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This article reviews four new technologies for assessment of coronary hemodynamics based on medical imaging and artificial intelligence, including quantitative flow ratio (QFR), optical flow ratio (OFR), computational fractional flow reserve (CT-FFR) and artificial intelligence (AI)-based instantaneous wave-free ratio (iFR). These technologies use medical imaging such as coronary angiography, computed tomography angiography (CTA), and optical coherence tomography (OCT), to reconstruct three-dimensional vascular models through artificial intelligence algorithms, simulate and calculate hemodynamic parameters in the coronary arteries, and achieve noninvasive and rapid assessment of the functional significance of coronary stenosis. This article details the working principles, advantages such as non-invasiveness, efficiency, accuracy, limitations such as image dependency, and assumption restrictions, of each technology. It also compares and analyzes the image dependency, calculation accuracy, calculation speed, and operation simplicity, of the four technologies. The results show that these technologies are highly consistent with the traditional invasive wire method, and shows distinct advantages in terms of accuracy, reliability, convenience and cost-effectiveness, but there are also factors that affect accuracy. The results of this review demonstrates that AI-based iFR technology is currently one of the most promising technologies. The main challenges and directions for future development are also discussed. These technologies bring new ideas for the non-invasive assessment of coronary artery disease, and are expected to promote the technological progress in this field. [ABSTRACT FROM AUTHOR]

Physiologic assessment has become an essential tool to guide revascularization decisions due to the multiple limitations of angiographic and anatomic measures of physiologic significance. However, in certain cases the apparent physiologic measurement may not accurately reflect the severity of coronary disease compared with anatomical measurements. This article will review how anatomy trumps physiology in cases of acute coronary syndromes, left main disease, saphenous vein graft lesions, and myocardial bridging, and how to overcome the limitations of physiologic measurement in these clinical situations.

Purpose of reviewMultivessel coronary artery disease, defined as significant stenosis in two or more major coronary arteries, is associated with high morbidity and mortality. The diagnosis and treatment of multivessel disease have evolved in the PCI era from solely a visual estimation of ischemic risk to a functional evaluation during angiography. This review summarizes the evidence and discusses the commonly used methods of multivessel coronary artery stenosis physiologic assessment.Recent findingsWhile FFR remains the gold standard in coronary physiologic assessment, several pressure-wire-based non-hyperemic indices of functional stenosis have been developed and validated as well as wire-free angiographically derived quantitative flow ratio. Identifying and treating functionally significant coronary atherosclerotic lesions reduce symptoms and major adverse cardiovascular events. Coronary physiologic assessment in multivessel disease minimizes the observer bias in visual estimates of stenosis, changes clinical management, and improves patient outcomes.

Background Despite the proven benefits of transcatheter aortic valve replacement (TAVR) and its recent expansion toward the whole risk spectrum, coronary artery disease is present in more than half of the candidates for TAVR. Many previous studies do not focus on the longer‐term impact of TAVR on coronary arteries, and hemodynamic changes to the circulatory system in response to the anatomical changes caused by TAVR are not fully understood. Methods and Results We developed a multiscale patient‐specific computational framework to examine the effect of TAVR on coronary and cardiac hemodynamics noninvasively. Based on our findings, TAVR might have an adverse impact on coronary hemodynamics due to the lack of sufficient coronary blood flow during diastole phase (eg, maximum coronary flow rate reduced by 8.98%, 16.83%, and 22.73% in the left anterior descending, left circumflex coronary artery, and right coronary artery, respectively [N=31]). Moreover, TAVR may increase the left ventricle workload (eg, left ventricle workload increased by 2.52% [N=31]) and decrease the coronary wall shear stress (eg, maximum time averaged wall shear stress reduced by 9.47%, 7.75%, 6.94%, 8.07%, and 6.28% for bifurcation, left main coronary artery, left anterior descending, left circumflex coronary artery, and right coronary artery branches, respectively). Conclusions The transvalvular pressure gradient relief after TAVR might not result in coronary flow improvement and reduced cardiac load. Optimal revascularization strategy pre‐TAVR and progression of coronary artery disease after TAVR could be determined by noninvasive personalized computational modeling.

ObjectiveThe study aimed to investigate the diagnostic accuracy of Murray law–based quantitative flow ratio (μQFR) from a single angiographic view in patients with abnormal cardiac structure, left ventricular diastolic dysfunction, and valvular regurgitation.BackgroundμQFR is a novel fluid dynamics method for deriving fractional flow reserve (FFR). In addition, current studies of μQFR mainly analyzed patients with normal cardiac structure and function. The accuracy of μQFR when patients had abnormal cardiac structure, left ventricular diastolic dysfunction, and valvular regurgitation has not been clear.MethodsThis study retrospectively analyzed 261 patients with 286 vessels that underwent both FFR and μQFR prior to intervention. The cardiac structure and function were measured using echocardiography. Pressure wire–derived FFR ≤0.80 was defined as hemodynamically significant coronary stenosis.ResultsμQFR had a moderate correlation with FFR (r = 0.73, p

Objectives: The study aimed to evaluate the diagnostic performance of optical coherence tomography (OCT) in identifying functionally significant coronary stenosis in a vessel with single stenosis. Background: The OCT-based morphofunctional computational method for deriving the optical flow ratio (OFR) has diagnostic value, as it can identify the functional severity of coronary stenosis, but the ability of the OFR to aid the OCT in determining coronary stenosis hemodynamics in single-stenosis lesion remains unclear. Methods: 74 vessels with single stenosis were studied in 69 patients; all cases were performed through OCT and quantitative flow ratio (QFR), and OCT images were used to perform OFR. Results: Among vessels with single stenosis, OFR showed a good correlation with QFR (r = 0.86; p < 0.001). Taking QFR as the standard, the vessel-level diagnosis accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of OFR were 90% (95% CI: 81 to 96), 94% (95% CI: 77 to 99), 88% (95% CI: 74 to 96), 85% (95% CI: 68 to 94) and 95% (95% CI: 82 to 99), respectively. Among vessels with OFR/QFR concordance, both the minimum lumen area (MLA) and minimum lumen diameter (MLD) showed excellent diagnostic efficiency (MLA: area under the curve (AUC) = 0.92, 95% CI: 0.85 to 0.98, p < 0.001; MLD: AUC = 0.93, 95% CI: 0.86 to 0.98, p < 0.001) in determining the functional significance of coronary stenosis in a single stenosis lesion, and the best cutoff values were 1.55 mm2 and 1.40 mm. Conclusions: OFR has a good correlation with QFR. OCT-measured MLA and MLD have excellent diagnostic efficiency in identifying the hemodynamic significance of coronary stenosis in a vessel with single stenosis. [ABSTRACT FROM AUTHOR]

The mechanisms by which cardiac mechanics effect coronary perfusion (cardiac-to-coronary coupling) remain incompletely understood. Several coronary models have been proposed to deepen our understanding of coronary hemodynamics, but possibilities for in-depth studies on cardiac-to-coronary coupling are limited as mechanical properties like myocardial stress and strain are most often neglected. To overcome this limitation, a mathematical model of coronary mechanics and hemodynamics was implemented in the previously published multi-scale CircAdapt model of the closed-loop cardiovascular system. The coronary model consisted of a relatively simple one-dimensional network of the major conduit arteries and veins as well as a lumped parameter model with three transmural layers for the microcirculation. Intramyocardial pressure was assumed to arise from transmission of ventricular cavity pressure into the myocardial wall as well as myocardial stiffness, based on global pump mechanics and local myofiber mechanics. Model-predicted waveforms of global epicardial flow velocity, as well as of intramyocardial flow and diameter were qualitatively and quantitatively compared with reported data. Versatility of the model was demonstrated in a case study of aortic valve stenosis. The reference simulation correctly described the phasic pattern of coronary flow velocity, arterial flow impediment, and intramyocardial differences in coronary flow and diameter. Predicted retrograde flow during early systole in aortic valve stenosis was in agreement with measurements obtained in patients. In conclusion, we presented a powerful multi-scale modeling framework that enables realistic simulation of coronary mechanics and hemodynamics. This modeling framework can be used as a research platform for in-depth studies of cardiac-to-coronary coupling, enabling study of the effect of abnormal myocardial tissue properties on coronary hemodynamics. [ABSTRACT FROM AUTHOR]

Modelling of patient-specific hemodynamics for a clinical case of severe coronary artery disease with the bifurcation stenosis was carried out with allowance for standard angiographic data obtained before and after successfully performed myocardial revascularization by stenting of two arteries. Based on a non-Newtonian fluid model and an original algorithm for fluid dynamics computation operated with a limited amount of initial data, key characteristics of blood flow were determined to analyse the features of coronary disease and the consequences of its treatment. The results of hemodynamic modelling near bifurcation sites are presented with an emphasis on physical, physiological and clinical phenomena to demonstrate the feasibility of the proposed approach. The main limitations and ways to minimize them are the subjects of discussion as well. [ABSTRACT FROM AUTHOR]

The mechanisms by which cardiac mechanics effect coronary perfusion (cardiac-to-coronary coupling) remain incompletely understood. Several coronary models have been proposed to deepen our understanding of coronary hemodynamics, but possibilities for in-depth studies on cardiac-to-coronary coupling are limited as mechanical properties like myocardial stress and strain are most often neglected. To overcome this limitation, a mathematical model of coronary mechanics and hemodynamics was implemented in the previously published multi-scale CircAdapt model of the closed-loop cardiovascular system. The coronary model consisted of a relatively simple one-dimensional network of the major conduit arteries and veins as well as a lumped parameter model with three transmural layers for the microcirculation. Intramyocardial pressure was assumed to arise from transmission of ventricular cavity pressure into the myocardial wall as well as myocardial stiffness, based on global pump mechanics and local myofiber mechanics. Model-predicted waveforms of global epicardial flow velocity, as well as of intramyocardial flow and diameter were qualitatively and quantitatively compared with reported data. Versatility of the model was demonstrated in a case study of aortic valve stenosis. The reference simulation correctly described the phasic pattern of coronary flow velocity, arterial flow impediment, and intramyocardial differences in coronary flow and diameter. Predicted retrograde flow during early systole in aortic valve stenosis was in agreement with measurements obtained in patients. In conclusion, we presented a powerful multi-scale modeling framework that enables realistic simulation of coronary mechanics and hemodynamics. This modeling framework can be used as a research platform for in-depth studies of cardiac-to-coronary coupling, enabling study of the effect of abnormal myocardial tissue properties on coronary hemodynamics.

This article reviews four new technologies for assessment of coronary hemodynamics based on medical imaging and artificial intelligence, including quantitative flow ratio (QFR), optical flow ratio (OFR), computational fractional flow reserve (CT-FFR) and artificial intelligence (AI)-based instantaneous wave-free ratio (iFR). These technologies use medical imaging such as coronary angiography, computed tomography angiography (CTA), and optical coherence tomography (OCT), to reconstruct three-dimensional vascular models through artificial intelligence algorithms, simulate and calculate hemodynamic parameters in the coronary arteries, and achieve non-invasive and rapid assessment of the functional significance of coronary stenosis. This article details the working principles, advantages such as non-invasiveness, efficiency, accuracy, limitations such as image dependency, and assumption restrictions, of each technology. It also compares and analyzes the image dependency, calculation accuracy, calculation speed, and operation simplicity, of the four technologies. The results show that these technologies are highly consistent with the traditional invasive wire method, and shows distinct advantages in terms of accuracy, reliability, convenience and cost-effectiveness, but there are also factors that affect accuracy. The results of this review demonstrates that AI-based iFR technology is currently one of the most promising technologies. The main challenges and directions for future development are also discussed. These technologies bring new ideas for the non-invasive assessment of coronary artery disease, and are expected to promote the technological progress in this field., Competing Interests: The authors declare no conflict of interest., (Copyright: © 2024 The Author(s). Published by IMR Press.)

Physiologic assessment has become an essential tool to guide revascularization decisions due to the multiple limitations of angiographic and anatomic measures of physiologic significance. However, in certain cases the apparent physiologic measurement may not accurately reflect the severity of coronary disease compared with anatomical measurements. This article will review how anatomy trumps physiology in cases of acute coronary syndromes, left main disease, saphenous vein graft lesions, and myocardial bridging, and how to overcome the limitations of physiologic measurement in these clinical situations.

Abstract Objective Freshly isolated endothelial cells from both conduit arteries and microvasculature were used to test the hypothesis that eNOS protein content and nitric oxide production in coronary endothelial cells increases with vessel radius. Methods Porcine hearts were obtained from a local abattoir. Large and small arteries as well as arterioles were dissected free of myocardium and homogenized as whole vessels. Additionally, endothelial cells were isolated from both conduit arteries and left ventricular myocardium by tissue digestion with collagenase, followed by endothelial cell isolation using biotinylated-anti-CD31 and streptavidin-coated paramagnetic beads. Purity of isolated endothelial cells was confirmed by immunofluorescence and immunoblot. Results In whole vessel lysate, immunoblot analysis revealed that protein content for eNOS was greater in arterioles compared to small and large arteries. Nitric oxide metabolites (nitrite plus nitrate; NOx) levels measured from whole vessel lysate decreased as vessel size increased, with both arterioles and small arteries displaying significantly greater NOx content than conduit. Consistent with our hypothesis, both eNOS protein level and NOx were significantly greater in endothelial cells isolated from conduit arteries compared with those from coronary microvasculature. Furthermore, confocal microscopy revealed that eNOS protein was present in all conduit and microvascular endothelial cells, although eNOS staining was less intense in microvascular cells than those of conduit artery. Conclusions These findings demonstrate increased eNOS protein and NOx content in endothelial cells of conduit arteries compared with the microcirculation and underscore the importance of comparing endothelial-specific molecules in freshly isolated endothelial cells, rather than whole lysate of different sized vessels. Highlights • Greater eNOS protein levels in coronary endothelial cells of conduit vs. microvessel • Greater nitrite/nitrate in coronary endothelial cells of conduit vs. microvessel • eNOS protein present in all coronary conduit and microvascular endothelial cells • eNOS staining less intense in microvascular cells than those of conduit artery [ABSTRACT FROM AUTHOR]

Introduction: Both resting and hyperemic physiologic methods to guide coronary revascularization improve cardiovascular outcomes compared with angiographic guidance alone. Fractional flow reserve (FFR) remains underutilized due to concerns regarding hyperemia, prompting study of resting distal to aortic coronary pressure (Pd/Pa). Pd/Pa is a vasodilator-free resting index unlike FFR. While Pd/Pa is similar to another resting index, instantaneous wave-free ratio (iFR), it is a whole-cycle measurement not limited to the wave-free diastolic period. Pd/Pa is not validated clinically although multiple accuracy studies have been performed. Our meta-analysis examines the overall diagnostic accuracy of Pd/Pa referenced to FFR, the accepted invasive standard of ischemia.Methods: We searched PubMed, EMBASE, Central, ProQuest, and Web of Science databases for full text articles published through August 9, 2017 addressing the diagnostic accuracy of Pd/Pa referenced to FFR < 0.80. The following keywords were used: "distal coronary artery pressure" OR "Pd/Pa" AND "fractional flow reserve" OR "FFR."Results: In total, 14 studies comprising 7004 lesions were identified. Pooled diagnostic accuracy estimates of Pd/Pa versus FFR < 0.80 were: sensitivity, 0.77 (95% CI, 0.75-0.78); specificity, 0.82 (0.81-0.83); positive likelihood ratio, 4.7 (3.3-6.6); negative likelihood ratio, 0.29 (0.24-0.34); diagnostic odds ratio, 18.1 (14.4-22.6); area under the summary receiver-operating characteristic curve of 0.88; and diagnostic accuracy of 0.80 (0.76-0.83).Conclusions: Pd/Pa shows adequate agreement with FFR as a resting index of coronary stenosis severity without the undesired effects and cost of hyperemic agents. Pd/Pa has the potential to guide coronary revascularization with easier application and availability compared with iFR and FFR. [ABSTRACT FROM AUTHOR]

There is an ongoing debate on the extension of reperfusion-related microvascular damage (MVD) throughout the remote noninfarcted myocardial regions in patients with ST-elevation myocardial infarction (STEMI) that undergo primary percutaneous intervention (pPCI). The aim of this study was to elucidate the impact of reperfusion on remote microcirculatory territory by analyzing hemodynamic alterations in the nonculprit-vessel in relation to reperfusion. A total of 20 patients with STEMI undergoing pPCI were included. Peri-reperfusion temporal changes in hemodynamic parameters were obtained in angiographically normal nonculprit vessels before and 1-h after reopening of the culprit vessel. Intracoronary pressure and flow velocity data were compared using pairwise analyses (before and 1-h after reperfusion). In the non-culprit vessel, compared to the pre-reperfusion state, mean resting average peak velocity (33.4 ± 9.4 to 25.0 ± 4.9 cm/s, P < 0.001) and mean hyperemic average peak velocity (53.5 ± 14.4 to 42.1 ± 10.66 cm/s, P = 0.001) significantly decreased; whereas baseline (3.2 ± 1.0 to 4.0 ± 1.0 mmHg.cm−1.s, P < 0.001) and hyperemic microvascular resistance (HMR) (1.9 ± 0.6 to 2.4 ± 0.7 mmHg.cm−1.s, P < 0.001) and mean zero flow pressure (Pzf) values (32.5 ± 6.9 to 37.6 ± 8.3 mmHg, P = 0.003) significantly increased 1-h after reperfusion. In particular, the magnitude of changes in HMR and Pzf values following reperfusion were more prominent in patients with larger infarct size and with higher extent of MVD in the culprit vessel territory. Reperfusion-related microvascular injury extends to involve remote myocardial territory in relation to the magnitude of the adjacent infarction and infarct-zone MVD. (GUARD Clinical Trials NCT02732080). • Reperfusion induces microvascular injury in nonculprit vessel territory. • More severe nonculprit vessel microvascular injury accompanies larger infarct size. • Severity of microvascular damage in culprit and nonculprit vessels is associated. • Reperfusion induces significant perturbations in nonculprit vessel hemodynamics. [ABSTRACT FROM AUTHOR]

Background Despite the proven benefits of transcatheter aortic valve replacement (TAVR) and its recent expansion toward the whole risk spectrum, coronary artery disease is present in more than half of the candidates for TAVR. Many previous studies do not focus on the longer-term impact of TAVR on coronary arteries, and hemodynamic changes to the circulatory system in response to the anatomical changes caused by TAVR are not fully understood. Methods and Results We developed a multiscale patient-specific computational framework to examine the effect of TAVR on coronary and cardiac hemodynamics noninvasively. Based on our findings, TAVR might have an adverse impact on coronary hemodynamics due to the lack of sufficient coronary blood flow during diastole phase (eg, maximum coronary flow rate reduced by 8.98%, 16.83%, and 22.73% in the left anterior descending, left circumflex coronary artery, and right coronary artery, respectively [N=31]). Moreover, TAVR may increase the left ventricle workload (eg, left ventricle workload increased by 2.52% [N=31]) and decrease the coronary wall shear stress (eg, maximum time averaged wall shear stress reduced by 9.47%, 7.75%, 6.94%, 8.07%, and 6.28% for bifurcation, left main coronary artery, left anterior descending, left circumflex coronary artery, and right coronary artery branches, respectively). Conclusions The transvalvular pressure gradient relief after TAVR might not result in coronary flow improvement and reduced cardiac load. Optimal revascularization strategy pre-TAVR and progression of coronary artery disease after TAVR could be determined by noninvasive personalized computational modeling.

Objective: The study aimed to investigate the diagnostic accuracy of Murray law-based quantitative flow ratio (μQFR) from a single angiographic view in patients with abnormal cardiac structure, left ventricular diastolic dysfunction, and valvular regurgitation., Background: μQFR is a novel fluid dynamics method for deriving fractional flow reserve (FFR). In addition, current studies of μQFR mainly analyzed patients with normal cardiac structure and function. The accuracy of μQFR when patients had abnormal cardiac structure, left ventricular diastolic dysfunction, and valvular regurgitation has not been clear., Methods: This study retrospectively analyzed 261 patients with 286 vessels that underwent both FFR and μQFR prior to intervention. The cardiac structure and function were measured using echocardiography. Pressure wire-derived FFR ≤0.80 was defined as hemodynamically significant coronary stenosis., Results: μQFR had a moderate correlation with FFR ( r  = 0.73, p  < 0.001), and the Bland-Altman plot presented no difference between the μQFR and FFR (0.006 ± 0.075, p  = 0.192). With FFR as the standard, the diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of μQFR were 94.06% (90.65-96.50), 82.56% (72.87-89.90), 99.00% (96.44-99.88), 97.26 (89.91-99.30), and 92.96% (89.29-95.44), respectively. The concordance of μQFR/FFR was not associated with abnormal cardiac structure, valvular regurgitation (aortic valve, mitral valve, and tricuspid valve), and left ventricular diastolic function. Coronary hemodynamics showed no difference between normality and abnormality of cardiac structure and left ventricular diastolic function. Coronary hemodynamics demonstrated no difference among valvular regurgitation (none, mild, moderate, or severe)., Conclusion: μQFR showed an excellent agreement with FFR. The effect of abnormal cardiac structure, valvular regurgitation, and left ventricular diastolic function did not correlate with the diagnostic accuracy of μQFR. Coronary hemodynamics showed no difference in patients with abnormal cardiac structure, valvular regurgitation, and left ventricular diastolic function., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Yang, Huang, Li, Jia, Deng, Xie, Huang and Fei.)

Background: Despite the demonstrated benefits of transcatheter aortic valve replacement (TAVR), subclinical leaflet thrombosis and hypoattenuated leaflet thickening are commonly seen as initial indications of decreased valve durability and augmented risk of transient ischemic attack., Methods: We developed a multiscale patient-specific computational framework to quantify metrics of global circulatory function, metrics of global cardiac function, and local cardiac fluid dynamics of the aortic root and coronary arteries., Results: Based on our findings, TAVR might be associated with a high risk of blood stagnation in the neo-sinus region due to the lack of sufficient blood flow washout during the diastole phase (e.g., maximum blood stasis volume increased by 13, 8, and 2.7 fold in the left coronary cusp, right coronary cusp, and noncoronary cusp, respectively [N = 26]). Moreover, in some patients, TAVR might not be associated with left ventricle load relief (e.g., left ventricle load reduced only by 1.2 % [N = 26]) and diastolic coronary flow improvement (e.g., maximum coronary flow reduced by 4.94%, 15.05%, and 23.59% in the left anterior descending, left circumflex coronary artery, and right coronary artery, respectively, [N = 26])., Conclusions: The transvalvular pressure gradient amelioration after TAVR might not translate into adequate sinus blood washout, optimal coronary flow, and reduced cardiac stress. Noninvasive personalized computational modeling can facilitate the determination of the most effective revascularization strategy pre-TAVR and monitor leaflet thrombosis and coronary plaque progression post-TAVR., Competing Interests: The authors report no conflict of interest., (© 2023 The Authors.)

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The article discusses the development of instantaneous wave-free ratio (iFR) concept which serves as a standard of care for physiologic assessment of coronary lesions without inducing hyperemia. It mentions randomized trials involving iFR-guided percutaneous coronary intervention (PCI) to determine the causes nonfatal myocardial infarction and revascularization. It also states that hyperemia produces better separation of pressure and flow ensuring characterization of stenotic lesions.

The fractional flow reserve (FFR) is a widely used clinical index to evaluate the functional severity of coronary stenosis. A computer simulation method based on patients’ computed tomography (CT) data is a plausible non-invasive approach for computing the FFR. This method can provide a detailed solution for the stenosed coronary hemodynamics by coupling computational fluid dynamics (CFD) with the lumped parameter model (LPM) of the cardiovascular system. In this work, we have implemented a simple computational method to compute the FFR. As this method uses only coronary arteries for the CFD model and includes only the LPM of the coronary vascular system, it provides simpler boundary conditions for the coronary geometry and is computationally more efficient than existing approaches. To test the efficacy of this method, we simulated a three-dimensional straight vessel using CFD coupled with the LPM. The computed results were compared with those of the LPM. To validate this method in terms of clinically realistic geometry, a patient-specific model of stenosed coronary arteries was constructed from CT images, and the computed FFR was compared with clinically measured results. We evaluated the effect of a model aorta on the computed FFR and compared this with a model without the aorta. Computationally, the model without the aorta was more efficient than that with the aorta, reducing the CPU time required for computing a cardiac cycle to 43.4%. [ABSTRACT FROM AUTHOR]

The effects of angiotensin receptor blocker, diuretic, a calcium antagonist, and their combination were evaluated on the progression of cardiovascular and renal damage in spontaneously hypertensive rats (SHRs) given excess salt. To this end, 8-week male SHRs were divided into 7 groups. The control group (C) received normal NaCl (0.6%) diet. All other groups were given 8% NaCl rat chow. In addition, group 2 was given placebo (tap water alone), group 3 the angiotensin receptor antagonist telmisartan (10 mg/kg per d), group 4 received the diuretic chlorothiazide (80 mg/kg per d), group 5 was given telmisartan plus the diuretic, group 6 was given the calcium antagonist amlodipine (10 mg/kg per d), and group 7 was given telmisartan plus amlodipine. All treatments lasted for 8 weeks. Compared with controls, mean arterial pressure (MAP), renal blood flow, coronary flow reserve, minimal coronary vascular resistance, diastolic time constant, and maximal rate of ventricular pressure fall were all adversely affected by salt loading. Increased left ventricular mass with marked cardiac fibrosis was also found in the salt-overloaded SHR group. Telmisartan normalized all indices except MAP, whereas diuretic and amlodipine only partially restored cardiac functional and mass indexes. Combination therapy with telmisartan and either diuretic or amlodipine also normalized all indices including arterial pressure. These data suggest that (1) cardiovascular  damage induced by excess salt in the SHRs was not pressure dependent; (2) compared with the calcium antagonist and diuretic, blockade of angiotensin receptors  was extremely effective in this model. [ABSTRACT FROM PUBLISHER]

Abstract: Background: The abnormalities in coronary hemodynamics in systolic heart failure are frequent. Myocardial oxygen demand and consumption are increased and myocardial perfusion is also impaired, which may result in myocardial ischemia, necrosis, and apoptosis. This is potentially a contributing factor for progressive heart failure. Methods and Results: Neurohormonal abnormalities such as activated renin-angiotensin-aldosterone system, increased adrenergic activity, hemodynamic abnormalities such as decreased left ventricular perfusion pressure, and increased left ventricular diastolic pressure are important mechanisms for myocardial ischemia. Conclusions: Different pharmacologic agents may exert different effects on coronary hemodynamics although changes in systemic hemodynamics may be similar. Some agents may enhance myocardial ischemia and others may decrease it. Thus, an understanding of changes in coronary hemodynamics may have therapeutic implications. [Copyright &y& Elsevier]

A novel single-point technique to calculate local arterial wave speed (SPc) has recently been presented and applied in healthy human coronary arteries at baseline flow. We investigated its applicability for conditions commonly encountered in the catheterization laboratory. Intracoronary pressure (Pd) and Doppler velocity (U) were recorded in 29 patients at rest and during adenosine-induced hyperemia in a distal segment of a normal reference vessel and downstream of a single stenosis before and after revascularization. Conduit vessel tone was minimized with nitroglycerin. Microvascular resistance (MR) and SPc were calculated from Pd and U. In the reference vessel, SPc decreased from 21.5 mIs (SD 8.0) to 10.5 mIs (SD 4.1) after microvascular dilation (P < 0.0001). SPc was substantially higher in the presence of a proximal stenosis and decreased from 34.4 m/s (SD 18.2) at rest to 27.5 mIs (SD 13.4) during hyperemia (P < 0.0001), with a concomitant reduction in Pd by 20 mmHg and MR by 55.4%. The stent placement further reduced hyperemic MR by 26% and increased Pd by 26 mmHg but paradoxically decreased SPc to 13.1 m/s (SD 7.7) (P < 0.0001). Changes in SPc correlated strongly with changes in MR (P < 0.00 1) but were inversely related to changes in Pd (P < 0.01). In conclusion, the single-point method yielded erroneous predictions of changes in coronary wave speed induced by a proximal stenosis and distal vasodilation and is therefore not appropriate for estimating local wave speed in coronary vessels. Our findings are well described by a lumped reservoir model reflecting the "windkesselness" of the coronary arteries. [ABSTRACT FROM AUTHOR]

Objective: Although the effects of halogenated agents on both normal and diseased left ventricles have been widely studied, the influence of these anesthetic agents on right ventricular (RV) performance remains less well characterized. This study was undertaken to examine the effects of 2 different concentrations of sevoflurane on RV function, and coronary and pulmonary hemodynamics in acutely instrumented anesthetized pigs. Design: Prospective experimental study. Setting: Laboratory of experimental research in a university teaching hospital. Subjects: Anesthetized pigs. Interventions: Regional RV function in 10 pigs was determined from pressure segment length loop analysis, global RV function from stroke work versus end-diastolic pressure relation, right coronary blood flow, and pulmonary vascular resistance (PVR), without and then with 2.6% (minimum alveolar concentration [MAC]) and 3.9 % (1.5 MAC) end-tidal sevoflurane concentrations. Main Results: Sevoflurane preserved inflow systolic shortening and RV regional external work, but significantly depressed outflow systolic shortening (p < 0.05). Global RV stroke work was depressed to 72% ± 12% and 61% ± 10% of baseline value, respectively, with 1 and 1.5 MAC of sevoflurane (p < 0.05), but without alteration of PVR. Right coronary blood flow decreased dose dependently. Conclusions: Sevoflurane causes significant depression of global RV function associated with a qualitatively different effect on inflow and outflow tracts, without any modification of PVR. [Copyright &y& Elsevier]

Cites a study on the beneficial cardiovascular actions of eplerenone, an aldosterone antagonist, in the spontaneously hypertensive rat. Suggestion that aldosterone has been implicated as a potential mediator of cardiac and vascular damage in variety of disorders; Effect of eplerenone on cardiovascular mass, myocardial collagen and coronary circulation; Improvements in coronary and systemic hemodynamics in adult hypertensive rats during eplerenone administration.