Quiz 22: Antiarrhythmic Drugs


The myocardial muscles force the blood to pump through the circulatory system. The contraction of the cardiac muscle known as myocardium generates the blood pressure in the arteries that is necessary to distribute blood throughout the body. The muscles in the heart are controlled by the movement of ions. The function of Na-K ATPase enzyme is to regulate the entry and exit of sodium, potassium and calcium and thus maintaining the intracellular environment of the heart. The function of digoxin drug is to inhibit Na-K ATPase enzyme. The inhibition of sodium pump causes increase in the calcium level in the myocardial cells that in turn increases the contractile force of the heart. Digoxin also stimulates the parasympathetic nervous system to induce decreased heart rate. Digoxin is generally used to manage atrial fibrillation and to control symptoms of heart failure. The function of digoxin drug is to inhibit Na-K ATPase enzyme and also increasing the calcium in the heart muscles. Thus the heart rate is reduced, and the force of myocardial contraction is increased.

The most hazardous complications reported in the patients with congestive heart failure are abnormalities in the concentration of electrolytes. The presence of either low or high level of electrolyte concentration can affect the electrical impulses of heart. This can further lead to development of arrhythmias. The deficiencies of magnesium and potassium can play an important role in the development of cardiac arrhythmias. It is known that the administration of drug Furosemide can cause a loss of both magnesium and potassium in the plasma and spaces present between the cells. According to the data given the level of creatinine in the serum is found to be increased in the patient. The increased creatinine level in the patient of congestive heart failure is a marker of poor cardiac output. This ultimately reduces the ability of a patient to tolerate treatment for heart failure.

The angiotensinogen-converting-enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are included in the class of balanced vasodilators. These drugs dilate both arteries and veins. The ACEIs act by inhibiting the ACE that ultimately reduces the formation of angiotensin II. The reduced formation of complex increases the process of vasodilation and excretion of sodium and water from the kidneys. Hence, the incorrect options are a, b, c and d. The second process is inhibition of ACE that ultimately decreases inactivation of bradykinin. The vasodilator present within the body is bradykinin. The action of bradykinin increases level of bradykinin in the plasma. Hence, the correct option is img .

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