RESUMEN
OBJECTIVE: To determine whether a correlation exists between concentrations of intracellular and extracellular potassium and to determine the frequency of ventricular ectopy in patients after cardiac operations. DESIGN: Prospective, observational clinical evaluation. SETTING: Surgical-respiratory intensive care unit of a university-affiliated tertiary care center. PATIENTS: Continuous 24-hr electrocardiographic monitoring was performed, and serum (extracellular) and erythrocyte (intracellular) potassium concentrations ([K+]e and [K+]i) were determined, before cardiopulmonary bypass, immediately postoperatively, and at 2, 4, 12, and 20 hrs after elective coronary bypass grafting in 31 patients. INTERVENTIONS: None. Potassium replacement was left to the discretion of the attending physicians. MEASUREMENTS AND MAIN RESULTS: Although the mean [K+]e varied significantly during the postoperative 24-hr period (p<.0001), the [K+]i did not (p = .953). No significant correlations were found between premature ventricular beats and [K+]i, [K+]e, or [K+]i/[K+]e (all p>.05). However, among the few patients who had one or more episodes of ventricular tachycardia (VT) within 30 mins of a study K+ sample, the mean [K+]e was significantly lower during the episode(s) of VT compared with the mean [K+]e in the absence of VT (p<.01). CONCLUSIONS: Although it is clear that over the clinically acceptable range of [K+]e and [K+]i concentrations seen in this population, there is no correlation between potassium concentrations and the occurrence of premature ventricular beats, the infrequent association of more serious ventricular ectopy, VT, with lower [K+]e concentrations supports the practice of using serum potassium to guide potassium replacement in patients after cardiac operations.
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Potasio/sangre , Complejos Prematuros Ventriculares/sangre , Puente de Arteria Coronaria , Unidades de Cuidados Coronarios , Electrocardiografía Ambulatoria , Eritrocitos/metabolismo , Femenino , Hospitales Universitarios , Humanos , Hipopotasemia/sangre , Hipopotasemia/etiología , Hipopotasemia/fisiopatología , Hipopotasemia/prevención & control , Infusiones Intravenosas , Masculino , Persona de Mediana Edad , Cloruro de Potasio/administración & dosificación , Estudios Prospectivos , Complejos Prematuros Ventriculares/etiología , Complejos Prematuros Ventriculares/fisiopatología , Complejos Prematuros Ventriculares/prevención & controlRESUMEN
OBJECTIVE: The lung injury regularly associated with cardiopulmonary bypass (CPB) may be linked to gut mucosal dysfunction occurring as the result of mucosal ischemia associated with nonpulsatile CPB. To examine this possibility we postulated that the weak-beta 2 agonist dopexamine would improve gut mucosal blood flow, thereby decreasing gut and lung dysfunction seen after CPB in sheep. METHODS: Anesthetized sheep had 2 h of hypothermic (24 degrees C), nonpulsatile CPB, and 60 min of cold, blood cardioplegic arrest. After warming they were separated from CPB for 2 h of reperfusion. Before and during CPB, dopexamine at 2 micrograms/kg/min (n = 7) or saline (n = 7) were infused in a blinded fashion. Hemodynamic parameters were measured. Biatrial thromboxane B2 levels were obtained. Mesenteric arterial flow (QSMA), mucosal flow (Qmuc), FD-4 clearance (ClFD-4), and tonometric pHi were measured at baseline and 30-min intervals on, and after, CPB. RESULTS: After CPB, similar reductions in MAP were seen (P < 0.05 vs. baseline), but heart rate and the mean pulmonary vascular resistance were significantly increased in the dopexamine animals (P < 0.05 vs. placebo). Plasma thromboxane was similarly increased in both groups after CPB (P < 0.05 vs. baseline), returning to baseline 1 h after CPB. The Qsma was not altered, but a statistically significant decrease in Qmuc and pHi occurred in both groups (P < 0.05 vs. baseline). In both groups FD-4 clearance reached a peak 30 min after CPB (P < 0.05; dopexamine vs. baseline). After 2 h neither of these changes returned to control levels. CONCLUSIONS: In this ovine model, gut mucosal ischemia and increased permeability occur with hypothermic CPB, but dopexamine administration during CPB, compared to placebo, neither ameliorates these intestinal derangements nor reduces post-CPB lung pathophysiology.
Asunto(s)
Agonistas Adrenérgicos beta/farmacología , Puente Cardiopulmonar , Dopamina/análogos & derivados , Mucosa Intestinal/irrigación sanguínea , Pulmón/irrigación sanguínea , Daño por Reperfusión/fisiopatología , Animales , Permeabilidad Capilar , Puente Cardiopulmonar/efectos adversos , Dopamina/farmacología , Hemodinámica/fisiología , Concentración de Iones de Hidrógeno , Arterias Mesentéricas/efectos de los fármacos , Arterias Mesentéricas/fisiología , Oxígeno/metabolismo , Circulación Pulmonar/efectos de los fármacos , Circulación Pulmonar/fisiología , Daño por Reperfusión/sangre , Daño por Reperfusión/etiología , Ovinos , Tromboxano B2/sangreRESUMEN
OBJECTIVES: Minimally invasive direct coronary artery bypass permits arterial revascularization without cardiopulmonary bypass, potentially decreasing associated morbidity. The procedure is, however, technically challenging and associated with significant postoperative pain resulting from retraction through the small incision. METHODS AND PATIENT SELECTION: From December 1996 to April 1997, eight patients underwent grafting of the left anterior descending coronary artery by use of a short segment of right inferior epigastric artery attached proximally to the side of an in situ left internal thoracic artery. We have termed this procedure the "H" graft MIDCAB. RESULTS: No patients required intraoperative conversion to conventional bypass. No postoperative deaths or myocardial infarctions occurred. Six patients with normal renal function underwent postoperative angiography that demonstrated graft patency with rapid filling of the left anterior descending coronary in each case. Postoperatively clinical signs of acute ischemia were resolved or a normal exercise tolerance test was obtained in all patients. The median postoperative length of stay was 3 days. Rib spreading and chest wall retraction were not required in any procedure. CONCLUSIONS: The "H" graft procedure is an attractive alternative to standard minimally invasive bypass because of greater technical simplicity, the avoidance of internal thoracic artery harvest, and excellent visualization with no chest wall retraction.
Asunto(s)
Puente de Arteria Coronaria/métodos , Enfermedad Coronaria/cirugía , Arterias Epigástricas/trasplante , Femenino , Humanos , Masculino , Arterias Mamarias/trasplante , Persona de Mediana Edad , Procedimientos Quirúrgicos Mínimamente InvasivosRESUMEN
OBJECTIVE: To determine the difference in wound complication and infection rates between suture and staple closure techniques applied to clean incisions in coronary bypass patients. BACKGROUND: The true incidence of postoperative wound complications, and their correlation with closure techniques, has been obscured by study designs incorporating small numbers, retrospective short follow-up, uncontrolled host factors, and narrowly defined complications. METHODS: Sternal and leg wounds were studied prospectively, each patient serving as his or her own control. Two hundred forty-two patients with sternal and saphenous vein harvest wounds had half of each wound closed with staples and the other half with intradermal sutures (484 sternal and 516 leg segments). Wound complications were defined as drainage, erythema, separation, necrosis, seroma, or infection. Infections were identified in the subset having purulent drainage, antibiotic therapy, or debridement. Wounds were examined at discharge, at 1 week after discharge, and at 3 to 4 weeks after operation. Patient preferences for closure type were assessed 3 to 4 weeks after operation. RESULTS: Neither leg nor sternal wounds had a statistically significant difference in infection rate according to closure method (leg sutured = 9.3% vs. leg stapled = 8.9%; p = 0.99, and sternal sutured = 0.4% vs. sternal stapled = 2.5%; p = 0.128). There was, however, a greater complication rate in stapled segments (leg stapled = 46.9% vs. leg sutured = 32.6%; p = 0.001, and sternal stapled = 14.9% vs. sternal sutured = 3.7%; p = 0.00005). Sutures were favored over staples among patients who expressed a preference (sternal = 75.6%, leg = 74.6%). CONCLUSIONS: With the host factors controlled by pairing staples and sutures in each patient, we demonstrated a similar incidence of infection but a significantly lower incidence of total wound complications with intradermal suture closure than with staple closure.
Asunto(s)
Puente de Arteria Coronaria , Engrapadoras Quirúrgicas , Técnicas de Sutura , Anciano , Procedimientos Quirúrgicos Dermatologicos , Complicaciones de la Diabetes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Obesidad/complicaciones , Estudios ProspectivosRESUMEN
BACKGROUND: We previously have established characteristics predictive of the need for coronary artery bypass grafting (CABG) over many years after successful percutaneous transluminal coronary angioplasty (PTCA). In this study, we examined the factors associated with the need for CABG within 1 year of successful PTCA, and the recent impact of newer, catheter-based technologies. METHODS: From January 1982 through December 1995, 234 patients underwent CABG within 1 year of a successful "index" PTCA at our hospital. Emergency operations within 12 hours of index PTCA were excluded. These cases were matched with 234 controls who underwent a successful index PTCA but did not require a subsequent CABG during the next year. Cases were matched by the date of their index PTCA, and 1-year follow-up was complete for all patients. RESULTS: Before index PTCA there were no differences between the groups in terms of age, sex, diabetes, prior myocardial infarction, ejection fraction, duration of anginal symptoms, hypertension, hyperlipidemia, family history, or obesity (all nonsignificant). At index PTCA the cases had a greater mean number of lesions measuring 70% or greater compared with the controls (2.8 versus 1.8, respectively; p < 0.0001). The cases were more likely to have critical (70% or greater) proximal left anterior descending artery, proximal first obtuse marginal artery, and right posterior descending artery stenoses. The use of stents or atherectomy devices was not significantly more common among the controls (21% of controls versus 17.1% of cases; p = 0.35). Complete revascularization was achieved in significantly fewer of the cases than the controls (91 versus 156, respectively; p < 0.0001). The cases underwent CABG at a mean of 3 months (86% within 6 months) after PTCA. Among those who had a diagnostic catheterization, 52% of the patients had both restenosis of a dilated lesion and progression of other disease. Only 5 of 75 patients who had restenosis of a dilated lesion had a stent or an atherectomy device used at index PTCA. Of note, 13% (30 of 234) required an emergency operation, with an overall operative mortality rate of 3% (7 of 234). CONCLUSIONS: Although the likelihood of local restenosis is decreased by newer interventional techniques, the need for CABG within 1 year after successful PTCA is not diminished. The number of critical lesions and their location are the best predictors of the need for early CABG. If early post-PTCA CABG is to be avoided, patients who cannot be completely revascularized by PTCA should be revascularized by CABG.
Asunto(s)
Angioplastia Coronaria con Balón , Puente de Arteria Coronaria , Enfermedad Coronaria/terapia , Estudios de Casos y Controles , Constricción Patológica , Enfermedad Coronaria/cirugía , Progresión de la Enfermedad , Femenino , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
From January 1996 to May 1997, minimally invasive direct coronary artery bypass (MIDCAB) through a small anterior thoracotomy without cardiopulmonary bypass was completed in 31 of 32 patients (Male: Female=1.9:1, mean age=64.6 years, 11 (34.4%)>70 years). Twenty, five, and seven patients had one, two, and three vessel disease respectively. Twelve patients presented with unstable angina, seven had prior myocardial infarction, one had a pre-operative intra-aortic balloon pump, and four had prior coronary artery bypass grafting (CABG). Eight were diabetic, five had chronic obstructive pulmonary disease, and one was morbidly obese. Our newly developed coronary artery immobilizing and occluding device facilitated the coronary anastomosis. There were no post-procedure deaths, no peri-operative myocardial infarctions, and no strokes. One patient required intra-operative conversion to conventional CABG for an intramyocardial target vessel. Two patients had conversion after post-operative angiogram demonstrated incorrect target identification and early graft occlusion. Four patients had limited access graft revision (two kinks, one graft injury, and one haemorrhage). Thirty-one of the 32 patients were followed from 0.5 to 16 months and 30 reported no post-operative cardiac events (one required PTCA to another vessel). We conclude that MIDCAB is safe and effective.
Asunto(s)
Puente de Arteria Coronaria/estadística & datos numéricos , Enfermedad Coronaria/cirugía , Procedimientos Quirúrgicos Mínimamente Invasivos/estadística & datos numéricos , Adulto , Anciano , Anciano de 80 o más Años , Angiografía , Boston , Puente Cardiopulmonar/estadística & datos numéricos , Puente de Arteria Coronaria/efectos adversos , Puente de Arteria Coronaria/métodos , Femenino , Estudios de Seguimiento , Humanos , Tiempo de Internación , Masculino , Arterias Mamarias/diagnóstico por imagen , Arterias Mamarias/cirugía , Persona de Mediana Edad , Procedimientos Quirúrgicos Mínimamente Invasivos/efectos adversos , Procedimientos Quirúrgicos Mínimamente Invasivos/métodos , Revascularización Miocárdica , Reoperación , Instrumentos Quirúrgicos , ToracotomíaRESUMEN
Patients who undergo cardiopulmonary bypass frequently have neuropsychologic dysfunction. This study was undertaken to determine whether altered cerebral perfusion and vascular responses may in part lead to these neuropsychologic changes. Pigs were placed on normothermic cardiopulmonary bypass for 2 hours. Basal cerebral blood flow and in vivo responses to administration by internal carotid artery of neuronally released vasoactive substances were evaluated before and 5 to 15 minutes after termination of cardiopulmonary bypass. Another group of pigs were placed on cardiopulmonary bypass for 2 hours and then perfused off bypass for 1 additional hour. In vitro responses of cerebral arterial microvessels (100 to 175 microns) from both groups were examined in a pressurized (40 mm Hg) no-flow state with videomicroscopy. Vessels from uninstrumented pigs served as control preparations for in vitro studies. Cerebrovascular resistance and cerebral perfusion were maintained constant during cardiopulmonary bypass and after separation from bypass. The internal carotid artery infusion of acetylcholine (cholinergic agonist) caused increased internal carotid artery blood flow before cardiopulmonary bypass but decreased blood flow after cardiopulmonary bypass. After 2 hours of cardiopulmonary bypass, the increase in internal carotid artery blood flow induced by isoproterenol (a beta-adrenoceptor agonist) was reduced, whereas the response to sodium nitroprusside (a guanylate cyclase activator) was unchanged. In vitro acetylcholine-induced microvascular vasodilation was converted to a contractile response and isoproterenol elicited less relaxation after 2 hours of cardiopulmonary bypass. One hour of cerebral perfusion after cardiopulmonary bypass caused a further reduction in isoproterenol-induced relaxation but had no further effect on the cholinergically mediated response. In vitro relaxation responses to sodium nitroprusside and forskolin (an adenylate cyclase activator) were similar in all experimental groups, suggesting that second-messenger mechanisms remain intact after normothermic cardiopulmonary bypass. In conclusion, basal cerebrovascular resistance and internal carotid artery blood flow are maintained if the systemic circulation and pressure are supported with fluid administration after cardiopulmonary bypass. Agonist-induced vasodilation of cerebral microvessels to cholinergic and beta-adrenoceptor stimulation are selectively impaired after normothermic cardiopulmonary bypass, whereas second-messenger mechanisms remain intact.
Asunto(s)
Sistema Nervioso Autónomo/fisiopatología , Circulación Cerebrovascular , Circulación Extracorporea , Acetilcolina/administración & dosificación , Acetilcolina/farmacología , Agonistas Adrenérgicos beta/administración & dosificación , Agonistas Adrenérgicos beta/farmacología , Animales , Circulación Sanguínea , Presión Sanguínea , Puente Cardiopulmonar/métodos , Arteria Carótida Interna , Arterias Cerebrales/efectos de los fármacos , Circulación Cerebrovascular/efectos de los fármacos , Agonistas Colinérgicos/administración & dosificación , Agonistas Colinérgicos/farmacología , Colforsina/administración & dosificación , Colforsina/farmacología , Activación Enzimática , Circulación Extracorporea/métodos , Femenino , Guanilato Ciclasa/metabolismo , Inyecciones Intraarteriales , Isoproterenol/administración & dosificación , Isoproterenol/farmacología , Masculino , Microcirculación/efectos de los fármacos , Nitroprusiato/administración & dosificación , Nitroprusiato/farmacología , Sistemas de Mensajero Secundario/efectos de los fármacos , Porcinos , Resistencia Vascular/efectos de los fármacos , Vasodilatadores/administración & dosificación , Vasodilatadores/farmacologíaRESUMEN
BACKGROUND: Total cardiopulmonary bypass, in an ovine model, is associated with increased pulmonary thromboxane A2 production, cellular sequestration of white cells and platelets, transient pulmonary hypertention, and increased lung lymph flow and lymph protein clearance when compared with respective findings with partial cardiopulmonary bypass. This study evaluates the effect of neutrophil adhesion blockade on lung injury after cardiopulmonary bypass. METHODS: Two groups of anesthetized sheep were placed on total cardiopulmonary bypass without assisted ventilation. One group of seven sheep was treated before and during total cardiopulmonary bypass with the neutrophil adhesion blocker NPC 15669. A second group of seven sheep did not receive NPC 15669 treatment before total cardiopulmonary bypass. A third group of seven sheep was treated with NPC 15669 before initiation of partial cardiopulmonary bypass with continued assisted ventilation. Aortic occlusion and hypothermia were not used. After 90 minutes all sheep were separated from cardiopulmonary bypass, with resumption of assisted ventilation and pulmonary arterial flow. After 30 minutes the left atrial pressure was elevated mechanically. Hemodynamics, thromboxane A2 levels, platelet levels, and white blood cell and plasma protein concentrations were measured before cardiopulmonary bypass and afterwards at four 15-minute intervals. Samples were taken from the right and left atria simultaneously. Lung lymph protein levels and flow were measured before and after cardiopulmonary bypass at two 30-minute intervals. RESULTS: In the total cardiopulmonary bypass group not treated with NPC 15669 signs of lung injury developed after cardiopulmonary bypass. Animals treated with NPC 15669 did not manifest a similar degree of lung injury after either partial or total cardiopulmonary bypass. Increased pulmonary vascular resistance did not develop in treated sheep nor did sequestration of platelets or white blood cells occur. Despite the drug, increased pulmonary capillary permeability after total cardiopulmonary bypass persisted, but was reduced. CONCLUSIONS: Compared with unmodified total cardiopulmonary bypass, blockade of neutrophil adhesion with NPC 15669 reduces, but does not entirely eliminate, lung derangement after total cardiopulmonary bypass.
Asunto(s)
Antiinflamatorios no Esteroideos/farmacología , Puente Cardiopulmonar/efectos adversos , Leucina/análogos & derivados , Enfermedades Pulmonares/etiología , Neutrófilos/efectos de los fármacos , Neutrófilos/fisiología , Daño por Reperfusión/etiología , Animales , Antiinflamatorios no Esteroideos/uso terapéutico , Adhesión Celular/efectos de los fármacos , Leucina/farmacología , Leucina/uso terapéutico , Pulmón/efectos de los fármacos , Pulmón/fisiopatología , Enfermedades Pulmonares/prevención & control , Daño por Reperfusión/prevención & control , Ovinos , Tromboxano B2/sangre , Resistencia VascularRESUMEN
OBJECTIVE: To determine the ability of transesophageal echocardiography to accurately identify or exclude left atrial thrombi. DESIGN: Prospective cohort study. SETTING: University hospital. PATIENTS: 231 consecutive patients having transesophageal echocardiography before elective repair or replacement of the mitral valve or excision of a left atrial tumor. Fifty-six percent of patients had a history of atrial fibrillation, and 17% had a history of thromboembolism. MEASUREMENT: Identification of left atrial thrombi during transesophageal echocardiographic examination and comparison with direct near-simultaneous visualization during cardiac surgery. RESULTS: Transesophageal echocardiography identified 14 left atrial thrombi in 14 patients (6%). Thrombus size range from 3 to 80 mm. Surgery confirmed 12 of 14 thrombi (86%), including 9 thrombi confined to the left appendage. No additional thrombi were found on direct inspection of the atria (sensitivity, 100% [95% CI, 74% to 100%]; specificity, 99% [CI, 97% to 99.9%]; positive predictive value, 86% [12/14]; negative predictive value, 100% [217/217]; for a population that had a 5.2% prevalence of thrombi). All 12 surgically confirmed thrombi were identified by two independent observers. Neither thrombus seen by only a single observer on transesophageal echocardiography was confirmed during direct inspection of the atria at surgery. CONCLUSION: Transesophageal echocardiography is highly accurate for identifying left atrial thrombi and can be used clinically to exclude left atrial thrombi.
Asunto(s)
Ecocardiografía Transesofágica , Atrios Cardíacos/diagnóstico por imagen , Trombosis/diagnóstico por imagen , Adulto , Anciano , Femenino , Humanos , Periodo Intraoperatorio , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Sensibilidad y EspecificidadRESUMEN
We sought characteristics predictive of the need for operative revascularization subsequent to a successful coronary angioplasty. Through June 1993, 128 patients who had successful percutaneous transluminal coronary angioplasty (PTCA) between January 1982 and March 1989 required subsequent coronary artery bypass grafting (CABG) at our hospital. These cases were matched with 128 controls who had a successful PTCA but did not require subsequent CABG. Controls were matched to cases by the date of their initial PTCA. Before initial PTCA there were no differences between the cases and controls in terms of age, sex, prior myocardial infarction, ejection fraction, duration of anginal symptoms, hypertension, hyperlipidemia, family history, or obesity (all not significant). A greater number of cases had diabetes (35 versus 18; p = 0.009). Angiography before initial PTCA revealed that cases had a greater mean number of total lesions (4.1 versus 3.3; p = 0.002) and a higher incidence of left anterior descending and circumflex artery stenoses of 70% or greater (98 versus 75 and 57 versus 34, respectively; p = 0.006). The mean number of lesions successfully dilated was greater in cases (2.4 versus 1.7; p = 0.0001). Cases had CABG at a mean interval of 16.7 +/- 23 months. There were 17 late deaths among cases and 9 among the controls at a mean of 38.6 +/- 30 months. The survival probability at 5 years was 94.5% for controls and 87.9% for cases (p = 0.048). Initial revascularization by PTCA is followed by CABG at a brief interval in a subset of patients who have markers of more severe disease than do patients who do not require early CABG.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Angioplastia Coronaria con Balón , Puente de Arteria Coronaria , Enfermedad Coronaria/terapia , Angioplastia Coronaria con Balón/economía , Estudios de Casos y Controles , Puente de Arteria Coronaria/economía , Honorarios y Precios , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Recurrencia , Índice de Severidad de la Enfermedad , Análisis de Supervivencia , Insuficiencia del TratamientoRESUMEN
Previous studies have shown an increase in left atrial plasma thromboxane (TBX) level and associated increase in lung injury parameters after total cardiopulmonary bypass (t-CPB) but not after partial cardiopulmonary bypass (p-CPB). We used dazmegrel to study the effect of TBX synthesis inhibition on lung injury after t-CPB compared with p-CPB. Sheep were placed on t-CPB without ventilation and with pulmonary artery occlusion (n = 7) or p-CPB with ventilation and an unrestricted pulmonary artery (n = 7). All sheep were treated with dazmegrel. After 90 minutes we separated the sheep from CPB. Plasma TBX, platelets, white blood cells, protein concentration, lung lymph protein, flow, and pulmonary vascular resistance were measured before and after CPB. Lung biopsies were also obtained. Minimal derangement of these pulmonary parameters was seen after either p-CPB or t-CPB. Inhibition of TBX synthesis virtually eliminated the lung injury previously reported after t-CPB, when compared with p-CPB. Clearly TBX has an important role in mediating lung injury after t-CPB.
Asunto(s)
Arteriopatías Oclusivas/prevención & control , Puente Cardiopulmonar/efectos adversos , Imidazoles/uso terapéutico , Inhibidores de Agregación Plaquetaria/uso terapéutico , Arteria Pulmonar , Daño por Reperfusión/prevención & control , Animales , Arteriopatías Oclusivas/sangre , Arteriopatías Oclusivas/etiología , Arteriopatías Oclusivas/fisiopatología , Proteínas Sanguíneas/efectos de los fármacos , Proteínas Sanguíneas/metabolismo , Puente Cardiopulmonar/métodos , Atrios Cardíacos , Imidazoles/farmacología , Linfa/metabolismo , Linfa/fisiología , Inhibidores de Agregación Plaquetaria/farmacología , Recuento de Plaquetas , Cuidados Preoperatorios , Circulación Pulmonar , Daño por Reperfusión/sangre , Daño por Reperfusión/etiología , Daño por Reperfusión/fisiopatología , Ovinos , Tromboxanos/biosíntesis , Tromboxanos/sangre , Resistencia VascularRESUMEN
Total cardiopulmonary bypass with associated reduced pulmonary blood flow causes significant alterations of endothelium-dependent pulmonary microvascular responses after resumption of normal perfusion. To determine if this change in pulmonary vascular reactivity may influence the responses of pulmonary arterioles to protamine and histamine, we examined isolated pulmonary microvessels after cardiopulmonary bypass. Sheep were heparinized, cannulated, and placed on either total bypass without ventilation or partial bypass (70% of baseline pulmonary arterial flow) with continued ventilation. After 90 minutes, sheep were separated from cardiopulmonary bypass and the lungs were perfused normally for 60 minutes. Vessels from noninstrumented sheep were used as controls. Peripheral pulmonary arterioles (90 to 190 microns) were cannulated, pressurized (20 mm Hg) in a no-flow state, and examined with video microscopy. After precontraction of vessels with the thromboxane A2 analog U46619 by 18% to 25% of the baseline diameter, vasoactive agents were applied. Protamine sulfate, histamine, heparin, and the protamine-heparin complex caused significant dose-dependent relaxations of control pulmonary microvessels. These relaxation responses were substantially reduced or converted to contractile responses in endothelium-denuded vessels, which suggests that these relaxations are mediated through endothelium-dependent mechanisms. After partial bypass, responses to protamine and histamine were slightly reduced compared with the respective responses of control vessels, whereas the relaxation to protamine-heparin complex was not significantly altered. After total bypass, relaxation responses to protamine and protamine-heparin complex were markedly reduced, whereas histamine induced contraction of pulmonary microvessels. Endothelium-independent relaxation to sodium nitroprusside was not affected by partial cardiopulmonary bypass and was slightly reduced after total bypass. A reduced direct vascular relaxation response to protamine and increased contractile response to histamine (or other humoral substances released during the systemic administration of protamine sulfate) may contribute to the elevation of pulmonary vascular resistance during infusion of protamine after cardiopulmonary bypass.
Asunto(s)
Puente Cardiopulmonar , Histamina/farmacología , Pulmón/irrigación sanguínea , Protaminas/farmacología , Animales , Arginina/análogos & derivados , Arginina/farmacología , Femenino , Heparina/farmacología , Técnicas In Vitro , Indometacina/farmacología , Pulmón/efectos de los fármacos , Microcirculación/efectos de los fármacos , Óxido Nítrico/antagonistas & inhibidores , Nitroprusiato/farmacología , Ovinos , Resistencia Vascular/efectos de los fármacos , omega-N-MetilargininaRESUMEN
The purpose of the present study was to examine whether adrenoceptor-mediated responses of porcine coronary resistance arteries are affected by cardioplegic arrest under conditions of extracorporeal circulation (cardiopulmonary bypass; CPB). Pigs were placed on CPB. The hearts were arrested with a cold hyperkalemic crystalloid cardioplegic solution for 1 h, then were reperfused for 1 h. In vivo and in vitro beta-adrenoceptor-mediated responses were compared before CPB and 2 min and 1 h after initiation of reperfusion. In vitro responses were studied in a pressurized no-flow state with video microscopy. Isoproterenol (0.02 micrograms.kg-1.min-1, intracoronary) increased coronary blood flow by 100 +/- 32% (P < 0.001) before CPB and cardioplegic arrest, 17 +/- 7% 2 min postcardioplegia (P < 0.01), and 71 +/- 9 (P < 0.001) after 1 h of reperfusion. Relaxation of precontracted microvessels (90-180 micron) to isoproterenol, NaF, forskolin, and adenosine was reduced after cardioplegic arrest (all P < 0.001). After 1 h of postcardiolegia-reperfusion, relaxation responses to forskolin and adenosine were completely restored, whereas the responses to isoproterenol (P < 0.05) and NaF (P < 0.10) were only partially recovered. Cardioplegic arrest and postcardioplegia-reperfusion blunted the alpha 2-adrenoceptor-mediated endothelium-dependent relaxation to clonidine (P < 0.001) but did not affect the minimal (< 4%) contractile response to the alpha 1-adrenoceptor agonist phenylephrine or the relaxation to nitroprusside. These results show that hyperkalemic cardioplegia results in the generalized defect in the beta-adrenoceptor-GS protein-adenylate cyclase pathway, which is significantly restored after reperfusion.
Asunto(s)
Circulación Coronaria/fisiología , Circulación Extracorporea , Paro Cardíaco Inducido , Microcirculación/fisiología , Receptores Adrenérgicos/fisiología , Adenosina/farmacología , Animales , Soluciones Cardiopléjicas , Puente Cardiopulmonar , Colforsina/farmacología , Cristalización , Femenino , Isoproterenol/farmacología , Masculino , Nitroprusiato/farmacología , Receptores Adrenérgicos alfa/efectos de los fármacos , Receptores Adrenérgicos alfa/fisiología , Receptores Adrenérgicos beta/efectos de los fármacos , Receptores Adrenérgicos beta/fisiología , Fluoruro de Sodio/farmacología , Porcinos , Vasodilatación/efectos de los fármacosRESUMEN
BACKGROUND: We have established that thromboxane B2 (TX) blood levels increase across the pulmonary circulation after total cardiopulmonary bypass (CPB) but not after partial CPB. In the present study, we used the same model and examined the parameters of pulmonary injury after total or partial CPB. METHODS AND RESULTS: Fourteen anesthetized sheep were placed on total CPB (n = 7), without ventilation and with occlusion of the pulmonary artery, or partial CPB (n = 7), with ventilation and an open pulmonary artery. After 90 minutes, the sheep were separated from CPB, and the pulmonary artery was perfused normally. After 30 minutes, we elevated left atrial pressure in all sheep. Plasma TX, plasma leukotriene B4, platelet counts, white blood cell counts, and plasma protein concentration were measured before CPB and every 15 minutes after CPB for 1 hour. The right and left atrial blood samples were obtained simultaneously. Pulmonary arterial pressure, left atrial pressure, and pulmonary arterial flow were measured. Pulmonary vascular resistance (PVR) was calculated for 30 minutes after CPB. Lung lymph protein, TX, leukotriene B4, and flow were measured before CPB and every 30 minutes after CPB for 1 hour. Pulmonary biopsies and bronchoalveolar lavage fluid were obtained before CPB and at the end of the experiment. After total CPB, levels of TX across the pulmonary circulation increased significantly, but leukotriene B4 remained constant. Platelets and white blood cells were consumed across the pulmonary circuit after total CPB but not after partial CPB. PVR increased by 170%, lymph flow increased by 233%, lung water content increased by 15%, and the ratio of lymph to plasma protein decreased by 20% after total CPB, but similar changes did not occur after partial CPB. CONCLUSIONS: During total CPB, the lungs are totally dependent on oxygen supply provided by nonpulsatile bronchial arterial flow. Lung injury seen with restoration of pulmonary artery flow and ventilation may be the result of an inflammatory response associated with TX elevation after a period of relative pulmonary ischemia. Pulmonary injury was not seen after less severe pulmonary arterial flow deprivation, with maintenance of ventilation (partial CPB). Although the specific cause is undetermined from these data, the occurrence of elevated TX levels and lung damage after total CPB is clearly established.
Asunto(s)
Puente Cardiopulmonar/efectos adversos , Pulmón/irrigación sanguínea , Circulación Pulmonar/fisiología , Daño por Reperfusión/etiología , Tromboxano B2/sangre , Animales , Puente Cardiopulmonar/métodos , Recuento de Leucocitos , Leucotrieno B4/sangre , Linfa/química , Recuento de Plaquetas , Daño por Reperfusión/sangre , Ovinos , Factores de TiempoRESUMEN
BACKGROUND: Cardiopulmonary bypass and crystalloid cardioplegia may lead to endothelial dysfunction in the coronary microcirculation. The aim of the present study was to examine whether the alteration of endothelium-dependent microvascular responses may be related to the generation of oxygen-derived free radicals. METHODS AND RESULTS: Pigs (30 kg) were heparinized and placed on cardiopulmonary bypass. The hearts were arrested for 1 hour with either plain hypothermic, hyperkalemic (25 mEq/L) crystalloid cardioplegic solution (n = 10) or crystalloid cardioplegic solution containing either deferoxamine (n = 8) or manganese superoxide dismutase (n = 6). Hearts were then reperfused for 1 hour while the pigs were separated from cardiopulmonary bypass. Noninstrumented pigs were used as controls (n = 8). Coronary microarteries (120 to 190 microns in diameter) were studied in vitro in a pressurized (40 mm Hg), no-flow state with videomicroscopy and electronic dimension analysis. After precontraction of microvessels, the endothelium-dependent and -independent agents were applied extraluminally. Serotonin caused a slight dilation of control vessels (percent dilation of acetylcholine-induced preconstriction at 10 mumol/L drug concentration, 5 +/- 8%; P < .05 versus crystalloid cardioplegia group) and a significant contractile response after crystalloid cardioplegia (-28 +/- 10%). Bradykinin elicited near complete relaxation of control vessels (96 +/- 3%, P < .05), whereas it caused considerably less relaxation after cardioplegia (33 +/- 9%). The addition of either deferoxamine or superoxide dismutase to the cardioplegic solution significantly (but not completely) preserved vasomotor responses of coronary microvessels to serotonin (9 +/- 6% and 11 +/- 4%, respectively; P < .05) or bradykinin (72 +/- 4% and 87 +/- 3%, respectively; P < .05). Endothelium-independent relaxations of vessels in response to sodium nitroprusside were similar in all groups. CONCLUSIONS: Either the hydroxyl radical synthesis inhibitor deferoxamine or manganese superoxide dismutase preserves endothelium-dependent relaxation during crystalloid cardioplegia-reperfusion. Therefore, ischemic cardioplegia-reperfusion-induced endothelial dysfunction is at least partially mediated by the generation of oxygen-derived free radicals.
Asunto(s)
Puente Cardiopulmonar , Vasos Coronarios/fisiopatología , Endotelio Vascular/fisiopatología , Paro Cardíaco Inducido , Daño por Reperfusión Miocárdica/etiología , Especies Reactivas de Oxígeno/metabolismo , Animales , Vasos Coronarios/efectos de los fármacos , Deferoxamina/farmacología , Endotelio Vascular/efectos de los fármacos , Depuradores de Radicales Libres , Radicales Libres , Daño por Reperfusión Miocárdica/metabolismo , Nitroprusiato/farmacología , Serotonina/farmacología , PorcinosRESUMEN
OBJECTIVE: The aim was to examine the mechanisms of coronary microvascular dysfunction during cardiopulmonary bypass and ischaemic arrest using a crystalloid cardioplegic solution. METHODS: Porcine hearts were arrested with cold hyperkalaemic (K+ = 25 mmol.litre-1) cardioplegic solution for 1 h during cardiopulmonary bypass and then reperfused for 1 h. Selected hearts were arrested but not reperfused. Coronary vessels of non-instrumented pigs were used as controls. In vitro vascular responses of subepicardial and subendocardial arterioles were examined in a pressurised (40 mm Hg) no flow state with video microscopy. RESULTS: Following 1 h of ischaemic cardioplegia, endothelium dependent relaxations of epicardial arterioles to the receptor mediated agent ADP and the non-receptor-mediated agent calcium ionophore A23187 were moderately reduced, and the contractile responses to KCl or the thromboxane A2 analogue U46619 were reduced compared to responses of vessels from control animals. After 1 h of reperfusion, U46619 caused contraction greater than control values, while contraction to KCl and endothelium dependent relaxations to ADP or A23187 were further reduced. Responses of endocardial microvessels to serotonin were slightly more affected by cardioplegia and reperfusion than were epicardial vessels, while the effect on responses of epicardial and endocardial vessels to bradykinin or A23187 were similar. Endothelium independent relaxation to sodium nitroprusside was not altered in any of the experimental groups. The addition of manganese superoxide dismutase to the cardioplegic solution markedly preserved endothelium dependent responses to ADP and A23187 and contractile response to U46619, compared to the responses of vessels from the plain crystalloid cardioplegia group, but had no effect on relaxation to sodium nitroprusside or on contraction to KCl. Five hours of normokalaemic hypothermia (5-10 degrees C) in Krebs buffer had minimal effect on vasodilator responses. Electron microscopy revealed preserved endothelial and smooth muscle cell structure, and focal mononuclear leucocyte-endothelium adherence following cardioplegic arrest and reperfusion. CONCLUSIONS: Ischaemic cardioplegia-reperfusion induced endothelium dependent and direct smooth muscle microvascular dysfunction is at least partially mediated by prolonged exposure of vessels to hyperkalaemia and to the generation of oxygen derived free radicals. Leucocytes probably mediate injury during reperfusion, while hypothermia has minimal effect on recovery of vasomotor function.
Asunto(s)
Soluciones Cardiopléjicas/efectos adversos , Vasos Coronarios/fisiopatología , Paro Cardíaco Inducido/efectos adversos , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico , Adenosina Difosfato/farmacología , Animales , Calcimicina/farmacología , Puente Cardiopulmonar , Vasos Coronarios/efectos de los fármacos , Vasos Coronarios/ultraestructura , Endocardio/efectos de los fármacos , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/fisiopatología , Femenino , Masculino , Microcirculación/ultraestructura , Microscopía Electrónica , Músculo Liso Vascular/efectos de los fármacos , Reperfusión Miocárdica , Pericardio/efectos de los fármacos , Cloruro de Potasio/farmacología , Endoperóxidos de Prostaglandinas Sintéticos/farmacología , Porcinos , Tromboxano A2/análogos & derivados , Tromboxano A2/farmacología , Vasodilatación/efectos de los fármacosRESUMEN
OBJECTIVES: This study was designed to evaluate more closely the true in-hospital costs of elective revascularization by directional coronary atherectomy and intracoronary stenting and to compare these costs with those of the traditional revascularization alternatives (i.e., conventional balloon angioplasty and coronary artery bypass surgery). BACKGROUND: Previous studies have suggested that total hospital charges for directional coronary atherectomy or intracoronary stenting are significantly higher than those for conventional angioplasty. However, hospital charges do not necessarily reflect true economic costs, and their use may provide misleading data with regard to cost-effectiveness. METHODS: We analyzed in-hospital charges from the itemized hospital accounts of 300 patients undergoing elective angioplasty, directional atherectomy, Palmaz-Schatz coronary stenting or bypass surgery between January 1, 1990 and December 31, 1991. Costs were then derived by adjusting itemized patient accounts for department-specific cost/charge ratios. Catheterization laboratory costs were based on actual resource consumption, and daily room costs were adjusted for the intensity of nursing services provided. RESULTS: Length of hospital stay was similar for atherectomy (2.3 +/- 1.5 days) and conventional angioplasty (2.6 +/- 1.7 days) but significantly longer for stenting (5.5 +/- 2.6 days, p < 0.05). Total costs were also significantly higher for coronary stenting ($7,878 +/- $3,270, median $6,699, p < 0.05) than for angioplasty ($5,396 +/- $2,829, median $4,753) or atherectomy ($5,726 +/- $2,716, median $4,986). However, length of stay, resource consumption (laboratory and radiologic testing, drugs, blood products, for example) and total costs for bypass surgery were still greater than for any of the percutaneous interventional procedures. CONCLUSIONS: In contrast to previous studies utilizing only hospital charges, the in-hospital costs of angioplasty and directional coronary atherectomy were similar. Although the cost of coronary stenting was approximately $2,500 higher than that of conventional angioplasty, the magnitude of this difference was smaller than the $6,300 increment previously suggested on the basis of analysis of hospital charges. These findings reflect the inherent discrepancies between cost-based and charge-based methodologies and may have important implications for future studies evaluating the relative cost-effectiveness of newer coronary interventions.
Asunto(s)
Angioplastia Coronaria con Balón/economía , Aterectomía Coronaria/economía , Puente de Arteria Coronaria/economía , Enfermedad Coronaria/terapia , Procedimientos Quirúrgicos Electivos/economía , Anciano , Cateterismo Cardíaco/economía , Cateterismo Cardíaco/estadística & datos numéricos , Enfermedad Coronaria/economía , Análisis Costo-Beneficio , Honorarios y Precios , Femenino , Costos de la Atención en Salud , Investigación sobre Servicios de Salud , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Stents/economía , Resultado del TratamientoRESUMEN
Pulmonary vascular resistance is frequently elevated after cardiac operations in which cardiopulmonary bypass is used. In our study of the possible contribution of altered pulmonary microvascular reactivity to this condition, sheep were heparinized, cannulated via the aorta and right atrium, and placed on total cardiopulmonary bypass. After 90 minutes of total cardiopulmonary bypass and pulmonary arterial occlusion, the sheep were removed from cardiopulmonary bypass, and their lungs were perfused normally for 60 minutes. Noninstrumented animals were used as controls. To evaluate the effect of 90 minutes of extracorporeal circulation without reduced pulmonary perfusion, we studied additional sheep after they underwent right heart bypass with a pump-oxygenator. Pulmonary microarterial vessels (130 to 230 microns in diameter) from each group were examined in vitro in a pressurized (20 mm Hg), no-flow state with video microscopic imaging and electronic dimension analysis. After preconstriction of vessels with the thromboxane A2 analog U46619 by 30% to 40% of the baseline diameter, vasoactive drugs were applied extraluminally. Serotonin caused control microvessels to dilate. In the presence of the nitric oxide synthetase inhibitor NG-methyl-L-arginine, this was converted to a significant contractile response. Acetylcholine alone had minimal effect on control vessels. However, in the presence of the cyclooxygenase inhibitor indomethacin, acetylcholine caused a significant relaxation response. After total cardiopulmonary bypass and pulmonary reperfusion, pulmonary microvessels contracted significantly when exposed to acetylcholine and serotonin, compared with respective control responses. Both these contractile responses were inhibited in the presence of indomethacin. Endothelium-independent responses to sodium nitroprusside and U46619 and dilation responses to adenosine were not altered after cardiopulmonary bypass. Extracorporeal circulation with continued pulmonary arterial perfusion (right heart bypass group) had no effect on microvascular responses. In conclusion, total cardiopulmonary bypass with associated reduced pulmonary perfusion causes significant alterations of endothelium-dependent pulmonary microvascular responses because of the increased release of a constrictor prostanoid substance and possibly because of reduced release of endothelium-derived relaxing factor.
Asunto(s)
Puente Cardiopulmonar , Circulación Pulmonar , Acetilcolina/farmacología , Adenosina/farmacología , Animales , Femenino , Técnicas In Vitro , Microcirculación/patología , Microcirculación/fisiopatología , Nitroprusiato/farmacología , Endoperóxidos de Prostaglandinas Sintéticos/farmacología , Serotonina/farmacología , Ovinos , Tromboxano A2/farmacología , Resistencia Vascular , Vasoconstricción/efectos de los fármacos , Vasodilatación/efectos de los fármacosRESUMEN
Life-threatening ventricular ectopy can occur after cardiac operations. The actual incidence of ventricular ectopy and the ability to prevent it by the routine prophylactic use of lidocaine hydrochloride have not been established. We performed a double-blind, randomized, prospective trial involving 109 patients undergoing elective coronary artery revascularization. Patients received either lidocaine (n = 54) or a placebo (n = 55) after separation from bypass. A Holter monitor was affixed to each patient for subsequent review, and bedside intensive-care monitors with alarms were used for "real-time" surveillance. The code was broken when potentially malignant ventricular ectopy or side effects attributable to the study drug were noted. Three lidocaine patients and 2 placebo patients were dropped from the study because of hemodynamic instability or bleeding. Of the remaining 104 patients, the code was broken in 12 (24%) of the 51 in the lidocaine group (9 for ectopy and 3 for mental status changes) and 10 (19%) of the 53 in the placebo group (all for ectopy) (p = not significant). Twenty-four-hour Holter monitor evaluation demonstrated occasional ventricular ectopy in all patients and nonsustained ventricular tachycardia in 28% in the lidocaine group and 48% in the placebo group (p = not significant). The mean number of runs of ventricular tachycardia per patient was 0.53 in the lidocaine group and 1.6 in the placebo group (p = 0.035). There were no significant differences in terms of other ventricular ectopy, morbidity, or mortality. No ventricular fibrillation occurred in either group.(ABSTRACT TRUNCATED AT 250 WORDS)