An Italian man with two hearts (his own and a donor's) was resuscitated with a defibrillator after developing life-threatening abnormal heart rhythms.

The case report, published online Tuesday in the Annals of Emergency Medicine, describes a 2010 ER visit, in which a 71-year-old man experienced significant shortness of breath, a rapid heart beat and rapidly dropping blood pressure due to his own heart's experiencing major heart palpitations. Those irregular rhythms then spread to the donor heart, causing it to also beat at a dangerously high rate.

"We haven't ever seen anything similar to this case before," Dr. Mugna Giacomo, a cardiologist at Az.Ospedaliera Universitaria Integrata in Verona, Italy, told ABCNews.com. "It's unique because nowadays this kind of surgery is very very rare."

"These patients are at greater risk of abnormal heart rhythms because the native heart is generally compromised and sometimes might be affected by [abnormal heartbeats]," continued Giacomo.

After getting diagnosed with cardiomyopathy (deterioration of the heart) in 2001, the patient received a pacemaker, and then underwent a "double heart" procedure,  in which a donor heart is connected through chambers and blood vessels to the patient's own heart.  The surgery, known as a heterotopic procedure, allows the original heart to recover, authors explained, and if the donor heart fails, it can be removed and the original heart is able to function again.

The rare double heart surgery, first used in 1974, had only been performed 187 times between 1987 to 2007 in the U.S. For most patients, removing the recipient's heart works better than connecting it to the donor heart. Nevertheless, experts say the procedure is appropriate if a donor heart is not strong enough to function on its own, either because the heart itself is weak or the patient is too big for the heart. In 2009 a Texas patient experienced abnormal heart rhythm in his own heart, but survived because the donor heart continued to beat normally while physicians used medication to get the hearts back in sync.

ABC News Medical Unit's Elizabeth Chuang contributed to this report