In which rhythm are QRS complexes the same shape, size, and direction?

Monomorphic Ventricular Tachycardia is characterized by QRS complexes that are uniform in shape, size, and direction. This means that each QRS complex looks the same, indicating that the depolarization of the ventricles is occurring in a consistent manner, originating from the same electrical impulse or focus.

In contrast, Polymorphic Ventricular Tachycardia shows varying QRS shapes and sizes due to multiple foci of electrical activity or changes in the heart's conduction pathway. Ventricular Fibrillation is marked by chaotic electrical impulses leading to no effective ventricular contraction, resulting in disorganized and varying QRS complexes. An Idioventricular Rhythm, while showing regular QRS complexes, typically indicates a slower intrinsic rhythm originating from the ventricles rather than from a uniform tachycardic event.

Thus, the defining feature of Monomorphic Ventricular Tachycardia is the consistent appearance of its QRS complexes, which is essential in identifying the condition during cardiac rhythm analysis.