- Email: [email protected]
Wireless Holter transmission in suspected dysrhythmias
Journal of Electrocardiology 39 (2006) S54 – S56 www.elsevier.com/locate/jelectrocard
Wireless Holter transmission in suspected dysrhythmiasB Sabine Schickendantz, MD, Frank Pillekamp, MD, Mathias Emmel, MD, Narayanswami Sreeram, MD, Konrad Brockmeier, MD4 Department of Pediatric Cardiology, Universitaetsklinikum Koeln, 50924 Ko¨ln, Germany Received 4 May 2006; accepted 18 May 2006
Abstract
Background: In patients with a history of possible dysrhythmias, documentation of an episode is mandatory before any form of treatment is given. Holter recordings with wireless telemetry offer the possibility of continuously recording electrocardiograms for days or even weeks with instantaneous analysis of the data in the physician’s office. Methods: Thirty-seven patients (20 male; median age, 8.4 years; range, 0.1-22 years), were investigated by using a telemetric Holter system (M120, Schiller, Switzerland), that is, intermittent transmission of the electrocardiographic data to a remote server using cell phone frequencies, with a median duration of the recordings of 6.5 days (range 1-42 days). Results: Recording quality was sufficient in all patients. Problems were related to electrode disconnections only, which were adjusted by contacting the patients. Twenty-eight of 37 recordings showed decisive findings. Of the 28 patients, no treatment was indicated in 16 patients, as subjective symptoms did not correlate with dysrhythmias; psychotherapy was indicated in 2 patients; antiarrhythmic medication was initiated or intensified in 5 patients; radiofrequency ablation was successfully performed in 5 patients; and 1 patient received an ICD. In 6 of 9 patients with negative Holter findings, a loop recorder implantation (Medtronic, Minneapolis, Minn) was indicated. In 1 patient, no dysrhythmias were recorded; however, when invasively investigated, ventricular tachycardia was detected and successfully treated by radiofrequency ablation. In 2 patients, no decision has been made to date. Conclusions: Wireless Holter recordings are useful in detecting dysrhythmias with rare occurrence, are less expensive and less invasive compared with implantable loop recorders, and offer the patient rather wide geographic ranges with sufficient signal quality. D 2006 Elsevier Inc. All rights reserved.
Keywords:
Dysrhythmias in pediatrics; Diagnosis of dysrhythmias
Introduction The routine clinical workload in a larger pediatric unit caring for children with potentially lethal disturbances of the conduction system, or tachyarrhythmias, includes reported episodes of palpitations or syncope occurring infrequently. The typical 24-hour Holter recording will not necessarily provide the information needed for further decision making. In addition, prolonged recordings for more than 72 hours, which can be achieved with modern memory chip technology, may possibly fail to document the suspected pathology. We and others have used an implantable loop recorder, B
Part of the work was supported by Kroschke-Stiftung fqr Kinder (http://www.kinderbuendnis.de/) and Langenfelder Kinderherzhilfe g. V., Eschenweg 2, 40764 Langenfeld, Germany. 4 Corresponding author. E-mail address: [email protected] (K. Brockmeier). 0022-0736/$ – see front matter D 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2006.05.022
which is very useful, but rather expensive and invasive.1 Recently, we have used a Holter system, which uses cell phone frequencies to provide electrocardiogram (ECG) data access from the office whereby the patient has the typical advantages of a Holter recording on a long-term basis without needing to attend the clinic every other day. Here we report our initial experience with this system in a pediatric setting. Materials and methods Digital Holter recordings of 37 patients (20 male; median age, 8.4 years; range, 0.1-22 years) were investigated by using a telemetric Holter system (Schiller, Switzerland), that is, intermittent transmission of the ECG data to a remote server, using cell phone frequencies with a median duration of the recordings of 6.5 days (range, 1 -42 days).
S. Schickendantz et al. / Journal of Electrocardiology 39 (2006) S54 – S56
The Holter system (MT-120, Schiller, Switzerland) consists of a regular signal recorder for 2 channels, hooked up to a cell phone transmitter working in a commercial network setting (Fig. 1). Analog-to-digital converting rate is 0.5 MHz per channel with a resolution of 0.005 mV/LSB. A set of 1.5-V AAA batteries provided power supply, which usually lasted for 48 hours, after which replacement of the batteries is required. Transmission of the data to the server in the ECG laboratory (GSM 900 or 1900-MHz band, data transmission speed up to 9.6 kB/s, maximum transmission power of 2 W) was achieved by automatically dialing the reserved cell phone number of the Holter system via the data server and consequently starting a download of the data. Automatic data download intervals can be preselected on the server in a range of 5 to 120 minutes. In the present study, we chose 30-minute intervals for all patients. ECG data analysis was typically performed twice daily or when the patient’s situation required a more immediate evaluation of the recordings. Online visualization of the ECG is not provided by the system. The first electrode positioning and Holter mounting was performed by a technician in our outpatient clinic, who also explained the essentials of the recording system to the patients or their parents and provided written instructions. A sufficient number of disposable electrode pads were also provided. The recording then continued until a relevant dysrhythmia was documented and decisions for further therapeutic steps could be made. Results The quality of the recordings was sufficient in all patients. Problems were related only to electrode disconnections or inappropriate contact, which then were resolved by contacting the patients. In 28 of the 37 patients, relevant findings resulted in long-term recording; thereby the decision not to treat was made in 16 of the 28 patients, as their reported subjective symptoms did not correlate with dysrhythmias in the Holter recordings. Of the 28 patients, 2 had no dysrhythmias but reported symptoms of syncope or presyncope, therefore requiring a referral to the psychiatrist. In both cases, the constellation of Munchausen syndrome
Fig. 1. Data downloading and analyzing setting for the M 120 Holter. The data server automatically downloads Holter recording data at a predefined interval (between 5 and 120 minutes) using GSM frequencies of the 900- or 1900-MHz band, respectively. The patient, unrestricted in his activity and geographic range, can be analyzed offline by request or once to twice daily, when appropriate.
S55
was confirmed. In 5 patients, an antiarrhythmic medication was initiated, or an ongoing treatment intensified, when radiofrequency ablation (RFA) therapy was not feasible. In 5 patients, RFA was successfully performed. In 1 patient, VT of multifocal origin was documented after surgery for congenital heart disease; this patient received an ICD in addition to medical therapy. Of 9 patients with negative Holter findings, in 6 patients a loop recorder implantation (Medtronic, Minneapolis, Minn) was indicated. In 1 patient, no dysrhythmias were recorded; however, when invasively investigated, ventricular tachycardia was detected and successfully treated by RFA. In 2 patients, no decision has been made to date. Discussion In patients with infrequent dysrhythmias, decision making for an adequate therapy can be a severe problem. Recently, the introduction of implantable loop recorders offered a solution to this problem.1 Investigation by implantable loop recorder significantly increases the diagnostic rate and ECG-directed treatments in a typical unselected syncopal population. Long-term follow-up of these patients has shown a significant subsequent reduction in syncopal events with improved quality of life.2 However, the relative invasiveness of implanting a loop recorder subcutaneously is not always easily accepted, particularly in children; therefore, we tried to look for more ideal sites for loop recorder implantation in children.3 The use of an external loop recorder is limited to the capabilities of the patient to successfully recognize and/or transmit the data to the server.4 Standard Holter recordings often fail to document the underlying rhythm disorder when occurrence of the suspected tachycardia is rare. In this study, our initial experiences with the wireless transmission of a Holter recording show acceptable results concerning the documentation of tachycardias, which took up to 42 days for their first occurrence. The quality of the wireless transmitted signals was comparable to a non–wireless-recorded one. Interestingly, the quality of a recording was further influenced by the right positioning of the disposable electrodes with good skin contact. Electrodes had to be repeatedly mounted by the parents or the patients during a long-lasting recording, typically 3 times a week, to avoid skin irritations. Possible skin irritation is also present in Holter recording settings with systems that provide longer recording times due to a larger memory for the physical storage of the data. In areas where cell phone use is frequent and adequate network facilities are provided, an application with rather unlimited geographic possibilities for the patient with a wireless system mounted can be of great value. Apart from the primary investment, the costs for the wireless Holter system are related to the fees that cell phone companies charge. In particular settings a trade-off between sampling rate and the time and amount of data transmission exists; that is, either costs for every call (between 5 and 120 minutes) or length of the data file can be more relevant.
S56
S. Schickendantz et al. / Journal of Electrocardiology 39 (2006) S54 – S56
The typical setting at our institution is an automatic data download every 30 minutes to the server. An issue can be the absence of an ICD relevant dysrhythmia. In several countries, a reduction of the primary cost for an ICD is offered when the diagnosis was made with the help of an implantable loop recorder of the same company. In children, however, the dominant form of treatment of life-threatening dysrhythmias is the use of radiofrequency catheter ablation therapy.5 The advantage of the wireless system we used here, compared with regular Holter systems with larger storage capacities, is the theoretical unlimited recording time until the underlying dysrhythmia has been documented and therapeutic consequences can be taken into account, with the patient staying at home. Our preliminary data suggest that the wireless Holter data transmission is a relevant
bridge between typical Holter systems and the implantable loop recorder in patients with syncopes of possible arrhythmogenic origin. References 1. Bloemers BL, Sreeram N. Implantable loop recorders in pediatric practice. J Electrocardiol 2002;35(Suppl):131. 2. Sreeram N, Hitchcock F, Bennink G. Abdominal implantation of loop recorders in infants and children. Ann Thorac Surg 2005;79:726. 3. Farwell DJ, Freemantle N, Sulke N. The clinical impact of implantable loop recorders in patients with syncope. Eur J Heart 2006;27:351 [Epub 2005 Nov 28]. 4. Gula LJ, Krahn AD, Massel D, Skanes A, Yee R, Klein GJ. External loop recorders: determinants of diagnostic yield in patients with syncope. Am J Heart 2004;147:644. 5. Simmers T, Sreeram N, Wittkampf F. Catheter ablation of sinoatrial reentry tachycardia in a 2 month old infant. Heart 2003;89:e1.
Wireless Holter transmission in suspected dysrhythmiasB Sabine Schickendantz, MD, Frank Pillekamp, MD, Mathias Emmel, MD, Narayanswami Sreeram, MD, Konrad Brockmeier, MD4 Department of Pediatric Cardiology, Universitaetsklinikum Koeln, 50924 Ko¨ln, Germany Received 4 May 2006; accepted 18 May 2006
Abstract
Background: In patients with a history of possible dysrhythmias, documentation of an episode is mandatory before any form of treatment is given. Holter recordings with wireless telemetry offer the possibility of continuously recording electrocardiograms for days or even weeks with instantaneous analysis of the data in the physician’s office. Methods: Thirty-seven patients (20 male; median age, 8.4 years; range, 0.1-22 years), were investigated by using a telemetric Holter system (M120, Schiller, Switzerland), that is, intermittent transmission of the electrocardiographic data to a remote server using cell phone frequencies, with a median duration of the recordings of 6.5 days (range 1-42 days). Results: Recording quality was sufficient in all patients. Problems were related to electrode disconnections only, which were adjusted by contacting the patients. Twenty-eight of 37 recordings showed decisive findings. Of the 28 patients, no treatment was indicated in 16 patients, as subjective symptoms did not correlate with dysrhythmias; psychotherapy was indicated in 2 patients; antiarrhythmic medication was initiated or intensified in 5 patients; radiofrequency ablation was successfully performed in 5 patients; and 1 patient received an ICD. In 6 of 9 patients with negative Holter findings, a loop recorder implantation (Medtronic, Minneapolis, Minn) was indicated. In 1 patient, no dysrhythmias were recorded; however, when invasively investigated, ventricular tachycardia was detected and successfully treated by radiofrequency ablation. In 2 patients, no decision has been made to date. Conclusions: Wireless Holter recordings are useful in detecting dysrhythmias with rare occurrence, are less expensive and less invasive compared with implantable loop recorders, and offer the patient rather wide geographic ranges with sufficient signal quality. D 2006 Elsevier Inc. All rights reserved.
Keywords:
Dysrhythmias in pediatrics; Diagnosis of dysrhythmias
Introduction The routine clinical workload in a larger pediatric unit caring for children with potentially lethal disturbances of the conduction system, or tachyarrhythmias, includes reported episodes of palpitations or syncope occurring infrequently. The typical 24-hour Holter recording will not necessarily provide the information needed for further decision making. In addition, prolonged recordings for more than 72 hours, which can be achieved with modern memory chip technology, may possibly fail to document the suspected pathology. We and others have used an implantable loop recorder, B
Part of the work was supported by Kroschke-Stiftung fqr Kinder (http://www.kinderbuendnis.de/) and Langenfelder Kinderherzhilfe g. V., Eschenweg 2, 40764 Langenfeld, Germany. 4 Corresponding author. E-mail address: [email protected] (K. Brockmeier). 0022-0736/$ – see front matter D 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2006.05.022
which is very useful, but rather expensive and invasive.1 Recently, we have used a Holter system, which uses cell phone frequencies to provide electrocardiogram (ECG) data access from the office whereby the patient has the typical advantages of a Holter recording on a long-term basis without needing to attend the clinic every other day. Here we report our initial experience with this system in a pediatric setting. Materials and methods Digital Holter recordings of 37 patients (20 male; median age, 8.4 years; range, 0.1-22 years) were investigated by using a telemetric Holter system (Schiller, Switzerland), that is, intermittent transmission of the ECG data to a remote server, using cell phone frequencies with a median duration of the recordings of 6.5 days (range, 1 -42 days).
S. Schickendantz et al. / Journal of Electrocardiology 39 (2006) S54 – S56
The Holter system (MT-120, Schiller, Switzerland) consists of a regular signal recorder for 2 channels, hooked up to a cell phone transmitter working in a commercial network setting (Fig. 1). Analog-to-digital converting rate is 0.5 MHz per channel with a resolution of 0.005 mV/LSB. A set of 1.5-V AAA batteries provided power supply, which usually lasted for 48 hours, after which replacement of the batteries is required. Transmission of the data to the server in the ECG laboratory (GSM 900 or 1900-MHz band, data transmission speed up to 9.6 kB/s, maximum transmission power of 2 W) was achieved by automatically dialing the reserved cell phone number of the Holter system via the data server and consequently starting a download of the data. Automatic data download intervals can be preselected on the server in a range of 5 to 120 minutes. In the present study, we chose 30-minute intervals for all patients. ECG data analysis was typically performed twice daily or when the patient’s situation required a more immediate evaluation of the recordings. Online visualization of the ECG is not provided by the system. The first electrode positioning and Holter mounting was performed by a technician in our outpatient clinic, who also explained the essentials of the recording system to the patients or their parents and provided written instructions. A sufficient number of disposable electrode pads were also provided. The recording then continued until a relevant dysrhythmia was documented and decisions for further therapeutic steps could be made. Results The quality of the recordings was sufficient in all patients. Problems were related only to electrode disconnections or inappropriate contact, which then were resolved by contacting the patients. In 28 of the 37 patients, relevant findings resulted in long-term recording; thereby the decision not to treat was made in 16 of the 28 patients, as their reported subjective symptoms did not correlate with dysrhythmias in the Holter recordings. Of the 28 patients, 2 had no dysrhythmias but reported symptoms of syncope or presyncope, therefore requiring a referral to the psychiatrist. In both cases, the constellation of Munchausen syndrome
Fig. 1. Data downloading and analyzing setting for the M 120 Holter. The data server automatically downloads Holter recording data at a predefined interval (between 5 and 120 minutes) using GSM frequencies of the 900- or 1900-MHz band, respectively. The patient, unrestricted in his activity and geographic range, can be analyzed offline by request or once to twice daily, when appropriate.
S55
was confirmed. In 5 patients, an antiarrhythmic medication was initiated, or an ongoing treatment intensified, when radiofrequency ablation (RFA) therapy was not feasible. In 5 patients, RFA was successfully performed. In 1 patient, VT of multifocal origin was documented after surgery for congenital heart disease; this patient received an ICD in addition to medical therapy. Of 9 patients with negative Holter findings, in 6 patients a loop recorder implantation (Medtronic, Minneapolis, Minn) was indicated. In 1 patient, no dysrhythmias were recorded; however, when invasively investigated, ventricular tachycardia was detected and successfully treated by RFA. In 2 patients, no decision has been made to date. Discussion In patients with infrequent dysrhythmias, decision making for an adequate therapy can be a severe problem. Recently, the introduction of implantable loop recorders offered a solution to this problem.1 Investigation by implantable loop recorder significantly increases the diagnostic rate and ECG-directed treatments in a typical unselected syncopal population. Long-term follow-up of these patients has shown a significant subsequent reduction in syncopal events with improved quality of life.2 However, the relative invasiveness of implanting a loop recorder subcutaneously is not always easily accepted, particularly in children; therefore, we tried to look for more ideal sites for loop recorder implantation in children.3 The use of an external loop recorder is limited to the capabilities of the patient to successfully recognize and/or transmit the data to the server.4 Standard Holter recordings often fail to document the underlying rhythm disorder when occurrence of the suspected tachycardia is rare. In this study, our initial experiences with the wireless transmission of a Holter recording show acceptable results concerning the documentation of tachycardias, which took up to 42 days for their first occurrence. The quality of the wireless transmitted signals was comparable to a non–wireless-recorded one. Interestingly, the quality of a recording was further influenced by the right positioning of the disposable electrodes with good skin contact. Electrodes had to be repeatedly mounted by the parents or the patients during a long-lasting recording, typically 3 times a week, to avoid skin irritations. Possible skin irritation is also present in Holter recording settings with systems that provide longer recording times due to a larger memory for the physical storage of the data. In areas where cell phone use is frequent and adequate network facilities are provided, an application with rather unlimited geographic possibilities for the patient with a wireless system mounted can be of great value. Apart from the primary investment, the costs for the wireless Holter system are related to the fees that cell phone companies charge. In particular settings a trade-off between sampling rate and the time and amount of data transmission exists; that is, either costs for every call (between 5 and 120 minutes) or length of the data file can be more relevant.
S56
S. Schickendantz et al. / Journal of Electrocardiology 39 (2006) S54 – S56
The typical setting at our institution is an automatic data download every 30 minutes to the server. An issue can be the absence of an ICD relevant dysrhythmia. In several countries, a reduction of the primary cost for an ICD is offered when the diagnosis was made with the help of an implantable loop recorder of the same company. In children, however, the dominant form of treatment of life-threatening dysrhythmias is the use of radiofrequency catheter ablation therapy.5 The advantage of the wireless system we used here, compared with regular Holter systems with larger storage capacities, is the theoretical unlimited recording time until the underlying dysrhythmia has been documented and therapeutic consequences can be taken into account, with the patient staying at home. Our preliminary data suggest that the wireless Holter data transmission is a relevant
bridge between typical Holter systems and the implantable loop recorder in patients with syncopes of possible arrhythmogenic origin. References 1. Bloemers BL, Sreeram N. Implantable loop recorders in pediatric practice. J Electrocardiol 2002;35(Suppl):131. 2. Sreeram N, Hitchcock F, Bennink G. Abdominal implantation of loop recorders in infants and children. Ann Thorac Surg 2005;79:726. 3. Farwell DJ, Freemantle N, Sulke N. The clinical impact of implantable loop recorders in patients with syncope. Eur J Heart 2006;27:351 [Epub 2005 Nov 28]. 4. Gula LJ, Krahn AD, Massel D, Skanes A, Yee R, Klein GJ. External loop recorders: determinants of diagnostic yield in patients with syncope. Am J Heart 2004;147:644. 5. Simmers T, Sreeram N, Wittkampf F. Catheter ablation of sinoatrial reentry tachycardia in a 2 month old infant. Heart 2003;89:e1.