Impacts of Telomeric Length, Chronic Hypoxia, Senescence, and Senescence-Associated Secretory Phenotype on the Development of Thoracic Aortic Aneurysm

Thoracic aortic aneurysm (TAA) is an age-related and life-threatening vascular disease. Telomere shortening is a predictor of age-related diseases, and its progression is associated with premature vascular disease. The aim of the present work was to investigate the impacts of chronic hypoxia and telomeric DNA damage on cellular homeostasis and vascular degeneration of TAA. We analyzed healthy and aortic aneurysm specimens (215 samples) for telomere length (TL), chronic DNA damage, and resulting changes in cellular homeostasis, focusing on senescence and apoptosis. Compared with healthy thoracic aorta (HTA), patients with tricuspid aortic valve (TAV) showed telomere shortening with increasing TAA size, in contrast to genetically predisposed bicuspid aortic valve (BAV). In addition, TL was associated with chronic hypoxia and telomeric DNA damage and with the induction of senescence-associated secretory phenotype (SASP). TAA-TAV specimens showed a significant difference in SASP-marker expression of IL-6, NF-κB, mTOR, and cell-cycle regulators (γH2AX, Rb, p53, p21), compared to HTA and TAA-BAV. Furthermore, we observed an increase in CD163⁺ macrophages and a correlation between hypoxic DNA damage and the number of aortic telocytes. We conclude that chronic hypoxia is associated with telomeric DNA damage and the induction of SASP in a diseased aortic wall, promising a new therapeutic target.

Early Mortality in Type A Acute Aortic Dissection: Insights From the International Registry of Acute Aortic Dissection

Importance

Early data revealed a mortality rate of 1% to 2% per hour for type A acute aortic dissection (TAAAD) during the initial 48 hours. Despite advances in diagnostic testing and treatment, this mortality rate continues to be cited because of a lack of contemporary data characterizing early mortality and the effect of timely surgery.

Objective

To examine early mortality rates for patients with TAAAD in the contemporary era.

Design, Setting, and Participants

This cohort study examined data for patients with TAAAD in the International Registry of Acute Aortic Dissection between 1996 and 2018. Patients were grouped according to the mode of their intended treatment, surgical or medical.

Exposure

Surgical treatment.

Main Outcomes and Measures

Mortality was assessed in the initial 48 hours after hospital arrival using Kaplan-Meier curves. In-hospital complications were also evaluated.

Results

A total of 5611 patients with TAAAD were identified based on intended treatment: 5131 (91.4%) in the surgical group (3442 [67.1%] male; mean [SD] age, 60.4 [14.1] years) and 480 (8.6%) in the medical group (480 [52.5%] male; mean [SD] age, 70.9 [14.7] years). Reasons for medical management included advanced age (n = 141), comorbidities (n = 281), and patient preference (n = 81). Over the first 48 hours, the mortality for all patients in the study was 5.8%. Among patients who were medically managed, mortality was 0.5% per hour (23.7% at 48 hours). For those whose intended treatment was surgical, 48-hour mortality was 4.4%. In the surgical group, 51 patients (1%) died before the operation.

Conclusions and Relevance

In this study, the overall mortality rate for TAAAD was 5.8% at 48 hours. For patients in the medical group, TAAAD had a mortality rate of 0.5% per hour (23.7% at 48 hours). However, among those in the surgical group, 48-hour mortality decreased to 4.4%.

Dynamic electrophysiological mechanism in patients with long-standing persistent atrial fibrillation

Background

Improved understanding of the mechanisms that sustain persistent and long-standing persistent atrial fibrillation (LSpAF) is essential for providing better ablation solutions. The findings of traditional catheter-based electrophysiological studies can be impacted by the sedation required for these procedures. This is not required in non-invasive body-surface mapping (ECGI). ECGI allows for multiple mappings in the same patient at different times. This would expose potential electrophysiological changes over time, such as the location and stability of extra-pulmonary vein drivers and activation patterns in sustained AF.

Materials and methods

In this electrophysiological study, 10 open-heart surgery candidates with LSpAF, without previous ablation procedures (6 male, median age 73 years), were mapped on two occasions with a median interval of 11 days (IQR: 8–19) between mappings. Bi-atrial epicardial activation sequences were acquired using ECGI (CardioInsight™, Minneapolis, MN, United States).

Results

Bi-atrial electrophysiological abnormalities were documented in all 20 mappings. Interestingly, the anatomic location of focal and rotor activities changed between the mappings in all patients [100% showed changes, 95%CI (69.2–100%), p < 0.001]. Neither AF driver type nor their number varied significantly between the mappings in any patient (median total number of focal activities 8 (IQR: 1–16) versus 6 (IQR: 2–12), p = 0.68; median total number of rotor activities 48 (IQR: 44–67) versus 55 (IQR: 44–61), p = 0.30). However, individual zones showed a high number of quantitative changes (increase/decrease) of driver activity. Most changes of focal activity were found in the left atrial appendage, the region of the left lower pulmonary vein and the right atrial appendage. Most changes in rotor activity were found also at the left lower pulmonary vein region, the upper half of the right atrium and the right atrial appendage.

Conclusion

This clinical study documented that driver location and activation patterns in patients with LSpAF changes constantly. Furthermore, bi-atrial pathophysiology was demonstrated, which underscores the importance of treating both atria in LSpAF and the significant role that arrhythmogenic drivers outside the pulmonary veins seem to have in maintaining this complex arrhythmia.

The Role of Telocytes and Telocyte-Derived Exosomes in the Development of Thoracic Aortic Aneurysm

A hallmark of thoracic aortic aneurysms (TAA) is the degenerative remodeling of aortic wall, which leads to progressive aortic dilatation and resulting in an increased risk for aortic dissection or rupture. Telocytes (TCs), a distinct type of interstitial cells described in many tissues and organs, were recently observed in the aortic wall, and studies showed the potential regulation of smooth muscle cell (SMC) homeostasis by TC-released shed vesicles. The purpose of the present work was to study the functions of TCs in medial degeneration of TAA. During aneurysmal formation an increase of aortic TCs was identified in human surgical specimens of TAA-patients, compared to healthy thoracic aortic (HTA)-tissue. We found the presence of epithelial progenitor cells in the adventitial layer, which showed increased infiltration in TAA samples. For functional analysis, HTA- and TAA-telocytes were isolated, characterized, and compared by their protein levels, mRNA- and miRNA-expression profiles. We detected TC and TC-released exosomes near SMCs. TAA-TC-exosomes showed a significant increase of the SMC-related dedifferentiation markers KLF-4-, VEGF-A-, and PDGF-A-protein levels, as well as miRNA-expression levels of miR-146a, miR-221 and miR-222. SMCs treated with TAA-TC-exosomes developed a dedifferentiation-phenotype. In conclusion, the study shows for the first time that TCs are involved in development of TAA and could play a crucial role in SMC phenotype switching by release of extracellular vesicles.

Type A Acute Aortic Dissection Presenting With Cerebrovascular Accident at Advanced Age

Our aim was to analyze outcomes of patients aged 70 years or above presenting with type A acute aortic dissection (TAAAD) and cerebrovascular accident (CVA). A retrospective analysis of the International Registry of Acute Aortic Dissection (IRAD) was conducted. Patients aged 70 years or above (n = 1449) were stratified according to presence or absence of CVA before surgery (CVA: n = 110, 7.6%). In-hospital outcomes and mortality up to 5 years were analyzed. Additionally, in-hospital outcomes of patients who received medical management were described. No patient presenting with CVA over the age of 87 years underwent surgery. The rates of in-hospital mortality and post-operative CVA were significantly higher in patients presenting with CVA (in-hospital mortality: 32.7% vs 21.7%, P = 0.008; post-operative CVA: 23.4% vs 8.3%, P < 0.001). Presence of CVA was independently associated with significantly increased in-hospital mortality (odds ratio 2.99, 95% confidence interval 1.35 - 6.60, P = 0.007). In survivors of the hospital stay, presenting CVA had no independent influence on mortality up to 5 years (hazard ratio 1.52, 95% confidence interval 0.99 - 2.31, P = 0.54). In medically managed patients, exceedingly high rates of in-hospital mortality (71.4%) and CVA (90.9%) were noted. Patients presenting with TAAAD and CVA at ≥ 70 years of age are at significantly increased risk of in-hospital mortality, although long-term mortality is not affected in hospital survivors. Medical management is associated with poor outcomes. We believe that surgical management should be offered after critical assessment of comorbidities.

Time of day does not influence outcomes in acute type A aortic dissection: Results from the IRAD

BACKGROUND

Type A acute aortic dissection (TAAAD) represents a surgical emergency requiring intervention regardless of time of day. Whether such a "evening effect" exists regarding outcomes for TAAAD has not been previously studied using a large registry data.

METHODS

Patients with TAAAD were identified from the International Registry of Acute Aortic Dissections (1996-2019). Outcomes were compared between patients undergoing operative repair during the daytime (D), defined as 8 am-5 pm, versus the evening (N), defined as 5 pm-8 am.

RESULTS

Four thousand one-hundrd and ninety-seven surgically treated patients with TAAAD were identified, with 1824 patients undergoing daytime surgery (43.5%) and 2373 patients undergoing evening surgery (56.5%). Daytime patients were more likely to have undergone prior cardiac surgery (13.2% vs. 9.5%; p < .001) and have had a prior aortic dissection (4.8% vs. 3.4%; p = .04). Evening patients were more likely to have been transferred from a referring hospital (70.8% vs. 75.0%; p = .003). Daytime patients were more likely to undergo aortic valve sparing root procedures (23.3% vs. 19.2%; p = .035); however, total arch replacement was performed with equal frequency (19.4% vs. 18.8%; p = .751). In-hospital mortality (D: 17.3% vs. N. 16.2%; p = .325) was similar between both groups. Subgroup analysis examining the effect of weekend presentation revealed no significant mortality difference.

CONCLUSIONS

A majority of TAAAD patients underwent surgical repair at night. There were higher rates of postoperative tamponade in evening patients; however, mortality was similar. The expertise of cardiac-dedicated operative and critical care teams regardless of time of day as well as training paradigms may explain similar mortality outcomes in this high risk population.

Insights From the International Registry of Acute Aortic Dissection: A 20-Year Experience of Collaborative Clinical Research

Acute aortic dissection (AAD) is a life-threatening condition associated with high morbidity and mortality rates, and it remains a challenge to diagnose and treat. The International Registry of Acute Aortic Dissection was established in 1996 with the mission to raise awareness of this condition and provide insights to guide diagnosis and treatment. Since then, >7300 cases have been included from >51 sites in 12 countries. Although presenting symptoms and physical findings have not changed significantly over this period, the use of computed tomography in the diagnosis has increased, and more patients are managed with interventional procedures: surgery in type A AAD and endovascular therapy in type B AAD; with these changes in care, there has been a significant decrease in overall in-hospital mortality in type A AAD but not in type B AAD. Herein, we summarized the key lessons learned from this international registry of patients with AAD over the past 20 years.

Thoracoabdominal Aortic Aneurysm Repair: Reducing Adverse Outcome with Left Heart Bypass, Selective Visceral Perfusion and Renal Protection

Objective: To report our experience with left heart bypass and selective visceral perfusion for prevention of permanent spinal cord injury and distal organ failure in patients undergoing thoracoabdominal aortic aneurysm repair.

Methods: From April 2001 to March 2002 seven patients were electively operated on with left heart bypass and selective perfusion of the visceral and renal organs at the University Clinic of Vienna, Austria. There were four males (57%) and two females (43%) with a mean age of 70 ± 6 years. Etiology of the aneurysm was a chronic dissection in one patient and athereosclerotic in the remaining five. Crawford classification was I in one patient (14%), II in five patients (86%) and III in one patient (14%). Existing comorbidities were hypertension in all seven patients, coronary artery disease in two patients (29%), chronic pulmonary obstructive disease in two patients (29%), and lung cancer resection and peripheral artery occlusive disease in one patient (14%) each. Two patients had a history of prior aortic aneurysm repair, namely elective repair of the ascending thoracic aorta 2 months before the thoracoabdominal aortic aneurysm repair, and replacement of the infrarenal aorta 12 years previously in another patient.

Results: All patients survived the operation and were discharged after a mean hospital stay of 25 ± 13 days. Adverse outcome occurred in three out of seven patients. One patient with Crawford classification 11 developed acute renal insufficiency, and two patients with class 11 and III showed signs of transient paraparesis, respectively. Mean intraoperative blood loss was 3315 ± 701 ml. On average, 6.7 ± 2.8 units of packed red cells, 10 units of fresh frozen plasma, and 1 unit of platelets were given during the operation. Intensive care unit stay ranged from 2 to 16 days.

Conclusions: The combined usage of left heart bypass, selective visceral perfusion, and renal protection can be recommended as a useful and effective technique in order to minimize adverse outcome in patients undergoing repair of the thoracoabdominal aorta.

The IRAD classification system for characterizing survival after aortic dissection

BACKGROUND

The classification of aortic dissection into acute (<14 days from symptom onset) versus chronic (≥14 days) is based on survival estimates of patients treated decades before modern diagnostic and treatment modalities were available. A new classification of aortic dissection in the current era may provide clinicians with a more precise method of characterizing the interaction of time, dissection location, and treatment type with survival.

METHODS

We developed separate Kaplan-Meier survival curves for Type A and Type B aortic dissection using data from the International Registry of Aortic Dissection (IRAD). Daily survival was stratified based on type of therapy provided: medical therapy alone (medical), nonsurgical intervention plus medical therapy (endovascular), and open surgery plus medical therapy (surgical). The log-rank statistic was used to compare the survival curves of each management type within Type A and Type B aortic dissection.

RESULTS

There were 1815 patients included, 67.3% male with mean age 62.0 ± 14.2 years. When survival curves were constructed, 4 distinct time periods were noted: hyperacute (symptom onset to 24 hours), acute (2-7 days), subacute (8-30 days), and chronic (>30 days). Overall survival was progressively lower through the 4 time periods.

CONCLUSIONS

This IRAD classification system can provide clinicians with a more robust method of characterizing survival after aortic dissection over time than previous methods. This system will be useful for treating patients, counseling patients and families, and studying new diagnostic and treatment methods.

Abstract 283: Diabetes and Dissection: An Analysis from the International Registry of Acute Aortic Dissection

Background: Studies have shown that diabetes is less prevalent in acute aortic dissection (AAD) or aortic aneurysm patients (pts) than it is in those with coronary artery disease or heart failure. While diabetes has been found to inhibit aortic aneurysm development in laboratory animals, little is known about its impact on AAD.

Methods: Of 3,662 pts enrolled in the International Registry of Acute Aortic Dissection, 248 (6.8%) were diabetic. Diabetic and non-diabetic pts with type A (TA) (n=2371, 6.2% diabetic) and type B (TB) (n=1291, 7.9% diabetic) AAD were compared in this study.

Results: Diabetic pts were on average older than non-diabetic for both TA (67.7 vs 61.4 years, p<0.001) and TB (67.8 vs 63.2 years, p<0.001). Pts with TA AAD and diabetes were more often managed medically (18.5%, 27/287 vs 11.7%, 260/2225, p=0.015), while TB diabetic pts were more likely to undergo endovascular procedures (29.4%, 30/102 vs 20.8%, 247/1189, p=0.045).

TA diabetics had more in-hospital myocardial infarction (12.9%, 18/139 vs 6.8% 143/2099, p=0.007). Both TA and TB diabetics had more acute renal failure in hospital (TA: 34.3%, 48/140 vs 24.4% 513/2105, p=0.009; TB: 27.7% 28/101 vs 16.8%, 188/1118, p =0.006). In-hospital mortality was similar between groups. TB diabetics had significantly higher follow-up mortality on Kaplan-Meier analysis (p=0.028).

Conclusion: Diabetes does not appear to impact treatment selection or in-hospital mortality for pts with AAD. However, it is important to note that diabetic pts demonstrate lower rates of follow-up survival, a trend that reaches significance in type B pts. The lower prevalence of diabetes among IRAD pts compared to other cardiovascular diseases suggests that diabetes may impact the development of AAD.

Abstract 264: Pulse Pressure and Type A Acute Aortic Dissection Outcomes: Insights from the International Registry of Acute Aortic Dissection

Background: Little is known about the relationship between Type A Acute Aortic Dissection (TAAAD) and pulse pressure (PP), defined as the difference between systolic and diastolic blood pressure. This study explores the association between PP and presentation, complications and outcomes of TAAAD patients.

Methods: PP at hospital presentation was used to divide 1,960 non-iatrogenic TAAAD patients into quartiles: narrowed (≤39 mmHg; n=430), normal (40-56 mmHg; n=554), mildly elevated (57-75 mmHg; n=490) and markedly elevated (≥76 mmHg; n=486). Variables relating to index presentation and in-hospital outcomes were analyzed.

Results: TAAAD patients (patients) in the narrowed PP quartiles were more frequently older and Caucasian while patients with markedly elevated PPs tended to be male and have a history of hypertension. Patients who demonstrated abdominal vessel involvement more commonly demonstrated elevated PPs whereas patients with narrowed PPs were more likely to have periaortic hematoma and/or pericardial effusion. Narrowed PPs were also correlated with higher incidences of hypotension, cardiac tamponade and mortality. TAAAD patients who were managed with endovascular and hybrid procedures and those with renal failure tended to have elevated PPs. No difference in aortic regurgitation at presentation was noted between groups.

Conclusions: TAAAD patients in the middle two PP quartiles had better in-hospital outcomes than patients in the outer quartiles. Patients with narrowed PPs experienced more cardiac complications, particularly cardiac tamponade, while those with elevated PPs were more likely to have abdominal aortic involvement. Presenting PP offers a clue to different manifestations of AAD that may facilitate initial triage and care.

Abstract 274: Follow-Up of Young Acute Aortic Dissection Patients: How They Differ from Older Patients

Background: Young patients (pts) with acute aortic dissection (AAD) have distinct risk factors and presenting symptoms compared to older pts, but whether these differences extend past discharge is relatively unknown.

Methods: Among pts presenting with AAD enrolled in the International Registry of Acute Aortic Dissection, pts <40 (N=280) were compared with pts ≥ 40 (N=3585). Chi-square analysis or Fischer’s Exact test were performed for categorical variables; age was compared using Student’s T-test. Kaplan-Meier curves were generated for freedom from adverse events rates 0-60 months following discharge. Mean follow-up was 28.6 months.

Results: Significant differences in demographics and history were noted between pts <40 and the older cohort. Young pts more commonly had type A AAD (71.8%, 201/280, v. 64.6%, 2317/ 3585, p<0.016), while type B AAD was more typical in older pts (p<0.016). On imaging studies, pts <40 were less likely to present with IMH (7.3%, 246/3355, v. 2.3%, 6/266, p=0.002), but were more likely to have a patent false lumen (77.9%, 141/181, v. 62.1%, 1425/2295, p<0.001). Surgical management was more common in young pts, for both AAD types. In-hospital complications or mortality did not differ between groups. Kaplan-Meier analysis demonstrated better long-term survival in young pts compared to those ≥ 40 (p=0.029). Kaplan-Meier analyses of freedom from adverse events at 5 years illustrated no difference in aortic growth between groups, but significantly more late interventions in younger pts (p=0.006).

Conclusions: Young pts show distinct differences in comparison to older pts, specifically regarding presentation, AAD type and management. Long-term survival and follow-up intervention rates are higher in young pts.

Midterm results after endovascular treatment of acute, complicated type B aortic dissection

BACKGROUND

The purpose of this study was to assess the efficacy and midterm results of endovascular treatment of acute, complicated type B aortic dissection.

METHODS

Between January 2001 and February 2010, 32 patients (7 women, 25 men) with acute, complicated type B aortic dissection (mean age, 56 years; range, 35 to 83 years), defined as either aortic rupture, malperfusion, intractable pain, or uncontrolled hypertension, underwent endovascular stent graft placement with either the Gore Excluder/TAG device (n = 11), Medtronic Talent/Valiant device (n = 16), Bolton Relay (n = 2), or a combination of these stents (n = 3). Follow-up was 94% complete and averaged 26 ± 23 months.

RESULTS

Technical feasibility and success with deployment proximal to the entry tear was 87%, requiring partial or total coverage of the left subclavian artery (LSA) in 9 patients (28%). Hospital mortality was 12% ± 11% (95% confidence limit) with 2 late deaths (17 and 98 months after implant). Causes of hospital death included rupture in 2, retrograde type A dissection in 1, and multiorgan failure in 1 patient. Three patients (11%) experienced new neurologic complications (2 paraparesis and 1 hemiparesis). Six patients with malperfusion required branch vessel stenting. Furthermore, 2 had an early type Ia endoleak. Actuarial survival at 1 and 5 years was 81% and 76%, respectively. Freedom from treatment failure at 1 and 5 years (including reintervention, aortic rupture, device-related complication, and aortic related death) was 78% and 61%, respectively.

CONCLUSIONS

Endovascular stent-graft placement in acute, complicated type B aortic dissection proves to be a promising alternative therapeutic treatment modality in this relatively difficult patient cohort. Refinements, especially in stent design and application, may further improve the prognosis of patients in this life-threatening situation.

Composite aortic root replacement using the classic or modified Cabrol coronary artery implantation technique

BACKGROUND

We report in this study our results with composite aortic root replacement (CVR) using the classic or modified Cabrol coronary implantation technique.

MATERIAL AND METHODS

From October 2001 to March 2005, 25 patients underwent aortic root replacement. In all cases, the indication for surgery was a degenerative aneurysm with a diameter of more than 6 cm. Seven patients had undergone a previous aortic operation on the ascending aorta. Mean age was 53+/-13 years and 22 patients were male. Mean Euroscore was 5.2+/-2.4. Aortic insufficiency was present in all patients. Two patients had Marfan syndrome.

RESULTS

The 30-day mortality was 0%. Two patients required profound hypothermic circulatory arrest. Mean aortic cross-clamp time was 91+/-24 minutes and the mean circulatory arrest time was 24+/-15 minutes. No patients developed a pseudoaneurysm after the operation.

CONCLUSION

We conclude that composite aortic root replacement with the classic or modified Cabrol technique results in a low operative mortality. However, it should be only used when a "button" technique is not feasible.

Preoperative antithrombin III activity predicts outcome after surgical repair of acute type A aortic dissection

BACKGROUND

Acute Stanford type A aortic dissection is associated with substantial perioperative morbidity and mortality. A sepsis-like state may lead to antithrombin (AT) III consumption and deficiency. The impact of preoperative AT III activity on outcome in patients undergoing emergency surgery is yet unknown.

METHODS

We measured preoperative AT III activity in 99 consecutive patients undergoing emergency aortic surgery for Stanford type A aortic dissection during a 4-year period in a retrospective study. Cardiovascular co-morbidities, risk factors and surgical data were recorded and patients were followed for 30-day mortality, and occurrence of multiple organ failure (MOF).

RESULTS

During the first 30 days, 15 patients (15%) died, and 8 patients (8%) had MOF. Median AT III levels (IQR) in 30-day non-survivors versus survivors were 64% (52-72) versus 90% (75-97) (p<0.001), and in patients with versus without MOF were 66% (52.3-77.3) versus 88% (72-96) (p=0.018), respectively. Adjusted odds ratios for 30-day mortality and MOF for AT III activity (per % increments) were 0.92 (p=0.007), and 0.96 (p=0.012), respectively, indicating a significant inverse relationship between AT III activity and outcome.

CONCLUSION

There is a strong inverse association between preoperative AT III activity and adverse outcome in patients undergoing surgical repair of acute Stanford type A aortic dissection. Larger studies are necessary to determine a cut-off value for AT III and to assess whether patients with low AT III levels benefit targeted therapeutic interventions.

Endovascular repair of the thoracic aorta necessitating anchoring of the stent graft across the arch vessels

OBJECTIVE

The purpose of the study was to determine technical and clinical results in endovascular repair of thoracic aortic diseases necessitating stent-graft anchoring across the arch vessels.

METHODS

The causes for endovascular treatment in 58 patients (aged 20 to 84 years) were aneurysms (n = 32), acute type A (n = 2) and type B dissections (n = 17), posttraumatic transections (n = 4), iatrogenic dissection (n = 1), and penetrating ulcers with an intramural hematoma (n = 2). Surgical revascularization of arch vessels was performed in 26 patients before stent-graft implantation. Intentional overstenting of the left subclavian artery resulted in complete occlusion in 8 and was partial in 24 patients.

RESULTS

The 30-day mortality rate was 3.4%. Overall, 19 major postprocedural complications occurred in 14 (24%) patients. Among patients with left subclavian artery occlusion, 2 patients had major (1 paraplegia, 1 critical arm ischemia), and 3 minor (2 temporary vertebrobasilary symptoms, 1 transient arm claudication) complications. Fourteen (25%) patients had an early endoleak, of whom 5 were treated successfully with a secondary endovascular procedure, 2 necessitated open surgical conversion, and 7 were treated conservatively, with spontaneous sealing of the endoleak in 3. In 53 (91%) in whom computed tomographic follow-up was longer than 3 months (mean, 30.1 months, range, 3 to 85), the aortic diameter along the stented segment decreased in 24, was stable in 19, and increased in 10 patients.

CONCLUSION

Fixation of the stent graft in the aortic arch can expand the applicability of endovascular repair. Intentional overstenting should be performed with caution to avoid ischemic problems after complete occlusion of left subclavian artery.

Conversion from cyclosporine to tacrolimus improves renal function and lipid profile after cardiac transplantation

BACKGROUND

Calcineurin inhibitors (CNIs) have become the cornerstone of immunosuppressive regimens following heart transplantation, but their use is associated with nephrotoxicity. The impact on renal function after conversion from cyclosporine (CsA) to tacrolimus (TAC) is reported.

PATIENTS AND METHODS

Fifteen patients (men age 42 +/- 11 years) after cardiac transplantation (HTX) were switched from CsA to TAC (mean time after HTX 21 +/- 6 months). There were 13 male and 2 female patients. Mean cholesterol and LDL level at the time of conversion were 217 +/- 65 ml/dl and and 136 +/- 51 mg/100 ml respectively. Indication for HTX was ischemic cardiomyopathy (CMP) in 8, congenital in 3 and dilatative CMP in the remaining 4 patients.

RESULTS

Mean tacrolimus level (microg/dl) at 1, 3, 6 and 12 months were 8.6 +/- 3.3, 8.6 +/- 1.4, 9.2 +/- 2.8 and 9.8 +/- 2.5 respectively. There was a statistically significant improvement in creatinine levels at 1, 3, 6 and 12 months after conversion from baseline 1.9 +/- 0.7 mg/dl to 1.4 +/- 0.5 mg/dl, 1.4 +/- 0.4 mg/dl, 1.3 +/- 0.4 mg/dl and 1.2 +/- 0.4 mg/dl, respectively (p < 0.05). Furthermore, TAC decreased cholesterol as well as LDL-levels during this one-year time frame.

CONCLUSION

This study shows that conversion from CsA to tacrolimus after orthotopic heart transplantation improves renal function.

A case of candida albicans mediastinitis after heart transplantation successfully treated with caspofungin

Reported here is a case of mediastinitis caused by candida albicans and Staphylococcus aureus following a heart transplantation that was successfully treated with caspofungin, antibiotics and mediastinal lavage. A review of the literature revealed that Candida albicans as a cause of mediastinitis has been rarely described. In the few existing reports, evolution was generally fatal, especially in immunocompromised patients, despite treatment with antifungal drugs and antibiotics.

Predictors of adverse outcome and transient neurological dysfunction following surgical treatment of acute type A dissections

Predictors of adverse outcome after replacement of the ascending aorta with resection of the intimal tear and open distal anastomosis were analyzed in 167 patients (109 male, median age 56). Median hypothermic circulatory arrest (HCA) time was 30 minutes (range 12 to 113). Eighty-six patients (pts) had surgery within 24 hours and 81 within 72 hours of symptom onset. Thirty-seven pts had only ascending aortic replacement, 128 had hemiarch repair, and in 2 the entire arch was replaced. The aortic valve was replaced in 37 pts, resuspended in 116, and untouched in 14. Either death or permanent neurological dysfunction was considered an adverse outcome (AO). AO occurred in 30.5% (51/167) of patients overall. Multivariate analysis revealed that the only significant (P<0.05) independent preoperative predictor of AO was hemodynamic instability (OR 6.0). Transient neurological dysfunction (TND) occurred in 19 of 116 patients (16.4%). Significant predictors of TND were increasing age >60 (OR 3.4 and 7.0 in the second and third tertile as compared with the lowest tertile) and coronary heart disease (OR 3.4). Cumulative survival of patients (median follow-up 34 months) was 55% at 1, 49% at 5, and 44% at 8 years, indicating an excessive in-hospital mortality, but excellent long term outcome. Surgical treatment of acute type A dissections is still associated with a high incidence of adverse outcome, but results in excellent long-term survival. Earlier diagnosis, before the development of cardiac tamponade and hemodynamic compromise, is critical to improve the operative salvage rate.

Effect of aneurysm on the tensile strength and biomechanical behavior of the ascending thoracic aorta

BACKGROUND

Rupture of an ascending thoracic aortic aneurysm (ATAA), which is associated with significant mortality, occurs when the mechanical forces acting on the aneurysm exceed the strength of the degenerated aortic wall. The purpose of this study was to evaluate changes in biomechanical properties of the aortic wall related to ATAA formation.

METHODS

Ascending thoracic aortic aneurysm tissue was obtained from surgery; control (nonaneurysmal) aorta was obtained from autopsy. Tissue strips with longitudinal (LONG) or circumferential (CIRC) orientation were stretched to failure. Maximum tissue stiffness and tensile strength were determined from plots of stress (normalized force) versus strain (normalized deformation). Student's t test was used for all comparisons.

RESULTS

Tensile strength of LONG (nATAA = 17, n(control) = 7) and CIRC (nATAA = 23, n(control) = 7) ATAA specimens were 29% and 34% less than that of control tissue, respectively (p < 0.05). Maximum tissue stiffness was 72% stiffer for LONG ATAA (p < 0.05) and 44% stiffer for CIRC ATAA (p = 0.06) than for control tissue, respectively.

CONCLUSIONS

The data suggest that ATAA formation is associated with stiffening and weakening of the aortic wall, which may potentiate aneurysm rupture.

Combined surgical and endovascular treatment of acute aortic dissection type A: preliminary results

BACKGROUND

The established treatment modality of acute Stanford type A dissection includes repair of the ascending aorta and various portions of the aortic arch, whereas the descending aorta is left untreated. We report a simultaneous approach of open repair of the ascending aorta with transluminal stent grafting of the descending aorta to minimize the consequences of an untreated descending aorta.

METHODS

From April 2001 to February 2002, 8 consecutive patients (3 women [37.5%] and 5 men [62.5%]) with a mean age of 55.7 years (range, 45 to 70 years) were intended to be treated with the combined method of surgical repair of the ascending aorta and transluminal stent grafting into the descending aorta during the period of deep hypothermic circulatory arrest. Circulatory arrest time ranged between 30 and 67 minutes (average, 38.8 minutes). Specially designed Talent stent grafts (32 to 40 mm in diameter, length 13 cm) were inserted under direct vision and deployed with the proximal end at the origin of the left subclavian artery.

RESULTS

Intraoperative stent graft placement was successful in 7 patients (87.5%). Because of severe kinking of the distal arch, stent insertion failed in 1 patient (12.5%). One patient with a history of preoperative stroke in the middle cerebral artery died because of intracerebral bleeding on postoperative day 2, resulting in an in-hospital mortality of 12.5%. Mean intensive care unit stay was 6.4 days (range, 2 to 21 days) and overall hospital stay was 18.2 days (range, 7 to 33 days). Completion computed tomographic scans revealed complete thrombosis of the false lumen in 2 patients and partial thrombosis in 4 patients. Follow-up was complete and ranged from 1 to 9 months (mean, 5.4 months).

CONCLUSIONS

This preliminary study shows that combined surgical and endovascular treatment of acute type A dissection is feasible, and at least partial thrombosis of the false lumen can be achieved, potentially minimizing the risk of further dilatation or rupture. Additionally, the stent graft expands the otherwise sickle-shaped true lumen, thereby ameliorating distal aortic perfusion. Long-term results are warranted to demonstrate the effectiveness of this new combined treatment modality.

Surgical treatment of acute type A dissection: is rupture a risk factor?

BACKGROUND

The purpose of this study was to evaluate the significance of aortic rupture on clinical outcome in patients after aortic repair for acute type A dissection.

METHODS

One hundred and twenty patients underwent aortic operations with resection of the intimal tear and open distal anastomosis. Median age was 60 years (range 16 to 87); 78 were male. Thirty-six patients had only ascending aortic replacement, 82 had hemiarch repair, and 2 had the entire arch replaced. Retrograde cerebral perfusion was utilized in 66 patients (53%). Rupture defined as free blood in the pericardial space was present in 60 patients (50%). Univariate and multivariate analyses were performed to assess the risk factors for mortality and neurologic dysfunction.

RESULTS

Overall hospital mortality rate was 24.2% +/- 4.0% (+/- 70% confidence level) but did not differ between patients with aortic rupture or without (p = 0.83). The incidence of permanent neurologic dysfunction was 9.4% overall, 10.5% with rupture and 8.3% without rupture (p = 0.75). Multivariate analysis revealed absence of retrograde cerebral perfusion and any postoperative complication as statistically significant indicators for in-hospital mortality (p < 0.05). Overall 1- and 5-year survival was 85.3% and 33.7%; among discharged patients, survival in the nonruptured group was 89% and 37%, versus 81% and 31% in the ruptured group (p = 0.01).

CONCLUSIONS

Aortic rupture at the time of surgery does not increase the risk of hospital mortality or permanent neurologic complications in patients with acute type A dissections. However, aortic rupture at the time of surgery does influence long-term survival.

Effect of hypothermia on cerebral blood flow and metabolism in the pig

BACKGROUND

The pig has become an increasingly popular model for the study of cerebral protection during cardiothoracic surgery in recent years, but little information is available concerning hypothermic porcine physiology. Because the efficacy of cerebral protection depends largely upon metabolic suppression, we studied cerebral oxygen metabolism at various temperatures using two different methods to assess cerebral blood flow (CBF).

MATERIAL AND METHODS

Twelve pigs (7 to 13 kg) underwent cooling on cardiopulmonary bypass to 8 degrees C as recorded by an electrode placed deep in the parenchyma of the brain. CBF was measured in 6 animals using radioactive microspheres and in the other 6 using fluorescent microspheres. CBF, cerebral oxygen consumption, and cerebral vascular resistance were determined at 37 degrees C, 28 degrees C, 18 degrees C, and 8 degrees C.

RESULTS

Both methods produced very similar data. CBF fell steadily with decrease in temperature to 18 degrees C but failed to drop further with more profound hypothermia. With both groups combined, mean cerebral oxygen metabolism was 2.63 mL/100 g per minute at 37 degrees C. Metabolic activity was 50% of base line values at 28 degrees C, 19% at 18 degrees C, and 11% at 8 degrees C. The Q10 value in the pig--the degree of metabolic suppression achieved by a 10 degrees C drop in temperature--is 2.46 (95% confidence interval 2.1 to 2.9); this value is consistent with similar studies in humans.

CONCLUSIONS

The presence of significant residual metabolic activity at 18 degrees C suggests that this degree of hypothermia may provide incomplete cerebral protection during prolonged interruption of CBF. This study demonstrates that cooling to temperatures below 18 degrees C in the pig can achieve greater metabolic suppression although it may be associated with loss of cerebral autoregulation.

Neuroprotection in aortic surgery

Operations on the aortic arch still remain a great challenge for cardiac surgeons and necessitate a period of cerebral blood flow interruption. lt is therefore imperative to protect the brain during this very sensitive time. Clinical as well as experimental studies have shown that the exact mechanism of neural injury seems to be multifactorial. Furthermore it is still uncertain, whether cerebral injury occurs during the interval of HCA or during reperfusion. Various strategies have been adopted in an effort to reduce neurological complications after aortic surgery. These included the use of hypothermic circulatory arrest, antegrade cerebral perfusion and retrograde cerebral perfusion. All these methods have both advantages and disadvantages. New surgical techniques such as cold reperfusion have shown promising results in animal experiments and need further clinical evaluation. One very promising pathway in preventing cerebral injury lies in pharmacological interventions.

Retrograde cerebral perfusion provides negligible flow through brain capillaries in the pig

OBJECTIVES

Although retrograde cerebral perfusion is being used clinically during aortic arch surgery, whether retrograde flow perfuses the brain effectively is still uncertain.

METHODS

Fourteen pigs were cooled to 20 degrees C with cardiopulmonary bypass and perfused retrogradely via the superior vena cava for 30 minutes: 7 underwent standard retrograde cerebral perfusion and 7 underwent retrograde perfusion with occlusion of the inferior vena cava. Antegrade and retrograde cerebral blood flow were calculated by quantitating fluorescent microspheres trapped in brain tissue after the animals were put to death; microspheres returning to the aortic arch, the inferior vena cava, and the descending aorta were also analyzed during retrograde cerebral perfusion.

RESULTS

Antegrade cerebral blood flow was 16 +/- 7.7 mL. min(-1). 100 g(-1) before retrograde cerebral perfusion and 22 +/- 6.3 mL. min(-1). 100 g(-1) before perfusion with caval occlusion (P =.14). During retrograde perfusion, calculations based on the number of microspheres trapped in the brain showed negligible flows (0.02 +/- 0.02 mL. min(-1). 100 g(-1) with retrograde cerebral perfusion and 0.04 +/- 0.02 mL. min(-1). 100 g(-1) with perfusion with caval occlusion; P =.09): only 0.01% and 0.02% of superior vena caval inflow, respectively. Less than 13% of retrograde superior vena caval inflow blood returned to the aortic arch with either technique. During retrograde cerebral perfusion, more than 90% of superior vena caval input was shunted to the inferior vena cava and was then recirculated, as indicated by rapid development of an equilibrium in microspheres between the superior and inferior venae cavae. With retrograde perfusion and inferior vena caval occlusion, less than 12% of inflow returned to the descending aorta and only 0.01% of microspheres.

CONCLUSIONS

The paucity of microspheres trapped within the brain indicates that retrograde cerebral perfusion, either alone or combined with inferior vena caval occlusion, does not provide sufficient cerebral capillary perfusion to confer any metabolic benefit. The slightly improved outcome previously reported with retrograde cerebral perfusion during prolonged circulatory arrest in this model may be a consequence of enhanced cooling resulting from perfusion of nonbrain capillaries and from venoarterial and venovenous shunting.

Cerebral effects of cold reperfusion after hypothermic circulatory arrest

OBJECTIVES

This study was undertaken to explore whether an interval of cold reperfusion can improve cerebral outcome after prolonged hypothermic circulatory arrest.

METHODS

Sixteen pigs (27-30 kg) underwent 90 minutes of circulatory arrest at a brain temperature of 20 degrees C. Eight animals were rewarmed immediately after hypothermic circulatory arrest (controls), and 8 were reperfused for 20 minutes at 20 degrees C and then rewarmed (cold reperfusion). Electrophysiologic recordings, fluorescent microsphere determinations of cerebral blood flow, calculations of cerebral oxygen consumption, and direct measurements of intracranial pressure (millimeters of mercury) were obtained at baseline (37 degrees C), before hypothermic circulatory arrest, after discontinuing circulatory arrest at 37 degrees C deep brain temperature, and at 2, 4, and 6 hours thereafter. Histopathologic features and percent brain water were determined after the animals were sacrificed.

RESULTS

Cerebral blood flow and oxygen consumption decreased during cooling: cerebral oxygen consumption returned to baseline levels after 4 hours, but cerebral blood flow remained depressed until 6 hours in both groups. Cold reperfusion failed to improve electrophysiologic recovery or to reduce brain weight, but median intracranial pressure increased significantly less after cold reperfusion than in controls (P =.02). Although no significant difference in the incidence of histopathologic abnormalities between groups was found, all 3 animals with an intracranial pressure of more than 15 mm Hg after immediate rewarming had histopathologic lesions, and high intracranial pressure was more prevalent among all animals with subsequent histopathologic lesions (P =.03).

CONCLUSIONS

Cold reperfusion significantly inhibited the rise in intracranial pressure seen in control pigs after 90 minutes of circulatory arrest at 20 degrees C, suggesting that cold reperfusion may decrease cerebral edema and thereby improve outcome after prolonged hypothermic circulatory arrest.

Favorable outcome after composite valve-graft replacement in patients older than 65 years

BACKGROUND

Concomitant surgical replacement of the aortic valve and ascending aorta is an ideal treatment for aortic root aneurysms, but there may be hesitation in its use in older patients, despite their known increased risk of rupture. This study was conducted to examine our results in 84 patients older than 65 years undergoing elective aortic root resection with composite valve-graft replacement.

METHODS

Eighty-four patients older than 65 years were operated on between June 1987 and August 1998. Median age was 74 years (range, 66 to 89 years), and 57 patients were men. Seventeen patients were undergoing reoperation. Aortic insufficiency was present in 70 patients. Forty-seven patients received a conduit using a bioprosthesis, whereas in 37 a mechanical valved conduit (St. Jude) was used. The ascending aorta alone was replaced in 23 patients; 50 had hemi-arch replacement, and in 11 the entire aortic arch was replaced.

RESULTS

Hospital mortality was 8.3% (7 of 84). Sixteen late deaths (19%) were noted during a median follow-up of 3.2 years (range, 0 to 10 years). Only one late death was aorta-related. The incidence of thrombotic or hemorrhagic complications was 2.1/100 patient-years, with equal frequency for both mechanical and bioprosthetic valves.

CONCLUSIONS

We conclude that composite valve-graft replacement in elderly patients results in a low operative mortality, yields excellent long-term survival, and averts fatal aneurysm rupture in this high-risk population.

A comparison of complete blood replacement with varying hematocrit levels on neurological recovery in a porcine model of profound hypothermic (<5 degrees C) circulatory arrest

Profound hypothermia (<5 degrees C) may afford better neurological protection after circulatory arrest; however, there are theoretical concerns related to microcirculatory sludging of blood components at these ultra-low temperatures. We hypothesized that at temperatures <5 degrees C, complete blood replacement results in superior neurological outcome. Twelve Yorkshire pigs (30 kg) underwent thoracotomy, cardiopulmonary bypass (CPB), and were randomly assigned to one of three target hematocrits during circulatory arrest: 0%, 5%, 15%. Hextend (6% hetastarch in a balanced electrolyte vehicle) was used for the CPB prime and as an exchange fluid. Animals were cooled to a temperature <5 degrees C, underwent 1-h circulatory arrest, and were warmed to 35 degrees C with administration of blood to increase the hematocrit to >25% before separation from CPB. The primary outcome, peak postoperative neurobehavioral score, was compared between groups. The 0% group (mean +/- SD) had significantly (P: < 0.02) better neurobehavioral scores than the 5% and 15% groups (6.0 +/- 2.9 vs 1.3 +/- 1.0 and 1.5 +/- 0.6) respectively. Other variables (e.g., intracranial pressure) were similar between groups. In a porcine model of profound hypothermia (<5 degrees C) and circulatory arrest, complete blood replacement resulted in superior neurological outcome. This finding suggests that at ultralow temperatures, the presence of some blood component (e.g., erythrocytes, leukocytes) may be deleterious.