By Katherine Klingseis, firstname.lastname@example.org
Measuring a mere 44 millimeters across, the Fortify Implantable Cardioverter Defibrillator has the power to literally jump-start a heart, and the Mary Greeley Center in Ames is now the first to use it.
A defibrillator is a device commonly used to remedy life-threatening heart conditions, such as abnormal electrical activity in the heart, uncoordinated contraction of the cardiac muscles of the heart ventricles and fast heart rhythm. These heart abnormalities can lead to sudden cardiac death.
“This sudden cardiac death can be treated very effectively with a very high grade electrical shock to the heart to basically shut down the electrical system that’s working at a very fast rate, and then reboot or restart the heart to achieve a normal rhythm,” said Imran Dotani, cardiologist at Mary Greeley Medical Center and McFarland Clinic.
In comparison to older, bulkier defibrillators, ICDs can be implanted into the patient’s chest. An ICD constantly monitors the patient’s heart and can administer an electrical shock if it notices something abnormal.
The Fortify ICD can deliver the highest amount of stored and delivered energy of any ICD available. For patients with an enlarged heart; low ejection fraction, the amount of blood pumped by the heart into the body; advanced heart failure; or high defibrillation threshold, the amount of energy required to shock the heart back to normal rhythm; the ability of the ICD to administer 40 joules of energy is a blessing.
Dotani was the first doctor in Iowa to implant the Fortify ICD into a patient. He chose to implant the device because of its power and small size.
“[The first patient] was a small lady that I felt would benefit from a smaller implant device,” Dotani said. “You have to make an incision on the chest and put these leads into the heart, and then the device has to sit on top of the ribs, and can be easily seen in a thinner person.”
The procedure of implanting the device begins with the doctor making a two-inch long incision a few inches below the collarbone. The wires, leads, that deliver electrical shocks, sense the cardiac rhythm, and, if needed, pace the heart, are screwed into the heart muscle.
The generator, which is connected to the leads, is then placed inside a pocket. The generator is a computer system that can monitor the heart rhythm of both the top and the bottom chambers of the heart. The patient is put through many tests in order to make sure the ICD is functioning correctly.
“If someone is running, it will recognize that this is a normal rhythm coming from the top going to the bottom of the heart, and it will not shock them,” Dotani said. “If it recognizes that the upper chamber is only going at 60 beats per minute, but the lower chamber is going at 200 or 180, which means it is an abnormal rhythm, then the computer will recognize this rhythm and shock them.”
The first ICD that Dotani implanted was in 2005, and, since that time, he has implanted hundreds. Dotani believes ICDs will eventually be even smaller and will be able to operate on their own, without any connection to the outside world. The only thing holding scientists back in creating a smaller, non-connected implant is finding the correct battery source.
“The battery source has to be long enough, otherwise we have to change the battery every six or seven years, which is why it’s put on the chest wall, so we can get to it to change it,” Dotani said. “We don’t have a source that can continue to live there for 40 to 50 years in some younger people.”
(Originally posted on Iowastatedaily.com on July 5, 2010)