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CE Article

Atrial Electrograms After Cardiac Surgery: Survey of Clinical Practice

Corresponding author: Jane N. Miller, RN, MS, CNS, CCRN, 5403 Paulson Cir, Boise, ID 83704 (e-mail: mrsjanemiller{at}yahoo.com).

	Abstract

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Background The American Heart Association 2004 practice standards for electrocardiographic monitoring in hospitals recommend that nurses record an atrial electrogram whenever tachycardia of unknown origin develops in a patient after cardiac surgery. An atrial electrogram can be recorded from atrial epicardial pacemaker wires left in place following surgery. Because surgical practices have changed in recent years (earlier extubation and mobilization, shorter stays), it is unclear whether epicardial wires are still readily available to record an atrial electrogram.

Objective To determine current practices in recording atrial electrograms.

Methods A convenience sample of nurses subscribing to the American Association of Critical-Care Nurses electronic newsletter was surveyed.

Results The sample comprised 247 nurses who worked in an intensive or progressive care unit in which patients were treated after cardiac surgery. Respondents were from 41 states and 139 cities. Nearly 90% of respondents had more than 5 years’ nursing experience; 75% had more than 5 years’ experience caring for patients after cardiac surgery. Although 92.1% of respondents reported that atrial epicardial pacing wires were left in place after cardiac surgery, only 10.2% recorded atrial electrograms often, and more than 30% had never recorded one. Analysis of written comments indicated that atrial electrograms are rarely used. Among nurses who had recorded an atrial electrogram, recordings were made about equally with a standard 12-lead electrocardiography machine and a bedside cardiac monitor.

Conclusions Although atrial epicardial pacemaker wires are often available for recording atrial electrograms, few nurses use apical epicardial wires for atrial electrograms to analyze arrhythmias.

Notice to CE enrollees:A closed-book, multiple-choice examination following this article tests your understanding of the following objectives: Describe the rationale for using atrial electrograms in the hospital setting after cardiac surgery. Recognize a recommended means of assessing tachycardias of unknown origin after cardiac surgery according to American Heart Association standards. Understand the role of critical care nurses in assessing, recording, and analyzing arrhythmias after cardiac surgery. To read this article and take the CE test online, visit www.ajcconline.org and click "CE Articles in This Issue." No CE test fee for AACN members.

Skin surface acts as a passive opposing force (ie, a resistor) in the active conduction of cardiac electrical energy and creates a loss or impedance of the current of electricity across the conductor. The resultant reduction in voltage across the skin from the cardiac impulse per ampere of current flow can help explain the smaller, sometimes undetectable P waves of standard 12-lead ECGs compared with the amplified P waves on atrial electrograms. With electrograms, the proximity of the recording wires to the atrial impulses greatly enhances atrial waveforms.

Postoperative arrhythmias, especially those of supraventricular origin, are a frequent complication after cardiac surgery.¹ Because of continuous cardiac monitoring and frequent assessments of patients, nurses are generally the first healthcare personnel to detect abnormal rhythms and often are the first to intervene. Bedside monitors and standard 12-lead ECGs display the heart’s electrical activity from leads placed on the chest wall and torso. Compared with conventional surface ECGs, atrial electrograms offer a more definitive means of assessing and interpreting rhythm abnormalities.

The tracings of cardiac electrical activity in atrial electrograms are made through epicardial pacing electrodes in direct contact with the surface of the heart.^2,3 The temporary pacing wires are brought externally through cutaneous tissues of the anterior part of the chest wall or the upper quadrants of the abdominal wall. Typically, atrial wires emerge on the right side and ventricular wires on the left side. However, placement of epicardial or external leads may vary from institution to institution or may depend on a surgeon’s preferences.^2,4

Atrial electrograms can be recorded by using a bedside monitor or a standard 12-lead ECG machine^5–8 (Figure 1). If a bedside monitor is used, the ideal practice is to print out a rhythm strip that has 2 or more channels so that findings from a surface ECG lead can be shown along with the atrial electrogram (Figure 2). The amplified P wave with atrial electrograms is extremely important in diagnosing arrhythmias that have indiscernible P waves on standard ECG recordings, such as in ventricular tachycardia or atrioventricular blocks. Moreover, atrial electrograms are useful for differentiating supraventricular arrhythmias such as atrial fibrillation or flutter and sinus, junctional, or atrial tachycardias. Such supraventricular arrhythmias may be especially difficult to detect on standard ECGs when a patient has a wide QRS complex due to a bundle branch block. Because atrial electrograms minimize the size of the QRS complex in bundle branch block while maximizing atrial waveforms, the arrhythmia mechanism can usually be readily determined. Atrial electrograms can be obtained quickly by nurses with minimal disturbance to patients and can clarify ambiguous rhythms to prevent misdiagnosis and incorrect treatment.

View larger version (33K): [in this window] [in a new window]   Figure 1 Setup for recording an atrial electrogram by using a bedside monitor and a double alligator clip to connect atrial pacer wire to C (chest or V) lead.

View larger version (20K): [in this window] [in a new window]   Figure 2 Atrial electrogram recorded with the bedside monitor. Atrial wire is attached to the chest (V) lead wire and, therefore, displayed in lead V (top tracing). Routine lead II is displayed on the bottom tracing. The patient is in sinus tachycardia with frequent premature beats with a wide QRS complex. In the atrial electrogram recording, P waves are large spikes that can be seen even when buried in the wide QRS complexes in lead II. The pattern of dissociated P waves "marching through" the wide QRS complexes indicates that the premature beats are ventricular rather than supraventricular with aberration.

The recently published American Heart Association practice standards for ECG monitoring in hospitals⁹ recommend that nurses record an atrial electrogram whenever a tachycardia of unknown origin develops in a patient after cardiac surgery. Because surgical practices have changed in recent years, with earlier extubation and mobilization of patients and shorter stays in the intensive care unit (ICU), it is unclear whether epicardial wires are still readily available to record an atrial electrogram. Therefore, the purposes of our survey were to determine (1) how often and how long atrial wires are left in place after cardiac surgery, (2) whether nurses are recording atrial electrograms, and (3) what equipment (standard 12-lead ECG machine or bedside cardiac monitor) is being used to obtain atrial electrograms. In addition, an open-ended question was included to explore other issues related to the recording of atrial electrograms that might be important.

Atrial arrhythmias continue to be a common complication after cardiac surgery, with an occurrence of up to 65% within the first 3 postoperative days.

 

	Methods

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Study Design
A national survey was conducted to determine current practices for recording atrial electrograms after cardiac surgery. A descriptive research design was used to survey a convenience sample of nurses who received the electronic newsletter Critical Care Newsline from the American Association of Critical-Care Nurses (AACN) during the month of November 2005.

Sample
The electronic newsletter is sent to approximately 50 000 AACN members who have e-mail addresses within AACN’s database and who consent to receive e-mail from AACN. The recipient population is 97% registered nurses and is in alignment with the overall AACN member demographics and areas of specialization.¹⁰ Periodically scheduled AACN surveys of the newsletter recipients continue to validate alignment of the recipients with AACN member characteristics.

Questionnaire
The survey used "logic" progression through a SurveyMonkey tool to exclude nurses who did not provide care for patients after cardiac surgery and, later in the survey, to exclude nurses who did not work with epicardial wires. Unless a respondent was excluded from the survey, all questions were required to be answered in order to complete and submit the survey. Survey respondents were allowed to provide qualitative responses at the end of the survey to elaborate on specific practices related to atrial electrography at their institution. The survey included a total of 13 questions: 8 on the characteristics of the respondent and 5 on the respondent’s practice related to recording atrial electrograms (Table 1).

	Results

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Sample Characteristics
A total of 263 AACN members responded to the atrial electrogram survey. Through the logic progression described earlier, the actual survey included only the 247 respondents who worked in an intensive care or progressive care unit with postoperative cardiac surgery patients and who completed the survey. Nurses who did not work with epicardial pacemaker wires were later excluded from the final survey questions; the final sample size was 227 respondents. A total of 80.7% of respondents were 30 to 55 years old, nearly 90% had more than 5 years of nursing experience, and 75% had more than 5 years of experience providing care to postoperative cardiac surgery patients (Table 2).

Atrial Electrogram Practice
Most respondents (92.1%) reported that at least one surgeon at their facility retained atrial epicardial wires after cardiac surgery (Table 3). The most common length of time atrial epicardial wires were left in place was 1 to 3 days (46.7%). However, it was not uncommon for the wires to be in place until the patient was discharged from the hospital (25.9%).

More than 30% of the respondents reported that they had never recorded an atrial electrogram. A total of 40.1% of respondents recorded atrial electrograms infrequently (every 10 patients or less often). Only 10.2% recorded atrial electrograms often (every patient or every few patients). Of the nurses who had recorded atrial electrograms, the recordings were made about equally with a standard 12-lead ECG machine and with a bedside cardiac monitor.

Qualitative responses were easily grouped into 3 categories: (1) responses that represented positive experiences and practices related to atrial electrograms, (2) questions and educational needs of nurses related to atrial electrogram practice, and (3) perceived barriers to use of atrial electrograms. Qualitative analysis of additional comments indicated that atrial electrograms were considered valuable for arrhythmia diagnosis but had been used more often in previous years. The nurses who reflected confidence in performing atrial electrograms were strong proponents of the practice; they described mutual collaboration with surgeons who supported the importance and value of atrial electrograms, education and mentoring programs related to atrial electrograms, and institutional interest. Other respondents stated that atrial electrograms had been largely abandoned in current practice, or delegated to nurse practitioners or physicians. Several respondents reflected physicians’ nonsupport for the practice.

Many nurses indicated an interest in learning to perform atrial electrography so that "it is second nature to us." Others commented on the lack of a standardized procedure at their institution. A few respondents mentioned a trend for surgeons to place ventricular, but not atrial, epicardial pacemaker wires in patients after coronary artery bypass grafting, a practice that precludes recording atrial electrograms for those patients.

	Discussion

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This survey was the first on the practice of recording atrial electrograms in postoperative cardiac surgery patients. Our findings indicate that most nurses (92.1% of nurses surveyed) work in settings where atrial epicardial pacemaker wires are left in place after cardiac surgery. More than 90% of respondents reported that the length of time that these wires are left in place is greater than 24 hours. However, only 10.2% of the nurses record atrial electrograms often, and 30.5% have never recorded one. Barriers to recording of atrial electrograms include perceived lack of physicians’ support for the practice, delegation of such recording from staff nurses to nurse practitioners or physicians, and lack of unit protocols and training. The survey results indicate that the use of atrial electrograms varies widely despite recommendations by the American Heart Association to use atrial electrograms postoperatively as an adjunct for arrhythmia diagnosis.

Limitations of the study include a possible selection bias of respondents. However, respondents represented a variety of postoperative cardiac settings across the United States, and their data were statistically similar to demographic data from nursing surveys.^10,11

Epicardial wires have been placed in cardiac surgery patients since the 1960s. Soon after that, the usefulness of atrial electrograms for therapeutic or diagnostic purposes grew substantially. In a study by Waldo et al,³ 81% of heart surgery patients had atrial epicardial wires placed that were used for diagnostic or therapeutic purposes. Compared with the results of that study, our findings indicate that an even higher proportion of atrial epicardial wires are available in current clinical practice.

Atrial arrhythmias continue to be a common complication after cardiac surgery, with an occurrence of up to 65% within the first 3 postoperative days.¹² Hogue et al¹ reported that atrial arrhythmias occur in more than 30% of patients hospitalized for coronary artery bypass grafting. The incidence is greater for valve surgery or for combined valve surgery and coronary artery bypass grafting.^12,13 Ventricular and junctional arrhythmias as well as atrioventricular node and sinus node blocks also may occur after cardiac surgery. Factors that place patients at higher risk for arrhythmias include advanced age; comorbid conditions of cardiac, pulmonary, or other origin; intraoperative or perioperative physiological factors; and genetic predisposition.¹² Postoperative arrhythmias can contribute to unstable hemodynamic conditions, thromboembolism, increased morbidity, and prolonged hospitalization.¹ Accurate diagnosis of the arrhythmia mechanism is essential to guide clinical decision making about the appropriate therapy.

Atrial electrograms are a useful tool with multiple indications.⁸ They can be valuable in the following circumstances:

• Atrial depolarization is not visible with surface ECG leads (bedside monitor or standard 12-lead ECG).
  
• The relationship between atrial and ventricular electrical activity is unclear.
  
• Wide QRS complex rhythms need to be defined (eg, distinguishing ventricular tachycardia from supraventricular tachycardia with a bundle branch block or aberrant conduction).
  
• Clarification of tachycardias with a narrow QRS complex is needed when the arrhythmia mechanism is unclear.
  

An alternative method to improve arrhythmia analysis that was investigated several years ago was not any less invasive, less cumbersome, or more efficient than the atrial electrogram. The esophageal pill electrode introduced by Arzbaecher¹⁴ produced well-defined P waves.^14–16 An advantage of the pill electrode was that its use was not restricted solely to postoperative cardiac surgery patients with epicardial pacemaker wires in place. However, the pill electrode did not gain acceptance in clinical practice and is no longer commercially available.

A major drawback of the pill electrode was that it was not advisable to have a postoperative patient in an unstable hemodynamic condition with an arrhythmia sit up and swallow a large pill electrode. Occasional artifacts and inconsistent placement of the electrode also were problems,^14,15 although troubleshooting was later addressed by Quaal et al.¹⁶ Major advantages of atrial electrograms are that they can be recorded without disturbing the patient and they are accurate and cost-efficient because they do not require purchase of additional electrodes or equipment.

Institutional use of atrial electrograms requires operator skill and knowledge of not only correct procedure but also safe practice and awareness of potential hazards. As with any invasive catheter or use of equipment that plugs into an electrical outlet, users must be cognizant of potential consequences and dangers. Use of correct and proper procedures for connections, insulation, and disconnections, as well as assurance that hospital safety and infection precaution requirements are met, will aid in preventing complications and hazardous situations. All information must be a part of departmental policy or procedure documents for atrial electrograms.

Education that includes knowledge of possible unexpected outcomes related to epicardial wires and use of atrial electrograms will prepare staff to be proactive and aware of potential emergencies. For instance, gloves must be worn when staff may come in contact with epicardial wires; it is imperative that aseptic technique be maintained and microshocks be prevented. When not securely attached to the temporary pacemaker generator, the bare metal tip of the epicardial wire that is not insulated must be covered in an insulating material according to unit policy. This will provide a shield against microshocks that can create risk for critical arrhythmias. Arrhythmias, infection, bleeding, or unstable hemodynamic conditions can occur with uses of epicardial wires.

Future Research
Future research on use of atrial electrograms in cardiac surgery patients is rich with possibilities. A literature review of atrial electrograms and nursing care yielded few articles and even fewer published research studies. Future studies should include research on optimal education and skills needed for atrial electrogram programs, effective standardized protocols, and effective physician-nurse collaboration for use of atrial electrograms. In addition, we need to determine which patients are most likely to benefit from atrial electrograms. Problems and troubleshooting associated with use of atrial electrograms also should be researched because such research would promote safety and confidence in nurses who teach and use atrial electrography.

Conclusions and Clinical Implications
Atrial epicardial pacemaker wires are often available for recording atrial electrograms in postoperative cardiac patients. However, few nurses use apical epicardial wires to obtain atrial electrograms for arrhythmia diagnosis, and some nurses have no experience recording atrial electrograms. Yet interest persists in understanding atrial electrograms, learning the skill, and interpreting the results. Clinical decision making based on atrial electrograms could improve patient care and affect morbidity, length of stay, and hospital costs. A number of excellent articles and resources are available to assist in initial education, skills, and safety needs.^3,6–9

Clinical decision making based on atrial electrograms could improve patient care and affect morbidity, length of stay, and hospital costs.

 

Education is needed on the diagnostic value of and the recording technique for atrial electrograms to comply with recently published evidence-based practice standards.⁹ Strategies to support endeavors to use atrial electrograms appropriately include the following:

• Development of institutional standards, protocols, and education for safe and effective use of atrial electrograms
  
• Documentation of nurses’ competencies to perform atrial electrography
  
• Resources and support to perform atrial electrography during emergent situations when patients have hemodynamic compromise due to unstable arrhythmias
  
• Collaboration with hospital administrators, nurse managers, and physicians to support, promote, and recognize safe and optimal patient care related to use of atrial electrograms
  
• Generation of awareness through poster presentations, education, word of mouth, and provision of role models to help nurses learn and improve their skills in atrial electrography
  

eLetters
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This article is followed by an AJCC Patient Care Page on page 360.

	REFERENCES

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2. Finkelmeier BA, O’Mara SR. Temporary pacing after cardiac surgery. Focus Crit Care. 1991;18:65–74.[Medline]
3. Waldo AL, Henthorn RW, Plumb VJ. Temporary epicardial wire electrodes in the diagnosis and treatment of arrhythmias after open heart surgery. Am J Surg. 1984;148:275–283.[Medline]
4. Waldo AL, MacLean WAH, Cooper TB, Kouchoukos N, Karp RB. Use of temporarily placed epicardial atrial wire electrodes for the diagnosis and treatment of cardiac arrhythmias following open-heart surgery. JThorac Cardiovasc Surg. 1978;76:500–505.[Abstract]
5. Dziadulewicz L, Lang R. The use of atrial electrograms in the diagnosis of supraventricular dysrhythmias. AACN Clin Issues. 1992;3:203–208.
6. Hutchinson ML. Correct procedures for performing atrial electrocardiograms (ECGs) using the 5-lead bedside cable and epicardial pacing wires. Crit Care Nurse. 2001;21(5):69–71.[Medline]
7. Sulzbach LM, Lansdowne LM. Temporary atrial pacing after cardiac surgery. Focus Crit Care. 1991;18:65–74.[Medline]
8. Preuss T, Wiegand DL. Atrial electrograms. In: Wiegand DJL, Carlson KK, eds. AACN Procedure Manual for Critical Care. 5th ed. St Louis, MO: Elsevier Saunders; 2005:296–303.
9. Drew BJ, Califf RM, Funk M, et al. Practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association scientific statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized Electrocardiology and the American Association of Critical-Care Nurses [published correction appears in Circulation. 2005;111(3):378]. Circulation. 2004;110(17):2721–2746.[Abstract/Free Full Text]
10. American Association of Critical-Care Nurses. Membership demographics. December 1, 2000. http://www.aacn.org/__88256508006b5202.nsf/0/fe550a5fba8aa7b9882569af005b4198?OpenDocument. Accessed April 11, 2007.
11. The registered nurse population. Preliminary findings: national sample survey of registered nurses. Department of Health and Human Services, Health Resources and Services Administration. March 2004. http://bhpr.hrsa.gov/healthworkforce/reports/rnpopulation/preliminaryfindings.htm. Accessed April 9, 2007.
12. Maisel WH, Rawn JD, Stevenson WG. Atrial fibrillation after cardiac surgery. Ann Intern Med. 2001;135:1061–1073.[Abstract/Free Full Text]
13. Andrews TC, Reimold SC, Berlin JA, et al. Prevention of supraventricular arrhythmias after coronary artery bypass surgery: a meta-analysis of randomized control trials. Circulation. 1999;84(suppl III):III236–III244.
14. Arzbaecher R. A pill electrode for the study of cardiac arrhythmias. Med Instrum. 1978;12(5):277–281.[Medline]
15. Brody DA, Copeland GD. The principles of esophageal electrocardiography. Am Heart J. 1959;57:3–18.[Medline]
16. Quaal SJ, Phillips B, Howery T, Jadvar H. The pill electrode: new technology as an adjunct to nursing assessment of patient arrhythmias. Prog Cardiovasc Nurs. 1989;4(1):10–17.[Medline]

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