Pre-stimulus theta power is correlated with variation of motor evoked potential latency: a single-pulse TMS study.

There has been a growing interest in the role of pre-stimulus oscillations on cortical excitability in visual and motor systems. Prior studies focused on the relationship between pre-stimulus neuronal activity and TMS-evoked motor evoked potentials (MEPs) have reported heterogeneous results. We aimed to assess the role of pre-stimulus neural activity on the latency of MEPs, which might enhance our understanding of the variability of MEP signals, and potentially provide information on the role played by cortical activity fluctuations in the excitability of corticospinal pathways. Near-threshold single-pulse TMS (spTMS) was applied at random intervals over the primary motor cortex of 14 healthy participants while they sat passively, to trigger hand muscle contractions. Multichannel EEG was recorded during spTMS blocks. Spearman correlations between both the variation in MEP onset latencies and peak-to-peak MEP amplitudes, and the pre-stimulus power of EEG oscillations were calculated across participants. We found that the variation in MEP latency was positively correlated with pre-stimulus power in the theta range (4-7 Hz) in a broad time window (- 3.1 to - 1.9 s) preceding the spTMS generating the MEP. No correlation between pre-stimulus power in any frequency band and MEP amplitude was found. Our results show that pre-stimulus theta oscillations are correlated with the variation in MEP latency, an outcome measure determined by fiber conduction velocity and synaptic delays along the corticospinal tract. This finding could prove useful for clinicians using MEP latency-based information in pre- or intra-operative diagnostics of corticospinal impairment.

Aneurysm rupture from blunt abdominal trauma after endovascular repair.

We present a case of aneurysm rupture from severe blunt abdominal trauma due to fight in a patient who had endovascular aneurysm repair. The patient presented to the emergency service with computed tomography evidence of an endoleak and a large retroperitoneal hematoma. The contrast abdominal computed tomography demonstrated a type Ib endoleak, increase in the aneurysm diameter and hematoma in the retroperitoneum. The patient has been taken under interventional procedure for endovascular aneurysm repair revision under urgent condition. Type Ib endoleak was treated by placement of a covered iliac extension limb, but a second leakage from graft body was found in control computed tomography images and open surgical conversion was necessary. Operative findings included a type III endoleak from graft body, defect on fabric. It was seen that the aneurysm sac anterior and posterior parts were ruptured. Upon reviewing the literature, we found that it was an interesting case as the first rupture case which had been developed after severe blunt abdominal trauma during the follow-up period of a patient on which endovascular aneurysm repair procedure had been performed and progressed in this manner.

Test-retest reliability of freesurfer measurements within and between sites: Effects of visual approval process.

In the last decade, many studies have used automated processes to analyze magnetic resonance imaging (MRI) data such as cortical thickness, which is one indicator of neuronal health. Due to the convenience of image processing software (e.g., FreeSurfer), standard practice is to rely on automated results without performing visual inspection of intermediate processing. In this work, structural MRIs of 40 healthy controls who were scanned twice were used to determine the test-retest reliability of FreeSurfer-derived cortical measures in four groups of subjects-those 25 that passed visual inspection (approved), those 15 that failed visual inspection (disapproved), a combined group, and a subset of 10 subjects (Travel) whose test and retest scans occurred at different sites. Test-retest correlation (TRC), intraclass correlation coefficient (ICC), and percent difference (PD) were used to measure the reliability in the Destrieux and Desikan-Killiany (DK) atlases. In the approved subjects, reliability of cortical thickness/surface area/volume (DK atlas only) were: TRC (0.82/0.88/0.88), ICC (0.81/0.87/0.88), PD (0.86/1.19/1.39), which represent a significant improvement over these measures when disapproved subjects are included. Travel subjects' results show that cortical thickness reliability is more sensitive to site differences than the cortical surface area and volume. To determine the effect of visual inspection on sample size required for studies of MRI-derived cortical thickness, the number of subjects required to show group differences was calculated. Significant differences observed across imaging sites, between visually approved/disapproved subjects, and across regions with different sizes suggest that these measures should be used with caution.

Steady state visual evoked potential (SSVEP) based brain-computer interface (BCI) performance under different perturbations.

Brain-computer interface (BCI) paradigms are usually tested when environmental and biological artifacts are intentionally avoided. In this study, we deliberately introduced different perturbations in order to test the robustness of a steady state visual evoked potential (SSVEP) based BCI. Specifically we investigated to what extent a drop in performance is related to the degraded quality of EEG signals or rather due to increased cognitive load. In the online tasks, subjects focused on one of the four circles and gave feedback on the correctness of the classification under four conditions randomized across subjects: Control (no perturbation), Speaking (counting loudly and repeatedly from one to ten), Thinking (mentally counting repeatedly from one to ten), and Listening (listening to verbal counting from one to ten). Decision tree, Naïve Bayes and K-Nearest Neighbor classifiers were used to evaluate the classification performance using features generated by canonical correlation analysis. During the online condition, Speaking and Thinking decreased moderately the mean classification accuracy compared to Control condition whereas there was no significant difference between Listening and Control conditions across subjects. The performances were sensitive to the classification method and to the perturbation conditions. We have not observed significant artifacts in EEG during perturbations in the frequency range of interest except in theta band. Therefore we concluded that the drop in the performance is likely to have a cognitive origin. During the Listening condition relative alpha power in a broad area including central and temporal regions primarily over the left hemisphere correlated negatively with the performance thus most likely indicating active suppression of the distracting presentation of the playback. This is the first study that systematically evaluates the effects of natural artifacts (i.e. mental, verbal and audio perturbations) on SSVEP-based BCIs. The results can be used to improve individual classification performance taking into account effects of perturbations.

What to expect after tricuspid valve replacement? Long-term results.

OBJECTIVE: Current knowledge in long-term results of tricuspid valve replacement is limited. Present study reviews our experience from a consecutive series. METHODS: Forty-two patients (16 male, 26 female; mean age: 33+/-15) underwent tricuspid valve replacement between March 1987 and December 2004. The etiology was rheumatic in 64%, Ebstein's anomaly in 31%, and endocarditis in 5%. Nineteen patients were in New York Heart Association (NYHA) Class III functional capacity (45%), and 13 in class IV (31%). Twenty patients (48%) underwent isolated tricuspid valve replacement. The remaining underwent combined (mitral and/or aortic) valve replacements. Tricuspid replacement device was mechanical in 31% and bioimplant in 69%. RESULTS: Hospital mortality was 26%. Rheumatic etiology, reoperation and elevated pulmonary artery pressure were associated with higher early mortality. The patients with decreased functional capacity (NYHA Class III/IV), congestive symptoms and rheumatic origin were more prone to low cardiac output development. The Kaplan-Meier survivals were 37% at 10 years and 30% at 15 years. The 10-year event-free survival was 31%. Elevated pulmonary artery pressure and rheumatic etiology unfavorably affected the long-term results. The average functional capacity in survivors improved significantly after operation. CONCLUSIONS: Any tricuspid disease not amenable to repair thus necessitating replacement is an unfortunate situation since both the short and long-term results of valve replacement are suboptimal in regard to those of left-sided valve replacements, probably due to different structural and geometrical characteristics of right ventricle and the low-pressure venous system hemodynamics. Etiology, clinical presentation and pulmonary vascular hemodynamics are major determinants of the outcome.

A positron emission tomography study of the serotonergic system in relation to anxiety in depression.

Symptoms of anxiety are highly comorbid with major depressive disorder (MDD) and are known to alter the course of the disease. To help elucidate the biological underpinnings of these prevalent disorders, we previously examined the relationship between components of anxiety (somatic, psychic and motoric) and serotonin 1A receptor (5-HT1A) binding in MDD and found that higher psychic and lower somatic anxiety was associated with greater 5-HT1A binding. In this work, we sought to examine the correlation between these anxiety symptom dimensions and 5-HTT binding. Positron emission tomography with [11C]-3-amino-4-(3-dimethylamino-methylphenylsulfanyl)-benzonitrile ([11C]DASB) and a metabolite-corrected arterial input function were used to estimate regional 5-HTT binding in 55 subjects with MDD and anxiety symptoms. Somatic anxiety was negatively correlated with 5-HTT binding in the thalamus (ß=-.33, p=.025), amygdala (ß=-.31, p=.007) and midbrain (ß=-.72, p<.001). Psychic anxiety was positively correlated with 5-HTT binding in midbrain only (ß=.46, p=.0025). To relate to our previous study, correlation between 5-HT1A and 5-HTT binding was examined, and none was found. We also examined how much of the variance in anxiety symptom dimensions could be explained by both 5-HTT and 5-HT1A binding. The developed model was able to explain 68% (p<.001), 38% (p=.012) and 32% (p=.038) of the total variance in somatic, psychic, and motoric anxiety, respectively. Results indicate the tight coupling between the serotonergic system and anxiety components, which may be confounded when using aggregate anxiety measures. Uncovering serotonin's role in anxiety and depression in this way may give way to a new generation of therapeutics and treatment strategies.

Cardiac surgery during pregnancy.

BACKGROUND AND AIM OF THE STUDY: Cardiac surgery during pregnancy represents a major challenge as it comprises a single operation for two survivors. METHODS: Between 1988 and 2005, 16 pregnant women underwent cardiac surgery at the authors' institution. Among 14 patients with rheumatic mitral stenosis operated on due to clinical deterioration, closed mitral valvulotomy was performed in 12 cases (three urgently in the third trimester, nine at term concomitantly with cesarean delivery). Two patients underwent mitral valve replacement, again, concomitantly with cesarean delivery at term, while two others underwent emergency reoperation for mechanical valve thrombosis during the second trimester, using a strategy of high-flow, high-pressure perfusion with mild hypothermia. RESULTS: A total of 12 closed mitral valvulotomies and four mitral valve replacements was performed. There was no maternal mortality, and only one stillborn occurred in the urgent closed valvulotomy group. The remaining 15 babies were born healthy. CONCLUSION: In addition to protective perinatal procedures, instances occur during pregnancy when urgent or emergency surgery becomes unavoidable due to life-threatening cardiac decompensation. In patients with mitral stenosis, which is the case in most scenarios, closed mitral valvulotomy is life-saving and offers low fetomaternal risk, as a viable, efficient and practical alternative to percutaneous mitral balloon commissurotomy. When cardiopulmonary bypass (CPB) becomes mandatory, the shortest possible periods of mildly hypothermic or normothermic CPB with a strategy of high flow-high pressure perfusion should be followed.

Pre-stimulus Alpha Oscillations and Inter-subject Variability of Motor Evoked Potentials in Single- and Paired-Pulse TMS Paradigms.

Inter- and intra-subject variability of the motor evoked potentials (MEPs) to TMS is a well-known phenomenon. Although a possible link between this variability and ongoing brain oscillations was demonstrated, the results of the studies are not consistent with each other. Exploring this topic further is important since the modulation of MEPs provides unique possibility to relate oscillatory cortical phenomena to the state of the motor cortex probed with TMS. Given that alpha oscillations were shown to reflect cortical excitability, we hypothesized that their power and variability might explain the modulation of subject-specific MEPs to single- and paired-pulse TMS (spTMS, ppTMS, respectively). Neuronal activity was recorded with multichannel electroencephalogram. We used spTMS and two ppTMS conditions: intracortical facilitation (ICF) and short-interval intracortical inhibition (SICI). Spearman correlations were calculated within and across subjects between MEPs and the pre-stimulus power of alpha oscillations in low (8-10 Hz) and high (10-12 Hz) frequency bands. Coefficient of quartile variation was used to measure variability. Across-subject analysis revealed no difference in the pre-stimulus alpha power among the TMS conditions. However, the variability of high-alpha power in spTMS condition was larger than in the SICI condition. In ICF condition pre-stimulus high-alpha power variability correlated positively with MEP amplitude variability. No correlation has been observed between the pre-stimulus alpha power and MEP responses in any of the conditions. Our results show that the variability of the alpha oscillations can be more predictive of TMS effects than the commonly used power of oscillations and we provide further support for the dissociation of high and low-alpha bands in predicting responses produced by the stimulation of the motor cortex.

Long-Range Temporal Correlations in the amplitude of alpha oscillations predict and reflect strength of intracortical facilitation: Combined TMS and EEG study.

While variability of the motor responses to transcranial magnetic stimulation (TMS) is widely acknowledged, little is known about its central origin. One plausible explanation for such variability may relate to different neuronal states defining the reactivity of the cortex to TMS. In this study intrinsic spatio-temporal neuronal dynamics were estimated with Long-Range Temporal Correlations (LRTC) in order to predict the inter-individual differences in the strength of intra-cortical facilitation (ICF) and short-interval intracortical inhibition (SICI) produced by paired-pulse TMS (ppTMS) of the left primary motor cortex. LRTC in the alpha frequency range were assessed from multichannel electroencephalography (EEG) obtained at rest before and after the application of and single-pulse TMS (spTMS) and ppTMS protocols. For the EEG session, preceding TMS application, we showed a positive correlation across subjects between the strength of ICF and LRTC in the fronto-central and parietal areas. This in turn attests to the existence of subject-specific neuronal phenotypes defining the reactivity of the brain to ppTMS. In addition, we also showed that ICF was associated with the changes in neuronal dynamics in the EEG session after the application of the stimulation. This result provides a complementary evidence for the recent findings demonstrating that the cortical stimulation with sparse non-regular stimuli might have considerable long-lasting effects on the cortical activity.

Risk Factors for Survival following Open Surgical Repair of Ruptured Abdominal Aortic Aneurysms: A 13-Year Experience.

BACKGROUND: Surgical treatment of a ruptured abdominal aorta aneurysm (RAAA) continues to present a significant challenge to surgeons. There are some patient factors such as age and gender that cannot be changed, and comorbid conditions can be optimized but not eliminated. The purpose of this study was to identify the risk factors affecting high mortality after the surgical repair of an RAAA. METHODS: Data on 121 patients who underwent surgical repair for RAAAs between January 1997 and June 2011 in our institution were collected retrospectively. All the patients had been diagnosed by computed tomography (CT) scans, and intraoperative extra-luminal blood was visualized intraoperatively. Variables studied comprised demographic data; preoperative, operative, and postoperative data; and the causes of mortality. Multivariate regression analysis was used to determine the predictors of mortality. RESULTS: One hundred eight (89.2%) patients were male and 13 (10.7%) were female at an average age of 68.9 ± 10.5 years. Totally, 121 patients underwent surgery for RAAAs. Fifty-four patients had aortic tube grafts, 32 aortobiiliac grafts, 20 aortobifemoral grafts, 1 aortoiliac graft, and 1 aortofemoral graft for the replacement of the RAAAs. Seven patients had only surgical exploration. Operative mortality was 41.3% (50 patients). The factors associated with mortality were preoperative shock, free blood, positive inotropic agent, hematocrit value, and need for blood and plasma. In the multivariate analysis, preoperative shock and positive inotropic agents were found to be significant as the predictors of death (OR: 19.8, 95%CI: 3.2-122.8 and OR: 8.6, 95% CI: 2.9-26.3, respectively). CONCLUSION: This study revealed that the preoperative clinical findings affected the mortality associated with RAAAs.

[The efficiency of fast track protocol in elderly patients who underwent coronary artery surgery]. / Koroner arter cerrahisi uygulanan yasli hastalarda "fast track" protokolünün etkinligi.

OBJECTIVE: This study is planned to display the efficiency of fast track protocol and its difference from the conventional anesthesia in patients older than 65 years. METHODS: One hundred patients older than 65 years underwent coronary artery surgery between October 2000-March 2001 in cardiovascular surgery clinic were considered in this study. Fifty patients in whom fast track protocol was applied were included into the study group, group A; fifty patients underwent conventional anesthesia technique were referred to the control group, group B. In both groups demographic characteristics, early hospital mortality, operation time, total drainage, number of transfusions, stay in the intensive care unit and discharge time were recorded. RESULTS: The mean age was 69.0+/-3.0 years in group A and 70.4+/-3.6 years in group B. Early hospital mortality was 2% in group A, 10% in group B (p>0.05). Intensive care unit stay was 22.01+/-10.12 hours in group A and 60.18+/-32.23 hours in group B (p<0.05). Discharge time was on 5.5+/-1.3 day in group A and on 6.9+/-2.3 day in group B (p<0.05). There were no statistical differences between the two groups in respect to other parameters. CONCLUSION: Fast track protocol in patients older than 65 years is a suitable technique by using modern cardiac surgery methods. This protocol is successfully used by selecting the suitable patients and following the patients carefully in the postoperative period.

Compelling nature of arterial manifestations in Behcet disease.

INTRODUCTION: We present our experience with surgical treatment of arterial complications in Behcet disease (vasculo-Behcet disease), and the long-term results and pitfalls of surgical treatment. MATERIAL AND METHODS: Between January 1990 and January 2003, 20 consecutive patients underwent surgery to treat vasculo-Behcet disease. Most patients (17 of 20) were men, with mean age of 38.4 years. RESULTS: Thirty-four operations were performed in 20 patients. The operative mortality rate was 5.8% (2 patients). There were 17 emergency operations, 6 because of ruptured primary abdominal aneurysms. There were five others with critical limb ischemia, resulting in 3 amputations. All patients were followed up postoperatively on average for 44 months (range, 6 months-14 years). Two additional patients were lost to follow-up. After the initial operation 10-year survival rate was 30%, 10-year complication-free survival rate was 13%, and 5-year repeat operation-free survival rate was 26%. CONCLUSION: Although surgical intervention should be postponed until active inflammation has subsided, often this is not possible, because of the emergent nature of these problems. Most arterial complications of vasculo-Behcet disease present with a pseudoaneurysm rupture or with impending rupture. An aggressive surgical approach can be life-saving in such instances, and should be undertaken regardless of long-term complications, which are more common when the operation is performed in the presence of active inflammation. Early and late results can be improved by individualizing, selecting a disease-free area for reconstruction, and eliminating use of autologous graft material.

Off-pump, in situ internal thoracic artery grafting: a durable treatment for single-vessel coronary artery disease.

BACKGROUND: The value of off-pump in situ left internal thoracic artery to left anterior descending coronary artery bypass grafting in single-vessel coronary artery disease was assessed by long-term angiographic and clinical data. METHODS: One-hundred three randomly selected patients (87 male, 16 female; mean age, 57.4 +/- 10.5 years) underwent postoperative angiographic control after an average postoperative period of 4.8 +/- 2.9 years (up to 8.2 years; a total of 490 patient-years). RESULTS: Fifty-five patients (52%) were asymptomatic, whereas 31 (30%) had anginalike chest pain. Ninety-seven patients (94.2%) were in New York Heart Association class I or II. Five-year angina-free survival was 81% +/- 5%. Of 103 left internal thoracic arteries assessed, 99 were patent (overall patency, 96.1%). All four cases having occluded grafts had mild native vessel stenoses (<80%) before operation. The patency rate was 99% +/- 1% at 3 years, and 93% +/- 4% at 5 years. The left ventricular segmental wall motion score of the left anterior descending coronary arterial distribution improved from 4.1 +/- 1.1 to 3.7 +/- 0.9 (p = 0.001). Consequently, 15 patients (15%) underwent secondary revascularization (11 interventional and 4 surgical) 4.8 +/- 2.1 years after the primary operation. The most frequent indication for interventional revascularization was atherosclerotic progression in systems other than left anterior descending artery. The cases with graft occlusion were treated surgically. Five-year freedom from interventional or surgical repeat revascularization was 91% +/- 4%. CONCLUSIONS: In addition to the well-documented safety and reliability, off-pump in situ left internal thoracic artery grafting is also a durable treatment for isolated left anterior descending artery disease, in both clinical and angiographic terms.

Off-pump coronary artery bypass grafting: long term angiographic results.

OBJECTIVE: Although short-term results of off-pump coronary artery bypass grafting are well documented, late postoperative data are still scarce. This report provides an analysis of late postoperative control angiograms. METHODS: 265 patients (231 males, 34 females; mean age: 54 +/- 10) underwent postoperative angiographic control, after an average postoperative period of 4.2 +/- 2.3 years (up to 9 years, a total of 1110 years). A total of 385 distal anastomoses on 258 internal mammary arteries (IMAs) and 127 saphenous vein grafts (SVGs) were evaluated. The primary operation was single bypass in 156 cases (62%), double bypass in 98 (34%), and triple or more bypass in 11 (4%). RESULTS: Out of 258 IMAs, 241 were patent (93%), while SVG patency was 65% with 82 patent grafts out of 127 (p < 0.0001). The patency in the lateral branches (62%) and right coronary system (64%) were similar. The variables associated with graft occlusion were hypercholesterolemia (p = 0.02), poor left ventricular performance (p = 0.03), reoperation (p = 0.01), target coronary vessel caliber less than 1.5 mm (p < 0.0001), poor native coronary vessel quality (p = 0.0003) and low-grade stenosis (p = 0.02). In the poor left ventricle group, the left ventricular segmental wall motion score was improved (p = 0.004). Consequently, 47 patients underwent secondary revascularization (35 PTCA and 12 CABG). The leading indication was native coronary artery disease progression, frequently in the circumflex system, followed by graft failure. The cases with native vessel disease progression were referred to PTCA/stenting, while those with LAD graft occlusion were treated surgically. CONCLUSIONS: Probably the best candidates for OPCAB are those having target vessels of good caliber and quality, and high-grade stenoses. Postoperative lipid-lowering therapy seems to be prudential.

Does diltiazem inhibit the inflammatory response in cardiopulmonary bypass?

BACKGROUND: The objective of our study was to investigate the anti-inflammatory effect and inhibiting action of diltiazem, a calcium channel blocking agent, on the systemic inflammatory response seen after cardiopulmonary bypass (CPB) in humans, in a controlled prospective study. MATERIAL/METHODS: Two groups of 15 candidates for coronary artery bypass graft were enrolled in the study. In the study group, 1 g/kg/min of diltiazem was infused during cardiopulmonary bypass, while the control group received saline. Interleukin-6 and 10 (IL-6, IL-10) levels were measured from systemic arterial blood at five time points. RESULTS: The levels of IL-6, a marker of the severity of systemic inflammation, were significantly higher in the control group at the end of CPB and 3 hours later. At the end of CPB, the mean IL-6 level in the control group was significantly higher than in the diltiazem group (p=0.015), and at 3 hours after CPB the difference was even greater (p=0.002). The levels of IL-10, an anti-inflammatory cytokine that limits the effects of pro-inflammatory cytokines, were higher in the control group, but not statistically significant at any time point. CONCLUSIONS: Diltiazem inhibits the release of the pro-inflammatory cytokine IL-6, which is strong evidence for its anti-inflammatory effect. It is clinically important to inhibit the inflammation that takes place during CPB and the inflammation of myocardium encountered after ischemia-reperfusion, since these effect the clinical status of the patient after CPB, as well as myocardial functions.

Coronary artery anomalies in adult patients.

BACKGROUND: Coronary artery anomalies are discovered in less than 1% of angiography series. Since the number of angiographies and coronary bypass operations are increasing significantly every day, these anomalies are of clinical importance. MATERIAL/METHODS: 58,023 coronary angiographies were performed in the cardiology clinic of our hospital from 1978 to 2001. Coronary artery anomalies were discovered in 257 of these cases (0.44%). The mean age of these patients was 51.9+/-11.4 years (18-82). 80% were male (n=207). RESULTS: The circumflex artery (CXA) was the most frequently involved vessel (51.1%). Coronary arteries originating from the pulmonary artery were not encountered in our series due to the natural history of the disease. In 54 patients with coronary artery fistulae, 18 (33.3%) were closed by operation. Perioperative mortality was 5.5%. Acquired coronary artery fistulae or aneurysms due to trauma or inflammatory diseases are completely different entities and beyond the scope of this article. In 76 patients, open heart surgery was required for additional lesions, 57 of which were coronary artery bypass grafts. CONCLUSIONS: Being usually asymptomatic, coronary artery anomalies are usually discovered incidentally in the adult population. These pathologies are important for practical purposes, especially for interventional cardiologists, radiologists and cardiac surgeons, who should be aware of these anatomical entities. LMCA originating from the right coronary system has been reported to result in sudden death and myocardial ischemia, so these mostly asymptomatic patients must be followed closely.