- Email: [email protected]
Left internal mammary artery branches after minimally invasive harvesting
Ann Thorac Surg 2000;69:1640 –50
survival by single variate analysis in stage 1 adenocarcinoma or bronchioloalveolar carcinoma. The results do not show a significant difference. Yung-Chie Lee, MD, PhD Yih-Leong Chang, MD Shi-Ping Luh, MD Jang-Ming Lee, MD Jin-Shing Chen, MD Department of Surgery College of Medicine National Taiwan University No. 7. Chung-Shan South Rd Taipei 10016, Taiwan e-mail: [email protected].
Partial Clamping of the Inferior Vena Cava To the Editor: We would like to thank Dr Dagenais and his group for highlighting a simple and effective maneuver for controlling cardiac preload during cardiac surgery [1]. Dr Dagenais and his group have utilized intermittent partial snaring of the IVC as a technique to reduce pulmonary hypertension during beating heart surgery. According to their article, this helps to reduce the pulmonary hypertension that results from mechanical distortion of the heart, thereby facilitating completion of the anastomosis. We have been using the technique of partial occlusion of the IVC under many circumstances, after routine OHS. We frequently use this maneuver when we want to take additional sutures on the ascending aorta. These could be sutures on the proximal anastomoses, or additional sutures to control bleeding from the aortic suture lines after aortic valve replacement, Ross operation, or Bentall’s procedure. In this circumstance, most junior surgeons entrusted with the duty of ensuring a dry closure struggle to take safe sutures on a tense aorta. Our technique is a temporary partial cross-clamping of the IVC, using the aortic cross-clamp. This reduces the preload, bringing the CVP down to about 2 to 3 cm H2O, “emptying” the RV and PA, and reducing the systemic pressure to about 60 mm Hg systolic. At this pressure, it is easy to take safe sutures and manipulate the aorta. The knots can also be tied securely with no fear of their “cutting through.” Our anesthesiologists are extremely happy with this surgical control of preload, and actually feel that it enables them to maintain hemodynamics with far fewer interventions than would be needed with “pharmacological phlebotomy” using high doses of GTN/SNP. Of course, additional vigilance is needed while this maneuver is performed. Because we, and others [2], use the method in a situation where a temporary reduction of systemic pressures is required, we have some reservations about its safety when there is hypotension and a tense PA during beating heart surgery. Would that not cause a further fall in the blood pressure and jeopardize the myocardium, which is already suffering the insult of distortion, subendocardial ischemia, and coronary occlusion? Lalit Kapoor, MCh S. Pande, MCh S. Singh, MD BM Birla Heart Research Centre 1/1 National Library Ave © 2000 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
CORRESPONDENCE
1649
Calcutta 700 027, India e-mail: [email protected]
References 1. Dagenais F, Cartier R. Pulmonary hypertension during beating heart coronary surgery: intermittent inferior vena cava snaring. Ann Thorac Surg 1999;68:1094–5. 2. Nishikimi N, Usui A, Ishiguchi T, Matsushita M, Sakurai T, Nimura Y. Vena cava occlusion with balloon to control blood pressure during deployment of transluminally placed endovascular graft. Am J Surg 1998;176:233– 4.
Reply To the Editor: We agree with the comment of Dr Kapoor. We also often use the inferior vena cava cross-clamping maneuver in cases where additional sutures are needed to secure the homeostasis, such as complex aortic reconstruction. However, the situations we have described in the beating heart surgery are different. We aim for right ventricular (RV) preload reduction in a situation where the left ventricle (LV) is distended. By decreasing the RV preload, we generally decrease the LV preload. This distension is normally due to ischemia or temporary mitral insufficiency and impedes LV performance leading to hypotension. In these circumstances, the IVC cross-clamping act as a bolus of IV nitroglycerine but has the advantage of being immediately effective. The instant drop in LV overload immediately brings back the myocardium on the steep part of its starling curve thereby improving hemodynamics. It allows the anesthesiologist to readjust the medication without exposing the patient to sustained prolonged hypotension. It is likely that if the preload restriction is maintained for a too long period of time, hypotension will occurred. Raymond Cartier, MD Department of Surgery Montreal Heart Institute 5000 Belanger St E Montreal, PQ, HII 1C8, Canada
Left Internal Mammary Artery Branches After Minimally Invasive Harvesting To the Editor: Calafiore and colleagues have elegantly examined the anatomy and size of persistent left internal mammary artery (LIMA) branches after use of the vessel as a coronary artery graft after harvesting both in an open fashion (sternotomy) and a minimally invasive fashion (left anterior small thoracotomy) [1]. Part of their conclusion, however, that the number and nature of these persistent (or perhaps newly developing) branches is independent of the harvesting technique, appears to be at variance with the data presented. Considering only those patients in whom a persistent lateral costal branch, persistent first intercostal branch, or any other branch greater than 1 mm diameter was seen (and disregarding those branches of less than 1 mm in diameter), in the minimally invasive group, these numbered 54 of 150, and in the open group, these numbered 21 of 150, a 2.5 times increased incidence in the minimally invasive group and a statistically significant difference by 2 test with p less than 0.0001, relative risk 1.69 (95% confidence 0003-4975/00/$20.00
1650
CORRESPONDENCE
interval [CI] 1.37 to 2.06) and an odds ratio of 3.45 (95% CI 1.95 to 6.10). Whether these large persistent branches represent a clinically important entity is not addressed by this investigation and remains unclear. There are conflicting clinical and physiologic reports describing the possible relationship between such branches and residual or recurrent angina [2, 3]. However, on the basis of these data, it is possible to say that LIMA harvesting by left anterior small thoracotomy is a risk factor for the presence of persistent large LIMA branches as described. Paul Peters, FRCS(CTh) Department of Cardiothoracic Surgery Royal Prince Alfred Hospital Missenden Rd Camperdown, Sydney NSW 2050 Australia e-mail: [email protected].
References 1. Calafiore AM, Contini M, Iaco AL, et al. Angiographic anatomy of the grafted left internal mammary artery. Ann Thorac Surg 1999;68:1636–9. 2. Gaudino M, Serricchio M, Glieca F, et al. Steal phenomenon from mammary side branches: when does it occur? Ann Thorac Surg 1998;66:2056– 62. 3. Hartz RS, Heuser RR. Embolization of IMA side branch for post-CABG ischemia. Ann Thorac Surg 1997;63:1765– 6.
Reply
Ann Thorac Surg 2000;69:1640 –50
of view; for instance, had one of these branches some diastolic flow (to the lung or elsewhere)? Coming back to the questions that Dr Peters raised, the purpose of the paper was different. As it is possible to elicit from Table 1, there are 55 cases in Group A (LIMA harvested via a LAST) and 54 in Group B (LIMA harvested via a median sternotomy), where the common origin causes the persistence of large branches (which are not possible to be divided during LIMA harvest). Furthermore, 15 cases in Group A and 17 in Group B showed the persistence of the lateral costal branch that, coming out in the first 1 cm of the LIMA, cannot be ligated at the origin. Globally, 46.7% of the cases in Group A and 47.3% in Group B show important undivided branches. The consideration that is easily drawn is that the persistence of these branches, a constant since the beginning of coronary surgery, does not cause any limitation to the coronary flow. This paper wants to emphasize only the anatomical aspect of a functional problem, but, at the same time, it wants to give another contribution to the comprehension of a problem that, even if present every day in coronary surgery, was not well focused before the advent of MIDCAB. Antonio M. Calafiore, MD Department of Cardiac Surgery “G. D’Annunzio” University St Camillo de’ Lellis Hospital Via C. Forlanini, 50 66100 Chieti Italy e-mail: [email protected].
To the Editor:
References
I read with interest the comments of Dr Peters. Basically, what he writes is true. Table 1 [1] shows clearly that the incidence of branches with a size equal to or greater than 1 mm is significantly higher in patients where the LIMA was harvested via a LAST ( p ⬍ 0.001). However, this observation brings us again to the problem of flow competition: can the systolic flow of a persisting branch compete with a coronary flow that is essentially diastolic? This is a never-ending story; in fact, even if some detailed reports demonstrate that this is not possible [2– 4], another case report [5] showed anecdotal cases where angina was relieved, ligating or embolizing the undivided branch. The problem of these case reports is that they are never well studied from the pathophysiologic point
1. Calafiore AM, Contini M, Iaco` AL, et al. Angiographic anatomy of the grafted left internal mammary artery. Ann Thorac Surg 1999;68:1636–9. 2. Gaudino M, Serricchio M, Glieca F, et al. Steal phenomenon from mammary side branches: when does it occur? Ann Thorac Surg 1998;66:2056– 62. 3. Luise R, Teodori G, Di Giammarco G, et al. Persistence of mammary artery branches and blood supply to the left anterior descending artery. Ann Thorac Surg 1997;63:1759– 64. 4. Kern MJ. Mammary side branch steal: is this a real or even clinically important phenomenon? Ann Thorac Surg 1998;66: 1873–5. 5. Hartz RS, Heuser RR. Embolization of IMA side branch for post CABG ischemia. Ann Thorac Surg 1997;63:1765– 6.
© 2000 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
0003-4975/00/$20.00
survival by single variate analysis in stage 1 adenocarcinoma or bronchioloalveolar carcinoma. The results do not show a significant difference. Yung-Chie Lee, MD, PhD Yih-Leong Chang, MD Shi-Ping Luh, MD Jang-Ming Lee, MD Jin-Shing Chen, MD Department of Surgery College of Medicine National Taiwan University No. 7. Chung-Shan South Rd Taipei 10016, Taiwan e-mail: [email protected].
Partial Clamping of the Inferior Vena Cava To the Editor: We would like to thank Dr Dagenais and his group for highlighting a simple and effective maneuver for controlling cardiac preload during cardiac surgery [1]. Dr Dagenais and his group have utilized intermittent partial snaring of the IVC as a technique to reduce pulmonary hypertension during beating heart surgery. According to their article, this helps to reduce the pulmonary hypertension that results from mechanical distortion of the heart, thereby facilitating completion of the anastomosis. We have been using the technique of partial occlusion of the IVC under many circumstances, after routine OHS. We frequently use this maneuver when we want to take additional sutures on the ascending aorta. These could be sutures on the proximal anastomoses, or additional sutures to control bleeding from the aortic suture lines after aortic valve replacement, Ross operation, or Bentall’s procedure. In this circumstance, most junior surgeons entrusted with the duty of ensuring a dry closure struggle to take safe sutures on a tense aorta. Our technique is a temporary partial cross-clamping of the IVC, using the aortic cross-clamp. This reduces the preload, bringing the CVP down to about 2 to 3 cm H2O, “emptying” the RV and PA, and reducing the systemic pressure to about 60 mm Hg systolic. At this pressure, it is easy to take safe sutures and manipulate the aorta. The knots can also be tied securely with no fear of their “cutting through.” Our anesthesiologists are extremely happy with this surgical control of preload, and actually feel that it enables them to maintain hemodynamics with far fewer interventions than would be needed with “pharmacological phlebotomy” using high doses of GTN/SNP. Of course, additional vigilance is needed while this maneuver is performed. Because we, and others [2], use the method in a situation where a temporary reduction of systemic pressures is required, we have some reservations about its safety when there is hypotension and a tense PA during beating heart surgery. Would that not cause a further fall in the blood pressure and jeopardize the myocardium, which is already suffering the insult of distortion, subendocardial ischemia, and coronary occlusion? Lalit Kapoor, MCh S. Pande, MCh S. Singh, MD BM Birla Heart Research Centre 1/1 National Library Ave © 2000 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
CORRESPONDENCE
1649
Calcutta 700 027, India e-mail: [email protected]
References 1. Dagenais F, Cartier R. Pulmonary hypertension during beating heart coronary surgery: intermittent inferior vena cava snaring. Ann Thorac Surg 1999;68:1094–5. 2. Nishikimi N, Usui A, Ishiguchi T, Matsushita M, Sakurai T, Nimura Y. Vena cava occlusion with balloon to control blood pressure during deployment of transluminally placed endovascular graft. Am J Surg 1998;176:233– 4.
Reply To the Editor: We agree with the comment of Dr Kapoor. We also often use the inferior vena cava cross-clamping maneuver in cases where additional sutures are needed to secure the homeostasis, such as complex aortic reconstruction. However, the situations we have described in the beating heart surgery are different. We aim for right ventricular (RV) preload reduction in a situation where the left ventricle (LV) is distended. By decreasing the RV preload, we generally decrease the LV preload. This distension is normally due to ischemia or temporary mitral insufficiency and impedes LV performance leading to hypotension. In these circumstances, the IVC cross-clamping act as a bolus of IV nitroglycerine but has the advantage of being immediately effective. The instant drop in LV overload immediately brings back the myocardium on the steep part of its starling curve thereby improving hemodynamics. It allows the anesthesiologist to readjust the medication without exposing the patient to sustained prolonged hypotension. It is likely that if the preload restriction is maintained for a too long period of time, hypotension will occurred. Raymond Cartier, MD Department of Surgery Montreal Heart Institute 5000 Belanger St E Montreal, PQ, HII 1C8, Canada
Left Internal Mammary Artery Branches After Minimally Invasive Harvesting To the Editor: Calafiore and colleagues have elegantly examined the anatomy and size of persistent left internal mammary artery (LIMA) branches after use of the vessel as a coronary artery graft after harvesting both in an open fashion (sternotomy) and a minimally invasive fashion (left anterior small thoracotomy) [1]. Part of their conclusion, however, that the number and nature of these persistent (or perhaps newly developing) branches is independent of the harvesting technique, appears to be at variance with the data presented. Considering only those patients in whom a persistent lateral costal branch, persistent first intercostal branch, or any other branch greater than 1 mm diameter was seen (and disregarding those branches of less than 1 mm in diameter), in the minimally invasive group, these numbered 54 of 150, and in the open group, these numbered 21 of 150, a 2.5 times increased incidence in the minimally invasive group and a statistically significant difference by 2 test with p less than 0.0001, relative risk 1.69 (95% confidence 0003-4975/00/$20.00
1650
CORRESPONDENCE
interval [CI] 1.37 to 2.06) and an odds ratio of 3.45 (95% CI 1.95 to 6.10). Whether these large persistent branches represent a clinically important entity is not addressed by this investigation and remains unclear. There are conflicting clinical and physiologic reports describing the possible relationship between such branches and residual or recurrent angina [2, 3]. However, on the basis of these data, it is possible to say that LIMA harvesting by left anterior small thoracotomy is a risk factor for the presence of persistent large LIMA branches as described. Paul Peters, FRCS(CTh) Department of Cardiothoracic Surgery Royal Prince Alfred Hospital Missenden Rd Camperdown, Sydney NSW 2050 Australia e-mail: [email protected].
References 1. Calafiore AM, Contini M, Iaco AL, et al. Angiographic anatomy of the grafted left internal mammary artery. Ann Thorac Surg 1999;68:1636–9. 2. Gaudino M, Serricchio M, Glieca F, et al. Steal phenomenon from mammary side branches: when does it occur? Ann Thorac Surg 1998;66:2056– 62. 3. Hartz RS, Heuser RR. Embolization of IMA side branch for post-CABG ischemia. Ann Thorac Surg 1997;63:1765– 6.
Reply
Ann Thorac Surg 2000;69:1640 –50
of view; for instance, had one of these branches some diastolic flow (to the lung or elsewhere)? Coming back to the questions that Dr Peters raised, the purpose of the paper was different. As it is possible to elicit from Table 1, there are 55 cases in Group A (LIMA harvested via a LAST) and 54 in Group B (LIMA harvested via a median sternotomy), where the common origin causes the persistence of large branches (which are not possible to be divided during LIMA harvest). Furthermore, 15 cases in Group A and 17 in Group B showed the persistence of the lateral costal branch that, coming out in the first 1 cm of the LIMA, cannot be ligated at the origin. Globally, 46.7% of the cases in Group A and 47.3% in Group B show important undivided branches. The consideration that is easily drawn is that the persistence of these branches, a constant since the beginning of coronary surgery, does not cause any limitation to the coronary flow. This paper wants to emphasize only the anatomical aspect of a functional problem, but, at the same time, it wants to give another contribution to the comprehension of a problem that, even if present every day in coronary surgery, was not well focused before the advent of MIDCAB. Antonio M. Calafiore, MD Department of Cardiac Surgery “G. D’Annunzio” University St Camillo de’ Lellis Hospital Via C. Forlanini, 50 66100 Chieti Italy e-mail: [email protected].
To the Editor:
References
I read with interest the comments of Dr Peters. Basically, what he writes is true. Table 1 [1] shows clearly that the incidence of branches with a size equal to or greater than 1 mm is significantly higher in patients where the LIMA was harvested via a LAST ( p ⬍ 0.001). However, this observation brings us again to the problem of flow competition: can the systolic flow of a persisting branch compete with a coronary flow that is essentially diastolic? This is a never-ending story; in fact, even if some detailed reports demonstrate that this is not possible [2– 4], another case report [5] showed anecdotal cases where angina was relieved, ligating or embolizing the undivided branch. The problem of these case reports is that they are never well studied from the pathophysiologic point
1. Calafiore AM, Contini M, Iaco` AL, et al. Angiographic anatomy of the grafted left internal mammary artery. Ann Thorac Surg 1999;68:1636–9. 2. Gaudino M, Serricchio M, Glieca F, et al. Steal phenomenon from mammary side branches: when does it occur? Ann Thorac Surg 1998;66:2056– 62. 3. Luise R, Teodori G, Di Giammarco G, et al. Persistence of mammary artery branches and blood supply to the left anterior descending artery. Ann Thorac Surg 1997;63:1759– 64. 4. Kern MJ. Mammary side branch steal: is this a real or even clinically important phenomenon? Ann Thorac Surg 1998;66: 1873–5. 5. Hartz RS, Heuser RR. Embolization of IMA side branch for post CABG ischemia. Ann Thorac Surg 1997;63:1765– 6.
© 2000 by The Society of Thoracic Surgeons Published by Elsevier Science Inc
0003-4975/00/$20.00