What type of capture occurs at the tip cathode?

The concept of capture in the context of pacing refers to the ability of an electrical impulse generated by a pacemaker to stimulate myocardial tissue effectively, leading to contraction. At the tip cathode, when pacing is initiated, cathodal capture occurs. This type of capture is characterized by the direct stimulation of myocardial tissue by the negative electrode (cathode) at or near the end of the pacing lead.

Cathodal capture is associated with the polarization of myocardial cells under the influence of the negative charge associated with the cathode, which can lead to depolarization of the cardiac myocytes and subsequent contraction. This phenomenon is significant in pacemaker therapy, as the effectiveness of pacing depends on successful capture of the heart tissue.

In contrast, options like anodal capture pertain to scenarios involving an anode (positive electrode), which is generally not effective in stimulating cardiac muscle under typical pacing conditions. Septal and myocardial captures refer more to specific anatomical or physiological locations rather than the electrical capture process directly associated with the cathode. Thus, cathodal capture is the most accurate term describing the capture that occurs at the tip cathode.