Coronary Hemodynamics Research Articles

Usefulness of Single Photon Emission Computed Tomography/Computed Tomography Fusion-Hybrid Imaging to Evaluate Coronary Artery Disorders in Patients with a History of Kawasaki Disease.

The coronary arterial lesions of Kawasaki disease are mainly dilative lesions, aneurysms, and stenotic lesions formed before, after, and between aneurysms; these lesions develop in multiple branches resulting in complex coronary hemodynamics. Diagnosis of myocardial ischemia and infarction and evaluation of the culprit coronary arteries and regions is critical to evaluating the treatment and prognosis of patients. This study used hybrid imaging, in which multidetector computed tomographic (CT) images for coronary CT angiography (CCTA) and stress myocardial perfusion single-photon emission CT (SPECT) images were fused. We investigated the diagnosis of blood vessels and regions responsible for myocardial ischemia and infarction in patients with complex coronary arterial lesions; in addition, we evaluated myocardial lesions that developed directly under giant coronary artery aneurysms. The subjects were 17 patients with Kawasaki disease with multiple coronary arterial lesions (median age, 18.0 years; 16 male). Both CCTA using 64-row CT and adenosine-loading myocardial SPECT were performed. Three branches, the right coronary artery (RCA), left anterior descending branch (LAD), and left circumflex branch, were evaluated with the conventional side-by-side interpretation, in which the images were lined up for diagnosis, and hybrid imaging, in which the CCTA and SPECT images were fused with computer processing. In addition, the myocardial lesions directly under giant coronary artery aneurysms were investigated with fusion imaging. Images sufficient for evaluation were acquired in all 17 patients. In the RCA, coronary arterial lesions were detected with CCTA in 16 patients. The evaluations were consistent between the side-by-side and fusion interpretation in 14 patients, and the blood vessel responsible for the myocardial ischemic region was identified in 2 patients. In the left circumflex branch, coronary arterial lesions were confirmed with 3-dimensional CT in 5 patients, and the the culprit coronary arteries for myocardial ischemia/infarction were confirmed with the fusion interpretation but not with the side-by-side interpretation. In the LAD, coronary arterial lesions were present in all patients, and the diagnosis was made with the fusion interpretation in 10 patients. In the LAD, small-range infarct lesions were detected directly under the giant coronary artery aneurysm in 8 patients, but were not confirmed with the side-by-side interpretation. Fusion imaging was capable of accurately evaluating myocardial ischemia/infarction as cardiovascular sequelae of Kawasaki disease and confirming the culprit coronary arteries. In addition, analysis of fusion images confirmed that small-range infarct lesions were concomitantly present directly under giant coronary artery aneurysms in the anterior descending coronary artery.

Abstract 19898: In-vitro Assessment of Coronary Hemodynamics in 3D Printed Patient-specific Geometry

Introduction: Recent advances in cardiac imaging permit detailed assessment of myocardial perfusion using Single Photon Emission Computed Tomography and integrated evaluation of coronary anatomy and myocardial perfusion using Computed Tomography [CT]. However, neither technique is adequate to evaluate coronary physiology on a per-vessel level, limiting diagnostic accuracy compared to invasive physiologic gold standards, e.g. fractional flow reserve (FFR). Recently, computational fluid dynamics (CFD) applied to CT imaging offers per-vessel hemodynamic analysis and has been shown to improve the diagnostic performance over CT alone compared to invasive FFR. In this study, we developed an alternative in-vitro method to quantify coronary hemodynamics in a 3D printed patient-specific geometry, replicating in-vivo physiologic conditions. Hypothesis: Our approach overcome inevitable numerical assumptions (rigid walls and unrealistic boundary conditions) made in CFD and can potentially lead to a more favorable diagnostic performance. Methods: In Figure 1, patient-specific replica was fabricated from segmented coronary arteries using high-resolution 3D printing. It was used to examine the hemodynamic variables (velocity, pressure and FFR) by a flow circulation system including a programmable flow pump, tunable flow impedances, pressure sensors, and particle image velocimetry. Results: Our initial experiments demonstrated the concordance of our in-vitro results to in in-vivo measurements. Instead of interrogating only one flow condition in CFD, our system allows for assessment of a given coronary lesion under a range of flow conditions from rest to maximal stress at no additional effort after initial setup. Conclusions: We expect our approach will provide a new competitive way to identify coronary lesion, and more importantly, the flow condition under which a given lesion becomes hemodynamically significant.

Development of an In Vitro Model to Characterize the Effects of Transcatheter Aortic Valve on Coronary Artery Flow.

Impairment of coronary artery flow, in either acute or chronic conditions, is a severe complication of transcatheter aortic valve (TAV) implantation, which can arise due to improper TAV positioning. However, little work has been done to quantify the effects of the TAV positioning on the coronary flow. In this study, a realistic in vitro model of coronary artery flow was developed and used to investigate the impact of TAV deployed orientations on coronary flow. The coronary hemodynamics was first replicated mathematically using a lumped parameter model with time-varying myocardial resistance. Based on the analytical model, two stepper motor controlled stopcock valves were integrated in a left heart simulator to represent the variable myocardial resistance in the experimental setup. The coronary flow and pressure waveforms obtained from the in vitro system were consistent with published data. With a TAV deployed in different orientations, the measured results demonstrated that TAV orientation does not have a significant impact on the coronary flow. The developed in vitro model can be further utilized to simulate coronary flow under various pathological conditions.

Effects of Vessel Tortuosity on Coronary Hemodynamics: An Idealized and Patient-Specific Computational Study.

Although coronary tortuosity can influence the hemodynamics of coronary arteries, the relationship between tortuosity and flow has not been thoroughly investigated partly due to the absence of a widely accepted definition of tortuosity and the lack of patient-specific studies that analyze complete coronary trees. Using a computational approach we investigated the effects of tortuosity on coronary flow parameters including pressure drop, wall shear stress, and helical flow strength as measured by helicity intensity. Our analysis considered idealized and patient-specific geometries. Overall results indicate that perfusion pressure decreases with increased tortuosity, but the patient-specific results show that more tortuous vessels have higher physiological wall shear stress values. Differences between the idealized and patient-specific results reveal that an accurate representation of coronary tortuosity must account for all relevant geometric aspects, including curvature imposed by the heart shape. The patient-specific results exhibit a strong correlation between tortuosity and helicity intensity, and the corresponding helical flow contributes directly to the observed increase in wall shear stress. Therefore, helicity intensity may prove helpful in developing a universal parameter to describe tortuosity and assess its impact on patient health. Our data suggest that increased tortuosity could have a deleterious impact via a reduction in coronary perfusion pressure, but the attendant increase in wall shear stress could afford protection against atherosclerosis.

Left ventricular diastolic dysfunction in Nrf2 knock out mice is associated with cardiac hypertrophy, decreased expression of SERCA2a, and preserved endothelial function

Increased production of reactive oxygen species and failure of the antioxidant defense system are considered to play a central role in the pathogenesis of cardiovascular disease. The transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is a key master switch controlling the expression of antioxidant and protective enzymes, and was proposed to participate in protection of vascular and cardiac function. This study was undertaken to analyze cardiac and vascular phenotype of mice lacking Nrf2. We found that Nrf2 knock out (Nrf2 KO) mice have a left ventricular (LV) diastolic dysfunction, characterized by prolonged E wave deceleration time, relaxation time and total diastolic time, increased E/A ratio and myocardial performance index, as assessed by echocardiography. LV dysfunction in Nrf2 KO mice was associated with cardiac hypertrophy, and a downregulation of the sarcoplasmic reticulum Ca2+-ATPase (SERCA2a) in the myocardium. Accordingly, cardiac relaxation was impaired, as demonstrated by decreased responses to β-adrenergic stimulation by isoproterenol ex vivo, and to the cardiac glycoside ouabain in vivo. Surprisingly, we found that vascular endothelial function and endothelial nitric oxide synthase (eNOS)-mediated vascular responses were fully preserved, blood pressure was decreased, and eNOS was upregulated in the aorta and the heart of Nrf2 KO mice. Taken together, these results show that LV dysfunction in Nrf2 KO mice is mainly associated with cardiac hypertrophy and downregulation of SERCA2a, and is independent from changes in coronary vascular function or systemic hemodynamics, which are preserved by a compensatory upregulation of eNOS. These data provide new insights into how Nrf2 expression/function impacts the cardiovascular system.

The NO-cGMP pathway participates in vascular adaptation to oxidative stress in Nrf2 KO mice

Background Endothelial dysfunction is considered both as cause and consequence of oxidative stress. Mice lacking the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2 KO) can be considered as a model of chronic adaption of the organism to oxidative stress, as they miss a key master switch controlling the expression of antioxidant and protective enzymes involved in the regulation of the cellular redox state. In this study we aimed to investigate the coronary and vascular phenotype and systemic hemodynamics of these mice compared to wild type (WT) littermates.

The Effects That Cardiac Motion has on Coronary Hemodynamics and Catheter Trackability Forces for the Treatment of Coronary Artery Disease: An In Vitro Assessment.

The coronary arterial tree experiences large displacements due to the contraction and expansion of the cardiac muscle and may influence coronary haemodynamics and stent placement. The accurate measurement of catheter trackability forces within physiological relevant test systems is required for optimum catheter design. The effects of cardiac motion on coronary flowrates, pressure drops, and stent delivery has not been previously experimentally assessed. A cardiac simulator was designed and manufactured which replicates physiological coronary flowrates and cardiac motion within a patient-specific geometry. A motorized delivery system delivered a commercially available coronary stent system and monitored the trackability forces along three phantom patient-specific thin walled compliant coronary vessels supported by a dynamic cardiac phantom model. Pressure drop variation is more sensitive to cardiac motion than outlet flowrates. Maximum pressure drops varied from 7 to 49 mmHg for a stenosis % area reduction of 56 to 90%. There was a strong positive linear correlation of cumulative trackability force with the cumulative curvature. The maximum trackability forces and curvature ranged from 0.24 to 0.87 N and 0.06 to 0.22 mm(-1) respectively for all three vessels. There were maximum and average percentage differences in trackability forces of (23-49%) and (1.9-5.2%) respectively when comparing a static pressure case with the inclusion of pulsatile flow and cardiac motion. Cardiac motion with pulsatile flow significantly altered (p value <0.001) the trackability forces along the delivery pathways with high local percentage variations and pressure drop measurements.

Impact of Aortic Valve Stenosis on Coronary Hemodynamics and the Instantaneous Effect of Transcatheter Aortic Valve Implantation.

Aortic valve stenosis (AS) induces compensatory alterations in left ventricular hemodynamics, leading to physiological and pathological alterations in coronary hemodynamics. Relief of AS by transcatheter aortic valve implantation (TAVI) decreases ventricular afterload and is expected to improve microvascular function immediately. We evaluated the effect of AS on coronary hemodynamics and the immediate effect of TAVI. Intracoronary pressure and flow velocity were simultaneously assessed at rest and at maximal hyperemia in an unobstructed coronary artery in 27 patients with AS before and immediately after TAVI and in 28 patients without AS. Baseline flow velocity was higher and baseline microvascular resistance was lower in patients with AS as compared with controls, which remained unaltered post-TAVI. In patients with AS, hyperemic flow velocity was significantly lower as compared with controls (44.5±14.5 versus 54.3±18.6 cm/s; P=0.04). Hyperemic microvascular resistance (expressed in mm Hg·cm·s(-1)) was 2.10±0.69 in patients with AS as compared with 1.80±0.60 in controls (P=0.096). Coronary flow velocity reserve in patients with AS was lower, 1.9±0.5 versus 2.7±0.7 in controls (P<0.001). Improvement in coronary hemodynamics after TAVI was most pronounced in patients without post-TAVI aortic regurgitation. In these patients (n=20), hyperemic flow velocity increased significantly from 46.24±15.47 pre-TAVI to 56.56±17.44 cm/s post-TAVI (P=0.003). Hyperemic microvascular resistance decreased from 2.03±0.71 to 1.66±0.45 (P=0.050). Coronary flow velocity reserve increased significantly from 1.9±0.4 to 2.2±0.6 (P=0.009). The vasodilatory reserve capacity of the coronary circulation is reduced in AS. TAVI induces an immediate decrease in hyperemic microvascular resistance and a concomitant increase in hyperemic flow velocity, resulting in immediate improvement in coronary vasodilatory reserve.

Computational analysis of stenosis geometry effects on right coronary hemodynamics.

Coronary artery disease (CAD) is one of the most frequent causes of death in western countries. It is characterized by the presence of coronary artery stenosis that can be flow-limiting or susceptible to rupture, triggering intracoronary thrombosis and -consequently- an acute myocardial infarction. For these reasons, hemodynamic alterations associated to the presence of coronary stenosis are of large relevance. Aim of this study was to numerically investigate the effect of stenosis geometry on hemodynamics, comparing three different shapes with an equivalent stenotic lumen. A right coronary artery (RCA) was reconstructed from the angiogram of a patient. Flow pattern analyses were performed using the computational fluid dynamic (CFD) approach, showing that the worst stenosis geometry is the elliptical one, characterized by areas with stasis, multidirectional velocity and high wall shear stress (WSS). On the other hand, the least dangerous stenosis is the parabolic one. However, the strongest predictor of pressure drop is not geometry but the minimal lumen area. In conclusion, while the minimal lumen area is associated to the trans-stenotic pressure drop, stenosis geometry has a significant impact on translesional flow pattern and WSS.

Repeatability of Fractional Flow Reserve Despite Variations in Systemic and Coronary Hemodynamics.

This study classified and quantified the variation in fractional flow reserve (FFR) due to fluctuations in systemic and coronary hemodynamics during intravenous adenosine infusion. Although FFR has become a key invasive tool to guide treatment, questions remain regarding its repeatability and stability during intravenous adenosine infusion because of systemic effects that can alter driving pressure and heart rate. We reanalyzed data from the VERIFY (VERification of Instantaneous Wave-Free Ratio and Fractional Flow Reserve for the Assessment of Coronary Artery Stenosis Severity in EverydaY Practice) study, which enrolled consecutive patients who were infused with intravenous adenosine at 140 μg/kg/min and measured FFR twice. Raw phasic pressure tracings from the aorta (Pa) and distal coronary artery (Pd) were transformed into moving averages of Pd/Pa. Visual analysis grouped Pd/Pa curves into patterns of similar response. Quantitative analysis of the Pd/Pa curves identified the "smart minimum" FFR using a novel algorithm, which was compared with human core laboratory analysis. A total of 190 complete pairs came from 206 patients after exclusions. Visual analysis revealed 3 Pd/Pa patterns: "classic" (sigmoid) in 57%, "humped" (sigmoid with superimposed bumps of varying height) in 39%, and "unusual" (no pattern) in 4%. The Pd/Pa pattern repeated itself in 67% of patient pairs. Despite variability of Pd/Pa during the hyperemic period, the "smart minimum" FFR demonstrated excellent repeatability (bias -0.001, SD 0.018, paired p = 0.93, r(2) = 98.2%, coefficient of variation = 2.5%). Our algorithm produced FFR values not significantly different from human core laboratory analysis (paired p = 0.43 vs. VERIFY; p = 0.34 vs. RESOLVE). Intravenous adenosine produced 3 general patterns of Pd/Pa response, with associated variability in aortic and coronary pressure and heart rate during the hyperemic period. Nevertheless, FFR - when chosen appropriately - proved to be a highly reproducible value. Therefore, operators can confidently select the "smart minimum" FFR for patient care. Our results suggest that this selection process can be automated, yet comparable to human core laboratory analysis.

The influence of basic anti-ischemic therapy on coronary haemodynamics in patients with stable coronary arteries desease

The influence of basic anti-ischemic therapy on coronary haemodynamics in patients with stable coronary arteries desease

Abstract 152: Tri-Dimentional Fusion Image of Multidetector 64-Slice-Computed Tomography and Single-Photon Emission Computed Tomography enables us to Evaluate Complicated Hemodynamics in Patients with Coronary Artery Lesions after Kawasaki Disease

Introduction: An important complication of Kawasaki disease (KD) is myocardial ischemia and acute myocardial infarction which occurs by thrombosis in coronary aneurysms and severe stenosis. The most characteristic features of coronary artery lesions (CALs) are dilation or aneurysm in acute stage and stenosis after convalescence stage. As these lesions exist singly or multiply in one coronary branch or multiple branches, coronary hemodynamics can be complicated. Ordinal methods have less potential for detection of these diseased states. Recently, Fusion imaging from coronary CT angiography (CTA) /SPECT has been thought good method for evaluation of location and severity of myocardial damages in adults. Therefore, we evaluate CALs, ischemia, and infarction after KD by Fusion imaging. Patients and Method: Seventeen patients (16 males and 1 female, age10 to 34 y) were subject. Eight patients had coronary artery bypass grafting (CABG). These tests were performed 8 to 30 years after onset of KD. CTA are performed by 64-slice-CT (LightSpeed VCT:GE Healthcare) ,and SPECT (Infinia:GE) by Tc-tetrofosmin was performed at rest and at stress after infusing adenosine. CTA and SPECT images were fused by the software (CardIQ Fusion:GE). Results and findings: In all cases, we had enough good images to detect the location of CALs and the area of ischemia. 1) Fusion images showed that no patient had significant stenotic findings at the anastomosis of bypass-graft at least several years after CABG. 2) Coronary native small branches arose from giant aneurysm were occluded by thrombosis and sub-aneurysmal lesions were infracted which were not detected by ordinal method. 3) Minimum sized myocardial ischemic lesions along to the normal visual epicardial coronary artery were detected and were suspected the existence of abnormal micro-coronary circulation caused by fibrous plaque or micro-thrombosis. 4) Collateral arteries at the stenotic and/or occluded lesions with or without ischemia were clearly detected by Fusion method. conclusion: Fusion images can visualize morphologically and functionally complicated CALs, myocardial ischemia ,and myocardial infarction after KD. Also, we can realize that peripheral coronary vessels are damaged with myocardial ischemia.

Functional heart condition during anesthesia on the basis of sevoflurane and propofol in patients of elderly and senile age

The hemodynamic parameters using balanced anesthesia based on propofol and sevoflurane in elderly patients are studied. The aim of the present work was to study the parameters of systemic hemodynamics in anesthesiology maintenance of operations coronary artery bypass graft in elderly and senile patients.Methods. A total of 36 patients from 65 to 83 years who underwent myocardial revascularization using sevoflurane and propofol are examined. The indicators that reflect the functional state of the heart, coronary blood flow and systemic hemodynamics in general are registered.Results. For combining use of sevoflurane and propofol it is observed a decrease of stroke work index of left ventricular, stroke index, ejection fraction, which was accompanied by decrease in the degree of shortening of the anteroposterior size of the left ventricle during systole and a decrease in the index of general peripheral resistance. Coronary perfusion index also tended to decrease.Conclusion. Using a combination of sevoflurane and propofol during coronary artery bypass graft in elderly and senile patients it is recorded a decrease of contractile ability of the myocardium and coronary blood flow depletion, which was connected with vasodilatation and decrease of coronary perfusion

Variability in IV Adenosine‐Induced Coronary Microvascular Resistance and Systemic Pressure Compromises FFR Determination despite Stable Stenosis Hemodynamics

AimTo investigate the effect of intracoronary (IC) and intravenous (IV) adenosine administration on variability in coronary and stenosis hemodynamics.MethodsIn 12 diseased coronary vessels (25‐56% DS), aortic pressure (Pa), distal pressure (Pd) and flow velocity (v) were simultaneously measured at baseline and hyperemia induced by IC (40 μg bolus) and IV adenosine administration (140 μg/kg/min). At baseline and throughout the hyperemic response we obtained cycle‐averaged pressure and velocity signals to derive microvascular resistance (MR = Pd/v) and FFR= Pd/Pa. From fitted stenosis pressure gradient‐velocity (ΔP‐v) relations, we determined ΔP at v= 30 cm/s (dPv30).ResultsMaximal v was similar for IC and IV adenosine (50 ± 4 vs. 54 ± 5 cm/s) with no difference in MR (1.73 ± 0.10 vs. 1.74 ± 0.13 mmHg/cm/s). However, MR during IV hyperemia rose between 9 and 135% in the post‐peak period, with concomitant fluctuations in v (13 to 61% decline) and pressures (up to 34% decline). Minimal FFR coincided with peak v for IC adenosine, but occurred 21 ± 8 s after peak v for IV adenosine, when Pa had decreased by 13% and HR increased by 25% vs. baseline. IV and IC derived stenosis ΔP‐v relations followed a stable common quadratic relationship, with no difference in dPv30.ConclusionIV adenosine caused persistent systemic and coronary hemodynamic variability. IC adenosine yielded comparable hyperemia with minor effects on systemic hemodynamics. Consistent ΔP‐v relations and dPv30 provide reliable means for stenosis evaluation free from maximal vasodilation.

Design and rationale for the randomised, double-blinded, placebo-controlled Liraglutide to Improve corONary haemodynamics during Exercise streSS (LIONESS) crossover study.

BackgroundGlucagon-like peptide-1 is an incretin hormone essential for normal human glucose homeostasis. Expression of the glucagon-like peptide-1 receptor in the myocardium has fuelled growing interest in the direct and indirect cardiovascular effects of native glucagon-like peptide-1, its degradation product glucagon-like peptide-1(9-36), and the synthetic glucagon-like peptide-1 receptor agonists. Preclinical studies have demonstrated cardioprotective actions of all three compounds in the setting of experimental myocardial infarction and left ventricular systolic dysfunction. This has led to Phase 2 trials of native glucagon-like peptide-1 and incretin-based therapies in humans with and without Type 2 diabetes mellitus. These studies have demonstrated the ability of glucagon-like peptide-1, independent of glycaemic control, to positively modulate the metabolic and haemodynamic parameters of individuals with coronary artery disease and left ventricular systolic dysfunction. We aim to add to this growing body of evidence by studying the effect of chronic glucagon-like peptide-1 receptor activation on exercise-induced ischaemia in patients with chronic stable angina managed conservatively or awaiting revascularisation. The hypothesis being liraglutide, a subcutaneously injectable glucagon-like peptide-1 receptor agonist, is able to improve exercise haemodynamics in patients with obstructive coronary artery disease when compared with saline placebo.Methods and designThe Liraglutide to Improve corONary haemodynamics during Exercise streSS (LIONESS) trial is an investigator-initiated single-centre randomised double-blinded placebo-controlled crossover proof-of-principle physiological study. Primary endpoints are change in rate pressure product at 0.1 mV ST-segment depression and change in degree of ST-segment depression at peak exercise during sequential exercise tolerance testing performed over a 6-week study period in which 26 patients will be randomised to either liraglutide or saline with crossover to the opposing regimen at week 3.DiscussionThe study will be conducted in accordance with the principles of Good Clinical Practice and the Declaration of Helsinki. The local Research Ethics Committee and Medicines and Healthcare Products Regulatory Agency have approved the study.Trial registrationNational Institute of Health Research Clinical Research Network (NIHR CRN) Portfolio ID 11112 and ClinicalTrials.gov Identifier NCT02315001.

Validation of high temporal resolution spiral phase velocity mapping of coronary artery blood flow against Doppler flow wire

Background The temporal pattern of coronary artery flow velocity through the cardiac cycle provides important information about coronary haemodynamics. The ‘gold standard’ for coronary artery velocity assessment is the Doppler flow wire which is inserted directly into the coronary artery under X-ray fluoroscopic guidance, which is invasive, uses ionising radiation and has a small but significant risk of serious complication. In this study, we perform an in vivo comparison of coronary blood flow velocities measured with breath-hold high temporal resolution spiral phase velocity mapping and Doppler flow wire measurements. Methods Breath-hold proximal coronary artery velocity maps were acquired in 5 left anterior descending (LAD) and 3 right coronary arteries (RCAs) in patients who had undergone invasive Doppler flow wire assessment as part of a clinical assessment. Acquisition parameters were: pixel size 1.4 × 1.4 mm (reconstructed to 0.7 ×0 .7 mm) ×8m m, true temporal resolution 19 ms, 1-1 water excitation (WE), 17 cardiac cycle breath-hold, velocity sensitivity 30-50cm/s, retrospective ECG gating (reconstructed 50 phases). Extraction of MR coronary artery blood flow velocitytime curves was performed using a custom MATLAB program which tracked the motion of the vessel over the cardiac cycle and corrected for the through-plane motion of the vessel using a region of adjacent tracked myocardium (LAD) or a region of surrounding epicardial fat (RCA) from a separately acquired fat-excitation acquisition. For each vessel, the mean through-plane motioncorrected MR velocities at all timepoints were plotted against the equivalent flow wire velocities. If necessary, the profiles were first time-shifted to take into account small differences in data triggering between the two techniques. The correlation between the two profiles was assessed using simple linear regression analysis. Results Figures 1 and 2 show example LAD and RCA studies. On average, the MR measured velocities were 66% less than the Flowire velocities (SD 9%, range: 50% - 78%). The correlation between the MR and flow wire data, however, was high, with R 2 values ranging from 0.6 - 0.95 in the 8 vessels studied (mean R 2 = .80).

Abstracts of the 2015 SCMR/EuroCMR Joint Scientific Sessions, February 4-7, 2015, Nice, France.

Background While blood flow in the majority of arteries peaks in systole, the rhythmic squeezing of the coronary arteries and microcirculation as the heart beats results in left anterior descending artery (LAD) flow being diastolicpredominant while for the right coronary artery (RCA), there is approximately equal flow in systole and diastole. These temporal flow patterns can provide important information on disease state. The aim of this study is to assess the inter-breath hold reproducibility of parameters of coronary haemodynamics using a high temporal resolution spiral phase velocity mapping technique and to compare automatic and manual analyses.

Does conventional intra-aortic balloon pump trigger timing produce optimal hemodynamic effects in vivo?

The intra-aortic balloon pump (IABP) provides circulatory support through counterpulsation. The hemodynamic effects of the IABP may vary with assisting frequency and depend on IAB inflation/deflation timing. We aimed to assess in vivo the IABP benefits on coronary, aortic, and left ventricular hemodynamics at different assistance frequencies and trigger timings. Six healthy, anesthetized, open-chest sheep received IABP support at 5 timing modes (EC, LC, CC, CE, CL, corresponding to early/late/conventional/conventional/conventional inflation and conventional/conventional/conventional/early/late deflation, respectively) with frequency 1:3 and 1:1. Aortic (Q(ao)) and coronary (Q(cor)) flow, and aortic (P(ao)) and left ventricular (PLV) pressure were recorded simultaneously, with and without IABP support. Integrating systolic Q(ao) yielded stroke volume (SV). EC at 1:1 produced the lowest end-diastolic P(ao) (59.5 ± 7.8 mmHg [EC], 63.4 ± 11.1 mmHg [CC]), CC at 1:1 the lowest systolic PLV (69.1 ± 6.5 mmHg [CC], 76.4 ± 6.5 mmHg [control]), CC at 1:1 the highest SV (88.5 ± 34.4 ml [CC], 76.6 ± 31.9 ml [control]) and CC at 1:3 the highest diastolic Qcor (187.2 ± 25.0 ml/min [CC], 149.9 ± 16.6 ml/min [control]). Diastolic P(ao) augmentation was enhanced by both assistance frequencies alike, and optimal timings were EC for 1:3 (10.4 ± 2.8 mmHg [EC], 6.7 ± 3.8 mmHg [CC]) and CC for 1:1 (10.8 ± 6.7 mmHg [CC], -3.0 ± 3.8 mmHg [control]). In our experiments, neither a single frequency nor a single inflation/deflation timing, including conventional IAB timing, has shown superiority by uniformly benefiting all studied hemodynamic parameters. A choice of optimal frequency and IAB timing might need to be made based on individual patient hemodynamic needs rather than as a generalized protocol.

Acute effects of chewing tobacco on coronary microcirculation and hemodynamics in habitual tobacco chewers

Background: Long-term adverse cardiovascular effects of smokeless tobacco are well established, however, the effect of chewing tobacco on coronary microcirculation and hemodynamic have not been studied. We intended to analyze the acute effect of chewing tobacco on coronary microcirculation and hemodynamics in habitual tobacco chewers with stable coronary artery disease undergoing elective percutaneous coronary intervention (PCI). Materials and Methods: We prospectively enrolled seven habitual tobacco chewers with stable coronary artery disease with single vessel disease or double vessel disease satisfying the criteria for elective PCI. Patients were instructed to keep 1 g of crushed dried tobacco leaves in the mouth after a successful PCI. Lesion in last stented vessels was evaluated for fractional flow reserve (FFR), coronary flow reserve (CFR), and index of microcirculatory resistance (IMR) post-PCI, after 15 min and 30 min of tobacco chewing along with the measurement of serum cotinine levels. Results: Oral tobacco led to high levels of cotinine in the majority of patients. There was an insignificant rise in heart rate, systolic and diastolic blood pressure following tobacco consumption. Baseline CFR (median 1.6, range 1.1–5.5) was low in tobacco chewers after PCI even after optimum FFR (0.9 ± 0.05) in the majority of patients suggesting abnormal microvascular hemodynamics (high IMR in 3 patients, overall median 14.2, range 7–36.2). However, there was no significant change in the estimated CFR or IMR values following tobacco chewing. One patient had bradycardia and hypotension which may be related to vagal reaction or acute nicotine poisoning. Conclusion: Tobacco chewers have abnormal coronary microcirculation hemodynamics even following a successful PCI. However, the coronary micocirculation and hemodynamics do not change acutely following tobacco chewing despite high serum cotinine concentrations.

Effects of vessel dynamics and compliance on human right coronary artery hemodynamics with / without stenosis

Effects of vessel dynamics and compliance on human right coronary artery hemodynamics with / without stenosis