© 2014 Wiley Periodicals, Inc.
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SURGICAL TECHNIQUE ___________________________________________________________
On Pump Evaluation of the Anastomotic Patency of In Situ Arterial Grafts Vasileios Tsiopoulos, M.D., Claudio Pragliola, M.D., Mario Gaudino, M.D., and Massimo Massetti, M.D. Dipartimento di Scienze Cardiovascolari, Unita` di Chirurgia del Cuore e dello Scompenso Cardiaco, Universita` Cattolica del Sacro Cuore, Policlinico Agostino Gemelli, Roma, Italy ABSTRACT We describe a variation of the standard intraoperative transit time flow evaluation that allows the assessment of the anastomotic patency of in situ arterial grafts before the release of the aortic cross clamp. The advantages of this technique are the immediate correction of technical imperfections and the evaluation of native competitive flow situations that may compromise long-term patency. doi: 10.1111/jocs.12315 (J
Card Surg 2014;29:487–489)
The advantages of routine intraoperative transit-time flow control (TTF) in coronary artery surgery have been clearly demonstrated.1 The analysis of the morphology of the flow curve in the grafts provides a reliable assessment of the technical accuracy of the anastomosis and may also predict the durability of the revascularization.2 Usually in cases using cardioplegia the TTF evaluation is performed at the end of the procedure under stable hemodynamic conditions after weaning the patients from the cardiopulmonary bypass. This strategy has two major disadvantages: (1) whenever it is necessary to revise an anastomosis the extracorporeal circulation has to be reestablished, the aorta recross-clamped and the cardioplegia reinfused; (2) TTF evaluation in these conditions is subject to the confounding effect of the interaction between native and graft flow that, in case of nonocclusive stenosis of the target vessel, can lead to inaccurate and misleading results. We propose a simple technical variation that enables an immediate evaluation of the anatomic patency of the anastomosis of in situ arterial grafts before the release of the aortic cross-clamp, allowing a prompt revision in case of malfunction and thus avoiding the confounding effects of native competitive flow.
Conflict of interest: The authors acknowledge no conflict of interest in the submission. Address for correspondence: Claudio Pragliola, M.D., Dipartimento di Scienze Cardiovascolari, Policlinico A. Gemelli, Largo Gemelli 8, 00168 Roma, Italy. Fax: þ39-06-3015-5881; e-mail: [email protected]
TECHNIQUE The principle behind this technique is the presence of residual anterograde flow in the native coronary artery. With the aorta cross-clamped the TTF probe is applied to the in situ graft immediatly after the completion of the anastomosis. The proximal grafted native coronary is gently snared as described for off-pump coronary artery bypass (OPCAB) surgery.3 In these conditions the flow curve recorded is driven directly by the heart lung machine and shows a sinusoid pattern determined by the roller pump (Fig. 1). With a mean systemic pressure of 65 to 70 mmHg, in absence of competitive flow from the native coronary artery, we consider acceptable a minimal flow of 15 mL/min mmHg2 into the distal edge of the anastomosis. After this evaluation the proximal snare on the native coronary artery is released and antegrade cardioplegic solution is infused into the aortic root at a controlled pressure of 100 mmHg. In presence of a nonocclusive stenosis of the target native vessel, this antegrade flow of cardioplegia competes with that of the graft; the result is a progressive reduction of the graft flow easily recordable with the TTF evaluation (Fig. 2). It must be noted that during the infusion of the cardioplegia the flow into the in situ graft rapidly declines to 0 mL/min and the sinusoidal curve partially or completely falls below this value indicating a flow reversal into the graft (Fig. 2, lower part). This pattern indicates the patency of the proximal edge of the anastomosis. The reduction of infusion in the aortic root leads to gradual reversal of this phenomenon with restoration of initial graft flow. In Y arterial grafts the probe is placed on the common branch and a delicate vessel clamp is alternatively
488
PRAGLIOLA, ET AL. TTF CONTROL OF IN SITU GRAFT
J CARD SURG 2014;29:487–489
Figure 1. In situ internal thoracic artery (ITA) to left anterior descending artery (LAD). In this patient the circulation was supported by a roller pump. Cardioplegia is off.
moved on the two branches of the Y. With these principles in mind the procedure can be adapted also to sequential grafts in order to check all the individual anastomosis. All patients undergoing myocardial revascularization with ‘‘in situ’’ arterial grafts had their anastomoses routinely checked since July 2011. In this period 4.4% of the 4141 anastomoses in 1414 patients were revised before and 0.2% after the release of the aortic crossclamp. Additionally four patients (0.4%) were submitted to an early postoperative coronary angiography and received a percutaneous coronary angioplasty of the native vessel for an anastomotic malfunction.
DISCUSSION This procedure was conceived to improve the anatomic patency of in situ arterial grafts. The evaluation is very fast and easy to perform, does not modify the standard operative technique, and can be completed in less than two minutes. It provides information regarding the anatomic patency of the anastomosis and allows immediate revision in case of suspected malfunction. Bidirectional flow can be checked by snaring the target coronary artery proximally and distally to the anastomosis and recording the flow alternatively releasing the snares. The same concept applies to
Figure 2. In situ ITA to the LAD. In the upper quadrant the cardioplegia is off. In the lower quadrant the flow of the cardioplegia into the native vessel competes with the flow into the graft.
J CARD SURG 2014;29:487–489
sequential grafts: the anastomoses can be checked one by one by placing several clamps along the conduit. The described method has the additional advantage of evaluating graft flow in the absence of competitive flow from the native vessel. This is of particular relevance in case of subocclusive target vessel stenosis: a situation where classical TTF evaluation can give doubtful and misleading results and even lead to unnecessary revision of the anastomosis. We are aware of the fact that other nontechnical factors such as the myocardial temperature, the composition and the temperature of the cardioplegia,4 and the extension and the resistence of the graft and coronary vascular bed5 may influence the flow at the anastomosis. To overcome this possible bias we have learned from experience that a minimal value of 15 mL/min is easily obtainable with an optimal anastomosis and is independent from nontechnical factors. In conclusion, our technique does not intend to replace the standard TTF evaluation performed at the end of the surgical procedure but it allows a simple and immediate evaluation of the anastomosis after its completion. The procedure has potential advantages in case of technical imperfection of the anastomosis and in native
PRAGLIOLA, ET AL. TTF CONTROL OF IN SITU GRAFT
489
competitive flow situations. In our experience it may prevent early postoperative ischemia secondary to technical imperfections that can impair the mid-term patency of the graft (2).
REFERENCES 1. Di Giammarco G, Pano M, Cirmeni S, et al: Predictive value of intraoperative transit-time flow measurement for shortterm graft patency in coronary surgery. J Thorac Cardiovasc Surg 2006;132(3):468–474. 2. Tokuda Y, Song MH, Oshima H, et al: Predicting midterm coronary artery bypass graft failure by intraoperative transit time flow measurement. Ann Thorac Surg 2008;86(2):532– 536. 3. Pettinari M, Sergeant P, Meuris B: Quantification of operational learning in off-pump coronary bypass. Eur J Cardiothorac Surg 2013;43(4):709–714. 4. Torchiana DF, Vine AJ, Titus JS, et al: The temperature dependence of cardioplegic distribution in the canine heart. Ann Thorac Surg 2000;70:614–620. 5. Jelenc M, Jelenc B, Kokocovnick T, et al: Understanding coronary artery bypass transit time flow curves: Role of bypass graft compliance. Interact Cardiovasc Thorac Surg 2013;18(2):164–168.
487
SURGICAL TECHNIQUE ___________________________________________________________
On Pump Evaluation of the Anastomotic Patency of In Situ Arterial Grafts Vasileios Tsiopoulos, M.D., Claudio Pragliola, M.D., Mario Gaudino, M.D., and Massimo Massetti, M.D. Dipartimento di Scienze Cardiovascolari, Unita` di Chirurgia del Cuore e dello Scompenso Cardiaco, Universita` Cattolica del Sacro Cuore, Policlinico Agostino Gemelli, Roma, Italy ABSTRACT We describe a variation of the standard intraoperative transit time flow evaluation that allows the assessment of the anastomotic patency of in situ arterial grafts before the release of the aortic cross clamp. The advantages of this technique are the immediate correction of technical imperfections and the evaluation of native competitive flow situations that may compromise long-term patency. doi: 10.1111/jocs.12315 (J
Card Surg 2014;29:487–489)
The advantages of routine intraoperative transit-time flow control (TTF) in coronary artery surgery have been clearly demonstrated.1 The analysis of the morphology of the flow curve in the grafts provides a reliable assessment of the technical accuracy of the anastomosis and may also predict the durability of the revascularization.2 Usually in cases using cardioplegia the TTF evaluation is performed at the end of the procedure under stable hemodynamic conditions after weaning the patients from the cardiopulmonary bypass. This strategy has two major disadvantages: (1) whenever it is necessary to revise an anastomosis the extracorporeal circulation has to be reestablished, the aorta recross-clamped and the cardioplegia reinfused; (2) TTF evaluation in these conditions is subject to the confounding effect of the interaction between native and graft flow that, in case of nonocclusive stenosis of the target vessel, can lead to inaccurate and misleading results. We propose a simple technical variation that enables an immediate evaluation of the anatomic patency of the anastomosis of in situ arterial grafts before the release of the aortic cross-clamp, allowing a prompt revision in case of malfunction and thus avoiding the confounding effects of native competitive flow.
Conflict of interest: The authors acknowledge no conflict of interest in the submission. Address for correspondence: Claudio Pragliola, M.D., Dipartimento di Scienze Cardiovascolari, Policlinico A. Gemelli, Largo Gemelli 8, 00168 Roma, Italy. Fax: þ39-06-3015-5881; e-mail: [email protected]
TECHNIQUE The principle behind this technique is the presence of residual anterograde flow in the native coronary artery. With the aorta cross-clamped the TTF probe is applied to the in situ graft immediatly after the completion of the anastomosis. The proximal grafted native coronary is gently snared as described for off-pump coronary artery bypass (OPCAB) surgery.3 In these conditions the flow curve recorded is driven directly by the heart lung machine and shows a sinusoid pattern determined by the roller pump (Fig. 1). With a mean systemic pressure of 65 to 70 mmHg, in absence of competitive flow from the native coronary artery, we consider acceptable a minimal flow of 15 mL/min mmHg2 into the distal edge of the anastomosis. After this evaluation the proximal snare on the native coronary artery is released and antegrade cardioplegic solution is infused into the aortic root at a controlled pressure of 100 mmHg. In presence of a nonocclusive stenosis of the target native vessel, this antegrade flow of cardioplegia competes with that of the graft; the result is a progressive reduction of the graft flow easily recordable with the TTF evaluation (Fig. 2). It must be noted that during the infusion of the cardioplegia the flow into the in situ graft rapidly declines to 0 mL/min and the sinusoidal curve partially or completely falls below this value indicating a flow reversal into the graft (Fig. 2, lower part). This pattern indicates the patency of the proximal edge of the anastomosis. The reduction of infusion in the aortic root leads to gradual reversal of this phenomenon with restoration of initial graft flow. In Y arterial grafts the probe is placed on the common branch and a delicate vessel clamp is alternatively
488
PRAGLIOLA, ET AL. TTF CONTROL OF IN SITU GRAFT
J CARD SURG 2014;29:487–489
Figure 1. In situ internal thoracic artery (ITA) to left anterior descending artery (LAD). In this patient the circulation was supported by a roller pump. Cardioplegia is off.
moved on the two branches of the Y. With these principles in mind the procedure can be adapted also to sequential grafts in order to check all the individual anastomosis. All patients undergoing myocardial revascularization with ‘‘in situ’’ arterial grafts had their anastomoses routinely checked since July 2011. In this period 4.4% of the 4141 anastomoses in 1414 patients were revised before and 0.2% after the release of the aortic crossclamp. Additionally four patients (0.4%) were submitted to an early postoperative coronary angiography and received a percutaneous coronary angioplasty of the native vessel for an anastomotic malfunction.
DISCUSSION This procedure was conceived to improve the anatomic patency of in situ arterial grafts. The evaluation is very fast and easy to perform, does not modify the standard operative technique, and can be completed in less than two minutes. It provides information regarding the anatomic patency of the anastomosis and allows immediate revision in case of suspected malfunction. Bidirectional flow can be checked by snaring the target coronary artery proximally and distally to the anastomosis and recording the flow alternatively releasing the snares. The same concept applies to
Figure 2. In situ ITA to the LAD. In the upper quadrant the cardioplegia is off. In the lower quadrant the flow of the cardioplegia into the native vessel competes with the flow into the graft.
J CARD SURG 2014;29:487–489
sequential grafts: the anastomoses can be checked one by one by placing several clamps along the conduit. The described method has the additional advantage of evaluating graft flow in the absence of competitive flow from the native vessel. This is of particular relevance in case of subocclusive target vessel stenosis: a situation where classical TTF evaluation can give doubtful and misleading results and even lead to unnecessary revision of the anastomosis. We are aware of the fact that other nontechnical factors such as the myocardial temperature, the composition and the temperature of the cardioplegia,4 and the extension and the resistence of the graft and coronary vascular bed5 may influence the flow at the anastomosis. To overcome this possible bias we have learned from experience that a minimal value of 15 mL/min is easily obtainable with an optimal anastomosis and is independent from nontechnical factors. In conclusion, our technique does not intend to replace the standard TTF evaluation performed at the end of the surgical procedure but it allows a simple and immediate evaluation of the anastomosis after its completion. The procedure has potential advantages in case of technical imperfection of the anastomosis and in native
PRAGLIOLA, ET AL. TTF CONTROL OF IN SITU GRAFT
489
competitive flow situations. In our experience it may prevent early postoperative ischemia secondary to technical imperfections that can impair the mid-term patency of the graft (2).
REFERENCES 1. Di Giammarco G, Pano M, Cirmeni S, et al: Predictive value of intraoperative transit-time flow measurement for shortterm graft patency in coronary surgery. J Thorac Cardiovasc Surg 2006;132(3):468–474. 2. Tokuda Y, Song MH, Oshima H, et al: Predicting midterm coronary artery bypass graft failure by intraoperative transit time flow measurement. Ann Thorac Surg 2008;86(2):532– 536. 3. Pettinari M, Sergeant P, Meuris B: Quantification of operational learning in off-pump coronary bypass. Eur J Cardiothorac Surg 2013;43(4):709–714. 4. Torchiana DF, Vine AJ, Titus JS, et al: The temperature dependence of cardioplegic distribution in the canine heart. Ann Thorac Surg 2000;70:614–620. 5. Jelenc M, Jelenc B, Kokocovnick T, et al: Understanding coronary artery bypass transit time flow curves: Role of bypass graft compliance. Interact Cardiovasc Thorac Surg 2013;18(2):164–168.
