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Pacemaker spikes misleading the diagnosis of ventricular fibrillation
Resuscitation 66 (2005) 241–243
Case report
Pacemaker spikes misleading the diagnosis of ventricular fibrillation夽 Robert F. Bonvini, Edoardo Camenzind ∗ Cardiology Department, University Hospital, Geneva, Switzerland Received 19 October 2004; received in revised form 23 December 2004; accepted 28 January 2005
Abstract Pacemakers are used more and more in modern cardiology, because of the increasing age of patients and the increasing number of cases of congestive heart failure treated with biventricular stimulation. Twelve lead ECG traces of electro-stimulated patients normally can be interpreted correctly, but in emergency circumstances where only a three lead ECG trace is available (i.e. the usual monitoring setting in the pre-hospital arena or intensive care unit) recognition of the underlying baseline rhythm may be difficult. The case described illustrates how differentiation between true asystole and fine ventricular fibrillation in the presence of some confounding elements (e.g. pacemaker meditated spikes) can be challenging for the physician and life-threatening for the patient. Therefore, after selecting the best diagnostic ECG trace, direct current defibrillation should be used in the presence of a persistent but uncertain cardiac rhythm, even if it may be thought to be asystole or pulse-less electrical activity. © 2005 Published by Elsevier Ireland Ltd. Keywords: Pacemaker; Direct current defibrillation; Ventricular fibrillation
1. Introduction
2. Case report
In the emergency setting, the presence of ventricular pacing can make the recognition of some life-threatening cardiac arrhythmias or diseases more difficult, even in the presence of a 12 lead ECG trace (e.g. acute myocardial infarction in a patient stimulated with a pacemaker). In the out-of-hospital or intensive care unit (ICU) setting, urgent clinical decisions, in particular concerning arrhythmias, are often made according to a 3 lead ECG monitor tracing, which makes the interpretation of the underlying cardiac rhythm even more challenging. This is true both for standard and the automatic external defibrillators (AED) which are equipped with sophisticated filtering and diagnostic algorithms [1,2]. We report a case of pulseless electrical activity (PEA) in a patient monitored with an ICU monitor, in which life-saving direct current (DC) defibrillation was delayed significantly, because of erroneous underlying rhythm interpretation.
A 52-year-old woman with a history of aortic valve replacement due to post-rheumatic regurgitation and with a pacemaker implanted because of complete post-operative atrio-ventricular block 3 years earlier, was admitted with septic shock (Staphylococcus aureus) secondary to prosthetic valve infection. Transthoracic and transesophageal echocardiography confirmed the diagnosis of endocarditis involving the aortic prosthesis and the right ventricular pacemaker electrode. Despite aggressive antibiotic therapy, the patient developed cardiac failure requiring cardiac surgery. The aortic root was replaced by a composite-graft valve (Bentall intervention), the pacemaker system (stimulator and electrodes) was completely removed and new epicardial leads with an abdominal stimulator were implanted. The ensuing weeks were characterized by several complications (e.g. pulmonary infection, kidney failure, haemorrhagic stroke) and finally, the patient developed apparent PEA requiring cardio-pulmonary resuscitation (CPR). Due to the presence of the pacemaker spikes on the ICU monitor, and no detectable invasive blood pressure (Fig. 1), the patient was managed with a PEA protocol. After 20 min of CPR, DC defibrillation was attempted, promptly restoring a blood
夽 A Spanish translated version of the Abstract and Keywords of this article
appears as Appendix at 10.1016/j.resuscitation.2005.01.017. ∗ Corresponding author. Tel.: +41 22 372 7200; fax: +41 22 372 7229. E-mail address: [email protected] (E. Camenzind). 0300-9572/$ – see front matter © 2005 Published by Elsevier Ireland Ltd. doi:10.1016/j.resuscitation.2005.01.017
242
R.F. Bonvini, E. Camenzind / Resuscitation 66 (2005) 241–243
Fig. 1. Intensive care unit monitor showing the transition to VF with persistent electrical ventricular PM spikes (arrowheads) with sudden invasive blood pressure collapse (arrow).
pressure. This suggested an underlying fine wave ventricular fibrillation (VF), interspersed with high amplitude epicardial pacemaker spikes. The printout of the monitor tracing (Fig. 2) confirmed the diagnosis.
3. Discussion Cardiac pacemakers are used more and more in modern cardiology for a widening spectrum of indications in an increasingly aging population (i.e. bi-ventricular stimulation for heart failure treatment). Pacemaker patients are at high risk of cardiovascular events. Sudden cardiac death secondary to VF (>1000/year in Switzerland) in pacemaker patients (>20,000 in Switzerland) potentially is becoming a frequent issue. Therefore, physicians and ambulance crews should be aware of the potential pitfalls linked to CPR and rhythm analysis in these patients. Bipolar electrodes, for atrial or ventricular stimulation, offer some advantages compared to unipolar stimulation, including a reduced amplitude of the pacemaker spikes on the
ECG tracing [3]. However, as with our patient who had epicardial electrodes, unipolar stimulation sometimes has to be preferred. In critical situations (e.g. cardiac arrest), obtaining a 12 lead ECG is time consuming and therefore resuscitation decisions are usually based on a 2 or 3 lead ECG tracing from the AED or the ICU monitor. However, in these settings, the detection of fine underlying rhythm anomalies can be very difficult. Guideline protocols require a check on the most informative ECG trace before making a decision. In our case the switch to alternative ECG evaluation was omitted, because the attending clinician had no doubt in interpreting the rhythm as PEA, because of the presence of pacemaker activity with no blood pressure (Fig. 1) in an acidotic, hypoxaemic patient. Therefore the patient was resuscitated according to the PEA protocol. The guidelines do not recommend DC defibrillation in a flat-line rhythm suggesting asystole, because the chances of missing very fine wave VF are rare, [1,4,5] but this case illustrates the importance of the accurate understanding of the situation and correct application of resuscitation protocols,
Fig. 2. Intensive care unit monitor showing direct current defibrillation shock (double-head arrow) followed by PM mediated atrial (small arrowhead) and ventricular (arrowhead) electrical spikes with following restoration of the blood pressure (arrow).
R.F. Bonvini, E. Camenzind / Resuscitation 66 (2005) 241–243
especially in challenging settings where the cardiac rhythm interpretation has be based on a single ECG monitor tracing. In fact, only retrospective analysis of the print out of the ECG trace from the ICU monitor, permitted clear identification of the VF fine waves underlying the regular ventricular pacemaker spikes (Fig. 2). In conclusion, if the interpretation of the underlying electrical activity on the monitor is unclear, the search for a better diagnostic tracing by switching to alternative ECG evaluations should be attempted. If the trace remains unclear, DC defibrillation may be life saving and should be attempted rapidly, especially in the presence of cardiac rhythm confounding elements such as pacemaker mediated spikes. It should be noted that an AED may also not deliver a shock in the presence of pacemaker activity confirming that not only humans but also pre-programmed algorithms may be mistaken in these challenging settings [2].
243
References [1] American Heart Association in collaboration with the International Liaison Committee on Resuscitation (ILCOR). International guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care—a consensus on science. Resuscitation 2000;46:103– 252. [2] Monsieurs KG, Conraads VM, Goethals MP, Snoeck JP, Bossaert LL. Semi-automatic external defibrillation and implanted cardiac pacemakers: understanding the interactions during resuscitation. Resuscitation 1995;30(2):127–31. [3] Baker Jr RG, Falkenberg EN. Bipolar versus unipolar issues in DDD pacing. Pacing Clin Electrophysiol 1984;7(6 Pt 2):1178– 82. [4] Cummins RO, Austin Jr D. The frequency of ‘occult’ ventricular fibrillation masquerading as a flat line in prehospital cardiac arrest. Ann Emerg Med 1988;17(8):813–7. [5] Martin DR, Gavin T, Bianco J, et al. Initial countershock in the treatment of asystole. Resuscitation 1993;26(1):63–8.
Case report
Pacemaker spikes misleading the diagnosis of ventricular fibrillation夽 Robert F. Bonvini, Edoardo Camenzind ∗ Cardiology Department, University Hospital, Geneva, Switzerland Received 19 October 2004; received in revised form 23 December 2004; accepted 28 January 2005
Abstract Pacemakers are used more and more in modern cardiology, because of the increasing age of patients and the increasing number of cases of congestive heart failure treated with biventricular stimulation. Twelve lead ECG traces of electro-stimulated patients normally can be interpreted correctly, but in emergency circumstances where only a three lead ECG trace is available (i.e. the usual monitoring setting in the pre-hospital arena or intensive care unit) recognition of the underlying baseline rhythm may be difficult. The case described illustrates how differentiation between true asystole and fine ventricular fibrillation in the presence of some confounding elements (e.g. pacemaker meditated spikes) can be challenging for the physician and life-threatening for the patient. Therefore, after selecting the best diagnostic ECG trace, direct current defibrillation should be used in the presence of a persistent but uncertain cardiac rhythm, even if it may be thought to be asystole or pulse-less electrical activity. © 2005 Published by Elsevier Ireland Ltd. Keywords: Pacemaker; Direct current defibrillation; Ventricular fibrillation
1. Introduction
2. Case report
In the emergency setting, the presence of ventricular pacing can make the recognition of some life-threatening cardiac arrhythmias or diseases more difficult, even in the presence of a 12 lead ECG trace (e.g. acute myocardial infarction in a patient stimulated with a pacemaker). In the out-of-hospital or intensive care unit (ICU) setting, urgent clinical decisions, in particular concerning arrhythmias, are often made according to a 3 lead ECG monitor tracing, which makes the interpretation of the underlying cardiac rhythm even more challenging. This is true both for standard and the automatic external defibrillators (AED) which are equipped with sophisticated filtering and diagnostic algorithms [1,2]. We report a case of pulseless electrical activity (PEA) in a patient monitored with an ICU monitor, in which life-saving direct current (DC) defibrillation was delayed significantly, because of erroneous underlying rhythm interpretation.
A 52-year-old woman with a history of aortic valve replacement due to post-rheumatic regurgitation and with a pacemaker implanted because of complete post-operative atrio-ventricular block 3 years earlier, was admitted with septic shock (Staphylococcus aureus) secondary to prosthetic valve infection. Transthoracic and transesophageal echocardiography confirmed the diagnosis of endocarditis involving the aortic prosthesis and the right ventricular pacemaker electrode. Despite aggressive antibiotic therapy, the patient developed cardiac failure requiring cardiac surgery. The aortic root was replaced by a composite-graft valve (Bentall intervention), the pacemaker system (stimulator and electrodes) was completely removed and new epicardial leads with an abdominal stimulator were implanted. The ensuing weeks were characterized by several complications (e.g. pulmonary infection, kidney failure, haemorrhagic stroke) and finally, the patient developed apparent PEA requiring cardio-pulmonary resuscitation (CPR). Due to the presence of the pacemaker spikes on the ICU monitor, and no detectable invasive blood pressure (Fig. 1), the patient was managed with a PEA protocol. After 20 min of CPR, DC defibrillation was attempted, promptly restoring a blood
夽 A Spanish translated version of the Abstract and Keywords of this article
appears as Appendix at 10.1016/j.resuscitation.2005.01.017. ∗ Corresponding author. Tel.: +41 22 372 7200; fax: +41 22 372 7229. E-mail address: [email protected] (E. Camenzind). 0300-9572/$ – see front matter © 2005 Published by Elsevier Ireland Ltd. doi:10.1016/j.resuscitation.2005.01.017
242
R.F. Bonvini, E. Camenzind / Resuscitation 66 (2005) 241–243
Fig. 1. Intensive care unit monitor showing the transition to VF with persistent electrical ventricular PM spikes (arrowheads) with sudden invasive blood pressure collapse (arrow).
pressure. This suggested an underlying fine wave ventricular fibrillation (VF), interspersed with high amplitude epicardial pacemaker spikes. The printout of the monitor tracing (Fig. 2) confirmed the diagnosis.
3. Discussion Cardiac pacemakers are used more and more in modern cardiology for a widening spectrum of indications in an increasingly aging population (i.e. bi-ventricular stimulation for heart failure treatment). Pacemaker patients are at high risk of cardiovascular events. Sudden cardiac death secondary to VF (>1000/year in Switzerland) in pacemaker patients (>20,000 in Switzerland) potentially is becoming a frequent issue. Therefore, physicians and ambulance crews should be aware of the potential pitfalls linked to CPR and rhythm analysis in these patients. Bipolar electrodes, for atrial or ventricular stimulation, offer some advantages compared to unipolar stimulation, including a reduced amplitude of the pacemaker spikes on the
ECG tracing [3]. However, as with our patient who had epicardial electrodes, unipolar stimulation sometimes has to be preferred. In critical situations (e.g. cardiac arrest), obtaining a 12 lead ECG is time consuming and therefore resuscitation decisions are usually based on a 2 or 3 lead ECG tracing from the AED or the ICU monitor. However, in these settings, the detection of fine underlying rhythm anomalies can be very difficult. Guideline protocols require a check on the most informative ECG trace before making a decision. In our case the switch to alternative ECG evaluation was omitted, because the attending clinician had no doubt in interpreting the rhythm as PEA, because of the presence of pacemaker activity with no blood pressure (Fig. 1) in an acidotic, hypoxaemic patient. Therefore the patient was resuscitated according to the PEA protocol. The guidelines do not recommend DC defibrillation in a flat-line rhythm suggesting asystole, because the chances of missing very fine wave VF are rare, [1,4,5] but this case illustrates the importance of the accurate understanding of the situation and correct application of resuscitation protocols,
Fig. 2. Intensive care unit monitor showing direct current defibrillation shock (double-head arrow) followed by PM mediated atrial (small arrowhead) and ventricular (arrowhead) electrical spikes with following restoration of the blood pressure (arrow).
R.F. Bonvini, E. Camenzind / Resuscitation 66 (2005) 241–243
especially in challenging settings where the cardiac rhythm interpretation has be based on a single ECG monitor tracing. In fact, only retrospective analysis of the print out of the ECG trace from the ICU monitor, permitted clear identification of the VF fine waves underlying the regular ventricular pacemaker spikes (Fig. 2). In conclusion, if the interpretation of the underlying electrical activity on the monitor is unclear, the search for a better diagnostic tracing by switching to alternative ECG evaluations should be attempted. If the trace remains unclear, DC defibrillation may be life saving and should be attempted rapidly, especially in the presence of cardiac rhythm confounding elements such as pacemaker mediated spikes. It should be noted that an AED may also not deliver a shock in the presence of pacemaker activity confirming that not only humans but also pre-programmed algorithms may be mistaken in these challenging settings [2].
243
References [1] American Heart Association in collaboration with the International Liaison Committee on Resuscitation (ILCOR). International guidelines 2000 for cardiopulmonary resuscitation and emergency cardiovascular care—a consensus on science. Resuscitation 2000;46:103– 252. [2] Monsieurs KG, Conraads VM, Goethals MP, Snoeck JP, Bossaert LL. Semi-automatic external defibrillation and implanted cardiac pacemakers: understanding the interactions during resuscitation. Resuscitation 1995;30(2):127–31. [3] Baker Jr RG, Falkenberg EN. Bipolar versus unipolar issues in DDD pacing. Pacing Clin Electrophysiol 1984;7(6 Pt 2):1178– 82. [4] Cummins RO, Austin Jr D. The frequency of ‘occult’ ventricular fibrillation masquerading as a flat line in prehospital cardiac arrest. Ann Emerg Med 1988;17(8):813–7. [5] Martin DR, Gavin T, Bianco J, et al. Initial countershock in the treatment of asystole. Resuscitation 1993;26(1):63–8.