Aortic dilation in adults with repaired tetralogy of Fallot: a single-centre study.

BACKGROUND: Tetralogy of Fallot is the most prevalent cyanotic CHD. With the advent of advanced surgical methods, the majority of tetralogy of Fallot patients reach adulthood. However, many need re-intervention for the residual anomalies including residual right ventricular outflow obstruction, pulmonary regurgitation, residual ventricular septal defects, and progressive aortic dilatation. Aortic dilation could lead to aortic regurgitation or dissection requiring surgical correction. In the current study, we aimed to determine the prevalence and outcomes of aortic root dilatation in adults with repaired tetralogy of Fallot in our tertiary care centre. METHODS: In this retrospective study, 730 consecutive patients with history of repaired tetralogy of Fallot were included. Aortic diameter at the level of annulus, the sinus of Valsalva, sinotubular junction, and the ascending aorta as measured by echocardiography were evaluated. Prevalence of outcomes necessitating re-intervention including aortic regurgitation and dissection were recorded. RESULTS: The mean size of annulus, sinus of Valsalva, sinotubular-junction, and ascending aorta in the latest available echocardiography of patients were 2.4+/-0.4 cm, 3.3+/-0.5 cm, 2.9+/-0.5cm, and 3.2+/-0.5cm, respectively. Prevalence of dilatation of sinus of Valsalva, dilation of Ascending aorta, sinotubular-junction, and aortic annulus was 28.7%, 21%, 8.3%, and 1 %, respectively. Five patients had severe aortic regurgitation (0.6%) and underwent surgical repair. One of these patients presented with acute aortic dissection. CONCLUSION: Aortic dilation is common in tetralogy of Fallot but prevalence of redo surgery for aortic dilation, regurgitation, and adverse events including acute dissection is low.

Intra-accumbal orexinergic system contributes to the stress-induced antinociceptive behaviors in the animal model of acute pain in rats.

Stress and pain are interleaved at numerous levels - influencing each other. Stress can increase the nociception threshold in animals, long-known as stress-induced analgesia (SIA). Orexin is known as a neuropeptide that modulates pain. The effect of stress on the mesolimbic system in the modulation of pain is known. The role of the intra-accumbal orexin receptors in the modulation of acute pain by forced swim stress (FSS) is unclear. In this study, 117 adult male albino Wistar rats (270-300 g) were used. The animals were unilaterally implanted with cannulae above the NAc. The antagonist of the orexin-1 receptor (OX1r), SB334867, and antagonist of the orexin-2 receptor (OX2r), TCS OX2 29, were microinjected into the NAc in different doses (1, 3, 10, and 30 nmol/0.5 µl DMSO) before exposure to FSS for a 6-min period. The tail-flick test was carried out as an assay nociception of acute pain, and the nociceptive threshold [tail-flick latency (TFL)] was measured for 60-minute. The findings demonstrated that exposure to acute stress could remarkably increase the TFLs and antinociceptive responses. Moreover, intra-accumbal microinjection of SB334867 or TCS OX2 29 blocked the antinociceptive effect of stress in the tail-flick test. The contribution of orexin receptors was almost equally modulating SIA. The present study's findings suggest that OX1r and OX2r within the NAc modulate stress-induced antinociceptive responses. The intra-accumbal microinjection of orexin receptors antagonists declares inducing antinociceptive responses by FSS in acute pain. Proposedly, intra-accumbla orexinergic receptors have a role in the development of SIA.

The stress-induced antinociceptive responses to the persistent inflammatory pain involve the orexin receptors in the nucleus accumbens.

Stress suppresses the sense of pain, a physiological phenomenon known as stress-induced analgesia (SIA). Brain orexin peptides regulate many physiological functions, including wakefulness and nociception. The contribution of the orexinergic system within the nucleus accumbens (NAc) in the modulation of antinociception induced by forced swim stress (FSS) remains unclear. The present study addressed the role of intra-accumbal orexin receptors in the antinociceptive responses induced by FSS during the persistent inflammatory pain model in the rat. Stereotaxic surgery was performed unilaterally on 106 adult male Wistar rats weighing 250-305 g. Different doses (1, 3, 10, and 30 nmol/ 0.5 µl DMSO) of orexin-1 receptor (OX1r) antagonist (SB334867) or OX2 receptor antagonist (TCS OX2 29) were administered into the NAc five minutes before exposure to FSS for a 6-min period. The formalin test was carried out using formalin injection (50 µl; 2.5%) into the rat's hind paw plantar surface, which induces biphasic pain-related responses. The first phase begins immediately after formalin infusion and takes 3-5 min. Subsequently, the late phase begins 15-20 min after formalin injection and takes 20-40 min. The findings demonstrated that intra-accumbal microinjection of SB334867 or TCS OX2 29 attenuated the FSS-induced antinociception in both phases of the formalin test, with the TCS OX2 29 showing higher potency. Moreover, the effect of TCS OX2 29 was more significant during the early phase of the formalin test. The results suggest that OX1 and OX2 receptors in the NAc might modulate the antinociceptive responses induced by the FSS.