Heart rate variability arterial hypertension in young heart-transplanted recipients: association progression of cardiac allograft vasculopathy?

Masked Hypertension in Pediatric Heart Transplant Recipients

BACKGROUND

Masked hypertension (HTN), especially, isolated nocturnal HTN (INH) has been shown to be a risk factor for cardiovascular disease (CVD) but is not studied well in pediatric heart transplant (PHT) patients. Ambulatory blood pressure monitoring (ABPM) is known to identify patients with HTN but is not used routinely in PHT.

METHODS

A single-center, prospective, cross-sectional study of PHT recipients was performed to observe the incidence of masked HTN using 24-h ABPM. The relationship between ABPM parameters and clinical variables was assessed using Spearman correlation coefficient. p value < 0.05 was considered significant.

RESULTS

ABPM was performed in 34 patients, mean age 14 ± 5 years, median 5.5 years post-PHT. All patients had normal cardiac function, left ventricular mass index and blood pressure measurements in the clinic. Four patients had known prior HTN and on medications, one of them was uncontrolled. Of the remaining 30 patients, 18 new patients were diagnosed with masked HTN, of which 14 had INH. Diurnal variation was abnormal in 82% (28/34) patients. 24-h diastolic blood pressure (DBP) index correlated with glomerular filtration rate (GFR) (r = - 0.44, p = 0.01). There was no correlation between other ABPM parameters with tacrolimus trough levels.

CONCLUSIONS

ABPM identified masked HTN in 60% of patients, with majority being INH. Abnormal circadian BP patterns were present in 82% and an association was found between GFR and DBP parameters. HTN, especially INH, is under-recognized in PHT recipients and ABPM has a role in their long-term care.

Measures of and changes in heart rate variability in pediatric heart transplant recipients

Heart rate variability is primarily regulated by the autonomic nervous system. Heart transplant recipients undergo surgical denervation of the graft, which results in interruption of autonomic innervation with resultant diminished heart rate variability although some degree of autonomic control may return. This study aimed to characterize heart rate variability in this population. We report a retrospective review of Holter monitor data from transplanted patients between 2005 and 2013. Studies with significant atrial or ventricular arrhythmias were excluded. We evaluated changes over time and compared standard time domain measures to published pediatric normal values. Data were reviewed from 582 monitors in 152 patients. We found that pediatric heart transplant recipients have lower heart rate variability than age-matched controls and higher average heart rate in recipients older than 3 years. There is an increase in measures of variability through the first 3 years post-transplant with plateau after that time. Surgical technique in regard to interruption of the vagus nerve does not affect variability, nor does underlying congenital vs acquired heart disease.

Visualization of Heart Rate Variability of Long-Term Heart Transplant Patient by Transition Networks: A Case Report

We present a heart transplant patient at his 17th year of uncomplicated follow-up. Within a frame of routine check out several tests were performed. With such a long and uneventful follow-up some degree of graft reinnervation could be anticipated. However, the patient's electrocardiogram and exercise parameters seemed largely inconclusive in this regard. The exercise heart rate dynamics were suggestive of only mild, if any parasympathetic reinnervation of the graft with persisting sympathetic activation. On the other hand, traditional heart rate variability (HRV) indices were inadequately high, due to erratic rhythm resulting from interference of the persisting recipient sinus node or non-conducted atrial parasystole. New tools, originated from network representation of time series, by visualization short-term dynamical patterns, provided a method to discern HRV increase due to reinnervation from other reasons.