Implantable pacemakers with remote monitoring capabilities are giving cardiac patients a new lease on life. Isabel Lesto looks at three of these ingenious little devices.

Cardiac patients at risk of developing ventricular tachycardia or ventricular fibrillation have been given greater mobility and the freedom to travel at ease with the development of a new hi-tech implantable pacemaker and defibrillator.

The implantable cardioerter-defibrillator or ICD takes advantage of the latest wireless networking technology to enable cardiac patients with these devices to be constantly monitored by their physicians while on the move, no matter where they are in the world.

The ICD monitors heart events constantly and wirelessly communicates these to a nearby transmitter, which in turn sends the information, via either standard phone or mobile phone networks to a central computer. This information can then be accessed by a physician via the Internet at any time.

Middle East Health looks at three of these implantable cardiac devices with remote monitoring capability.

Today, patients can be fitted with a range of implantable devices and monitored by their doctors via phone lines or the Global System for Mobile Communication (GSM). Having a heart-to-heart with your cardiologist no longer requires travelling – as long as the patient has a communication channel and a monitoring device and their doctor has access to the Internet.

Biotronik’s Home Monitoring (HM) system was released in 2001 and, says Dr Robert Nitsche, country manager Biotronik Austria, it is the only pacemaker and ICD monitoring system available based on GSM, the mobile phone network.

The ICD is used to detect and stop serious ventricular arrhythmias and restore a normal heartbeat in people who are at high risk of sudden death.

The American Heart Association recommends that implantable cardioverter-defibrillators only be considered for patients who have a lifethreatening arrhythmia.

A recent study by the US National Heart, Lung, and Blood Institute demonstrated that implantable cardioverter-defibrillators are the treatment of choice instead of drug therapy forpatients who have had a cardiac arrest or heart attack and are at risk for developing ventricular tachycardia or ventricular fibrillation. Other studies suggest that 20% of these high risk patients would die within two years without an implantable cardioverterdefibrillator. With the device, the five-year risk of sudden death drops to 5%.

With Biotronik’s HM, the patient’s ICD provides current information about the patient’s cardiac condition as well as the status of the device and communicates this with the doctor via a CardioMessenger, a device similar to a mobile phone. The CardioMessenger receives data from the implant in the form of trend, event, or patient-triggered messages. It forwards this data to the Biotronik Service Center in Berlin via Short Messaging Service (SMS) on the GSM network.

Dr Nitsche insists this is secure, saying the SMS messages are encoded. At the centre they are decoded in a secure environment before being sent to the patient’s doctor, who is able to view and evaluate the data by logging on to a specific Biotronik Internet site.

There is one disadvantage of this system. The CardioMessenger, or any cellular phone for that matter, may interfere with the ICD if it comes within a 20-centimetre range of the device. Additionally, in places where mobile phones are prohibited, the instrument must be turned off.

However, there are enormous advantages for the patient. Mobility and the freedom to travel being top of the list. Wherever the patient is in the world, as long as there is mobile phone coverage, CardioMessenger will transmit data. Transmission takes place on a daily basis and the patient must be within four metres of the CardioMessenger.

All cardiac events are tracked by the system. In the event of a fall in heart rate, for example, transmission takes placeimmediately. However, as Dr Nitsche points out: “The system is for monitoring the heart and is not an alarm system.” Biotronik cannot respond to events, it simply transfers data.

Professor Herwig Schmidinger, co-director of the Electrophysiology Laboratory at the Medical University of Vienna, Austria, advocates HM. “My initial reaction when I heard about the system two years ago was absolutely positive,” he says. “The idea behind this is fascinating. Of course, like any system you have to get used to it, but afterwards it makes life much easier.”

When he first started using HM, updates were sent to him via fax. These days he receives e-mail every two weeks. “You can programme the monitoring at a time that is convenient to you.” The advantage for patients is that follow-up visits can be tailored to their situation. And for hospitals the advantage is costsavings. “Over the past 10 years we have received ore than 15,000 patient visits. In only 20% of these did we have to take action,” says Professor Schmidinger.

Not a single patient has ever objected to using HM, he claims. “One of my patients is a businessman who travels to the East a lot. He feels more protected and comfortable because he knows he will be connected to GSM in those countries.” He adds the system has prevented potential complications. “We have detected device malfunctions and lead breaks and were able to call patients in and hange the device.

Without remote monitoring, should the device malfunction soon after a physical check-up, the cardiologist will not know this until the next scheduled check-up. The patient then has to live with a nonfunctioning system for three months.” CareLink, first used in 2001 is Medtronic’s answer to the Internet-enabled pacemaker, and Housecall Plus, launched last year, is St Jude Medical’s response.

Both have similar advantages. But, unlike Biotronik’s GSM-based service, they use standard phone lines. Nearly 20,000 patients, from 250 clinics mainly in the US, use CareLink. The CareLink Monitor looks like a small answering machine and can be used at home or
while travelling. At prescheduled intervals, or if the patient experiences an event they feel is abnormal, the patient plugs the monitor into a phone socket. Within a few minutes, the patient's doctor can log on to a secure website and view the information ommunicated
by the device.

The service focuses on the US market but Medtronic is considering conducting pilots in other countries. “It’s difficult to export the technology to other countries because of the different telecommunications networks,” explains spokesperson Valerie Lind. “chieving medical reimbursement is another stumbling block.”

Currently US patients travelling to some countries, such as Italy, can use the service, as long as CareLink receives advance notice. Doctors, on the other hand, can travel anywhere in the world and access their patient’s data via the Internet. “Many patients tell us they feel more connected than in a scheduled devicecheck visit,” says Lind.

“Device-checks are pretty simple, but when the physician needs to see lots of patients it is harder to spend quality time.” St Jude Medical’s Housecall Plus system, approved for use in the US, is, according to the company, the world's first monitoring system to transmit complex ICD data in real-time over standard telephone lines. “Unlike other ICD-monitoring systems that store only limited data for review later, Housecall Plus has a medical professional analyse the transmissions immediately and communicate with the patient.”

Keeping pace

All three companies ensure their devices and remote monitoring systems keep pace with developments in heart failure treatment, one such development being cardiac resynchronisation therapy (CRT), also known as biventricular pacing.

Typical pacemakers pace only the right ventricle. This can result in an asynchronous contraction between the right and left ventricles.

CRT reco-ordinates the beating of the two ventricles by pacing them simultaneously. Timely pacing can significantly improve the patient’s physical capacity and quality of life.

Biotronik announced the market release of Kronos LV-T, its first CRT ICD with Home Monitoring, in December last year. “Telemedicine is a fastgrowing market,” says Dr Nitsche. “ICDs are growing at 20% a year and biventricular pacing is the fastest growing trend in pacemakers and ICDs.

” Biotronik promises that through remote monitoring of the device, doctors will be able to heck whether a patient’s heart is being completely resynchronised, obtain important predictors about decompensation, hospitalisation, mortality, detection of severe comorbidity early on and draw conclusions from a patient’s activity and quality of life.

Medtronic’s latest offering is the InSync Sentry, currently available in Europe and Canada. It received FDA approval in November last year. It will be linked to the CareLink system in the US. The InSync Sentry is the world’s first CRT-D device with automatic fluid status monitoring, which can be programmed to alert patients and clinicians to changes in fluid accumulation in the lungs and thoracic cavity. When used with other standard clinical assessments, this indicator offers the potential for early warning of fluid accumulation and appropriate clinical response.