RESUMEN
BACKGROUND: Type 2 diabetes (T2D) is associated with an increased risk of left ventricular dysfunction after aortic valve replacement (AVR) in patients with severe aortic stenosis (AS). Persistent impairments in myocardial energetics and myocardial blood flow (MBF) may underpin this observation. Using phosphorus magnetic resonance spectroscopy and cardiovascular magnetic resonance, this study tested the hypothesis that patients with severe AS and T2D (AS-T2D) would have impaired myocardial energetics as reflected by the phosphocreatine to ATP ratio (PCr/ATP) and vasodilator stress MBF compared with patients with AS without T2D (AS-noT2D), and that these differences would persist after AVR. METHODS: Ninety-five patients with severe AS without coronary artery disease awaiting AVR (30 AS-T2D and 65 AS-noT2D) were recruited (mean, 71 years of age [95% CI, 69, 73]; 34 [37%] women). Thirty demographically matched healthy volunteers (HVs) and 30 patients with T2D without AS (T2D controls) were controls. One month before and 6 months after AVR, cardiac PCr/ATP, adenosine stress MBF, global longitudinal strain, NT-proBNP (N-terminal pro-B-type natriuretic peptide), and 6-minute walk distance were assessed in patients with AS. T2D controls underwent identical assessments at baseline and 6-month follow-up. HVs were assessed once and did not undergo 6-minute walk testing. RESULTS: Compared with HVs, patients with AS (AS-T2D and AS-noT2D combined) showed impairment in PCr/ATP (mean [95% CI]; HVs, 2.15 [1.89, 2.34]; AS, 1.66 [1.56, 1.75]; P<0.0001) and vasodilator stress MBF (HVs, 2.11 mL min g [1.89, 2.34]; AS, 1.54 mL min g [1.41, 1.66]; P<0.0001) before AVR. Before AVR, within the AS group, patients with AS-T2D had worse PCr/ATP (AS-noT2D, 1.74 [1.62, 1.86]; AS-T2D, 1.44 [1.32, 1.56]; P=0.002) and vasodilator stress MBF (AS-noT2D, 1.67 mL min g [1.5, 1.84]; AS-T2D, 1.25 mL min g [1.22, 1.38]; P=0.001) compared with patients with AS-noT2D. Before AVR, patients with AS-T2D also had worse PCr/ATP (AS-T2D, 1.44 [1.30, 1.60]; T2D controls, 1.66 [1.56, 1.75]; P=0.04) and vasodilator stress MBF (AS-T2D, 1.25 mL min g [1.10, 1.41]; T2D controls, 1.54 mL min g [1.41, 1.66]; P=0.001) compared with T2D controls at baseline. After AVR, PCr/ATP normalized in patients with AS-noT2D, whereas patients with AS-T2D showed no improvements (AS-noT2D, 2.11 [1.79, 2.43]; AS-T2D, 1.30 [1.07, 1.53]; P=0.0006). Vasodilator stress MBF improved in both AS groups after AVR, but this remained lower in patients with AS-T2D (AS-noT2D, 1.80 mL min g [1.59, 2.0]; AS-T2D, 1.48 mL min g [1.29, 1.66]; P=0.03). There were no longer differences in PCr/ATP (AS-T2D, 1.44 [1.30, 1.60]; T2D controls, 1.51 [1.34, 1.53]; P=0.12) or vasodilator stress MBF (AS-T2D, 1.48 mL min g [1.29, 1.66]; T2D controls, 1.60 mL min g [1.34, 1.86]; P=0.82) between patients with AS-T2D after AVR and T2D controls at follow-up. Whereas global longitudinal strain, 6-minute walk distance, and NT-proBNP all improved after AVR in patients with AS-noT2D, no improvement in these assessments was observed in patients with AS-T2D. CONCLUSIONS: Among patients with severe AS, those with T2D demonstrate persistent abnormalities in myocardial PCr/ATP, vasodilator stress MBF, and cardiac contractile function after AVR; AVR effectively normalizes myocardial PCr/ATP, vasodilator stress MBF, and cardiac contractile function in patients without T2D.
Asunto(s)
Estenosis de la Válvula Aórtica , Diabetes Mellitus Tipo 2 , Implantación de Prótesis de Válvulas Cardíacas , Humanos , Femenino , Masculino , Válvula Aórtica/diagnóstico por imagen , Válvula Aórtica/cirugía , Diabetes Mellitus Tipo 2/complicaciones , Función Ventricular Izquierda/fisiología , Vasodilatadores , Adenosina Trifosfato , Implantación de Prótesis de Válvulas Cardíacas/efectos adversosRESUMEN
Traditionally, the management of type B aortic dissection has been the domain of the vascular surgeons. Timing and type of intervention still generate debate. We sought to review our early experience with the treatment of this condition based on a hybrid approach following an aortic multi-disciplinary team meeting involving close cooperation between cardiac surgeons, vascular surgeons, interventional radiologists, vascular anesthetists, and cardiac anesthetists. Four patients (age 41-56 years; 3 males; 1 female) with type B aortic dissection underwent aortic arch surgery through a hybrid approach: one elective procedure consisting of ascending aorta and hemi-arch replacement with debranching followed by thoracic endovascular aortic repair (TEVAR); one redo procedure requiring aortic arch replacement with hybrid frozen elephant trunk; two acute presentations (aortic arch replacement and debranching followed by TEVAR; AVR with ascending aorta, arch, and proximal descending thoracic aorta replacement with conventional elephant trunk and debranching). Deep hypothermic circulatory arrest was required in three patients. Despite respiratory complications and slightly prolonged postoperative course, all patients survived without onset of stroke, paraplegia, malperfusion, endoleak, or need for re-exploration. Follow-up remains satisfactory. Different factors may affect outcome following complex aortic procedures. Nevertheless, close cooperation between cardiac surgeons, vascular surgeons, and interventional radiologists may reduce potential for complications and address aspects that may not be completely within the domain of individual specialists.
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Importance: Transcatheter aortic valve implantation (TAVI) is a less invasive alternative to surgical aortic valve replacement and is the treatment of choice for patients at high operative risk. The role of TAVI in patients at lower risk is unclear. Objective: To determine whether TAVI is noninferior to surgery in patients at moderately increased operative risk. Design, Setting, and Participants: In this randomized clinical trial conducted at 34 UK centers, 913 patients aged 70 years or older with severe, symptomatic aortic stenosis and moderately increased operative risk due to age or comorbidity were enrolled between April 2014 and April 2018 and followed up through April 2019. Interventions: TAVI using any valve with a CE mark (indicating conformity of the valve with all legal and safety requirements for sale throughout the European Economic Area) and any access route (n = 458) or surgical aortic valve replacement (surgery; n = 455). Main Outcomes and Measures: The primary outcome was all-cause mortality at 1 year. The primary hypothesis was that TAVI was noninferior to surgery, with a noninferiority margin of 5% for the upper limit of the 1-sided 97.5% CI for the absolute between-group difference in mortality. There were 36 secondary outcomes (30 reported herein), including duration of hospital stay, major bleeding events, vascular complications, conduction disturbance requiring pacemaker implantation, and aortic regurgitation. Results: Among 913 patients randomized (median age, 81 years [IQR, 78 to 84 years]; 424 [46%] were female; median Society of Thoracic Surgeons mortality risk score, 2.6% [IQR, 2.0% to 3.4%]), 912 (99.9%) completed follow-up and were included in the noninferiority analysis. At 1 year, there were 21 deaths (4.6%) in the TAVI group and 30 deaths (6.6%) in the surgery group, with an adjusted absolute risk difference of -2.0% (1-sided 97.5% CI, -∞ to 1.2%; P < .001 for noninferiority). Of 30 prespecified secondary outcomes reported herein, 24 showed no significant difference at 1 year. TAVI was associated with significantly shorter postprocedural hospitalization (median of 3 days [IQR, 2 to 5 days] vs 8 days [IQR, 6 to 13 days] in the surgery group). At 1 year, there were significantly fewer major bleeding events after TAVI compared with surgery (7.2% vs 20.2%, respectively; adjusted hazard ratio [HR], 0.33 [95% CI, 0.24 to 0.45]) but significantly more vascular complications (10.3% vs 2.4%; adjusted HR, 4.42 [95% CI, 2.54 to 7.71]), conduction disturbances requiring pacemaker implantation (14.2% vs 7.3%; adjusted HR, 2.05 [95% CI, 1.43 to 2.94]), and mild (38.3% vs 11.7%) or moderate (2.3% vs 0.6%) aortic regurgitation (adjusted odds ratio for mild, moderate, or severe [no instance of severe reported] aortic regurgitation combined vs none, 4.89 [95% CI, 3.08 to 7.75]). Conclusions and Relevance: Among patients aged 70 years or older with severe, symptomatic aortic stenosis and moderately increased operative risk, TAVI was noninferior to surgery with respect to all-cause mortality at 1 year. Trial Registration: isrctn.com Identifier: ISRCTN57819173.
Asunto(s)
Estenosis de la Válvula Aórtica , Reemplazo de la Válvula Aórtica Transcatéter , Anciano , Anciano de 80 o más Años , Válvula Aórtica/cirugía , Insuficiencia de la Válvula Aórtica/etiología , Estenosis de la Válvula Aórtica/mortalidad , Estenosis de la Válvula Aórtica/cirugía , Femenino , Prótesis Valvulares Cardíacas , Implantación de Prótesis de Válvulas Cardíacas/efectos adversos , Implantación de Prótesis de Válvulas Cardíacas/métodos , Implantación de Prótesis de Válvulas Cardíacas/mortalidad , Humanos , Masculino , Factores de Riesgo , Reemplazo de la Válvula Aórtica Transcatéter/efectos adversos , Reemplazo de la Válvula Aórtica Transcatéter/mortalidad , Resultado del TratamientoRESUMEN
BACKGROUND: Penetrating ulcers of aorta, aortic dissections and intramural hematomas all come under acute aortic syndromes and have important similarities and differences. CASE REPORT: We report a 67 year old man with rupture of a large penetrating ulcer of the distal ascending aorta with hemopericardium and left hemothorax. He underwent interposition graft replacement of ascending aorta and hemi-arch with a 30 mm Gelweave Vascutek graft but represented 6 months later with development of a penetrating ulcer which ruptured into a huge 14 cm pseudoaneurysm. This was repaired with a 28 mm Vascutek Gelseal graft replacement of arch and interposition graft reconstruction of innominate and left common carotid arteries. 6 weeks later, however, he ruptured his proximal descending aorta and underwent TEVAR satisfactorily. Unfortunately, 2 days later, he developed a pathological fracture of left proximal tibia with metastasis from a primary renal cell carcinoma. He died 3 weeks later from respiratory failure. We shall briefly outline the similarities and differences in presentation and management of penetrating aortic ulcers, aortic dissections and intramural haematomas. We shall discuss, in greater detail, penetrating ulcers of thoracic aorta, their natural history, location, complications and management. CONCLUSION: This case report is unique on account of initial successful surgical redressal following rupture of penetrating ulcer of distal ascending aorta into left pleural and pericardial cavities, normally associated with instant death. The haemodynamic effects of the rupture were staggered due to initial contained rupture into a smaller pseudoaneurysm, followed by a further rupture into a false aneurysmal sac followed eventually by generalised rupture into the pleural and pericardial cavities - a unique way of aortic rupture. Further development of another penetrating ulcer and a small pseudoaneurysm in the distal arch 6 months later which further ruptured into a larger 14 cm false aneurysmal sac, which again did not result in exsanguination, is again extraordinarily rare. Thereafter he underwent emergency thoracic endovascular aortic repair (TEVAR) for a further rupture of descending thoracic aorta. All three ruptures were managed successfully and would usually be associated with near-certain death, only for the patient to succumb eventually to the complications of metastatic renal cell carcinoma.
Asunto(s)
Enfermedades de la Aorta/complicaciones , Rotura de la Aorta/etiología , Aterosclerosis/complicaciones , Úlcera/complicaciones , Anciano , Disección Aórtica/cirugía , Aorta/cirugía , Aorta Torácica/cirugía , Enfermedades de la Aorta/cirugía , Rotura de la Aorta/cirugía , Prótesis Vascular , Carcinoma de Células Renales/complicaciones , Carcinoma de Células Renales/patología , Hemotórax/etiología , Humanos , Neoplasias Renales/complicaciones , Neoplasias Renales/patología , Masculino , Metástasis de la Neoplasia , Derrame Pericárdico/etiología , Úlcera/cirugía , Procedimientos Quirúrgicos VascularesRESUMEN
OBJECTIVES: Surgery is often required for acute infective endocarditis (IE) to repair or replace damaged heart valves. Traditionally, long courses of antibiotic treatment have been prescribed after surgery for active IE for fear of infecting newly implanted/repaired valves, but the need for this, in the present era of enhanced antimicrobial stewardship, has been questioned. In our institution, the choice and duration of antimicrobial therapy is tailored to individual patients by a multidisciplinary team with an interest in IE. The influence of the duration of postoperative antibiotic therapy on outcomes was studied in patients requiring surgery prior to the completion of a planned course of antibiotic therapy. METHODS: This was a retrospective observational study on patients with acute IE requiring surgery between January 2004 and December 2015. The primary outcome was relapse. Secondary outcomes were early reoperation and 1-year mortality. RESULTS: In total, 182 IE episodes were included in the final analysis. The median duration of postoperative antibiotic therapy was 23.5 days (interquartile range 12-40 days) and decreased significantly during the period of study (P < 0.001). There were 2 relapses (1.1%) and 18 (9.9%) postoperative deaths within 1 year. Nine (5%) patients underwent early reoperation. The duration of postoperative antibiotic therapy did not affect either the primary or the secondary outcomes. CONCLUSIONS: This work supports previous findings that selected patients who require surgery during active IE can be safely given shorter courses of postoperative antibiotics without an impact on relapse of infection or survival.
Asunto(s)
Antibacterianos/uso terapéutico , Endocarditis/cirugía , Adulto , Anciano , Antibacterianos/administración & dosificación , Procedimientos Quirúrgicos Cardíacos/efectos adversos , Procedimientos Quirúrgicos Cardíacos/métodos , Procedimientos Quirúrgicos Cardíacos/mortalidad , Endocarditis/tratamiento farmacológico , Endocarditis/mortalidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Cuidados Posoperatorios/métodos , Recurrencia , Reoperación/mortalidad , Reoperación/estadística & datos numéricos , Estudios Retrospectivos , Prevención Secundaria/métodos , Resultado del TratamientoRESUMEN
BACKGROUND: Deep sternal wound complications are uncommon after cardiac surgery. They comprise sternal dehiscence, deep sternal wound infections and mediastinitis, which will be treated as varying expressions of a singular pathology for reasons explained in the text. METHODOLOGY AND REVIEW: This article reviews the definition, prevalence, risk factors, prevention, diagnosis, microbiology and management of deep sternal wound infections and mediastinitis after cardiac surgery. The role of negative pressure wound therapy and initial and delayed surgical management is discussed with special emphasis on plastic techniques with muscle and omental flaps. Recent advances in reconstructive surgery are presented. CONCLUSIONS: Deep sternal wound complications no longer spell debilitating morbidity and high mortality. Better understanding of risk factors that predispose to deep sternal wound complications and general improvement in theatre protocols for asepsis have dramatically reduced the incidence of deep sternal wound complications. Negative pressure wound therapy and appropriately timed and staged muscle or omental flap reconstruction have transformed the outcomes once these complications occur.
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Procedimientos Quirúrgicos Cardíacos/efectos adversos , Mediastinitis/cirugía , Esternotomía/efectos adversos , Esternón/cirugía , Colgajos Quirúrgicos , Infección de la Herida Quirúrgica/cirugía , Toracoplastia/métodos , Humanos , Mediastinitis/etiología , Infección de la Herida Quirúrgica/etiologíaRESUMEN
Ascending aorta pseudoaneurysm (AAPA) is an uncommon complication following replacement of the ascending aorta with a prosthetic graft, carry a high risk of rupture, and warrant urgent intervention. The open surgical procedure "gold standard" of care is not always favorable, as the reoperations are technically more difficult or patient's general condition doesn't allow proceeding. Case discussed is an 80-year-old male patient who presented with worsening cough and hemoptysis. He underwent ascending aorta replacement 10 years ago. Computed tomography (CT) scan revealed a contrast-filled mediastinal mass communicating with the ascending aorta and extended into the right lung. Due to the patient's advanced age, friability and clinical condition, combined with the position of the AAPA behind the sternum, surgery was deemed to be high risk. However, favorable anatomical conditions provided a safe landing zone for an endovascular stent. The patient underwent closed procedure. Postprocedure CT showed complete obliteration of the AAPA.
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Aneurisma Falso/cirugía , Aorta/cirugía , Aneurisma de la Aorta/cirugía , Implantación de Prótesis Vascular/efectos adversos , Procedimientos Endovasculares , Técnicas de Sutura/efectos adversos , Anciano de 80 o más Años , Aneurisma Falso/diagnóstico , Aneurisma Falso/etiología , Angiografía de Substracción Digital , Aneurisma de la Aorta/diagnóstico , Aneurisma de la Aorta/etiología , Aortografía/métodos , Prótesis Vascular , Procedimientos Endovasculares/instrumentación , Humanos , Masculino , Tomografía Computarizada Multidetector , Reoperación , Stents , Factores de Tiempo , Resultado del TratamientoRESUMEN
A 56 year old Caucasian man presented with sudden loss of consciousness while driving and was found to have an 11 cm Haughton D type left cervical aortic arch aneurysm with normal brachiocephalic branching and normal descending thoracic laterality but with considerable tortuosity and redundancy of aortic arch. The aneurysm arose between the left common carotid artery and the left subclavian artery. It compressed and stretched the left common carotid artery, compressed the pulmonary trunk and the left pulmonary artery, stretched the vagus, left recurrent laryngeal and left phrenic nerves and caused extreme deviation of trachea, severely compromising the tracheal lumen. Patient underwent successful interposition graft replacement of distal aortic arch under total circulatory arrest and selective unihemispherical cerebral perfusion.
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Aorta Torácica/patología , Aorta Torácica/cirugía , Aneurisma de la Aorta/patología , Aneurisma de la Aorta/cirugía , Aorta Torácica/diagnóstico por imagen , Aneurisma de la Aorta/diagnóstico por imagen , Prótesis Vascular , Implantación de Prótesis Vascular , Procedimientos Quirúrgicos Cardíacos , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Radiografía TorácicaRESUMEN
We present the case of a 68 year old Caucasian woman, in extremis, with left hemiparesis and right hemothorax, in hypovolemic shock, secondary to a blow-out of a large penetrating ulcer at the junction of innominate trunk and aortic arch. She underwent interposition graft replacement of innominate trunk and repair of aortic arch, on cardiopulmonary bypass, employing total circulatory arrest and selective antegrade cerebral perfusion and had total resolution of hemiparesis. She, however, represented, 6 months later, with threatened exsanguination after a sternal wire cheese-wired through the sternum and perforated the anteriorly lying innominate graft. Following successful repair, she was found to have an old intramural hematoma of distal arch and descending thoracic aorta and changes suggestive of chronic dissection of the whole of abdominal aorta. This was managed conservatively.We believe this patient's presentation initially with a spontaneous innominate blow-out, cardiogenic shock, hemothorax and hemiparesis, and later with cheese-wire perforation of the innominate graft is unique. Her surgical rescue at both presentations was equally unusual, and without surgical precedent to the best of our knowledge. Was the initial innominate blow-out the result of localised innominate dissection, or more unusually, part of retrograde descending thoracic dissection with skip penetration of innominate artery and sparing of the intervening arch? Was it secondary to the minor fall she had sustained 1 week prior to the event, resulting in a false aneurysm or a contained hematoma next to the innominate artery? More intriguingly, did diffuse aortopathy underpin these diverse etiologies and result in penetrating intimal ulcer with blow out in the innominate artery, intramural hematoma in the arch and descending thoracic aorta and dissection in abdominal aorta at different points in time?We review the current literature for these unusual afflictions of innominate trunk and its origin from the arch of aorta.
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Implantación de Prótesis Vascular/métodos , Tronco Braquiocefálico/lesiones , Tronco Braquiocefálico/cirugía , Hemotórax/complicaciones , Hemotórax/cirugía , Paresia/complicaciones , Dispositivos de Fijación Quirúrgicos/efectos adversos , Anciano , Aorta Torácica/cirugía , Implantación de Prótesis Vascular/efectos adversos , Puente Cardiopulmonar , Femenino , Humanos , Falla de Prótesis , Tomografía Computarizada por Rayos XRESUMEN
We describe sole direct innominate cannulation for arterial return for establishing both cardiopulmonary bypass and selective antegrade cerebral perfusion in the repair of acute type A dissection and compare it with femoral, axillary, direct aortic and apical cannulations. We believe innominate cannulation has all the advantages of right axillary cannulation and none of its disadvantages. It can be used in all patients in whom innominate artery is not dissected, obstructed, calcified or otherwise diseased.
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Aneurisma de la Aorta/cirugía , Disección Aórtica/cirugía , Tronco Braquiocefálico/cirugía , Cateterismo/métodos , Humanos , EsternotomíaRESUMEN
A 56-year-old man with sudden onset chest pain, absent right lower limb pulses and ECG changes suggestive of inferior ST elevation MI underwent coronary angiogram through the right radial artery with a view to primary percutaneous coronary intervention (PCI). The left coronary angiogram demonstrated severe proximal stenotic disease in the left anterior descending and circumflex coronary arteries, but the right coronary artery could not be selectively cannulated. An ascending aortogram to visualise the right coronary artery not only failed to demonstrate it, but revealed, instead, a dissection flap in the ascending aorta, arch and descending thoracic aorta, with moderately severe aortic regurgitation. At operation, the patient was found to have an acute dissection of the ascending aorta, arch and descending aorta with an entry tear in the descending aorta below the left subclavian artery origin. Triple coronary artery bypass grafting with re-suspension of the aortic valve, supracoronary replacement of the ascending aorta and hemiarch and transaortic repair of the descending aortic tear was performed. The patient made an uncomplicated recovery, with the re-appearance of right limb pulses. A postoperative magnetic resonance (MR) scan revealed complete thrombosis of the false channel in the residual arch and a considerably shrunken false channel in the descending aorta and no aortic regurgitation. Retrograde dissection of the ascending aorta from the descending aorta has been reported infrequently in the past. We believe the scale of the problem has been underestimated because of the failure to adopt open distal anastomosis routinely in the past and, hence, failure to inspect the arch and the descending aorta routinely, particularly when the intimal tear was not identified in the ascending aorta. Retrograde dissection of the ascending aorta from an intimal tear in the descending aorta, when identified as such, has been managed, either on the principle of exclusion of the tear in the descending aorta by various elephant trunk procedures and their variants or, alternatively, on the principle of excision of the tear by extended one-stage aortic replacement, usually combined with an elephant trunk procedure. Neither of these procedures is widely adopted, owing to procedural, institutional and outcome considerations. We describe a transaortic repair of the intimal tear in the descending aorta with supracoronary interposition graft replacement of the ascending aorta and hemiarch with excellent clinical and radiological result. We also review the diagnostic and therapeutic approaches to this incompletely understood lethal disease.
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Aorta Torácica/cirugía , Puente de Arteria Coronaria/métodos , Complicaciones Posoperatorias/diagnóstico , Complicaciones Posoperatorias/cirugía , Rotura Espontánea/diagnóstico , Rotura Espontánea/cirugía , Trombosis/diagnóstico , Trombosis/cirugía , Aorta Torácica/diagnóstico por imagen , Angiografía Coronaria/métodos , Humanos , Angiografía por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Complicaciones Posoperatorias/etiología , Trombosis/etiologíaRESUMEN
This paper reports dependency of specific heat and ballistic thermal conductance on cross-sectional geometry (tube versus rod) and size (i.e., diameter and wall thickness), in free-standing isotropic non-metallic crystalline nanostructures. The analysis is performed using dispersion relations found by numerically solving the Pochhammer-Chree frequency equation for a tube. Estimates for the allowable phonon dispersion relations within the crystal lattice are obtained by modifying the elastic acoustic dispersion relations so as to account for the discrete nature of the material's crystal lattice. These phonon dispersion relations are then used to evaluate the specific heat and ballistic thermal conductance in the nanostructures as a function of the nanostructure geometry and size. Two major results are revealed in the analysis: increasing the outer diameter of a nanotube while keeping the ratio of the inner to outer tube radius (gamma) fixed increases the total number of available phonon modes capable of thermal population. Secondly, decreasing the wall thickness of a nanotube (i.e., increasing gamma) while keeping its outer diameter fixed, results in a drastic decrease in the available phonon mode density and a reduction in the frequency of the longitudinal and flexural acoustic phonon modes in the nanostructure. The dependency of the nanostructure's specific heat on temperature indicates 1D, 2D, and 3D geometric phonon confinement regimes. Transition temperatures for each phonon confinement regime are shown to depend on both the nanostructure's wall thickness and outer radius. Compared to nanowires (gamma = 0), the frequency reduction of acoustic phonon modes in thinner walled nanotubes (gamma = 0.96) is shown to elevate the ballistic thermal conductance of the thin-walled nanotube between 0.2 and 150 K. At 20 K, the ballistic thermal conductance of the thin-walled nanotube (gamma = 0.96) becomes 300% greater than that of a solid nanowire. For temperatures above 150 K, the trend in ballistic thermal conductance inverts. The greater number of phonon modes in nanostructures with increased outer diameter and wall thickness is shown to have a larger contribution to ballistic thermal conductance when compared to the increased contribution from the frequency reduction of acoustic phonon modes in thinner walled nanotubes.
RESUMEN
Coexistence of coronary artery disease and cancer with both requiring surgical treatment at the same time is rare. A 52 year male undergoing elective coronary artery bypass grafting was incidentally discovered to have a large soft tissue mass of variable consistency with cartilaginous elements arising from the right costal margin and adjoining ribs by a broad attachment and protruding into right pleural cavity. Frozen section suggested it to be either a chondrosarcoma or a teratoma. A wide excision of the mass with the adjoining muscle and periosteum along with quadruple coronary artery bypass grafting was done. This report is unusual on account of a) being the first reported case in world literature of concomitant excision of chondrosarcoma and coronary artery bypass grafting and b) the conservative management of the incidentally discovered chondrosarcoma by wide excision rather than chest wall resection with no local recurrence to date. Pathology of chondrosarcoma, in particular, and various management strategies when coronary artery disease and cancer coexist, in general, is discussed.
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Neoplasias Óseas/cirugía , Condrosarcoma/cirugía , Puente de Arteria Coronaria/métodos , Enfermedad de la Arteria Coronaria/cirugía , Costillas , Neoplasias Óseas/complicaciones , Neoplasias Óseas/patología , Condrosarcoma/complicaciones , Condrosarcoma/patología , Enfermedad de la Arteria Coronaria/complicaciones , Humanos , Hallazgos Incidentales , Masculino , Persona de Mediana Edad , Resultado del TratamientoRESUMEN
A 59 year old man underwent mechanical tricuspid valve replacement and removal of pacemaker generator along with 4 pacemaker leads for pacemaker endocarditis and superior vena cava obstruction after an earlier percutaneous extraction had to be abandoned, 13 years ago, due to cardiac arrest, accompanied by silent, unsuspected right atrial perforation and exteriorisation of lead. Postoperative course was complicated by tricuspid valve thrombosis and secondary pulmonary embolism requiring TPA thrombolysis which was instantly successful. A review of literature of pacemaker endocarditis and tricuspid thrombosis along with the relevant management strategies is presented. We believe this case report is unusual on account of non operative management of right atrial lead perforation following an unsuccessful attempt at percutaneous removal of right sided infected pacemaker leads and the incidental discovery of the perforated lead 13 years later at sternotomy, presentation of pacemaker endocarditis with a massive load of vegetations along the entire pacemaker lead tract in superior vena cava, right atrial endocardium, tricuspid valve and right ventricular endocardium, leading to a functional and structural SVC obstruction, requirement of an unusually large dose of warfarin postoperatively occasioned, in all probability, by antibiotic drug interactions, presentation of tricuspid prosthetic valve thrombosis uniquely as vasovagal syncope and isolated hypoxia and near instantaneous resolution of tricuspid prosthetic valve thrombosis with Alteplase thrombolysis.
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Endocarditis/cirugía , Marcapaso Artificial/efectos adversos , Embolia Pulmonar/cirugía , Síndrome de la Vena Cava Superior/cirugía , Trombosis/cirugía , Infección de Heridas/cirugía , Adulto , Remoción de Dispositivos/efectos adversos , Remoción de Dispositivos/métodos , Endocarditis/complicaciones , Falla de Equipo , Atrios Cardíacos/lesiones , Prótesis Valvulares Cardíacas , Humanos , Masculino , Persona de Mediana Edad , Embolia Pulmonar/complicaciones , Reoperación , Trombosis/complicaciones , Resultado del Tratamiento , Válvula Tricúspide , Infección de Heridas/complicacionesRESUMEN
A 66 year old woman presented in extremis with symptoms and clinical and radiological signs of simultaneous obstruction of superior vena cava and middle lobe of right lung secondary to compression by a massive benign anterior mediastinal cyst. Excision of the cyst at median sternotomy resulted in complete resolution of all symptoms. This report is unusual on account of a) the concomitant presence of superior vena cava and middle lobe syndromes caused by a benign cyst because of its sheer size producing obstruction of these structures and b) the complete resolution of all symptoms and signs after removal of the cyst. Benign anterior mediastinal cysts are unknown to cause either of the two syndromes. To our knowledge, it is the first report of a benign anterior mediastinal cyst causing either superior vena cava syndrome or middle lobe syndrome or both simultaneously. Etiologies of both superior vena cava and middle lobe syndromes are discussed in detail.
Asunto(s)
Quiste Mediastínico/complicaciones , Síndrome del Lóbulo Medio/diagnóstico , Síndrome de la Vena Cava Superior/etiología , Anciano , Broncoscopía , Diagnóstico Diferencial , Ecocardiografía Transesofágica , Femenino , Estudios de Seguimiento , Humanos , Imagen por Resonancia Magnética , Quiste Mediastínico/diagnóstico , Quiste Mediastínico/cirugía , Síndrome del Lóbulo Medio/cirugía , Síndrome de la Vena Cava Superior/diagnóstico , Síndrome de la Vena Cava Superior/cirugía , Procedimientos Quirúrgicos Torácicos/métodos , Tomografía Computarizada por Rayos XRESUMEN
We describe, in a 61 year old man, with coexistent aortic stenosis, the anomalous origin of posterior descending artery (PDA) from a stenotic left anterior descending (LAD) artery, as its continuation across the left ventricular apex, in the presence of a normally arising and atretic proximal right coronary artery. The patient underwent mechanical aortic valve replacement and triple coronary artery bypass grafting and made an uneventful recovery. To the best of our knowledge, origin of PDA as a continuation of LAD across the left ventricular apex in the presence of a normally arising but atretic proximal right coronary artery has never been described in literature before. There is one previous case report of continuation of LAD as PDA across the left ventricular apex in a patient with single left coronary coronary artery with an absent right coronary ostium. As the blood supply to the entire interventricular septum is derived from this "hyperdominant" LAD system, stenosis of LAD can be catastrophic. A review of literature of the anomalies of right coronary artery and, in particular, of its anomalous origin from LAD and its coexistence with aortic stenosis, is presented.
Asunto(s)
Estenosis de la Válvula Aórtica/complicaciones , Válvula Aórtica/cirugía , Puente de Arteria Coronaria , Anomalías de los Vasos Coronarios/complicaciones , Implantación de Prótesis de Válvulas Cardíacas , Angiografía , Estenosis de la Válvula Aórtica/diagnóstico , Estenosis de la Válvula Aórtica/cirugía , Angiografía Coronaria , Anomalías de los Vasos Coronarios/diagnóstico , Anomalías de los Vasos Coronarios/cirugía , Prótesis Valvulares Cardíacas , Humanos , Masculino , Persona de Mediana Edad , Diseño de PrótesisRESUMEN
A 61 year old man presented with diffuse large B cell lymphoma of the skin of the back of the shoulder which was excised and treated with chemotherapy (CHOP regime) in 1998. He was in complete remission till he presented in 2002 with extranodal marginal zone lymphoma of the parotid gland for which he underwent superficial parotidectomy and radiotherapy. He continued in remission till 2006 when he presented with recurrent pericardial effusion and tamponade. At median sternotomy, pericardial effusion was drained, an anterior pericardiectomy was done and a left posterior pericardial window made, and an enlarged hard paraaortic lymph node excised. Histology, immunocytochemistry and chromosome analysis revealed Burkitt lymphoma. Patient underwent chemotherapy with CODOX-M regime and continues in remission. This report is unusual on account of the highly atypical presentation of Burkitt lymphoma as cardiac tamponade, only a few cases having been reported previously, the occurrence of three lymphomas of different pathological and genomic profiles in one patient over a period of eight years and the relatively slow rate of growth of an otherwise fulminant tumour with high tumour doubling time. A review of literature with special emphasis on chromosomal diagnosis, transformation of other lymphomas into Burkitt lymphoma and mediastinal and cardiac involvement with Burkitt lymphoma is presented.
Asunto(s)
Linfoma de Burkitt/diagnóstico , Taponamiento Cardíaco/diagnóstico , Diagnóstico Diferencial , Humanos , Masculino , Persona de Mediana EdadRESUMEN
A single left coronary artery with right coronary artery arising from either left main stem (LMS) or left anterior descending artery (LAD) or circumflex artery (Cx) is an extremely rare coronary anomaly. This is the first report of separate origins of proximal and distal RCA from LAD and circumflex arteries respectively in a patient with a single left coronary artery. This 57 year old patient presented with unstable angina and severe stenotic disease of LAD and Cx arteries and underwent urgent successful quadruple coronary artery bypass grafting. The anomalies of right coronary artery in terms of their origin, number and distribution are reviewed.
Asunto(s)
Puente de Arteria Coronaria/métodos , Circulación Coronaria/fisiología , Estenosis Coronaria/diagnóstico por imagen , Estenosis Coronaria/cirugía , Anomalías de los Vasos Coronarios/diagnóstico por imagen , Anomalías Múltiples/diagnóstico por imagen , Anomalías Múltiples/cirugía , Angina Inestable/diagnóstico , Angina Inestable/etiología , Puente Cardiopulmonar/métodos , Angiografía Coronaria , Estenosis Coronaria/fisiopatología , Anomalías de los Vasos Coronarios/cirugía , Estudios de Seguimiento , Humanos , Angiografía por Resonancia Magnética , Masculino , Persona de Mediana Edad , Enfermedades Raras , Medición de Riesgo , Índice de Severidad de la Enfermedad , Resultado del TratamientoRESUMEN
A 58 year old man underwent 6 surgical interventions for various complications of massive biventricular myocardial infarction over a period of 2 years following acute occlusion of a possibly "hyperdominant" left anterior descending coronary artery. These included concomitant repair of apicoanterior post-infarction VSD and right ventricular free wall rupture, repeat repair of recurrent VSD following inferoposterior extension of VSD in the infarcted septum 5 weeks later, repair of delayed right ventricular free wall rupture 4 weeks subsequently, repair of a bleeding left ventricular aneurysm eroding through left chest wall 16 months thereafter, repair of right upper lobe lung tear causing massive anterior mediastinal haemorrhage, mimicking yet another cardiac rupture, 2 months later, followed, at the same admission, 2 weeks later, by sternal reconstruction for dehisced and infected sternum using pedicled myocutaneous latissimus dorsi flap. 5 years after the latissimus myoplasty, the patient remains in NYHA class 1 and is leading a normal life.