The Potential Effect of Epidural Anesthesia on Mesenteric Injury after Supraceliac Aortic Clamping in a Rabbit Model.

BACKGROUND: Epidural anesthesia is known to increase blood flow by producing vasodilatation on mesenteric circulation. In this experimental study, we aim to examine the effect of epidural anesthesia on mesenteric ischemic-reperfusion (IR) injury induced by supracoeliac aortic occlusion in a rabbit model. METHODS: Twenty-eight male white New Zealand rabbits were assigned into 4 separate groups, with 7 rabbits in each group: group I, control group; group II, IR-only group; group III, IR plus epidural anesthesia group; group IV, epidural anesthesia-only group. IR model was produced by clamping supraceliac aorta with an atraumatic vascular clamp for 60 min, followed by reperfusion for 120 min. An epidural catheter was placed via Th12-L1 intervertebral space by using open technique before aortic clamping in those assigned to epidural anesthesia. IR injury was assessed using blood markers interleukin-6 and IMA and tissue markers superoxide dismutase and malondialdehyde. Also histopathological examination was performed to evaluate the degree of injury. RESULTS: All biochemical markers in group II were significantly elevated in comparison with the other 3 groups (p < 0.05). This was paralleled by a more severe histopathological injury in IR- only group (group II). The group receiving IR plus epidural anesthesia (group III) had lower biochemical marker levels as compared with the IR-only group (group II). CONCLUSIONS: Mesenteric IR injury that can occur during abdominal aorta surgery can be reduced by epidural anesthesia, which is commonly used during or after major operations for pain control. Controlled clinical studies are required to evaluate these findings.

Prevalence of and risk factors for early postoperative arrhythmia in children after cardiac surgery.

BACKGROUND: The aims of this study were to (i) evaluate postoperative arrhythmias following congenital heart surgery, on 12-lead electrocardiography and Holter monitoring; and (ii) analyze the association between the type of repair and postoperative arrhythmia. METHODS: A total of 229 children and 10 neonates with a mean age of 4.71 ± 0.41 years (range, 15 days-17 years) who underwent congenital cardiac surgery were included the study. Twelve-lead electrocardiography and Holter monitoring were used to evaluate arrhythmias after the operation. RESULTS: Within the evaluation period, 104 patients (43.5%) developed arrhythmias after surgery. No arrhythmias were observed in neonates. Female sex (51.9%) was slightly associated with the occurrence of arrhythmias after operation. The most common arrhythmia was supraventricular extra-systoles (65.4%). Risk factors for supraventricular extra-systoles were repair of secundum atrial septal defect (32.3%), ventricular septal defect (25%) and tetralogy of Fallot (14.7%). Also, ventricular extra-systoles were associated with repair of ventricular septal defect. CONCLUSIONS: Postoperative arrhythmia is usually a frequent and transient phenomenon after congenital cardiac surgery, and is provoked by both mechanical irritation of the conduction system and humoral factors. Postoperative arrhythmia should be anticipated in patients with congenital cardiac surgery. Finally, the association between this type of surgical repair and arrhythmia may be helpful for estimating the type of arrhythmia that develops after congenital cardiac surgery in children.

Ventricular assist device outflow-graft site: effect on myocardial blood flow.

BACKGROUND: Recent advances in left ventricular assist device (LVAD) technology have resulted in small, durable, energy-efficient, continuous-flow blood pumps that can support patients with end-stage heart failure. However, the effects of reduced or nonpulsatile flow on end-organ function are unclear. We performed a pilot study in calves with a continuous-flow LVAD to assess the effects of the pump's outflow-graft location (ascending versus descending aorta) on myocardial blood flow. MATERIALS AND METHODS: In 8 healthy calves, we implanted the Jarvik 2000 LVAD in the left ventricular apex without the use of cardiopulmonary bypass. We anastomosed the outflow graft to either the ascending aorta (group 1; n = 4) or the descending aorta (group 2; n = 4). Hemodynamic parameters, myocardial oxygen consumption, and regional myocardial blood flow (analyzed with colored microspheres) were assessed at baseline (pump off) and during pump operation at 8000, 10,000, and 12,000 rpm. RESULTS: No intergroup differences were found in the aortic pressure, heart rate, central venous pressure, pump-flow to total-cardiac-flow ratio, or blood flow in the left anterior descending and right posterior descending coronary arteries at increasing pump speeds. Neither myocardial oxygen consumption nor myocardial tissue perfusion differed significantly between the two groups. CONCLUSIONS: Regardless of the outflow-graft location (ascending versus descending aorta), the continuous-flow LVAD unloaded the left ventricle and did not adversely affect myocardial perfusion in either the right or left ventricle. Owing to the small number of animals studied, however, the most we can conclude is that neither outflow-graft location appeared to be inferior to the other.

Anti-inflammatory and anti-fibrotic effects of sirolimus on bleomycin-induced pulmonary fibrosis in rats.

PURPOSE: Pulmonary fibrosis is a devastating disease with a poor prognosis. Although the diagnosis and pathophysiology of this disease have been better characterized over the past few years, there is no effective therapy for the disease. The aim of this study was to evaluate the anti-inflammatory and anti-fibrotic effects of sirolimus (SRL), which is a potential anti-fibrotic agent, by using bleomycin (BLM)-induced pulmonary fibrosis model in rats. METHODS: A single intra-tracheal injection of BLM (2.5 U/kg) was administered and sirolimus (2.5 mg/kg/day) was given orally, beginning either one day before (early SRL) or nine days after (late SRL) the BLM administration. The effect of SRL on fibrosis was studied by analysis of cytokine levels in BAL fluid, measurement of lung tissue hydroxyproline (HPL) content and histopathological examination. RESULTS: Both early and late SRL administrations caused a decrease in the levels of IL-13, PDGF-A and TGF-ß1 (p=0.001) and an increase in IFN-γ levels (p=0.001) in BAL fluid. Early and late SRL also caused a decrease in HPL content (p=0.001). Early sirolimus caused a significant decrease in fibrosis score (p=0.001), while late SRL did not. CONCLUSION: Sirolimus was effective in BLM-induced pulmonary fibrosis model, especially in the early phases of the disease.

Correlation of ischemic area and coronary flow with ameroid size in a porcine model.

BACKGROUND: Ameroid constriction has long been used to induce chronic hibernating myocardium in animal models. MATERIALS AND METHODS: Thirty-six pigs underwent surgical implantation of an ameroid constrictor around their left circumflex (LCx) coronary artery. The device had an internal diameter of 2.25 (n=9), 2.50 (n=16), or 2.75 (n=11) mm. Thrombolysis in Myocardial Infarction (TIMI) grade coronary flow was assessed angiographically during device placement and on postoperative d 30. The ischemic and total left ventricular (LV) areas were measured with endocardial voltage mapping (NOGA) on d 30. RESULTS: For ameroid constrictor diameters of 2.25, 2.50, and 2.75 mm, the ratio of the ischemic area versus the total LV area averaged 24% ± 10%, 21% ± 6%, and 23% ± 9%, respectively (P=NS). Coronary angiography revealed complete LCx occlusion in all animals. TIMI grade-1 flow was the statistical mode for all groups and was independent of constrictor diameter. Normalization of the device diameter with the vessel diameter did not affect the statistical results. CONCLUSIONS: For the range of ameroid constrictor sizes evaluated in this study, coronary flow and the ischemic LV area were independent of device size. The ischemic area and coronary flow created by ameroid constrictor placement were highly homogeneous and accurate for an experimental model of hibernating myocardium.

Tezosentan reduces the renal injury induced by abdominal aortic ischemia-reperfusion in rats.

BACKGROUND: Renal injury induced by aortic ischemia-reperfusion (IR) is an important factor in the development of postoperative acute renal failure following abdominal aortic surgery. Endothelin (ET) is involved in the development of renal injury induced by aortic IR and tezosentan (R0 61-0612) is a specific ET receptor antagonist. The aim of this study was to examine the effect of tezosentan on renal injury induced by abdominal aortic IR in rats. MATERIAL AND METHODS: Twenty-four Wistar-Albino rats were randomized into three groups (eight per group). Control group underwent laparotomy and dissection of the infrarenal abdominal aorta (IAA) without occlusion. The aortic IR group underwent laparotomy and clamping of the IAA for 120 min followed by 120 min of reperfusion. Aortic IR + tezosentan group underwent same aortic IR periods, and received a bolus intravenous injection of 10 mg/kg tezosentan before ischemia plus continuous intravenous infusion of 1 mg/kg/h tezosentan during 120 min ischemia and 120 min reperfusion. At the end of the experiment, blood and kidney tissue specimens were obtained for biochemical analysis. Histological evaluation of the rat kidney tissues was also done. RESULTS: Biochemical analysis showed that aortic IR significantly increased (P < 0.05 versus control) while tezosentan significantly decreased (P < 0.05 versus aortic IR) the tissue levels of malondialdehyde, superoxide dismutase, catalase and myeloperoxidase. Histological analyses showed that aortic IR significantly increased (P < 0.05 versus control) while tezosentan significantly decreased (P < 0.05 versus aortic IR) focal glomerular necrosis, dilatation of Bowman's capsule, degeneration of tubular epithelium, necrosis in tubular epithelium and tubular dilatation in the renal tissue samples. CONCLUSION: The results of this study indicate that tezosentan reduces renal injury induced by aortic IR in rats. We think that tezosentan exerted this beneficial effect via reducing oxidative stress and lipid peroxidation, inhibition of leukocyte infiltration into renal tissue and acting cytoprotective on renal tubular cells after aortic IR.

Endothelin receptor antagonism by tezosentan attenuates lung injury induced by aortic ischemia-reperfusion.

Tezosentan is a novel dual endothelin receptor antagonist. The purpose of this study was to examine the effect of tezosentan on lung injury induced by abdominal aortic ischemia-reperfusion (IR) in rats. Thirty-two Wistar-albino rats were randomized into four groups (eight per group) as follows: control group (sham laparotomy), aortic IR group (120 min ischemia and 120 min reperfusion), aortic IR + tezosentan group (a bolus intravenous injection of 10 mg/kg tezosentan before ischemia plus continuous intravenous infusion of 1 mg/kg/hr tezosentan during 120 min ischemia and 120 min reperfusion), and control + tezosentan. Blood and lung tissue samples were obtained for biochemical analysis. Protein concentrations in bronchoalveolar lavage fluid and lung wet/dry weight ratios were measured. A histological evaluation was also done. Aortic IR significantly increased (p < 0.05 vs. control group) and tezosentan significantly decreased (p < 0.05 vs. aortic IR group) the plasma level of tumor necrosis factor-alpha; lung tissue levels of malondialdehyde, catalase, and myleperoxidase; and protein concentration in bronchoalveolar lavage fluid and lung wet/dry weight ratio. Histological evaluation showed that tezosentan attenuated the morphological changes associated with lung injury. The results of this study indicate that tezosentan attenuates lung injury induced by aortic IR in rats. We propose that this protective effect of tezosentan is due to (1) reduced systemic inflammatory response, (2) reduced oxidative stress and lipid peroxidation in lung tissue, (3) reduced pulmonary microvascular leakage, and (4) inhibition of leukocyte infiltration into lung tissue.

Successful mitral valve surgery in a patient with myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune disease characterized by a weakness of the muscles with remissions and exacerbations due to antibodies against acetylcholine receptors. Most of the patients die because of a respiratory failure toward the end of the disease. A 49-year-old male patient with MG in whom a thymectomy operation had been performed five years ago had dyspnea, palpitation, and chest pain during his admission. After his examination, a severe mitral regurgitation was detected, and he underwent a successful mitral valve replacement. A general anesthesia management was performed using sufentanyl and propophol without any muscle relaxant agent. He was extubated seven hours after the surgery. He had difficulty in swallowing at postoperative day three, and his medication doses were increased. He was discharged from the hospital at postoperative day seven without any complication. MG is a rare disease and may cause morbid complications during the cardiac surgery, but can be successfully managed.

The effect of coronary revascularization on new-onset complete atrioventricular block due to acute coronary syndrome.

BACKGROUND: Coronary artery disease is one of the most common causes of complete atrioventricular block (AVB) in adults. In this study, we evaluated whether prompt revascularization of the coronary artery occlusion can ameliorate new-onset complete AVB due to acute coronary syndrome (ACS). METHODS: Five patients (4 men and 1 woman) with a mean age of 69.8+/-7.1 years with diagnosed new-onset complete AVB and proven coronary artery disease were enrolled in the study. At the time of AVB diagnosis, 3 of the patients had acute myocardial infarction, and the other 2 patients had unstable angina pectoris. All patients underwent complete coronary bypass surgery after the diagnosis of complete AVB. A patient who underwent 2 coronary bypasses also underwent aortic valve replacement. RESULTS: No mortality was observed in the study group. All but one of the patients converted back to sinus rhythm after a mean interval of 30+/-13.6 hours following revascularization procedures. Complete AVB persisted in 1 patient, and a permanent pacemaker was implanted. All patients were discharged uneventfully. The mean hospital stay was 11.4+/-4.5 days. All patients are still being followed up after surgery; at a mean follow-up of 27.4+/-0.9 months, there have been no further problems. CONCLUSION: Coronary revascularization may ameliorate ACS-related new-onset complete AVB with an acceptable rate of successful reversion to sinus rhythm. An especially appropriate time for surgery, complete coronary revascularization, and management of myocardial protection during surgery might improve the results of coronary bypass procedures in these patients.

Endothelin receptor blockade with tezosentan ameliorates myocardial injury induced by abdominal aortic ischemia-reperfusion.

Endothelin is both a potent vasoconstrictor and an important mediator of ischemia-reperfusion (IR) injury. Therefore, the role of endothelin receptor antagonism in IR-induced-tissue injury carries great interest. Here, we examined the effect of tezosentan, a nonselective antagonist for endothelin receptors, on myocardial injury induced by abdominal aortic IR, which represents a model of the IR injury in distant organs frequently occurred after vascular surgery. Thirty-two Wistar rats were randomized into four groups (n = 8) as follows: control (sham laparotomy), aortic IR (120 min ischemia and 120 min reperfusion), aortic IR + tezosentan (10 mg/kg intravenous injection before ischemia plus continuous intravenous infusion of 1 mg/kg/hr during the IR injury), and control + tezosentan. Biochemical analysis showed that aortic IR significantly increased (p < 0.05 vs control) the plasma levels of troponin-I, interleukin-6 and tumor necrosis factor-alpha, and the myocardial tissue levels of malondialdehyde, superoxide dismutase and catalase, whereas tezosentan significantly decreased these same factors (p < 0.05 vs aortic IR). Histological evaluation also showed that aortic IR significantly increased (p < 0.05 vs control) myocardial disorganization, myofiber swelling and myofiber eosinophilia in myocardial tissue samples, whereas tezosentan significantly decreased these factors (p < 0.05 vs aortic IR). These results indicate that tezosentan has protective effects against myocardial injury induced by abdominal aortic IR in rats. We propose that the mechanisms underlying this protective effect of tezosentan involves the reduction of oxidative stress and subsequent lipid peroxidation, the inhibition of systemic inflammatory response, and acting cytoprotective on myocytes after aortic IR.

Comparison of different dose regimens of enoxaparin in deep vein thrombosis therapy in pregnancy.

INTRODUCTION: Pregnant women have a higher risk of developing deep vein thrombosis (DVT) and consequent thrombogenic events, including pulmonary embolisms. Low-molecular-weight heparin (LMWH) products have been shown to successfully treat DVT with few significant side effects. The purpose of this study was to compare the effects of two dose regimens of enoxaparin (a LMWH) in the management of DVT in pregnancy. METHODS: A total of 35 pregnant patients with DVT were enrolled in this study. As first-line anticoagulation therapy, patients were administered an intravenous unfractionated heparin infusion for 5 days, followed by a subcutaneous injection of enoxaparin 1 mg/kg twice a day until discharge. The enoxaparin therapy continued at home with 1 mg/kg twice a day for 18 patients (group I) and 1.5 mg/kg once a day for the other 17 patients (group II). Enoxaparin was discontinued 12-24 hours before delivery and restarted within 8-12 hours after delivery. Warfarin was given as adjuvant therapy along with enoxaparin in the post-partum period. Enoxaparin was discontinued when an international normalised ratio of 2 or above was reached. Differences between the two groups in terms of therapy response, complications and efficacy were recorded. RESULTS: Thrombophilic disease was observed in three patients in each group. The iliac vein had the highest incidence of DVT in both groups. During therapy, two patients in group I were diagnosed with a mild haemorrhage; one patient (in group II) had abortion. There were no significant differences between groups in terms of recanalisation (measured by venous ultrasonography examination), post-thrombotic symptoms or safety parameters. CONCLUSION: Enoxaparin can be used safely in DVT therapy during pregnancy. Our results indicate that therapy consisting of a single daily dose of 1.5 mg/kg enoxaparin is as effective as twice-daily administration.

Relationship between site of myocardial infarction, left ventricular function and cytokine levels in patients undergoing coronary artery surgery.

BACKGROUND: The purpose of this study was to examine the relationship between left ventricular (LV) function, cytokine levels and site of myocardial infarction (MI) in patients undergoing coronary artery bypass grafting (CABG). METHODS: Sixty patients undergoing CABG were divided into three groups (n = 20) according to their history of site of myocardial infarction (MI): no previous MI, anterior MI and posterior/inferior MI. In the pre-operative period, detailed analysis of LV function was done by transthoracic echocardiography. The levels of adrenomedullin, interleukin-1-beta, interleukin-6, tumour necrosis factor-alpha (TNF-α) and angiotensin-II in both peripheral blood samples and pericardial fluid were also measured. RESULTS: Echocardiographic analyses showed that the anterior MI group had significantly worse LV function than both the group with no previous MI and the posterior/inferior MI group (p < 0.05 for LV end-systolic diameter, fractional shortening, LV end-systolic volume, LV end-systolic volume index and ejection fraction). In the anterior MI group, both plasma and pericardial fluid levels of adrenomedullin and and pericardial fluid levels of interleukin-6 and interleukin- 1-beta were significantly higher than those in the group with no previous MI (p < 0.05), and pericardial fluid levels of adrenomedullin, interleukin-6 and interleukin-1-beta were significantly higher than those in the posterior/inferior MI group (p < 0.05). CONCLUSIONS: The results of this study indicate that (1) patients with an anterior MI had worse LV function than patients with no previous MI and those with a posterior/inferior MI, and (2) cytokine levels in the plasma and pericardial fluid in patients with anterior MI were increased compared to patients with no previous MI.

Right ventricle-sparing left ventricular resection and replacement with a continuous-flow rotary blood pump: an in vivo experiment.

Despite recent advances in left ventricular assist device and total artificial heart technologies, these devices are still so large that they pose a significant problem in small patients with refractory heart failure. Excising the left ventricle while preserving the right ventricle--and then replacing the left ventricle with a mechanical pump--has been proposed as an alternative approach to this problem. We conducted a pilot study to evaluate possible surgical techniques and the hemodynamic effects of right ventricle-sparing left ventricular resection and replacement with a continuous-flow rotary blood pump in a healthy bovine model.

The effect of iloprost on renal dysfunction after renal I/R using cystatin C and beta2-microglobulin monitoring.

The purpose of this study was to investigate the effect of iloprost, a cytoprotective prostacyclin analog, on renal injury during unilateral renal I/R in rats and to determine whether the levels of serum cystatin C (CyC) and beta2-microglobulin (B2M), as markers of glomerular function, might denote this injury. Thirty-two Wistar rats were randomized into four groups (n = 8) as follows: control (sham laparotomy), renal I/R (60-min left renal ischemia and 120-min reperfusion), renal I/R + iloprost (20 ng kg(-1) min(-1) infusion during renal I/R period, i.v.), and control + iloprost. Blood and kidney tissue samples were obtained for biochemical and histological analysis from all rats. Serum urea, creatinine, CyC, and B2M levels were evaluated for biochemical analysis. Histopathological changes in renal structure were examined for histological analysis. Serum urea, creatinine, and CyC levels were significantly increased in the renal I/R group. Iloprost treatment decreased these three markers in the renal I/R + iloprost group. beta2-Microglobulin levels were not significantly changed in any group. Histological analyses showed that renal I/R elicited significant renal injury, whereas iloprost significantly decreased I/R-induced renal injury. Serum CyC level is one of the good indicators of acute renal damage due to I/R produced by renal artery occlusion. In contrast, we have shown that there are no significant changes in the levels of serum B2M levels that would make it an accurate diagnostic tool for detecting acute changes in renal injury subject to renal I/R in rats.

Repair of coarctation-related aortic arch aneurysm and ventricular septal defect in an adolescent.

A saccular aortic arch aneurysm that is secondary to aortic arch coarctation and that is accompanied by a ventricular septal defect is a rare combination in the adolescent patient. Total simultaneous repair of all of these conditions is desirable, because of the higher morbidity and mortality rates of staged procedures-particularly when resection of the saccular aneurysm is delayed. Herein, we discuss the case of a 16-year-old boy who underwent simultaneous surgical correction of these malformations. With the aid of cardiopulmonary bypass on the beating heart, the coarctation and the aneurysmal segment were resected, and a tubular Dacron graft was interposed. The ascending aorta and femoral artery were both then cannulated to ensure whole-body perfusion during cardiopulmonary bypass. The ventricular septal defect was closed with the patient under cardioplegic arrest. After 10 days, he was discharged from the hospital without sequelae. We conclude that single-staged repair of cardiac abnormalities and of an aortic arch aneurysm that is secondary to coarctation of the aortic arch can be performed safely and effectively in adolescent and adult patients by use of our technique.

Surgical treatment of postinfarction pseudoaneurysms of the left ventricle.

BACKGROUND: Left ventricular pseudoaneurysm is a rare and frequently fatal complication of acute myocardial infarction. It occurs as a consequence of rupture of the ventricular free wall that gets confined by a portion of the pericardium. The purpose of this study was to present our surgical experience of postinfarction left ventricular pseudoaneurysms and to evaluate mid-term results. METHODS: The study population comprised five symptomatic patients diagnosed with left ventricular pseudoaneurysm and treated surgically in a short period of time. There were three males and two females. The mean age of the patients was 66.8 +/- 10.8 years. The diagnosis was made initially by echocardiography and subsequently confirmed by angiography. An additional cardiac magnetic resonance imaging study was performed in three patients. Surgical resection of the pseudoaneurysm was combined with an endoaneurysmorrhaphy procedure in all patients. Associated cardiac operations were performed in three patients. Definitive diagnosis of pseudoaneurysm was confirmed by histopathological evaluation of the excised wall in all patients. RESULTS: All patients survived the operation and were discharged to home care. The mean duration of hospital stay was 11.6 +/- 4.6 days. Patients were either in class I or II of New York Heart Association classification at discharge. All patients are still being followed after surgery with a mean follow-up period of 10.4 +/- 6.6 months with no further problems. CONCLUSION: Surgical repair is indicated in left ventricular pseudoaneurysm as it carries a high risk of rupture and sudden cardiac death. Surgical repair combined with an endoaneurysmorrhaphy procedure carries a low mortality risk and improves functional capacity.

Left ventricular rhabdomyoma with severe left ventricular outflow tract obstruction: development of delayed hemiplegia after cardiopulmonary bypass.

The incidence of cardiac tumors increased with the improvement of imaging techniques in infants. Rhabdomyomas are the most common tumors in this group of patients. We herein report a 40-day-old male patient with left ventricular rhabdomyoma. The tumor caused syncope attack and supraventricular tachycardia. An emergency operation was planned and the life-threatening lesion was excised via left ventriculotomy. The patient was extubated on postoperative sixth hour and discharged from hospital on the sixth day of the postoperative period without any problem. This successful operation encourages us not to hesitate to perform an operation in newborns with cardiac neoplasms causing hemodynamic instability.