What physiological response occurs in the left ventricle with severe aortic stenosis?

In severe aortic stenosis, the left ventricle experiences increased myocardial tension primarily due to the need to generate a higher pressure to overcome the narrowed aortic valve during ventricular systole. As the aortic valve becomes stenotic, the left ventricle must work harder to push blood through the obstruction, leading to increased pressure gradients across the valve. This increased workload results in enhanced myocardial wall tension as described by the law of Laplace, which states that tension in the wall of a ventricle is proportionate to the pressure within it and the radius of the ventricle.

As the left ventricle adapts to the increasing demands due to the aortic stenosis, different physiological changes occur like hypertrophy to cope with the increased stress and maintain cardiac output. However, this hypertrophy itself also contributes to increased myocardial tension, as the thickening of the wall further raises the tension required for contraction against the high afterload.

In summary, the increased myocardial tension is a direct consequence of the left ventricle working against the elevated pressure required to eject blood through a narrowed aortic valve, reflecting the physiological adaptations that occur in response to the increased afterload associated with severe aortic stenosis.