Degree of influence of hypertension and type 2 diabetes on early heart rate variability after cardiac bypass surgery

Abstract:

Objective To investigate the trend of perioperative heart rate variability（HRV） in patients undergoing off-pump coronary artery bypass grafting （OPCABG），and the extent to which hypertension and/or type 2 diabetes mellitus（T2DM） factors influence this trend.Methods A retrospective study was conducted to reflect the early changes in HRV in the hospitalization of 521 patients with OPCABG from December 2020 to March 2022 who needed OPCABG for treating coronary atherosclerotic heart disease during hospitalization. According to whether the patient had previous hypertension or/and T2DM，patients were divided into four groups：A，B，C，and D. Among them，patients in group A had hypertension combined with T2DM（n=118）， patients in group B had simple hypertension （n=183），patients in group C had T2DM alone（n=81），and patients in group D had no previous hypertension and no T2DM（n=139）. An independent-samples t-test was performed on 521 patients to observe the changes of the standard deviation of NN interval（SDNN） and the root-mean-square of difference-value of adjacent RR interval（rMSSD） in the OPCABG perioperative period. At the same time，the univariate ANOVA test was performed with 4 groups of patients，and Bonferroni post hoc test was performed to explore the relationship among hypertension，diabetes and HRV.Results The time-domain indexes SDNN and rMSSD of perioperative HRV of OPCABG decreased compared with those before the operation［SDNN：（89.744±23.350） ms vs. （58.027±13.565） ms；rMSSD：（29.184±13.060） ms vs. （20.132±9.298） ms，all P<0.05）. The SDNN indexes［（51.258±10.358） ms］ in the hypertension combined with T2DM group were lower than those in the hypertension group［（59.271±11.858） ms，P<0.001］，and those were lower in hypertension combined with T2DM group［（51.258±10.358） ms］ than in the T2DM group［（55.273±9.538） ms，P=0.182］. The rMSSD index after OPCABG （20.132±9.298） was lower than that before surgery（29.184±13.061，P<0.001）.Conclusion HRV function is seriously impaired in early postoperative patients. The decline in SDNN index is most obvious in patients with prior hypertension and T2DM after OPCABG， and T2DM factor plays a greater role in the decline of HRV in the early postoperative period than hypertension，and T2DM plays a greater role in the coordination and dysfunction of sympathetic and parasympathetic nerves in the early postoperative period. The overall decline in vagus nerve function in postoperative patients，and the effects of hypertension and T2DM factors on the decline of vagus nerve function in the early postoperative period are not specific