Open sternum, cooler heart: The effect of surgical approach on myocardial temperature

摘要

Central MessageThe potential for decreased myocardial cooling in robotic mitral valve repair should be taken into consideration.See Commentaries on pages 43, 44, and 46. The potential for decreased myocardial cooling in robotic mitral valve repair should be taken into consideration. See Commentaries on pages 43, 44, and 46. We previously demonstrated del Nido solution to be a safe alternative to conventional cardioplegia in adult isolated valve surgery; however, there is little information concerning factors that might influence its effectiveness.1Mick S.L. Robich M.P. Houghtaling P.L. Gillinov A.M. Soltesz E.G. Johnston D.R. et al.del Nido versus Buckberg cardioplegia in adult isolated valve surgery.J Thorac Cardiovasc Surg. 2015; 149: 626-636Abstract Full Text Full Text PDF PubMed Scopus (89) Google Scholar Because the heart is directly exposed to a number of factors influencing temperature (eg, operative lights, ambient operating room temperature of 19°C) in a sternotomy and a robotic procedure, the heart remains predominately enclosed in the body cavity (with, perhaps, a lesser potential for radiant heat loss), we hypothesized that myocardial temperature may differ during mitral surgery performed through these approaches. We prospectively studied 50 patients who underwent isolated mitral valve repair with single antegrade dose (20 mL/kg) del Nido cardioplegia as part of a quality improvement study. A total of 25 patients underwent a median sternotomy, and 25 patients underwent robotic repair. Because of the limited exposure in robotic cases, the only cardiac structure equally accessible for measurements in both approaches was the body of the right atrium (RA). RA temperatures were collected at 7 different time points during the surgery: the start of cardiopulmonary bypass; the start of cardioplegia infusion; the conclusion of cardioplegia administration; 10, 20, and 30 minutes after aortic crossclamp; and immediately after aortic crossclamp removal. All patients were systemically cooled to 32°C with cooling started after crossclamp. Room temperature CO2 was used to flood the field in both approaches. Temperatures were collected using a noncontact infrared thermometer (Fluke 62 Max, Fluke Corp, Everett, WA) calibrated according to the manufacturer's guidelines). Topical cooling was not used in either approach. We compared temperatures between groups at these time points. Linear mixed model was fit containing main effects for surgical type, time, and a surgical type by time cross-product term using SAS statistical software (SAS version 9.2; SAS Institute, Inc, Cary, NC). Model contrast statements were used to test for differences among the surgical types for each time point. Patient characteristics and crossclamp times are shown in Table 1. Crossclamp times in robotic cases were significantly longer compared with sternotomy cases. Temperatures were higher in RCs at the end of cardioplegia administration (26.2°C vs 18.8°C, P < .0001) and at 10 minutes (27.4°C vs 22.2°C, P = .0001) and 20 minutes (27.5°C vs 23.8°C, P < .0001) after crossclamp, but equalized at 30 minutes (Figure 1).Table 1Patient characteristicsRobot (n = 25)Median sternotomy (n = 25)P valuesAge, y60.8 (±15.2)55.74 (±8.77).171Male gender19 (79.2)16 (66.7).329BMI26.12 (±2.75)26.17 (±3.86).962Body surface area (m2)1.99 (1.78-2.21)1.98 (1.82-2.14).519Crossclamp time (min)64.0 (55.75-68.75)45.5 (35.0-49.4)<.0001Data are presented as mean (±standard deviation), median (interquartile range), or number (%). BMI, Body mass index. Open table in a new tab Data are presented as mean (±standard deviation), median (interquartile range), or number (%). BMI, Body mass index. To our knowledge, this study is the first to directly assess approach-related cardiac temperature differences in patients undergoing mitral repair using del Nido solution. We found that RA temperatures decreased precipitously once single-dose cooled (4°C) del Nido solution was administered antegrade in s