A new system for at-home monitoring of ICD-CRT patients is about to become available. The Latitude^® Patient Monitoring System, manufactured by Guidant, Inc., utilizes wireless telemetry to perform interrogations and programming. This newest advance in technology brings with it some unique implications for quality patient care.

Figure 1.

The Latitude® Patient Monitoring System. Included is the ZOOM Latitude® programmer, scale and blood pressure equipment from A & D Medical, communicator, and the Contak® Renewal #RF CRT-D. Each component features wireless telemetry. (Used with permission from Guidant, Inc.).

Latitude System Components
       The Latitude® Patient Monitoring System has been developed for use with the Contak® Renewal 3 RF CRT-D. The components of the system include the ZOOM Latitude® programmer, the communicator, scales and a blood pressure cuff (Figure 1). The scales and blood pressure cuff are manufactured by A & D Medical for this system. Built into all components is wireless telemetry that allows the capture of weight, blood pressure and device data by the communicator, which is placed in a convenient location in the patient’s home. This data is then automatically transmitted to a data website, allowing clinician access. The impact of the system is multi-factorial.

Device Implant
       Use of the wireless ZOOM Latitude® programmer alters the way in which a device implant is performed. The programmer communicates with the ICD-CRT without wires; thus, a device may be programmed without a programmer wand. As a result, wound closure can take place while final programming is being done, decreasing total implant time. In addition, the potential for sterile field contamination by the presence of the programming wand is eliminated.

Table 1. “Red Alert” conditions. These messages are also shown with device interrogation.

- The daily check looks for: • Device battery has reached end of life (EOL) • High/low shock lead impedance • High/low shock lead impedance detected when attempting to deliver shock • High/low right ventricular pacing lead impedance • Low right ventricular intrinsic amplitude • High voltage detected on shock lead during charge • Tachy mode change due to magnet • Tachy mode set to value other than Monitor + Therapy • Possible device malfunction

Clinic Visits and Follow-Up
       Device checks are completed with the ZOOM Latitude® programmer without wires, and data acquisition is three times faster than with the previous programmer. As a result, device clinic visits are less time consuming.
       Phone call follow-up for missed transmissions will be reduced as data transmission occurs at home automatically without patient assist. Other ways in which follow-up is impacted include the MD notifications built into the system and the collection and online availability of vast amounts of information related to device performance and heart failure indicators.

MD Notifications
       The automatic daily device check performed by the at-home communicator may generate “red alerts,” which are the same warnings generated by in-office interrogations. These red alerts will be found on the website when the physician logs in. The physician is also notified by the Latitude website managers if an alert condition is present. Red alert conditions include battery end of life indication (EOL), issues of abnormal impedance, low RV amplitude, high voltage detection during a shock, tachycardia mode changes that have not been programmed, and possible device malfunction (Table 1).
       “Yellow alerts” are weekly alerts chosen by the physician for each patient. The heart failure specialist and the electrophysiologist may customize the alerts they receive to their specific areas of concern. Data contained within this category includes abnormally high or low amplitude and impedance for right ventricular, left ventricular and atrial leads, arrhythmia episodes and treatments, and ERI of the battery (Table 2).

Table 3. Heart Failure Report Data.

- My Alerts Trends • Events • Weight • Blood Pressure • Activity Log • Heart Rate • SDANN • HRV Footprint • Autonomic Balance Monitor Events Heart Rate Variability Histograms Brady and CRT counters Battery settings

Device Performance Data
       The online data available to the physician about device performance and status is virtually the same as that which is available with in-office interrogation. Screens may be accessed with data on the most recent EGM, events summaries, battery status, lead status, settings, general patient information and health summary.

Heart Failure Management Features
       A unique feature of this system is the inclusion of scales and a blood pressure cuff. Information about weight assists in the monitoring of fluid volume status and the effectiveness of the treatment plan. Monitoring of the daily blood pressure assists in the assessment of medication titration regimens. The scale and blood pressure cuff used in this system are optional, and use may be elected at implant or later during follow-up. When the patient uses the scale or the blood pressure cuff within 10 feet of the at-home communicator, these parameters are detected and transmitted to the Latitude website, thus putting more information in the hands of the heart failure specialist.
       The data available to the heart failure physician includes the red and yellow alerts plus a great deal of information which can be displayed in trend form. This includes trending about events, patient weight, blood pressure, activity log, heart rate, SDANN, HRV footprint, and autonomic balance monitor. In addition, histograms, bradycardia and CRT counters, and battery settings information are accessible (Table 3).

Use of the Communicator in the Home
       The Latitude communicator automatically collects patient information at the time prescribed by the physician. A telephone is plugged into the back of the communicator. Daily or weekly schedules for data acquisition can be programmed. The communicator is kept on a bedside table or in a location in which the patient spends much time. The patient must be within 10 feet of the device for wireless interrogation to occur. Compliance with data transmission schedules is virtually eliminated with this system, as it requires no thought or labor on the part of the patient. The communicator can also be used when the patient travels. If patient data is not received for a 14-day period, automatic call follow-up is initiated. Patient initiated transmissions require that the patient calls first in order for data upload to occur. The communicator sends the data to a storage system and the information becomes available to the physician on the Latitude website.

Table 2. “Yellow Alert” Conditions. These are selected individually by physician preference.

- Ventricular pacing leads • High right ventricular intrinsic amplitude • Low left ventricular intrinsic amplitude • High left ventricular intrinsic amplitude • Low left ventricular pacing lead impedance • High left ventricular pacing lead impedance Atrial pacing leads • Low atrial intrinsic amplitude • High atrial intrinsic amplitude • Low atrial pacing lead impedance • High atrial pacing lead impedance Arrhythmias • Shock therapy delivered to convert arrhythmia • Accelerated arrhythmia episode • ATR detected for more than 24 hours • Patient-triggered event stored Device Battery has reached ERI

       Once per week the communicator will ask the patient questions related to their quality of life/heart failure symptoms. Answers to these questions are tracked by the system to detect clinical changes. The questions include: “Are you feeling unusually fatigued”; “Have you felt faint or dizzy over the past few days”; “Describe the swelling in your ankles, legs or abdomen over the last few days”; “Describe your ability to walk or climb stairs over the past few days”; and “How many pillows did you sleep with last night?” (Table 4)

Latitude Website
       The Latitude website is a digital archive managed by Guidant for patient data collection. The data itself, however, is owned by the patient and the clinic. Capabilities of this system include the ability to email reports, print data, and save data to both a computer and/or an electronic medical record (EMR). It is also possible for the physician to schedule specific data device downloads, thus facilitating more efficient time management.
       The Latitude website also includes a patient page, allowing the patient access to information about their weight and blood pressure trends. This data availability helps to promote greater participation by the patient in their treatment plan. The data can be accessed by the physician from any location with secure password protection.

Table 4. Weekly Patient Symptom Report.

- Questions: • Are you feeling unusually fatigued? • Have you felt faint or dizzy over the past few days? • Describe the swelling in your ankles, legs, or abdomen over the past few days. • Describe your ability to walk or climb stairs over the past few days. • How many pillows did you sleep with last night? • How often did you wake up breathless last night?

Summary
       The Latitude system is unique in many ways. These include time-saving features, availability of more data to assist in patient management, enhanced patient compliance with transmissions, and opportunities for a more informed patient to be a partner in their care plan. This technology provides a glimpse at what should prove to be an exciting future for remote monitoring of patients.