Beta-1 blockers exert their effect by binding to the beta-1 receptor sites selectively and inhibiting the action of epinephrine and norepinephrine on these sites. Īeta-1 receptors primarily are found in cardiac nodal tissue, cardiac myocytes, other heart conduction pathway tissues, and in the kidneys. The prolonged PR interval rarely results in more than first-degree AV block in patients receiving maintenance therapy. In a few patients, combining a calcium channel blocker and a beta-blocker may cause a second-degree AV block. Beta-blockers have a negative dromotropic effect on the AV node by prolonging the AV nodal refractory periods which could prolong the PR interval. AV node conduction is the slowest and PR interval variations reflect changes in AV nodal activation time. The PR interval on the EKG defines the time needed for an impulse to travel through the atrium and AV nodal system to the ventricles. Slow calcium channel blockers and beta-blockers are medications that affect AV nodal function. The benefits of left ventricular function improvement may take 2 to 3 months to observe after initiation of medication.
0 Comments
|
Details
AuthorDiana ArchivesCategories |