Sinus nodal dysfunction

Yamaji S, Imai S, Watanabe T, Takahashi N, Uenishi T, Matsudaira K, Sugino K, Yagi H, Kanmatsuse K. Cilostazol improved sinus nodal dysfunction induced by cibenzoline which was used for hybrid therapy in patients with paroxysmal atrial fibrillation. Ther Res 2002 23 882-6. 

Reiffel JA, Bigger JT, Jr., Cramer M, Reid DS. Ability of Holter electrocardiographic recording and atrial stimulation to detect sinus nodal dysfunction in symptomatic and asymptomatic patients with sinus bradycardia. Am J Cardiol. 1977 40 189-194. 

Also known as sinotrial (SA) syndrome, sinus nodal dysfunction, and Stokes-Adams syndrome. 

Patients with underlying sinus node dysfunction tend to have signihcant worsening of nodal function, frequently requiring pacemaker implantation. Corneal microdeposits develop in most adults receiving amiodarone. As many as 10% of patients complain of halos or blurred vision. The corneal microdeposits are reversible with stoppage of the drug. 

The adverse effects associated with the use of verapamil include constipation, sinus node blockade, prolongation of the PR interval, AV dissociation, hypotension, and pulmonary congestion." The risks may outweigh the benefits in patients with (1) a markedly elevated pulmonary capillary wedge pressure or pulmonary artery occlusion pressure, (2) a history of paroxysmal nocturnal dyspnea or orthopnea, (3) sick sinus syndrome or significant AV nodal disease in the absence of a permanent pacemaker, (4) low systolic blood pressure, and (5) a substantial outflow gradient.Verapamil should be avoided inpatients with heart failure owing to systolic dysfunction. There is no evidence that either /3-blockade or verapamil protects the patient from sudden cardiac death. 

Toxicity of Ca Channel Blockers The major adverse effect of intravenous verapamil or diltiazem is hypotension, particularly with bolus administration. This is a particular problem if the drugs are used mistakenly in patients with ventricular tachycardia misdiagnosed as AV nodal reentrant tachycardia. Hypotension also is frequent in patients receiving other vasodilators, including quinidine, and in patients with underlying left ventricular dysfunction, which the drugs can exacerbate. Severe sinus bradycardia or AV block also occurs, especially in patients also receiving P blockers. With oral therapy, these adverse effects tend to be less severe. 

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