It can present with symptoms such as palpitation, presyncope or syncope.

We confirmed much lower rates of syncope and presyncope among young black donors.

He received two appropriate shocks which were associated with presyncope.

Incidence of syncope and presyncope was compared between randomization groups using multivariable logistic regression.

Background: Blood centers rely heavily on adolescent donors to meet blood demand, but presyncope and syncope are more frequent in younger donors.

Our adolescent donors had lower overall syncope and presyncope rates than similar populations in the United States, limiting the statistical power of the study.

Conclusion: Preloading adolescent donors with 500 mL of water did not have a major effect in reducing syncope and presyncope in South African adolescent donors.