Ann Thorac Surg 2006;81:756-757
© 2006 The Society of Thoracic Surgeons
How to do it
Valve Replacement After T-Grafting: "Beating Heart Surgery"
Hendrick B. Barner, MD
a
,
b
,
*
,
Thoralf M. Sundt, III, MD
a
,
b
,
Cliff K. Choong, FRACS
a
,
b
a Division of Cardiothoracic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
b Christian Hospital Northeast, St. Louis, Missouri
Accepted for publication November 22, 2004.
* Address correspondence to Dr Barner, 6125 Clayton Ave, Suite 430, St. Louis, MO 63139 (Email: hendrick.barner{at}tenethealth.com).
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Abstract
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Patent internal thoracic and radial artery T-graft will adequately perfuse the heart during reoperation. Five of 1,023 patients with prior T-grafting had aortic (3) or mitral valve redo operations in which the heart was allowed to beat (after an initial dose of cardioplegia) during the operation without clamping the patent T-graft. Rapid resumption of cardiac function after one dose of cardioplegia and no intraoperative or postoperative evidence of myocardial infarction indicated adequacy of perfusion without apparent myocardial injury. This approach avoids injury to the T-graft from dissection and clamping, saves time, and simplifies the operation.
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Introduction
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The T-graft can theoretically perfuse most of the myocardium despite aortic cross-clamping depending on coronary anatomy, the position of occlusive coronary lesions, and conduit anastomotic locations. Repeated observation of resumption of contractile activity a few minutes after reperfusion by a T-graft with the aorta clamped suggested this potential. In January 2000, a patient with a prior (5 years) internal thoracic artery (ITA) and radial artery (RA) T-graft required reoperation for aortic valve replacement. Antegrade and retrograde 34°C blood cardioplegia was given while the T-graft was dissected for clamping, but cardiac contractions returned before the dissection was completed, indicating the capability of this configuration to perfuse the myocardium. This patient had the proximal ITA clamped, but in subsequent cases we chose not to clamp the T-graft during reoperative valve replacement as dissection of the T-graft main stem may be challenging and clamping may cause intimal damage. We report our experience with 5 consecutive patients who were managed as such.
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Technique
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From October 1993 through October 2001, 1,023 patients had myocardial revascularization with the ITA and RA T-graft [1]. Five patients returned for valve repair/replacement (Table 1) beginning July 3, 2000. All patients had prior grafting (35 to 80 months) of the left ITA to the left anterior descending system and the RA to branches of the circumflex and right coronary arteries with proximal RA anastomosis to the ITA. All patients had preoperative cardiac catheterization including coronary angiography and echocardiography.
All operations were conducted through a median sternotomy and the systemic temperature was allowed to drift to 34°C. All patients had one dose of antegrade and retrograde (tepid [34°C]) blood cardioplegia, and when the heart resumed a sinus rhythm (within 2 to 5 minutes) it was elected to use no additional cardioplegia, and the heart was allowed to beat throughout the procedure. In 1 patient (patient 2), the heart was perfused with retrograde cardioplegia every 10 minutes, because the RA graft to the right posterior descending artery was occluded and the heart maintained a sinus rhythm throughout. In another patient (patient 5), with radial artery occlusion to the posterior descending artery, a new vein graft was placed to this artery and continuously perfused with tepid blood with persistence of a sinus rhythm during repair of the mitral valve.
One patient (patient 4) died on postoperative day 3 of sepsis, low cardiac output, and multiorgan failure. This 61-year-old woman had hypertension, diabetes, obesity, renal failure requiring dialysis, and mitral valve endocarditis due to enterococcus, which was treated for 8 days with early operation indicated by multiple, small, acute cerebral infarctions, and deteriorating hemodynamics requiring dobutamine. She was weaned from cardiopulmonary bypass with inotropic and vasopressor support but required intraaortic balloon pump insertion 6 hours postoperatively because of persistent low cardiac output, which was not altered by hemodialysis.
The other 4 patients had courses that were free of significant complications, including myocardial infarction, low cardiac output, renal failure, and sepsis. They were all weaned from bypass with no or minimal inotropic support, which was needed for < 24 hours. They continue to survive 1 to 39 months later.
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Comment
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Before the advent of cardioplegia, aortic valve replacement was commonly performed with a beating heart by continuous perfusion of the directly cannulated coronary ostia, whereas mitral valve procedures were conducted without aortic cross-clamping or with intermittent clamping [2]. The T-graft provides substantial perfusion of the heart in some patients and only partial in others depending on the distribution of the T-graft and the location of coronary lesions. In the former, the heart is adequately perfused and continues to beat in most instances if myocardial cooling does not induce fibrillation. We do not use fibrillation as an operative technique, as we are concerned about hypoperfusion occurring in the hypertrophied heart. In our experience, we have continued to place catheters for antegrade and retrograde cardioplegia and to give an initial dose of tepid blood cardioplegia. Resumption of a sinus rhythm without electrocardiographic evidence of ischemia has indicated to us that cardiac perfusion was adequate and no additional cardioplegia was infused except for the 2 patients having a new vein graft to the posterior descending artery for closure of the distal RA anastomosis. In the first patient (patient 2), we gave retrograde 34°C blood cardioplegia every 10 minutes with persistence of a sinus rhythm. In the second patient (patient 5), the new vein graft was continuously perfused with 34°C blood from the bypass circuit and sinus rhythm persisted.
We believe the myocardium was adequately perfused in these patients on the basis of the need for minimal inotropic support (except for patient 4) and the lack of electrocardiographic evidence of infarction. The patient who died (patient 4) had ongoing sepsis and preoperatively had a large mitral valve vegetation, annular involvement, and clinical heart failure due to severe mitral regurgitation. In this patient, we cannot prove that the myocardium was optimally preserved, but intraoperative transesophageal electrocardiography did not reveal regional wall motion abnormalities and the postoperative electrocardiogram did not have a Q-wave.
The T-graft principle is unique in that all conduit flow to the heart passes through the proximal left ITA and then through the two limbs consisting of the left ITA and originally the right ITA [3]. Some have used the RA as the second conduit (instead of the right ITA), which has been our practice [1]. Because of the single source of inflow there has been understandable skepticism over the adequacy of flow. However, intraoperative flow measurements have suggested adequate flow with this configuration [4], and coronary flow reserve at 6 months postoperatively has improved to normal levels [5], which is consistent with conduit remodeling [6].
The left ITA and RA T-graft lies out of the field of dissection required for valve operations with the "T" anastomosis usually positioned 1 to 2 cm anterior to the left atrial appendage and the left ITA lying intrapleurally parallel to the phrenic nerve. This simplifies dissection for reoperative valve replacement, particularly when compared with an anterior crossing right ITA, transverse sinus routing, or with aortic anastomosis. With the left ITA and RA T-graft, there is usually no graft arising from the aorta.
Conduct of the operation has not been compromised by cardiac activity, which is slow and produces little inconvenience. Retrograde flow from the coronary ostia has been minimal, presumably because of proximal coronary disease, and we have not found it necessary to occlude the coronary artery mechanically. Exposure of the mitral valve has been done with the superior septal approach. Thebesian flow into the cavity of the left ventricle has been managed with intermittent aspiration of the ventricle and continuously from the left atrium.
Beating heart valve replacement by continuous perfusion through a previously placed left ITA and RA T-graft avoids the need for dissection of the T-graft and the potential for T-graft injury. The T anastomosis lies anterior to the left atrial appendage, and it is well away from structures that require dissection or exposure to operate on the aortic or mitral valves because the RA passes around the left side of the left ventricle to reach circumflex branches and posterior branches of the right coronary. We have not recognized hypoperfusion of the heart at the initial operation or subsequently with this strategy, and we will continue to use this strategy.
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References
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- Barner HB, Sundt III TM, Bailey MS, et al. Intermediate term results of complete arterial revascularization in over 1000 patients using an internal thoracic artery/radial artery T-graft Ann Surg 2001;234:447-452.[Medline]
- McGoon DC, Pestana C, Moffitt EA. Decreased risk of aortic valve surgery J Thorac Cardiovasc Surg 1965;91:779-783.
- Tector AJ, Amundsen S, Schmal TM, et al. Total revascularization with T-grafts Ann Thorac Surg 1994;57:33-39.[Abstract]
- Affleck DG, Barner HB, Bailey MS, et al. Flow dynamics of the internal thoracic and radial artery T-graft Ann Thorac Surg 2004;78:1290-1294.[Abstract/Free Full Text]
- Wendler O, Hennen B, Markwirth T, et al. T-grafts with the right internal thoracic artery to the left internal thoracic artery versus the left internal thoracic artery and radial arteryflow dynamics in the internal thoracic artery mainstem. J Thorac Cardiovasc Surg 1999;118:841-848.[Abstract/Free Full Text]
- Barner HB. Remodeling of arterial conduits in coronary grafting Ann Thorac Surg 2002;73:1341-1345.[Abstract/Free Full Text]
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Abstract
Introduction
