Regional Myocardial Perfusion Research Articles

Absolute coronary flow and microvascular resistance before and after TAVR

Abstract Purpose This study aims to investigate microcirculatory changes, both at rest and during hyperemia, using continuous intracoronary thermodilution, before TAVR, immediately post-TAVR, and at 6-month follow-up. Methods We included consecutive patients with high-gradient AS undergoing TAVR with non-obstructive coronary artery disease in the left anterior descending artery (LAD). Absolute coronary flow (Q) and microvascular resistance (R) were measured in the LAD using continuous intracoronary thermodilution at rest (Qrest) and during hyperemia (Qhyper) before and after TAVR, as well as at 6-month follow-up. Echocardiography and cardiac computed tomography (CCT) were used to quantify total myocardial mass and LAD-specific mass. Regional myocardial perfusion (QN) was calculated by dividing absolute coronary flow by the subtended myocardial mass. Results In 51 patients, absolute flow and microvascular resistance were assessed at rest and during hyperemia before and after TAVR. The mean age was 84.1 ± 5.0 years, and 35 participants were male (68.6%). Measurements were also obtained 6 months after TAVR in 20 (39%) patients. Overall, there were no significant changes in resting and hyperemic flow and resistance before and after TAVR (Qrest 68 [55-88] mL/min vs 69 [54 – 92] mL/min, p=0.776; Qhyper 158 [129 – 200] mL/min vs 172 [132, 216] mL/min, p=0.449, before and after TAVR, respectively). Consequently, coronary flow reserve (CFR) and microvascular resistance reserve (MRR) remained unchanged. At 6 months, there were no significant changes in flow and resistance both at rest and during hyperemia compared to baseline (Qrest: 72 [63-84] vs 83 [59-108] mL/min, p=0.658; Qhyper: 181 [158-200] vs 194 [167-222] mL/min, p=0.492; pre-TAVR and at 6 months follow-up, respectively), resulting in unchanged CFR and MRR. However, at follow-up, there was a noteworthy reduction in left ventricular mass of approximately 13% (from 201.9 ± 37.9g to 175.1 ± 46.6 g, p<0.001), leading to an increase in hyperemic perfusion (QN,hyper: 0.86 [0.69-1.06] vs 1.20 [0.99-1.32] mL/min/g, p=0.008; pre-TAVR and follow-up, respectively), but not in resting perfusion (QN, rest: 0.34 [0.30-0.48] vs 0.47 [0.36-0.67] mL/min/g, p=0.06). Conclusion Immediately after TAVR, there are no changes in absolute coronary flow and coronary flow reserve. Over time, LV remodeling is associated with increased hyperemic perfusion, indicating that, in the context of the observed pathophysiological changes in coronary microcirculation in AS patients after TAVR, the reverse LV remodeling has a more significant impact than the acute LV unloading achieved by valve replacement itself.

Regional distribution of diffuse fibrosis in the basal and mid-ventricular AHA segments in patients with type 2 diabetes

Abstract Introduction Cardiovascular magnetic resonance (CMR) research including from our research group, has documented that patients (pts.) with type 2 diabetes (DM2) even without symptoms exhibit subtle to moderately increased myocardial extracellular volume (ECV). ECV is an imaging biomarker of diffuse fibrosis. Also, our prior research has revealed a prevalence of approx. 10% for non-ischemic late gadolinium enhancement (LGE). Intriguingly, these LGE lesions manifested in a distinct pattern, situated in the basal lateral or infero-lateral positions. We postulate that these lesions may represent the end-stage of severe diffuse fibrosis, potentially influenced by factors such as increased shear wall stress. Purpose To investigate if pts. with DM2 with known high global ECV had higher regional ECV in the basal and lateral or infero-lateral AHA segments compared to other segments. Method A case-control study of 20 healthy controls, 20 pts. with DM2 with low ECV (ECV<28%), 20 pts. with DM2 with high ECV (ECV>29%), and 20 pts. with DM2 with non-ischemic LGE (LGE+). Pts. were identified from a cross-sectional cohort of pts. with DM2. All subjects underwent physical examination and extensive CMR with T1 mapping before and after gadolinium contrast, and myocardial perfusion at rest and during adenosine stress. The regional ECV values for the basal and the mid-ventricular short axis slide were analysed using the AHA segments model: segments 1 to 12. Results All groups (grp.) had comparable age and sex distribution. In the DM2 grp. there was a difference between the no. of pts. with DM2 duration >10 years (low ECV 11(55%), high ECV 12(60%), LGE+ 16(80%), however statistically significant. Global ECV were: Controls (mean±sd) 26.7±1.6%, Low ECV 26.3±1.4%, High ECV 32.0±2.9%, LGE+ 29.5±2.6%, p<0.001. Control subjects had regional ECV between 24.4±2% to 27.3±2% (p<0.001), highest values in the septum. The DM2 grp. with low ECV had regional ECV values of 24.5±3% to 29.2±4%, highest values in the basal inferior and septal parts (segments 2-4). The high ECV grp. had regional ECV values between 28.3±4% and 35.3±6 % with very high values in the basal and the mid-ventricular septum, inferior, and inferolateral part (segments 2-5 and 8-11). The DM2 group LGE+ had values between 26.6±3% and 34.5±7%, highest values in the basal slice in the septum, inferior, and infero-lateral parts (segments 2-5). We found no significant difference in the regional myocardial perfusion reserve index. Conclusion This evidence indicates that diffuse fibrosis in DM2 cardiomyopathy tends to concentrate in the septum and inferolateral regions. However, among pts. with non-ischemic LGE lesions, we observed normal ECV in the anterior segments, in contrast to the high ECV group where all segments exceeded normal levels, albeit with notable regional variations. Subsequent investigations should prioritize uncovering the underlying reasons for this specific regional distribution of diffuse fibrosis.AHA segments 1-12 mapsAHA segments 1-12 maps

Absolute coronary flow and microvascular resistance before and after transcatheter aortic valve implantation.

Severe aortic stenosis (AS) is associated with left ventricular (LV) remodelling, likely causing alterations in coronary blood flow and microvascular resistance. We aimed to evaluate changes in absolute coronary flow and microvascular resistance in patients with AS undergoing transcatheter aortic valve implantation (TAVI). Consecutive patients with AS undergoing TAVI with non-obstructive coronary artery disease in the left anterior descending artery (LAD) were included. Absolute coronary flow (Q) and microvascular resistance (Rμ) were measured in the LAD using continuous intracoronary thermodilution at rest and during hyperaemia before and after TAVI, and at 6-month follow-up. Total myocardial mass and LAD-specific mass were quantified by echocardiography and cardiac computed tomography. Regional myocardial perfusion (QN) was calculated by dividing absolute flow by the subtended myocardial mass. In 51 patients, Q and R were measured at rest and during hyperaemia before and after TAVI; in 20 (39%) patients, measurements were also obtained 6 months after TAVI. No changes occurred in resting and hyperaemic flow and resistance before and after TAVI nor after 6 months. However, at 6-month follow-up, a notable reverse LV remodelling resulted in a significant increase in hyperaemic perfusion (QN,hyper: 0.86 [interquartile range {IQR} 0.691.06] vs 1.20 [IQR 0.99-1.32] mL/min/g; p=0.008; pre-TAVI and follow-up, respectively) but not in resting perfusion (QN,rest: 0.34 [IQR 0.30-0.48] vs 0.47 [IQR 0.36-0.67] mL/min/g; p=0.06). Immediately after TAVI, no changes occurred in absolute coronary flow or coronary flow reserve. Over time, the remodelling of the left ventricle is associated with increased hyperaemic perfusion.

Validation of resting full-cycle ratio and diastolic pressure ratio with [15O]H2O positron emission tomography myocardial perfusion

Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are invasive techniques used to evaluate the hemodynamic significance of coronary artery stenosis. These methods have been validated through perfusion imaging and clinical trials. New invasive pressure ratios that do not require hyperemia have recently emerged, and it is essential to confirm their diagnostic efficacy. The aim of this study was to validate the resting full-cycle ratio (RFR) and the diastolic pressure ratio (dPR), against [15O]H2O positron emission tomography (PET) imaging. A total of 129 symptomatic patients with an intermediate risk of coronary artery disease (CAD) were included. All patients underwent cardiac [15O]H2O PET with quantitative assessment of resting and hyperemic myocardial perfusion. Within a 2 week period, coronary angiography was performed. Intracoronary pressure measurements were obtained in 320 vessels and RFR, dPR, and FFR were computed. PET derived regional hyperemic myocardial blood flow (hMBF) and myocardial perfusion reserve (MPR) served as reference standards. In coronary arteries with stenoses (43%, 136 of 320), the overall diagnostic accuracies of RFR, dPR, and FFR did not differ when PET hyperemic MBF < 2.3 ml min−1 (69.9%, 70.6%, and 77.1%, respectively) and PET MPR < 2.5 (70.6%, 71.3%, and 66.9%, respectively) were considered as the reference for myocardial ischemia. Non-significant differences between the areas under the receiver operating characteristic (ROC) curve were found between the different indices. Furthermore, the integration of FFR with RFR (or dPR) does not enhance the diagnostic information already achieved by FFR in the characterization of ischemia via PET perfusion. In conclusion, the novel non-hyperemic pressure ratios, RFR and dPR, have a diagnostic performance comparable to FFR in assessing regional myocardial ischemia. These findings suggest that RFR and dPR may be considered as an FFR alternative for invasively guiding revascularization treatment in symptomatic patients with CAD.

Ultrasound study of right ventricular myocardial perfusion and functional changes in hypertrophic cardiomyopathy.

To evaluate the changes of right ventricular (RV) myocardial perfusion and function in patients with hypertrophic cardiomyopathy (HCM) by myocardial contrast echocardiography (MCE) and speckle tracking (2D-STE), and to explore the relationship between RV myocardial perfusion and strain. Conventional ultrasound, MCE and 2D-STE were performed on 29 HCM patients and 21 healthy subjects to analyze RV myocardial perfusion, RV global strain, RV free wall strain, and strain of each segment. The correlation between RV myocardial perfusion and strain was further analyzed in HCM patients. MCE results showed that the regional myocardial perfusion of the RV in HCM patients was decreased. Compared with the normal control group, the mean slope (β) in the middle and apical segments of the RV free wall, and the peak intensity (A), β, myocardial blood flow (MBF) of the ventricular septum decreased in HCM patients (P < 0.05). RV function was impaired in HCM patients. The RV global strain (RV GLS), and the strain of RV free wall and each segment were lower than those in the normal control group (P < 0.05). Correlation analysis showed that there was a certain correlation between RV myocardial perfusion and strain, such as the β of the whole RV in HCM group had a positive correlation with the strain of the middle segment of the interventricular septum (r = 0.550, P = 0.002). The regional myocardial perfusion and strain of the RV in HCM patients are reduced, and there is a positive correlation between them, suggesting that the reduction of myocardial strain may be related to the impairment of myocardial microcirculation.

Association between resting myocardial work indices and stress myocardial perfusion in patients with angina and non-obstructive coronary artery disease.

Myocardial work (MW) indices and longitudinal strain (LS) are sensitive markers of early left ventricular systolic dysfunction. Stress computed tomography myocardial perfusion imaging (CT-MPI) can assess early myocardial ischemia. The association between resting MW indices and stress myocardial perfusion remains unclear. This study compares resting MW indices with LS to assess stress myocardial perfusion in angina patients with non-obstructive coronary artery disease (CAD). Eighty-four patients who underwent resting echocardiography, coronary computed tomography angiography, and stress CT-MPI were reviewed. Seventeen myocardial segments were divided into three regions according to the epicardial coronary arteries. Global indices included global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). Regional indices included regional longitudinal strain (RLS), regional work index (RWI), and regional work efficiency (RWE). Reduced global perfusion was defined as an average stress myocardial blood flow (MBF) <116 mL/100 mL/min for the whole heart. Reduced regional perfusion was defined as an average stress MBF <116 mL/100 mL/min for the coronary territories. No patients demonstrated obstructions in the epicardial coronary arteries (stenosis diameter <50%). The MW indices and LS were compared. Receiver operating characteristic curves were constructed and logistic regression analyses were used to investigate the predictors of reduced myocardial perfusion. Patients with reduced stress perfusion demonstrated reduced GLS, GWI, GCW, and GWE (P<0.05) and increased GWW (P<0.05). After adjustment for age and sex, GWE was still independently associated with reduced myocardial perfusion (odds ratio =0.386, 95% confidence interval: 0.214-0.697; P<0.05). Receiver operating characteristic curves reflected the good diagnostic ability of GWE and its superiority to GLS (area under the curve: 0.858 vs. 0.741). The optimal cutoff GWE value was 95% (sensitivity, 70%; specificity, 90%). Regions with lower stress perfusion showed lower RLS, RWI, and RWE (P<0.05). The optimal cutoff value of RWE for predicting reduced regional perfusion was 95%, with an area under the curve of 0.780, a sensitivity of 62%, and a specificity of 83%. Resting MW indices perform well in assessing global and regional stress myocardial perfusion in angina patients with non-obstructive CAD, and GWE is superior to GLS in the global evaluations.

Historical review of development of indirect methods of myocardial revascularization

The article presents a historical review. For several decades, the diseases of the circulatory system have remained one of the most pressing problems of mankind. However, in the recent years there has been a tendency to decrease in mortality from cardiovascular pathologies including coronary heart disease. At the dawn of the study of coronary artery disease, the problem of surgical treatment of coronary artery pathology looked practically unsolvable: there was no knowledge of pathophysiology, no microsurgical instruments, and artificial circulation apparatus. Among other things, the stereotype of the "inviolability" of the heart muscle firmly entrenched in the minds of operating surgeons. A safe operation on a human heart was only a dream and the object of ridicule among most surgeons of the XIX early XX centuries. The article describes the history of the study of angina pectoris and indirect methods of myocardial revascularization. The first operations were aimed at eliminating pain syndrome and inducing angiogenesis, creating neocollaterals from blood vessel-rich organs and tissues to improve regional myocardial perfusion. Exactly these surgical techniques have become a "bridge" from the tactics of exclusively conservative management of heart pathologies to modern cardiac surgery.

Changes in myocardial perfusion according to left ventricular pacing site in cardiac resynchronization therapy

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): 1. The Danish Heart Foundation 2. The Health Research Fund of the Central Denmark Region Background/Introduction Changes in left ventricular (LV) myocardial perfusion according to LV pacing site during cardiac resynchronization therapy (CRT) has only been sparsely described. Purpose To assess changes in LV global and regional myocardial perfusion according to LV pacing site after six months CRT. Methods Data from patients enrolled in the randomized controlled trial "Electrically vs. Imaging-guided Left Ventricular Lead Placement in Cardiac Resynchronization Therapy" was evaluated. Global and segmental absolute myocardial perfusion in ml/g/min was assessed by 82Rb-PET the day before CRT implantation and at six-months follow-up (6MFU). The exact LV pacing site was determined by post-implant cardiac CT. Perfusion and pacing site were evaluated using the standard 17’-segment LV model. Echocardiographic assessment of LV ejection fraction (EF) was performed the day before CRT implantation and at 6MFU. Results 93 patients (age 71±9 years; ischemic heart disease 48%; female 25%; median QRS 166±20 ms; mean LVEF 30±7%; NYHA class I/II/III/IV (%) 0/63/33/3) were included. Distribution of LV pacing sites is shown in Figure 1. No change in LV global perfusion was observed from baseline to 6MFU (0.79 to 0.81 ml/g/min, P=0.41; respectively). LV EF increased by 9±10%. Baseline global perfusion was higher in the 39 patients in whom LV EF had increased ≥10% at 6MFU (0.86 vs. 0.74 ml/g/min, P=0.02; respectively). However, no difference in perfusion-change was observed between patients with ≥10% increase in LV EF at 6MFU and patients with &amp;lt;10% increase (0.01 vs. 0.02 ml/g/min, P=0.76; respectively). Baseline perfusion was higher in the segments chosen for LV-pacing than in the non-paced segments (0.96 vs. 0.78 ml/g/min, P=0.00; respectively). Perfusion in the paced segments dropped to 0.86 ml/g/min (P=0.00) at 6MFU. Perfusion in the neighbouring segments also dropped during six months (from 0.91 to 0.86 ml/g/min, P=0.03), while perfusion in the non-paced and non-neighbouring segments increased (from 0.75 to 0.80 ml/g/min, P=0.01). Conclusion Despite a mean increase in LV EF of 9%, global myocardial perfusion remained unchanged. CRT resulted in a homogenous distribution of myocardial perfusion with a decreased perfusion in segments concordant and adjacent to LV pacing site and a corresponding increased perfusion in remote segments.

Deep Learning-Based Image Registration in Dynamic Myocardial Perfusion CT Imaging.

Registration of dynamic CT image sequences is a crucial preprocessing step for clinical evaluation of multiple physiological determinants in the heart such as global and regional myocardial perfusion. In this work, we present a deformable deep learning-based image registration method for quantitative myocardial perfusion CT examinations, which in contrast to previous approaches, takes into account some unique challenges such as low image quality with less accurate anatomical landmarks, dynamic changes of contrast agent concentration in the heart chambers and tissue, and misalignment caused by cardiac stress, respiration, and patient motion. The introduced method uses a recursive cascade network with a ventricle segmentation module, and a novel loss function that accounts for local contrast changes over time. It was trained and validated on a dataset of n = 118 patients with known or suspected coronary artery disease and/or aortic valve insufficiency. Our results demonstrate that the proposed method is capable of registering dynamic cardiac perfusion sequences by reducing local tissue displacements of the left ventricle (LV), whereas contrast changes do not affect the registration and image quality, in particular the absolute CT (HU) values of the entire CT sequence. In addition, the deep learning-based approach presented reveals a short processing time of a few seconds compared to conventional image registration methods, demonstrating its application potential for quantitative CT myocardial perfusion measurements in daily clinical routine.

ASSESSMENT OF PATIENTS WITH KNOWN CORONARY ARTERY DISEASE BY STRESS CARDIAC MRI.

Background: Signicant coronary artery lesions can be detected by evaluating regional myocardial perfusion by Cardiac MRI (CMR). This study aims to determine the usefulness of this technique in “known” patients of coronary artery disease (CAD). Our study aims at describing CMR featur Methods: es of CAD, including CINE and perfusion imaging. Stress perfusion imaging with pharmacologic stress (Adenosine) was performed on 22 patients with known CAD. These patients also underwent Catheter angiography (CAG). A total of 66 coronary territories were assessed for perfusion abnormalities and corresponding CAG ndings. Regional wall motion abnormalities were Results: seen in 28(42.4%) coronary territories and regional myocardial thinning in 11(16%) territories. Hypokinesia (68%) was the most commonly observed wall motion abnormality. Wall motion abnormality was present in most (91%; n=20) of the infarcted territories and some (18.2%;n=8) of the non-infarct territories. Regional myocardial thinning was present in some of the infarcted (27%; n=6) territories and none of the non-infarcted territories. The mean wall thickness in infarct territories was 5.1mm±0.4 and in non-infarct territories was 7.1mm±0.6. T2/STIR hyperintensity was present in 5 (23%) infarct related coronary territories and none of the non-infarcted territories. In all 5 cases, MRI was done within 10 days of symptom onset. 32 (49%) coronary territories showed perfusion defect on stress imaging, with 23 (35%) of them showing a matched defect on rest perfusion and 9 (14%) showing stress inducible perfusion defect. No perfusion defect was seen in 34(51%) territories. All 22 patients underwent CAG. 15patients had signicant disease (&gt;70%) in a single vessel, 5 had in two vessels and none had in all the three vessels.2 patients had non-occlusive coronaries (MINOCA). Using CAG as gold standard, the sensitivity of stress perfusion CMR in detecting signicant CAD in non-infarct territory in these patients was 70%, with a specicity of 94% and accuracy of 88.3%. Visual analysis of rst-pass gadolinium CMR perfusion images to detect reg Conclusion: ional myocardial perfusion defect has a moderate sensitivity and high specicity for diagnosing signicant obstructive CAD in non-infarct related coronaries, as compared to CAG.

Coronary conductance in the normal development of sheep during the perinatal period.

Birth is associated with substantial shifts in cardiovascular physiology. Little is known about coronary vascular adaptations during this period. We used fetal and neonatal lambs to measure coronary function at late gestation (92% of term) and shortly after birth (5-6 days postnatal age). In each animal we measured unanesthetized myocardial perfusion and oxygen delivery using a circumflex artery flow probe. We used inflatable occluders and adenosine to determine coronary conductance and flow reserve. In a subset of animals, we used myocardial contrast echocardiography (MCE, anesthetized) to assess its utility as a tool for studying changes in regional myocardial perfusion in normal development. Separate age-matched animals were instrumented with aortic and coronary sinus sampling catheters to determine myocardial oxygen extraction (unanesthetized). With an average of 17 days of developmental time separating our neonatal and fetal cohorts we found that heart-to-body weight ratio was significantly greater in neonates than fetuses. In resting animals, we found significant decreases in weight-normalized perfusion of, and oxygen delivery to, neonatal relative to fetal myocardium. Similar results were seen when measuring baseline MCE-derived perfusion. Pressure-flow relationship studies revealed lower baseline and maximal coronary conductance in neonates than fetuses, with similar coronary flow reserve between groups. There was greater oxygen extraction in neonates than fetuses. Combined analysis of oxygen extraction with coronary flow suggested greater oxygen consumption by the fetal than neonatal myocardium. We conclude that, during the immediate perinatal period, cardiac growth outpaces coronary microvascular growth resulting in lower capacity for microvascular perfusion in the early neonate.

Immediate impact of coronary artery bypass graft surgery on regional myocardial perfusion: Results from the Collaborative Pilot Study to Determine the Correlation Between Intraoperative Observations Using Spy Near-Infrared Imaging and Cardiac Catheterization Laboratory Physiological Assessment of Lesion Severity

ObjectivesCoronary artery bypass grafting (CABG) is performed using anatomic guidance. Data connecting the physiologic significance of the coronary vessel stenosis to the acute physiologic response to grafting are lacking. The Collaborative Pilot Study to Determine the Correlation Between Intraoperative Observations Using Spy Near-Infrared Imaging and Cardiac Catheterization Laboratory Physiological Assessment of Lesion Severity study is the first to compare preintervention coronary physiology with the acute regional myocardial perfusion change (RMP-QC) at CABG in a per-graft analysis. MethodsNon-emergent patients undergoing diagnostic catheterization suitable for multivessel CABG were enrolled. Synergy between Percutaneous Coronary Intervention with Taxus score, fractional flow reserve (FFR), instantaneous wave free ratio (iFR), and quantitative coronary angiography was documented in 75 epicardial coronary arteries, with 62 angiographically intermediate and 13 severe stenoses. At CABG, near-infrared fluorescence analysis quantified the relative change (post- vs pregrafting, termed RMP-QC) in the grafted vessel's perfusion territory. Scatter plots were constructed for RMP-QC versus quantitative coronary angiography and RMP-QC versus FFR/iFR. Exact quadrant randomization test for randomness was used. ResultsThere was no relationship between RMP-QC and quantitative coronary angiography percent diameter stenosis, whether all study vessels were included (P = .949) or vessels with core-lab quantitative coronary angiography only (P = .922). A significant nonrandom association between RMP-QC and FFR (P = .025), as well as between RMP-QC and iFR (P = .008), was documented. These associations remained when excluding vessels with assigned FFR and iFR values (P = .0092 and P = .0006 for FFR and iFR, respectively). ConclusionsThe Collaborative Pilot Study to Determine the Correlation Between Intraoperative Observations Using Spy Near-Infrared Imaging and Cardiac Catheterization Laboratory Physiological Assessment of Lesion Severity study demonstrates there is no association between angiographic coronary stenosis severity and the acute perfusion change after grafting; there is an association between functional stenosis severity and absolute increase in regional myocardial perfusion after CABG.

Regional myocardial perfusion imaging in predicting vessel-related outcome: interplay between the perfusion results and angiographic findings

BackgroundDespite myocardial perfusion imaging (MPI) by cadmium-zinc-telluride (CZT) single-photon emission computed tomography (SPECT) camera is largely used in the diagnosis and risk stratification of patients with suspected or known coronary artery disease (CAD), no data are available on the prognostic value of a regional MPI evaluation. We evaluated the prognostic value of regional MPI by the CZT camera in predicting clinical outcomes at the vessel level in patients with available angiographic data.Methods and resultsFive hundred and forty-one subjects with suspected or known CAD referred to 99mTc-sestamibi gated CZT-SPECT cardiac imaging and with available angiographic data were studied. Both regional total perfusion deficit (TPD) and ischemic TPD (ITPD) were calculated separately for each vascular territory (left anterior descending, left circumflex, and right coronary artery). The outcome end points were cardiac death, target vessel-related myocardial infarction, or late coronary revascularization. The prevalence of CAD ≥ 50%, regional stress TPD, and regional ITPD was significantly higher in vessels with events as compared to those without (both P < 0.001). The receiver operating characteristics area under the curve for regional ITPD for the identification of vessel-related events was 0.81 (95% confidence interval 0.75–0.86). An ITPD value of 2.0% provided the best trade-off for identifying the vessel-related event. At multivariable analysis, both CAD ≥ 50% and ITPD ≥ 2.0% resulted in independent predictors of events.ConclusionsRegional myocardial perfusion assessed by the CZT camera demonstrated good reliability in predicting vessel-related events in patients with suspected or known CAD.

Methodology and immediate results of selective controlled cerebral and myocardial perfusion for aortic arch obstruction in children

Highlights. Congenital heart defects in combination with aortic arch hypoplasia or coarctation of aorta are quite common in cardiac surgeon’s practice. The protection of internal organs is an important point in the treatment of these defects. Several methods have been proposed from hypothermic arrest to selective perfusion of various vascular regions. Given the variety of techniques, the effectiveness and advantages of each one are still a topic of debates. The article reflects the experience of using cerebro-myocardial perfusion in children with surgical correction of the aortic arch pathology.Aim. To analyze the prospects of regional selective controlled cerebral and myocardial perfusion method in surgical correction of aortic arch obstruction in children.Methods. A retrospective single-center analysis of the treatment in 29 pediatric patients was carried out and immediate results of cerebral-myocardial perfusion used in children with surgical correction of aortic arch obstruction in the period from 2016 to 2020 are presented. Median age was 6 days (1 day – 15 years old). Median weight was 3.6 kg (1.8–47 kg). 15 patients were girls, 14 patients were boys. The inclusion criteria for all the patients were cerebro-myocardial perfusion for aortic arch reconstruction.Results.Cardiopulmonary bypass time median was 78 minutes (43–206 minutes). The average time of cerebro-myocardial perfusion was 22.4 + –6.4 min (12–35 min). The median duration of the surgery was 3.1 hours (2.25–5.5 hours). The median time for mechanical ventilation was 101 hours (6–744 hours), in the ICU – 8.5 days (1–31 days). The average time of hospital stay was 18.2 days + –6.7 days (7–31 days). Early postoperative mortality was 3.4%. Renal replacement therapy was required for 2 newborns (7%). Operational risks, according to the Aristotle Score, were significantly higher in newborns (χ2 = 3.9277, df = 1, p-value = 0.0475). There were no cardiac events associated with myocardial perfusion. The type of cardioplegia (blood or “Kustadiol”) did not significantly affect the pumping function of the heart, assessed by transthoracic echocardiography on day 1 after the surgery (χ2 = 0.27273, df = 1, p-value = 0.6015). Acute ischemic cerebrovascular accident occurred in 1 patient (3.5%).Conclusion. The technique of controlled selective cerebro-myocardial perfusion is reproducible without any additional resource costs. We can confidently say that the time of surgery and cardiopulmonary bypass is much shorter than in case of using deep hypothermic arrest or isolated selective cerebral perfusion, as soon as there is less time needed for cooling and re-warming the body. Also, the time of cardiac arrest was reduced or completely eliminated (with isolated reconstruction of the aortic arch). The technique is effective and safely reproducible in both newborns and older children. The results for mortality and complications are encouraging but must be further evaluated and compared.

Multiscale model of the physiological control of myocardial perfusion to delineate putative metabolic feedback mechanisms.

Coronary blood flow is tightly regulated to ensure that myocardial oxygen delivery meets local metabolic demand via the concurrent action of myogenic, neural and metabolic mechanisms. Although several competing hypotheses exist, the specific nature of the local metabolic mechanism(s) remains poorly defined. To gain insights into the viability of putative metabolic feedback mechanisms and into the co-ordinated action of parallel regulatory mechanisms, we applied a multiscale modelling framework to analyse experimental data on coronary pressure, flow and myocardial oxygen delivery in the porcine heart in vivo. The modelling framework integrates a previously established lumped-parameter model of myocardial perfusion used to account for transmural haemodynamic variations and a simple vessel mechanics model used to simulate the vascular tone in each of three myocardial layers. Vascular tone in the resistance vessel mechanics model is governed by input stimuli from the myogenic, metabolic and autonomic control mechanisms. Seven competing formulations of the metabolic feedback mechanism are implemented in the modelling framework, and associated model simulations are compared with experimental data on coronary pressures and flows under a range of experimental conditions designed to interrogate the governing control mechanisms. Analysis identifies a maximally probable metabolic mechanism among the seven tested models, in which production of a metabolic signalling factor is proportional to myocardial oxygen consumption and delivery is proportional to flow. Finally, the identified model is validated based on comparisons of simulations with data on the myocardial perfusion response to conscious exercise that were not used for model identification. KEY POINTS: Although several competing hypotheses exist, we lack knowledge of specific nature of the metabolic mechanism(s) governing regional myocardial perfusion. Moreover, we lack an understanding of how parallel myogenic, adrenergic/autonomic and metabolic mechanisms work together to regulatory oxygen delivery in the beating heart. We have developed a multiscale modelling framework to test competing hypotheses against experimental data on coronary pressure, flow and myocardial oxygen delivery in the porcine heart in vivo. The analysis identifies a maximally probable metabolic mechanism among seven tested models, in which the production of a metabolic signalling factor is proportional to myocardial oxygen consumption and delivery is proportional to flow.

Myocardial Perfusion Imaging After Severe COVID-19 Infection Demonstrates Regional Ischemia Rather Than Global Blood Flow Reduction.

Background: Acute myocardial damage is common in severe COVID-19. Post-mortem studies have implicated microvascular thrombosis, with cardiovascular magnetic resonance (CMR) demonstrating a high prevalence of myocardial infarction and myocarditis-like scar. The microcirculatory sequelae are incompletely characterized. Perfusion CMR can quantify the stress myocardial blood flow (MBF) and identify its association with infarction and myocarditis.Objectives: To determine the impact of the severe hospitalized COVID-19 on global and regional myocardial perfusion in recovered patients.Methods: A case-control study of previously hospitalized, troponin-positive COVID-19 patients was undertaken. The results were compared with a propensity-matched, pre-COVID chest pain cohort (referred for clinical CMR; angiography subsequently demonstrating unobstructed coronary arteries) and 27 healthy volunteers (HV). The analysis used visual assessment for the regional perfusion defects and AI-based segmentation to derive the global and regional stress and rest MBF.Results: Ninety recovered post-COVID patients {median age 64 [interquartile range (IQR) 54–71] years, 83% male, 44% requiring the intensive care unit (ICU)} underwent adenosine-stress perfusion CMR at a median of 61 (IQR 29–146) days post-discharge. The mean left ventricular ejection fraction (LVEF) was 67 ± 10%; 10 (11%) with impaired LVEF. Fifty patients (56%) had late gadolinium enhancement (LGE); 15 (17%) had infarct-pattern, 31 (34%) had non-ischemic, and 4 (4.4%) had mixed pattern LGE. Thirty-two patients (36%) had adenosine-induced regional perfusion defects, 26 out of 32 with at least one segment without prior infarction. The global stress MBF in post-COVID patients was similar to the age-, sex- and co-morbidities of the matched controls (2.53 ± 0.77 vs. 2.52 ± 0.79 ml/g/min, p = 0.10), though lower than HV (3.00 ± 0.76 ml/g/min, p< 0.01).Conclusions: After severe hospitalized COVID-19 infection, patients who attended clinical ischemia testing had little evidence of significant microvascular disease at 2 months post-discharge. The high prevalence of regional inducible ischemia and/or infarction (nearly 40%) may suggest that occult coronary disease is an important putative mechanism for troponin elevation in this cohort. This should be considered hypothesis-generating for future studies which combine ischemia and anatomical assessment.

Relationship Between Myocardial Perfusion and Myocardial Function in Dilated Cardiomyopathy by Shown Ultrasonography.

Myocardial contrast echocardiography (MCE) and two-dimensional speckle tracking echocardiography (2D-STE) were used to detect left ventricular myocardial microcirculation perfusion and myocardial systolic function in dilated cardiomyopathy (DCM) and to explore the relationship between the two.Conventional ultrasound, MCE, and 2D-STE examinations were performed on 30 patients and 30 controls. Left ventricular microcirculation perfusion, left ventricular longitudinal strain (GLS), and circumferential strain (GCS) were analyzed to further compare the correlation between left ventricular perfusion and myocardial strain parameters.Regional myocardial perfusion was reduced in patients with DCM, manifesting as a decrease in the rising slope (A) of the mid-segment of the posterior septum, the peak intensity (PI) of the mid-segment of the anterior septum and the posterior septum, the apical segment of the lateral wall, the area under the curve (AUC) of the posterior septum, the basal segment of the posterior wall, the anterior septum, posterior septum, posterior wall, mid-segment of the lateral wall, and apical segment of the lateral wall and the overall average PI and AUC of the mid-segment, compared with that in the controls (P < 0.05). The left ventricular systolic function and the strain parameters GLS and GCS of DCM patients were lower than those of the controls (P < 0.001). Correlation analysis revealed a positive correlation between the A of the mitral valve and GCS (r = 0.372, P = 0.043), and MV-E/e' had a positive correlation with the AUC of the basal and intermediate segments (r = 0.379, P = 0.039; r = 0.404, P = 0.027).In patients with DCM, regional myocardial microcirculation perfusion is reduced, and myocardial strain is impaired. Myocardial perfusion has a good positive correlation with myocardial mechanics.

Exercise-Induced ST Changes in aVR, V5 and V1 in Differentiation between Single and Multi-Vessel Coronary Artery Disease

Background: Angina occurs when there is regional myocardial ischemia causedby inadequate coronary perfusion and is usually but not alwaysinduced by increases in myocardial oxygen requirements. Objective: The aim of this work was to study the significance of ST changes in aVR, V5, V1 during exercise ECG for diagnosis of single -or multi-vessel coronary artery disease. Patients and methods: This study had been carried out in the cardiology department, Zagazig University and National Hear Institute during the period from January 2005 to January 2007. This study included 56 patients (40 male +16 female) with chronic stable angina. Results: Comparison was done among groups regarding demographic data, resting ECG data, echocardiographic findings and there were no statistical significant difference among groups. Single vessel disease: LAD: - the ability of the test to detect left anterior descending (LAD) lesion as a single vessel disease has high specificity 87.5%, high +ve predictive value 96%, but low sensitivity 50%. Left circumflex (LCx): the sensitivity of the test to detect LCx lesion as a single vessel disease was 53.4%, specificity 60%, but with low +ve predictive value 44%. RCA: as regard RCA lesion the test has low sensitivity, specificity positive and negative predictive values. Conclusion: The concomitant appearance of exercise-induced ST-segment elevation in lead V1 and in lead aVR with simultaneous ST-segment depression in lead V5, or the isolated appearance of ST-segment elevation in lead V1 mostly detects single-vessel disease and correlates strongly with significant narrowing of the LAD coronary artery as single-vessel disease, or with significant stenosis of the LAD and LCx coronary arteries as double-vessel disease.

Prognostic Value of Single-Photon Emission Computed Tomography of Left Ventricular Synchronized with ECG for Cardiotoxicity Assessment in Patients with Malignant Lymphoma after High Dose Chemotherapy with Autologous Stem Cell Transplantation

Introduction: High-dose chemotherapy (HDC) with autologous hematopoietic stem cells transplantation (auto-HSCT) is currently widely used for the treatment of relapsed and refractory to standard chemotherapy cases of malignant lymphomas. Examination of patients for evaluation cardiotoxic effect of HDC and auto-HSCT is usually performed with an electrocardiography and echocardiography. The method of single photon emission computed tomography of the left ventricular(LV) myocardium, synchronized with the patient's ECG (Gated - SPECT) is rarely used to assess cardiotoxic effect of HDC and auto-HSCT, and its prognostic value in this field is not determined.Objective: to evaluate perfusion and regional myocardial function of the left ventricle (LV) using Gated-SPECT in malignant lymphomas patients receiving HDC and auto-HSCT. To evaluate whether the age and conditioning regimens influence the worsening of indices of hyperperfusion according to Gated-SPECT.Materials and methods: The study included 127 patients (67 with Hodgkin's lymphoma, 28 with non-Hodgkin's lymphoma, 32 with multiple myeloma). The median age was 37 year (range: 19 to 68 years); 80 females, 47 males. Gated-SPECT was used for assessment of perfusion and regional left ventricular function at rest before the HDC and auto-HSCT (point 1) and at discharge (point 2). The each study was performed on a double-headed rotating gamma camera «Forte» (Philips, USA) after intravenous injection of 740 MBq of technetium-99m-methoxyisobutylisonitrile (99mTc-MIBI). Gated-SPECT was used to measure the conventional parameters (total hypoperfusion defect, total LVEF) and also to measure regional myocardial perfusion and thickening used the 20-segment “bull's eye” model (the LV myocardium was divided into 20 segments).Results: The total area of hypoperfusion, expressed as a percentage of the area of the left ventricular myocardial wall did not change significantly during treatment (p> 0,05). However, segmental analysis of regional myocardial perfusion has revealed a statistically significant decrease in the median level uptake of the 99mTc-MIBI in 1,2,3,4,5,6,7,8,9,10,11,13,14,16,17,19,20 segments (p =0,01). The total ejection fraction (TEF) decreased, but change was not significant (median TEF at point 1 was 60,4 %, at point 2 - 59,9 %). But it showed a statistically significant decrease in median of local systolic thickening in 2,3,4,5,6,8,9,11,12,14,15,18,19,20 segments (p <0,05).It was also found that there was no correlation in the age of patients with hypoperfusion changes in the time of admission, but after treatment there was a direct significant weak correlation between these indices (R = 0.22, p = 0.01), So, older patient patient, have the greater size of the general hypoperfusion zone (Table 1).The analysis showed that the conditioning regimen (BEAM, high doses of melphalan or CBV) did not affect the index of the general hypoperfusion zone, which was established when comparing the parameters between pairs: ВЕАМ and high doses of melphalan, ВЕАМ and CBV, CBV and high doses of melphalan. Significant changes of general hypoperfusion zone were not detected when compare this indices at the time patients was admitted to the hospital with indices at the time of discharge from the hospital, that is, after HDC and auto-HSCTConclusions:HDC and auto-HSCT significantly change perfusion and regional LV myocardial function in patients with malignant lymphomas. Changes revealed evidence of diffuse myocardial damage. There was no difference in general hypoperfusion zone between different conditioning regimen before and after the treatment. Gated-SPECT can be considered as a promising method for assessing cardiac HDC and auto-HSCT. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Contradictory Effect of Coronary Collateral Circulation on Regional Myocardial Perfusion That Assessed by Quantitative Myocardial Perfusion Scintigraphy.

BackgroundPrevious studies showed conflicting results about the contribution of coronary collateral circulation (CCC) to myocardial perfusion and function. The aim of this study was to investigate these contradictory problems by gated myocardial perfusion scintigraphy (gated MPS) for the first time.MethodsThe current cohort was retrospectively selected among patients who underwent gated MPS and coronary angiography within 2 months. Two different groups including 96 patients were assessed by gated MPS to detect the understanding of the miscellaneous effect of CCC on myocardial perfusion. Group 1 consisted of those who had collateral arteries that were not-well-developed (Rentrop grade 0 - 1) (n = 58), while group 2 consisted of those who had collateral arteries that were well-developed (Rentrop grade 2 - 3) (n = 38).ResultsThere was no statistically significant difference between groups 1 and 2 in terms of perfusion and functional parameters obtained from gated MPS. Furthermore, no statistically significant difference was found in the phase analysis parameters which is a novel technique to evaluate left ventricular synchronization. On the other hand the left ventricular mass index values were high and quite close to the statistically significant value (P = 0.059) in group 2.ConclusionsThe current results that obtained by using the gated MPS technique for the first time in the evaluation of CCC showed that the well-developed collateral circulation has a positive effect on myocardial perfusion and function, but this effect was not statistically significant. Results need to be supported by large scale of patients’ size.