Beta-blockers can be identified by having the “-OLOL” suffix at the end of the generic name of a medication. Ex. Atenolol (Tenormin) and Metoprolol (Lopressor).
By blocking the effect of epinephrine, there is a decrease in the heart rate and myocardial contraction, resulting in a reduction of the cardiac output.
Vasodilatation occurs from the medication acting on beta-1 and beta-2 receptors that inhibits the effect of epinephrine and norepinephrine has on the system. By inhibiting normal sympathetic effect vasoconstriction is restricted.
Beta-blockers block the release of renin by the kidneys. This interferes with the RAAS, which ultimately decreases angiotensin II and aldosterone in the system. This increases sodium and water loss resulting in a decrease in arterial pressure.
When beta-1 receptors are blocked by beta-blockers there is a decrease in heart rate and contractility. When beta-2 receptors are blocked renin production decreases, which interferes with the RAAS. This mechanism prevents vasoconstriction and decreases arterial pressure by pulling sodium and water out of the system.
In recent years three beta-blockers that have shown to be effective in treating heart failure: Carvedilol (Coreg), Bisoprolol (Zebeta), and Metoprolol (Lopressor). These beta-blockers have shown to improve LV ejection fraction and slow the progression of heart failure. However, the dosage should remain low because decrease in contractility occurs with higher doses.
Angina Pectoris is also known as “stable angina.” This type of chest pain is due to an increase in oxygen demand from the heart and being unable to get adequate oxygenated blood to the needed area. This type of chest pain can be caused from exertion, emotional stress, smoking, or other factors. Beta-blockers should not be given to patient with prinzmetal angina, which is chest pain that occurs at rest.
Non-selective beta-blockers act on beta-2 receptors, which cause bronchoconstriction that can result in a life threatening asthma exacerbation in patients that have a history of asthma. If possible patient with asthma should not be given beta-blockers.Beta-blockers can be used to treat excessive electrical activity in the atrial nodes. Heart blocks are caused from a decrease in electrical excitability, and it is for this reason that beta-blockers should not be used in patients that have heart blocks.
Prior to administration, the nurse should check the BP and HR. If the patient’s heart rate or blood pressure is too low, medication may need to be stopped. Always confirm with provider on medication parameters.
Because this medication blocks normal signs of hypoglycemia such as diaphoresis or tachycardia, diabetic patients should be cautioned to monitor their blood glucose regularly.
This medication should not be discontinued abruptly. Stopping beta-blockers abruptly after long-term use can cause angina and dysrhythmias. Patients should be tapered gradually over 2 weeks.
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