Blood flow acceleration in the carotid and brachial arteries of healthy volunteers: respective contributions of cardiac performance and local resistance

Summary— The influence of local resistance and cardiac performance on peripheral blood acceleration was investigated in 14 healthy male volunteers. Steady and pulsatile flow was studied in the brachial and in the common carotid arteries, ie, two territories that exhibit marked differences in resistive characteristics. Instantaneous blood velocity (V), mean blood velocity (V_m) and artery diameter (D) were evaluated at rest by an ultrasonic range-gated pulsed Doppler flowmeter using a double transducer probe, thus allowing the calculation of mean blood flow (Q). Mean local resistance (R) was obtained by dividing the mean arterial pressure by Q. The peak value of the local acceleration of the blood was obtained by computer-assisted calculation of the first derivative of instantaneous blood velocity (G_max = +dV/dt_max). Peak aortic blood acceleration (GAo) was simultaneously measured from the suprasternal notch using a pulsed Doppler velocity meter. In the brachial and the common carotid arteries, G_max was of a similar magnitude (551 ±30 and 555 ± 44 cm/s², respectively) despite major differences in the respective D, V_m, Q and R values. In neither artery was there a relationship between G_max and either resting Q or R. At the brachial artery level, G_max was positively related to GAo ( r = 0.79, P = 0.0008). At the common carotid artery level, there was a weak, although non significant relationship between G_max and GAo ( P = 0.08). Our results indicate that the local acceleration of peripheral blood flow in the brachial artery is related rather to upstream central impulse than to downstream hemodynamics, and suggest some regional differences in the hemodynamic determinants of the local acceleration of peripheral blood flow.     

Acute peripheral arterial and graft occlusion: treatment with selective infusion of urokinase and lysyl plasminogen

Thirty-five patients hospitalized for recent angiographically documented arterial occlusion in the legs (27 femoropopliteal arteries and eight grafts) benefited from local fibrinolytic therapy delivered at the site of the occlusion with a 4- or 5-F catheter. This therapy combined a continuous urokinase (UK) infusion of 1,000 U/kg/hour and a lysyl plasminogen (LYS-PLG) infusion of 15 microkatals every 30 minutes. Angiographically confirmed lysis was obtained in 85% of the cases. Only 3% of the patients had major and 6% had minor groin hematomas. Only two patients had concentrations of fibrinogen as low as 100 mg/dl. Intravascular infusion of UK-LYS-PLG is as effective as streptokinase. Its excellent tolerance makes it a good alternative in the treatment of acute ischemia in the lower limbs.     

Use of new inotropic agents in the treatment of acute cardiac failure

The drugs, new and old, useful in the treatment of acute cardiac failure, are reviewed in the light of its pathophysiological mechanisms and of the biochemical aspects of myocardial contraction. Two major classes of drugs are considered, those that stimulate cell membrane adenylcyclase, i.e. beta-agonists (dopamine, dobutamine and dopexamine) and alpha-agonists (glucagon, forskolin, calcium agonists) and those that inhibit the cellular phosphodiesterases, i.e. bipyridine derivatives (amrinone and milrinone) and imidazolone derivatives (fenoximone and piroximone). Virtually, all the inotropic agents act by increasing the entry of calcium into the cell by increasing the intracellular AMPc concentration. Dopamine has a dose-related triphasic activity. At low doses, stimulation of renal dopaminergic receptors increases renal blood flow, glomerular filtration rate and sodium clearance. At moderate doses, dopamine stimulates, for the most part, cardiac beta-adrenergic receptors. Higher doses stimulate alpha-1-adrenergic receptors, with an increase in systemic arterial and venous pressures. Dobutamine exerts a potent positive inotropic action, with little effect on vascular tone and less tachycardia than with other catecholamines, resulting in only a slight increase in myocardial oxygen consumption. The dopamine analogue, dopexamine, increases renal blood flow, myocardial contractility and produces peripheral vasodilation. The haemodynamic effects of phosphodiesterase inhibitors are similar to those of dobutamine, except that these drugs are vasodilators, their positive inotropic properties are weak and their haemodynamic effects persist for at least 8 h after a single dose in heart failure patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Separation of two different populations of granulocytes of Nereis diversicolor (Annelida) by selective agglutination with lectins

Methods for obtaining coelomocyte populations from Nereis diversicolor by selective agglutination have been developed. Two main types of granulocytes have been successfully separated and recovered using respectively galactose and fucose specific lectins. 85 to 90% of the separated cells were viable.     

Segmental intestinal muscular thinning: a possible cause of intestinal obstruction in the newborn

Intestinal obstruction proximal to a transition zone without an interposed physical barrier usually indicates Hirschsprung disease. The authors report one case of focal small bowel muscular thinning just distal to a transition zone that produced clinical and radiographic findings that simulated long-segment Hirschsprung disease in a 2-day-old infant.