Investigation of heart rate variability of patients undergoing coronary artery bypass grafting (CABG)

Investigation of heart rate variability of patients undergoing coronary artery bypass grafting using the statistical signal characterization method

BACKGROUND

Autonomic function can be estimated non-invasively using heart rate variability (HRV). HRV of patients undergoing coronary artery bypass grafting (CABG) is investigated in time-domain and frequency-domain before and after CABG to study the effect of operation on the status of patients.

OBJECTIVE

The main purpose of this work is to evaluate the effect of CABG surgery on patients with ischemic heart disease (IHD) before operation, and to monitor the status of patients on day 6 and day 30 after the CABG operation.

METHODS

The statistical signal characterization (SSC) technique is used in this work in order to derive different morphology-based parameters to indirectly describe time-domain and frequency-domain HRV parameters in 24 patients undergoing CABG operation, before the operation (Group 1: G1), 6 days after operation (Group 2: G2) and 30 days after operation (Group 3: G3). The data is obtained from the Sultan Qaboos University Hospital in Oman.

RESULTS

The SSC parameters Mean(mt) and Mean(dt) are reduced in all 24 patients and in 23 out of 24 patients in G2 compared to G1 (6-days after operation compared with before operation), respectively. Comparing G3 to G1 the reduction in Mean(mt) and Mean(dt) is noted in 18 of the 24 patients.

CONCLUSIONS

The parameters Mean(mt) and Mean(dt) are successful parameters to follow the HRV for patients undergoing CABG surgery. A relation between those SSC parameters and the HRV time-domain and frequency-domain parameters is investigated in this paper to understand the physiological behavior of the patients.

Moderate-to-high intensity inspiratory muscle training improves the effects of combined training on exercise capacity in patients after coronary artery bypass graft surgery: A randomized clinical trial

BACKGROUND

The effects of adding moderate-to-high intensity inspiratory muscle training (IMT) to short-term aerobic and resistance exercise (combined training [CT]), after coronary artery bypass grafting (CABG) are not established. This study aimed to determine the effects of moderate-to-high intensity IMT + CT on exercise capacity, respiratory muscle strength, inspiratory muscle endurance, quality of life (QoL), and laboratory biomarkers in patients after CABG who were participants of a phase II cardiac rehabilitation program.

METHODS

Twenty-four patients were randomly assigned to either the IMT + CT group (n = 12), who performed moderate-to-high intensity IMT with CT or the sham-IMT + CT group (n = 12). Patients completed two sessions per week for 12 weeks. Each patient underwent a cardiopulmonary exercise test, six-minute walk test (6MWT), respiratory muscle strength and endurance evaluation, QoL questionnaire, and serum advanced oxidation protein products, ferric reducing antioxidant power [FRAP], nitrate/nitrate, and high-sensitivity C-reactive protein, before and after the 12-week intervention.

RESULTS

The IMT + CT group showed significantly greater improvements in peak oxygen uptake (1.3 mL∙kg^-1∙min^-1; 95% confidence interval [95% CI], 0.5 to 2.2), distance covered during the 6MWT (78.8 m; 95% CI, 28.1 to 129.5), maximal inspiratory pressure (23.0 cmH₂O; 95% CI, 9.3 to 36.7), QoL (-15.1 points; 95% CI, -26.9 to -3.3), and FRAP (83.7 μmol/L; 95% CI, 20.2 to 147.1) compared to the sham-IMT + CT group as a result of the intervention.

CONCLUSIONS

Short-term moderate-to-high intensity IMT with CT provided additional benefits in exercise capacity, inspiratory muscle strength, QoL, and antioxidant profile in patients after CABG. Trial Registration clinicaltrials.gov Identifier: NCT02885077.