Temporary Cardiac Pacing



Temporary Cardiac Pacing


Seth T. Dahlberg



Temporary cardiac pacing may be urgently required for the treatment of cardiac conduction and rhythm disturbances commonly seen in patients treated in the intensive care unit (ICU). Therefore, ICU personnel should be familiar with the indications and techniques for initiating and maintaining temporary cardiac pacing as well as the possible complications of this procedure. Recommendations for training in the performance of transvenous pacing have been published by a Task Force of the American College of Physicians, American Heart Association and American College of Cardiology [1]. Competence in the performance of transvenous pacing also requires the operator to have training in central venous access (see Chapter 2) and hemodynamic monitoring (see Chapter 4).


Indications for Temporary Cardiac Pacing

As outlined in Table 5-1, temporary pacing is indicated in the diagnosis and management of a number of serious rhythm and conduction disturbances [2,3].


Bradyarrhythmias

The most common indication for temporary pacing in the ICU setting is a hemodynamically significant or symptomatic brady-arrhythmia such as sinus bradycardia or high-grade atrioventricular (AV) block.

Sinus bradycardia and AV block are commonly seen in patients with acute coronary syndromes, hyperkalemia, myxedema, or increased intracranial pressure. Infectious processes such as endocarditis or Lyme disease [4] may impair AV conduction. Bradyarrhythmias also result from treatment or intoxication with digitalis, antiarrhythmic, beta-blocker, or calcium channel blocker medications and may also result from exaggerated vasovagal reactions to ICU procedures such as suctioning of the tracheobronchial tree in the intubated patient. Bradycardia-dependent ventricular tachycardia may occur in association with ischemic heart disease.


Tachyarrhythmias

Temporary cardiac pacing has been used in both prevention and termination of supraventricular and ventricular tachyarrhythmias [5]. Atrial pacing is often effective in terminating atrial flutter and paroxysmal nodal supraventricular tachycardia [6]. Atrial pacing in the ICU setting is most frequently performed when temporary epicardial electrodes have been placed during cardiac surgery. A critical pacing rate (usually 125% to 135% of the flutter rate) and pacing duration (usually about 10 seconds) are important in the successful conversion of atrial flutter to sinus rhythm [7,8]. This method is often effective in patients with classic atrial flutter; however, it is typically ineffective for atypical or type II atrial flutter (rate 400 beats per minute, P waves upright in the inferior leads).

In some clinical situations pacing termination of atrial flutter may be more attractive than synchronized cardioversion, which requires sedation with its attendant risks. Pacing termination is the treatment of choice for atrial flutter in patients with epicardial atrial wires in place after cardiac surgery. It may be preferred as the means to convert atrial flutter in patients on digoxin and those with sick sinus syndrome, as these groups often demonstrate prolonged sinus pauses after DC cardioversion [9].

Temporary pacing has proved lifesaving in preventing paroxysmal polymorphic ventricular tachycardia in patients with prolonged QT intervals (torsades de pointes), particularly when secondary to drugs. Temporary cardiac pacing is the treatment of choice to stabilize the patient while a type I antiarrhythmic agent exacerbating ventricular irritability is metabolized [10]. In this situation, the pacing rate is set to provide a mild tachycardia. The effectiveness of cardiac pacing probably relates to decreasing the dispersion of refractoriness of the ventricular myocardium (shortening the QT interval).

Temporary ventricular pacing is also frequently successful in terminating ventricular tachycardia [11]. If ventricular tachycardia must be terminated urgently, cardioversion is mandated. However, in less urgent situations, conversion of ventricular tachycardia via rapid ventricular pacing may be useful. The success of this technique depends on the setting in which ventricular tachycardia occurs as well as the type of pacing used (rapid overdrive pacing or programmed extrastimulation). Programmed stimulation techniques are usually effective in terminating ventricular tachycardia in a patient with remote myocardial infarction or in the absence of heart disease. This technique is less effective when ventricular tachycardia complicates acute myocardial infarction or cardiomyopathy. Rapid ventricular pacing is most successful in terminating ventricular tachycardia when the ventricle can be “captured” (asynchronous pacing for 5 to 10 beats at a rate of 50 beats per minute greater than that of the underlying tachycardia). Extreme caution is advised, as it may be accompanied by acceleration of ventricular tachycardias in more than 40% of patients; a cardiac defibrillator should be immediately available at the bedside.


Diagnosis of Rapid Rhythms

Temporary atrial pacing electrodes allow accurate diagnosis of tachyarrhythmias when the morphology of the P wave and its relation to the QRS complexes cannot be determined from the
surface electrocardiogram (ECG) [12,13]. A recording of the atrial electrogram is particularly helpful in a rapid, regular, narrow-complex tachycardia in which the differential diagnosis includes atrial flutter with rapid ventricular response, and AV nodal reentrant or other supraventricular tachycardia. This technique is also useful to distinguish wide-complex tachycardias in which the differential diagnosis includes supraventricular tachycardia with aberrant conduction, sinus tachycardia with bundle branch block, and ventricular tachycardia.








TABLE 5-1. Indications for Acute (Temporary) Cardiac Pacing






Conduction disturbances
   Symptomatic persistent third-degree AV block with inferior myocardial infarction
   Third-degree AV block, new bifascicular block (e.g., right bundle branch block and left anterior hemiblock, left bundle branch block, first-degree AV block), or alternating left and right bundle branch block complicating acute anterior myocardial infarction
   Symptomatic idiopathic third-degree AV block, or high-degree AV block
Rate disturbances
   Hemodynamically significant or symptomatic sinus bradycardia
   Bradycardia-dependent ventricular tachycardia
   AV dissociation with inadequate cardiac output
   Polymorphic ventricular tachycardia with long QT interval (torsades de pointes)
   Recurrent ventricular tachycardia unresponsive to medical therapy Av, atrioventricular.
Av, atrioventricular.

To record an atrial ECG, the limb leads are connected in the standard fashion and a precordial lead (usually V1) is connected to the proximal electrode of the atrial pacing catheter or to an epicardial atrial electrode. A rhythm strip is run at a rapid paper speed, simultaneously demonstrating surface ECG limb leads as well as the atrial electrogram obtained via lead V1. This rhythm strip should reveal the conduction pattern between atria and ventricles as antegrade, simultaneous, retrograde, or dissociated.


Acute Myocardial Infarction

Temporary pacing may be used therapeutically or prophylactically in acute myocardial infarction. Recommendations for temporary cardiac pacing have been provided by a Task Force of the American College of Cardiology and the American Heart Association (Table 5-2) [14]. Bradyarrhythmias unresponsive to medical treatment that result in hemodynamic compromise require urgent treatment. Patients with anterior infarction and bifascicular block or Mobitz type II second-degree AV block, while hemodynamically stable, may require a temporary pacemaker, as they are at risk for sudden development of complete heart block with an unstable escape rhythm.

Prophylactic temporary cardiac pacing has aroused considerable debate for the role it may play in complicated anterior wall myocardial infarction [15]. Thrombolytic therapy or percutaneous coronary intervention, when indicated, should take precedence over placement of prophylactic cardiac pacing, as prophylactic pacing has not been shown to improve mortality. Transthoracic (transcutaneous) cardiac pacing is safe and usually effective [16, 17, 18 and 19] and would be a reasonable alternative to prophylactic transvenous cardiac pacing, particularly soon after thrombolytic therapy has been administered.

When right ventricular involvement complicates inferior myocardial infarction, cardiac output may be very sensitive to ventricular preload. Because coordinated atrial transport may be required for maintenance of effective stroke volume, AV sequential pacing is frequently the pacing modality of choice in patients with right ventricular infarction [20,21].


Equipment Available for Temporary Pacing

Several methods of temporary pacing are currently available for use in the ICU. Transvenous pacing of the right ventricle or right atrium with a pacing catheter or modified pulmonary artery catheter is the most widely used technique; intraesophageal, transcutaneous, and epicardial pacing are also available.


Transvenous Pacing Catheters

Some of the many transvenous pacing catheters available for use in the critical care setting are illustrated in Figure 5-1. Pacing catheters range in size from 4 French (Fr) (1.2 mm) to 7 Fr (2.1 mm). In urgent situations, or where fluoroscopy is unavailable, a flow-directed flexible balloon-tipped catheter (Fig. 5-1, top) may be placed in the right ventricle using ECG guidance. After advancing the catheter into the right ventricle, the balloon can be deflated and the catheter tip advanced to the right ventricular apex. While the balloon-tipped catheter may avoid the need for fluoroscopy, placement may be ineffective in the setting of low blood flow during cardiac arrest or in the presence of severe tricuspid regurgitation. Stiff catheters (Fig. 5-1, middle) are easier to manipulate but require insertion under fluoroscopic guidance.

A flexible J-shaped catheter (Fig. 5-1, bottom), designed for temporary atrial pacing, is also available [22]. This lead is positioned by “hooking” it in the right atrial appendage under fluoroscopic guidance, providing stable contact with the atrial endocardium. Either the subclavian or internal jugular venous approach may be used.

A multilumen pulmonary artery catheter is available with a right ventricular lumen. Placement of a small (2.4 Fr) bipolar pacing lead through the right ventricular lumen allows intracardiac pressure monitoring and pacing through a single catheter [23]. Details on its use and insertion are described in Chapter 4.


Esophageal Electrode

An esophageal “pill” electrode allows atrial pacing and recording of atrial depolarizations without requiring central venous cannulation. As mentioned, detecting atrial depolarization aids in the diagnosis of tachyarrhythmias. Esophageal pacing has also been used to terminate supraventricular tachycardia and atrial flutter [24]. Because the electrode can be uncomfortable and may not give consistent, stable capture, the esophageal electrode is typically limited to short-term use for diagnosis of arrhythmias in pediatric patients.









TABLE 5-2. ACC/AHA Recommendations for Treatment of Atrioventricular and Intraventricular Conduction Disturbances During STEMI
















































































































































































































































































































































































































Intraventricular Conduction AV Conduction
Normal 1st-Degree AV Block Mobitz I 2nd-Degree AV Block Mobitz II 2nd-Degree AV Block
AMI Non-AMI AMI Non-AMI AMI Non-AMI
Normal Action Class Action Class Action Class Action Class Action Class Action Class Action Class
OB 1 OB 1 OB 1 OB 2B OB 2A OB 3 OB 3
A 3 A 3 A 3 A* 3 A 3 A 3 A 3
TC 3 TC 2B TC 2B TC 1 TC 1 TC 1 TC 1
TV 3 TV 3 TV 3 TV 3 TV 3 TV 2A TV 2A
Old or New Fascicular Block (LAFB or LPFB) OB 1 OB 2B OB 2B OB 2B OB 2B OB 3 OB 3
A 3 A 3 A 3 A* 3 A 3 A 3 A 3
TC 2B TC 1 TC 2A TC 1 TC 1 TC 1 TC 1
TV 3 TV 3 TV 3 TV 3 TV 3 TV 2A TV 2B
Old BBB OB 1 OB 3 OB 3 OB 3 OB 3 OB 3 OB 3
A 3 A 3 A 3 A* 3 A 3 A 3 A 3
TC 2B TC 1 TC 1 TC 1 TC 1 TC 1 TC 1
TV 3 TV 2B TV 2B TV 2B TV 2B TV 2A TV 2A
New BBB OB 3 OB 3 OB 3 OB 3 OB 3 OB 3 OB 3
A 3 A 3 A 3 A* 3 A 3 A 3 A 3
TC 1 TC 1 TC 1 TC 1 TC 1 TC 2B TC 2B
TV 2B TV 2A TV 2A TV 2A TV 2A TV 1 TV 1
Fascicular Block + RBBB OB 3 OB 3 OB 3 OB 3 OB 3 OB 3 OB 3
A 3 A 3 A 3 A* 3 A 3 A 3 A 3
TC 1 TC 1 TC 1 TC 1 TC 1 TC 2B TC 2B
TV 2B TV 2A TV 2A TV 2A TV 2A TV 1 TV 1
Alternating Left and Right BBB OB 3 OB 3 OB 3 OB 3 OB 3 OB 3 OB 3
A 3 A 3 A 3 A* 3 A 3 A 3 A 3
TC 2B TC 2B TC 2B TC 2B TC 2B TC 2B TC 2B
TV 1 TV 1 TV 1 TV 1 TV 1 TV 1 TV 1
This table is designed to summarize the atrioventricular (column headings) and intraventricular (row headings) conduction disturbances that may occur during acute anterior or nonanterior STEMI, the possible treatment options, and the indications for each possible therapeutic option.
A, atropine; AMI, anterior myocardial infarction; AV, atrioventricular; BBB, bundle-branch block; LAFB, left anterior fascicular block; LPFB, left posterior fascicular block; MI, myocardial infarction; non-AMI, nonanterior myocardial infarction; OB, observe; RBBB, right bundle-branch block; STEMI, ST elevation myocardial infarction; TC, transcutaneous pacing; TV, temporary transvenous pacing.
Action: There are four possible actions, or therapeutic options, listed and classified for each bradyarrhythmia or conduction problem:
1. Observe: continued ECG monitoring, no further action planned.
2. A, and A*: atropine administered at 0.6 to 1.0 mg IV every 5 min to up to 0.04 mg/kg. In general, because the increase in sinus rate with atropine is unpredictable, this is to be avoided unless there is symptomatic bradycardia that will likely respond to a vagolytic agent, such as sinus bradycardia or Mobitz I, as denoted by the asterisk, above.
3. TC: application of transcutaneous pads and standby transcutaneous pacing with no further progression to transvenous pacing imminently planned.
4. TV: temporary transvenous pacing. It is assumed, but not specified in the table, that at the discretion of the clinician, transcutaneous pads will be applied and standby transcutaneous pacing will be in effect as the patient is transferred to the fluoroscopy unit for temporary transvenous pacing.
Class: Each possible therapeutic option is further classified according to ACC/AHA criteria as Class 1: indicated, 2A: probably indicated, 2B: possibly indicated, and 3: not indicated.
Level of Evidence: This table was developed from published observational case reports and case series, published summaries, not meta-analyses, of these data; and expert opinion, largely from the prereperfusion era. There are no published randomized trials comparing different strategies of managing conduction disturbances after STEMI. Thus, the level of evidence for the recommendations in this table is C.
How to Use the Table: Example: 54-year-old man is admitted with an anterior STEMI and a narrow QRS on admission. On day 1, he develops a right bundle-branch block (RBBB), with a PR interval of 0.28 seconds.
1. RBBB is an intraventricular conduction disturbance, so look at row “New BBB.”
2. Find the column for “First-Degree AV Block.”
3. Find the “Action” and “Class” cells at the convergence.
4. Note that “Observe” and “Atropine” are class 3, not indicated; transcutaneous pacing (TC) is class 1. Temporary transvenous pacing (TV) is class 2B. Copyright 2004 American College of Cardiology Foundation. [From Antman EM, Anbe DT, Armstrong PW, et al.: ACC/AHA guidelines for the management of patients with STelevation myocardial infarction—executive summary. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to revise the 1999 guidelines for the management of patients with acute myocardial infarction). J Am Coll Cardiol 44:671–719, 2004, with permission.]

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Aug 27, 2016 | Posted by in CRITICAL CARE | Comments Off on Temporary Cardiac Pacing

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