Final answer:
Procainamide infusion is contraindicated in stable wide-complex tachycardia if the patient has a pre-existing heart block or long QT syndrome.
Step-by-step explanation:
Procainamide is commonly used for the management of stable wide-complex tachycardia. However, there are certain conditions in which the use of procainamide infusion is contraindicated. One contraindication is the presence of a pre-existing heart block, such as second- or third-degree atrioventricular (AV) block. Procainamide can further slow down the conduction between the atria and the ventricles, which can worsen the heart block. In such cases, alternative treatment options should be considered.
Another contraindication is the presence of long QT syndrome (LQTS) or other conditions that predispose the patient to develop Torsades de Pointes, which is a potentially life-threatening arrhythmia. Procainamide can prolong the QT interval on the electrocardiogram, which can increase the risk of Torsades de Pointes. Therefore, it should be avoided in patients with these conditions.
It is important to consult with a healthcare professional before initiating procainamide infusion to ensure that the medication is safe for the individual patient.