Topical Vasodilators for Preventing Radial Artery Spasm during Harvesting for Coronary Revascularization: Comparison of 4 Agents

Microsurgical anatomy of the maxillary artery for extracranial-intracranial bypass in the pterygopalatine segment of the maxillary artery

The extracranial-intracranial (EC-IC) bypass using the maxillary artery (MA) has been successfully completed using a radial artery (RA) graft but the complicated anatomy and narrow exposure make it difficult. The purpose of this article is to define the microsurgical exposure of the MA through the middle fossa and describe the branches, diameter, and length of the MA available for the EC-IC bypass in the sphenopalatine fossa and anterior part of the infratemporal fossa. 5 cadaveric specimens were dissected bilaterally (10 MA dissections) to define the microsurgical anatomy of the MA through an intracranial approach. The exposable branches of the MA at the level of the infratemporal and sphenopalatine fossae were the anterior deep temporal, posterior superior alveolar, and infraorbital arteries. The origin of each branch could be exposed. The available section of the MA for use as a donor vessel is between the origin of the anterior deep temporal artery and the infraorbital artery. The mean exposable length of the MA was 19.4 mm. The mean outer diameter of the donor MA was 3.2 mm. Tension-free EC-IC bypass was possible using a RA graft between the MA and the middle cerebral artery, the MA and the supraclinoid internal carotid artery (ICA), or the MA and the petrous ICA. Exposure of the MA at the infratemporal and sphenopalatine fossae is complicated but provides length and diameter suitable as a donor artery for the EC-IC bypass. Clin. Anat. 31:724-733, 2018. © 2017 Wiley Periodicals, Inc.

Taurine relaxes human radial artery through potassium channel opening action

The vascular actions and mechanisms of taurine were investigated in the isolated human radial artery (RA). RA rings were suspended in isolated organ baths and tension was recorded isometrically. First, a precontraction was achieved by adding potassium chloride (KCl, 45 mM) or serotonin (5-hydroxytryptamine, 5-HT, 30 µM) to organ baths. When the precontractions were stable, taurine (20, 40, 80 mM) was added cumulatively. Antagonistic effect of taurine on calcium chloride (10 µM to 10 mM)-induced contractions was investigated. Taurine-induced relaxations were also tested in the presence of the K⁺ channel inhibitors tetraethylammonium (1 mM), glibenclamide (10 µM) and 4-aminopyridine (1 mM). Taurine did not affect the basal tone but inhibited the contraction induced by 5-HT and KCl. Calcium chloride-induced contractions were significantly inhibited in the presence of taurine (20, 40, 80 mM) (p<0.05). The relaxation to taurine was inhibited by tetraethylammonium (p<0.05). However, glibenclamide and 4-aminopyridine did not affect taurine-induced relaxations. Present experiments show that taurine inhibits 5-HT and KCl-induced contractions in RA, and suggest that large conductance Ca²⁺-activated K⁺ channels may be involved in taurine-induced relaxation of RA.

Cutaneous analgesia before transradial access for coronary intervention to prevent radial artery spasm

Aim:

Transradial access (TRA) for coronary intervention is increasingly used in current clinical practice. The aim of the present study was to evaluate the hypothesis that cutaneous analgesia before TRA for coronary intervention at a puncture site 30 minutes before puncture can reduce patient discomfort and the incidence of radial artery spasm (RAS).

Methods:

Patients (n=104) undergoing planned coronary interventions using TRA were prospectively randomized to receive either 1 mL of 1% lidocaine subcutaneously (n=52) (control group) or subcutaneous lidocaine plus 5% lidocaine cream (n=52) cutaneously 30 minutes before puncture (treatment group). The primary endpoint was angiographically or clinically confirmed RAS. Secondary endpoints were the occurrence of patient discomfort in the forearm during the procedure and access-site crossover to the femoral artery. Patient discomfort was quantified with a visual analogue scale (VAS) score.

Results:

Fifty-two patients in the treatment group (60.5±9.4 years of age and 16 female) and 52 patients in the control group (60.4±9.7 years of age and 16 female) were included in the final analysis. Radial artery spasm occurrence decreased in the treatment group compared to the control group (26.9% vs 9.6%; p=0.04) accompanied by a VAS score of 3.7±1.8 in the treatment group and 4.9±2.0 in the control group; p=0.02. The access site crossover rate did not differ between the groups (7.6% vs 21.1%; p=0.09).

Conclusion:

Cutaneous analgesia before TRA for coronary interventions is associated with a substantial reduction in the RAS and the procedure-related level of patient discomfort.

Evaluation of iloprost to prevent vasospasm in coronary artery bypass grafts

This study assessed the efficacy of iloprost in relieving vasospasm in coronary artery bypass grafts. Radial artery (RA), left internal thoracic artery (LITA) and saphenous vein (SV) grafts were taken from 20 patients (13 men and seven women, mean age 63.8 years [range 48-74 years]) scheduled to undergo coronary artery bypass grafting. Ten 3 mm vascular rings were cut from each graft and kept under tension for at least 60 min. They were kept alive with 37 degrees C oxygenated Krebs solution. Smooth muscle contraction was achieved with phenylephrine before iloprost was administered every 2 min, starting at a concentration of 10(-9) mol/l and increasing in logarithmic increments to a concentration of 10(-5) mol/l. The vasodilation response to iloprost started in all samples at a concentration of 10(-9) mol/l and increased with each incremental increase in iloprost concentration up to 10(-5) mol/l. These data suggest that local administration of iloprost has a role in relieving graft vasospasm during harvesting and preparation for coronary artery bypass grafting.

Age deteriorates palmar microcirculation following radial artery harvesting

The effect of age as a risk factor for deterioration of palmar microcirculation after radial artery harvesting for coronary revascularization is unknown. In 114 patients aged 61.7 +/- 6.7 years undergoing radial artery harvesting, superficial and deep tissue oxygen saturation, postcapillary venous filling, and capillary blood flow were determined using a combined laser Doppler spectrophotometry system 25 +/- 5 months after surgery. Superficial and deep oxygen saturation at the harvested thenar eminence decreased with age. In the nondonor hand, oxygen saturation declined in the first and second digits. Postcapillary venous filling pressure in both thenars increased with age. It was concluded that neurological complications do not correlate with age. Palmar tissue oxygen saturation, palmar capillary blood flow, and blood velocity decrease, while postcapillary venous filling pressure significantly increases with age. Radial artery harvesting for coronary revascularization does not compromise palmar microcirculation to the same extent as age. A cut-off value of <or= 67 years was determined by microcirculatory assessment; beyond this, significant deterioration of palmar microcirculation is more likely to occur.