarone and procainamide are used to treat these dysrhythmias by affecting the repolarization phase of the cardiac action potential, impeding the movement of K+ through voltage-gated K+ channels and potentially prolonging the QT interval further.
Common ECG abnormalities connected to arrhythmias include issues such as second-degree block, atrial fibrillation, and third-degree block. Patients with severe arrhythmic symptoms may require urgent treatment including defibrillation to restore normal heart rhythm. Ventricular fibrillation, a more severe arrhythmia than Torsades, shows chaotic electrical activity on the ECG and is often fatal without immediate defibrillation.