A small wireless device that detects abnormal and potentially dangerous heart arrhythmias may replace the Holter monitor as the preferred method for tracking electrical heart activity in ambulatory patients. The Food and Drug Administration-approved ZIO patch is compact, low-profile and water-resistant. It can be worn throughout normal activities.

Cardiac arrhythmias are common, but diagnosis can be difficult because the occurrences can be sparse and fleeting. A variety of clinical studies have demonstrated that the ZIO patch is better at diagnosing arrhythmias than the Holter monitor. It is preferred by patients and may be paving a new way for ambulatory heart monitoring.

Since the 1960s, the gold standard for these diagnoses has been the Holter monitor, an ECG-type device with five to seven leads connected to a central processing unit that continuously records electrical cardiac activity to help diagnose abnormalities over an extended period of time. Patients are asked to wear the Holter monitor for 24 to 48 hours which can be an annoyance because of its bulk and wires.

The Zio cardiac monitor by iRhythm is essentially a 2 × 5-inch stick-on patch with an electronic monitor embedded in it. When finished with the prescribed three to 14 day wear period, during which every heart beat is recorded, the patient simply drops the device in a pre-paid envelope to return by mail for analysis, avoiding the need for a return visit to the doctor's office. Within a few days, the prescribing physician receives a concise and comprehensive report from iRhythm analyzing every heart beat and the patient's diagnosis.

The Zio has no leads, no batteries, and it weighs just a few ounces for a comfortable and unobtrusive patient experience. A survey found that 81 percent of study participants preferred wearing the Zio patch over the Holter monitor, and 76 percent said the Holter monitor affected their daily living activities.

Sanjeev S. Hasabnis, DO, FACC, FHRS, of Cardiovascular Associates in Birmingham was the first physician in Alabama to use the patch. "Zio by iRhythm is an ambulatory cardiac monitoring device that is similar to being on a hospital cardiac monitor, but it works continuously while the patient goes about daily activities. The beauty of this device is that it provides complete monitoring with no interruption. There are no gaps which helps the diagnostic accuracy," Hasabnis says.

One problem with the Holter monitor is the electrodes can come loose which causes inaccurate recording. "That doesn't happen with the Zio patch," Hasabnis says. "We can also tailor the Zio device monitoring period to each patient for anywhere from three to 14 days."

The Zio device has no therapeutic capability. "Its primary goal is continuous cardiac rhythm monitoring and comprehensive rhythm analysis," Hasabnis says. "It is purely a diagnostic tool that can tell us if a patient needs a pacemaker or an ablation. It also can tell us if the patient needs a medication adjustment or blood thinning medicines."

Hasabnis says that Zio's ease of use has led to better patient compliance. A nurse attaches the patch on the patient's upper left chest area above the heart. "The small patch stays on continuously. The patient can shower, exercise and sleep in comfort. Another advantage of the ZIO patch is its absence of acrylic," he says. "Many patients are allergic to acrylic, which can cause a skin rash."

A heart arrhythmia can result in serious conditions that can lead to heart failure and, subsequently, death. The Zio patch is indicated for use on patients who may be asymptomatic or who may suffer from transient symptoms such as palpitations, shortness of breath, dizziness, lightheadedness, presyncope, syncope, fatigue, or anxiety.

Because of the size of the patch, Hasabnis says the tracing of heart rhythms is much better with the ZIO patch. "Our diagnostic yield is higher, and we get better information. Early studies on this device have been favorable, and we are excited about the possibilities of this new technology."