All of the following are reversible causes of sinoatrial node dysfunction EXCEPT:

All of the following are reversible causes of sinoatrial node dysfunction EXCEPT:

1.Hypothermia
2.Hypothyroidism
3.Increased intracranial pressure
4.Lithium toxicity
5.Radiation theraphy

solution:

Sinoatrial dysfunction is often divided into intrinsic disease and extrinsic disease of the node. This is a critical distinction, as extrinsic causes are often reversible and pacemaker placement is not required. Drug toxicity is a common cause of extrinsic, reversible sinoatrial dysfunction, with common culprits including beta blockers, calcium channel blockers, lithium toxicity, narcotics, pentamidine, and clonidine. Hypothyroidism, sleep apnea, hypoxia, hypothermia, and increased intracranial pressure are all reversible forms of extrinsic dysfunction. Radiation therapy can result in permanent dysfunction of the node and therefore is an irreversible, or intrinsic, cause of sinoatrial node dysfunction. In symptomatic patients, pacemaker insertion may be indicated.