The Effect of Successful Heart Transplant Treatment of Heart Failure on Central Sleep Apnea: Materials and Methods
Subjects and Protocol
Patients with a diagnosis of ischemic or idiopathic cardiomyopathy, and selected for heart transplantation assessment were included in the study. Patients with congenital, valvular, or restrictive heart disease were excluded. All patients were optimally treated and considered medically stable at the time of heart transplantation assessment.
At the time of heart transplantation assessment, patients underwent Tc radionucleotide equilibrium measurement of left ventricular ejection fraction (LVEF), overnight polysomnography, and measurement of sympathetic nerve activity with overnight urinary norepinephrine excretion (UNE). Patients with plasma creatinine level of > 180 mmol/L were not included. Here
Patients with CSA who subsequently underwent successful heart transplantation were re-evaluated for the presence of sleep-disordered breathing (SDB) at a minimum of 6 months after transplantation. A group of patients with severe CHF and no SDB who also underwent successful heart transplantation with repeat overnight polysomnography at a minimum of 6 months after transplantation and were matched for posttransplant medical therapy, served as a control group. All patients were in stable condition and had maintained normal function of the heart allograft. The study was approved by the Alfred Hospital Ethics Committee, and all patients provided written informed consent.
Full overnight polysomnography was performed using a computerized system (Somnostar; SensorMedics; Yorba Linda, CA). Sleep staging was determined manually by monitoring with two-channel EEG, two-channel electrooculogram, and submental electromyogram. Oronasal airflow was monitored by thermistor (ProTech Services; Woodinville, WA). Thoracoabdominal movement was recorded using calibrated respiratory effort bands (Resp-ez; EPM Systems; Midlothian, VA). ECG recorded heart rate and rhythm from lead II. Pulse oximetric saturation (Spo2) was monitored using ear probe pulse oximetry (Fastrac; Sensor-Medics).