A Novel Patch for Heart Rhythm Monitoring

Is the Holter Monitor Obsolete?

Steven L Higgins


Future Cardiol. 2013;9(3):325-333. 

In This Article

Abstract and Introduction


A number of substantial improvements to the 60-year-old concept of the Holter monitor have recently been developed. One promising advance is the Zio® Patch (iRhythm Technologies, Inc., CA, USA), a small 2 × 5-inch patch, which can continuously record up to 14 days of a single ECG channel of cardiac rhythm without the need for removal during exercise, sleeping or bathing. Its ease-of-use, which enables optimal long-term monitoring, has been established in the ambulatory setting, although some insurance carriers have been reluctant to reimburse appropriately for this advance, an issue characteristic of other heart monitors, treated as 'loss-leaders.' In this article, in addition to discussing possible reasons for this reluctance, a novel model for direct-to-consumer marketing of heart monitoring, outside of the traditional health insurance reimbursement model, is also presented. Additional current and future advances in heart rhythm recording are also discussed. Such potentially revolutionary opportunities have only recently become possible as a result of technologic advances.


Over 60 years ago, a biophysicist and inventor, Norman 'Jeff' Holter, revolutionized cardiology, developing the first continuous recording of ECG data from an active patient. A prototype in 1947, Holter's first version, weighed over 80 lbs.[101] With the advent of transistors, Holter was able to reduce the product's size to fit in a large pocket, a concept he patented in 1965 and sold to Del Mar Avionics (CA, USA). While the Holter monitor became ubiquitous in the cardiologist's office, the technology was slow to progress. Advances in the subsequent half-century were relatively minor, only encompassing recording advances, from reel-to-reel tape to cassette tape to current digital formats.[1,101]

In 2006, a young cardiac electrophysiologist, Uday N Kumar, and others at the Stanford University Biodesign program (CA, USA) recognized that current monitoring technologies, including the Holter monitor, were ripe for a disruptive technological advance. Kumar and his team developed a new concept which he subsequently commercialized: a single-use, recyclable, single-channel recording patch called the Zio® Patch (iRhythm Technologies, Inc., CA, USA; Figure 1). The Zio Patch has been referred to as a 'big Band-Aid®' (Johnson & Johnson, NJ, USA) since it is only 2 × 5 inches in size, complete with electrodes, recording hardware and software, an event button for marking the time of symptoms and an adhesive that typically allows for continuous recording for up to 14 days.[2] The typical Holter monitor recording only comprises 24–48 h. The Zio Patch is a single-channel continuous recording format with a memory of up to 14 days of stored rhythms. Similar to other ECG recording devices, the frequency response is 0.15–34 Hz, input impedence >3 Mohm, differential range ±1.65 mV and resolution 10 bits.[102]

Figure 1.

iRhythm Zio® Patch (iRhythm Technologies, Inc., CA, USA).

The Zio Patch provides many other advantages to the Holter monitor besides length of recording. It is 'wireless', that is, it does not require the need for electrode wires. The traditional Holter monitor requires external wires and electrodes, which limit patient acceptance and ease-of-use. Another limitation of the Holter concept results from the need to disconnect the wires and electrodes for the patient to be able to shower or exercise, situations in which rhythm abnormalities may occur undetected. The Zio Patch can be worn continuously, even when bathing. Studies have demonstrated a significantly less than 1% water damage rate under normal use.[2,3]

Other aspects of the Zio Patch model are also revolutionary in concept. Due to its ease-of-application, devices can be stored in locations where prompt application may increase the likelihood of making a timely diagnosis, such as upon discharge from emergency rooms, outpatient clinics and primary care offices.[2] The patch is removed by the patient, without medical assistance, and returned in a small preaddressed box that accompanies the patch (Figure 2). Generally, patients are instructed to keep the patch in place for up to 14 days of continuous recording. However, if an index event of clinical significance, such as syncope, occurs, the patch can simply be removed and returned for earlier rhythm analysis. Unlike the Holter, which is typically scanned by a medical assistant, often with minimal training, the data collected by the Zio Patch is analyzed in minutes by the vendor using proprietary algorithms running on a cloud-based platform, designed to improve diagnostic yield through high sensitivity and specificity. These initial results are first over-read by a trained cardiac technologist whose sole responsibility centers on Zio Patch rhythm analysis. Results are provided to the ordering physician for rhythm interpretation by web-based electronic retrieval or fax, generally less than 7 days from patient removal (including return shipment). This novel concept for heart rhythm monitoring provides a major advance. Its ease-of-use has resulted in several innovative opportunities for rhythm analysis. For example, medical triage by a primary care or emergency room physician or physician extender may allow for documentation of a benign rhythm at the time of symptoms. In appropriately screened patients, this could result in more cost–effective use of healthcare resources, potentially avoiding the need for cardiology consultation and additional testing.[2]

Figure 2.

Zio® Patch boxes, also used for postage paid return.