How do slow dysrhythmias affect cardiac output (CO) and blood pressure (BP)?

Slow dysrhythmias, such as bradycardia, often lead to a decrease in cardiac output and blood pressure. This occurs because the heart's rate is insufficient to maintain an adequate volume of blood being pumped throughout the body. Cardiac output is calculated by the formula: cardiac output = heart rate x stroke volume. When the heart rate decreases significantly, even if the stroke volume remains constant or increases slightly, the overall cardiac output can drop.

In the case of bradycardia or other slow dysrhythmias, the heart is not contracting as often as necessary to meet the body's demands, particularly during times when increased blood flow is needed. For example, during exercise or stress, the body requires a higher cardiac output to ensure that all tissues receive enough oxygen and nutrients. With slow dysrhythmias, this demand is not met, leading to insufficient perfusion.

Additionally, if cardiac output is decreased, systemic vascular resistance may also be affected, often contributing to a drop in blood pressure as the heart is unable to maintain adequate flow against the opposition of the vasculature. Therefore, it is understood that slow dysrhythmias ultimately result in diminished cardiac output and can contribute to lower blood pressure, highlighting the gravity of these conditions