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An unusual electrocardiogram artifact: what is its source?
Journal of Electrocardiology 38 (2005) 337 – 339 www.elsevier.com/locate/jelectrocard
An unusual electrocardiogram artifact: what is its source? Nischita K. Reddya, Ramanna Merlab, Nonko D. Pehlivanovc, Pankaj J. Pasrichac, David L. Wared, Yochai Birnbaumd,T a Department of Neurology, The University of Texas Medical Branch, Galveston, TX 77555-0553, USA Department of Internal Medicine, The University of Texas Medical Branch, Galveston, TX 77555-0553, USA c Division of Gastroenterology, The University of Texas Medical Branch, Galveston, TX 77555-0553, USA d Division of Cardiology, The University of Texas Medical Branch, Galveston, TX 77555-0553, USA Received 25 April 2005; accepted 25 May 2005
b
Abstract
A diabetic female presented with nausea and vomiting. Her electrocardiogram showed sinus rhythm with two artifactual spikes, not synchronized with the cardiac rhythm. The patient had an implanted gastric electrical stimulation system for treating her diabetic gastroparesis. Recent DC shock for ventricular fibrillation during coronary angiography caused malfunction of the gastric pacemaker. D 2005 Elsevier Inc. All rights reserved.
Keywords:
Electrocardiogram; Artifactual spikes; Gastric electrical stimulation system (GES); Diabetic gastroparesis; Diabetis mellitus
1. Case A 52-year-old white female with severe diabetic gastroparesis and coronary artery disease requiring bypass grafting several years before presentation presented with nausea and vomiting. Fig. 1 shows her admission electrocardiogram (ECG). How should one interpret the artifact? Three years ago, a gastric electrical stimulation (GES) system (Enterra Therapy System, Medtronic, Minneapolis, MN; Fig. 2) was implanted to treat the patient’s nausea and vomiting from gastroparesis. During a cardiac catheterization performed a year before she presented to us, the patient received an external DC shock for ventricular fibrillation that occurred with intracoronary contrast injection. Following this, her symptoms of gastroparesis recurred. After interrogation, attempts at reprogramming the GES device failed. An evaluation by the manufacturer indicated that the DC shock had damaged the device’s battery and electrodes. The device was replaced, and the patient’s symptoms improved quickly. Three months later, the patient underwent coronary angiography for suspected myocardial ischemia, developed
T Corresponding author. Tel.: +1 409 772 2794; fax: +1 409 772 4982. E-mail address: [email protected] (Y. Birnbaum). 0022-0736/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2005.05.009
again ventricular fibrillation on intracoronary contrast injection, and received external DC shock. Her nausea and vomiting recurred after the procedure. Evaluation of the device showed that, although the generator continued to pace (creating the ECG artifact), one of the electrodes produced no electrical output, and its impedance could not be assessed. Reprogramming the body of the system as the positive pole and the remaining functional electrode as the negative pole produced no symptomatic improvement, and the system was eventually turned off. The patient currently awaits placement of another GES system. 2. Discussion A GES system stimulates the stomach musculature via 2 leads connected to a pulse generator. The leads may be implanted laparoscopically, and the pulse generator is placed in a subcutaneous pocket created in the abdominal wall. Adverse events reported with GES implantation have included device infections, device migration, stomach wall perforation, other postsurgical complications such as pulmonary embolism, aspiration pneumonia, and volvulus around the wires [1,6]. To our knowledge, this is the first report of GES malfunction caused by DC shock (PubMed and MEDLINE search; keywords: GES, cardioversion, gastroparesis, and pacer malfunction). Because GES is
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N.K. Reddy et al. / Journal of Electrocardiology 38 (2005) 337–339
Fig. 1. ECG showing sinus rhythm with nonspecific ST-T changes and QT-interval prolongation. Two artifactual spikes occur approximately 11.5 times per minute and are not associated with the QRS complexes.
being used more often to treat refractory diabetic gastroparesis [1- 4], it would not be surprising if more such events occur in these patients whose incidence of coronary events and cardiac arrhythmias is high. Obviously, we recommend evaluating GES devices after any DC shock, which unlike cardiac pacemakers, are not protected with filtered feed through. However, the more problematic and complex management difficulties may arise from device-device interaction in GES patients who may
also need an implantable cardioverter/defibrillator. An implantable cardioverter/defibrillator might misinterpret GES pacing stimuli as a stable rhythm and not sense— and thus not treat—ventricular tachycardia or fibrillation. This potential problem must be considered in any diabetic patient before GES device implantation. The GES device is configured to stimulate the stomach wall approximately 12 times a minute (with recurring on and off cycles of 0.1 and 5 seconds, respectively) [1,5,6] and with default voltages of 1 to 4 V. This is apparent in this patient’s admission ECG, where the large GES pacing artifacts are occurring approximately 11.5 times each minute, with an amplitude of 2.5 mV. These stimuli are not synchronized with the cardiac cycle and in theory could induce ventricular fibrillation by pacing during the vulnerable period of myocardial repolarization. However, this would require not only bad timing, but also a sufficiently large pacing impulse delivered on the epicardium. There have been no previous reports of such an occurrence. It is very unlikely that GES caused this patient’s ventricular fibrillation, given the context in which the arrhythmia episodes occurred (immediately after intracoronary contrast injection) [7].
References
Fig. 2. Abdominal x-ray showing the GES generator and its leads, sternotomy wires and clips placed at the time of coronary bypass surgery, and a nasogastric tube.
[1] Lin Z, Forster J, Sarosiek I, McCallum RW. Treatment of diabetic gastroparesis by high-frequency gastric electrical stimulation. Diabetes Care 2004;27(5):1071. [2] Lin Z, Forster J, Sarosiek I, McCallum RW. Effect of high-frequency gastric electrical stimulation on gastric myoelectric activity in gastroparetic patients. Neurogastroenterol Motil 2004;16(2):205. [3] McCallum RW, Chen JD, Lin Z, Schirmer BD, Williams RD, Ross RA. Gastric pacing improves emptying and symptoms in patients with gastroparesis. Gastroenterology 1998;114(3):456. [4] Parkman HP, Hasler WL, Fisher RS. American Gastroenterological Association technical review on the diagnosis and treatment of gastroparesis. Gastroenterology 2004;127:1592.
N.K. Reddy et al. / Journal of Electrocardiology 38 (2005) 337–339 [5] Clinical Policy Bulletins, number: 0678, Gastric pacing/gastric electrical stimulation. http://www.aetna.com/cpb/data/CPBA0678.html. [6] Medtronic Enterra therapy system. H990014 — Summary of safety and probable benefit. http://www.fda.gov/cdrh/pdf/h990014b.pdf.
339
[7] Flinck A, Gottfridsson B. Experiences with iohexol and iodixanol during cardioangiography in an unselected patient population. Int J Cardiol 2001;80:143.
An unusual electrocardiogram artifact: what is its source? Nischita K. Reddya, Ramanna Merlab, Nonko D. Pehlivanovc, Pankaj J. Pasrichac, David L. Wared, Yochai Birnbaumd,T a Department of Neurology, The University of Texas Medical Branch, Galveston, TX 77555-0553, USA Department of Internal Medicine, The University of Texas Medical Branch, Galveston, TX 77555-0553, USA c Division of Gastroenterology, The University of Texas Medical Branch, Galveston, TX 77555-0553, USA d Division of Cardiology, The University of Texas Medical Branch, Galveston, TX 77555-0553, USA Received 25 April 2005; accepted 25 May 2005
b
Abstract
A diabetic female presented with nausea and vomiting. Her electrocardiogram showed sinus rhythm with two artifactual spikes, not synchronized with the cardiac rhythm. The patient had an implanted gastric electrical stimulation system for treating her diabetic gastroparesis. Recent DC shock for ventricular fibrillation during coronary angiography caused malfunction of the gastric pacemaker. D 2005 Elsevier Inc. All rights reserved.
Keywords:
Electrocardiogram; Artifactual spikes; Gastric electrical stimulation system (GES); Diabetic gastroparesis; Diabetis mellitus
1. Case A 52-year-old white female with severe diabetic gastroparesis and coronary artery disease requiring bypass grafting several years before presentation presented with nausea and vomiting. Fig. 1 shows her admission electrocardiogram (ECG). How should one interpret the artifact? Three years ago, a gastric electrical stimulation (GES) system (Enterra Therapy System, Medtronic, Minneapolis, MN; Fig. 2) was implanted to treat the patient’s nausea and vomiting from gastroparesis. During a cardiac catheterization performed a year before she presented to us, the patient received an external DC shock for ventricular fibrillation that occurred with intracoronary contrast injection. Following this, her symptoms of gastroparesis recurred. After interrogation, attempts at reprogramming the GES device failed. An evaluation by the manufacturer indicated that the DC shock had damaged the device’s battery and electrodes. The device was replaced, and the patient’s symptoms improved quickly. Three months later, the patient underwent coronary angiography for suspected myocardial ischemia, developed
T Corresponding author. Tel.: +1 409 772 2794; fax: +1 409 772 4982. E-mail address: [email protected] (Y. Birnbaum). 0022-0736/$ – see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2005.05.009
again ventricular fibrillation on intracoronary contrast injection, and received external DC shock. Her nausea and vomiting recurred after the procedure. Evaluation of the device showed that, although the generator continued to pace (creating the ECG artifact), one of the electrodes produced no electrical output, and its impedance could not be assessed. Reprogramming the body of the system as the positive pole and the remaining functional electrode as the negative pole produced no symptomatic improvement, and the system was eventually turned off. The patient currently awaits placement of another GES system. 2. Discussion A GES system stimulates the stomach musculature via 2 leads connected to a pulse generator. The leads may be implanted laparoscopically, and the pulse generator is placed in a subcutaneous pocket created in the abdominal wall. Adverse events reported with GES implantation have included device infections, device migration, stomach wall perforation, other postsurgical complications such as pulmonary embolism, aspiration pneumonia, and volvulus around the wires [1,6]. To our knowledge, this is the first report of GES malfunction caused by DC shock (PubMed and MEDLINE search; keywords: GES, cardioversion, gastroparesis, and pacer malfunction). Because GES is
338
N.K. Reddy et al. / Journal of Electrocardiology 38 (2005) 337–339
Fig. 1. ECG showing sinus rhythm with nonspecific ST-T changes and QT-interval prolongation. Two artifactual spikes occur approximately 11.5 times per minute and are not associated with the QRS complexes.
being used more often to treat refractory diabetic gastroparesis [1- 4], it would not be surprising if more such events occur in these patients whose incidence of coronary events and cardiac arrhythmias is high. Obviously, we recommend evaluating GES devices after any DC shock, which unlike cardiac pacemakers, are not protected with filtered feed through. However, the more problematic and complex management difficulties may arise from device-device interaction in GES patients who may
also need an implantable cardioverter/defibrillator. An implantable cardioverter/defibrillator might misinterpret GES pacing stimuli as a stable rhythm and not sense— and thus not treat—ventricular tachycardia or fibrillation. This potential problem must be considered in any diabetic patient before GES device implantation. The GES device is configured to stimulate the stomach wall approximately 12 times a minute (with recurring on and off cycles of 0.1 and 5 seconds, respectively) [1,5,6] and with default voltages of 1 to 4 V. This is apparent in this patient’s admission ECG, where the large GES pacing artifacts are occurring approximately 11.5 times each minute, with an amplitude of 2.5 mV. These stimuli are not synchronized with the cardiac cycle and in theory could induce ventricular fibrillation by pacing during the vulnerable period of myocardial repolarization. However, this would require not only bad timing, but also a sufficiently large pacing impulse delivered on the epicardium. There have been no previous reports of such an occurrence. It is very unlikely that GES caused this patient’s ventricular fibrillation, given the context in which the arrhythmia episodes occurred (immediately after intracoronary contrast injection) [7].
References
Fig. 2. Abdominal x-ray showing the GES generator and its leads, sternotomy wires and clips placed at the time of coronary bypass surgery, and a nasogastric tube.
[1] Lin Z, Forster J, Sarosiek I, McCallum RW. Treatment of diabetic gastroparesis by high-frequency gastric electrical stimulation. Diabetes Care 2004;27(5):1071. [2] Lin Z, Forster J, Sarosiek I, McCallum RW. Effect of high-frequency gastric electrical stimulation on gastric myoelectric activity in gastroparetic patients. Neurogastroenterol Motil 2004;16(2):205. [3] McCallum RW, Chen JD, Lin Z, Schirmer BD, Williams RD, Ross RA. Gastric pacing improves emptying and symptoms in patients with gastroparesis. Gastroenterology 1998;114(3):456. [4] Parkman HP, Hasler WL, Fisher RS. American Gastroenterological Association technical review on the diagnosis and treatment of gastroparesis. Gastroenterology 2004;127:1592.
N.K. Reddy et al. / Journal of Electrocardiology 38 (2005) 337–339 [5] Clinical Policy Bulletins, number: 0678, Gastric pacing/gastric electrical stimulation. http://www.aetna.com/cpb/data/CPBA0678.html. [6] Medtronic Enterra therapy system. H990014 — Summary of safety and probable benefit. http://www.fda.gov/cdrh/pdf/h990014b.pdf.
339
[7] Flinck A, Gottfridsson B. Experiences with iohexol and iodixanol during cardioangiography in an unselected patient population. Int J Cardiol 2001;80:143.