Intracoronary Shunt Prevents Ischemia in Off-Pump Coronary Artery Bypass Surgery

doi:10.1016/j.athoracsur.2008.08.032

The Annals of Thoracic Surgery

Volume 87, Issue 1, January 2009, Pages 54-60

https://doi.org/10.1016/j.athoracsur.2008.08.032 Get rights and content

Background

The purpose of this study was to evaluate the role of intracoronary shunt during off-pump coronary artery bypass surgery.

Methods

Fifty-six patients undergoing off-pump coronary artery bypass using the left internal mammary artery to bypass the left anterior descending coronary artery were randomly assigned to have the bypass performed with intracoronary shunt or by occlusive snaring. Ischemia during grafting was monitored by tissue Doppler. Hemodynamic status and indicators of ischemia were monitored, and on-table and postoperative angiography were performed.

Results

In patients with retrograde filling of the left anterior descending coronary artery, ischemia did not develop, but occlusion of antegradely perfused vessels caused ischemia in 26 of 33 patients. Ischemia was reversed in 14 of 16 shunted patients, and in 3 of 17 nonshunted cases (p = 0.004). Angiography showed a trend toward improved on-table angiographic results in shunted patients. After 3 months, graft patency was 100%, but 1 patient treated without shunt required reintervention and 15 patients had new angiographic lesions, equally distributed between shunted and nonshunted patients.

Conclusions

Intracoronary shunt prevents ischemia during grafting of the left anterior descending coronary artery and provides satisfactory immediate- and short-term graft patency.

Section snippets

Material and Methods

Patients scheduled for OPCABG were randomly assigned to two groups. In the no-shunt group, left internal mammary artery (LIMA) grafting to the LAD was performed with proximal occlusion. In the shunt group, an intracoronary shunt was utilized. Transesophageal ultrasonography with tissue Doppler was used to detect ischemia in the interventricular septum. Potential damage from the shunt or from snaring was monitored by clinical follow-up, monitoring of cardiac enzymes, electrocardiography (ECG),

Results

Twenty-seven patients were randomly assigned to shunt and 29 to no shunt. There were no differences between groups with regard to demographics or risk factors, except for more smokers in the shunt group (Table 1). In 3 patients, shunt insertion was unsuccessful, and the graft was performed as in the no-shunt group. Two shunts had a diameter of 1.25 mm, 14 had a diameter of 1.50 mm, 7 had a diameter of 1.75 mm, and 1 had a diameter of 2.00 mm. All no-shunt patients were treated without shunt.

Comment

Technical improvements have made OPCABG a more attractive option for coronary revascularization than when described by Kolesov [22] in the 1960s. The OPCABG surgeon still occasionally faces myocardial ischemia and hemodynamic collapse during surgery. An intracoronary shunt may prevent such events and the need for emergency initiation of CPB [2, 23] and help the surgeon to perform a better anastomosis. It is possible, however, that a shunt may denude the endothelium and cause vessel damage,

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Citation Excerpt :
Target vessels must be isolated and blood flow controlled to allow sufficient visualization for sewing. Intracoronary shunts are used to circumvent the transient occlusion of the coronary allowing distal coronary perfusion (Fig 1).4,5 As experience increases, surgeons who perform OPCAB often liberalize the criteria for patients who may benefit from OPCAB.6
Modern treatment of cardiovascular disease requires a patient-centered approach. With several technological advances, the options for treatment must be carefully weighed and novel approaches tested for safety and efficacy. In this article, we outline some of the new approaches available to cardiothoracic surgeons for the treatment of cardiovascular diseases, including off-pump coronary artery bypass grafting, transcatheter valve replacement, and hybrid and robotic technology. We discuss current evidence and controversies and highlight the challenges that we face in training surgeons in an environment of ever-evolving surgical techniques.
Clinical validation of coronary artery flow through an intracoronary shunt during off-pump coronary artery bypass grafting
2014, Journal of Thoracic and Cardiovascular Surgery
Intracoronary shunts have been developed for a bloodless field and preserved forward flow preventing ischemia during off-pump coronary artery bypass (OPCAB) surgery. However, reports directly measuring the forward flow through the shunt in clinical settings are lacking.
Using a 7.5-MHz Doppler probe, we investigated the coronary flow through a 1.5-mm shunt inserted into the left anterior descending artery (LAD) for anastomosis with the internal thoracic artery during OPCAB in 30 consecutive patients. The following Doppler flow parameters were obtained before and after shunting: peak velocity, mean velocity, time-velocity integral, and flow.
No patients developed significant electrocardiographic changes and the peak value of postoperative myocardial band of creatine kinase was 17 ± 16 IU/L. All Doppler flow parameters of the LAD decreased significantly after shunting; peal velocity: 71.3 ± 34.6 cm/second to 54.5 ± 25.3 cm/second (−24% ± 27%), mean velocity: 33.3 ± 18.3 cm/second to 26.3 ± 14.0 cm/second (−21% ± 23%), and time-velocity integral: 28.7 ± 12.1 cm to 19.0 ± 7.1 cm (−28% ± 14%), and flow: 38.7 ± 16.8 mL/minute to 25.0 ± 9.5 mL/minute (−31% ± 13%) (P < .01).
The LAD flow is preserved at least 50% through a 1.5-mm intracoronary shunt, although the flow pattern was attenuated, during OPCAB anastomosis. The Doppler evaluation of the coronary artery flow before and after shunting is useful to justify the protective use of the shunt on myocardial perfusion during OPCAB.
Anesthetic management of robotically assisted totally endoscopic coronary artery bypass surgery (TECAB)
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Left ventricular segmental wall motion abnormalities also occur during target-vessel occlusion in beating-heart TECAB. Selective use of a shunt for open, off-pump CABG, when myocardial ischemia is detected, protects against infarction.38,39 In TECAB, use of the same may resolve ischemia detected by either regional wall motion abnormalities on TEE or ST-segment changes on ECG.
Meta-analysis of organ damage after conversion from off-pump coronary artery bypass procedures
2011, Annals of Thoracic Surgery
Citation Excerpt :
Most of the included studies mention an “ischemia-hypotension” phenomenon as the main reason for emergency conversion. The importance of myocardial protection in OPCAB surgery including the use of coronary shunts [35] and selection of the ideal grafting sequence [36] has been highlighted before. However, above all the formation of a secure, leak-proof anastomosis is the most important factor and this is surgeon dependent [37].
The relative efficacy of off-pump and on-pump coronary revascularization is uncertain. A complication of off-pump surgery which is rarely considered is intraoperative conversion to cardiopulmonary bypass. Consequently, meta-analysis was performed of studies comparing morbidity after converted and nonconverted off-pump coronary revascularization. There were significant increases in the likelihood of stroke, myocardial injury, bleeding, renal failure, wound infection, intraaortic balloon pump requirement, transfusion, and respiratory and gastrointestinal complications after conversion. The underlying mechanisms need to be urgently elucidated. Prevention and treatment protocols for conversion warrant serious consideration and the risk of conversion may need to be discussed when obtaining informed patient consent.
Conversion and safety in off-pump coronary artery bypass: A system failure that needs re-emphasis
2011, Annals of Thoracic Surgery
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Their association with conversion, and any role they may have in its prevention, has not been formally investigated. However, in a recent randomized study, Bergsland and colleagues [45] demonstrated that use of intracoronary shunts could significantly reverse the ischemia in LAD vessels with anterograde filling that were being proximally occluded during grafting. Reduction in postoperative troponin I release [46], reduced echocardiographic evidence of acute ischemia, and improved graft patency [47] have also been reported with intracoronary shunts.
Institution of cardiopulmonary bypass after commencement of “off-pump” coronary artery bypass surgery is known as conversion. This may be an emergency or elective process. The phenomenon of conversion, although widely reported, remains under-emphasized. Emergency conversion may lead to poorer patient outcomes and therefore warrants serious consideration. The rate of conversion may influence the results of randomized controlled trials, and be considered a surrogate performance indicator of surgical competence in off-pump coronary artery bypass. Several causes and predictors of conversion are reported in published literature. This article aims to examine the phenomenon of conversion in off-pump coronary artery bypass and proposes a framework for its prevention.
Reply
2010, Annals of Thoracic Surgery

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Original articleAdult cardiacIntracoronary Shunt Prevents Ischemia in Off-Pump Coronary Artery Bypass Surgery

Background

Methods

Results

Conclusions

Section snippets

Material and Methods

Results

Comment

J Vasc Surg

Eur J Vasc Endovasc Surg

J Vasc Surg

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

J Surg Res

Ann Thorac Surg

Ann Thorac Surg

Br J Anaesth

J Am Soc Echocardiogr

Ann Thorac Surg

J Thorac Cardiovasc Surg

J Cardiothorac Vasc Anesth

Ann Thorac Surg

Ann Thorac Surg

Ann Thorac Surg

Original article
Adult cardiac
Intracoronary Shunt Prevents Ischemia in Off-Pump Coronary Artery Bypass Surgery