tert-Butyl Esters as Potential Reversible Chain Transfer Agents for Concurrent Cationic Vinyl-Addition and Ring-Opening Copolymerization of Vinyl Ethers and Oxiranes.

tert-Butyl esters are demonstrated to function as chain transfer agents (CTAs) in the cationic copolymerization of vinyl ether (VE) and oxirane via concurrent vinyl-addition and ring-opening mechanisms. In the copolymerization of isopropyl VE and isobutylene oxide (IBO), the IBO-derived propagating species reacts with tert-butyl acetate to generate a copolymer chain with an acetoxy group at the ω-end. This reaction liberates a tert-butyl cation; hence, a polymer chain with a tert-butyl group at the α-end is subsequently generated. Other tert-butyl esters also function as CTAs, and the substituent attached to the carbonyl group affects the chain transfer efficiency. In addition, ethyl acetate does not function as a CTA, which suggests the importance of the liberation of a tert-butyl cation for the chain transfer process. Chain transfer reactions by tert-butyl esters potentially occur reversibly through the reaction of the propagating cation with the ester group at the ω-end of another chain.

Obstructive sleep apnea is associated with increased coronary plaque instability: an optical frequency domain imaging study.

Obstructive sleep apnea (OSA) is associated with coronary artery disease (CAD) and with an increased risk for myocardial infarction, stroke or death due to cardiovascular disease. Optical frequency-domain imaging (OFDI) is a useful modality for evaluating the characteristics of atherosclerotic plaque. The purpose of the study was to use OFDI to investigate the association of OSA with coronary plaque characteristics in patients undergoing percutaneous coronary intervention (PCI). We retrospectively analyzed OFDI data for coronary artery plaques from 15 patients with OSA and 35 non-OSA patients treated between October 2015 and October 2018. Plaque morphology was evaluated for 70 lesions, including 21 from patients with OSA and 49 from non-OSA patients. Compared with the non-OSA group, patients with OSA had significantly higher prevalences of thinned cap fibroatheroma (TCFA) (67% vs. 35%, P = 0.014) and microchannels (86% vs. 55%, P = 0.014); a significantly higher mean lipid index (1392 ± 982 vs. 817 ± 699, P = 0.021), macrophage grade (8.4 ± 6.4 vs. 4.8 ± 4.5, P = 0.030), and maximum number of microchannels (1.5 ± 1.0 vs. 0.7 ± 0.7, P = 0.001); and a significantly lower mean minimum fibrous cap thickness (69.4 ± 28.7 vs. 96.1 ± 51.8 µm, P = 0.008). This OFDI analysis suggests that OSA is associated with unstable plaque characteristics in patients with CAD. More intensive medical management for stabilization of coronary atherosclerotic plaque is required in patients with OSA.

Stabilization of symptomatic carotid atherosclerotic plaques by statins: a clinico-pathological analysis.

Human and animal studies have revealed a stabilization of atherosclerotic plaques by statins. However, the stabilization of human carotid plaques has not been thoroughly described pathologically. This analysis explored the relationship between statin therapy and plaque stability in carotid endarterectomy (CEA) specimens. We analyzed specimens harvested between May 2015 and February 2017, from 79 consecutive patients presenting with > 70% carotid artery stenoses, of whom 66 were untreated (group 1) and 13 treated (group 2) with a statin. Immunohistochemistry was performed, using an endothelial specific antibody to CD31, CD34 and platelet derived growth factor receptor-ß. The prevalence of plaque ruptures (P = 0.009), lumen thrombi (P = 0.009), inflammatory cells (P = 0.008), intraplaque hemorrhages (P = 0.030) and intraplaque microvessels (P < 0.001) was significantly lower in group 2 than in group 1. Among 66 patients presenting with strokes and infarct sizes > 1.0 cm3 on magnetic resonance imaging, the mean infarct volume was significantly smaller (P = 0.031) in group 2 (4.2 ± 2.5 cm3) than in group 1 (8.2 ± 7.1 cm3). The difference in mean concentration of low-density lipoprotein cholesterol between group 1 (121 ± 32 mg/dl) and group 2 (105 ± 37 mg/dl) was non-significant (P = 0.118). This analysis of plaques harvested from patients undergoing CEA suggests that statin therapy mitigates the plaque instability, which, in patients presenting with strokes, might decrease infarct volume.

Pathological Quantification of Carotid Artery Plaque Instability in Patients Undergoing Carotid Endarterectomy.

BACKGROUND: Unstable atherosclerotic carotid plaques cause cerebral thromboemboli and ischemic events. However, this instability has not been pathologically quantified, so we sought to quantify it in patients undergoing carotid endarterectomy (CEA).Methods and Results:Carotid plaques were collected during CEA from 67 symptomatic and 15 asymptomatic patients between May 2015 and August 2016. The specimens were stained with hematoxylin-eosin and elastica-Masson. Immunohistochemistry was performed using an endothelial-specific antibody to CD31, CD34 and PDGFRß. The histopathological characteristics of the plaques were studied. By multiple-variable logistic regression analysis, plaque instability correlated with the presence of plaque rupture [odds ratio (OR), 9.75; P=0.013], minimum fibrous cap thickness (OR per 10 µm 0.70; P=0.025), presence of microcalcifications in the fibrous cap (OR 7.82; P=0.022) and intraplaque microvessels (OR 1.91; P=0.043). Receiver-operating characteristics analyses showed that these factors combined into a single score diagnosed symptomatic carotid plaques in patients with carotid artery stenosis with a high level of accuracy (area under the curve 0.92; 95% confidence interval 0.85-0.99 vs. asymptomatic). CONCLUSIONS: This analysis of carotid plaque instability strongly suggested that the diagnostic scoring of carotid plaque instability improves the understanding and treatment of carotid artery disease in patients undergoing CEA.

Intraprocedural left ventricular free wall rupture diagnosed by left ventriculogram in a patient with infero-posterior myocardial infarction and severe aortic stenosis.

BACKGROUND: Left ventricular wall rupture remains a major lethal complication of acute myocardial infarction and hypertension is a well-known predisposing factor of cardiac rupture after myocardial infarction. CASE PRESENTATION: An 87-year-old man was admitted to our hospital, diagnosed as acute myocardial infarction (AMI). The echocardiogram showed 0.67-cm(2) aortic valve, consistent with severe aortic stenosis (AS). A coronary angiography showed a chronic occlusion of the proximal left circumflex artery and a 99 % stenosis and thrombus in the mid right coronary artery. During percutaneous angioplasty of the latter, transient hypotension and bradycardia developed at the time of balloon inflation, and low doses of noradrenaline and etilefrine were intravenously administered as needed. The patient suddenly lost consciousness and developed electro-mechanical dissociation. Cardio-pulmonary resuscitation followed by insertion of an intra-aortic balloon pump (IABP) and percutaneous cardiopulmonary support were initiated. The echocardiogram revealed moderate pericardial effusion, though the site of free wall rupture was not distinctly visible. A left ventriculogram clearly showed an infero-posterior apical wall rupture. Surgical treatment was withheld because of the interim development of brain death. CONCLUSIONS: In this patient, who presented with severe AS, the administration of catecholamine to stabilize the blood pressure probably increased the intraventricular pressures considerably despite apparently normal measurements of the central aortic pressure. IABP, temporary pacemaker, or both are recommended instead of intravenous catecholamines for patients with AMI complicated with significant AS to stabilize hemodynamic function during angioplasty.

Severe mitral regurgitation due to mitral leaflet aneurysm diagnosed by three-dimensional transesophageal echocardiography: a case report.

BACKGROUND: A small mitral valve aneurysm (MVA) presenting as severe mitral regurgitation (MR) is uncommon. CASE PRESENTATION: A 47-year-old man with a history of hypertension complained of exertional chest discomfort. A transthoracic echocardiogram (TTE) revealed the presence of MR and prolapse of the posterior leaflet. A 6-mm in diameter MVA, not clearly visualized by TTE, was detected on the posterior leaflet on a three-dimensional (3D) transesophageal echocardiography (TEE). The patient underwent uncomplicated triangular resection of P2 and mitral valve annuloplasty, and was discharged from postoperative rehabilitation, 2 weeks after the operation. Histopathology of the excised leaflet showed myxomatous changes without infective vegetation or signs of rheumatic heart disease. CONCLUSIONS: A small, isolated MVA is a cause of severe MR, which might be overlooked and, therefore, managed belatedly. 3D TEE was helpful in imaging its morphologic details.

Stent thrombosis caused by metal allergy complicated by protein S deficiency and heparin-induced thrombocytopenia: a case report and review of the literature.

A 43-year-old woman recipient of a bare metal coronary stent during an acute anterior myocardial infarction was repeatedly hospitalized with recurrent stent thrombosis (ST) over the following 3 years. Emergent coronary angiography showed a thrombus in the in-stent segment of the proximal left anterior descending artery. We repeatedly aspirated the thrombus, which immediately reformed multiple times. The discontinuation of heparin and administration of thrombolytics and argatroban, followed by repeated balloon dilatations, ended the formation of new thrombi. The patient was found to be allergic to nickel, protein S deficient and carrier of heparin-induced thrombocytopenia antibody. We discuss this case in the context of a) literature pertaining to acute coronary syndromes in the young, and b) the detailed investigations needed to identify thrombotic risk factors. Steroids may be effective to prevent recurrent ST caused by stent allergy.

Lethal complication: Ventricular septal perforation and right ventricular infarction after acute myocardial infarction.

Here, we report a case of ventricular septal perforation complicated with right ventricular infarction after inferior acute myocardial infarction, which was associated with a poor clinical outcome despite the successful surgical treatment.

Impact of COVID-19 pandemic on emergency medical system and management strategies in patients with acute coronary syndrome.

The global coronavirus disease-2019 (COVID-19) pandemic is associated with reduced rate of percutaneous coronary intervention (PCI). However, there were a few data showing how emergency medical system (EMS) and management strategies for acute coronary syndrome (ACS) changed during the pandemic. We sought to clarify changes on characteristics, treatments, and in-hospital mortality of patients with ACS transported via EMS between pre- and post-pandemic. We examined consecutive 656 patients with ACS admitted to Sapporo City ACS Network Hospitals between June 2018 and November 2021. The patients were divided into pre- and post-pandemic groups. The number of ACS hospitalizations declined significantly during the pandemic (proportional reduction 66%, coefficient -0.34, 95% CI -0.50 to -0.18, p < 0.001). The median time from an EMS call to hospital was significantly longer in post-pandemic group than in pre-pandemic group (32 [26-39] vs. 29 [25-36] min, p = 0.008). There were no significant differences in the proportion of patients with ACS receiving PCI, and in-hospital mortality between the groups. The COVID-19 pandemic had a significant impact on EMS and management in patients with ACS. Although a significant decline was observed in ACS hospitalizations, the proportion of patients with ACS receiving emergency PCI remained during the pandemic.

Paradoxical doppler echocardiographic parameters during recovery of left atrial contractility after spontaneous conversion from paroxysmal atrial fibrillation to sinus rhythm.

Paroxysmal atrial fibrillation (PAF) reduces atrial contractility due to atrial remodeling, but little is known about the process by which contractile function is reconstituted after spontaneous conversion to sinus rhythm (SR). A 63-year-old healthy man developed PAF. PAF persisted for 2 days before spontaneous conversion to SR. Serial echocardiograms were performed at 1, 24 h, 3/4/7 days after conversion. Longitudinal myocardial strain during the pump phase of the left atrium (LA) was generally reduced at 1 h. Normal strain of the LA was restored at 3 days with the exception of the lateral wall, where restoration was delayed until 4 days. The ratio between the mitral early and atrial diastolic velocities (E/A) at 24 h was within a pseudonormal range at 1.8, but the ratio between E and early mitral annulus velocity (e': E/e') remained normal. The E/A ratio gradually decreased until 7 days post conversion, but the E/e' ratio remained normal throughout the observation period.

Eicosapentaenoic acid therapy is associated with decreased coronary plaque instability assessed using optical frequency domain imaging.

BACKGROUND: The relationship between eicosapentaenoic acid (EPA) therapy and coronary plaque stability assessed by optical frequency domain imaging (OFDI) has not been thoroughly described. HYPOTHESIS: EPA therapy is associated with decreased plaque instability in patients undergoing percutaneous coronary intervention (PCI) using OFDI. METHODS: Data on coronary artery plaques from 121 patients who consecutively underwent PCI between October 2015 and July 2018 were retrospectively analyzed. Of these patients, 109 were untreated (no-EPA group), whereas 12 were treated with EPA (EPA group). Each plaque's morphological characteristics were analyzed using OFDI. RESULTS: We used 1:4 propensity score matching for patients who received or did not receive EPA therapy before PCI. Baseline characteristics were balanced between both groups (age, sex, body mass index, diabetes mellitus, hypertension, dyslipidemia, chronic kidney disease, smoking, previous PCI or coronary artery bypass grafting, previous myocardial infarction, prior statin use, acute coronary syndrome, hemoglobin A1c level, low-density lipoprotein cholesterol concentration, triglyceride concentration, and high-density lipoprotein cholesterol concentration). OFDI data from 60 patients were analyzed in this study. The EPA group had significantly lower mean lipid index (818 ± 806 vs 1574 ± 891) and macrophage grade (13.5 ± 5.9 vs 19.3 ± 7.4) but higher mean minimum fibrous cap thickness (109.2 ± 55.7 vs 81.6 ± 36.4 µm) than the no-EPA group (P = 0.010, 0.019, and 0.040, respectively). Multiple logistic regression analyses showed that prior EPA use was independently associated with lower lipid index and macrophage grade (P = 0.043 and 0.024, respectively). CONCLUSION: This OFDI analysis suggests that EPA therapy is associated with decreased plaque instability in patients undergoing PCI.

Relationship between left main and left anterior descending arteries bifurcation angle and coronary artery calcium score in chronic kidney disease: A 3-dimensional analysis of coronary computed tomography.

BACKGROUND: A high coronary artery calcium score (CACS) predicts a poor prognosis in patients with coronary artery disease. We examined the relationship between the bifurcation angle and the CACS of the left main (LM) and left anterior descending (LAD) arteries in patients suffering from chronic kidney disease (CKD). METHODS: We analyzed the data of 121 patients who underwent coronary computed tomography between October 2014 and June 2015 and whose estimated glomerular filtration rate (eGFR) was <60 ml/min/1.73 m2. The LM-LAD bifurcation angle was measured by 3-dimensional coronary computed tomography. The CACS of the LM-LAD arteries was also calculated. We excluded stent recipients and patient who had undergone coronary artery bypass graft surgery. RESULTS: In the overall sample, the mean ± standard deviation (range) LM-LAD bifurcation angle was 35.9 ± 11.4° (6.8-79.4°) and mean CACS was 227 ± 351 (0 to 1,695). The mean LM-LAD arteries angle was 40.3° ± 10.0° in 39 patients whose CACS was ≥200, versus 33.8° ± 11.6° in 82 patients with CACS <200 (p = 0.003). A weak, but positive correlation (r = 0.269, p = 0.003) was observed between the LM-LAD arteries angle and CACS of the LM-LAD arteries. By multiple variable analysis, hemoglobin A1c, triglycerides, eGFR and the LM-LAD arteries angle were independent predictors of a high CACS of the LM-LAD arteries. CONCLUSION: In patients with CKD, a wide LM-LAD arteries angle was associated with a high CACS of the LM-LAD arteries. The prognostic value of this observation warrants further evaluation.

Investigation on the optimal implantation site and setting of Reveal LINQ® avoiding interference with performance of transthoracic echocardiography.

BACKGROUND: The optimal implantation site of a new implantable cardiac monitor (ICM) named Reveal LINQ® may be limited based on a sufficient amplitude of R wave potential (AEP) acquisition because it is the same anatomic area used for transthoracic echocardiography (TTE). METHODS: Among 18 healthy volunteers, we assessed AEPs in 3 combinations through parasternal placement of 2 electrodes, (i) in the 4th intercostal space (ICS; site A/setting a; A/a), (ii) the same setting in the 5th ICS (site B/setting a; B/a), and (iii) in a sagittal plane relative to the left sternal border at the 4th ICS (site A/setting b; A/b), and further measured AFPs in several body positions in all site-setting combinations: supine, left and right lateral decubitus, sitting, and standing. The degree of interference with TTE performance was assessed by placement of an imitation ICM in setting a at both sites A and B. RESULTS: Only the AEPs in A/a and B/a met the criteria (AEP ≥ 0.3 mV) in all positions. The AEPs in the supine position with all combinations were higher than those achieved in other positions (P < .001). The imitation interfered with TTE performance at site A among 78% of subjects, but only 17% at site B (P = .0006). The end-diastolic dimension of the left ventricle at site A was decreased after the imitation placement (P = .028). At site B, all female subjects complained of discomfort because their brassieres overlaid the imitation. CONCLUSION: The B/a combination is optimal; however, the personal discomfort related to brassieres should be considered.

Coronary Artery Hematoma Treated with Fenestration Using a Novel NSE Alpha® Scoring Balloon.

The optimal management of coronary intramural hematoma has not been defined. We described a case in which coronary occlusion developed due to an intramural hematoma after percutaneous coronary intervention for mid left circumflex artery (LCX). Intravascular ultrasound (IVUS) demonstrated the progression of the intramural hematoma and a totally compressed true lumen. Our approach was based on fenestration with a scoring balloon (NSE Alpha, Goodman, Japan), which allowed the deployment of an additional stent to be avoided. In conclusion, this management can be effectively and safely performed.