RESUMEN
The stimulation of the alpha(1)-adrenergic receptor by phenylephrine results in a sizable extrusion of Mg2+ from liver cells. Phenylephrine-induced Mg2+ extrusion is almost completely abolished by the removal of extracellular Ca2+ or in the presence of SKF-96365, an inhibitor of capacitative Ca2+ entry. In contrast, Mg2+ extrusion is only partially inhibited by the Ca2+-channel blockers verapamil, nifedipine, or (+)BAY-K8644. Furthermore, Mg2+ extrusion is almost completely prevented by TMB-8 (a cell-permeant inhibitor of the inositol trisphosphate receptor), 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (an intracellular Ca2+-chelating agent), or W-7 (a calmodulin inhibitor) Thapsigargin can mimic the effect of phenylephrine, and the coaddition of thapsigargin and phenylephrine does not result in an enlarged extrusion of Mg2+ from the hepatocytes. Regardless of the agonist used, Mg2+ extrusion is inhibited by >90% when hepatocytes are incubated in the presence of physiological Ca(2+) but in the absence of extracellular Na(+). Together, these data suggest that the stimulation of the hepatic alpha(1)-adrenergic receptor by phenylephrine results in an extrusion of Mg2+ through a Na(+)-dependent pathway and a Na(+)-independent pathway, both activated by changes in cellular Ca2+.
Asunto(s)
Hepatocitos/metabolismo , Magnesio/metabolismo , Receptores Adrenérgicos alfa/fisiología , Sodio/fisiología , Animales , Transporte Biológico/fisiología , Calcio/fisiología , Calmodulina/fisiología , Membrana Celular/metabolismo , Citosol/metabolismo , Retículo Endoplásmico/metabolismo , Espacio Extracelular/metabolismo , Inositol 1,4,5-Trifosfato/fisiología , Masculino , Ratas , Ratas Sprague-DawleyRESUMEN
OBJECTIVES: The study evaluated the safety and efficacy of stent reconstruction of stenotic/occluded iliofemoral veins (IFV) and inferior vena cava (IVC). BACKGROUND: Patients with congenital heart defects and stenotic or occluded IFV/IVC may encounter femoral venous access problems during future cardiac surgeries or catheterizations. METHODS: Twenty-four patients (median age 4.9 years) underwent implantation of 85 stents in 22 IFV and 6 IVC. Fifteen vessels were severely stenotic and 13 were completely occluded. Although guide wires were easily passed across the stenotic vessels, occluded vessels required puncture through the thrombosed sites using a stiff wire or transseptal needle. Once traversed, the occluded site was dilated serially prior to stent implantation. RESULTS: Following stent placement, the mean vessel diameter increased from 0.9 +/- 1.6 to 7.4 +/- 2.6 mm (p < 0.05). Twenty-one of 28 vessels had long segment stenosis/occlusion requiring two to seven overlapping stents. Repeat catheterizations were performed in seven patients (9 stented vessels) at mean follow-up of 1.6 years. Seven vessels remained patent with mean diameter of 6.4 +/- 2.0 mm. Two vessels were occluded, but they were easily recanalized and redilated. Echocardiographic follow-up in two patients with IVC stents demonstrated wide patency. In four additional patients, a stented vessel was utilized for vascular access during subsequent cardiac surgery (n = 3) and endomyocardial biopsy (n = 1). Therefore, 13 of 15 stented vessels (87%) remained patent at follow-up thus far. CONCLUSIONS: Stenotic/obstructed IFV and IVC may be reconstructed using stents to re-establish venous access to the heart for future cardiac catheterization and/or surgeries.
Asunto(s)
Angioplastia de Balón , Cateterismo Cardíaco , Vena Femoral , Vena Ilíaca , Stents , Vena Cava Inferior , Preescolar , Constricción Patológica/terapia , Femenino , Cardiopatías Congénitas/diagnóstico , Cardiopatías Congénitas/terapia , Humanos , Masculino , Resultado del TratamientoRESUMEN
The administration of selective alpha(1) (phenylephrine)-, beta (isoproterenol)-, or mixed (epinephrine) adrenergic agonists induces a marked Mg(2+) extrusion from perfused rat livers. In the absence of extracellular Ca(2+), phenylephrine does not induce a detectable Mg(2+) extrusion, isoproterenol-induced Mg(2+) mobilization is unaffected, and epinephrine induces a net Mg(2+) extrusion that is lower than in the presence of extracellular Ca(2+) and quantitatively similar to that elicited by isoproterenol. In the absence of extracellular Na(+), no Mg(2+) is extruded from the liver irrespective of the agonist used. Similar results are observed in perfused livers stimulated by glucagon or 8-chloroadenosine 3', 5'-cyclic monophosphate. In the absence of extracellular Na(+) or Ca(2+), adrenergic-induced glucose extrusion from the liver is also markedly decreased. Together, these results indicate that liver cells extrude Mg(2+) primarily via a Na(+)-dependent mechanism. This extrusion pathway can be activated by the increase in cellular cAMP that follows the stimulation by glucagon or a specific beta-adrenergic receptor agonist or, alternatively, by the changes in cellular Ca(2+) induced by the stimulation of the alpha(1)-adrenoceptor. In addition, the stimulation of the alpha(1)-adrenoceptor appears to activate an auxiliary Ca(2+)-dependent Mg(2+) extrusion pathway. Finally, our data suggest that experimental conditions that affect Mg(2+) mobilization also interfere with glucose extrusion from liver cells.
Asunto(s)
8-Bromo Monofosfato de Adenosina Cíclica/análogos & derivados , Calcio/farmacología , Hepatocitos/metabolismo , Magnesio/metabolismo , Receptores Adrenérgicos alfa 1/metabolismo , Receptores Adrenérgicos beta/metabolismo , Sodio/farmacología , 8-Bromo Monofosfato de Adenosina Cíclica/farmacología , Agonistas Adrenérgicos/farmacología , Inhibidores de Captación Adrenérgica/farmacología , Agonistas alfa-Adrenérgicos/farmacología , Agonistas Adrenérgicos beta/farmacología , Amilorida/farmacología , Animales , Diuréticos/farmacología , Epinefrina/farmacología , Glucagón/farmacología , Glucosa/metabolismo , Hepatocitos/química , Hepatocitos/efectos de los fármacos , Imipramina/farmacología , Isoproterenol/farmacología , Hígado/citología , Hígado/metabolismo , Masculino , Fenilefrina/farmacología , Floretina/farmacología , Ratas , Ratas Sprague-Dawley , Estimulación QuímicaRESUMEN
We present a 1,600 g infant who underwent successful balloon aortic valvuloplasty from the right carotid artery approach. A simple technique to facilitate access to the left ventricle and expedite the procedure is described. Issues unique to performing balloon aortic valvuloplasty on such a small child are discussed.
Asunto(s)
Estenosis de la Válvula Aórtica/terapia , Cateterismo/métodos , Enfermedades del Prematuro/terapia , Recien Nacido Prematuro , Humanos , Recién Nacido de Bajo Peso , Recién NacidoRESUMEN
Patients with unrepaired pulmonary artery atresia and ventricular septal defect (PA/VSD) depend on aortoplumonary collaterals and surgically created shunts for pulmonary blood flow. These vessels frequently develop stenoses with time, leading to hypoperfusion of lung segments and systemic hypoxemia. The purpose of this article is to describe catheter palliation of hypoxemic patients with PA/VSD who were not candidates for surgical repair. We present our experience with stent implantation for stenosis of aortopulmonary collaterals and shunts in these patients. Three patients with hypoplastic pulmonary arteries underwent stent placement in aortopulmonary collateral arteries (APCAs) or their shunts. Technical aspects of the interventional catheterization procedure are discussed in detail. Case 1 underwent placement of five stents in collateral vessels and one stent in the Blalock-Taussig shunt (BT) with dramatic increase in vessel size and improvement in saturations from 70% to 89%. Case 2 underwent placement of two overlapping stents in a collateral vessel with an increase in diameter of the collateral vessel from 2.3 to 6 mm and an improvement in saturation from 68% to 88%. Case 3 underwent placement of three overlapping stents in a BT shunt with an increase in diameter of the shunt from 2.2 to 6.6 mm and an improvement in saturation from 71% to 89%. All three patients had excellent clinical improvement and stable saturation at follow-up. Stent placement for maintaining patency of APCAs and aortopulmonary shunts is feasible and safe.
Asunto(s)
Defectos del Tabique Interventricular/terapia , Pulmón/irrigación sanguínea , Cuidados Paliativos , Atresia Pulmonar/terapia , Stents , Adulto , Angiografía , Niño , Circulación Colateral/fisiología , Constricción Patológica/diagnóstico por imagen , Constricción Patológica/terapia , Síndrome de DiGeorge/diagnóstico por imagen , Síndrome de DiGeorge/terapia , Femenino , Defectos del Tabique Interventricular/diagnóstico por imagen , Humanos , Hipoxia/diagnóstico por imagen , Hipoxia/terapia , Masculino , Arteria Pulmonar/anomalías , Arteria Pulmonar/diagnóstico por imagen , Atresia Pulmonar/diagnóstico por imagenRESUMEN
Postoperative bradycardia is not uncommon following the Fontan procedure in patients with a functional single ventricle. The surgical connections created with various Fontan modifications may complicate access to the atria for transvenous implantation of a permanent pacemaker. We describe approaches to overcoming problems with atrial access in an adolescent with complex congenital heart disease who required permanent transvenous atrial pacing for tachycardia-bradycardia after Fontan surgery.