Why does stress make LBBB (Left bundle branch block) more symptomatic?

Left bundle branch block (LBBB) can become more symptomatic under stress because stress increases the demand on the heart, making any underlying cardiac inefficiencies more apparent. Here’s why:

1. Increased Heart Rate: Stress activates the sympathetic nervous system, leading to an increased heart rate. This can exacerbate the delay in electrical conduction caused by LBBB, further impairing the heart’s ability to pump blood efficiently.
2. Impaired Ventricular Coordination: LBBB causes the left and right ventricles to contract out of sync. During stress, the heart must pump more forcefully and quickly to meet the body’s oxygen demands, making the lack of coordination more noticeable. This may lead to symptoms like fatigue, shortness of breath, or chest discomfort.
3. Reduced Cardiac Output: LBBB often reduces the efficiency of the left ventricle, which is already under greater strain during stress. This can make it harder for the heart to keep up with the increased demand, leading to symptoms.
4. Underlying Cardiac Conditions: LBBB is often associated with other heart problems, such as coronary artery disease or cardiomyopathy. Stress can worsen these conditions, leading to more pronounced symptoms.
5. Increased Blood Pressure: Stress can temporarily increase blood pressure, which puts additional strain on the heart, potentially worsening symptoms associated with LBBB.

If you experience worsening symptoms during stress, managing stress levels (e.g., through relaxation techniques, exercise, or medications) and consulting with a cardiologist for potential interventions can be helpful.