**4. Potential problems and disadvantages of OPCAB**

In general, the disadvantage of OPCAB is associated with surgical technique. Despite advances in surgical instruments, exposure of the posterior wall could be potentially difficult, especially in a patient with poor ventricular function or when the surgeon has not had adequate training in OPCAB. Inadequate exposure of the target results in fewer number of distal anastomoses and incomplete revascularization. Table 2 summaries poor candidates for OPCAB.


Table 2. The patients that the benefit least from OPCAB

#### **4.1 Myocardial protection**

Postoperative cardiac enzyme release is lower after OPCAB than after on-pump CABG. (Van Dijk et al., 2001) However, in a patient in cardiogenic shock with a failing heart, placement on the CPB is unavoidable to prevent further end organ damage, and the role of OPCAB is limited because of hemodynamic instability. If the patient is experiencing global ischemia, pump failure and unstable hemodynamics, OPCAB should not be performed.

Current Trend of Off-Pump Coronary Artery Bypass Grafting 57

2006). One of the risk factors for emergent conversion is ischemic mitral regurgitation. Preexisting ischemic mitral regurgitation may be accelerated during OPCAB due to

Cardiac motions during anastomosis are a major disturbance to the surgeon, and the OPCAB has a prominent learning curve. There is a direct correlation between the number of cases the surgeon has performed and the incidence of postoperative complications and graft patency. The surgeon with limited experience in OPCAB may produce a significant number of cardiac complications (Brown et al., 2001). Extensive training in performing OPCAB is

Graft patency after OPCAB may be related to the surgeon's skill level. A previous study by Khan showed a decreased 3-months-graft patency rate in the OPCAB group compared to that in the on-pump group (Khan et al., 2004). However, the article was criticized because of the lack of the surgeon's adequate OPCAB experiences, lack of postoperative antiplatelet therapy with clopidogrel, and failure to use a suction device for stabilization of the heart (Dewey et al., 2004). A recent randomized trial by Puskas (Puskas et al., 2009), and the European study (Widimsky et al., 2004) independently confirmed similar 1-year graft

Recent advances in surgical instruments and technique allows surgeons to perform OPCAB

Except for patient undergoing redo CABG, hemodynamically compromised patients, and patient with poor target vessels, OPCAB can be performed by an experienced surgeon

OPCAB contributes to shortening the length of stay and promotes an early recovery.

Although there is a steep learning curve for OPCAB techniques, OPCAB provides a favorable or at least equivalent postoperative outcome compared to on-pump CABG, with minimal contraindications. OPCAB will significantly reduce the risk of CPB-related complications. These benefits of OPCAB are more significant in high-risk patients, and there

Abu-Omar Y, Taggart DP. (2009) The present status of off-pump coronary artery bypass

OPCAB for left main disease and multivessel revascularization is no longer a

OPCAB may expand the indications of CABG to patients with higher risks.

Table 3. Summary of the advantages and disadvantages of OPCAB

grafting. *Eur J Cardiothorac Surg*. Vol. 36, No. 2, 312-321.

displacement of the heart during anastomosis and due to distal ischemia.

**4.7 Training** 

**4.8 Graft patency** 

**5. Conclusion** 

contraindication.

**6. References** 

without increasing risks.

safely.

necessary to improve patient outcomes.

patency rate between OPCAB and on-pump CABG.

OPCAB requires a significant intensive training period.

is a possibility to expand the indication of CABG.

These patients need immediate placement on CPB to reestablish systemic circulation. Hemodynamic instability may occur during the positioning of the OPCAB especially doing anastomosis to the posterior wall of the heart. If pharmacological support is not adequate, IABP is helpful to maintain hemodynamic stability during OPCAB (Vohra & Dimitri, 2006). In patients with poor ventricular function, IAPB placement prior to surgery is recommended.

#### **4.2 Redo cardiac surgery**

Redo surgery requires extensive dissection of the scar tissue. Structural injury during redosternotomy will result in a high mortality and morbidity (Gillinov et al., 1999). Decompression of the heart by CPB is recommended for redo surgery (Hirose & Amano 2005).

#### **4.3 Multivessel disease**

In the early era of OPCAB, revascularization of the posterolateral wall was challenging. However, after improvement of the coronary stabilizer, anastomoses to the posterolateral vessels are no longer a contraindication (Hirose et al., 2003, Song et al. 2003). Similarly, with left main disease, is no longer a contraindication for OPCAB (Hirose, 2004). In case of left main disease, revascularization of the left anterior descending artery prior to the posterolateral branches is essential. IABP may be helpful to stabilize hemodynamics, while anastomoses, especially in a patient with poor ventricular function and left main disease.

#### **4.4 Poor ventricular function**

Although mutilvessel disease is no longer contraindication for OPCAB, incomplete revascularization has been observed more often in OPCAB than on-pump CABG. A large heart with poor ventricular function is difficult to manipulate and to expose the target vessel. Heart displacement without decompression of the heart is challenging in these patients with poor ventricular function and distended left ventricle.

#### **4.5 Small and calcified target**

The reasons for incomplete revascularization could be the quality of the target vessel, as an example a small, calcified, or intramyocardial coronary artery. Bypass to these small coronary arteries and/or calcified arteries is challenging, even under on-pump cardiac arrest. Tedious endarterectomy for calcified vessels should be performed under CPB. Extensive dissection of intramyocardial coronary artery under a beating heart carries risk of ventricular rupture and should be performed with a decompressed heart under CPB. Incomplete revascularization will negatively affect the patient long-term outcome (Scott et al., 2000, Synnergre et al., 2008). A hybrid procedure involving OPCAB and percutaneous intervention could be an option in these difficult OPCAB patients.

#### **4.6 Emergent conversion to on-pump**

In palatines with hemodynamic instability during anastomosis, emergent conversion to onpump CABG is necessary. Conversion to on-pump surgery requires emergent arterial and venous cannulation, which may need to be done while CPR is in progress due to sudden ventricular arrhythmia or cardiac arrest. Emergent conversion from OPCAB to on-pump carries a ten-fold higher risk of operative mortality than elective OPCAB (Tabata et al., 2006). One of the risk factors for emergent conversion is ischemic mitral regurgitation. Preexisting ischemic mitral regurgitation may be accelerated during OPCAB due to displacement of the heart during anastomosis and due to distal ischemia.

### **4.7 Training**

56 Front Lines of Thoracic Surgery

These patients need immediate placement on CPB to reestablish systemic circulation. Hemodynamic instability may occur during the positioning of the OPCAB especially doing anastomosis to the posterior wall of the heart. If pharmacological support is not adequate, IABP is helpful to maintain hemodynamic stability during OPCAB (Vohra & Dimitri, 2006). In patients with poor ventricular function, IAPB placement prior to surgery is

Redo surgery requires extensive dissection of the scar tissue. Structural injury during redosternotomy will result in a high mortality and morbidity (Gillinov et al., 1999). Decompression of the heart by CPB is recommended for redo surgery (Hirose & Amano

In the early era of OPCAB, revascularization of the posterolateral wall was challenging. However, after improvement of the coronary stabilizer, anastomoses to the posterolateral vessels are no longer a contraindication (Hirose et al., 2003, Song et al. 2003). Similarly, with left main disease, is no longer a contraindication for OPCAB (Hirose, 2004). In case of left main disease, revascularization of the left anterior descending artery prior to the posterolateral branches is essential. IABP may be helpful to stabilize hemodynamics, while anastomoses, especially in a patient with poor ventricular function and left main disease.

Although mutilvessel disease is no longer contraindication for OPCAB, incomplete revascularization has been observed more often in OPCAB than on-pump CABG. A large heart with poor ventricular function is difficult to manipulate and to expose the target vessel. Heart displacement without decompression of the heart is challenging in these

The reasons for incomplete revascularization could be the quality of the target vessel, as an example a small, calcified, or intramyocardial coronary artery. Bypass to these small coronary arteries and/or calcified arteries is challenging, even under on-pump cardiac arrest. Tedious endarterectomy for calcified vessels should be performed under CPB. Extensive dissection of intramyocardial coronary artery under a beating heart carries risk of ventricular rupture and should be performed with a decompressed heart under CPB. Incomplete revascularization will negatively affect the patient long-term outcome (Scott et al., 2000, Synnergre et al., 2008). A hybrid procedure involving OPCAB and percutaneous

In palatines with hemodynamic instability during anastomosis, emergent conversion to onpump CABG is necessary. Conversion to on-pump surgery requires emergent arterial and venous cannulation, which may need to be done while CPR is in progress due to sudden ventricular arrhythmia or cardiac arrest. Emergent conversion from OPCAB to on-pump carries a ten-fold higher risk of operative mortality than elective OPCAB (Tabata et al.,

patients with poor ventricular function and distended left ventricle.

intervention could be an option in these difficult OPCAB patients.

recommended.

2005).

**4.2 Redo cardiac surgery** 

**4.3 Multivessel disease** 

**4.4 Poor ventricular function** 

**4.5 Small and calcified target** 

**4.6 Emergent conversion to on-pump** 

Cardiac motions during anastomosis are a major disturbance to the surgeon, and the OPCAB has a prominent learning curve. There is a direct correlation between the number of cases the surgeon has performed and the incidence of postoperative complications and graft patency. The surgeon with limited experience in OPCAB may produce a significant number of cardiac complications (Brown et al., 2001). Extensive training in performing OPCAB is necessary to improve patient outcomes.
