RESUMEN
BACKGROUND: Transcatheter stent implantation has been employed to treat re-coarctation of the aorta in adolescents and young adults. The aim of this work is to use computational fluid dynamics to characterise haemodynamics associated with re-coarctation involving an aneurysmal ductal ampulla and aortic isthmus narrowing, which created minimal pressure drop, and to incorporate computational fluid dynamics's findings into decision-making concerning catheter-directed treatment. METHODS: Computational fluid dynamics permits numerically solving the Navier-Stokes equations governing pulsatile flow in the aorta, based on patient-specific data. We determined flow-velocity fields, wall shear stresses, oscillatory shear indices, and particle stream traces, which cannot be ascertained from catheterisation data or magnetic resonance imaging. RESULTS: Computational fluid dynamics showed that, as flow entered the isthmus, it separated from the aortic wall, and created vortices leading to re-circulating low-velocity flow that induced low and multidirectional wall shear stress, which could sustain platelet-mediated thrombus formation in the ampulla. In contrast, as flow exited the isthmus, it created a jet leading to high-velocity flow that induced high and unidirectional wall shear stress, which could eventually undermine the wall of the descending aorta. SUMMARY: We used computational fluid dynamics to study re-coarctation involving an aneurysmal ductal ampulla and aortic isthmus narrowing. Despite minimal pressure drop, computational fluid dynamics identified flow patterns that would place the patient at risk for: thromboembolic events, rupture of the ampulla, and impaired descending aortic wall integrity. Thus, catheter-directed stenting was undertaken and proved successful. Computational fluid dynamics yielded important information, not only about the case presented, but about the complementary role it can serve in the management of patients with complex aortic arch obstruction.
Asunto(s)
Aneurisma de la Aorta Torácica/cirugía , Coartación Aórtica/cirugía , Velocidad del Flujo Sanguíneo/fisiología , Cateterismo Cardíaco/métodos , Simulación por Computador , Procedimientos Endovasculares/métodos , Stents , Aorta Torácica/diagnóstico por imagen , Aorta Torácica/fisiopatología , Aneurisma de la Aorta Torácica/diagnóstico , Aneurisma de la Aorta Torácica/fisiopatología , Coartación Aórtica/diagnóstico , Coartación Aórtica/fisiopatología , Femenino , Humanos , Angiografía por Resonancia Magnética , Recurrencia , Adulto JovenRESUMEN
An adult case of polyvalvular heart disease syndrome diagnosed in an adult is presented. The characteristic facies and echocardiographic features of this rare autosomal dominant connective tissue disorder are presented.
Asunto(s)
Anomalías Múltiples , Enfermedades del Tejido Conjuntivo/diagnóstico , Cardiopatías Congénitas/diagnóstico , Enfermedades de las Válvulas Cardíacas/diagnóstico , Válvulas Cardíacas/anomalías , Ecocardiografía , Válvulas Cardíacas/diagnóstico por imagen , Humanos , Masculino , Persona de Mediana Edad , SíndromeRESUMEN
A healthy 20-year-old male presented with aborted sudden death. Both thoracic echocardiography and cardiac computed tomographic angiography demonstrated the characteristic findings of ALCAPA noting a dilated and tortuous right coronary artery, dilated coronary collateral arteries within the interventricular septum or along the surface of the heart, and visualization of the left coronary artery origin from the posterior aspect of the main pulmonary artery. Both imaging modalities demonstrated all three characteristic findings of this rare coronary anomaly and served as complementary imaging studies for surgical correction.
Asunto(s)
Síndrome de Bland White Garland/diagnóstico , Angiografía por Tomografía Computarizada/métodos , Angiografía Coronaria/métodos , Vasos Coronarios/diagnóstico por imagen , Ecocardiografía Doppler en Color/métodos , Arteria Pulmonar/diagnóstico por imagen , Tabique Interventricular/diagnóstico por imagen , Electrocardiografía , Humanos , Imagenología Tridimensional , Masculino , Arteria Pulmonar/anomalías , Adulto JovenRESUMEN
OBJECTIVES: Central (aorta) and Sano (right ventricle)-to-pulmonary artery (PA) shunts, palliative operations for infants with complex heart defects, can develop life-threatening thrombosis. We employed computational fluid dynamics (CFD) to study pulsatile flow in these shunts, with the goal to identify haemodynamic characteristics conducive to thrombus formation. METHODS: CFD, using the finite volume method with cardiac catheterization data, and computer simulations, based on angiography, were employed to determine flow-velocity field, wall shear stress (WSS) profile and oscillatory shear index (OSI). RESULTS: At prominent angulation, in central shunts (4 and 3.5 mm), WSS reached 245 and 123 (Pascal-Pa), peak systole and 137 and 46 Pa, end diastole; and, in Sano shunts (5 and 6 mm), WSS attained 203 and 133 Pa, peak systole and 1.6 and 1.5 Pa, end diastole. Counter-rotating flow vortices augmented WSS. These high WSSs can promote platelet aggregation, leading to thrombus formation. The OSIs averaged 0.39, indicative of multidirectional shearing forces. Shunt burden was assessed by averaging WSS, over its luminal area and the cardiac cycle. For the central shunts, these WSSs were 73.0 and 67.2 Pa; whereas, for the Sano shunts, 34.9 and 19.6 Pa. For modified Blalock-Taussig shunts (4 and 3.5 mm), the averaged WSSs were significantly lower at 26.0 and 27.5 Pa, respectively. CONCLUSIONS: CFD modelling is an important tool to determine blood flow behaviour in shunts. Graft angulation presents a risk for shear stress-induced, platelet- mediated thrombosis, which is more likely to occur in elongated central than in Sano shunts.
Asunto(s)
Procedimientos Quirúrgicos Cardíacos/efectos adversos , Simulación por Computador , Oclusión de Injerto Vascular/fisiopatología , Modelos Cardiovasculares , Arteria Pulmonar/fisiopatología , Flujo Pulsátil/fisiología , Trombosis/fisiopatología , Aorta Torácica/cirugía , Plaquetas , Oclusión de Injerto Vascular/etiología , Ventrículos Cardíacos/cirugía , Humanos , Hidrodinámica , Diseño de Prótesis , Arteria Pulmonar/cirugía , Estrés Mecánico , Trombosis/diagnóstico , Trombosis/etiologíaRESUMEN
Lithium is a potent psychotherapeutic agent that has gained wide acceptance in paediatrics, especially as adjunct treatment for severe behavioural, anxiety, and attention-deficit hyperactivity disorders, along with bipolar conditions. Its cardiac toxicity has been well-documented in adults; however, information is limited regarding lithium's effects on the heart in children. Therefore, paediatric cardiologists following-up children on lithium therapy should be cognizant of the cardiac side-effects and pathophysiology associated with this drug. In this manuscript, we used an illustrative case of a child who presented with lithium poisoning, in order to highlight adverse clinical manifestations that can arise from this medication. The cardiac cell membrane is thought to be the primary site of lithium's action. Thus, we reviewed lithium's effects on membrane electrogenic pumps and channels involved in the distribution and passage of sodium, potassium, and calcium across the sarcolemma, as these ions, and their associated currents, are the primary determinates of the action potentials underlying auto-rhythmicity and contractile activity of the heart.
Asunto(s)
Cardiomiopatías/inducido químicamente , Electrocardiografía/efectos de los fármacos , Carbonato de Litio/envenenamiento , Antidepresivos/envenenamiento , Antidepresivos/uso terapéutico , Trastorno Bipolar/tratamiento farmacológico , Cardiomiopatías/diagnóstico , Cardiomiopatías/fisiopatología , Preescolar , Humanos , Carbonato de Litio/uso terapéutico , Masculino , Factores de RiesgoRESUMEN
The central aortic shunt, consisting of a Gore-Tex (polytetrafluoroethylene) tube (graft) connecting the ascending aorta to the pulmonary artery, is a palliative operation for neonates with cyanotic congenital heart disease. These tubes often have an extended length, and therefore must be angulated to complete the connection to the posterior pulmonary arteries. Thrombosis of the graft is not uncommon and can be life-threatening. We have shown that a viscous fluid (such as blood) traversing a curve or bend in a small-caliber vessel or conduit can give rise to marked increases in wall shear stress, which is the major mechanical factor responsible for vascular thrombosis. Thus, the objective of this study was to use computational fluid dynamics to investigate whether wall shear stress (and shear rate) generated in angulated central aorta-to-pulmonary artery connections, in vivo, can be of magnitude and distribution to initiate platelet activation/aggregation, ultimately leading to thrombus formation. Anatomical features required to construct the computer-simulated blood flow pathways were verified from angiograms of central aortic shunts in patients. For the modeled central aortic shunts, we found wall shear stresses of (80-200 N/m(2)), with shear rates of (16,000-40,000/s), at sites of even modest curvature, to be high enough to cause platelet-mediated shunt thrombosis. The corresponding energy losses for the fluid transitions through the aorta-to-pulmonary connections constituted (70 %) of the incoming flow's mechanical energy. The associated velocity fields within these shunts exhibited vortices, eddies, and flow stagnation/recirculation, which are thrombogenic in nature and conducive to energy dissipation. Angulation-induced, shear stress-mediated shunt thrombosis is insensitive to aspirin therapy alone. Thus, for patients with central aortic shunts of longer length and with angulation, aspirin alone will provide insufficient protection against clotting. These patients are at risk for shunt thrombosis and significant morbidity and mortality, unless their anticoagulation regimen includes additional antiplatelet medications.
Asunto(s)
Aorta/cirugía , Prótesis Vascular/efectos adversos , Simulación por Computador , Hemodinámica , Arteria Pulmonar/cirugía , Trombosis/fisiopatología , Anastomosis Quirúrgica/métodos , Velocidad del Flujo Sanguíneo , Cianosis/fisiopatología , Cianosis/cirugía , Femenino , Cardiopatías Congénitas/fisiopatología , Cardiopatías Congénitas/cirugía , Humanos , Lactante , Masculino , Complicaciones Posoperatorias/etiología , Factores de Riesgo , Trombosis/etiologíaAsunto(s)
Anemia de Células Falciformes/diagnóstico , Ecocardiografía Transesofágica/métodos , Fibroma/diagnóstico por imagen , Neoplasias Cardíacas/diagnóstico por imagen , Adolescente , Anemia de Células Falciformes/complicaciones , Biopsia con Aguja , Procedimientos Quirúrgicos Cardíacos/métodos , Progresión de la Enfermedad , Femenino , Fibroma/complicaciones , Fibroma/patología , Fibroma/cirugía , Estudios de Seguimiento , Neoplasias Cardíacas/complicaciones , Neoplasias Cardíacas/patología , Neoplasias Cardíacas/cirugía , Humanos , Inmunohistoquímica , Resultado del TratamientoRESUMEN
Surgical treatment of functional single-ventricle heart disease with a modified Fontan procedure results in elevated central venous pressure. The case report describes a 19-year-old boy with hypoplastic left heart syndrome and Fontan palliation that resulted in frequent debilitating headaches after transcatheter closure of systemic venous-to-pulmonary venous collaterals. Measured increased intracranial pressure and prompt relief of the headaches with lumbar puncture favored a diagnosis of pseudotumor cerebri. After implantation of a lumboperitoneal shunt, the patient's headaches improved dramatically. Headaches are frequent in patients with Fontan circulation. The current literature supports a pivotal role of elevated dural venous sinus pressure in the pathogenesis of pseudotumor cerebri. The high superior and inferior vena caval pressures characteristic of modified Fontan anatomy may account for headaches in some of these patients.
Asunto(s)
Procedimiento de Fontan/efectos adversos , Síndrome del Corazón Izquierdo Hipoplásico/cirugía , Seudotumor Cerebral/etiología , Cateterismo Cardíaco , Humanos , Masculino , Complicaciones Posoperatorias , Seudotumor Cerebral/diagnóstico , Adulto JovenRESUMEN
Pulmonary arteriovenous fistulae are known to develop in patients who have functional single-ventricle heart disease and interruption of the inferior vena cava with direct hepatic drainage to the heart, in which a bidirectional Glenn shunt is the only source of pulmonary blood flow. The progressive systemic arterial hypoxemia that is associated with pulmonary arteriovenous fistulae can have important clinical consequences. Baffling the hepatic venous return to the pulmonary circulation can alleviate pulmonary arteriovenous fistulae.Herein, we present the case of a 13-year-old patient with modified Fontan anatomy and pulmonary arteriovenous fistulae, in whom redirection of a previously placed hepatic venous-to-right pulmonary artery conduit was required in order to increase systemic arterial oxygen saturation. Revision of the conduit improved mixing of hepatic venous effluent with blood flow from the bidirectional Glenn shunt. Three years after this revision, the patient's oxygen saturation remained stable at 90%, and his physical activity was markedly improved. We present our rationale for selected redirection of the conduit and discuss other surgical options that can improve hypoxemia that is associated with pulmonary arteriovenous fistulae.
Asunto(s)
Fístula Arteriovenosa/cirugía , Implantación de Prótesis Vascular , Procedimiento de Fontan/efectos adversos , Venas Hepáticas/cirugía , Hipoxia/cirugía , Arteria Pulmonar/cirugía , Venas Pulmonares/cirugía , Adolescente , Fístula Arteriovenosa/sangre , Fístula Arteriovenosa/etiología , Fístula Arteriovenosa/fisiopatología , Puente Cardiopulmonar , Hemodinámica , Venas Hepáticas/fisiopatología , Humanos , Hipoxia/sangre , Hipoxia/etiología , Hipoxia/fisiopatología , Masculino , Oxígeno/sangre , Flebografía , Arteria Pulmonar/fisiopatología , Venas Pulmonares/fisiopatología , ReoperaciónRESUMEN
A bidirectional Glenn shunt (BGS) was successfully incorporated into a two-ventricle repair for 10 patients (age, 3-17 years) who had congenital heart disease associated with severe pulmonary outflow obstruction. The BGS was used to volume-unload the pulmonary ventricle faced with residual outflow obstruction, thereby avoiding the need for insertion of a ventricle-to-pulmonary artery conduit. Transthoracic Doppler flow velocity analysis was used to determine transpulmonary peak systolic pressure drops as a measure of obstruction. Preoperative values ranged from 70 to 100 mmHg, and postoperative values ranged from less than 10 to 16 mmHg. At this writing, all patients are doing well 15 to 52 months after surgery. To gain further insight into the reduced pressure drop that may be achieved by decreasing flow rate across obstruction, a computer-based description of fluid flow was used to simulate blood traversing circumferentially narrowed passages. Overall pressure drops and associated flow energy losses were determined from numeric solutions (using finite-element analysis) to the Navier-Stokes equations for the proposed fluid reactions. Pressure drops and flow energy losses were found to decrease dramatically as flow rate was progressively reduced. For selected patients, a BGS can be an effective adjunct to the surgical treatment of pulmonary outflow obstruction. This approach avoids the use of a ventricle-to-pulmonary artery conduit, and thus the inevitable need in most patients for reoperations because of somatic growth, conduit failure, or both.
Asunto(s)
Procedimientos Quirúrgicos Cardíacos/métodos , Cardiopatías Congénitas/cirugía , Ventrículos Cardíacos/cirugía , Arteria Pulmonar/cirugía , Vena Cava Superior/cirugía , Obstrucción del Flujo Ventricular Externo/cirugía , Adolescente , Velocidad del Flujo Sanguíneo , Niño , Preescolar , Comorbilidad , Análisis de Elementos Finitos , Cardiopatías Congénitas/epidemiología , Humanos , Modelos Cardiovasculares , Tetralogía de Fallot/epidemiología , Tetralogía de Fallot/cirugía , Transposición de los Grandes Vasos/epidemiología , Transposición de los Grandes Vasos/cirugía , Obstrucción del Flujo Ventricular Externo/epidemiología , Presión VentricularRESUMEN
UNLABELLED: A case of a 5-month-old infant with complete duplication of the right leg and ipsilateral renal agenesis is presented. There was also a duplicated scrotum, posterior urethral valves with hydronephrosis, abnormal pelvic bones, and a ventricular septal defect. Complete caudal duplication is exceedingly rare. Associated defects are common. Several aetiological theories have been proposed. Among them, an underlying polytopic (acro-renal) developmental field defect has been suggested. It best explains the specific findings in our patient. However, the aetiology of caudal duplication syndromes may be multifactorial. In the light of twinning theories, associated duplication of hindgut derivates should be suspected in similar cases. Further research is needed. The motor-skeletal functional outcome after leg duplication surgery is mostly favourable. CONCLUSION: A case of complete unilateral leg duplication with ipsilateral renal agenesis is presented. It appears to support the theory of a polytopic developmental field defect.
Asunto(s)
Anomalías Múltiples , Riñón/anomalías , Pierna/anomalías , Defectos del Tabique Interventricular/etiología , Humanos , Hidronefrosis/etiología , Lactante , Masculino , Pelvis/anomalías , Vértebras Torácicas/anomalías , Reflujo Vesicoureteral/etiologíaRESUMEN
Chronic alveolar hypoxia induces vascular changes leading to pulmonary hypertension. We investigated the role of nitric oxide synthase (NOS) on basal pulmonary artery pressure (PAP) and on changes in PAP arising from an acute alveolar hypoxic challenge (AAHC) in normoxic and chronically hypoxic young rabbits. The chronically hypoxic rabbits were raised from birth in a chamber containing a (10% O2 + 90% N2) gas mixture, whereas the normoxic rabbits were kept in room air. The age of the animals at the time of study (approximately 38 days) was not significantly different between the 2 groups of rabbits. The in vivo PAP was measured using a right heart catheterization technique while the rabbits were spontaneously breathing either a hyperoxic or a hypoxic gas. In the chronically hypoxic group, the AAHC (hypoxic gas) produced a modest increase in PAP. However, after intravenous administration of (100 mg/kg) of the NOS inhibitor, L-NAME (N-nitro-L-arginine methyl ester), a marked increase in PAP was observed when these rabbits were rechallenged with the AAHC. In contrast, in the normoxic rabbits, the AAHC produced only a small increase in PAP, even after pretreatment with L-NAME. In both groups of rabbits, L-NAME led to a significant rise in basal PAP. Using Western blot analysis, we found endothelial NOS (eNOS) protein expression to be significantly increased in pulmonary artery and right ventricular myocardium of the chronically hypoxic rabbits. These results suggest that release of nitric oxide is involved in regulating basal PAP and in modulating the hypoxia-induced pulmonary vasoconstrictor response in immature animals. Moreover, eNOS appears to undergo up-regulation as a consequence of chronic hypoxia.
Asunto(s)
Hipoxia/fisiopatología , Pulmón/irrigación sanguínea , Pulmón/fisiopatología , Animales , Presión Sanguínea/efectos de los fármacos , Western Blotting , Inhibidores Enzimáticos/farmacología , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/enzimología , Hipertensión Pulmonar/fisiopatología , Pulmón/metabolismo , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/metabolismo , Óxido Nítrico Sintasa de Tipo III , Arteria Pulmonar/efectos de los fármacos , Arteria Pulmonar/enzimología , Conejos , Factores de TiempoRESUMEN
Isolated, paced, isovolumically beating, neonatal pig (n = 32) hearts underwent retrograde aortic perfusion with a solution containing insulin (100 microU/ml), glucose (5.5 mM), and palmitate (0.55 mM). Glycolysis, lactate release, glucose oxidation, palmitate oxidation, and oxygen consumption were assessed. The hearts were perfused during three periods: (1) baseline, pO(2) approximately 500 mm Hg, heart rate 150 bpm; (2) hypoxia, pO(2) approximately 60-80 mm Hg, heart rate 150 bpm, or tachycardia, pO(2) approximately 500 mm Hg, heart rate 300 bpm, and (3) recovery, return to baseline conditions. For hypoxia and tachycardia, the oxygen supply-demand ratio was comparable ( approximately 1 nmol O(2)/mm Hg/g(dry)). During baseline, the left ventricular peak systolic pressure (PSP) averaged 126 +/- 6 mm Hg, the end-diastolic pressure (EDP) 5 mm Hg, and the relaxation time constant (Tau) 34 +/- 2 ms; the coronary flow was 36 +/- 2 ml/min/g(dry). During hypoxia, the PSP decreased to 70 +/- 2 mm Hg, while EDP, Tau, and coronary flow increased to 26 +/- 2 mm Hg, 104 +/- 14 ms, and 70 +/- 2 ml/min/g(dry), respectively; palmitate oxidation and oxygen consumption decreased well below baseline. During tachycardia, the PSP decreased to 88 +/- 1 mm Hg, and the EDP increased to 11 +/- 1 mm Hg, while Tau and coronary flow did not change significantly; palmitate oxidation and oxygen consumption increased above baseline. For both stressors, the predicted lactate release underestimated the measured values by a factor of approximately 2, but were comparable during baseline and recovery. Upon recovery, PSP returned to approximately 80% of baseline, while EDP remained elevated, for both stressors. Glucose oxidation returned to baseline, but palmitate oxidation became accelerated. We conclude for neonatal pig hearts subjected to oxygen insufficiency: (1) that PSP decreases and (2) that EDP and Tau increase with hypoxia, whereas EDP increases, while Tau remains unchanged with tachycardia. Following both stressors, palmitate oxidation becomes enhanced and dissociated from mechanical activity.
Asunto(s)
Animales Recién Nacidos/fisiología , Corazón/fisiología , Oxígeno/administración & dosificación , Animales , Aorta , Presión Sanguínea , Circulación Coronaria , Diástole , Glucosa/administración & dosificación , Glucosa/metabolismo , Glucólisis , Frecuencia Cardíaca , Hipoxia , Técnicas In Vitro , Insulina/administración & dosificación , Ácido Láctico/metabolismo , Oxidación-Reducción , Consumo de Oxígeno , Ácido Palmítico/administración & dosificación , Ácido Palmítico/metabolismo , Perfusión , Soluciones , Porcinos , SístoleRESUMEN
BACKGROUND: Various pulmonary valve substitutes, with their inherent limitations, have been used in children and young adults. We chose the Medtronic Freestyle (Medtronics, Minneapolis, MN) valve because of its excellent hemodynamics, known durability in adults, and design features that allow modifications during implantation. METHODS: Over a 3 1/2 year period the Freestyle valve was implanted in 47 patients age 2 to 58 years (mean 14.2, median 12.0) in the pulmonary position. All patients had pulmonic stenosis and(or) insufficiency from previous operations for tetralogy (27), pulmonary atresia (6), truncus (4), or other diagnosis (10). The indication for surgery was pure pulmonary insufficiency in 11 patients, pulmonic stenosis in 3, and mixed stenosis and insufficiency in 33. Root replacement technique was used with additional enlargement of the pulmonary artery branches in 10 patients. RESULTS: Intraoperatively, one patient sustained a right ventricle tear and one a circumflex coronary artery injury during the dissection. There was one postoperative death. Two patients developed late subvalvular pannus formation, one of whom required reoperation. One patient was found to have an echo gradient of 95 mm Hg due to decreased leaflet motion and underwent cardiac catheterization at which the peak systolic gradient was determined to be 50 mm Hg. He has not required reintervention during his 3 1/2 years of follow-up. The remaining 43 patients have minimal gradients or insufficiency. All surviving patients are in New York Heart Association (NYHA) Class I. CONCLUSIONS: The Medtronic Freestyle valve is an attractive alternative for RVOT (right ventricular outflow tract) reconstruction in children. It is readily available, versatile, and has excellent hemodynamic characteristics. Although long term follow-up is not yet available, longevity of this prosthesis, and freedom from complications, will hopefully be superior to valves with stents.