reduction in the incidence of sternal wound infection from 5.6% to 0% at 30 days that although not ”statistically signiﬁcant” would be clinically very important. Indeed, several intraoperative methods can be used to reduce the risk of sternal wound complications, such as particular skin and sternal suturing techniques and the application of topical antibacterial agents, and these methods have been previously discussed by our institution . The important point is that although there is an associated increased risk of sternal wound complication, the use of BIMA grafts has been shown to improve long-term survival compared with the use of a single internal mammary artery [4, 5]. Therefore, the increased risk of sternal wound complications associated with BIMA grafts should not discourage surgeons from employing such a revascularization strategy; rather, this strategy should be managed with appropriate preoperative planning, intraoperative technique, and postoperative wound management, such as that described by Santarpino and colleagues. Syed M. Rehman, MD Department of Cardiothoracic Surgery Oxford University Hospitals NHS Trust Headley Way Headington Oxford OX3 9DU United Kingdom email: [email protected]
Kevin Cheng, BMBCh Medical Sciences Division University of Oxford Oxford OX1 2JD United Kingdom David P. Taggart, MD, PhD Department of Cardiothoracic Surgery Oxford University Hospitals NHS Trust Oxford OX3 9DU United Kingdom
References 1. Santarpino G, Gazdag L, Vogt F, Ledwon M. Randomized study for mammary artery harvesting: please, also consider wound management! (letter). Ann Thorac Surg 2016;101:2025. 2. Cheng K, Rehman SM, Taggart DP. A review of differing techniques of mammary artery harvesting on sternal perfusion: time for a randomized study? Ann Thorac Surg 2015;100:1942–53. 3. Rehman SM, Elzain O, Mitchell J, et al. Risk factors for mediastinitis following cardiac surgery: the importance of managing obesity. J Hosp Infect 2014;88:96–102. 4. Taggart DP, Altman DG, Gray AM, et al. Randomized trial to compare bilateral vs. single internal mammary coronary artery bypass grafting: 1-year results of the Arterial Revascularisation Trial (ART). Eur Heart J 2010;31:2470–81. 5. Yi G, Shine B, Rehman SM, Altman DG, Taggart DP. Effect of bilateral internal mammary artery grafts on long-term survival: a meta-analysis approach. Circulation 2014;130:539–45.
Rapid Rewarming During Cardiopulmonary Bypass Is Associated With Cerebral Injury To the Editor: Hori and colleagues  investigated rewarming strategies in cardiopulmonary bypass (CPB) and their relationship with Ó 2016 by The Society of Thoracic Surgeons Published by Elsevier
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plasma levels of glial ﬁbrillary acidic protein (GFAP), a serum protein generated by ischemic or necrotic cerebral astrocytes, or both. These investigators conducted measurements of GFAP before and immediately after CPB, with the stated goal to correlate CPB perfusion temperature and rate of rewarming with release of this biomarker. GFAP is a sensitive marker for cerebral injury whose advantage over S100b and neuron-speciﬁc enolase is that its speciﬁcity is not inﬂuenced by extracranial contamination. GFAP therefore may have considerable value for determination of subtle forms of injury. In this current article, Hori and associates  demonstrate that higher GFAP levels correlate with increasingly rapid rewarming and with lower perfusion temperatures. These results support the recommendation in the recently published practice guideline “Temperature Management During Cardiopulmonary Bypass” . The recommendation is class IIa, level of evidence B, and it speciﬁcally states that “it is reasonable to maintain a rewarming rate 0.5 C/min” (regardless of perfusate temperature). Although rewarming rates in the article did not exceed 0.5 C/ min, the relationship between rapid rewarming and increased release of GFAP was clearly demonstrated. The data in the article reveal “a 29.8% (95% CI [conﬁdence interval], 14.1 to 47.8) increase in plasma GFAP after surgery for every 0.1 C/min increase in rewarming rate.” In addition, the incidence of stroke as reported in the study at 3.9% had a correlation with rewarming rate: “The CPB rewarming rate was higher in patients with a stroke compared with patients without stroke (0.3 C/min 0.09 C/min versus 0.2 C/min 0.11 C/min; p ¼ 0.049).” These data reafﬁrm the recommendation to maintain rewarming rates at less than 0.5 C/min regardless of the perfusion temperature. The results and conclusion associate rapid rewarming with cerebral injury and suggest that the quantity of GFAP release may be a surrogate marker for this injury. The study does not suggest an ideal strategy for CPB rewarming; however, it does provide support for the guideline recommendation to minimize the rapidity of rewarming. Richard Engelman, MD Cardiac Surgical Research Baystate Medical Center 759 Chestnut St Springﬁeld, MA 01199 email: [email protected]
John W. Hammon, MD Surgery Wake Forest University School of Medicine Winston-Salem, North Carolina Robert A. Baker, PhD, CCP Cardiac Surgery Research & Perfusion Flinders University and Medical Centre Adelaide, South Australia Linda Shore-Lesserson, MD Cardiothoracic Anesthesiology Northshore-Long Island Jewish Medical Center New Hyde Park, New York
References 1. Hori D, Everett AD, Lee JK, et al. Rewarming rate during cardiopulmonary bypass is associated with release of glial ﬁbrillary acidic protein. Ann Thorac Surg 2015;100:1353–9. 0003-4975/$36.00
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2. Engelman RM, Baker RA, Likosky DS, et al. The Society of Thoracic Surgeons, the Society of Cardiovascular Anesthesiologists, the American Society of Extracorporeal Technology clinical practice guidelines for cardiopulmonary bypass: temperature management during cardiopulmonary bypass. Ann Thorac Surg 2015;100:748–57.
Reply To the Editor: Rewarming from hypothermia during cardiopulmonary bypass has been known for some time to predispose to cerebral injury through several proposed mechanisms, including inadvertent cerebral hyperthermia [1–3]. Prior studies that have investigated neurologic adverse events related to temperature management during cardiopulmonary bypass have mainly relied on clinical endpoints such as stroke or postoperative neurocognitive dysfunction. Our group has recently evaluated the relationship between rewarming rate and cerebral injury detected by the sensitive brain injury biomarker glial ﬁbrillary acid protein (GFAP) . This protein forms part of the structure of astrocytes, the most abundant cells of the brain. GFAP is rapidly released across the blood–brain barrier after ischemic brain injury . Thus, tracking plasma GFAP levels provides an objective measure of cerebral injury that overcomes the limitations of detecting such injury based on clinical stroke or postoperative cognitive dysfunction. We appreciate the current letter to the editor by Engleman and colleagues  drawing attention to their recent publication in which a rewarming rate during cardiopulmonary bypass of 0.5 C or lower was recommended. Our ﬁndings that rewarming rate, but not maximum body temperature after cardiopulmonary bypass, was associated with higher plasma GFAP levels early after operation does provide some support for this recommendation . However, the adjusted statistical model of our study showed an increase of nearly 30% in plasma GFAP (ng/mL) after operation for every 0.1 C/min increase in rewarming rate. The latter data suggest that the exact rewarming rate that is safe for the brain is not yet clearly known. Further research on different approaches to temperature management and rewarming from hypothermia during cardiopulmonary bypass seem warranted. In the meantime, it seems prudent for clinicians to consider the recommendations of Engleman and colleagues  and carefully monitor the rewarming rate during cardiopulmonary bypass as a measure to reduce the risk for neurologic adverse events. Daijiro Hori, MD Charles W. Hogue, MD
References 1. Croughwell N, Frasco P, Blumenthal J, Leone BJ, White WD, Reves JG. Warming during cardiopulmonary bypass is associated with jugular bulb desaturation. Ann Thorac Surg 1992;53:827–32. 2. Cook D, Orszulak T, Daly R, Buda D. Cerebral hyperthermia during cardiopulmonary bypass in adults. J Thorac Cardiovasc Surg 1996;111:268–9. 3. Hogue CW Jr, Palin CA, Arrowsmith JE. Cardiopulmonary bypass management and neurologic outcomes: an evidencebased appraisal of current practices. Anesth Analg 2006;103: 21–37. Ó 2016 by The Society of Thoracic Surgeons Published by Elsevier
4. Hori D, Everett AD, Lee JK, et al. Rewarming rate during cardiopulmonary bypass is associated with release of glial ﬁbrillary acidic protein. Ann Thorac Surg 2015;100:1353–9. 5. Herrmann M, Vos P, Wunderlich M, de Bruijn C, Lamers K. Release of glial tissue-speciﬁc proteins after acute stroke: a comparative analysis of serum concentrations of protein S100B and glial ﬁbrillary acidic protein. Stroke 2000;31:2670–7. 6. Engelman R, Hammon JW, Baker RA, Shore-Lesserson L. Rapid rewarming during cardiopulmonary bypass is associated with cerebral injury (letter). Ann Thorac Surg 2016;101:2026–7.
Strategies for Treatment of Cardiac Ischemic Complication After Heart Surgical Procedures: Is the Reoperation Really the Worst Option? To the Editor: We read with great interest the recently published study by Gaudino and colleagues . The authors, after analyzing the outcomes of 40 patients who underwent emergency coronary angiogram after a cardiac surgical procedure, found that this procedure is safe and concluded that coronary angiogram allows diagnosis and resolution of the hemodynamic instability in most cases. In the multivariate analysis independent risk factors for long-term mortality were combinedoperation and type of management (odds ratio 0.28). In other words, conservative management was a protective factor compared with reoperation. Indeed, in this study all 3 patients who underwent surgical procedures died within 30 days postoperatively. This discouraging result can lead surgeons to consider the reoperation as something that must be avoided. We believe that the ﬁndings by Gaudino and colleagues  have the inherent limitations of a small sample size, and caution must be used in interpreting these results. Larger series indeed do not conﬁrm these results. Davierwala and colleagues  analyzed the outcomes of 399 patients undergoing emergency coronary angiogram for perioperative myocardial infarction and found no signiﬁcant differences in rates of mortality among strategies (10.8% in the surgically treated group versus 5.9% in the percutaneous coronary intervention group versus 8.8% in the medically treated group). Thielmann and colleagues  came to a similar result: in-hospital and 1-year mortality rates were 12.0% and 20.0% for the percutaneous coronary intervention group, 20.0% and 27% in the surgical group, and 14.8% and 18.5% in the conservative group (p ¼ NS). In our series that included 336 patients (coronary artery bypass grafting in 294 patients and 84 valve and 14 aortic procedures) who underwent postoperative coronary angiogram, 56 patients underwent reoperation, and percutaneous coronary intervention was performed in 120 patients. After adjustment for all possible confounders reoperation was not an independent risk factor for in-hospital rates of mortality. In our opinion a surgical procedure remains a reasonable option, especially with graft-related problems (such as anastomotic occlusions or kinking). Moreover, some complications such as kinking of the graft can be solved through a fast operation without the necessity of the extracorporeal circulation. Angelo M. Dell’Aquila, MD Jan Landwehrt, MD Mirela Scherer, MD Department of Cardiothoracic Surgery University Hospital Muenster, Germany Albert-Schweitzer-Campus 1, Bldg A1 D-48149 Muenster, Germany email: [email protected]
Department of Anesthesiology & Critical Care Medicine The Johns Hopkins Hospital 1800 Orleans, Zayed 6208B Baltimore, MD 21287 email: [email protected]