Effects of primary PCI and facilitated PCI on myocardial viability and ventricular systolic synchrony in acute myocardial infarction patients

Objective To evaluate short time effects of primary percutaneous coronary intervention (pPCI) and rtPA thrombolysis+PCI (rtPA+PCI) on myocardial viability and ventricular systolic synchrony in AMI patients.Methods Eighty seven patients with first AMI were divided into two groups: group A ( n =42), pPCI group, the patients underwent PCI within 6h after onset of AMI; group B ( n =45), rtPA+PCI group, the patients underwent PCI after thrombolysis within 6h after onset of AMI; Myocardial viability was measured by 99m Tc MIBI SPECT. While, the parameters of cardiac function LVEF and ventricular systolic synchrony LVPS were measured by 99m Tc gated cardiac blood pool image on the first and the fourth weekend. Results (1) The peak CK MB was significantly lower in group A than that in group B( P <0.01 ). (2) Myocardial infarction area (MIA) was decreased and radioactivity counts in MIA was significantly increased in group A and B on the 4th weekend compared with that on the first weekend ( P <0.01 ), but there were no significant difference between group A and group B. (3) LVEF, LVPS were no significant difference between group A and group B.Conclusions (1)pPCI in acute myocardial infartion can limit infarct area, maintain ventricular systolic synchrony and improve ventricular function; (2) but, in those hospitals that there were no any condition for PCI, they should transfer the patients to central hospital for PCI after thrombolysis at the first time. It is beneficial to improve myocardial viability and ventricular systolic synchrony of AMI patients in short time.

An Experimental Study of Myocardial Viability with Myocardial Contrast Echocardiography

Background Myocardial blood flow(MBF) can be quantified with myocardial contrast echocardiography (MCE) during a venous infusion of microbubble. A minimal MBF is required to maintain cell membrane integrity and myocardial viability in ischemic condition. Thus, we hypothesized that MCE could be used to assess myocardial viability by the determination of MBF. Methods and ResultsMCE was performed at 4 hours after ligation of proximal left anterior descending coronary artery in 7 dogs with constant venous infusions of microbubbles. The video intensity versus pulsing interval plots derived from each myocardial pixel were fitted to an exponential function: y=A(1-e-βt), where y is Ⅵ at pulsing interval t, A reflects microvascular cross - sectional area (or myocardial blood volume), and βreflects mean myocardial microbubble velocity. The product of A·β represents MBF. MBF was also obtained by ra-diolabeled microsphere method servered as reference. MBF derived by radiolabeled microsphere - method in the regions of normal, ischemia and infarction was 1.5+0.3, 0.7+0.3, 0. 3+0. 2 mL @ min-1@ g-1 respectively. The product of A·β obtained by MCE in those regions was 52. 46±15. 09, 24. 36±3. 89, 3. 74 ±3. 80 respectively. There was good correlation between normalized MBF and the normalized A·β ( r = 0. 81, P=0. 001). Conclusions MCE has an ability to determine myocardial viability in myocardial infarction canine model.

Evaluation of myocardial viability during cold storage by measurement of myocardual dielectric properties tanδm in radio frequency

Objective To study the mechanism of myocardial dielectric property changes in radio frequency during hypothermic preservation and explore myocardial viability evaluative method. Methods Hybrid young pigs ( 20 - 30 kg) were used in the experiment. Heart arrest was in-

Magnetic resonance imaging and multi-detector computed tomography assessment of extracellular compartment in ischemic and non-ischemic myocardial pathologies

Myocardial pathologies are major causes of morbidity and mortality worldwide. Early detection of loss of cellular integrity and expansion in extracellular volume(ECV) in myocardium is critical to initiate effective treatment. The three compartments in healthy myocardium are: intravascular(approximately 10% of tissue volume), interstitium(approximately 15%) and intracellular(approximately 75%). Myocardial cells, fibroblasts and vascular endothelial/smooth muscle cells represent intracellular compartment and the main proteins in the interstitium are types Ⅰ/Ⅲ collagens. Microscopic studies have shown that expansion of ECV is an important feature of diffuse physiologic fibrosis(e.g., aging and obesity) and pathologic fibrosis [heart failure, aortic valve disease, hypertrophic cardiomyopathy, myocarditis, dilated cardiomyopathy, amyloidosis, congenital heart disease, aortic stenosis, restrictive cardiomyopathy(hypereosinophilic and idiopathic types), arrythmogenic right ventricular dysplasia and hypertension]. This review addresses recent advances in measuring of ECV in ischemic and non-ischemic myocardial pathologies. Magnetic resonance imaging(MRI) has the ability to characterize tissue proton relaxation times(T1, T2, and T2*). Proton relaxation times reflect the physical and chemical environments of water protons in myocardium. Delayed contrast enhanced-MRI(DE-MRI) and multi-detector computed tomography(DE-MDCT) demonstrated hyper-enhanced infarct, hypo-enhanced microvascular obstruction zone and moderately enhanced peri-infarct zone, but are limited for visualizing diffuse fibrosis and patchy microinfarct despite the increase in ECV. ECV can be measured on equilibrium contrast enhanced MRI/MDCT and MRI longitudinal relaxation time mapping. Equilibrium contrast enhanced MRI/MDCT and MRI T1 mapping is currently used, but at a lower scale, as an alternative to invasive sub-endomyocardial biopsies to eliminate the need for anesthesia, coronary catheterization and possibility of tissue sampling error. Similar to delayed contrast enhancement, equilibrium contrast enhanced MRI/MDCT and T1 mapping is completely noninvasive and may play a specialized role in diagnosis of subclinical and other myocardial pathologies. DE-MRI and when T1-mapping demonstrated sub-epicardium, sub-endocardial and patchy mid-myocardial enhancement in myocarditis, Behcet's disease and sarcoidosis, respectively. Furthermore, recent studies showed that the combined technique of cine, T2-weighted and DE-MRI technique has high diagnostic accuracy for detecting myocarditis. When the tomographic techniques are coupled with myocardial perfusion and left ventricular function they can provide valuable information on the progression of myocardial pathologies and effectiveness of new therapies.

Detection of Ischemic Myocardium with a New Hypoxic Tissue Targeting Tracer ^99Tc^m-HL91

The imaging appearances of ^99Tc^m-HL91, a new hypoxic imaging agent, in ischemic myocardium were studied and the value of ^99Tc^m-HL91 in the evaluation of regional ischemic viable myocardium was explored. Acute myocardial ischemia models were made by coronary artery legations in 18 rats and randomly divided into 2 groups： ^99Tc^m-HL91 group and ^99Tc^m-MIBI group. Evan blue infusion during ischemia and TTC staining after operation were used to delineate the area of ischemic and viable myocardium. The isolated heart was sliced in the short axis and then autoradiography was performed,. The electron microscopic examination was also done for the myocardial sampies. ^99Tc^m-HL91 and ^99Tc^m-MIBI uptake activities （counts/g） were measured in the area of ischemic myocardium （T） and normal myocardium （NT） separately. The uptake ratios ^99Tc^m-HL91 and that of ^99Tc^m-MIBI in ischemic myocardium were calculated as T/NT. It was found that the normal myocardium was blue and ischemic or infarct myocardium was negative with Evans blue in all experiment rats. Both the normal and ischemic myocardium was in red color with TTC staining. In the ^99Tc^m-HL91 group the ischemic myocardium showed much higher uptake over normal myocardium, that was demonstrated both in the autoradiography and quantitative analysis. The ischemic/normal activity ratios were 1. 634 ± 0. 354. It was suggested that ^99Tc^m-HL91 might accumulate in ischemic and viable myocardium, which is helpful in the evaluation of hypoxic but viable myocardium and potentially used as a imaging agent to assess myocardial viability.

Magnetic susceptibility of Dy-DTPA-BMA to reperfused myocardial infarction in an excised dog heart model: evidence of viable myocardium

Objective To assess the effects of Dy DTPA BMA (sprodiamide) on ex vivo MR imaging of reperfused acute myocardial infarction Methods Eighteen dogs were subjected to 2 hour coronary artery occlusion followed by 24 hour reperfusion Dysprosium chelate (Dy DTPA BMA) was injected into 16 dogs Twenty minutes before their sacrifice Two dogs did not receive the contrast medium and were used as controls Excised hearts were imaged on T2 weighted spin echo sequence (T2W SE) and T2 * weighted gradient recalled echo sequence (T2 *W GRE), then sectioned and double perfused for planimetric comparison Results Dy DTPA BMA induced myocardial signal loss was detected on T2W SE and on T2 *W GRE images The signal loss was observed at the subendocardial location of the myocardial wall inducing an apparent enlargement of the left ventricle cavity and a thinning appearance of the anterior myocardial wall Conclusions Myocyte necrosis diminishes the potency of dysprosium to cause MR imaging signal intensity loss in reperfused myocardial infarction Pre infarcted myocardium with potentially reversible viability may be responsible for the effect of the contrast medium

Impact of Coronary Chronic Total Occlusion on Long-term Clinical Outcome in Patients with Unprotected Left Main Disease Undergoing Percutaneous Coronary Intervention

Objectives:Reported data regarding the prevalence,prognostic impact,and safety and efficacy of revascularization of coronary chronic total occlusion(CTO)in patients with left main coronary artery(LMCA)disease who undergo percutaneous coronary intervention(PCI)are scarce.The aim of the present study was to compare clinical outcomes among patients with LMCA disease undergoing PCI.Outcomes were compared between those with and without coronary CTO and between those with CTO who had successful and unsuccessful CTO recanalization procedures.Methods:All consecutive patients with significant LMCA disease(>50%stenosis at coronary angiography)who underwent PCI between July 2014 and December 2018 were retrospectively included in our study.The primary endpoint of the study was long-term mortality.Secondary endpoints included the incidence of myocardial infarction,repeat percutaneous or surgical revascularization,stroke,and stent thrombosis.Results:Between July 2014 and December 2018,578 patients underwent PCI for LMCA disease at Pederzoli Hospital and University of Turin were enrolled.They were divided into 3 groups:group A:374(65%)patients without CTO,group B:108(19%)patients with untreated or unsuccessfully treated CTO,and group C:96(17%)patients with successfully treated CTO.At a median follow-up of(1090±279)days,there were no statistically significant differences between the groups in terms of the primary and secondary endpoints.However,there was a trend towards higher mortality in patients with untreated or unsuccessfully treated CTO(13%vs.19%vs.14%in groups A,B,and C,respectively;P=0.12).The primary and secondary endpoints were further analyzed based on the presence or absence of myocardial viability:subgroup C1:54(56%)patients with successful percutaneous transluminal coronary angioplasty(PTCA)having viability,and subgroup C2:42(44%)patients with successful PTCA not having viability.There was a trend toward a statistically significant higher rate of death among patients in group B,who underwent unsuccessful recanalization with viable myocardium(19%vs.9%vs.19%in groups B,C1,and C2,respectively,P=0.05).On multivariable analysis,the propensity for successful revascularization of CTO was associated with a reduced risk of death(P=0.01;odds ratio,0.75;95%confidence interval:0.62-0.87).Conclusions:Among patients with LMCA disease undergoing PCI,CTO represents a common finding associated with worse prognosis.Successful revascularization of CTO in patients with viable myocardium appears to significantly improve prognosis.