Peripheral sensory and cardiovascular autonomic dysfunction in kidney transplant patients

Introduction: Kidney transplantation (KTx) is the preferred treatment for end-stage renal disease. Patients with chronic kidney disease (CKD) have an increased risk for arrhythmias and sudden cardiac death. The autonomic nervous system dysfunction seems to participate in the arrhythmogenic process. Limited information is available on peripheral sensory neural impairment, cardiovascular autonomic dysfunction and QT interval variability abnormalities following successful kidney transplantation. The present study aimed to assess the peripheral and autonomic neuronal functions in transplanted patients and to compare it to age- and sex-matched healthy controls. Subjects and methods: Our study involved 23 KTx patients. The control group consisted of 19 age- and gender-matched healthy individuals. All KTx patients and healthy controls successfully underwent a 10-minute 12-lead ECG for repolarization parameter analysis, 5 standard Ewing tests for evaluation of the cardiovascular autonomic neuropathy and a complex peripheral neuronal testing. Results: According to the Ewing tests, the heart rate response to deep breathing (controls vs. KTx patients: 21.21 +/- 6.93 vs. 16.7 +/- 5.89 beats/min, p = 0.045), the heart rate response to standing up (30/15 ratio controls vs. KTx patients: 1.20 +/- 0.15 vs. 1.07 +/- 0.16, p = 0.007), and the systolic blood pressure response to standing up (controls vs. KTx patients: 4.63 +/- 6.07 vs. 12.26 +/- 13.66 mmHg, p = 0.022) were significantly impaired in the KTx patients. Significant differences could be demonstrated in the peripheral sensory function of peroneal and median nerves at all three tested frequencies with Neurometer (R). At the median nerve the sensory testing revealed increased perception thresholds compared to controls (controls versus KTx patients at 2 kHz: 157.8 +/- 61.5 vs. 278.3 +/- 84.35, p < 0.001, at 250 Hz 48.0 +/- 42.56 vs. 112.2 +/- 91.12, p = 0.005, at 5 Hz 28.95 +/- 23.14 vs. 77.96 +/- 71.24, p = 0.004, respectively). The parameters of the peroneal nerves were also significantly elevated (controls versus KTx patients at 2 kHz: 288.6 +/- 98.22 vs. 453.4 +/- 175.9, p < 0.001, at 250 Hz: 156.8 +/- 82.89 vs. 262.3 +/- 168.9, p = 0.013, on 5 Hz 82.0 +/- 58.97 vs. 142.5 +/- 129.4, p = 0.053, respectively). The application of Neuropad (R)-test, Tiptherm (R), Monofilament (R), and Rydel-Seiffer tuning fork did not reveal significant differences between KTx patients and controls. The repolarization parameters of KTx patients and controls were similar. Conclusions: Cardiovascular autonomic dysfunction and peripheral sensory neural impairment were detected in KTx patients compared to healthy volunteers. A prospective follow-up of this population and a cross-sectional study with controls suffering in CKD without kidney transplantation are planned to evaluate a possible protective function of the successful kidney transplantation.

Automated summary

Cardiovascular autonomic dysfunction and peripheral sensory neural impairment were found to be common among kidney transplant patients. Long-term follow-up is required to evaluate the protective effect of kidney transplantation on these issues.