Intra-Arterial Labetalol and Nitroglycerin in Preventing Radial Artery Spasm Following Transradial Angiography: A New Approach

Background: Radial artery spasm (RAS) resulted from decreasing blood flow and activation of vasomotor system leads to a decrease in artery diameter, perfusion and patency, and increase the risk of procedure failure. In this study, we investigated the effects of intra-arterial administration of nitroglycerin and labetalol on radial artery diameter, RAS, and pain intensity in patients undergoing diagnostic radial angiography. Methods: Sixty-four patients randomly enrolled into one of the nitroglycerin (150 μg) or labetalol (500 μg) groups. The radial artery size, and the incidence of RAS were measured before, immediately after puncture, and at the end of treatment. Pain intensity was evaluated using a visual-analog-scale (VAS) at the end of the procedure. Hemodynamic status before, and during the procedure was also recorded. Results: Labetalol causes a significantly larger increase in radial diameter than nitroglycerin immediately after intra-arterial injection (2.24±0.58 mm vs. 1.65±0.39 mm, P-value<0.001). The rate of RAS immediately after vasodilator administration in the labetalol group was 3.1% vs. 12.5% in the nitroglycerin group (P-value=0.355), but the overall incidence (immediately after administration+ at the end of procedure) did not show a statistically significant difference (53.125% vs 31.25% respectively, P-value=0.076). The VAS score did not show a significant difference between two groups (1.15±0.44 in nitroglycerin vs. 1.50±0.91, P-value=0.063). Conclusion: Labetalol increases radial artery diameter more than nitroglycerin. However, the efficacy of labetalol in terms of RAS incidence, and patients’ pain was similar to nitroglycerin. Therefore, intra-arterial labetalol could be considered as one of the therapeutic options in clinical practice in order to reduce RAS and procedure failure.

Role of the Suprachiasmatic Nucleus in the Pathogenesis of Migraine Attacks

Neuroanatomic, morphometric, immunocytochemical, neurobiochemical and clinical data support the hypothesis that the suprachiasmatic nucleus of the hypothalamus might be the initial site of migraine attacks. The prodromal phase of a migraine attack could be considered a syndrome of functional suprachiasmatic nucleus insufficiency, and other phases a reactive denervation hypersensitivity with the affection of the visual, nociceptive, antinoacceptive and cranial vasomotor system.

Peripheral Vascular and Sweat-Gland Reflexes in Diabetic Neuropathy

1. In two groups of diabetic patients, one with and one without signs of peripheral neuropathy, reflex short vasoconstrictor responses to such stimuli as a cough, a sharp inspiration or sudden noise were recorded from a finger and both big toes by volume plethysmography. Simultaneous electrodermal responses to the same stimuli were recorded from a hand and a foot. Vasodilator responses to body warming were also recorded. 2. Significant impairment of these vasomotor reflexes in diabetic patients with neuropathy indicates that the sympathetic vasomotor system can be involved in diabetic peripheral neuropathy. 3. Loss of the reflex electrodermal responses is also evidence of impairment of another sympathetic function in such patients. 4. Because stimuli vary in their effectiveness in causing responses in both groups of subjects, it is suggested that changes of central nervous conductivity also occur in diabetes.

An accessory organ of the circulatory system in Sepia and Loligo

SUMMARYAn accessory organ of the circulatory system has been found in Sepia officinalis and Loligo forbesi, situated on the inner surface of the mantle around the posterior pallial vessels. It is spheroidal in shape and consists chiefly of muscle fibres forming bundles anastomosing with one another, most of them taking a general circular course round the artery and the vein. In Sepia the muscle bundles are more loosely arranged, being imbedded in connective tissue of soft consistency; they are not continuous either with the musculature of the vessels or with that of the mantle, and show certain structural differences from them. The nerves approaching this organ from various directions carry elements of two systems: (a) fibres given off by the branches innervating the neighbouring mantle muscles; (b) elements of the vasomotor system; these are 3 trunks consisting of fibres of small calibre and containing groups or rows of ganglion cells. One of these trunks associates with one of the main mantle nerves, another runs through the retractor muscle of the branchia. Within the accessory organ they intermingle with the motor fibres, but the nerve bundles passing to the posterior pallial vessels consist of fibres of the vasomotor system only; it is possible that the muscles of the accessory organ are supplied, in addition to their motor innervation, with fibres of the vasomotor system.