Lignocaine: effects on coronary blood flow in patients with recent myocardial infarction.

Abstract

The myocardial clearance of rubidium may be obtained by praecordial counting after a single intravenous injection of Rb86Cl The following study uses this isotopic method, and examines the effects of lignocaine on the coronary blood flow in patients with recent myocardial infarctions. MethodsThe praecordial counting was performed with a 5 x 5 cm NaI(Ti) scintillation detector with a lead collimator, I50 mm long with an external diameter I10 mm. Pulses from the detector were fed via a pulse height analyser to a digital ratemeter and then to a recorder. For 131I activity the pulse height analyser was set for the 364 KeV photopeak with a ioo KeV window. For 86Rb, the pulse height analyser was set for i o8 MeV with a I00 KeV window. The ratemeter time constant was set at 4 seconds for recording background and at 4 seconds during the procedures. The chart speed was set at 3 cm per minute. Blood activity was measured in a 5 cm welltype scintillation detector with the pulse height analyser setting as described for external counting of 131I and 86Rb.The counts are corrected for the relative inefficiencies in the in vivo and in vitro systems, introducing a coefficient in calculated from the counting rates obtained when two soo-ml flasks containing known concentrations of 131I and 86Rb are counted externally under a standard geometrical arrangement.-(c.p.m./ml) 131I (well) xc.p.m. 86Rb(flask) n (c.p.m./ml) 86Rb (well) x c.p.m. 131I (flask) .... (I) Experimental procedureThe experiments were performed in the morning on resting subjects in the supine position. A Cournand

Vasodilatory Effects of Lidocaine on Epicardial Porcine Coronary Arteries

“…Species specificity may explain some of the differences in observed vasoactivity. Lidocaine has been found to produce vaso constriction in dogs [13] but vasodilation in humans [2]. Differences in the concentration of lidocaine achieved in the blood may also explain the conflicting results of previous studies as our data suggest that a biphasic vasoconstriction-vasodilation may occur at low and high lidocaine levels, respectively.…”

“…We have observed intravenous lidocaine (1.5-4.0 mg/ kg) to produce large increases in coronary blood flow in open-chest swine in our labo ratory [1]; others have observed similar ef fects in patients with recent myocardial in farction [2], Lidocaine has been shown to produce systemic arterial vasodilation in dogs [3] and man [4] over a wide dose range, and the coronary flow effects have been pos tulated to result from drug-induced systemic vasodilation, with secondary reflex tachy cardia and an associated increase in myo cardial oxygen consumption. Gould et al [2] questioned this observation, however, after measuring coronary blood flow by ru bidium clearance in men before and after lidocaine injection.…”

“…Other in vivo studies have indicated that lidocaine either produces va soconstriction [11,12] or no vascular effect at all [4,13]. Gould et al [2] demonstrated that lidocaine increased coronary blood flow as assessed by serial rubidium clearance measurements in men before and after lido caine injection.…”

“…Some in vivo studies have demonstrated that lidocaine produces vasodilation, as indicated by an increase in peripheral arterial blood flow [3,11] and an increase in coronary arterial blood flow [1,2]. Other in vivo studies have indicated that lidocaine either produces va soconstriction [11,12] or no vascular effect at all [4,13].…”

Glycosaminoglycan Changes in Healing Myocardial Infarction

“…Hyaluronidase may influence healing by affecting glycosaminoglycan metabolism. The lidocaine used during the surgical part of this work may have influenced the size of the injury as suggested by Gould et al (13), however, it seems unlikely that it had an effect on the healing following the injury. Furthermore, structure and composition of injured areas were compared with uninjured areas from the same heart, consequently, the differences found cannot be due to the effects of lidocaine.…”