Cause or effect of arteriogenesis: compositional alterations of microparticles from CAD patients undergoing external counterpulsation therapy

Recently, a clinical study on patients with stable coronary artery disease (CAD) showed that external counterpulsation therapy (ECP) at high (300 mmHg) but not at low inflation pressure (80 mmHg) promoted coronary collateral growth, most likely due to shear stress-induced arteriogenesis. The exact molecular mechanisms behind shear stress-induced arteriogenesis are still obscure. We therefore characterized plasma levels of circulating microparticles (MPs) from these CAD patients because of their ambivalent nature as a known cardiovascular risk factor and as a promoter of neovascularization in the case of platelet-derived MPs. MPs positive for Annexin V and CD31CD41 were increased, albeit statistically significant (P<0.05, vs. baseline) only in patients receiving high inflation pressure ECP as determined by flow cytometry. MPs positive for CD62E, CD146, and CD14 were unaffected. In high, but not in low, inflation pressure treatment, change of CD31CD41 was inversely correlated to the change in collateral flow index (CFI), a measure for collateral growth. MPs from the high inflation pressure group had a more sustained pro-angiogenic effect than the ones from the low inflation pressure group, with the exception of one patient showing also an increased CFI after treatment. A total of 1005 proteins were identified by a label-free proteomics approach from MPs of three patients of each group applying stringent acceptance criteria. Based on semi-quantitative protein abundance measurements, MPs after ECP therapy contained more cellular proteins and increased CD31, corroborating the increase in MPs. Furthermore, we show that MP-associated factors of the innate immune system were decreased, many membrane-associated signaling proteins, and the known arteriogenesis stimulating protein transforming growth factor beta-1 were increased after ECP therapy. In conclusion, our data show that ECP therapy increases platelet-derived MPs in patients with CAD and that the change in protein cargo of MPs is likely in favor of a pro angiogenic/arteriogenic property.

Determinants of prognostically relevant intracoronary electrocardiogram ST-segment shift during coronary balloon occlusion

The prognostic relevance of quantitative an intracoronary occlusive electrocardiographic (ECG) ST-segment shift and its determinants have not been investigated in humans. In 765 patients with chronic stable coronary artery disease, the following simultaneous quantitative measurements were obtained during a 1-minute coronary balloon occlusion: intracoronary ECG ST-segment shift (recorded by angioplasty guidewire), mean aortic pressure, mean distal coronary pressure, and mean central venous pressure (CVP). Collateral flow index (CFI) was calculated as follows: (mean distal coronary pressure minus CVP)/(mean aortic pressure minus CVP). During an average follow-up duration of 50 ± 34 months, the cumulative mortality rate from all causes was significantly lower in the group with an ST-segment shift <0.1 mV (n = 89) than in the group with an ST-segment shift ≥0.1 mV (n = 676, p = 0.0211). Factors independently related to intracoronary occlusive ECG ST-segment shift <0.1 mV (r(2) = 0.189, p <0.0001) were high CFI (p <0.0001), intracoronary occlusive RR interval (p = 0.0467), right coronary artery as the ischemic region (p <0.0001), and absence of arterial hypertension (p = 0.0132). "High" CFI according to receiver operating characteristics analysis was ≥0.217 (area under receiver operating characteristics curve 0.647, p <0.0001). In conclusion, absence of ECG ST-segment shift during brief coronary occlusion in patients with chronic coronary artery disease conveys a decreased mortality and is directly influenced by a well-developed collateral supply to the right versus left coronary ischemic region and by the absence of systemic hypertension in a patient's history.

Coronary collaterals and risk for restenosis after percutaneous coronary interventions: a meta-analysis

The benefit of the coronary collateral circulation (natural bypass network) on survival is well established. However, data derived from smaller studies indicates that coronary collaterals may increase the risk for restenosis after percutaneous coronary interventions. The purpose of this systematic review and meta-analysis of observational studies was to explore the impact of the collateral circulation on the risk for restenosis.

Variable ECG signs of ischemia during controlled occlusion of the left and right coronary artery in humans

Infarct size (IS) increases with vascular occlusion time, area at risk for infarction, lack of collateral supply, absence of preconditioning, and myocardial demand for O2 supply. ECG S-T segment elevation is used as a measure of severity of ischemia and a surrogate for IS. This study in 50 patients with coronary artery disease undergoing a first 120-s balloon occlusion of a stenosis sought to determine whether S-T segment elevation, corrected for the above-mentioned variables, in the left coronary artery (LCA group, n = 36) is different from that in the right coronary artery (RCA group, n = 14) territory. After consideration of all known determinants of IS, particularly mass at risk and collateral supply, the LCA territory is more sensitive than the RCA region to a 2-min period of myocardial ischemia.

Ligament balancing in TKA: Evaluation of a force-sensing device and the influence of patellar eversion and ligament release

Ligament balancing in total knee arthroplasty may have an important influence on joint stability and prosthesis lifetime. In order to provide quantitative information and assistance during ligament balancing, a device that intraoperatively measures knee joint forces and moments was developed. Its performance and surgical advantages were evaluated on six cadaver specimens mounted on a knee joint loading apparatus allowing unconstrained knee motion as well as compression and varus-valgus loading. Four different experiments were performed on each specimen. (1) Knee joints were axially loaded. Comparison between applied and measured compressive forces demonstrated the accuracy and reliability of in situ measurements (1.8N). (2) Assessment of knee stability based on condyle contact forces or varus-valgus moments were compared to the current surgical method (difference of varus-valgus loads causing condyle lift-off). The force-based approach was equivalent to the surgical method while the moment-based, which is considered optimal, showed a tendency of lateral imbalance. (3) To estimate the importance of keeping the patella in its anatomical position during imbalance assessment, the effect of patellar eversion on the mediolateral distribution of tibiofemoral contact forces was measured. One fourth of the contact force induced by the patellar load was shifted to the lateral compartment. (4) The effect of minor and major medial collateral ligament releases was biomechanically quantified. On average, the medial contact force was reduced by 20% and 46%, respectively. Large variation among specimens reflected the difficulty of ligament release and the need for intraoperative force monitoring. This series of experiments thus demonstrated the device's potential to improve ligament balancing and survivorship of total knee arthroplasty.

New concept for CTO recanalization using controlled antegrade and retrograde subintimal tracking: the CART technique

OBJECTIVES: To demonstrate the safety and feasibility of a new concept for CTO recanalization using a controlled antegrade and retrograde subintimal tracking technique (CART technique). BACKGROUND: A successful percutaneous recanalization of chronic coronary occlusions results in improved survival, as well as enhanced left ventricular function, reduction in angina, and improved exercise tolerance. However, successful recanalization of CTOs is still not optimal, and needs further improvements. METHODS: Ten patients with a CTO underwent the CART procedure. This technique combines the simultaneous use of the antegrade and retrograde approaches. A subintimal dissection is created antegradely and retrogradely, which allows the operator to limit the extension of the subintimal dissection in the CTO portion. A retrograde approach means that the occlusion site is approached in a retrograde fashion through the best collateral channel from any other patent coronary artery. RESULTS: The occlusion site was located in the RCA in 9 patients, and in the LAD in 1 patient. CTO duration varied from 7 to 84 months. Vessel recanalization was achieved in all patients. In all cases, the subintimal dissection was limited to the CTO region. No complications occurred in the collateral channel used for the retrograde approach. There were no in-hospital major adverse cardiac events. CONCLUSIONS: The CART technique is feasible, safe, and has a high success rate.

Does the beta-blocker nebivolol increase coronary flow reserve?

INTRODUCTION: Nebivolol, a highly selective beta1-adrenergic receptor-blocker, increases basal and stimulated endothelial nitric oxide (NO)-release. It is unknown, whether coronary perfusion is improved by the increase in NO availability. Therefore, we sought to evaluate the effect of nebivolol on coronary flow reserve (CFR) and collateral flow. METHODS: Doppler-flow wire derived coronary flow velocity measurements were obtained in ten controls and eight patients with coronary artery disease (CAD) at rest and after intracoronary nebivolol. CFR was defined as maximal flow during adenosine-induced hyperemia divided by resting flow. In the CAD group, collateral flow was determined after dilatation of a flow-limiting coronary stenosis. Collateral flow index (CFI) was defined as the ratio of flow velocity during balloon inflation divided by resting flow. RESULTS: CFR at rest was 3.0+/-0.6 in controls and 2.1+/-0.4 in CAD patients. After intracoronary doses of 0.1, 0.25, and 0.5 mg nebivolol, CFR increased to 3.4+/-0.7, 3.9+/-0.9, and 4.0+/-0.1 (p<0.01) in controls, and to 2.3+/-0.7, 2.6+/-0.9, and 2.6+/-0.5 (p<0.05) in CAD patients. CFI decreased significantly with intracoronary nebivolol and correlated to changes in heart rate (r=0.75, p<0.001) and rate-pressure product (r=0.59, p=0.001). DISCUSSION: Intracoronary nebivolol is associated with a significant increase in CFR due to reduction in resting flow (controls), or due to an increase in maximal coronary flow (CAD patients). CFI decreased with nebivolol parallel to the reduction in myocardial oxygen consumption.

Multi-vessel stenting during primary percutaneous coronary intervention for acute myocardial infarction. A single-center experience

BACKGROUND: Recanalization of the culprit lesion is the main goal of primary angioplasty for acute ST-segment elevation myocardial infarction (STEMI). Patients presenting with acute myocardial infarction and multivessel disease are, therefore, usually subjected to staged procedures, with the primary percutaneous coronary intervention (PCI) confined to recanalization of the infarct-related artery (IRA). Theoretically at least, early relief of stenoses of non-infarct-related arteries could promote collateral circulation, which could help to limit the infarct size. However, the safety and feasibility of such an approach has not been adequately established. METHODS: In this single-center prospective study we examined 73 consecutive patients who had an acute STEMI and at least one or more lesions > or = 70% in a major epicardial vessel other than the infarct-related artery. In the first 28 patients, forming the multi-vessel (MV) PCI group, all lesions were treated during the primary procedure. In the following 45 patients, forming the culprit-only (CO) PCI group, only the culprit lesion was treated during the initial procedure, followed by either planned-staged or ischemia-driven revascularization of the non-culprit lesions. Fluoroscopy time and contrast dye amount were compared between both groups, and patients were followed up for one year for major adverse cardiac events (MACE) and other significant clinical events. RESULTS: The two groups were well balanced in terms of clinical characteristics, number of diseased vessels and angiographic characteristics of the culprit lesion. In the MV-PCI group, 2.51 lesions per patient were treated using 2.96 +/- 1.34 stents (1.00 lesions and 1.76 +/- 1.17 stents in the CO-PCI group, both p < 0.001). The fluoroscopy time increased from 10.3 (7.2-16.9) min in the CO-PCI group to 12.5 (8.5-19.3) min in the MV-PCI group (p = 0.22), and the amount of contrast used from 200 (180-250) ml to 250 (200-300) ml, respectively (p = 0.16). Peak CK and CK-MB were significantly lower in patients of the MV-PCI group (843 +/- 845 and 135 +/- 125 vs 1652 +/- 1550 and 207 +/- 155 U/l, p < 0.001 and 0.01, respectively). Similar rates of major adverse cardiac events at one year were observed in the two groups (24% and 28% in multi-vessel and culprit treatment groups, p = 0.73). The incidence of new revascularization in both infarct- and non-infarct-related arteries was also similar (24% and 28%, respectively, p = 0.73). CONCLUSION: We may state from this limited experience that a multi-vessel stenting approach for patients with acute STEMI and multi-vessel disease is feasible and probably safe during routine clinical practice. Our data suggest that this approach may help to limit the infarct size. However, larger studies, perhaps using drug-eluting stents, are still needed to further evaluate the safety and efficiency of this procedure, and whether it is associated with a lower need of subsequent revascularization and lower costs.

Strangulation signs: initial correlation of MRI, MSCT, and forensic neck findings

PURPOSE: To evaluate multislice spiral computed tomography (MSCT) and magnetic resonance imaging (MRI) findings in hanging and manual strangulation cases and compare them with forensic autopsy results. MATERIALS AND METHODS: Postmortem MSCT and MRI of nine persons who died from hanging or manual strangulation were performed. The neck findings were compared with those discovered during forensic autopsy. In addition, two living patients underwent imaging and clinical examination following severe manual strangulation and near-hanging, respectively. For evaluation, the findings were divided into "primary" (strangulation mark and subcutaneous desiccation (i.e., soft-tissue thinning as a result of tissue fluids being driven out by mechanical compression) in hanging, and subcutaneous and intramuscular hemorrhage in manual strangulation) and "collateral" signs. The Wilcoxon two-tailed test was used for statistical analysis of the lymph node and salivary gland findings. RESULTS: In hanging, the primary and most frequent collateral signs were revealed by imaging. In manual strangulation, the primary findings were accurately depicted, with the exception of one slight hemorrhage. Apart from a vocal cord hemorrhage, all frequent collateral signs could be diagnosed radiologically. Traumatic lymph node hemorrhage (P = 0.031) was found in all of the manual strangulation cases. CONCLUSION: MSCT and MRI revealed strangulation signs concordantly with forensic pathology findings. Imaging offers a great potential for the forensic examination of lesions due to strangulation in both clinical and postmortem settings.

Leg ischemia: assessment with MR angiography and spectroscopy

PURPOSE: To prospectively determine reproducibility of magnetic resonance (MR) angiography and MR spectroscopy of deoxymyoglobin in assessment of collateral vessels and tissue perfusion in patients with critical limb ischemia (CLI) and to follow changes in patients undergoing intramuscular vascular endothelial growth factor (pVEGF)-C gene therapy, percutaneous transluminal angioplasty, supervised exercise training, or no therapy. MATERIALS AND METHODS: Study and gene therapy protocols were approved, and all patients gave written informed consent. To determine repeatability and reproducibility, seven patients underwent MR angiography and five underwent MR spectroscopy. The techniques were used to judge disease progress in 12 other patients with or without therapy: MR angiography to help determine change in visualization of collateral vessels and MR spectroscopy to help assess change in perfusion at proximal and distal calf levels. MR angiographic results were subjectively analyzed by three blinded readers. Intraobserver variability was expressed as 95% confidence interval (CI) (n=7); interobserver variability, as kappa statistic (n=15). Reexamination variability of MR spectroscopy was given as 95% CI for subsequent recovery times, and correlation with disease extent was calculated with Kendall taub rank correlation. Fisher-Yates test was used to correlate changes with pressure measurements and clinical course. RESULTS: Intraobserver and interobserver concordance was sensitive for detection of collateral vessels. Intraobserver agreement was 85.7% (95% CI: 42.1%, 99.6%). Interobserver agreement was high for small collateral vessels (kappa=0.74, P <.001) and fair for large collateral vessels (kappa=0.36, P=.002). MR spectroscopy was reproducible (95% CI: +/-26 seconds for proximal, +/-21 seconds for distal) and showed a correlation with disease extent (proximal calf, taub=0.84, P <.001; distal calf, taub=0.68, P=.04). Small collateral vessels increased over time (P=.04) but did not correlate with pressure measurements and clinical course. Recovery time correlated with clinical course (proximal calf, P=.03; distal calf, P=.005). CONCLUSION: MR angiography and MR spectroscopy of deoxymyoglobin can help document changes in visualization of collateral vessels and tissue perfusion in patients with CLI.

G-CSF induced arteriogenesis in humans: molecular insights into a randomized controlled trial

AIMS Recent data have demonstrated the feasibility of therapeutic induction of coronary collateral growth (arteriogenesis); however, mechanisms of action of such therapeutic collateral stimulation in humans are unknown. The aim of this study was to evaluate potential mechanisms, especially the involvement of arteriogenesis-relevant genes. METHODS AND RESULTS A total of 52 patients were randomized into two groups: subcutaneous G-CSF (10 μg/kg; n=26) or placebo (n=26). Before and after this 2-week treatment, collateral-flow index (CFI) was determined by simultaneous measurement of mean aortic, distal coronary occlusive and central venous pressure. CD34+ endothelial progenitor cells (EPC) and monocytes were quantified before, during and after treatment; gene-expression analysis of monocytes was performed with real-time polymerase chain reaction (RT-PCR). G-CSF lead to a significant increase of EPC and monocytes (4.8 and 2.6 fold, p < 0.05); for both cell types, the extent of increase correlated with CFI increase (r=0.23 and 0.14, p < 0.05). G-CSF also induced a change in gene expression of pro-and anti-arteriogenic genes in monocytes. Among nine assessed genes, three were found to be differentially regulated (IL8, JAK2, and PNPLa4; p < 0.05). CONCLUSIONS The mechanism of induction of collateral growth by G-CSF is related to an increase of EPC and of peripheral monocytes. It also leads to a change toward a pro-arteriogenic gene expression in peripheral monocytes.

A novel technique, dynamic intraligamentary stabilization creates optimal conditions for primary ACL healing: A preliminary biomechanical study

BACKGROUND Anterior cruciate ligament (ACL) rupture is a common lesion. Current treatment emphasizes arthroscopic ACL reconstruction via a graft, although this approach is associated with potential drawbacks. A new method of dynamic intraligamentary stabilization (DIS) was subjected to biomechanical analysis to determine whether it provides the necessary knee stability for optimal ACL healing. METHODS Six human knees from cadavers were harvested. The patellar tendon, joint capsule and all muscular attachments to the tibia and femur were removed, leaving the collateral and the cruciate ligaments intact. The knees were stabilized and the ACL kinematics analyzed. Anterior-posterior (AP) stability measurements evaluated the knees in the following conditions: (i) intact ACL, (ii) ACL rupture, (iii) ACL rupture with primary stabilization, (iv) primary stabilization after 50 motion cycles, (v) ACL rupture with DIS, and (vi) DIS after 50 motion cycles. RESULTS After primary suture stabilization, average AP laxity was 3.2mm, which increased to an average of 11.26mm after 50 movement cycles. With primary ACL stabilization using DIS, however, average laxity values were consistently lower than those of the intact ligament, increasing from an initial AP laxity of 3.00mm to just 3.2mm after 50 movement cycles. CONCLUSIONS Dynamic intraligamentary stabilization established and maintained close contact between the two ends of the ruptured ACL, thus ensuring optimal conditions for potential healing after primary reconstruction. The present ex vivo findings show that the DIS technique is able to restore AP stability of the knee.

Monitoring cerebral oxygenation during balloon occlusion with multichannel NIRS

We report on oxygenation changes noninvasively recorded by multichannel continuous-wave near infrared spectroscopy (CW-NIRS) during endovascular neuroradiologic interventions requiring temporary balloon occlusion of arteries supplying the cerebral circulation. Digital subtraction angiography (DSA) provides reference data on the site, timing, and effectiveness of the flow stagnation as well as on the amount and direction of collateral circulation. This setting allows us to relate CW-NIRS findings to brain specific perfusion changes. We focused our analysis on the transition from normal perfusion to vessel occlusion, i.e., before hypoxia becomes clinically apparent. The localization of the maximal response correlated either with the core (occlusion of the middle cerebral artery) or with the watershed areas (occlusion of the internal carotid artery) of the respective vascular territories. In one patient with clinically and angiographically confirmed insufficient collateral flow during carotid artery occlusion, the total hemoglobin concentration became significantly asymmetric, with decreased values in the ipsilateral watershed area and contralaterally increased values. Multichannel CW-NIRS monitoring might serve as an objective and early predictive marker of critical perfusion changes during interventions-to prevent hypoxic damage of the brain. It also might provide valuable human reference data on oxygenation changes as they typically occur during acute stroke.

Blocking brain-derived neurotrophic factor inhibits injury-induced hyperexcitability of hippocampal CA3 neurons

Brain trauma can disrupt synaptic connections, and this in turn can prompt axons to sprout and form new connections. If these new axonal connections are aberrant, hyperexcitability can result. It has been shown that ablating tropomyosin-related kinase B (TrkB), a receptor for brain-derived neurotrophic factor (BDNF), can reduce axonal sprouting after hippocampal injury. However, it is unknown whether inhibiting BDNF-mediated axonal sprouting will reduce hyperexcitability. Given this, our purpose here was to determine whether pharmacologically blocking BDNF inhibits hyperexcitability after injury-induced axonal sprouting in the hippocampus. To induce injury, we made Schaffer collateral lesions in organotypic hippocampal slice cultures. As reported by others, we observed a 50% reduction in axonal sprouting in cultures treated with a BDNF blocker (TrkB-Fc) 14 days after injury. Furthermore, lesioned cultures treated with TrkB-Fc were less hyperexcitable than lesioned untreated cultures. Using electrophysiology, we observed a two-fold decrease in the number of CA3 neurons that showed bursting responses after lesion with TrkB-Fc treatment, whereas we found no change in intrinsic neuronal firing properties. Finally, evoked field excitatory postsynaptic potential recordings indicated an increase in network activity within area CA3 after lesion, which was prevented with chronic TrkB-Fc treatment. Taken together, our results demonstrate that blocking BDNF attenuates injury-induced hyperexcitability of hippocampal CA3 neurons. Axonal sprouting has been found in patients with post-traumatic epilepsy. Therefore, our data suggest that blocking the BDNF-TrkB signaling cascade shortly after injury may be a potential therapeutic target for the treatment of post-traumatic epilepsy.