Heritable thoracic aortic disease: a literature review on genetic aortopathies and current surgical management

Heritable thoracic aortic disease puts patients at risk for aortic aneurysms, rupture, and dissections. The diagnosis and management of this heterogenous patient population continues to evolve. Last year, the American Heart Association/American College of Cardiology Joint Committee published diagnosis and management guidelines for aortic disease, which included those with genetic aortopathies. Additionally, evolving research studying the implications of underlying genetic aberrations with new genetic testing continues to become available. In this review, we evaluate the current literature surrounding the diagnosis and management of heritable thoracic aortic disease, as well as novel therapeutic approaches and future directions of research.

Computational fluid dynamics simulate optimal design of segmental arteries reattachment: Influence of blood flow stagnation

Objectives

This study aimed to simulate blood flow stagnation using computational fluid dynamics and to clarify the optimal design of segmental artery reattachment for thoracoabdominal aortic repair.

Methods

Blood flow stagnation, defined by low-velocity volume or area of the segmental artery, was simulated by a 3-dimensional model emulating the systolic phase. Four groups were evaluated: direct anastomosis, graft interposition, loop-graft, and end graft. Based on contemporary clinical studies, direct anastomosis can provide a superior patency rate than other reattachment methods. We hypothesized that stagnation of the blood flow is negatively associated with patency rates. Over time, velocity changes were evaluated.

Results

The direct anastomosis method led to the least blood flow stagnation, whilst the end-graft reattachment method resulted in worse blood flow stagnation. The loop-graft method was comparatively during late systole, which was also influenced by configuration of the side branch. Graft interposition using 20 mm showed a low-velocity area in the distal part of the side graft. When comparing length and diameter of an interposed graft, shorter and smaller branches resulted in less blood flow stagnation.

Conclusions

In our simulation, direct anastomosis of the segmental artery resulted in the most efficient design in terms of blood flow stagnation. A shorter (<20 mm) and smaller (<10 mm) branch should be used for graft interposition. Loop-graft is an attractive alternative to direct anastomosis; however, its blood flow pattern can be influenced.

Direct and indirect activation of the adenosine triphosphate-sensitive potassium channel to induce spinal cord ischemic metabolic tolerance

OBJECTIVES

The mitochondrial adenosine triphosphate-sensitive potassium channel is central to pharmacologically induced tolerance to spinal cord injury. We hypothesized that both direct and nitric oxide-dependent indirect activation of the adenosine triphosphate-sensitive potassium channel contribute to the induction of ischemic metabolic tolerance.

METHODS

Spinal cord injury was induced in adult male C57BL/6 mice through 7 minutes of thoracic aortic crossclamping. Pretreatment consisted of intraperitoneal injection 3 consecutive days before injury. Experimental groups were sham (no pretreatment or ischemia, n = 10), spinal cord injury control (pretreatment with normal saline, n = 27), Nicorandil 1.0 mg/kg (direct and indirect adenosine triphosphate-sensitive potassium channel opener, n = 20), Nicorandil 1 mg/kg + carboxy-PTIO 1 mg/kg (nitric oxide scavenger, n = 21), carboxy-PTIO (n = 12), diazoxide 5 mg/kg (selective direct adenosine triphosphate-sensitive potassium channel opener, n = 25), and DZ 5 mg/kg+ carboxy-PTIO 1 mg/kg, carboxy-PTIO (n = 23). Limb motor function was assessed using the Basso Mouse Score (0-9) at 12-hour intervals for 48 hours after ischemia.

RESULTS

Motor function was significantly preserved at all time points after ischemia in the Nicorandil pretreatment group compared with ischemic control. The addition of carboxy-PTIO partially attenuated Nicorandil's motor-preserving effect. Motor function in the Nicorandil + carboxy-PTIO group was significantly preserved compared with the spinal cord injury control group (P < .001), but worse than in the Nicorandil group (P = .078). Motor preservation in the diazoxide group was similar to the Nicorandil + carboxy-PTIO group. There was no significant difference between the diazoxide and diazoxide + carboxy-PTIO groups.

CONCLUSIONS

Both direct and nitric oxide-dependent indirect activation of the mitochondrial adenosine triphosphate-sensitive potassium channel play an important role in pharmacologically induced motor function preservation.

The Fate of Down-stream Aorta after Total Arch Replacement

OBJECTIVES

The aim of this study was to evaluate the fate of down-stream aorta following total arch replacement.

METHODS

Between October 1999 and March 2018, 740 patients underwent total arch replacement. After excluding connective tissue disease, previous descending or thoracoabdominal aortic surgery, patients without adequate preoperative images, or operative mortality, late outcomes consisting of additional surgery for distal dilation and distal aortic events were evaluated in 623 survivors (240 aortic dissections, including 139 patients with acute dissection and 383 with non-dissection aneurysm). The mean follow-up was 5.0 ± 4.0 years.

RESULTS

The mean preoperative maximum diameter of descending aorta was 36.9 ± 8.0 mm. Elephant trunk was inserted in 232 patients, including 183 patients with aortic dissection. Freedom from additional surgery for distal dilation was 88.5% at 5 years and 80.2% at 10 years. Freedom from distal aortic events was 81.9% at 5 years and 70.5% at 10 years. Multivariable regression analysis demonstrated that a preoperative diameter of descending aorta was a significant risk factor for unfavorable distal aortic events. Computed tomography evaluation demonstrated significant increase in descending aortic diameter over time (p < 0.001). Positive aortic remodeling was observed in the proximal descending (p < 0.001) to mid descending (p < 0.001) aorta exclusively in patients with acute aortic dissection.

CONCLUSIONS

The descending aortic diameter increased significantly after total arch replacement, particularly in distal descending aorta. Preoperative descending aortic diameter portended a significant risk for unfavorable distal aortic events.

The Effect of Ascending Aortic Repair on Left Ventricular Remodeling

Left ventricular (LV) hypertrophy is common in patients with thoracic aortic diseases and is associated with increased long-term mortality. Thoracic aortic aneurysms are reported to increase LV afterload because of kinetic energy loss within the aneurysm sac, which may improve after surgical repair. However, LV afterload may also increase because of the stiffness of prosthetics used for aortic repair. We sought to investigate the long-term effect of surgical aortic repair with prostheses on postsurgical LV mass. We reviewed patients who underwent ascending aortic replacement with a prosthesis at our institution from January 2008 to December 2018. We calculated the LV mass index based on pre- and postoperative echocardiogram measurements. The primary outcome was the change in LV mass index 6 months after aortic repair. Patients aged <18 years and those who had concomitant cardiac operations, severe aortic valve disease, or who had no echocardiographic data were excluded. Of 1,008 patients who underwent ascending aortic replacement, 134 (51 with acute aortic dissections) were included. The median baseline and follow-up LV mass index were 107 (90 to 135) g/m² and 101 (83 to 123) g/m², respectively. Overall, there was a significant reduction of LV mass index over time (p = 0.03). LV mass index decreased in 77 patients (59%). Presentation due to acute aortic dissection (p = 0.03) and baseline LV mass index (p <0.001) were significant predictors of LV mass reduction. In conclusion, LV mass index may significantly decrease over time after the aortic repair, but the course is highly variable. The largest decrease occurred in patients who presented because of aortic dissections rather than for elective repair of aneurysms.

Reoperative Aortic Valve Replacement After Bio-Bentall using a Double Sewing Ring Technique

We report an 89-year-old hemodialysis patient with a structural valve deterioration following a Bentall-de Bono operation with a tissue valve using the double sewing ring technique. The bioprosthesis was extracted easily, and the aortic valve replacement was performed without any complications in a high-risk patient. This procedure may be feasible given the prospects of reoperation.

Repair of Insufficient Aortic Valve and Single Coronary Artery with Intramural Course

We report about a patient with severe bicuspid aortic valve insufficiency and a single coronary artery with an intramural course. Aortic valve repair with double plication and coronary translocation was satisfactory.

Direct Innominate Artery Cannulation versus Side Graft for Selective Antegrade Cerebral Perfusion during Aortic Hemiarch Replacement

Background  Selective antegrade cerebral perfusion (SACP) has become our preferred method for cerebral protection during open arch cases. While the initial approach involved sewing a graft to the innominate artery as the arterial cannulation site, our access strategy has since evolved to central aortic cannulation with use of a percutaneous cannula in the innominate for SACP. We hypothesized that SACP delivered via direct innominate cannulation using a 12- or 14-Fr cannula results in equivalent outcomes to cases utilizing a side graft.

Methods  This was a single-center, retrospective analysis of 211 adult patients who underwent elective hemiarch replacement using hypothermic circulatory arrest with SACP via the innominate artery between 2012 and 2020. Urgent and emergent cases were excluded.

Results  A side graft sutured to the innominate was utilized in 81% ( n  = 171) of patients, while direct innominate artery cannulation was performed in 19% ( n  = 40) of patients. Baseline patient characteristics were similar between groups aside from a higher baseline creatinine in the direct cannulation group (1.3 vs. 0.9, p  = 0.032). Patients undergoing direct cannulation demonstrated shorter cardiopulmonary bypass time (132.7 vs. 154.9 minutes, p  = 0.020) and shorter circulatory arrest time (8.1 vs. 10.9 minutes, p  = 0.004). Nadir bladder temperature did not significantly differ between groups (27.2°C for side graft vs. 27.6°C for direct cannulation, p  = 0.088). There were no significant differences in postoperative outcomes.

Conclusion  Direct cannulation of the innominate artery with a 12- or 14-Fr cannula for SACP during hemiarch replacement is a safe alternative to using a sutured side graft. While cardiopulmonary bypass and circulatory arrest times appear improved, this is likely attributable to accumulation of experience and proficiency in technique. However, direct innominate artery cannulation may facilitate quicker completion of these procedures by eliminating the time necessary to suture a graft to the innominate artery.

The mid-term outcome of interventricular septal hematoma after ventricular septal defect closure

We present the case report of a patient who developed interventricular septal hematoma as a complication during perimembranous ventricular septal defect closure. Although cardiopulmonary bypass was re-established and the hematoma was aspirated, postoperative echocardiography revealed that the hematoma reaccumulated in the interventricular septum. She suffered from low-cardiac-output syndrome for 1 week requiring a large amount of inotropic agents. Postoperative echocardiography revealed that the interventricular septal hematoma gradually disappeared. At 1 year follow-up, ^99mTc-tetrofosmin myocardial single-photon emission computed tomographic revealed myocardial ischemia in the inferior and septal walls. At 4 years follow-up, her cardiac function has gradually improved. She has no symptoms of heart failure with angiotensin-converting enzyme inhibitor and beta-blocker.

Aortic endograft sizing and endoleak, reintervention, and mortality following endovascular aneurysm repair

OBJECTIVE

Endograft sizing for endovascular abdominal aortic aneurysm repair (EVAR) is not consistent despite published instructions for use (IFU). We sought to identify factors associated with over/undersizing, determine sex influence on sizing, and examine sizing effects on endoleak, reintervention, and mortality by analyzing data obtained from the W.L. Gore & Associates Global Registry for Endovascular Aortic Treatment (GREAT).

METHODS

All patients enrolled in GREAT undergoing EVAR were included for analysis. Proximal/distal aortic landing zones were compared with device implanted to assess sizing as related to IFU. χ²/Fisher exact tests were used to evaluate associations between IFU sizing and demographics. Logistic regression modeling was used to identify predictors of outside IFU sizing. Cox proportional hazards regression analyzed the relationship between sizing and endoleak, device-related reinterventions, and all-cause/aortic mortality.

RESULTS

There were 3607 EVAR subjects enrolled in GREAT as of March 2020. Of them, 1896 (53%) were within IFU for sizing, 791 (22%) were oversized, 540 (15%) were undersized, and 380 (10%) had both over- and undersized components. Factors predictive of use outside of IFU included female sex (P = .001), non-white race (P = .0003), decreased proximal neck length (P < .061), or larger iliac diameters (P < .0001). Women were more likely than men to have proximal neck undersizing and iliac limb oversizing, and men were more likely to have iliac limb undersizing. On multivariate analysis, undersizing of the proximal graft was associated with endoleak (hazard ratio [HR], 1.8) and aortic (HR, 60.5) and all-cause (HR, 18.0) mortality. Undersizing of iliac limbs was associated with endoleak (HR, 1.5) and device-related reintervention (HR, 1.4). Iliac limb outside IFU sizing was associated with aortic (HR, 2.6) and all-cause (HR, 1.3) mortality. Proximal and distal oversizing was not associated with adverse outcomes. Female sex was associated with mortality on univariate but not multivariate analysis.

CONCLUSIONS

Women undergoing EVAR with GORE EXCLUDER abdominal aortic aneurysm Endoprosthesis (W.L. Gore & Associates Inc, Flagstaff, Ariz) are more likely to have proximal stent-graft undersizing and iliac limb oversizing, whereas men are more likely to have undersized iliac limbs. Proximal aortic graft undersizing is associated with endoleak and all-cause/aortic mortality, whereas undersizing of iliac limbs is associated with endoleak and device-related reintervention. Oversizing was not associated with adverse outcomes.

Optimizing Nicorandil for Spinal Cord Protection in a Murine Model of Complex Aortic Intervention

There are currently no clinically utilized pharmacological agents for the induction of metabolic tolerance to spinal cord ischemia-reperfusion injury in the setting of complex aortic intervention. Nicorandil, a nitric oxide donor and ATP-sensitive potassium (KATP) channel opener, has shown promise in neuroprotection. However, the optimized clinical application of the drug and its mechanism of neuroprotection remains unclear. We hypothesized that 3-days pretreatment would confer the most effective neuroprotection, mediated by mitochondrial KATP channel activation. Spinal cord injury was induced by 7 minutes of thoracic aortic cross-clamping in adult male C57BL/6 mice. Time course: mice received 0.1 mg/kg nicorandil for 10 min, 4 hours, and 3 consecutive days prior to ischemia compared with control. Dose challenge: mice received 3-days nicorandil pretreatment comparing 0.1 mg/kg, 1.0 mg/kg, 5.0 mg/kg, and saline administration. Mitochondrial KATP channel blocker 5-hydroxy-decanoate (5HD) was co-administered to elucidate mechanism. Limb motor function was evaluated, and viable anterior horn neurons quantified. Nicorandil pretreatment at 4 hours and 3 days before ischemia demonstrated significant motor function preservation; administration 10 minutes before ischemia showed no neuroprotection. All nicorandil doses showed significant motor function preservation. Three days administration of Nicorandil 1.0 mg/kg was most potent. Neuroprotection was completely abolished by 5HD co-administration. Histological analysis showed significant neuron preservation with nicorandil pretreatment, which was attenuated by 5HD co-administration. Three days administration of Nicorandil 1.0 mg/kg showed near-total motor function preservation in a murine spinal cord ischemia-reperfusion model, mediated by the mitochondrial KATP channel.

The fate of the downstream aorta after open aortic repair for acute DeBakey type I aortic dissection: total arch replacement with elephant trunk technique versus non-total arch replacement†

OBJECTIVES

The aim of this study was to evaluate the fate of the downstream aorta following open aortic repair for acute DeBakey type I aortic dissection comparing total arch replacement (TAR) with the elephant trunk (ET) technique versus non-total arch replacement (non-TAR).

METHODS

From October 1999 to December 2016, 267 patients underwent open repair for acute DeBakey type I aortic dissection. A tear-oriented strategy was mainly used to determine the extent of graft replacement. Hospital mortality was 10.0% (12/120 patients) in the TAR group and 17.0% (25/147 patients) in the non-TAR group (P = 0.070). Late outcomes were compared in 230 hospital survivors (TAR: n = 108 and non-TAR: n = 122). Mean follow-up was 6.5 ± 4.6 years. The aortic diameters were measured at 4 levels, across 6 time points using computed tomography.

RESULTS

Freedom from additional aortic surgery for distal dilation was significantly better in the TAR group than the non-TAR group (TAR: 97.5 ± 1.8% at 5 years and non-TAR: 88.2 ± 3.4% at 5 years, P = 0.045). Freedom from a distal aortic event was also significantly better in the TAR group compared with the non-TAR group (TAR: 97.2 ± 1.6% at 5 years and non-TAR: 80.7 ± 4.2% at 5 years, P = 0.013). In the non-TAR group, the aortic arch diameter significantly increased (P < 0.001). Significant aortic remodelling occurred at the proximal descending aorta in the TAR with ET group (P < 0.001).

CONCLUSIONS

The TAR with ET reduced the need for additional distal aortic repair compared to non-TAR. TAR with ET prevented unfavourable aortic growth in both the aortic arch and the proximal descending aorta.

Right Thoracoscopic Aberrant Right Subclavian Artery Division and Subclavian-Carotid Transposition

Video-assisted thoracoscopic surgical division of obstructive congenital vascular rings has been demonstrated to be a safe technique in the setting of right-sided or double aortic arch, requiring a left-sided thoracic approach. This report describes 2 cases of aberrant right subclavian artery division using right video-assisted thoracoscopic surgery and subclavian-carotid transposition. This approach is safe and feasible in the management of symptomatic aberrant right subclavian artery without the morbidity of a thoracotomy incision, although patients require ongoing surveillance.

Post-sternotomy deep wound infection following aortic surgery: wound care strategies to prevent prosthetic graft replacement†

OBJECTIVES

The aim of this study was to evaluate the early and long-term outcomes of our multidisciplinary strategy for treating deep sternal wound infection after aortic grafting, which consisted of debridement by a plastic surgeon, negative pressure wound therapy with continuous irrigation and chest wall reconstruction.

METHODS

We performed a retrospective analysis of 18 patients who had a deep sternal wound infection following aortic grafting through a median sternotomy between January 2009 and December 2017. All patients had organisms cultured from mediastinal tissue within 2 months from the initial aortic surgery. The prosthetic grafts were exposed in 15 patients during resternotomy. Our protocol involved repeat debridement and negative pressure wound therapy with continuous irrigation twice a week until the results of the culture were negative and chest wall reconstruction was complete.

RESULTS

The mean duration from primary aortic surgery to resternotomy was 23.7 ± 15.9 days. Except for 1 patient, 17 patients underwent chest wall reconstruction. The mean duration from resternotomy to chest wall reconstruction was 31.1 ± 28.0 days. The hospital mortality rate was 16.7% (3 patients), although no patients died of wound-related causes. The mean follow-up period was 2.9 ± 2.5 years. Overall survival was 69.6 ± 11.4% at 1 year and 54.2 ± 13.3% at 5 years. Freedom from reoperation for reinfection was 94.4 ± 5.4% at 5 years.

CONCLUSIONS

Our wound care strategy achieved acceptable early and late survival in patients who had deep sternal wound infection following aortic grafting. This strategy may benefit those who experience this devastating complication.

Comparison of early patency rate and long-term outcomes of various techniques for reconstruction of segmental arteries during thoracoabdominal aortic aneurysm repair

OBJECTIVES

This study aimed to analyse the early patency rate and long-term outcomes of reattached segmental intercostal arteries using graft interposition, single-cuff anastomosis or island reconstruction.

METHODS

We selected 172 consecutive patients who underwent open surgery for the thoracoabdominal aorta with reattachment of segmental arteries between October 1999 and March 2018. The early patency of segmental arteries was analysed using enhanced computed tomography. Segmental arteries were reconstructed using graft interposition (n = 111), single-cuff anastomosis (n = 38) or island reconstruction (n = 23).

RESULTS

The hospital mortality was 6.4%. Twenty patients developed spinal cord ischaemic injury (permanent, n = 12 or transient, n = 8). Spinal cord injury was found in 16, 3 and 1 patients in the graft interposition, single-cuff anastomosis and island reconstruction groups, respectively. Overall, 475 segmental arteries were reattached (mean number per patient 2.8 ± 1.3). The overall early patency rate was 63.4%. The patency rates in island reconstruction (91.2%) and single-cuff anastomosis (77.1%) were significantly better than that in graft interposition (54.0%; P < 0.01). However, 6 patients with island reconstruction of segmental arteries had an aneurysm formation at the intercostal artery reconstruction site, of whom 4 patients underwent reoperation during follow-up. None of the patients with graft interposition or single-cuff reattachment had a patch aneurysm in segmental arteries.

CONCLUSIONS

Island reconstruction and single-cuff anastomosis might offer better patency rates and prevent spinal cord ischaemic injury than graft interposition. Because some patients with island reconstruction required reoperation for patch aneurysms in segmental arteries, single-cuff anastomosis is preferable in terms of early- and long-term outcomes.

A successful report of mitral valve repair for parachute-like mitral valve in adult

A 65 year-old man was diagnosed with congestive heart failure secondary to severe mitral regurgitation resulting from a parachute-like asymmetrical mitral valve. We performed mitral annuloplasty and triangular resection of the thick tissue. The postoperative course was uneventful with no recurrence of mitral regurgitation.

Valve-Sparing Root Replacement in Elderly Patients With Annuloaortic Ectasia

BACKGROUND

We report early and midterm outcomes of elderly patients who underwent valve-sparing root replacement (VSRR) compared with younger patients and those with Bentall procedure.

METHODS

From October 1999 to October 2017, 73 patients greater than or equal to 65 years of age who underwent VSRR procedure were assigned as group S. Two hundred thirty-two VSRR patients who were between 15 and 64 years of age were assigned as group Y. Forty-five patients greater than or equal to 65 years of age who underwent Bentall procedure were assigned as group R. Preoperative grades of aortic regurgitation were 3.4 of 4 in group S, 3.1 of 4 in group Y, and 3.3 of 4 in group R (p = 0.07).

RESULTS

Hospital mortality was found in 1 (1.4%) patient in group S, 3 (6.7%) in group R, and 2 (0.9%) in group Y. Postoperative survival at 5 years was 88.5% in group S, 98.7% in group Y, and 82.4% in group R (p < 0.01). Freedom from more than mild aortic regurgitation at 5 years was 81.0% in group S and 85.4% in group Y. Follow-up echocardiography disclosed an effective aortic valve orifice area of 1.76 cm² in group R, 2.40 cm² in group Y, and 2.41 cm² in group S (p < 0.01), and peak pressure gradient across the aortic valve was 17.7 mm Hg in group R, 13.6 mm Hg in group Y, and 10.8 mm Hg in group S (p < 0.01).

CONCLUSIONS

Similar early and late outcomes were achieved in elder VSRR patients compared with younger patients. A better postoperative valve performance was demonstrated in VSRR patients than patients undergoing valve-replacement.

Early and long-term outcomes of open surgery after thoracic endovascular aortic repair

OBJECTIVES

This study evaluated the early and long-term outcomes of open surgery after thoracic endovascular aortic repair.

METHODS

We conducted a retrospective review of 41 patients who underwent open surgery following thoracic endovascular aortic repair between October 1999 and July 2017. The mean interval from primary intervention to open surgery was 3.1 ± 3.7 years. Indications for open repair were endoleak in 14 patients, graft infection in 10 patients, false lumen dilatation in 9 patients, retrograde dissection in 5 patients, migration in 1 patient and additional aneurysm in 2 patients. Eight patients underwent emergent surgical conversions. The mean follow-up period was 4.2 ± 4.0 years.

RESULTS

Descending aortic replacement was performed in 15 patients; thoraco-abdominal aortic repair, in 14 patients; extensive arch to descending aortic replacement, in 5 patients; and total arch replacement, in 7 patients. Six (14.6%) patients died in the hospital. The 5-year survival rate was 73.7 ± 7.2%, and freedom from reintervention was 88.5 ± 6.4%.

CONCLUSIONS

Early outcomes of open surgical procedures after thoracic endovascular aortic repair were still suboptimal. However, hospital survivors had excellent long-term outcomes.

Anatomical variations of aortic arch vessels in Japanese patients with aortic arch disease

OBJECTIVES

The present study analyzed the prevalence of variations of the aortic arch branching in Japanese population, comparing patients with aortic arch disease with healthy controls.

METHODS

Between from October 1999 and December 2015, 815 Japanese patients with aortic arch disease defined as aortic arch aneurysm (diameter ≥ 45 mm) and aortic dissection (group A) underwent aortic arch surgery in our institution. As a control group, 1506 traumatic screened patients were enrolled (group C).

RESULTS

Aortic arch anomaly was diagnosed in 140 patients (17.2%) in the group A and in 222 patients (14.7%) in the group C (p = 0.125). Significant differences were found in the incidence of aberrant subclavian artery (A: 14 patients, 1.7%, vs. C: 8 patients, 0.5%, p = 0.006). Significantly more patients with aortic arch aneurysm in the group A had anomalies of the aortic arch compared with the group C (p = 0.009), including bovine aortic arch (p = 0.049) and aberrant subclavian artery (p < 0.001). In term of aneurysm location, bovine arch was detected in more patients with proximal arch aneurysm (15.7%, p = 0.043), whereas aberrant subclavian artery was in more patients with distal location (3.7%, p < 0.001). No difference was found in aortic arch anomaly in patients with acute or chronic dissection.

CONCLUSION

Aberrant subclavian artery was a significant maker of aortic arch disease in Japanese populations. Bovine arch was a risk maker of proximal arch aneurysm, and aberrant subclavian artery was a risk factor of distal arch aneurysm.

Successful hybrid treatment of a rare case of blunt traumatic rupture of the left atrial basal appendage and aortic arch

Despite advances in emergency care and the emergent transportation system, cardiac and aortic ruptures after blunt trauma are associated with high mortality and morbidity. We present a rare case of a 70-year-old man with a ruptured left atrial basal appendage and distal aortic arch after sustaining blunt trauma to the chest during a motor vehicle accident. The patient was transported to our hospital in a state of shock and taken directly to the operating room. Hybrid treatment was performed, including surgical repair of the left atrium under cardiopulmonary bypass and thoracic endovascular aortic repair, was performed. The patient fully recovered without any complications.

A case of type A acute aortic dissection with a common carotid trunk

We present a rare case of common carotid artery with acute type A aortic dissection. A 72-year-old woman underwent emergent aortic arch repair using Antegrade selective cerebral protection. Bottom-tapped cannulae were inserted into three orifices of arch vessels, however, regional cerebral oxygen saturation decreased after rewarming. We found that arch branches were in order from front to back, right subclavian artery, common carotid trunk, and left subcravian artery. The patient complicated stroke in the right middle cerebral artery.

Direct perfusion of the carotid artery in patients with brain malperfusion secondary to acute aortic dissection

OBJECTIVE

Presenting our experience of direct perfusion of the carotid artery in patients with brain malperfusion secondary to acute aortic dissection.

PATIENTS

Among 381 patients who underwent aortic repair for acute type A aortic dissection from October 1999 to August 2017, brain malperfusion was recognized in 50 patients. Nine patients had direct perfusion of the right carotid artery in patients with brain malperfusion secondary to acute aortic dissection. Age at surgery was 65.7 ± 13.5 years and three patients were male. Preoperative consciousness level was alert in one patients, drowsy in six, and coma in two. Five patients had preoperative hemiplegia. All patients showed a blood pressure difference between the upper extremities and eight patients showed more than 15% difference of rSO₂. Seven patients had a temporary external active shunt from the femoral artery to the right common carotid artery preoperatively. Two patients had direct perfusion to the right common carotid artery during cardiopulmonary bypass or in the intensive care unit after surgery because of a sudden decrease of rSO₂ and cessation of carotid artery flow. Antegrade cerebral perfusion was used in all patients. Total arch replacement was performed in six patients and hemiarch in three.

RESULTS

The hospital mortality was 33% (3 patients). Causes of death were huge hemispheric brain infarction or anoxic brain damage in two patients and myocardial infarction in one. The postoperative neurological outcome was alert in four, hemiplegia in two, and coma in three, but five patients showed some improvement of neurological signs.

CONCLUSION

Aggressive direct reperfusion of the carotid artery before the aortic repair may reduce neurological complications in patients with preoperative brain malperfusion secondary to acute aortic dissection.

The Vital Role of Pathology in Improving Reproducibility and Translational Relevance of Aging Studies in Rodents

Pathology is a discipline of medicine that adds great benefit to aging studies of rodents by integrating in vivo, biochemical, and molecular data. It is not possible to diagnose systemic illness, comorbidities, and proximate causes of death in aging studies without the morphologic context provided by histopathology. To date, many rodent aging studies do not utilize end points supported by systematic necropsy and histopathology, which leaves studies incomplete, contradictory, and difficult to interpret. As in traditional toxicity studies, if the effect of a drug, dietary treatment, or altered gene expression on aging is to be studied, systematic pathology analysis must be included to determine the causes of age-related illness, moribundity, and death. In this Commentary, the authors discuss the factors that should be considered in the design of aging studies in mice, with the inclusion of robust pathology practices modified after those developed by toxicologic and discovery research pathologists. Investigators in the field of aging must consider the use of histopathology in their rodent aging studies in this era of integrative and preclinical geriatric science (geroscience).

Spontaneous hepatocellular carcinoma is reduced in transgenic mice overexpressing human O6- methylguanine-DNA methyltransferase

O(6)-methylguanine (O(6)mG) is a potent mutagenic and procarcinogenic DNA lesion. Organisms have evolved with a DNA repair mechanism that largely ameliorates the deleterious effects of O(6)mG through a direct reversal mechanism by a protein termed O(6)-methylguanine-DNA methyltransferase (MGMT). However, the contribution of O(6)mG to carcinogenesis, in the absence of known exposure to agents that produce it, has not been defined. Nontransgenic C3HeB male mice have a high frequency of spontaneous liver tumors. Transgenic CeHeB/FeJ mice expressing human MGMT (hMGMT) were generated that had elevated hepatic MGMT activity. The spontaneous development of hepatocellular carcinoma was significantly reduced in those mice expressing hMGMT compared with nontransgenic C3HeB/FeJ male mice. No differences were detected in spontaneous mutant frequencies in lacI transgenes in mice carrying hMGMT compared with that without hMGMT but the proportion of GC to AT transition mutations was lower in the transgenic mice carrying hMGMT as well as lacI. Tumors that arose in C3HeB/FeJ transgenic mice were largely deficient in hMGMT protein as determined by immunohistochemistry with a monoclonal antibody directed against hMGMT. Together these data indicate that spontaneous O(6)mG lesions induced hepatocellular carcinogenesis in C3HeB/FeJ male mice. These transgenic mice represent a rare example of reduced spontaneous carcinogenesis.

Gene expression of cyclooxygenase in the aging heart

Cyclooxygenase (COX) is the key rate-limiting enzyme in the prostaglandin synthetic pathway. Two isoforms of COX have been identified: a constitutive COX-1 and an inducible COX-2, which is activated in response to various stimuli. We investigated the changes of COX-1 and COX-2 in rat heart during aging. We measured the age-related changes in the mRNA and protein levels of COX by using reverse-transcription polymerase chain reaction and Western blotting, respectively. COX-2 mRNA and protein levels increased with age, whereas those of COX-1 showed no change. The COX activity determined by prostaglandin E(2) production increased with age. Because the COX-catalyzed arachidonate cascade is an important source of reactive oxygen species (ROS) generation, changes in ROS generation and lipid peroxidation were also assessed. The amount of ROS generated by the COX pathway increased with age, as did the total ROS generation and lipid peroxidation. These results show that COX-2 activity increases with age, partially because of elevated transcriptional expression and protein content, and they suggest that increased COX-2 can play a role in oxidative alterations in the aged heart.

Health span and life span in transgenic mice with modulated DNA repair

One way to better understand the contribution of DNA repair, DNA damage, and mutagenesis in aging would be to enhance DNA repair activity, lower DNA damage, and lower mutagenesis. Because the repair protein O6-methylguanine-DNA methyltransferase (MGMT) acts alone and stoichiometrically, the human MGMT (hMGMT) cDNA was selected to test the feasibility of enhancing DNA repair activity in transgenic mice. MGMT activity is largely responsible for ameliorating the deleterious effects of O6-methylguanine (O6mG) lesions in DNA in a direct reversal mechanism. A transgene was constructed consisting of a portion of the human transferrin (TF) promoter and hMGMT cDNA such that hMGMT is expressed in transgenic mouse brain and liver. Expression of hMGMT was associated with a significant reduction in the occurrence of an age-related hepatocellular carcinoma in male mice at 15 months of age. Longitudinal and cross-sectional studies were initiated to determine whether the reduced incidence of hepatocellular carcinoma would impact median or maximum life span. The cross-sectional study performed on 15-month-old male animals confirmed the reduced occurrence of spontaneous hepatocellular carcinoma. At 30 months of age, however, the occurrence of hepatocellular carcinoma in at least one transgenic line was similar to that for nontransgenic animals. The longitudinal study is ongoing; however, at present no significant differences in life span have been detected. Tissues expressing the MGMT transgene also displayed greater resistance to alkylation-induced tumor formation. These results suggest that transgenes can be used to direct enhanced DNA repair gene expression and that enhanced expression can protect animals from certain spontaneous and induced tumors.

Modulation of renal xanthine oxidoreductase in aging: gene expression and reactive oxygen species generation

Xanthine oxidoreductase (XD: xanthine dehydrogenase + xanthine oxidase) is a complex enzyme that catalyzes oxidation of hypoxathine to xanthine, subsequently producing uric acid. The enzyme complex exists in separate but interconvertible forms, xanthine dehydrogenase (XDH) and xanthine oxidase (XOD). XOD is one of the major cellular sources of superoxide production and is well known as a causative factor in ischemia/reperfusion damage. At present, almost no information on the conversion status is available with respect to aging. In the present study, we investigated the effect of age on the XOD/XDH status and gene expression in the kidney. In addition, we assessed XOD-induced reactive oxygen species (ROS) using the dichlorofluoroscein (DCF) method. Our results show that XD activity gradually up to 18 months of age and then a slight decrease at 24 months of age. XDH activity showed increases up to 18 months of age, then decreased at 24 months of age. The conversion of XDH to XOD, assessed by changes in the ratios of XOD/(XOD+XDH), showed an age-related increase, which peaked at 24 months. Levels of XD protein and its mRNA paralleled to overall XD activity. ROS generation has tendency to increase with age. Our results suggest that the increased conversion of XDH to XOD observed with age may be an important contributing factor to the increased renal oxidative stress during aging.

Effects of aging and caloric restriction on IGF-I, IGF-I receptor, IGFBP-3 and IGFBP-4 gene expression in the rat stomach and colon

The purpose of this study was to determine the effects of aging and caloric restriction (CR) on insulin-like growth factor-I (IGF-I), IGF-I receptor (IGF-IR), IGF-binding protein-3 (IGFBP-3) and IGFBP-4 expression in the stomach and colon of male Fischer 344 rats. Stomach and colonic RNA were prepared from ad libitum (AL) fed or long-term CR rats. Stomach IGF-I, IGFBP-3 and IGFBP-4 mRNA levels increased significantly (P</=0.05), while colonic IGF-I mRNA levels were unchanged in aged AL rats. In aged CR rats, stomach IGFBP-3 mRNA levels decreased. Stomach and colonic IGF-IR mRNA levels declined with aging in AL and CR rats (P</=0.05). Colonic IGFBP-3 mRNA levels decreased significantly with aging in AL rats. There were no changes in colonic IGFBP-4 mRNA levels in aged AL or CR rats. Increased expression of stomach IGF-I, IGFBP-3 and IGFBP-4 in aged AL rats suggests that the stomach attempts to preserve IGF activity by increasing local expression of IGF-I and IGFBPs. Because the aging colon has a propensity to develop cancer, it may adapt to increased colonic IGF-I expression by reducing IGF-IR and IGFBP-3 expression. Additionally, CR lowers colonic IGF-I expression in aged rats (24 months) which may also be a protective adaptive mechanism.