Occlusion Of Circumflex Coronary Artery Research Articles

Role of NOD1 in atrial myopathy associated with heart failure

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Funding: Spanish Ministry of Economy and Competitiveness and the European Regional Development Fund (ISCIII [PI17/01344 and PI20/01482]), Ministry of Education (FPU19/01973), SEC, Proyecto Traslacional 2019, FEDER, FSE, CIBER-CV, a network funded by ISCIII Introduction Heart failure (HF) is a complex syndrome that constitutes one of the leading causes of cardiovascular death worldwide. Although multifactorial mechanisms appear to be responsible of atrial and ventricular HF-myopathy, the innate immune system and the derived inflammatory response have gained much attention in the last years. Previous studies from our group have demonstrated that the nucleotide-binding oligomerization domain 1 (NOD1), a receptor of the innate immune system, plays a role in HF left ventricular (LV) dysfunction. However, its role in HF-atrial myopathy remains completely unknown. The main purpose of our study is to determine the role of NOD1 in human and experimental HF-atrial myopathy. Methods and Results The study was performed in two cohorts of individuals who underwent heart valve repair surgery, 51 non-failing individuals (NF) with LV ejection fraction (LVEF)>50% and NT-ProBNP levels<200pg/mL and 41 subjects with medium to severe reduced EF (HF)<50% and NT-ProBNP levels>200pg/mL. An informed consent was signed by all patients. Atrial myocardial tissue was excised from the atrial appendage and prepared for biochemical and histological studies. Echocardiography analysis showed that left and right atrial areas (LA and RA) were significantly increased in the HF group compared to NF, while LA and RA reservoir functions were significantly decreased in HF. Immunostaining demonstrated NOD1 location in atrial cardiomyocytes, being the protein levels of NOD1 and its specific adaptor RIP2 significantly increased in atrial tissue obtained from HF vs. NF. Although the prevalence of atrial fibrillation (AF) was significantly higher in the HF group compared to NF, the upregulation of NOD1 was not conditioned by the presence of AF. Similarly, pigs that underwent transverse aortic constriction (TAC) or proximal left circumflex coronary artery occlusion involving the LA branch (LAI), showed an upregulation of NOD1 pathway in atrial tissue, compared with the sham operated animals. Interestingly, an atrial upregulation of NOD1 axis was also observed in wild-type TAC mice, whereas Nod1-/- knockout mice showed a prevention in both structural and functional atrial remodelling induced by TAC, mainly by a prevention of intracellular calcium mishandling in isolated atrial cardiomyocytes. Finally, wild-type mice injected i.p. for 3 days with 3.3 mg/kg with a selective activator of NOD1, showed increased structural atrial remodelling and intracellular calcium mishandling compared to the vehicle-treated group. Conclusions Our results demonstrate that NOD1 axis is upregulated in human, swine and murine atrial failing myocardium. Genetic deletion of NOD1 prevented HF-atrial structural and functional remodelling, mainly by avoiding intracellular calcium mishandling, whereas its pharmacological activation induced atrial dilation and intracellular Ca2+ mishandling. All these data uncover NOD1 as a new player in atrial HF-remodelling.

Attempted retrieval of guidewire fragment using the twisting wire technique causes coronary perfusion: Case report.

Guidewire fracture is one of the biggest risks of percutaneous coronary intervention, twisting wire technique is very useful for retrieving the fractured wire, but the potential risks have been inadequately reported. Herein, we present a case of retrieval of guidewire fragments using the twisting wire technique that causes coronary perfusion. A 37-year-old male patient was admitted to our hospital for elective percutaneous coronary intervention of the left circumflex coronary artery. For chronic total occlusion of the distal left circumflex coronary artery, antegrade recanalization by wire escalation, and parallel wire techniques were attempted. However, we shockingly found that the BMW guidewire, anchored in the right coronary artery, spontaneously fractured from the proximal right coronary artery, and a lengthy fragment of the guidewire remained in the coronary. Many attempts were made to retrieve the remnant guidewire including the twisting wire technique, which leads to the perforation of the coronary. Finally, percutaneous retrieving procedures were stopped in favor of surgical extraction via a small coronary arteriotomy. This procedure was successful. To the best of our knowledge, the present case is the first reported spontaneous fracture of the guidewire. Leaving such a lengthy remnant guidewire in the artery, or leaving stenting over the wire, would impose a high risk of coronary thrombosis, perforation, and embolization. Yet, the perforation of the artery that occurred in this case, which could have had life-threatening consequences, resulted from our attempts to retrieve the guidewire using the twisting wire technique.

Ventricular injury in acute left circumflex occlusion: Exploration using precordial bipolar leads and regional VECTORCARDIOGRAMS

BackgroundPrecordial Bipolar Leads (PBLs) provide new electrocardiographic information derived from standard 12‑lead ECG recordings. ObjectivesTo explore the usefulness of PBLs in patients with acute circumflex coronary artery (CxCA) occlusion. MethodsTwelve patients undergoing elective percutaneous transluminal coronary angioplasty (PTCA) were studied before and after acute CxCA occlusion and their data were processed with new methods based on PBLs. ResultsThe findings were: 1. In right PBL V2-V1, a strong systolic current of injury moving in the left-to-right direction coexists with a strong right-to-left current of injury displayed in left standard unipolar precordial leads (V4, V5 and V6). 2. Ischemic changes lead to a significant increase (approximately 10 ms) in the QRS duration in different leads, although changes in the QRS loop rotation and folding were absent. 3. In the transverse, sagittal, and frontal planes, superimposing two PBLs and the corresponding Regional VCG facilitates the location of the J-point. 4. In the Regional VCGs of this group of patients, J-point and ST segment shifts produced an image that reminds the Greek letter omega (Ω). 5. The currents of injury flowing in opposite directions could result in electrical cancellation that minimizes ECG changes in the standard 12‑lead recordings. ConclusionsComputerized processing of digital, standard 12‑lead ECG recordings, provides new valuable diagnostic data in patients with acute CxCA occlusion. The loops revealed important information related to systolic currents of injury. Because these methods use routine 12‑lead ECG data, the procedure is based only in software applications. Condensed abstractTwelve patients undergoing PTCA were studied before and after acute CxCA occlusion and their data were processed with the new methods based on Precordial Bipolar Leads (PBLs) to explore their usefulness.The results showed strong systolic currents of injury in different and sometimes opposite directions in the right-to-left axis and ischemic alterations in the time and amplitude of the QRS waves. The superimposition of two-dimensional coordinates planes (x-y, x-z or z-y) helped to locate the J-point and to display the Regional VCG omega sign (Ω) of myocardial injury. In conclusion, computerized processing of digital ECG data provides new diagnostic information in patients with acute CxCA occlusion.

Remote ischemic preconditioning and hypoxia-induced biomarkers in acute myocardial infarction: study on a porcine model

Objectives. Remote ischemic preconditioning (RIPC) mitigates acute myocardial infarction (AMI). We hypothesized that RIPC reduces the size and severity of AMI and explored molecular mechanisms behind this phenomenon. Design. In two series of experiments, piglets underwent 60 min of the circumflex coronary artery occlusion, resulting in AMI. Piglets were randomly assigned into the RIPC groups (n = 7 + 7) and the control groups (n = 7 + 7). The RIPC groups underwent four 5-min hind limb ischemia-reperfusion cycles before AMI. In series I, the protective efficacy of RIPC was investigated by using biomarkers and echocardiography with a follow-up of 24 h. In series II, the heart of each piglet was harvested for TTC-staining to measure infarct size. Muscle biopsies were collected from the hind limb to explore molecular mechanisms of RIPC using qPCR and Western blot analysis. Results. The levels of CK-MBm (p = 0.032) and TnI (p = 0.007) were lower in the RIPC group. Left ventricular ejection fraction in the RIPC group was greater at the end of the follow-up. The myocardial infarct size in the RIPC group was smaller (p = 0.033). Western blot indicated HIF1α stabilization in the skeletal muscle of the RIPC group. PCR analyses showed upregulation of the HIF target mRNAs for glucose transporter (GLUT1), glucose transporter 4 (GLUT4), phosphofructokinase 1 (PFK1), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), enolase 1 (ENO1), lactate dehydrogenase (LDHA) and endothelial nitric oxidate synthase (eNOS). Conclusions. Biochemical, physiologic, and histologic evidence confirms that RIPC decreases the size of AMI. The HIF pathway is likely involved in the mechanism of the RIPC.

Uncommon electrocardiographic presentation of acute left circumflex coronary artery occlusion

Uncommon electrocardiographic presentation of acute left circumflex coronary artery occlusion

Acute Left Circumflex Coronary Artery Occlusion - Diagnostic Problems of Initial Electrocardiographic Changes.

Background: Acute coronary syndrome (ACS) with occlusion of the left circumflex coronary artery (LCX) poses diagnostic problems that may lead to a delay in reperfusion.Methods and Results: From a group of 1,269 consecutive patients with ACS, 138 patients with ACS due to LCX occlusion were analyzed for clinical, electrocardiographic, and angiographic presentations, as well as door-to-balloon (DTB) time. Electrocardiographic changes were classified into 4 patterns: ST-segment elevation in inferior/lateral leads (ST-E); ST-segment depression in V1–V4 (ST-D); no significant ST changes (No-ST); and others. The No-ST group was associated with a longer DTB time (P<0.0001) compared with the ST-E and ST-D groups. Compared with the No-ST and ST-E groups, the ST-D group presented with a more advanced Killip class (P=0.003), greater peak creatine phosphokinase (P=0.007) and peak creatine kinase-MB (P=0.006), more frequent proximal LCX occlusion (P=0.007), and worse 1-year outcomes (P=0.0034).Conclusions: One-third of ACS patients with LCX occlusion showed no ST-segment changes, resulting in significantly longer DTB time. Improving diagnostic accuracy is challenging but critical to avoid delayed reperfusion in these patients without electrocardiographic changes.

Isolated posterior ST-elevation myocardial infarction: the necessity of routine 15-lead electrocardiography: a case series

BackgroundTrue isolated posterior myocardial infarction is an uncommon finding of acute coronary syndrome, with an incidence rate of 3–7%. The prevalence rates of isolated posterior myocardial infarction in men and women are 72% and 28%, respectively. This uncommon finding may be attributed to multiple factors, such as unremarkable changes on 12-lead electrocardiography, a lack of awareness or knowledge, and an absence of diagnostic consensus, which leads to reperfusion delay and poor clinical outcomes.Case summaryHerein, we report three cases of acute myocardial infarction presenting as isolated ST-segment elevation in the posterior leads (V7–V9): Asian men aged 57, 62, and 53 years, who presented with ST-segment depression in V1–V3 that resolved gradually. Coronary angiography revealed a total/critical occlusion of the proximal circumflex coronary artery in all three cases. Routine and accurate interpretations of 15-lead electrocardiography (12-lead with additional V7–V9) resulted in a better sensitivity for isolated posterior myocardial infarction diagnoses, followed by a timely and opportune primary percutaneous coronary intervention.ConclusionsIsolated posterior myocardial infarction is a rare but potentially fatal event that is often accompanied by atypical and subtle changes on 12-lead electrocardiography (especially in the V1–V3 precordial leads) and may remain undetected by physicians. Therefore, the comprehensive and routine application of posterior leads is a crucial addition to the standard diagnosis and management of acute coronary syndrome in patients with subtle ST-segment changes who do not fulfill the criteria for ST-elevation myocardial infarction.

De Winter pattern in inferior leads: a rare case presentation

A 60-year-old female with a history of hypertension, diabetus mellitus, presented to the emergency room with acute chest pain. The physical examination didn´t show any abnormalities. The electrocardiogram showed upsloping ST depression at J point in the inferior leads (II, III, and aVF) with positive T wave consistent with De Winter syndrome and ST elevation in aVR. Troponin was positive (54301ng/l). The echocardiography revealed an inferior and lateral wall hypokinesia. The coronary angiography showed a circumflex sub occlusion (culprit artery), a significant stenosis of the left ascending artery and a mild right coronary artery stenosis requiring coronary bypass graft. The patient declined surgery. De Winter pattern is a STEMI-like entity. It is usually observed in anterior leads in left ascending artery (sub) occlusion. Dewinter pattern in inferior leads is very uncommon. It occurs in circumflex or right coronary artery (sub) occlusion.

Acute circumflex coronary artery occlusion; dilemma in diagnosis and management

Abstract Background Acute coronary syndrome (ACS) with occlusion of the circumflex coronary artery (LCX) poses diagnostic dilemma that may lead to a delay in reperfusion. Purpose We sought to assess the diagnostic significance of initial electrocardiography (ECG) changes in patients with acute LCX occlusion in relation to its clinical characteristics and the management. Methods From consecutive 1269 patients with ACS who were admitted to our institution during a 5-year period (2015–2019), 138 patients with ACS due to LCX occlusion were analyzed for clinical, ECG and angiographic presentation, and the door-to-balloon (DTB) time. ECG changes were classified into 4 different patterns: 1) ST-elevation in inferior/lateral leads (ST-E); 2) ST-depression in V1-V4 (ST-D); 3) no significant ST changes (No-ST); and 4) others. Results (1) No-ST pattern was found in 47 patients (34%), ST-E in 47 patients (34%), ST-D in 25 patients (18%) and others in 19 patients (14%). (2) Occlusion site: Proximal LCX; 16 patients with No-ST (34%), 6 patients with ST-E (13%), 13 patients with ST-D (52%). Distal LCX; 28 patients with No-ST (60%), 35 patients with ST-E (74%), 11 patients with ST-D (44%) (p=0.007). (Table) (3) Echocardiographic identification of left ventricular asynergy; 31 patients with No-ST (66%), 38 patients with ST-E (81%), 22 patients with ST-D (88%). (4) No-ST group was associated with longer DTB time; 245 min (170–562 min), compared to 93 min (83–121 min) in ST-E group and 97 min (70–129 min) in ST-D group (p&amp;lt;0.0001). DTB time ≤90 min was significantly uncommon in No-ST group (11%), compared to ST-E group (46%) and ST-D group (43%) (p=0.0004). (Figure) Conclusion One-third of the patients with LCX-ACS showed no ST changes, resulting in significantly longer DTB time. Improving diagnostic accuracy with anticipation for LCX-ACS and the use of echocardiographic examination and also the possible application of posterior leads (V7-V9) recording is challenging but critical to avoid delayed reperfusion and to improve outcomes in these patients without ECG changes. Funding Acknowledgement Type of funding sources: None.

Effect of Neprilysin Inhibition for Ischemic Mitral Regurgitation after Myocardial Injury.

Angiotensin receptor neprilysin inhibitor (ARNI) treatment reduces functional mitral regurgitation (MR) to a greater extent than angiotensin receptor blocker (ARB) treatment alone, but the mechanism is unclear. We evaluated the mechanisms of how ARNI has an effect on functional MR. After inducing functional MR by left circumflex coronary artery occlusion, male Sprague Dawley rats (n = 31) were randomly assigned to receive the ARNI LCZ696, the ARB valsartan, or corn oil only (MR control). Excised mitral leaflets and left ventricle (LV) were analyzed, and valvular endothelial cells were evaluated focusing on molecular changes. LCZ696 significantly attenuated LV dilatation after 6 weeks when compared with the control group (LV end-diastolic volume, 461.3 ± 13.8 µL versus 525.1 ± 23.6 µL; p < 0.05), while valsartan did not (471.2 ± 8.9 µL; p > 0.05 to control). Histopathological analysis of mitral leaflets showed that LCZ696 strongly reduced fibrotic thickness compared to the control group (28.2 ± 2.7 µm vs. 48.8 ± 7.5 µm; p < 0.05). Transforming growth factor-β and downstream phosphorylated extracellular-signal regulated kinase were also significantly lower in the LCZ696 group. Consequently, excessive endothelial-to-mesenchymal transition (EndoMT) was mitigated in the LCZ696 group compared to the control group and leaflet area was higher (11%) in the LCZ696 group than in the valsartan group. Finally, the MR extent was significantly lower in the LCZ696 group and functional improvement was observed. In conclusion, neprilysin inhibitor has positive effects on LV reverse remodeling and also attenuates fibrosis in MV leaflets and restores adaptive growth by directly modulating EndoMT.

English

BACKGROUND A significant number of patients with acute Inferior wall infarction will have RV dysfunction and most of them have occlusion of either right or left circumflex coronary artery. But RV assessment is not done routinely in echocardiographic examination. Patients present with inferior wall myocardial infarction (IWMI) subsequently develop right ventricular myocardial infarction (RVMI) and have poor prognosis. In this study we wanted to evaluate the incidence of RVMI and the role of echocardiography in assessing RV function and its impact in predicting infarct related artery by angiographic analysis in acute IWMI after thrombolysis. METHODS 86 patients with acute IWMI after thrombolysis were randomly selected. Echocardiographic examination of RV function was performed within 72 hours after thrombolysis. We applied RV echo parameters like FAC (Fractional Area Change %), TAPSE (Tricuspid Annular Plane Systolic Excursion), RV S’ (RV Systolic Excursion Velocity) and MPI (Myocardial Performance Index) to assess RV function. 48 patients underwent coronary angiogram which included 10 patients with normal RV function, rest with RV dysfunction. RESULTS Among 86 patients, we compared 64 patients of RV dysfunction with 22 patients having normal function. Echo indices were significantly lower in RV dysfunction group. FAC ( 27 ± 5.95 vs 45 ± 5.4 ) TAPSE (8.5 ± 2.0 19.59 ± 2.8 ), RV S’ ( 5.78 ± 1.26 vs 17.2 ± 3.5 ) and RVMPI (0.22 ± 0.03 vs 0.57± 0.03). Angiographic analysis of 28 of 38 patients with RV dysfunction showed significant proximal lesion in RCA as compared to only 2 among 10 patients with normal RV function. CONCLUSIONS Conventional echo examination will underestimate RV dysfunction hence we applied echo parameters like FAC, TAPSE, RV S’ and RVMPI and a significant proportion of thrombolysed acute IWMI patients were found to have RV dysfunction and it was also helpful in the prediction of infarct related artery which would be predominantly a critical proximal RCA occlusion. KEY WORDS RVMI (Right Ventricular Myocardial Infarction), FAC (Fractional Area Change %), TAPSE (Tricuspid Annular Plane Systolic Excursion), RV S’ (RV Systolic Excursion Velocity) ,MPI (Myocardial Performance Index), IRA ( Infarct Related Artery)

Effect of Presence of Ramus Intermedius Artery on Location of Culprit Lesions in Acute Left Circumflex Coronary Artery Occlusion.

Background and aimCoronary artery anatomy frequently affects location of atherosclerotic plaques and subsequent culprit lesions. We sought to clarify whether presence or absence of Ramus Intermedius coronary artery (RI) would affect location of culprit lesions in acute left circumflex (LCX) coronary artery occlusion.MethodsThe study included 180 patients, 100 with a diagnosis of non-ST elevation myocardial infarction (NSTEMI) and 80 with ST elevation myocardial infarction (STEMI). All culprit lesions were located in the LCX coronary artery. RI group included 45 patients and the No RI group included 135 patients.ResultsCulprit LCX lesions were similarly located at a comparable distance from LCX ostium in both groups and the presence of RI was not associated with significantly more proximally located culprit LCX lesions (34.7 ± 15.2 mm compared to 30.8 ± 17.9 mm respectively, p > 0.05). The frequency distribution of culprit lesions’ distance from LCX ostium showed no significant difference between both groups in any of the segments studied (10 mm each). There was no significant difference between both groups regarding markers of myocardial necrosis size as cardiac biomarkers (peak cardiac troponin-T 1077.4 ± 361.2 pg/dl vs 926 ± 462.2 pg/dl respectively, p = 0.13), (peak creatine kinase-MB 232.2 ± 81 ng/dl vs 194.7 ± 99.2 ng/dl respectively, p = 0.07) or left ventricular ejection fraction (EF 46.3 ± 6.3% vs 48.3 ± 8.3% respectively, p = 0.76).ConclusionPresence of RI coronary artery, as an additional flow divider, may not be associated with more proximal culprit lesions, compared to its absence, in cases of acute LCX coronary artery occlusion. Possible underlying pathophysiologic mechanisms remain to be clarified.

Mitral valve repair complicated by left circumflex coronary artery occlusion: The vital role of the anesthesiologist

The anatomical relationship between the mitral valve and the left circumflex coronary artery places this vessel at risk for occlusion during mitral valve repair or replacement. In view of the potential high morbidity and mortality of this complication, the anesthesiologist has a vital role in its prompt diagnosis. We present the case of a 47-year-old man who underwent a minimally invasive mitral valve repair, which was complicated by left circumflex coronary artery occlusion.

Reduction of Myocardial Necrosis After Glycosaminoglycan Administration: Effects of a Single Intravenous Administration of Heparin or N-Acetylheparin 2 Hours Before Regional Ischemia and Reperfusion.

BACKGROUND: We determined if a single administration of heparin or nonanticoagulant N-acetylheparin could reduce myocardial injury resulting from a 90-minute occlusion of the left circumflex coronary artery (LCX) and 6 hours of reperfusion in the anesthetized canine. METHODS AND RESULTS: Heparin (2 mg/kg), N-acetylheparin (2 mg/kg), or vehicle, 0.9% sodium chloride (control), was administered intravenously to separate groups of animals 2 hours before LCX occlusion. To ensure parity of LCX ischemia, only animals with ischemic zone regional blood flow < 0.16 mL/min/g tissue were included in the final analysis. Hemodynamics did not differ among the three study groups. Infarct size as a percentage of the left ventricular area at risk was obtained for each group. Myocardial infarct size was 43.0 +/- 3.9% in the vehicle, 28.8 +/- 5.8% in the heparin (P <.05 vs vehicle) and 24.7 +/- 4.6% (P <.05 vs vehicle) in the N-acetylheparin-treated animals. CONCLUSIONS: Pretreatment with heparin or its nonanticoagulant derivative, N-acetylheparin, provides significant protection to the regionally ischemic and reperfused canine myocardium independent of either plasma glycosaminoglycan concentration or alterations in the coagulation system.

Coronary Circulatory Indexes in Non-Infarct-Related Vascular Territories in a Porcine Acute Myocardial Infarction Model

ObjectivesThe aim of this study was to evaluate temporal changes in coronary hemodynamic and physiological indexes in the non-infarct-related artery (IRA), which might be affected by adjacent infarcted myocardium, using an experimental animal model of acute myocardial infarction. BackgroundThere has been debate on the reliability of fractional flow reserve and resting pressure-derived indexes, including instantaneous wave-free ratio, in the non-IRA in patients with acute ST-segment elevation myocardial infarction. MethodsIn Yorkshire swine, acute myocardial infarction was simulated with selective balloon occlusion at the left circumflex coronary artery as the IRA for 30 min. Non-IRA stenosis was created using bare-metal stent implantation in the left anterior descending coronary artery 4 weeks before the experiments. Serial changes in systemic hemodynamic status, coronary pressure, and Doppler-derived coronary flow velocity were measured in a nonoccluded left anterior descending coronary artery as the non-IRA from baseline, balloon occlusion of the left circumflex coronary artery, and 15 min after reperfusion of the left circumflex coronary artery. ResultsAmong the 6 experimental subjects, the median diameter stenosis of the non-IRA was 33.9% (interquartile range: 21.7% to 46.1%). During balloon occlusion of the IRA, there were transient significant changes in both resting and hyperemic aortic pressure, distal coronary pressure, averaged peak velocity, transstenotic pressure gradient, and microvascular resistance of the non-IRA (p < 0.020 for all). After reperfusion of the IRA, the resting averaged peak velocity (p = 0.002) and resting transstenotic pressure gradient (p = 0.004) were significantly increased and resting microvascular resistance (p = 0.004) was significantly decreased compared with their values in the baseline phase. However, the hyperemic averaged peak velocity (p = 0.479), hyperemic transstenotic pressure gradient (p = 0.778), and hyperemic microvascular resistance (p = 0.816) were not significantly different compared with those in the baseline phase. After reperfusion, fractional flow reserve in the non-IRA was not significantly different (0.94 ± 0.01 vs. 0.93 ± 0.01; p = 0.353), while coronary flow reserve (1.93 ± 0.07 vs. 1.36 ± 0.07; p = 0.025) and instantaneous wave-free ratio (0.97 ± 0.01 vs. 0.93 ± 0.01; p = 0.001) were significantly lower than baseline values. ConclusionsIn a porcine model of acute myocardial infarction, occlusion of the IRA induced significant changes in systemic hemodynamic status and coronary circulatory indexes of the non-IRA. However, after reperfusion of the IRA, fractional flow reserve did not change significantly, whereas coronary flow reserve and instantaneous wave-free ratio showed significant changes compared with baseline values.

The Condition of the Coronary Arteries in Patients with Ischemic Mitral Insufficiency

Secondary (or functional) mitral regurgitation is the result of myocardial dysfunction due to ischemic injury with relatively normal cusps. In patients with ischemic mitral insufficiency, only surgical coronary artery bypass grafting can affect the reverse remodeling of the left ventricle and reduce the degree of mitral regurgitation. One of the main pathogenetic factors for the development of this type of mitral insufficiency is myocardial ischemia. Studying the state of coronary blood flow in patients with ischemic mitral insufficiency is a primary task in the surgical treatment of this pathology.&#x0D; The aim. To study the condition of the coronary arteries in patients with ischemic mitral insufficiency.&#x0D; Material and methods. From January 2015 to December 2019, 194 patients with ischemic mitral insufficiency underwent surgical intervention at the Amosov National Institute of Cardiovascular Surgery of the NAMS of Ukraine.&#x0D; Results and Discussion. Coronarography revealed haemodynamically significant coronary artery stenosis in 190 (97.9%) patients. In 4 (2.1%) patients there was no hemodynamically significant coronary arteries stenosis. Analysis of the data of selective angiography showed that the majority of patients with ischemic mitral insufficiency had three-vessel disease (75.2%). Occlusion of the left circumflex coronary artery was observed in 33 (17.4%), and sub-occlusive changes were detected in 3 (1.6%) of patients. A completely different lesion pattern is observed for the branches of the right coronary artery. Thus, in 56 (29.4%) cases, occlusion of a particular branch was found on angiogram. Sub-occlusion of the right coronary artery was observed in 15 (7.9%) cases.&#x0D; Conclusions. In patients with ischemic mitral insufficiency, hemodynamically significant stenosis was most often observed in the anterior interventricular artery (81.6%). Comparison of the status of the right coronary artery and circumflex artery showed that the right coronary artery lesions occurred more frequently. The section of the right coronary artery between the outflow of the acute marginal branch and the branching to the posterior interventricular and lateral branches was the most vulnerable site of the coronary bed, where the frequency of occurrence of critical stenosis was 28.4%.

Unstable Angina Caused by Honeycomb-Like Coronary Lesion Identified with Use of Optical Coherence Tomography

A 67-year-old man had angina and dyspnea for several weeks during exercise and rest, and he came to our hospital for coronary angiography. He had mild ST-segment variability, without necrosis markers. Cardiac ultrasonograms revealed moderate mitral regurgitation, preserved ejection fraction, and a posterior-wall infarction scar despite no history of infarction.Coronary angiograms, which revealed no obvious culprit lesion, showed mild focal stenosis in the proximal right coronary artery, distal chronic occlusion of a small left circumflex coronary artery, and mild stenosis and haziness in the mid left anterior descending coronary artery (LAD) (Fig. 1). Suspecting thrombus in the mid LAD, we performed optical coherence tomography (OCT) (Fig. 2A). The OCT showed irregular honeycomb-like channels connecting the proximal and distal lumina, smooth appearance of the channels' inner surface and the separating septa, no visible fresh thrombus, and only a small plaque burden at the lesion site (Fig. 2B–E). We thought that the guidewire might have passed into a false lumen of a spontaneous dissection, so we advanced another guidewire, parallel to the first, to ensure entry into the distal true lumen.Given the patient's clinical instability, we performed angioplasty and implanted a bare-metal stent. Afterwards, OCT confirmed good distal flow without residual stenosis and showed a well-apposed stent, mild intima prolapse through the struts (Fig. 3A), and almost complete collapse of the parallel channels (Fig. 3B). Two years later, the patient was asymptomatic and well.Lesions of this type were previously associated with recanalized thrombus.1,2 They were compared with Swiss cheese,1 or, when channels were spread over a larger area, with a honeycomb—a term coined by Toutouzas and colleagues.2In our patient, the small plaque burden at the lesion site seen on coronary angiography suggested an organized coronary embolus, but OCT revealed a recanalized thrombus. This rare case highlights the need to recognize the limits of angiography and to use complementary imaging methods, especially when angiographic appearance is discordant with clinical status.

P1470Myocardial dysfunction index: a novel myocardial strain parameter for diagnosing myocardial ischemia

Abstract Background and purpose Peak systolic strain (ε-sys) derived from speckle tracking echocardiography (STE) is a useful parameter for assessing regional contractile dysfunction during acute ischemia. However, low ε-sys does not always indicate myocardial ischemia because of its relatively large variation in segmental normal ranges and intervendor differences. Therefore, comparison of strain before and after an ischemic event and demonstration of a decrease in ε-sys should be necessary to confirm myocardial ischemia, which is not always possible in clinical situations. It is well known that early systolic lengthening (ESL) and post-systolic shortening (PSS) occur during acute ischemia. We hypothesized that ESL and PSS would correlate with the decrease in ε-sys and integrated analysis of ESL and PSS could be useful to diagnose the presence of myocardial ischemia. Methods 2D short-axis or 3D full-volume images were acquired by Artida at baseline, during flow-limiting stenosis (mean 50±20% flow reduction), and during complete occlusion of the left circumflex coronary artery in 22 dogs (2D-STE = 12, 3D-STE = 10).Circumferential strain was analyzed in the center of risk area, and the absolute value of peak systolic strain (ε-sys), post-systolic strain index (PSI) as a parameter of PSS, and early systolic strain index (ESI) as a parameter of ESL were measured. A new parameter, myocardial dysfunction index (MDI), which was calculated as follows: (ESL amplitude + PSS amplitude)/maximal strain amplitude during the cardiac cycle, was also calculated. The difference in ε-sys between at baseline and during ischemia (Δε-sys) was measured and the diagnostic accuracy for estimating Δε-sys &lt; −3% was assessed by the receiver operating characteristics (ROC) curve analysis. Results During ischemia, ε-sys decreased from 19±3 to 12±6% and MDI increased from 2±4 to 27±30%. MDI was significantly correlated with Δε-sys (2D-STE: r=−0.80, 3D-STE: r=−0.83, p&lt;0.01, respectively) (Figure). The area under the curve (AUC) of MDI for estimating Δε-sys &lt; −3% tended to be larger than those of ESI and PSI (MDI: 0.9, ESI: 0.73, PSI: 0.85). Figure 1 Conclusions The novel parameter, MDI was correlated with the decrease in ε-sys during acute ischemia. Integrated analysis of ESL and PSS may be useful for diagnosing the presence of myocardial ischemia.

Accurate identification of myocardial viability after myocardial infarction with novel manganese chelate-based MR imaging.

We developed a novel manganese (Mn2+ ) chelate for magnetic resonance imaging (MRI) assessment of myocardial viability in acute and chronic myocardial infarct (MI) models, and compared it with Gadolinium-based delay enhancement MRI (Gd3+ -DEMRI) and histology. MI was induced in 14 rabbits by permanent occlusion of the left circumflex coronary artery. Gd3+ -DEMRI and Mn2+ chelate-based delayed enhancement MRI (Mn2+ chelate-DEMRI) were performed at 7days (acute MI, n=8) or 8weeks (chronic MI, n=6) after surgery with sequential injection of 0.15mmol/kg Gd3+ and Mn2+ chelate. The biodistribution of Mn2+ in tissues and blood was measured at 1.5 and 24h. Blood pressure, heart rate (HR), left ventricular (LV) function, and infarct fraction (IF) were analyzed, and IF was compared with the histology. The Mn2+ chelate group maintained a stable hemodynamic status during experiment. For acute and chronic MI, all rabbits survived without significant differences in HR or LV function before and after injection of Mn2+ chelate or Gd3+ (p>0.05). Mn2+ chelate mainly accumulated in the kidney, liver, spleen, and heart at 1.5h, with low tissue uptake and urine residue at 24h after injection. In the acute MI group, there was no significant difference in IF between Mn2+ chelate-DEMRI and histology (22.92±2.21% vs. 21.79±2.25%, respectively, p=0.87), while Gd3+ -DEMRI overestimated IF, as compared with histology (24.54±1.73%, p=0.04). In the chronic MI group, there was no significant difference in IF between the Mn2+ chelate-DEMRI, Gd3+ -DEMRI, and histology (29.50±11.39%, 29.95±9.40%, and 29.00±10.44%, respectively, p>0.05), and all three were well correlated (r=0.92-0.96, p<0.01). We conclude that the use of Mn2+ chelate-DEMRI is reliable for MI visualization and identifies acute MI more accurately than Gd3+ -DEMRI.

Preventive Melatonin Administration Decreased Dispersion of Repolarization and Myocardium Susceptibility to Ventricular Tachyarrhythmias in a Model of Acute Coronary Occlusion in Rabbits

IntroductionMelatonin is known to have a spectrum of antioxidative and cardioprotective properties, which may be beneficial in ischemia/reperfusion conditions, but a mechanism of its antiarrhythmic effects remains to be established. This study aimed to assess effects of preventive melatonin treatment on spatiotemporal ventricular electrophysiological parameters and susceptibility of myocardium to ventricular tachycardia and/or ventricular fibrillation (VT/VF) in an experimental model of acute ischemia/reperfusion in rabbits.MethodsExperiments were performed in 28 anesthetized open‐chest rabbits. Melatonin (10 mg/kg, i.v.) was administrated to the animals (n = 5) one hour before coronary occlusion, whereas the control rabbits (n = 23) received placebo. Unipolar electrograms were recorded with 64‐electrodes epicardial sock connected to a custom‐designed high resolution system (4 kHz) in a baseline state, at 15 min of the left circumflex coronary artery occlusion and after subsequent 15‐min reperfusion. Activation times and repolarization times (RTs) were measured in each lead as dV/dt minimum during QRS complex and dV/dt maximum during T wave, respectively. A border dispersion of repolarization (DOR) was measured as a difference between the minimal and maximal RTs of ischemic and border zone. The VT/VF susceptibility was tested by high frequency stimulation.ResultsMelatonin administration did not change baseline spatiotemporal activation and repolarization parameters. Median RTs were shortened in the ischemic zone at 15 min of coronary occlusion as compared to baseline (control: 90 [IQR 77–109] vs 148 [IQR 112–174] ms, p&lt;0.05; melatonin: 111 [IQR 108–117] vs 158 [IQR 155–160] ms, p&lt;0.05, respectively], with the “ischemic” RTs being significantly longer in the melatonin group (p = 0.038). At 15 min of reperfusion, the melatonin group demonstrated partial restoration of RTs (132 [IQR 123–140] ms), which was not observed in the control group (102 [IQR 95–126] ms, p = 0.044 vs melatonin group). Thus, the border DOR was greater in the control group as compared to the melatonin group at 15 min of ischemia (42 [IQR 21–47] ms vs 21 [IQR 16–21] ms, p = 0.043, respectively) and at 15 min of reperfusion (19 [IQR 8–33] ms vs 7 [IQR 1–8] ms, p = 0.038, respectively). In ischemia the melatonin‐treated animals demonstrated a lower arrhythmia susceptibility (0 vs 13 VT/VF episodes, p = 0.022, respectively).ConclusionIn the rabbit model of acute coronary occlusion/reperfusion, the melatonin‐related mitigation of VT/VF susceptibility was associated with the limitation of repolarization shortening in ischemic zone and decrease of DOR.Support or Funding InformationThe study was supported by Russian Science Foundation (RSF 18‐15‐00309).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.