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BACKGROUND: Glomerular hyperfiltration resulting from an elevated intraglomerular pressure (Pglom) is an important cause of CKD, but there is no feasible method to directly assess Pglom in humans. We developed a model to estimate Pglom in patients from combined renal arterial pressure and flow measurements. METHODS: We performed hemodynamic measurements in 34 patients undergoing renal or cardiac angiography under baseline conditions and during hyperemia induced by intrarenal dopamine infusion (30 μg/kg). For each participant during baseline and hyperemia, we fitted an adapted three-element Windkessel model that consisted of characteristic impedance, compliance, afferent resistance, and Pglom. RESULTS: We successfully analyzed data from 28 (82%) patients. Median age was 58 years (IQR, 52–65), median eGFR was 95 ml/min per 1.73 m(2) (IQR, 74–100) using the CKD-EPI formula, 30% had microalbuminuria, and 32% had diabetes. The model showed a mean Pglom of 48.0 mm Hg (SD=10.1) at baseline. Under hyperemia, flow increased by 88% (95% CI, 68% to 111%). This resulted in a 165% (95% CI, 79% to 294%) increase in afferent compliance and a 13.1-mm Hg (95% CI, 10.0 to 16.3) decrease in Pglom. In multiple linear regression analysis, diabetes (coefficient, 10.1; 95% CI, 5.1 to 15.1), BMI (0.99 per kg/m(2); 95% CI, 0.38 to 1.59), and renal perfusion pressure (0.42 per mm Hg; 95% CI, 0.25 to 0.59) were significantly positively associated with baseline Pglom. CONCLUSIONS: We constructed a model on the basis of proximal renal arterial pressure and flow velocity measurements that provides an overall estimate of glomerular pressure and afferent and efferent resistance in humans. The model provides a novel research technique to evaluate the hemodynamics of CKD on the basis of direct pressure and flow measurements. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: Functional HEmodynamics in patients with and without Renal Artery stenosis (HERA), NL40795.018.12 at the Dutch national trial registry (toetsingonline.nl).

Background: It remains uncertain if invasive coronary physiology beyond fractional flow reserve (FFR) can refine lesion selection for revascularization or provide additional prognostic value. Coronary flow reserve (CFR) equals the ratio of hyperemic to baseline flow velocity and has a wealth of invasive and noninvasive data supporting its validity. Because of fundamental physiologic relationships, binary classification of FFR and CFR disagrees in approximately 30%-40% of cases. Optimal management of these discordant cases requires further study. Aim: The aim of the study was to determine the prognostic value of combined FFR and CFR measurements to predict the 24-month rate of major adverse cardiac events. Secondary end points include repeatability of FFR and CFR, angina burden, and the percentage of successful FFR/CFR measurements which will not be excluded by the core laboratory. Methods: This prospective, nonblinded, nonrandomized, and multicenter study enrolled 455 subjects from 12 sites in Europe and Japan. Patients underwent physiologic lesion assessment using the 0.014” Philips Volcano ComboWire XT that provides simultaneous pressure and Doppler velocity sensors. Intermediate coronary lesions received only medical treatment unless both FFR (≤0.8) and CFR ( 0.80 and CFR ≥ 2.0. Enrollment has been completed, and final follow-up will occur in November 2019.

Background Microvascular dysfunction in the setting of ST-elevated myocardial infarction (STEMI) plays an important role in long-term poor clinical outcome. Coronary flow reserve (CFR) is a well-established physiological parameter to interrogate the coronary microcirculation. Together with hyperaemic average peak flow velocity, CFR constitutes the coronary flow capacity (CFC), a validated risk stratification tool in ischaemic heart disease with significant prognostic value. This mechanistic study aims to elucidate the time course of the microcirculation as reflected by alterations in microcirculatory physiological parameters in the acute phase and during follow-up in STEMI patients. Methods We assessed CFR and CFC in the culprit and non-culprit vessel in consecutive STEMI patients at baseline (n = 98) and after one-week (n = 64) and six-month follow-up (n = 65). Results A significant trend for culprit CFC in infarct size as determined by peak troponin T (p = 0.004), time to reperfusion (p = 0.038), the incidence of final Thrombolysis In Myocardial Infarction 3 flow (p = 0.019) and systolic retrograde flow (p = 0.043) was observed. Non-culprit CFC linear contrast analysis revealed a significant trend in C-reactive protein (p = 0.027), peak troponin T (p Conclusion This study demonstrates the importance of microcirculatory disturbances in the setting of STEMI, which is relevant for the interpretation of intracoronary diagnostic techniques which are influenced by both culprit and non-culprit vascular territories. Assessment of non-culprit vessel CFC in the setting of STEMI might improve risk stratification of these patients following coronary reperfusion of the culprit vessel.

Contains fulltext : 190517.pdf (Publisher’s version ) (Open Access) BACKGROUND: Coronary artery spasm may be the underlying mechanism in up to 10% of cases of acute coronary syndrome (ACS) and sudden cardiac death. Asian individuals exhibit a 3-times greater incidence of spasm than Caucasians; this is likely due to different types of mechanisms. Consequently, solid data is limited about the long-term prognosis in Caucasian patients presenting with ACS and/or out-of-hospital cardiac arrest (OHCA) caused by coronary spasm. METHODS: Between 2002 and 2015, thirty Caucasian patients with coronary artery spasm presenting with ACS (N = 29) and/or OHCA (N = 11) were enrolled in this prospective registry. Follow-up, consisting of regular outpatient visits, was conducted with a mean follow-up period of 7.5 +/- 3.3 years. Outcomes included presence of stable angina pectoris, recurrence of ACS, occurrence of implantable cardioverter defibrillator (ICD) shocks and death. RESULTS: The majority of patients (60%) remained asymptomatic during the entire follow-up period. At the end of the follow-up period only 3 patients still experienced stable angina (10%). Only 2 patients (7%) had a recurrent cardiac event, in which the ICD provided appropriate shock therapy. Half of the patients treated with stenting (N = 6), required re-interventions. CONCLUSION: Coronary spasm with ACS and/or OHCA in a Caucasian patient cohort has a relatively benign prognosis in the majority of patients in long-term follow-up, if treated appropriately with medical therapy. Both the role of ICD in OHCA secondary to coronary spasm, and the efficacy of stenting to treat vasospastic angina, warrant further study in large-sized prospective clinical trials.

Fractional flow reserve (FFR)-guided percutaneous coronary intervention results in better long-term clinical outcomes compared with coronary angiography alone in intermediate stenoses in stable coronary artery disease (CAD). Coronary physiology measurements have emerged for clinical decision making in interventional cardiology, but the focus lies mainly on epicardial vessels rather than the impact of these stenoses on the myocardial microcirculation. The latter can be quantified by measuring the coronary flow reserve (CFR), a combined pressure and flow index with a strong ability to predict clinical outcomes in CAD. However, combined pressure-flow measurements show 30–40 % discordance despite similar diagnostic accuracy between FFR and CFR, which is explained by the effect of microvascular resistance on both indices. Both epicardial and microcirculatory involvement has been acknowledged in ischaemic heart disease, but clinical implementation remains difficult as it requires individual proficiency. The recent introduced pressure-only index instantaneous wave-free ratio, a resting adenosine-free stenosis assessment, led to a revival of interest in coronary physiology measurements. This review focuses on elaborating the coronary physiological parameters and potential of combined pressure-flow measurements in daily clinical practice.

Purpose of Review: Accumulating evidence exists for the value of coronary physiology for clinical decision-making in ischemic heart disease (IHD). The most frequently used pressure-derived index to assess stenosis severity, the fractional flow reserve (FFR), has long been considered the gold standard for this purpose, despite the fact that the FFR assesses solely epicardial stenosis severity and aims to estimate coronary flow impairment in the coronary circulation. The coronary flow reserve (CFR) directly assesses coronary blood flow in the coronary circulation, including both the epicardial coronary artery and the coronary microvasculature, but is nowadays less established than FFR. It is now recognized that both tools may provide insight into the pathophysiological substrate of ischemic heart disease, and that particularly combined FFR and CFR measurements provide a comprehensive insight into the multilevel involvement of IHD. This review discusses the diagnostic and prognostic characteristics, as well as future implications of combined assessment of FFR and CFR pressure and flow measurements as parameters for inducible ischemia. Recent Findings: FFR and CFR disagree in up to 40% of all cases, giving rise to fundamental questions regarding the role of FFR in contemporary ischemic heart disease management, and implying a renewed approach in clinical management of these patients using combined coronary pressure and flow measurement to allow appropriate identification of patients at risk for cardiovascular events. Summary: This review emphasizes the value of comprehensive coronary physiology measurements in assessing the pathophysiological substrate of IHD, and the importance of acknowledging the broad spectrum of epicardial and microcirculatory involvement in IHD. Increasing interest and large clinical trials are expected to further strengthen the potential of advanced coronary physiology in interventional cardiology, consequently inducing reconsideration of current clinical guidelines.

An expansive collateral artery network is correlated with improved survival in case of adverse cardiac episodes. We aimed to identify cellular microRNAs (miRNA; miR) important for collateral artery growth. Chronic total occlusion (CTO) patients (n = 26) were dichotomized using pressure-derived collateral flow index (CFIp) measurements; high collateral capacity (CFIp > 0.39; n = 14) and low collateral (CFIp p values in stimulated monocytes. Ingenuity pathway analysis of predicted gene targets of miR339-5p and differential gene expression data from high versus low CFIp patients (n = 20), revealed significant association with STAT3 pathway, and also suggested a possible regulatory role for this signaling pathway. These results identify a novel association between miR339-5p and coronary collateral function. Future work examining modulation of miR339-5p and downstream effects on the STAT3 pathway and subsequent collateral vessel growth are warranted.

Background— The Navvus pressure sensor–equipped microcatheter allows to measure functional stenosis severity over a work-horse guidewire and is used as a more feasible alternative to regular sensor-equipped wires. However, Navvus is larger in diameter than contemporary sensor-equipped guidewires and may, thereby, influence functional measurements. The present study evaluates the hemodynamic influence of the Navvus microcatheter. Methods and Results— In patients with intermediate coronary stenosis, coronary pressure and flow velocity were measured using a dual sensor–equipped guidewire before and after introduction of Navvus. Patients were randomized to microcatheter-first or guidewire-first measurement. The primary end point was the difference in hyperemic stenosis resistance index between measurements before and after introduction of Navvus. Measurements were completed in 28 patients (28 stenoses). Mean hyperemic stenosis resistance was 0.37±0.19 Hg/cm/s for wire-only assessment and 0.48±0.26 Hg/cm/s after Navvus introduction ( P P =0.001). Passing–Bablok analysis revealed absence of a constant difference but significant proportional difference between the methods. Mean fractional flow reserve was 0.86±0.06 for wire-only assessment and 0.82±0.07 after Navvus introduction ( P P =0.036). Passing–Bablok analysis revealed significant constant and proportional differences between methods. Similar results were documented for resting indices of stenosis severity. Conclusions— Introduction of the Navvus microcatheter leads to clinically relevant stenosis severity overestimation in intermediate stenosis.