Carnation Ambulatory Monitor (CAM; Bardy Diagnostics, Inc.) is a P-wave centric electrocardiogram (ECG) patch monitor for people with suspected cardiac arrhythmias. The device can monitor a person remotely for up to 14 days. The device is placed along the sternum to optimise P-wave signal capture. The device comprises of a battrode which has 2 electrodes, one below where the monitor will clip in and the second located on the xyphoid point. The battrode has a slim hourglass shape and has long-term adhesive (suitable for sensitive skin) to hold the device in place on the skin. A recorder clips into the battrode before being attached to the sternum. The recorder has a button which is pressed to start recording and is then additionally pressed when the patient is experiencing a symptom. The timings of the start of the recordings and symptom events needs to be recorded in the supplied patient diary.
After the CAM patch has collected recordings for up to 14 days, the device is posted back to the hospital or external data processing centre for analysis. The CAM patch is linked to ECG analysis services and tools. After data are collected, a secure web-based portal is used for uploading and analysing ECG data, accessing and managing patient reports. The data can be analysed internally or by the company's ECG technicians who will prepare a report. The cardiologist would receive a full report within 2 working days. The report shows the ECG traces with different time scales (8 seconds, 56 seconds and 40 minutes) to provide context around an episode or event.
The company claims the device has a low noise floor, leading to more accurate and clearer signal detection than similar devices. The device can be worn for up to 14 days, unlike a Holter monitor which is generally used for between 24 and 48 hours, which makes it suitable for people with symptoms of arrhythmia that happen more than 24 hours apart. The device is also wire free and is water resistant, meaning that it can be worn in the shower and during exercise. However, users are advised to avoid showering or strenuous exercise for at least 24 hours after applying the patch. They also recommend avoiding environments or activities that lead to excessive sweating and advise against any activity which involves fully submerging the device in water, such as swimming or submerging the device whilst bathing.
NICE's guideline on atrial fibrillation states that standard care for people with suspected arrhythmias is assessment using manual pulse palpation followed by an ECG. In people with suspected paroxysmal atrial fibrillation undetected by standard ECG recording, use of a 24-hour ambulatory ECG monitor is recommended in people with suspected episodes less than 24 hours apart. An event recorder ECG is recommended for people with symptomatic episodes more than 24 hours apart.
The following publications have been identified as relevant to this care pathway:
The CAM is indicated for detecting cardiac arrythmias in anyone weighing 10 kg or more. This includes using the device for diagnosing paediatric arrhythmias. The device can be fitted in a clinic or at home by a patient. Once used, the device can be posted back to the hospital or an external centre for analysis. The device pack comes with instructions for placing and activating the device and a patient diary. The device would be prescribed by a consultant cardiologist in a secondary or tertiary care setting. Patients need to press the button on the device and record the time and date in their diary if they experience any symptoms of their suspected arrhythmia.
The cost of the device depends on the number of days the device is used for, if the analysis is done externally, and if the device is posted. This leads to a cost between £110 and £145 per person (if the analysis is done in the hospital) or £150 to £200 per person (if the analysis is done externally by the company):
2-day monitoring, £110 (excluding VAT)
7-day monitoring, £125 (excluding VAT)
14-day monitoring, £140 (excluding VAT).
Reporting costs are £40 per person for the 2- and 7-day service and £55 for the 14-day report. If the reporting is done in the hospital there are no reporting costs. If the device is directly mailed to the patient, there is an extra charge of £5 for the postage and administration costs. If the device is fitted in a clinic there are no additional postage charges. The company states that most devices would be fitted in a clinic.
The Zio XT monitoring services cost £265 per patient (excluding VAT). This figure includes the cost of the biosensor and the cost of analysing and reporting the data.
The CAM patch is currently being used at 18 NHS hospitals. It is a single-use device which could be used as an alternative to the Holter monitor. This device can be used for up to 14 days, meaning that longer recordings can be done compared with Holter monitors. Because the device can be posted back, an additional hospital appointment is not needed.
The company offers free training on device usage, fitting and data analysis (using their software). The software is provided for free and can be installed on as many computers in the hospital as needed.