Management of 'no-reflow' complicating reperfusion therapy

Chronic Total Occlusion Percutaneous Coronary Intervention in Patients With Prior Coronary Artery Bypass Graft: Current Evidence and Future Perspectives

Coronary chronic total occlusion (CTO), which occurs in 18. 4-52% of all patients referred for coronary angiography, represents one of the last barriers in coronary intervention. Approximately half of all patients with prior coronary artery bypass graft (CABG), who undergo coronary angiography, are diagnosed with coronary CTO. In fact, these patients often develop recurrent symptoms and events, necessitating revascularization. Currently, there is neither a consensus nor developed guidelines for the treatment of CTO patients with prior CABG, and the prognosis of these patients remains unknown. In this review, we discuss current evidence and future perspectives on CTO revascularization in patients with prior CABG, with special emphasis on clinical and lesion characteristics, procedural success rates, periprocedural complications, and long-term outcomes.

Impact of target vessel choice on outcomes following percutaneous coronary intervention in patients with a prior coronary artery bypass graft

OBJECTIVES

To evaluate and compare characteristics and clinical outcomes of percutaneous coronary intervention (PCI) among target vessel types in patients with a prior coronary artery bypass graft (CABG) surgery.

BACKGROUND

Patients with a prior CABG often require repeat revascularization with PCI. Graft PCI has been associated with worse outcomes compared to native vessel PCI, yet the optimal PCI strategy in prior CABG patients remains unknown.

METHODS

We stratified prior CABG patients who underwent PCI at a tertiary-care center between 2009 and 2017 by target vessel type: native vessel, venous graft, and arterial graft. The primary outcome of major adverse cardiac events (MACE) was a composite of all-cause death, myocardial infarction, stent thrombosis, or target vessel revascularization up to 1 year post-PCI.

RESULTS

Prior CABG patients (n = 3983) represented 19.5% of all PCI interventions during the study period. PCI was most frequently performed on native vessels (n = 2928, 73.5%) followed by venous (n = 883, 22.2%) and arterial grafts (n = 172, 4.3%). Procedural success and complications were similar among the groups; however, slow- and no-reflow phenomenon was more common in venous graft PCI compared to native vessel PCI (OR 4.78; 95% CI 2.56-8.95; p < 0.001). At 1 year, there were no significant differences in MACE or in its individual components.

CONCLUSIONS

Target vessel choice did not appear to affect MACE at 1 year in a large cohort of patients with prior CABG undergoing PCI. Whether PCI of surgical grafts versus native arteries truly results in similar outcomes warrants further investigation in randomized controlled trials.

Effects of intravenous diltiazem in a rat model of experimental coronary thrombotic microembolism

The aim of this study was to assess the feasibility of evaluating the therapeutic effects of intravenous diltiazem in a newly established rat model of coronary thrombotic micro-embolism (CME). CME was induced by injecting 0.199 ml saline containing 5 mg of automicrothrombotic particulates (∼10 μm) into the aorta of Sprague Dawley rats. The injection was carried out over 10 sec using a tuberculin syringe with a 28-gauge needle. The CME model rats were randomly divided into untreated (CME, n=38) and diltiazem-treated (CME+DIL, n=38) groups. Diltiazem (1 mg/ml, 50 μg/min/kg) was intravenously injected using an infusion pump through the tail vein for 175 min, 5 min following the injection of the automicrothrombotic particulates. Hemodynamic measurements, echocardiography and pathohistological examinations were performed at various time-points (3 h, 24 h and 7 and 28 days) postoperatively. Arteriolar thrombosis, multifocal myocardial necrosis, inflammatory cell infiltration with markedly increased myocardial tumor necrosis factor α (TNF-α) and interleukin-6 (IL-6) expression, reduced left ventricular (LV) systolic function and increased plasma von Willebrand factor (vWF), endothelin-1 (ET-1) and serum c-troponin I (c-TnI) levels (indicating vascular endothelial injury and myocardial necrosis) were observed in the CME model rats. These pathological responses in CME rats were partly attenuated by intravenous diltiazem treatment. The present CME model is suitable for evaluating the therapeutic effects of intravenous diltiazem; intravenous diltiazem treatment significantly improved cardiac function through alleviating inflammatory responses and microvascular thrombotic injury in this rat model of CME.

Current percutaneous treatment strategies for saphenous vein graft disease

Coronary artery bypass graft surgery remains one of the most widely performed surgical procedures in North America and aortocoronary saphenous vein grafts (SVG) are the most frequently used surgical conduits. SVG disease (SVGD) remains the leading cause of symptomatic coronary artery disease postcoronary artery bypass graft. When optimal medical therapy is ineffective, repeat surgery is associated with higher mortality combined with less favorable clinical and angiographic results, thus percutaneous revascularization on SVG is currently the standard of care for the revascularization of SVGD. Balloon angioplasty, bare metal stents, polytetrafluoroethylene-covered stents, and drug-eluting stents have been extensively investigated for SVG interventions. Multiple recent randomized trials and meta-analyses have confirmed the pathophysiologic and clinical differences between SVGD and coronary artery disease. Decisions such as patient selection, premedication, stent, and protection device characteristics should be carefully considered to achieve optimal procedural and clinical results. Acute coronary syndromes due to SVG involvement, chronic total occlusions, retrograde approaches, and SVG perforation management are newer fields requesting additional research.

Alveolar macrophages and Toll-like receptor 4 mediate ventilated lung ischemia reperfusion injury in mice

BACKGROUND

Ischemia-reperfusion (I-R) injury is a sterile inflammatory process that is commonly associated with diverse clinical situations such as hemorrhage followed by resuscitation, transient embolic events, and organ transplantation. I-R injury can induce lung dysfunction whether the I-R occurs in the lung or in a remote organ. Recently, evidence has emerged that receptors and pathways of the innate immune system are involved in recognizing sterile inflammation and overlap considerably with those involved in the recognition of and response to pathogens.

METHODS

The authors used a mouse surgical model of transient unilateral left pulmonary artery occlusion without bronchial involvement to create ventilated lung I-R injury. In addition, they mimicked nutritional I-R injury in vitro by transiently depriving cells of all nutrients.

RESULTS

Compared with sham-operated mice, mice subjected to ventilated lung I-R injury had up-regulated lung expression of inflammatory mediator messenger RNA for interleukin-1β, interleukin-6, and chemokine (C-X-C motif) ligand-1 and -2, paralleled by histologic evidence of lung neutrophil recruitment and increased plasma concentrations of interleukin-1β, interleukin-6, and high-mobility group protein B1 proteins. This inflammatory response to I-R required toll-like receptor-4 (TLR4). In addition, the authors demonstrated in vitro cooperativity and cross-talk between human macrophages and endothelial cells, resulting in augmented inflammatory responses to I-R. Remarkably, the authors found that selective depletion of alveolar macrophages rendered mice resistant to ventilated lung I-R injury.

CONCLUSIONS

The data reveal that alveolar macrophages and the pattern recognition receptor toll-like receptor-4 are involved in the generation of the early inflammatory response to lung I-R injury.

Chinese herbal medicine Naoxintong capsule combined with dual antiplatelet therapy in a rat model of coronary microembolization induced by homologous microthrombi

OBJECTIVE

In the present study, the efficacy of Naoxintong capsule (NXT), a compound Chinese herbal medicine, combined with dual antiplatelet therapy (DA) in a rat model of coronary microembolization (CME) was evaluated.

METHODS

CME in rats was developed by injecting a suspension of microthrombotic particles into the left ventricle when the ascending aorta was obstructed. Microthrombotic particles were generated from the clots of rats sized by filtration through a screen (aperture diameter, 38 μm). A total of 95 rats were randomly divided into six groups, including control group, sham-operation (sham) group, CME model (CME) group, and NXT, DA, and NDA (NXT plus DA) groups. Rats in treatment groups were administered intragastrically with NXT, DA, and NDA, respectively, from 3 d before to 7 d after operation. All rats were sacrificed on day 7 post-operationally, and samples of blood and heart were collected. The complete data of 69 rats were obtained. The incidence of CME (CME%) was evaluated by hematoxylin-eosin staining. Bleeding time (BT) and clotting time (CT) were measured by means of tail cutting and glass slide methods, respectively. Adenosine diphosphate-induced maximum platelet aggregation rate (PAR) was assessed with turbidimetry. Platelet counts were examined by an automated hematology analyzer. The levels of serum P-selectin, interleukin (IL)-6, IL-10, endothelin (ET-1) and endothelial nitric oxide synthase (eNOS) were all detected by enzyme-linked immunosorbent assay.

RESULTS

Compared with control and sham groups, CME group had an increase in CME%, PAR, P-selectin, IL-6 and ET-1 (P<0.01, P<0.01), and a decrease in BT, CT, IL-10 and eNOS (P<0.01, P<0.01); compared with CME group, the groups receiving medications had an increase in BT, CT, IL-10 and eNOS (P<0.05 or P<0.01), and a decrease in CME%, PAR, P-selectin, IL-6 and ET-1 (P<0.05 or P<0.01), with DA group increasing most in BT and CT and decreasing most in PAR and P-selectin, and with NDA group increasing most in IL-10 and eNOS and decreasing most in CME%, IL-6 and ET-1. In terms of platelet counts, there was no statistically significant difference among groups (P>0.05).

CONCLUSION

NXT combined with DA can decrease CME%. The probable mechanism is that this therapy can appropriately inhibit platelet aggregation, balance the pro- and anti-inflammatory cytokines as well as serum ET-1 and eNOS. This therapy can also reduce risk of intraoperative bleeding during DA therapy.

Intimal hyperplasia in balloon dilated coronary arteries is reduced by local delivery of the NO donor, SIN-1 via a cGMP-dependent pathway

Background

To elucidate the mechanism by which local delivery of 3-morpholino-sydnonimine (SIN-1) affects intimal hyperplasia after percutaneous transluminal coronary angioplasty (PTCA).

Methods

Porcine coronary arteries were treated with PTCA and immediately afterwards locally treated for 5 minutes, with a selective cytosolic guanylate cyclase inhibitor, 1 H-(1,2,4)oxadiazole(4,3-alpha)quinoxaline-1-one (ODQ) + SIN-1 or only SIN-1 using a drug delivery-balloon. Arteries were angiographically depicted, morphologically evaluated and analyzed after one and eight weeks for actin, myosin and intermediate filaments (IF) and nitric oxide synthase (NOS) contents.

Results

Luminal diameter after PCI in arteries treated with SIN-1 alone and corrected for age-growth was significantly larger as compared to ODQ + SIN-1 or to controls (p < 0.01). IF/actin ratio after one week in SIN-1 treated segments was not different compared to untreated segments, but was significantly reduced compared to ODQ + SIN-1 treated vessels (p < 0.05). Expression of endothelial NADPH diaphorase activity was significantly lower in untreated segments and in SIN-1 treated segments compared to controls and SIN-1 + ODQ treated arteries (p < 0.01). Restenosis index (p < 0.01) and intimal hyperplasia (p < 0.01) were significantly reduced while the residual lumen was increased (p < 0.01) in SIN-1 segments compared to controls and ODQ + SIN-1 treated vessels.

Conclusions

After PTCA local delivery of high concentrations of the NO donor SIN-1 for 5 minutes inhibited injury induced neointimal hyperplasia. This favorable effect was abolished by inhibition of guanylyl cyclase indicating mediation of a cyclic guanosine 3',5'-monophosphate (cGMP)-dependent pathway. The momentary events at the time of injury play crucial role in the ensuring development of intimal hyperplasia.

Early versus late ST-segment resolution and clinical outcomes after percutaneous coronary intervention for acute myocardial infarction

Background. Absence of complete ST-segment resolution (STR) after percutaneous coronary intervention (PCI) for ST-segment-elevation myocardial infarction (STEMI) is a determinant of mortality. Traditionally, STR is determined on the coronary care unit (CCU) 60 to 90 minutes after the initiation of reperfusion therapy. We studied the prognostic value of STR immediately after PCI. Methods. We analysed 223 consecutive patients with STEMI and successful PCI. Continuous ECG data were collected during PCI and at 30 minutes after arrival on the CCU (mean time 81±17 minutes after reflow of the culprit artery). Patients were divided into three groups: patients with complete STR immediately after PCI ('early'), patients with complete and persistent STR at 30 minutes on the CCU, but not immediately after PCI ('late') and patients without STR. One-year follow-up was obtained for death and rehospitalisation for major adverse cardiac events. Cox proportional hazards regression was used to evaluate the association between STR and outcome. Results. Early STR occurred in 115 (52%) and late STR in 43 (19%) patients. Patients with early or late STR had a lower incidence of one-year cardiac death than those without STR (1.9 vs. 9.2%; p=0.02). In contrast, rehospitalisation occurred more frequently in patients with early or late STR (20.3 vs. 6.2%; p=0.009). As compared with patients without STR, early and late STR had a similar prognostic value (hazard ratios [95% confidence interval] for cardiac death 0.40 [0.08-2.03] and 0.25 [0.03-2.08]).Conclusions. We found no (major) change in prognostic value of STR during the 0 to 90 minutes time window after PCI. (Neth Heart J 2010;18:416-22.).

Poloxamer 188 prolongs survival of hypotensive resuscitation and decreases vital tissue injury after full resuscitation

Hypotensive resuscitation prolongs survival of patients with severe bleeding until they can undergo hemorrhage control. However, its value is limited by continuing ischemic injury. Purified poloxamer 188 (P188), a copolymer with rheological and cytoprotective activities, was known to reduce mortality of hemorrhagic shock when used as an adjunct to full resuscitation with fresh whole blood and crystalloid. Studies were undertaken to determine if it could prolong survival and reduce reperfusion injury during prolonged hypotensive resuscitation when added to the best regimen currently available. Unanesthetized rats were bled to a MAP of 30 mmHg for 30 min under computer control. They then received hypotensive resuscitation with Hextend or Hextend + P188 to maintain a MAP of 60 mmHg until death. Poloxamer 188 improved autoresuscitation, reduced fluid requirements, and increased the survivable duration of hypotensive resuscitation by more than 3 h (P < 0.01). Additional studies assessed tissue damage after shock and hypotensive resuscitation with Hextend followed by full resuscitation with crystalloid. In these studies, P188 blunted the no-reflow phenomenon and largely prevented myocardial injury, pulmonary inflammation, small bowel damage, renal tubular necrosis, hepatic central lobular necrosis, and apoptosis of splenic germinal centers that occurred during full resuscitation. Additional studies demonstrated that P188 increased survival from 0% to 75% in 50% volume-controlled hemorrhage (P < 0.001). Finally, P188 did not increase bleeding in uncontrolled hemorrhage produced by 75% tail amputation. Because P188 prolongs survival, decreases fluid requirements, and reduces tissue damage, it deserves further consideration as an adjunct to hypotensive resuscitation.

Current status of distal embolization in percutaneous coronary intervention: mechanical and pharmacological strategies

Distal embolization during percutaneous coronary intervention for acute myocardial infarction or saphenous vein graft disease may result in microvascular obstruction and the 'no-reflow' phenomenon. The incidence of distal embolization ranges from 2 to 42% in saphenous vein graft intervention and from 6 to 15% in primary percutaneous coronary intervention and is associated with impaired myocardial perfusion and poor outcome. Several mechanical and pharmacological strategies have been proposed to prevent or to treat embolization in percutaneous coronary intervention and have been tested in clinical trials. The pivotal role of distal embolization in the pathophysiology of microvascular obstruction will lead to the further development of preventive and therapeutic strategies. Strategies to counteract distal embolization and future directions are discussed in this review.

Effect of Chinese drugs for supplementing Qi, nourishing Yin and activating blood circulation on myocardial perfusion in patients with acute myocardial infarction after revascularization

OBJECTIVE

To observe the effects of Chinese drugs for supplementing qi, nourishing yin and activating blood circulation on the myocardial perfusion in acute myocardial infarction (AMI) patients after revascularization.

METHODS

Eighty patients with anterior or inferior ventricular wall AMI, who had received revascularization by intravenous thrombolysis or coronary bypass, were randomized into the treated group and the control group equally, both treated with conventional Western medical treatment, but combined, respectively, with Xinyue Capsule (, XYC) plus Composite Salvia Tablet (CST) and placebo for 3 months. Dobutamine stress echocardiography (DSE) was performed 14 days and 3 months after revascularization, respectively on every patient to observe blood perfusion extent (b value), myocardial perfusion velocity (k value) and local blood fl ow volume (k x b) in left ventricular infarction-related vascular segments under stressed state.

RESULTS

With 5 cases dropping out in the observation period (3 in the treated group and 2 in the control group), the trial was completed in 75 patients in total. The 14-day DSE shows that the b value and k x b value of left anterior ventricular wall mid segment and apex segment, and the k value of apex segment in patients with anterior wall AMI, as well as the b value and k x b of basal segment in patients with inferior wall AMI in the treated group were significantly higher than those in the control group (P<0.05 or P<0.01). The 3-month DSE shows that the b value of apex segment, k x b value of basal segment, mid segment and apex segment of left anterior ventricular wall in patients with anterior wall AMI as well as the b value and k x b value of basal segment of left inferior ventricular wall in patients with inferior wall AMI were all higher in the treated group than those in the control group, respectively (P<0.05). The comparison between 14-day DSE and 3-month DSE in the treated group showed that the b value of apex segment of left anterior ventricular wall in patients with anterior wall AMI and the k x b value of apex segment and mid segment of left inferior ventricular wall in patients with inferior wall AMI significantly increased along with the on-going treatment (P<0.05).

CONCLUSION

Therapy with Chinese drugs for supplementing qi, nourishing yin and activating blood circulation in combination with conventional Western medical treatment could obviously improve the blood perfusion at the myocardial tissue level in infarction-related vascular segments.