Aprikalim a potassium adenosine triphosphate channel opener reduces neurologic injury in a rabbit model of spinal cord ischemia

BACKGROUND

Potassium adenosine triphosphate (KATP) channel openers have been involved in the enhancement of ischemic tolerance in various tissues. The purpose of the present study is to evaluate the effects of aprikalim, a specific KATP channel opener, on spinal cord ischemic injury.

METHODS

Fifty-four rabbits were randomly assigned to three groups: group 1 (n = 18, sham operation), group 2 (n = 18, 30 min of normothermic aortic cross-clamping) and group 3 (n = 18, aprikalim 100 μg/kg was administered 15 min before 30 min of normothermic aortic cross-clamping). Neurologic evaluation was performed according to the modified Tarlov scale. Six animals from each group were sacrificed at 24, 48 and 168 h postoperatively. The lumbar spinal cords were harvested and examined histologically. The motor neurons were counted and the histologic lesions were scored (0-3, 3: normal).

RESULTS

Group 3 (aprikalim group) had better Tarlov scores compared to group 2 at all-time points (P < 0.025). The histologic changes were proportional to the Tarlov scores and group 3 had better functional outcome as compared to group 2 at 168 h (number of neurons: 21.2 ± 4.9 vs. 8.0 ± 2.7, P < 0.001 and histologic score: 1.67 ± 1.03 vs. 0.50 ± 0.55, P = 0.03). Although aprikalim exhibited improved effect on clinical and histologic neurologic outcome when compared to normothermic spinal cord ischemia, animals in group 3 had worse Tarlov score, reduced number of motor neurons and worse histologic score when compared to group 1 (sham operation) at 168 h (P = 0.003, P = 0.001 and P = 0.019 respectively).

CONCLUSION

Aprikalim reduces the severity of spinal cord ischemic injury in a rabbit model of spinal cord ischemia.

Treatment with simvastatin inhibits the formation of abdominal aortic aneurysms in rabbits

BACKGROUND

Abdominal aortic aneurysm (AAA) is a common and lethal disease. AAAs are associated with atherosclerosis, chronic inflammation, and extracellular matrix degradation. The aim of this study was to determine whether treatment with simvastatin can influence the development of experimental aortic aneurysms in a rabbit model.

MATERIALS AND METHODS

A total of 76 rabbits were randomized in four groups: in group I (n = 12), where the abdominal aortas were exposed to 0.9% NaCl, and in group II (n = 24), group III (n = 24) and group IV (n = 18), where the aortas were exposed to CaCl2 0.5 mol/L for 15 minutes after laparotomy. Group III received 2 mg/kg simvastatin daily starting 7 days before laparotomy, and in group IV, the daily treatment with simvastatin started 7 days after laparotomy. Animals were sacrificed at intervals of first, second, third, and fourth week to obtain measurements of aortic diameter and histological examination. Moreover, immunohistochemistry was used in order to examine the relative distribution of matrix metalloproteinases (MMPs) 2 and 9 (MMP-2 and MMP-9, respectively) and tissue inhibitor 1 of MMPs within the aortic aneurysms.

RESULTS

The increase of aortic diameter in animals of group I ranged from 4.6% to 7.6%; in group II, from 41% to 85% (P < 0.001 vs. group I); in group III, from 9% to 18% (group II vs. group III, P < 0.001); and in group IV; from 36% to 38%. Moreover, aortic specimens of group II presented a statistically significant increase in MMP-2 and MMP-9 immunoexpression compared with other groups (I, III, IV) (P < 0.05 for all comparisons), with the exception of animals of group IV at the end of second week. Immunoreactivity of tissue inhibitor 1 of MMPs was not statistically different among groups II, III, and IV.

CONCLUSIONS

Simvastatin may prove clinically significant in suppressing the development and expansion of AAAs and, thereby, in reducing the risk of rupture and the need for repair.

Does hypothermic circulatory arrest or prolonged cardiopulmonary bypass time affect early outcome in reoperative aortic surgery?

AIM

Prolonged cardio-pulmonary bypass (CPB) time, usually necessary for reoperations, is known to increase mortality in coronary bypass procedures and aortic reoperations. We investigated if prolonged CPB time and arch reconstruction in reoperations of the thoracic aorta affect in-hospital outcome.

METHODS

Twenty-nine patients underwent reoperations on the thoracic aorta. The reoperations performed were aortic root replacement with composite graft without aortic arch involvement in ten patients, isolated ascending aorta replacement in six patients, aortic arch replacement as a primary procedure in two patients, and aortic arch in conjunction with ascending or descending aorta replacement in 11 patients.

RESULTS

Fourteen patients had aortic reoperation with deep hypothermic circulatory arrest (DHCA) and 15 without DHCA. The in-hospital mortality rate was 13.8%. The use deep hypothermic circulatory arrest or CPB time did not affect early outcome. Previous coronary artery bypass procedure was independent predictor of in-hospital mortality. Seven patients required re-exploration for bleeding. One patient suffered from stroke and finally five patients had prolonged ventilation, two requiring tracheostomy. There have been no deaths in the follow-up period. None of the patients has required repeat surgical intervention on the heart or the aorta.

CONCLUSION

The use of DHCA or prolonged CPB time do not affect early outcome in reoperations of the thoracic aorta.

Differential expression of collagen type V and XI alpha-1 in human ascending thoracic aortic aneurysms

BACKGROUND

The molecular mechanisms leading to ascending thoracic aortic aneurysms (ATAAs) remain unknown. We hypothesized that alterations in expression levels of specific fibrillar collagens occur during the aneurysmal process.

METHODS

Surgical samples from ascending aortas from patients with degenerative ATAAs were subdivided by aneurysm diameter: small, 5 to 6 cm; medium, 6 to 7 cm; and large, greater than 7 cm; and compared with nonaneurysmal aortas (mean diameter, 2.3 cm).

RESULTS

Histology, immunofluorescence, and electron microscopy demonstrated greater disorganization of extracellular matrix constituents in ATAAs as compared with control with an increase in collagen alpha1(XI) within regions of cystic medial degenerative lesions. Real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) showed collagens type V and alpha1(XI) were significantly and linearly increased in ATAAs as compared with control (p < 0.001). There was no change in the messenger ribonucleic acid (mRNA) expression levels of collagens type I and III. Western blot analysis showed collagens type I and III were significantly decreased and collagens alpha1(XI) and V were significantly increased and were linearly correlated with the size of the aneurysm (p < 0.001 for both).

CONCLUSIONS

These results demonstrate that increased collagen alpha1(XI) and collagen V mRNA and protein levels are linearly correlated with the size of the aneurysm and provide a potential mechanism for the generation and progression of aneurysmal enlargement.

The impact of left ventricular hypertrophy on early and long-term survival after coronary artery bypass grafting

BACKGROUND

Left ventricular hypertrophy (LVH) can itself contribute to increased rates of cardiovascular events. We sought to determine the impact of LVH on in-hospital and long-term mortality after coronary artery bypass grafting (CABG).

METHODS

Between 1992 and 2003, 4140 consecutive patients underwent CABG. Long-term survival data (mean follow-up 7.0 years) were obtained from the National Death Index. The impact of LVH on in-hospital mortality was determined by multivariate logistic regression analysis. Patients with and without LVH were compared by Cox proportional hazard models and risk-adjusted Kaplan-Meier curves.

RESULTS

There were 977 patients (23.6%) with LVH. Their mean EuroSCORE was 7.4 +/- 3.4 and there were 40 in-hospital deaths (4.1%) in this group. Multivariate logistic regression showed that patients with LVH had less elective operations, higher Canadian Cardiovascular Society Functional Class, more previous myocardial infarctions and higher percentages of 3-vessel disease, hypertension, current congestive heart failure, malignant ventricular arrhythmias, chronic obstructive pulmonary disease, calcified aorta, low ejection fraction, intravenous nitroglycerine, previous percutaneous coronary interventions and smoking. After adjustment for all available pre, intra and postoperative variables LVH was not an independent predictor for in-hospital mortality (OR 1.04, 95% CIs 0.60-1.81, P = 0.891). Risk-adjusted Kaplan-Meier survival curves showed decreased long-term survival in patients with LVH after the first 3 years (HR 1.24, 95% CIs 1.06-1.44, P = 0.006).

CONCLUSIONS

Patients with LVH showed similar in-hospital mortality when compared with patients without LVH. However, LVH was a detrimental risk factor for late mortality, especially after the third postoperative year. These data suggest the need for a more frequent long-term follow-up among patients with LVH undergoing CABG.

Independent predictors for early and long-term mortality after heart valve surgery

BACKGROUND AND AIM OF THE STUDY

Patients with heart valve surgery may have a periprocedural mortality extending up to one year after surgery. The study aim was to determine independent predictors for in-hospital and long-term mortality after heart valve surgery.

METHODS

A total of 1,376 consecutive patients who underwent isolated or combined heart valve surgery at a single institution was studied. Multivariate logistic regression analysis was used to determine independent predictors for in-hospital mortality. Long-term survival data (mean follow up 5.6 years) were obtained from the National Death Index. Multivariate Cox regression analysis was used to determine independent predictors for long-term mortality. All available preoperative, intraoperative and postoperative risk factors were included in these analyses.

RESULTS

The mean EuroSCORE was 6.2 +/- 3.7. There were 86 (6.3%) in-hospital and 550 (40.0%) late deaths. Eleven independent predictors were determined for in-hospital mortality, and 13 for long-term mortality. There were six common independent predictors (preoperative dialysis, total bypass time, intraoperative stroke, postoperative sepsis and/or endocarditis, renal and respiratory failure). Unique independent predictors for in-hospital mortality included intra-aortic balloon pump, preoperative endocarditis, intravenous use of nitroglycerine, bleeding requiring reoperation and gastrointestinal complications. The model for in-hospital mortality showed acceptable calibration (Lemeshow-Hosmer, p = 0.629) and excellent discriminatory ability (C statistic 0.88). Unique independent predictors for long-term mortality included age, ejection fraction, stroke prior to surgery, hemodynamic instability, chronic obstructive pulmonary disease and deep sternal wound infection.

CONCLUSION

Independent predictors were determined for early and long-term mortality after heart valve surgery. The prevention of postoperative complications may be a key element for increased early and long-term survival in these patients.

Thoracoscore predicts midterm mortality in patients undergoing thoracic surgery

OBJECTIVE

Thoracoscore is the first multivariate model for the prediction of in-hospital mortality after general thoracic surgery. We aimed to evaluate the performance of Thoracoscore in predicting in-hospital and midterm all-cause mortality.

METHODS

We retrospectively evaluated 1675 patients who underwent thoracic surgery (lung resections [n = 626], mediastinum [n = 535], pleura and pericardium [n = 268], esophagus [n = 88], chest wall [n = 90], trachea [n = 45], and other procedures [n = 23]) from October 2002 to March 2006 at a single institution. Midterm survival data (mean follow-up 25 +/- 16 months) were obtained from the National Death Index. Kaplan-Meier survival plots of the quartiles of Thoracoscore were constructed and compared with the log-rank test with adjustment for trend.

RESULTS

Starting from the lower-risk to the higher-risk quartile, the in-hospital mortality rates were 0% (0/418), 1% (4/415), 2.5% (11/435), and 9.6% (54/407). Thoracoscore was a strong independent predictor for in-hospital mortality (odds ratio 1.20, 95% confidence intervals 1.15-.25; P < .001). The 2-year survivals of the Thoracoscore quartiles were 98.7% +/- 0.6%, 87.0% +/- 1.8%, 73.8% +/- 2.3%, and 54.8% +/- 2.7%, respectively (P < .0001). Thoracoscore was a strong independent predictor for midterm mortality (hazard ratio 1.12, 95% confidence intervals 1.11-1.14; P < .001).

CONCLUSION

Thoracoscore is a good and useful clinical tool for preoperative prediction of in-hospital and midterm mortality among patients undergoing general thoracic surgery.