Management of a Compromised Frozen Elephant Trunk Due to Acute Type B Aortic Dissection.

PURPOSE: To report a case who required a thoracic endovascular stenting (TEVAR) following the deployment of frozen elephant trunk due to false lumen expansion. CASE REPORT: A 47 years old male patient undergone emergency repair of acute type A aortic dissection in 2011 with bioprosthetic aortic root conduit. Seven years later he presented with moderate aortic valve disease and expanding chronic dissection of the aortic arch, therefore a redo operation with replacement of the prosthetic aortic valve, ascending aorta, total arch and deployment of frozen elephant trunk and he was discharged in good health. Several days post discharge he presented with new onset of chest pain and a new dissection involved the thoracoabdominal aorta was noted pressing on the true lumen and the frozen elephant trunk. Following a multi-disciplinary team meeting, TEVAR was deemed as a most appropriate approach and this was achieved successfully, and patient was discharged. At 1 year of follow up, he remains well and asymptomatic. CONCLUSION: Close imaging follow-up following deployment of a FET is mandatory. A new acute Type B aortic dissection distal to the FET, that causes false lumen propagation parallel to the stented portion, is a surgical emergency and further intervention mandated.

Setting up and utilizing a service for measuring perioperative transcranial motor evoked potentials during thoracoabdominal aortic surgery and thoracic endovascular repair.

OBJECTIVES: Paraplegia is a complication that may occur following surgery or endovascular stenting of thoracic and thoracoabdominal aortic pathology. Measuring transcranial motor evoked potentials (tcMEPs) has been shown to provide a reliable measure of spinal cord function during such procedures allowing interventions to protect cord function. In the spirit of sharing experience and eliminating the learning curve for others, this manuscript describes our experience of setting up a service for tcMEP monitoring as well as the documents and algorithms for measuring, recording and acting on the patient data, the so-called 'MEP Pathway'. METHODS: Recording and interpretation of tcMEP during thoracoabdominal aortic intervention requires training of staff and close team working in the operating theatre and postoperative intensive care unit. Providing consistent, reliable, specific and sensitive information on spinal cord function and its safe and effective use to alter patient outcomes requires a protocol. The MEP pathway was developed by medical and paramedical staff at our institution based on clinical experience and literature reviews over a 1-year period (2012-2013). RESULTS: The tcMEP pathway comprises six documents that guide staff in: (a) assessing suitability of patients, (b) setting up hardware, (c) preparing algorithms for management, (d) documenting intervention (left heart bypass, cardiopulmonary bypass or endovascular stenting) as well as (e) documenting postoperative intensive care processes. CONCLUSIONS: The tcMEP pathway acts as a guide for safe introduction and use of tcMEPs in thoracoabdominal aortic interventions. tcMEP-led guidance of intraoperative and postoperative management in thoracic aortic surgery is an important adjunct in caring for this patient group.

Novel application of acetazolamide to reduce cerebrospinal fluid production in patients undergoing thoracoabdominal aortic surgery.

OBJECTIVES: Paraplegia is a rare but devastating complication, which may follow thoracoabdominal aortic surgery. Many adjuncts have been developed to reduce this risk including cerebrospinal fluid (CSF) drainage. Acetazolamide (carbonic anhydrase inhibitor) is a drug used to counteract mountain sickness and one of its effects is to reduce CSF production. Here, we report its first postoperative application in thoracoabdominal surgery with the aim of reducing cerebrospinal cord perfusion pressure and reducing risk of paraplegia. METHODS: We retrospectively reviewed 6 patients who have been treated with this drug between 2011 and 2012 who were undergoing thoracoabdominal aortic surgery. Our indications were decided to include: (i) patients in whom a spinal drain could not be positioned; (ii) patients with blood-stained CSF; (iii) patients in whom the volume of CSF drained was outside guidelines; (iv) patients in whom CSF pressure was elevated; (v) patients with excessive vasopressor usage and (vi) patients with postoperative neurological dysfunction as measured by motor-evoked potentials or clinical examination. All were given 500 mg intravenous acetazolamide, not more than eight hourly, for a duration dependent on response. RESULTS: In the 6 patients, 2 received a single dose of the drug and responded by an immediate drop in intracranial pressure (ICP) pressure. Of the 4 who received multiple doses of the drug, 1 had an immediate decline in ICP after each of the first six doses, while 3 had no discernable response. CONCLUSIONS: This is the first report of the efficacy of acetazolamide in reducing CSF production and lowering ICP during thoracoabdominal aortic surgery. We believe that its use will be beneficial in the 6 patient groups described. Our experience suggests there are 'responders' and 'non-responders', the characteristics of whom are yet to be defined. Its efficacy in reducing not just CSF volume and ICP but also clinically relevant morbidity such as paraplegia, is the subject of a planned randomized controlled trial. This report serves to raise awareness of the possible efficacy of this drug when normal management strategies are limited or exhausted.

Combined cardiac surgery and endovascular repair of abdominal aortic aneurysms.

PURPOSE: To report an initial experience of concomitant endovascular repair of abdominal aortic aneurysms (AAA) and cardiac surgery. METHODS: Records for 10 consecutive patients (all men; median age 68 years, range 60-79) with AAA treated by a multidisciplinary team at a tertiary specialist center were retrospectively reviewed. Each patient had independent indications for surgical correction of their cardiac disease and AAAs. The patients underwent endovascular aneurysm repair (EVAR) followed by cardiac surgery under the same anesthesia. Eight patients had concomitant coronary artery bypass grafting (CABG; 4 off-pump), 1 patient had CABG and left ventricular aneurysmectomy, and 1 patient required aortic root replacement. RESULTS: All combined procedures were performed successfully under a single general anesthesia and took a median of 508 minutes (range 425-625). Median intensive care stay was 3 days (range 2-4), while hospital stay was 8 days (range 7-21) days. There were no deaths in-hospital or within 30 days. Complications were minor and self-limiting; there were no instances of renal failure. At a median follow-up of 29 months (range 14-38), no EVAR-related secondary interventions were required. CONCLUSION: Concomitant EVAR and cardiac surgery delivered by a multidisciplinary team is feasible, appears safe, and eliminates the risk associated with staged operations. Improved patient satisfaction and efficient use of resources are potential advantages.

Three strikes--don't die of a broken heart.

There are multiple layers of complexity in prevention of vehicle related blunt traumatic aortic rupture (BTAR), many of which are enshrined within government policy and car design. We present a 'layers of protection analysis' (LOPA) based loosely on original work by Professor John Doyle, which describes these attempts to 'design out' the risk of BTAR following a vehicle collision. We have modified this approach to include a physiological dimension suggesting that this may be a factor in susceptibility to aortic injury following trauma. Understanding processes involved in BTAR following vehicle collisions is key to designing preventative processes.

Blunt trauma and acute aortic syndrome: a three-layer finite-element model of the aortic wall.

OBJECTIVE: The exact process by which blunt trauma to the aorta produces a typical characteristic lesion set of primary, transverse, intimal injury remains unknown. The likely cause is a combination of intraluminal hypertension and mechanical deformation. We set about creating a three-layer finite-element model of the aorta. We hypothesised that deformation of the aorta through tension, torsion and bending would have differential effects on the constitutive layers of the aorta and this differential stress strain pattern would help to explain the mechanism of this injury. METHODS: A finite-element model of the aorta was created with three distinct layers representing tunica intima, media and adventitia. A rubble-like material model in the commercial dynamic finite-element package LS-DYNA was adopted. Numerical methods for considering the interaction between aortic tissue (solid) and blood (fluid) were defined using arbitrary Lagrangian Eulerian methods. Simulations of mechanical deformation including tension, torsion and bending were applied with loading set at 1m/s and intraluminal blood pressure rising from 86.6mmHg to 146mmHg. The simulations were run until material failure. The role of blood within these simulations was explored. RESULT: Our initial simulations confirmed the functionality of the three-layer finite-element model of the aorta with behaviour as expected from previously published experimentation. The addition of mechanical loading through torsion, tension and bending resulted in failure of the aorta at significantly lower mean blood pressures than without. Temporal and spatial aspects of failure were distinct for each method of loading. Bending resulted in rapid primary adventitial failure while tension and torsion resulted in a relatively delayed primary intimal failure. Blood flow altered the stress strain characteristics within the model. CONCLUSIONS: This work confirms the feasibility of using a three-layer FE model of the aorta. Our data suggest that the relative contribution of intraluminal hypertension to BTAR is lower in the presence of complex loading by tension, torsion and bending. In addition, failure of the aorta is load dependent with bending causing a relatively early primary adventitial failure, while tension and torsion result in a relatively delayed primary intimal failure.

Small vessel avulsion and acute aortic syndrome: a putative aetiology for initiation and propagation of blunt traumatic aortic injury at the isthmus.

Based on literature, clinical observation and the analysis of material properties of the aorta, we hypothesize that the aortic isthmus is intrinsically susceptible to blunt trauma because it has a higher density of tributary vessels than other elements of the aortic tree, the avulsion of which during trauma, is a contributory factor in the development of an acute aortic syndrome resulting from intra-mural haematoma, localized dissection and ultimately rupture. This hypothesis provides putative explanations for several aspects of the injury profile including: localized peri-isthmus injuries, inside out injury profiles and the concept of initiation versus propagation of blunt traumatic aortic injury.

Survival after esophageal resection for carcinoma: the importance of the histologic cell type.

BACKGROUND: The significance of tumor cell type on survival after esophageal resection for carcinoma is uncertain. We reviewed our experience in order to compare the outcome in the two main histologic groups. METHODS: Between January 1987 and April 2000, 621 patients underwent esophagectomy with curative intention for squamous cell carcinoma or adenocarcinoma. The postoperative outcomes of patients with adenocarcinoma and squamous cell carcinoma were compared. RESULTS: Of the cohort, 424 patients had adenocarcinoma (group A) and 197 had squamous cell carcinoma (group B). The commonest approach in group A was a left thoracotomy (67%), while in group B, it was an Ivor Lewis resection (55%) (p < 0.0001). Operative mortality was 3.5% for group A and 8.1% for group B (p = 0.03). Cardiorespiratory complication rate was similar, but anastomotic leaks occurred more frequently in group B (4.2% vs 8.6%, p = 0.04). Patients in group B tended to have earlier pathologic tumor, node, metastasis (pTNM) stage (p = 0.06). Overall, survival was significantly better for group B (p = 0.003). Group B had a significantly better survival than group A in lymph node (LN) negative status (p = 0.01), and a relatively improved survival in LN positive status (p = 0.35). On multivariate analysis, squamous cell subtype (p = 0.034), pTNM stage (p = 0.005), LN status (p = 0.008), and completeness of resection (p = 0.028) were significant predictors of survival. CONCLUSIONS: After esophagectomy, patients with squamous cell carcinoma have a poorer perioperative outcome as compared with those with adenocarcinoma. However, in the longer term, squamous cell type appears to confer a significant survival advantage.

Anticipatory Valsalva-type response as a contributory factor in low impact blunt traumatic aortic rupture.

Despite a range of trauma scenarios, fatal blunt injury to the chest commonly results from rupture of the aorta at the isthmus. The aetiology whereby blunt traumatic aortic rupture predictably occurs at the isthmus remains uncertain, and although a number of theoretical mechanisms have been proposed, no direct evidence exists supporting any one process. In addition, it is uncertain why some individuals who are exposed to relatively minor blunt trauma, sustain this injury. We have previously developed a finite element model in an attempt to simulate the large number of interdependent variables in this complex cardiopulmonary dynamic. This has led us to the conclusion that the physiological state at the moment of impact is important and that there may be a point of susceptibility to low impact blunt traumatic rupture in the cardiopulmonary dynamic. This manuscript suggests and develops an hypothesis based on the putative contribution of an anticipatory Valsalva-type response at the moment of impact and discusses possible mechanisms on how this might contribute to low impact blunt traumatic aortic rupture in individuals who sustain relatively minor trauma.

Functional compartmentation of glycogen phosphorylase with creatine kinase and Ca2+ ATPase in skeletal muscle.

This manuscript discusses aspects of functional compartmentation in the regulation of metabolism. The functional consequences of enzymes coupling between creatine kinase, glycogen phosphorylase and sarcoplasmic reticular Ca2+ ATPase is examined. It is proposed that the coupling of creatine kinase and glycogen phosphorylase classifies as a novel class of diazyme complex with an important regulatory role in the inhibition of glycogenolysis at rest. In addition it is suggested that creatine kinase, glycogen phosphorylase and the sarcoplasmic reticular Ca2+ ATPase may couple to form a three-enzyme complex. From a consideration of the structure and chemical catalysis of the putative three-enzyme complex, a novel net reaction for glycogenolysis in the vicinity of the sarcoplasmic reticulum is suggested (Phosphocreatine+Glycogen+H(+)Creatine+Glycogen(n)(-1)+Glucose-1-Phosphate). The three-enzyme complex may also have an important role in inhibiting glycogenolysis at rest as well as improving the efficiency of high-energy phosphate transfer.

Redo antireflux surgery--the importance of a tailored approach.

OBJECTIVE: Although several studies have examined early outcome following redo antireflux surgery, there is little data on the long-term efficacy of these procedures. We reviewed our experience of these operations in order to assess the long-term results which can be achieved by choosing redo antireflux procedures based on the results obtained from pre-operative oesophageal function testing. METHODS: The case notes of 26 patients who underwent a repeat antireflux procedure between 1981 and 2000 were reviewed. Clinical history, examination, endoscopy, pH studies, oesophageal manometry and video barium contrast studies were performed on all patients prior to re-operation. In all cases, a standardised pre-formulated algorithm, based on the results of the pre-operative oesophageal function tests, was used to determine the choice of surgical procedure. Post-operatively, patients were classified into three groups: Group A (those with no symptoms), Group B (symptoms controlled by medication) and Group C (symptoms refractory to medical treatment). Patients in Groups B and C underwent repeat oesophageal function studies. RESULTS: In all cases, the indication for re-operation was gastro-oesophageal reflux symptoms refractory to medical treatment. Twenty-one patients (81%) underwent a left thoracotomy, of whom 11 patients (42%) underwent a gastroplasty. The mean follow-up period was 8.27 years (range 1.5-19.8 years), after which 14 patients (54%) were classified as Group A; 10 patients (38%) as Group B; and 2 patients (8%) as Group C. Within Groups B and C, manometry showed that re-operation had increased basal lower oesophageal sphincter pressure (4.6 vs 12.7 mmHg, pre- vs post-operative P=0.03), and in all, but one case pH studies showed no evidence of recurrent acid reflux. CONCLUSIONS: Redo antireflux surgery can provide complete symptomatic relief in approximately 50% of patients and symptomatic improvement over 90% of patients. We advocate a tailored approach in the selection of re-operative procedures based on the results of pre-operative oesophageal function testing.

Histological determinants of survival in completely resected T1-2N1M0 nonsmall cell cancer of the lung.

BACKGROUND: The histologic determinants of survival after surgical resection of stage II nonsmall cell lung cancer are poorly understood. We analyzed the prognostic significance of a number of histologic features after complete resection of T1-2N1M0 nonsmall cell cancer of the lung. METHODS: The case notes and histology of all patients who underwent a potentially curative surgical resection for T1-2N1M0 nonsmall cell carcinoma of the lung between 1991 and 1997 were reviewed retrospectively. The following histologic factors were recorded: histologic type of tumor; number of nodes with metastatic deposits together with their nodal station; the presence of vascular invasion, visceral pleural involvement, and cellular necrosis; and grade of tumor. The results from 98 patients were analyzed. Univariate and multivariate analyses were performed to identify prognostic factors. RESULTS: Univariate analysis showed that only three factors had a statistically significant correlation with a poor prognosis: vascular invasion (p = 0.002), nonsquamous histology (p = 0.005), and visceral pleural involvement (p = 0.002). Multivariate analysis revealed that all three factors were significant independent adverse prognostic indicators. CONCLUSIONS: Visceral pleural involvement, nonsquamous histology, and vascular invasion are all significant adverse prognostic factors after surgical resection of T1-2N1M0 nonsmall cell cancer of the lung. These findings conflict with previously published reports, and we advocate a prospective, large-scale study in order to clarify the prognostic significance of histologic characteristics in stage II disease.