[Use of glomus-sparing techniques in surgery of carotid arteries]. / Primenenie glomussberegaiushchikh tekhnik v khirurgii sonnykh arterii.

The carotid glomus is an anatomical structure located in the bifurcation of the common carotid artery and consisting of chemo and baroreceptors. It is an important reflexogenic zone participating in provision of constancy of arterial pressure. Performing eversion carotid endarterectomy is accompanied by damage of the structures of the carotid glomus, which is followed by persistent arterial hypertension in the early postoperative period. This complication remains one of the unsolved tasks in surgery of carotid arteries. The article contains a review of the literature concerning the problem of the development of postoperative arterial hypertension in patients after carotid endarterectomy carried out with skeletization of the bifurcation of the common carotid artery and with damage to the structures of the carotid glomus. Many authors report a positive effect of surgical interventions performed with preservation of the carotid body. Further studies of the results of treatment by means of glomus-sparing techniques at a longer postoperative follow-up period are required.

Baroreflex failure syndrome: a rare complication of bilateral carotid body tumor excision.

Baroreflex failure syndrome is a rare disorder seen after bilateral carotid body tumor resection. Iatrogenic injuries to the baroreceptor reflex arc cause fluctuations in blood pressure with hypertensive attacks or hypotensive episodes. A 43-year-old woman underwent bilateral carotid body tumor resection with one-week interval for a hypervascular tumor, 78 x 50 x 45 mm in size, at the right carotid artery bifurcation and a smaller tumor (50 x 30 x 20 mm) in the contralateral neck. Blood pressure of the patient became significantly unstable after excision of the second tumor, with hypertensive attacks up to 220/140 mmHg, accompanied by episodes of severe frontal headache, nausea, vomiting, skin flushing, and synchronous sinus tachycardia of 130 beats/min. Intermittent episodes of hypotension and bradycardia were also noted. The patient was clinically diagnosed as having baroreflex failure syndrome. The symptoms of the patient improved with medical therapy including clonidine, low dose beta-blocker, metoprolol, and a sedative. During 10 months of follow-up, she was generally well with residual episodes of hypertension about twice a month. In patients with bilateral carotid body tumors, unilateral excision of the greater tumor and a conservative approach for the contralateral tumor seem to be a more convenient approach to prevent baroreflex failure.

Frequency responses to hypoxia and hypercapnia in carotid body-denervated conscious rats.

The ventilatory response to brief, severe hypoxia is biphasic consisting of an initial facilitation followed by a slowing of breathing frequency (fR). After the hypoxic stimulus is removed, fR drops below baseline levels. This phenomenon is called the post-hypoxic frequency decline (phfd). These fR changes are due to reciprocal changes in expiratory time (TE), mediated by the ventrolateral pontine A5 region (J. Physiol. (London) 497 (1996) 79; Am. J. Physiol. 274 (1998) R1546). The purpose of this study was to determine if carotid body input is required for full manifestation of phfd by quantifying ventilation in intact and carotid sinus denervated rats in response to hypoxic, and contrasted with hypercapnic stimuli. Following carotid denervation the initial facilitation of fR was eliminated in response to hypoxia, but the phfd remained. In contrast the pattern in response to increased CO2 remained constant before and after carotid denervation. These results suggest that phfd is not dependent upon carotid body stimulation, but is mediated centrally.

Influence of the stimulation of central chemoreceptors on the gastric mucosal blood flow in artificially ventilated and spontaneously breathing rats.

Respiratory failure coincides frequently with the occurrence of gastric ulceration. In advanced respiratory insufficiency hypoxemia is often accompanied by hypercapnia, which is the stimulus for central chemoreceptors as well as for carotid body chemoreceptors. The purpose of the work was to investigate the reflex effect of stimulation of central chemoreceptors on gastric mucosal blood flow (GMBF) in the rat. Central chemoreceptors were stimulated by a gas mixture composed of 10% carbon dioxide, 50% oxide and 40% nitrogen. In artificially ventilated and spontaneously breathing animals, the stimulation of central chemoreceptors caused a significant increase in gastric mucosal vascular resistance, accompanied by a marked decline in blood flow. We hypothesize that in patients with respiratory insufficiency accompanied by hypercapnia, the reflex impairment of GMBF may contribute to gastric ulceration.

Poor ventilatory response to mild hypoxia may inhibit acclimatization at moderate altitude in elderly patients after carotid surgery.

Peripheral chemoreceptors (carotid bodies) are the main sensing organs for hypoxaemia. During carotid surgery, the carotic body in the bifurcation of the common carotid artery is often involved and damaged or destroyed. Animals lose their ability to adapt to high altitude after experimental denervation of the carotid bodies. The objective of our study was to evaluate the ability of human patients to adapt to moderate altitude after single side carotid surgery. Blood gas analysis at rest at 171 m and after car and cable car transport to 1600 m before and after carotid surgery was performed. Mean(s.d.) paO2 decreased insignificantly from 74.8(3.56) at 171 m altitude to 71.6(2.07) at 1600 m (P = n.s.), means(s.d.) paCO2 decreased significantly from 36.2(2.86) to 31.4(2.7) mmHg (P < 0.05) before carotid surgery. Months after surgery, a significant drop in paO2 occurred after identical passive exposure to moderate altitude: mean(s.d.) paCO2 at 171 m 74.4(3.65) mmHg, at 1600 m 65.8(3.70) mmHg (P < 0.01), paCO2 did not change significantly. Mean(s.d.) paCO2 at 171 m: 36.0(2.35), at 1600 m 36.2(2.86) mmHg (P = n.s.). Although the sample investigated was small, after single side carotid surgery patients seem to lose their ability for satisfactory ventilatory response to acute exposure to moderate altitude. This is of possible alpine medical importance.