Ex-President Alberto Fujimori, convicted and jailed for corruption and crimes against humanity was hospitalized at a clinic Saturday.
"This morning, he showed signs of the beginning of tachycardia, and the decision was made to take him immediately to intensive care," Alejandro Aguinaga told AFP.
"He is now in stable condition and has been doing a series of tests."
Aguinaga noted that Fujimori, who led Peru from 1990-2000, experienced an "onset of supraventricular tachycardia," which is a sign of a heart problem, and the second such event for his patient in just 11 days.
The 79-year-old last went to hospital on August 29, for a six-day stay before returning to prison. In May, he also experienced arrhythmia. His doctor says he also suffers from hypertension.
He was convicted in 2007 for his role in killings by a death squad targeting supposed guerrillas when he was in power from 1990-2000.
Fujimori has since been in and out of hospital with heart, back and stomach trouble and growths on his tongue, which has been operated on several times for cancer.
The courts have rejected efforts by his family to have him freed from prison.