Ischemia In Adults Research Articles

Transmesenteric hernia: A rare cause of bowel ischaemia in adults

INTRODUCTIONTransmesenteric herniae are a rare cause of bowel ischaemia in adults with few reported cases in published literature. PRESENTATION OF CASEWe report a rare case of a 26-year-old female with spontaneous transmesenteric hernia of jejunum and proximal ileum due to a congenital mesenteric defect resulting in bowel gangrene, presenting initially with no haemodynamic or biochemical abnormalities. The hernia was reduced, small bowel resected and primary side to side anastomosis performed, following which the patient made a good recovery and was discharged 5 days later. DISCUSSIONThe insidious onset of transmesenteric herniae and lack of specific radiological or laboratory investigations reaffirms the importance of surgeons maintaining a high index of suspicion for this critical surgical emergency. CONCLUSIONClose monitoring of the patient's general condition in cases of non-specific abdominal pain is essential to identify the rare deteriorating patient for early surgical intervention and optimal outcome.

Non-atherosclerotic causes of myocardial ischemia in adults encountered in our centre: A retrospective analysis

BackgroundWe routinely treat young patients with myocardial infarction with no conventional risk factors for atherosclerosis other than smoking. Angiogram in such patients usually shows either a recanalized artery or evidence of thrombus. We aimed at deciphering non atherosclerotic causes of ischemia at our centre. MethodsWe serially analyzed 1500 diagnostic angiograms done at our center over a period of one year, with all patients above eighteen years of age. A retrospective analysis of presentation, risk factors and treatment and outcome (when available) was done. ResultsCoronary artery thrombosis was most common cause ( 5 patients), followed by coronary artery dissection (3) and coronary artery embolisation (2) patients. Takayasu arteritis and anamoulus origin of coronary artery were other causes. ConclusionOur study suggests that coronary artery thrombosis is most common non atherosclerotic cause of myocardial infarction and may respond favorably to thrombolytic treatment.

Utility of exercise stress echocardiography in pediatric cardiac transplant recipients: A single-center experience

Annual coronary angiography (ANG) to assess for significant epicardial coronary artery disease (CAD) is an integral part of follow-up care for pediatric cardiac transplant recipients at Children's Hospital Boston. Exercise stress echocardiography (ESE) is an important, non-invasive tool for the detection of ischemia in adults but has been rarely used in children. Therefore, the aim of this study was to assess the feasibility and utility of ESE in excluding ANG-detected epicardial CAD at our center, where ESE has been implemented since 2007. We conducted a retrospective review of all pediatric cardiac transplant recipients at our institution who had undergone ESE and ANG between January 2007 and December 2010, and with testing performed < 12 months apart. ESE results were compared against ANG. The study cohort comprised 47 cardiac transplant recipients. One patient's ESE images were inadequate for interpretation. Of the remaining 46 patients, ESE had a sensitivity of 88.9% (95% confidence limits [CL], 51.8%, 99.7%), a specificity of 91.9% (95% CL, 71.8%, 98.3%), and a negative predictive value of 97% (95% CL, 85.1%, 99.1%) for the ANG-detected CAD. This large, single-center study showed ESE was feasible and had a high specificity and excellent negative predictive value in excluding epicardial CAD in pediatric cardiac transplant recipients. Future prospective, large-scale studies are needed to confirm these findings and help identify a subset of children for whom a negative ESE could decrease the frequency of routine ANG.

Electrocardiographic Diagnosis of Myocardial Ischemia in Children: Is a Diagnostic Electrocardiogram Always Diagnostic?

Electrocardiographic criteria for the diagnosis of cardiac ischemia in adults are well defined; however, analogous criteria for the diagnosis of cardiac ischemia in infants and children remain ambiguous. The difficulty in defining electrocardiographic criteria in pediatrics relates to age-dependent differences in the pediatric electrocardiogram, the presence or absence of congenital heart disease, and multiple and diverse etiologies of myocardial injury that lead to an ischemic pattern on the electrocardiogram. In this report, we illustrate 3 pediatric cases in which the electrocardiogram met adult diagnostic criteria for acute transmural myocardial infarction, without coronary artery abnormalities in 2 cases and with a transient coronary abnormality in the third. In conclusion, ST-segment changes diagnostic of transmural myocardial infarction in adults may be seen in pediatric patients in the absence of coronary artery occlusion.

Subendocardial Ischemia in Adults with Repaired Coarctation: A Mechanism for Early Ischemic Events

Subendocardial Ischemia in Adults with Repaired Coarctation: A Mechanism for Early Ischemic Events

Esophageal saturation during antegrade cerebral perfusion: a preliminary report using visible light spectroscopy

Visible light spectroscopy (VLS) is newer technology that measures real-time tissue oxygenation. It has been validated in detecting mucosal ischemia in adults. During complex neonatal heart surgery, antegrade cerebral perfusion (ACP) maintains cerebral saturation. Whether ACP maintains peripheral tissue perfusion in humans is not known. Five patients undergoing neonatal open heart surgery with hypothermic cardiopulmonary bypass (CPB) were studied using a VLS esophageal probe in addition to bilateral near infrared cerebral oximetry. Three of five patients required ACP for arch repair, while two patients did not. VLS and cerebral saturation data were collected and analyzed in 5 min intervals prior to CPB, during CPB, and during ACP. In the two patients undergoing heart surgery with routine hypothermic CPB, both cerebral and esophageal saturations were maintained. However in all three neonates requiring ACP, although cerebral saturations did not decrease, esophageal saturation fell below the ischemic threshold (35%). Following establishment of normal CPB, esophageal saturation returned to baseline. Antegrade cerebral perfusion maintains cerebral oxygen delivery, however, it does not adequately perfuse the esophagus in neonates. This could have clinical implications.

Postnatal recapitulation of embryonic hedgehog pathway in response to skeletal muscle ischemia.

Hedgehog (Hh) proteins are morphogens regulating epithelial-mesenchymal signaling during several crucial processes of embryonic development, including muscle patterning. Sonic (Shh), Indian (Ihh), and Desert (Dhh) hedgehog constitute the repertoire of Hh genes in humans. The activities of all 3 are transduced via the Patched (Ptc1) receptor. Recent observations indicate that exogenous administration of Shh induces angiogenesis. Here, we studied whether the endogenous Hh pathway, in addition to its functions during embryogenesis, plays a physiological role in muscle regeneration after ischemia in adults. We found that skeletal muscle ischemia induces strong local upregulation of Shh mRNA and protein. In addition, the Ptc1 receptor is activated in interstitial mesenchymal cells within the ischemic area, indicating that these cells respond to Shh and that the Shh pathway is functional. We also found that Shh-responding cells produce vascular endothelial growth factor under ischemic conditions and that systemic treatment with a Shh-blocking antibody inhibits the local angiogenic response and the upregulation of vascular endothelial growth factor. Our study shows that the Hh signaling may be recapitulated postnatally in adult and fully differentiated muscular tissues and has a regulatory role on angiogenesis during muscle regeneration after ischemia. These findings demonstrate a novel biological activity for the Hh pathway with both fundamental and potential therapeutic implications.

Ischemia in the territory of a hypoplastic vertebrobasilar system.

Congenital variations in the configuration and size of the cerebral vessels may predispose to ischemic stroke. To illustrate that a hypoplastic basilar artery may lead to posterior circulation ischemia in adults, eight cases are reported from two university medical centers. Five men and three women with a mean age of 49.8 years are reported. Four of the patients had other conventional stroke risk factors. Two patients had brainstem strokes, and six had TIA. All patients had hypoplastic basilar arteries. Seven patients had at least one hypoplastic vertebral artery (bilateral in five cases), and six patients had both posterior cerebral arteries originating from the internal carotid arteries. A hypoplastic basilar artery is frequently accompanied by vertebral artery hypoplasia, and this can predispose adults to posterior circulation ischemia. This entity can be suspected on the basis of MR angiogram, but conventional angiography will provide definitive diagnosis. Optimal medical and surgical treatment of this condition is unresolved.

Mecanismos de muerte neuronal en la isquemia cerebral

Morphological and biochemical studies have shown an apoptotic component in neurons following either focal or global ischemia in adults, or hypoxia-ischemia during development. Different factors, including transcription factors, members of the Bcl-2 family, caspases and trophic factors, participate in the cascade of events leading to cell death. Transcription factor c-Jun is induced and expressed in the three models of ischemia as a non-specific response to the ischemic stress. The role played by the different members of the Bcl-2 family is not clear in cerebral ischemia. It is feasible that Bcl-2 expression is not sufficient to protect nerve cells from dying in those animals with physiological dotations of this protein. Yet Bcl-xS may have a role in ischemia-induced cell death following global ischemia in the adult or hypoxia-ischemia during development. Recent studies have also shown a similar putative role of caspase 1 and caspase 3 following cerebral ischemia. Finally, the ischemic insult is usually accompanied by modifications in the expression of neurotrophins and receptors. Brain-derived neurotrophic factor (BDNF) administration preserves nerve cells from dying following focal or global ischemia in adults, and hypoxia-ischemia during development. This positive effect is probably dependent on the cross-signaling between BDNF and its specific receptor TrkB. Cumulative evidence in experimental models indicates BDNF as a putative agent in the treatment of cerebral ischemia in humans.

Plasma fatty acid levels in infants and adults after myocardial ischemia

High levels of fatty acids are detrimental during reperfusion of ischemic hearts in part because of an inhibition of myocardial glucose use. We therefore measured plasma fatty acids during and after myocardial ischemia in both adult and pediatric patients. In adult patients undergoing thrombolytic therapy after an acute myocardial infarction, plasma fatty acids levels were elevated on admission to hospital (0.96 ± 0.06 vs 0.40 ± 0.01 mmol/L in healthy control subjects) and remained elevated throughout the initial 48 hours of hospitalization. In adult patients undergoing cardiac surgery, plasma fatty acids were markedly increased during surgery and at the time of the release of the aortic cross clamp (2.21 ± 0.54 and 1.61 ± 0.32 mmol/L, respectively). In children and infants (mean age 4.33 ± 0.44 years) who had surgery to correct congenital heart defects, fatty acid levels during surgery increased to 3.27 ± 0.26 mmol/L and remained elevated during immediate reperfusion (1.91 ± 0.15 mmol/L) and for 24 hours after surgery (1.67 ± 0.22 mmol/L). Because experimental studies have shown that high levels of fatty acids are detrimental to recovery of adult animal hearts, we determined the effect of high fatty acid levels on reperfusion recovery of isolated working hearts from 1-day-old rabbits perfused with 0.4 mmol/L palmitate (normal fat) or 1.2 mmol/L palmitate (high fat) and subjected to 50 minutes of global ischemia followed by aerobic reperfusion. Rabbit hearts perfused with high fat showed significantly decreased preischemic function (heart rate × change in pressure was 51.2% of normal-fat hearts) and postischemic function (heart rate × change in pressure recovered to 34.4% of values seen in normal-fat hearts). Thus the reperfused myocardium after ischemia in adults, children, and infants is exposed to elevated levels of fatty acids. In keeping with experimental data from newborn rabbits and mature animal models, it is likely that pediatric myocardial function is compromised by exposure to high fatty acid levels.

Studies of myocardial protection in the immature heart: I. Enhanced tolerance of immature versus adult myocardium to global ischemia with reference to metabolic differences

This study compares the metabolism and functional responses of adult and immature hearts to a standard ischemic insult. Ten adult dogs (25 to 27 kg) and 10 puppies (6 to 10 weeks old) underwent 45 minutes of aortic clamping on bypass. Preoperative and postoperative ventricular performance (Starling curves), biochemical factors, and water content were measured. Global ischemia in adults produced a 30% mortality rate (3/10) and low output syndrome in survivors (33% recovery of stroke work index). Conversely, all puppies survived and stroke work index returned to 85% of control, with less edema developing (0.4% versus 2% water gain, p less than 0.05). Puppies expended comparable glycogen stores but used more glutamate (15.4 versus 8.6 mumol/gm dry weight), produced more alanine (18.9 versus 6.4 mumol, p less than 0.05), succinate (19 versus 8.2 mumol, p less than 0.05), and malate (2.6 versus 0.15 mumol, p less than 0.05) during ischemia, and recovered better postischemic aerobic metabolism (410 versus 255 nmol tissue pyruvate, p less than 0.05). We conclude that tolerance of immature hearts to ischemia is related to amino acid utilization by transamination and increased substrate level phosphorylation, as occurring in diving mammals, suggesting retention of intrautero adaptive mechanisms.

Evaluation of balloon aortic valvuloplasty with transesophageal echocardiography

Percutaneous balloon valvuloplasty for the relief of congenital aortic valve stenosis in pediatric patients is being performed with increasing frequency.‘a2 Balloon valvuloplasty, however, may be complicated by cusp tear or avulsion, resulting in a worsening of aortic valve incompetence.3s4 Recognition of these adverse effects during the procedure could caution against additional dilatations with larger balloon catheters and may prevent further deterioration in aortic valve competence. Transesophageal echocardiography, which has proven to be a valuable technique for monitoring intraoperative cardiac function and myocardial ischemia in adults, would appear to be ideally suited for such a task.5 We describe the first use of transesophageal echocardiography to monitor cardiovascular changes during percutaneous balloon valvuloplasty in an adolescent with congenital aortic stenosis. A 14-year-old obese boy with congenital valvar aortic stenosis was admitted for percutaneous balloon valvuloplasty. Prior cardiac catheterization had demonstrated a 58 mm Hg peak systolic aortic valve pressure gradient and mild aortic valve incompetence. Graded exercise testing had revealed 2 mm of left precordial ST segment depression. The patient remained asymptomatic until 3 months prior to admission, when he developed angina and decreased exercise tolerance. On physical examination, the patient was obese (115 kg), with a blood pressure of 110/80 mm Hg. A prominent left ventricular impulse, precordial thrill, and grade 4/6 systolic ejection murmur were present. An early diastolic murmur was not audible. Chest roentgenography showed left ventricular prominence, while electrocardiography revealed left ventricular hypertrophy with T wave inversion in the left precordial leads. Precordial two-dimensional echocardiography was of poor quality due to the patient’s obesity. Continuous wave Doppler examination demonstrated a 120 mm Hg peak instantaneous systolic gradient and mild aortic valve incompetence. Catheterization and valvuloplasty were performed under general anesthesia. Following endotracheal intubation, a 5 MHz transesophageal echocardiography probe (Hewlett-Packard Co., Andover, Mass.) capable