Ann Thorac Surg 2005;79:723-725
© 2005 The Society of Thoracic Surgeons
How to do it
A Simple Method of Triggering Balloon Counterpulsation Accurately During Off-Pump Coronary Artery Bypass Surgery
Takayuki Ono, MDa,*,
Teiji Asakura, MDa,
Takeki Ohashi, MDa,
Nagara Ono, MDb
a Department of Cardiovascular Surgery, Heart Centre, Nagoya Tokushukai General Hospital, Aichi, Japan
b Department of Anesthesiology, Heart Centre, Nagoya Tokushukai General Hospital, Aichi, Japan
Accepted for publication November 21, 2003.
* Address reprint requests to Dr Ono, Department of Cardiovascular Surgery, Heart Centre, Nagoya Tokushukai General Hospital, 2-28-1 Kozoji, Kasugai, Aichi 487-0013, Japan;
takohno{at}hotmail.com
 |
Abstract
|
|---|
With increasing experience, off-pump coronary artery bypass grafting for high-risk patients can be performed safely. However, in patients who need intraaortic balloon counterpulsation support, mistriggering of intraaortic balloon counterpulsation during mobilization of the heart can induce unstable hemodynamic conditions. My colleagues and I have developed a simple method of detecting the trigger signal accurately: an epicardial pacemaker wire is placed close to the apex of the left ventricle, and 1 precordial V lead is disconnected and then linked to the epicardial pacemaker wire. This method provides an excellent detection of R-wave potentials in any position of the heart throughout an entire off-pump coronary artery bypass grafting procedure.
|
Introduction
|
|---|
With sophisticated surgical techniques and experienced anesthetic management, off-pump coronary artery bypass grafting (OPCABG) can be performed safely and is indicated for high-risk patients who require preoperative insertion of intraaortic balloon counterpulsation (IABP), such as those with unstable angina, critical left main trunk stenosis, and left ventricular (LV) dysfunction [1, 2]. However, during the OPCABG procedure, mobilization of the heart frequently causes mistriggering or no triggering of IABP, which can induce unstable hemodynamic conditions such as ventricular arrhythmias and decreased blood pressure. Therefore, an accurate triggering of IABP during mobilization of the heart is crucial for the safety and success of OPCABG. My colleagues and I have developed a simple method for detecting R-wave potentials accurately by using an epicardial pacemaker wire placed in the LV.
|
Technique
|
|---|
All OPCABG procedures were performed by full sternotomy. During mobilization of the heart, an epicardial pacemaker wire was placed close to the apex of the LV (Fig 1A). One precordial V lead was disconnected and then linked to the epicardial pacemaker wire. This simple modification of the Einthoven's triangle electrocardiogram (ECG) configuration with repositioning a precordial V electrode to an epicardial pacemaker wire provided an exact and continuous detection of R-wave potentials in any position of the heart throughout an entire OPCABG procedure (Fig 1B). Although our first-choice location for epicardial pacemaker wire placement is close to the apex of the LV, in a few patients the R-wave potentials could be lower than those of the P or T waves. In such cases, the right ventricle is an alternative site. With this simple method, OPCABG could be performed safely on patients with stable hemodynamic conditions.
View larger version (71K):
[in this window]
[in a new window]
|
Fig 1. During mobilization of the heart, an epicardial pacemaker wire placed to the left ventricle is connected to the V5 electrocardiogram electrode (A). This simple method provides an accurate and continuous detection of R waves (arrows) thorough the off-pump coronary artery bypass surgery grafting procedure (B).
|
|
|
Comment
|
|---|
This direct trigger method provides excellent timing of IABP during all stages of the OPCABG procedure and solves a potentially dangerous problem associated with the use of IABP during OPCABG. This method is simple and requires no expensive equipment.
Until now, IABPs have usually been synchronized with either the arterial blood pressure waveform or the patient's ECG. Possible causes of mistriggering or no triggering of IABP during the OPCABG procedure include the following: (1) mobilization and stabilization of the heart is likely to induce a decrease in arterial pressure, which makes it difficult to synchronize IABP by detecting the arterial blood pressure waveform, or (2) mobilization of the heart from its anatomic position leads to a change of potentials and configuration of both the P and R waves traced by a conventional method (Fig 2). This change leads to an inaccurate detection of the ECG potentials. One way to synchronize the IABP is by a pacemaker potential. However, patients with hemodynamic instability have often tachycardia, which makes this method less useful, and even the pacemaker potential cannot be attained accurately during the OPCABG procedure. Use of a pacing pulmonary artery catheter for triggering IABP might be an alternative method, and its usefulness remains to be studied.
View larger version (24K):
[in this window]
[in a new window]
|
Fig 2. During mobilization and stabilization of the heart, the potentials and configuration of the P and R waves are continuously changing. Note that the potentials of the P wave (arrows) are often higher than those of R wave, in which case intraaortic balloon counterpulsation is mistakenly triggered by the P wave.
|
|
With experienced anesthetic management, most patients seem to tolerate mistriggering of IABP well during the OPCABG procedure. Therefore, at first, we used this method for the highest-risk patients, such as those with acute myocardial infarction and cardiogenic shock, in whom intraoperative stable hemodynamic conditions largely depended on effective IABP support and in whom mistriggering or no triggering of IABP would have cause critical hemodynamic conditions. Without accurate triggering of IABP, these patients might be at high risk for converting to cardiopulmonary bypass, and OPCABG would be contraindicated [3, 4]. After completion of the OPCABG procedure, we usually returned to the standard triggering of IABP by detecting the arterial blood pressure waveform or by using precordial leads. However, in patients with the highest risk, postoperative use of the epicardial lead for synchronizing IABP was also helpful because their blood pressure and ECG potentials were frequently low. Furthermore, in patients with bradycardia, the combined techniques of atrial pacing and our direct trigger method would provide even greater cardiac support. Therefore, our method would have the most beneficial effect among these highest-risk patients.
With increasing experience with our method, we found that intraoperative anesthetic management for the patients who required IABP support was, ironically, easier, as compared with those who did not require IABP support. Anesthetic management with effective IABP is easier because (1) the amount of inotropic and vasopressor agents can be reduced and because (2) minimal volume infusion will suffice to maintain blood pressure and cardiac output. Therefore, we recommend this method for all patients with IABP who undergo OPCABG.
|
References
|
|---|
- Babatasi G, Massetti M, Bruno PG, et al. Pre-operative balloon counterpulsation, and off-pump coronary surgery for high-risk patients. Cardiovasc Surg. 2003;11:145–148[Medline]
- Magee MJ, Coombs LP, Peterson ED, et al. Patient selection and current practice strategy for off-pump coronary artery bypass surgery. Circulation. 2003;108(Suppl 2):II9–14
- Mishra M, Shrivastava S, Dhar A, et al. A prospective evaluation of hemodynamic instability during off-pump coronary artery bypass surgery. J Cardiothorac Vasc Anesth. 2003;17:452–458[Medline]
- Hochman JS, Buller CE, Sleeper LA, et al. Cardiogenic shock complicating acute myocardial infarction: etiologies, management and outcome—overall findings of the SHOCK Trial Registry. J Am Coll Cardiol. 2000;36:1063–1070[Abstract/Free Full Text]
This article has been cited by other articles:
|
|
|
|
 
T. Ono, T. Ohashi, T. Asakura, N. Ono, M. Ono, N. Motomura, and S. Takamoto
Impact of Diabetic Retinopathy on Cardiac Outcome After Coronary Artery Bypass Graft Surgery: Prospective Observational Study
Ann. Thorac. Surg.,
February 1, 2006;
81(2):
608 - 612.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
