Patient was educated on Beta blockers and their mechanism of action as follows:
- Beta blockers are drugs that inhibit the action of adrenaline on both the Beta-1 and Beta-2 receptors.
- Beta -1 receptors are present in the pacemaker cells of the heart. Action of adrenaline on these cells increase the heart rate. Inhibition of action of adrenaline on Beta-1 receptors by Beta blockers result in slowing of heart rate and decreases the force of contraction of heart muscle.
- Beta-2 receptors are present in the smooth muscle of the blood vessel and the respiratory tract (bronchus). Action of adrenaline on this smooth muscle results in relaxation of smooth muscle and contributes towards dilation of blood vessel and relaxation of bronchus. Inhibition of action of adrenaline on Beta-2 receptors result in vasoconstriction and bronchoconstriction. Vasoconstriction results in increased blood pressure and bronchoconstriction results in reduced airflow and difficulty breathing with exacerbation of asthmatic symptoms and shortness of breath.
- Reduction in heart rate by inhibiting action of adrenaline on Beta-1 receptors help with controlling atrial flutter, atrial fibrillation, and ventricular tachycardia, and slow down the heart rate. By slowing down the heart rate, they also contribute towards lowering the blood pressure.
- These medications also decrease the force of contraction of cardiac muscle. Reducing the force of contraction of heart muscle will bring about reduction in the amount of blood pumped out of heart, which also contributes to low blood pressure.
- The reduced heart rate and the force of contraction will also contribute to reduced work performed by the heart. As the work of heart is reduced, the oxygen requirement of heart also is reduced.
- Reduction in the oxygen requirement of the heart muscle will help situations of compromised cardiac function, such as, heart failure.
- These Beta blockers can be used to reduce the blood pressure, abnormally high heart rate, control arrhythmias, and to reduce workload on the heart in patients with compromised cardiac function. But, these medications should be used cautiously for the risk of bronchoconstriction and exacerbation of asthmatic symptoms with shortness of breath. Selective Beta-1 blockers that act only on Beta-1 receptors and have no action on Beta-2 receptors can also be an alternative.
