Ambulatory blood pressure profiles in familial dysautonomia

Autonomic dysfunction and cardiovascular risk in post-traumatic stress disorder

BACKGROUND

Patients with post-traumatic stress disorder (PTSD) have an increased risk for cardiovascular disease. The underlying mechanisms are unclear but impaired autonomic function may contribute. However, research in this field has shown contradictory results and the causal links between PTSD, autonomic dysfunction, and cardiovascular risk remain unknown. This brief review summarizes the current knowledge on alterations in autonomic function and cardiovascular risk in patients with PTSD.

LITERATURE SEARCH STRATEGY

A PubMed search of the literature was performed using the following keywords: autonomic function, heart rate variability, blood pressure variability, sympathetic activity, baroreflex function, and cardiovascular risk in combination with PTSD. Evidence-based studies conducted between 2000 and 2021 were selected.

RESULTS

In total 1221 articles were identified and of these, 61 (48 original research papers, 13 review articles) were included in this review. Many, though not all, studies have reported increased activity of the sympathetic nervous system and decreased activity of the parasympathetic nervous system (namely, autonomic imbalance) in PTSD patients. There seems to be enough evidence to suggest impairments in baroreflex function in PTSD, leading to blood pressure dysregulation. It appears that the chronicity of PTSD diagnosis and symptom severity are independent risk factors for cardiovascular disease, which may be linked with impaired autonomic function.

CONCLUSIONS

Increased cardiovascular risk may be associated with autonomic dysfunction in PTSD. Whether autonomic dysfunction can serve as a biomarker for the onset and progression of PTSD remains to be determined. It also needs to determine if autonomic imbalance increases the risk of developing PTSD.

Early onset neurocirculatory response to static handgrip is associated with greater blood pressure variability in women with posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is a psychiatric illness that is more prevalent in women, and accumulating evidence suggests a link between PTSD and future development of cardiovascular disease. The underlying mechanisms are unclear, but augmented sympathetic reactivity to daily stressors may be involved. We measured muscle sympathetic nerve activity (MSNA), blood pressure (BP), and heart rate responses in 14 women with PTSD and 14 healthy women (controls) during static handgrip (SHG) exercise to fatigue at 40% of maximal voluntary contraction (MVC). Two minutes of postexercise circulatory arrest (PECA) was followed immediately after SHG to fatigue. MVC and the time to fatigue during SHG did not differ between groups (both P > 0.05). At the first 30 s of SHG, women with PTSD showed augmented sympathetic neural [mean ± SD, ∆MSNA burst frequency (BF): 5 ± 4 vs. 2 ± 3 bursts/30 s, P = 0.02 and ∆MSNA total activity (TA): 82 ± 58 vs. 25 ± 38 arbitrary units/30 s, P = 0.004] and pressor (∆systolic BP: 10 ± 5 vs. 4 ± 3 mmHg, P = 0.003) responses compared with controls. However, MSNA and BP responses at fatigue and during PECA were not different between groups. More interestingly, the augmented initial neural and pressor responses to SHG were associated with greater awake systolic BP variability during ambulation in women with PTSD (MSNA BF: r = 0.55, MSNA TA: r = 0.62, and SBP: r = 0.69, all P < 0.05). These results suggest that early onset exercise pressor response in women with PTSD may be attributed to enhanced mechano- rather than metaboreflexes, which might contribute to the mechanisms underlying the link between PTSD and cardiovascular risk.NEW & NOTEWORTHY The novel findings of the current study are that women with posttraumatic stress disorder (PTSD) exhibited augmented sympathetic neural and pressor responses at the first 30 s of submaximal isometric muscle contraction. More interestingly, exaggerated neurocirculatory responses at the onset of muscle contraction were associated with greater ambulatory awake systolic blood pressure fluctuations in women with PTSD. Our findings expand the knowledge on the physiological mechanisms that perhaps contribute to increased risk of cardiovascular disease in such a population.

Chemoreflex failure and sleep-disordered breathing in familial dysautonomia: Implications for sudden death during sleep

Familial dysautonomia (Riley-Day syndrome, hereditary sensory and autonomic neuropathy type III) is a rare autosomal recessive disease characterized by impaired development of primary sensory and autonomic neurons resulting in a severe neurological phenotype, which includes arterial baroreflex and chemoreflex failure with high frequency of sleep-disordered breathing and sudden death during sleep. Although a rare disease, familial dysautonomia represents a unique template to study the interactions between sleep-disordered breathing and abnormal chemo- and baroreflex function. In patients with familial dysautonomia, ventilatory responses to hypercapnia are reduced, and to hypoxia are almost absent. In response to hypoxia, these patients develop paradoxical hypoventilation, hypotension, bradycardia, and potentially, death. Impaired ventilatory control due to chemoreflex failure acquires special relevance during sleep when conscious control of respiration withdraws. Overall, almost all adult (85%) and pediatric (95%) patients have some degree of sleep-disordered breathing. Obstructive apnea events are more frequent in adults, whereas central apnea events are more severe and frequent in children. The annual incidence rate of sudden death during sleep in patients with familial dysautonomia is 3.4 per 1000 person-year, compared to 0.5-1 per 1000 person-year of sudden unexpected death in epilepsy. This review summarizes recent developments in the understanding of sleep-disordered breathing in patients with familial dysautonomia, the risk factors for sudden death during sleep, and the specific interventions that could prevent it.