Coronary Artery Pressure Research Articles

Correlation and consistency between resting full-cycle ratio and fractional flow reserve in assessing coronary artery function in a Chinese real-world cohort with non-ST-segment elevation acute coronary syndrome: a retrospective observational study

ObjectiveThe study aimed to investigate the correlation and consistency between resting full-cycle ratio (RFR) and fractional flow reserve (FFR) in functional assessment of coronary arteries in a Chinese real-world cohort...

Diagnostic performance of pressure-bounded coronary flow reserve.

Fluid dynamics studies have proposed that coronary flow reserve can be calculated from coronary artery pressure instead of coronary blood flow. We sought to investigate the diagnostic performance of pressure-bounded coronary flow reserve (pb-CFR) compared with CFR measured by conventional thermodilution method (CFRthermo) in the clinical setting. Pressure guidewire was used to measure CFRthermo and fractional flow reserve (FFR) in left anterior descending coronary artery in 62 patients with stable coronary artery disease. Pb-CFR was calculated only with resting distal coronary artery pressure (Pd), resting aortic pressure (Pa) and FFR. Pb-CFR was moderately correlated with CFRthermo (r = 0.54, P < 0.001). Pb-CFR showed a poor agreement with CFRthermo, presenting large values of mean difference and root mean square deviation (1.5 ± 1.4). Pb-CFR < 2.0 predicted CFRthermo < 2.0 with an accuracy of 79%, sensitivity of 83%, specificity of 78%, positive predictive value of 48%, negative predictive value of 95%. The discordance presenting CFRthermo < 2.0 and pb-CFR ≥ 2.0 was associated with diffuse disease (P < 0.001). The discordance presenting CFRthermo ≥ 2 and pb-CFR < 2 was associated with a high FFR (P = 0.002). Pb-CFR showed moderate correlation and poor agreement with CFRthermo. Pb-CFR might be reliable in excluding epicardial coronary artery disease and microcirculatory disorders.

Scoring model based on cardiac CT and clinical factors to predict early good mitral valverepair in rheumatic mitral disease.

We aimed to evaluate the mitral valve calcification and mitral structure detected by cardiac computed tomography (cardiac CT) and establish a scoring model based on cardiac CT and clinical factors to predict early good mitral valve repair (EGMR) and guide surgical strategy in rheumatic mitral disease (RMD). This is a retrospective bi-center cohort study. Based on cardiac CT, mitral valve calcification and mitral structure in RMD were quantified and evaluated. The primary outcome was EGMR. A logical regression algorithm was applied to the scoring model. A total of 579 patients were enrolled in our study from January 1, 2019, to August 31, 2022. Of these, 443 had baseline cardiac CT scans of adequate quality. The calcification quality score, calcification and thinnest part of the anterior leaflet clean zone, and papillary muscle symmetry were the independent CT factors of EGMR. Coronary artery disease and pulmonary artery pressure were the independent clinical factors of EGMR. Based on the above six factors, a scoring model was established. Sensitivity = 95% and specificity = 95% were presented with a cutoff value of 0.85 and 0.30 respectively. The area under the receiver operating characteristic of external validation set was 0.84 (95% confidence interval [CI] 0.73-0.93). Mitral valve repair is recommended when the scoring model value > 0.85 and mitral valve replacement is prior when the scoring model value < 0.30. This model could assist in guiding surgical strategies for RMD. The model established in this study can serve as a reference indicator for surgical repair in rheumatic mitral valve disease. • Cardiac CT can reflect the mitral structure in detail, especially for valve calcification. • A model based on cardiac CT and clinical factors for predicting early good mitral valverepair was established. • The developed model can help cardiac surgeons formulate appropriate surgical strategies.

Patient-specific modeling of blood flow in the coronary arteries

Patient-specific models of blood flow in the coronary arteries have entered clinical practice worldwide to aid in the diagnosis and management of heart disease. This technology leverages modern AI-based image segmentation methods to extract the geometry of the coronary arteries from noninvasive computed tomography volumetric imaging, computational physiology methods to define boundary conditions and computational fluid dynamic techniques to compute coronary artery flow and pressure. The methods described herein have been used to compute the fractional flow reserve (FFR) in the coronary arteries, namely the ratio of pressure in a coronary artery to the reference aortic pressure under conditions of maximum hyperemia induced by the intravenous administration of a vasodilator to mimic increased coronary artery blood flow as occurs during physical activity. The fractional flow reserve derived from coronary computed tomography angiography (CCTA) using patient-specific models of coronary artery blood flow is referred to as FFRCT and has been validated against invasive measurements using pressure wires in several hundred patients and subsequently evaluated in clinical trials in several thousand patients. Patient-specific models of coronary artery blood flow can be used to predict outcomes of coronary artery revascularization procedures, to identify patients at risk of having a heart attack, and to model tissue perfusion of the microcirculation by coupling with emerging models of cardiac function. This paper provides a state-of-the-art review of computational methods for, and applications of, quantifying blood flow in patient-specific models of the coronary arteries.

Hyperuricemia and diabetes mellitus when occurred together have higher risks than alone on all-cause mortality and end-stage renal disease in patients with chronic kidney disease

IntroductionHyperuricemia and diabetes mellitus (DM) are associated with increased mortality risk in patients with chronic kidney disease (CKD). Here we aimed to evaluate the independent and joint risks of these two conditions on mortality and end stage kidney disease (ESKD) in CKD-patients.MethodsThis retrospective cohort study enrolled 4380 outpatients (with CKD stage 3–5) with mortality and ESKD linkage during a 7-year period (from 2007 to 2013). All-causes mortality and ESKD risks were analyzed by multivariable-adjusted Cox proportional hazards models (adjusted for age, sex, smoke, previous coronary arterial disease, blood pressure, and medications for hyperlipidemia, hyperuricemia and renin–angiotensin system inhibitors).ResultsOverall, 40.5% of participants had DM and 66.4% had hyperuricemia. In total, 356 deaths and 932 ESKD events occurred during the 7 years follow-up. With the multivariate analysis, increased risks for all-cause mortality were: hyperuricemia alone, HR = 1.48 (1–2.19); DM alone, and HR = 1.52 (1.02–2.46); DM and hyperuricemia together, HR = 2.12 (1.41–3.19). Similar risks for ESKD were: hyperuricemia alone, HR = 1.34 (1.03–1.73); DM alone, HR = 1.59 (1.15–2.2); DM and hyperuricemia together, HR = 2.46 (1.87–3.22).ConclusionsDM and hyperuricemia are strongly associated with higher all-cause mortality and ESKD risk in patients with CKD stage 3–5. Hyperuricemia is similar to DM in terms of risk for all-cause mortality and ESKD. DM and hyperuricemia when occurred together further increase both risks of all-cause mortality and ESKD.

Association of dipping pattern of blood pressure and atherosclerotic burden of coronary arteries in hypertensive patients.

Aim The aim of this study was to determine the association between the dipping pattern of BP and coronary artery disease in hypertensive patients.Material and methods A total of 356 hypertensive patients were included in the study. The results of ambulatory BP monitoring, echocardiography, and coronary computerised tomographic angiography were evaluated retrospectively. The patients were divided into two groups on the basis of their ambulatory BP monitoring: 1) patients with the dipping pattern of BP; 2) patients with the non-dipping pattern (NDP).Results Among the 356 patients, 145 were male (40.7 %). The smoking status was higher in patients with NDP (p=0.023). The statin usage in patients with the dipping pattern was higher in patients with NDP (p=0.027). There were no significant differences in the echocardiographic findings. 58.6 % of the patients without plaque formation had the dipping pattern of BP (p&lt;0.05), however 84.4 % of patients with &gt;50 % plaque formation had the NDP of BP (p&lt;0.001).Conclusion The NDP of BP might be related to the increased atherosclerotic process in coronary arteries, and pa-tients with NDP might have an increased atherosclerotic burden for coronary arteries when compared with patients with a dipping pattern.

Know the Code: Medications for Resuscitation in Neonates.

Resuscitations in the delivery room or the nursery cause significant stress for caregivers. Diligent preparation will improve the efficacy and safety of life-saving interventions and increase staff comfort. When establishment of an airway and delivery of positive pressure ventilation and chest compressions fail to result in return of spontaneous circulation, pharmacotherapeutic interventions should be considered. Epinephrine is first-line pharmacotherapy for severe bradycardia or cardiac arrest, increasing coronary arterial pressure and blood flow during chest compressions. Despite limited data regarding dosing and efficacy, the first dose of epinephrine may be delivered through the endotracheal tube during attainment of venous access (preferably a low-lying umbilical venous catheter in the delivery room). Intravenous dosing is preferred, and any facility caring for newborns must ensure optimized logistics including readily available dosing guidance and optimal flush volumes. After provision of epinephrine, additional medications may be considered, especially for resuscitations occurring outside of the immediate perinatal period, including normal saline, glucose, adenosine, atropine, and calcium. Clinicians must understand the indications, dosing, and monitoring parameters for these medications and ensure rapid availability for resuscitation. Every second truly counts in a neonatal resuscitation, and optimal understanding and preparation will ensure delivery of pharmacotherapy to optimize both patient outcomes and staff comfort.

Fractional flow reserve-guided treatment in coronary artery disease: Clinical practice.

The assessment of functional severity of moderate coronary stenoses is challenging. Coronary angiography remains the standard technique for diagnosis, although, due to its limitations, it is frequently insufficient to detect relevant myocardial ischemia. Fractional flow reserve (FFR) is defined as the ratio between the mean hyperemic coronary artery pressure distal to the lesion and mean pressure in the aorta. The FFR measurement is currently supported by guidelines to evaluate the hemodynamic significance of lesions. Proper identification of patients that have the potential to benefit from revascularization is crucial. Based on already published literature, we focus on the long-term follow-up of patients with FFR-driven treatment. We also provide a review of specific clinical cases such as borderline FFR values, comorbidities or lesions in anatomical risk locations, in which interpretation can be challenging during the physiological assessment. The aim of this paper is to provide an overview of the evidence of FFR implementation in daily clinical practice and determine issues that raise doubts.

Randomized blinded trial of automated REBOA during CPR in a porcine model of cardiac arrest

BackgroundResuscitative endovascular balloon occlusion of the aorta (REBOA) reportedly elevates arterial blood pressure (ABP) during non-traumatic cardiac arrest. ObjectivesThis randomized, blinded trial of cardiac arrest in pigs evaluated the effect of automated REBOA two minutes after balloon inflation on ABP (primary endpoint) as well as arterial blood gas values and markers of cerebral haemodynamics and metabolism. MethodsTwenty anesthetized pigs were randomized to REBOA inflation or sham-inflation (n = 10 in each group) followed by insertion of invasive monitoring and a novel, automated REBOA catheter (NEURESCUE® Catheter & NEURESCUE® Assistant). Cardiac arrest was induced by ventricular pacing. Cardiopulmonary resuscitation was initiated three min after cardiac arrest, and the automated REBOA was inflated or sham-inflated (blinded to the investigators) five min after cardiac arrest. ResultsIn the inflation compared to the sham group, mean ABP above the REBOA balloon after inflation was higher (inflation: 54 (95%CI: 43–65) mmHg; sham: 44 (33–55) mmHg; P = 0.06), and diastolic ABP was higher (inflation: 38 (29–47) mmHg; sham: 26 (20–33) mmHg; P = 0.02), and the arterial to jugular oxygen content difference was lower (P = 0.04). After return of spontaneous circulation, mean ABP (inflation: 111 (95%CI: 94–128) mmHg; sham: 94 (95%CI: 65–123) mmHg; P = 0.04), diastolic ABP (inflation: 95 (95%CI: 78−113) mmHg; sham: 78 (95%CI: 50−105) mmHg; P = 0.02), CPP (P = 0.01), and brain tissue oxygen tension (inflation: 315 (95%CI: 139−491)% of baseline; sham: 204 (95%CI: 75−333)%; P = 0.04) were higher in the inflation compared to the sham group. ConclusionInflation of REBOA in a porcine model of non-traumatic cardiac arrest improves central diastolic arterial pressure as a surrogate marker of coronary artery pressure, and cerebral perfusion. Institutional protocol number2017-15-0201-01371.

Functional assessment of intermediate coronary artery stenosis with 4-Fr catheters.

The 4-Fr catheter system is not recommended for invasive functional assessment of coronary artery stenosis, because it tends to distort the aortic waveform. This study aimed to identify the incidence of aortic waveform distortion and a feasible method for correct diagnosis of coronary artery stenosis with a 4-Fr catheter. We retrospectively investigated 178 lesions with intermediate coronary artery stenosis. Non-hyperemic distal coronary artery pressure (Pd) and aortic pressure (Pa) were measured with a 4-Fr diagnostic or 6-Fr guiding catheter before and after saline flush. The mean Pd/mean Pa (Pd/Pa) and instantaneous wave-free ratio (iFR) were calculated before and after flushing. We compared the effect of flushing on the changes in Pd/Pa and iFR between the 4-Fr diagnostic and 6-Fr guiding catheters. Using the 4-Fr diagnostic catheter, there was a significant decrease in incidence of aortic waveform distortion from 42.0% (47 lesions) before flushing to 1.8% (2 lesions) after flushing (p < 0.001); the incidence was only 3.0% before saline flush and decreased to 0% after saline flush when using the 6-Fr guiding catheter. The presence of aortic waveform distortion influenced the iFR when the 4-Fr system was used. Functional measurements with the 4-Fr diagnostic catheter require adequate saline flush to remove the influence of aortic waveform distortion.

Non-hyperaemic pressure ratios to guide percutaneous coronary intervention.

The use of fractional flow reserve (FFR) in guiding revascularisation improves patient outcomes and has been well-established in clinical guidelines. Despite this, the uptake of FFR has been limited, likely attributable to the perceived increase in procedural time and use of hyperaemic agents that can cause patient discomfort. This has led to the development of instantaneous wave-free ratio (iFR), an alternative non-hyperaemic pressure ratio (NHPR). Since its inception, the use of iFR has been supported by an increasing body of evidence and is now guideline recommended. More recently, other commercially available NHPRs including diastolic hyperaemia-free ratio and resting full-cycle ratio have emerged. Studies have demonstrated that these indices, in addition to mean distal coronary artery pressure to mean aortic pressure ratio, are mathematically analogous (with specific nuances) to iFR. Additionally, there is increasing data demonstrating the equivalent diagnostic performance of alternative NHPRs in comparison with iFR and FFR. These NHPRs are now integral within most current pressure wire systems and are commonly available in the catheter laboratory. It is therefore key to understand the fundamental differences and evidence for NHPRs to guide appropriate clinical decision-making.

Echocardiography in Autoimmune Rheumatic Diseases for Diagnosis and Prognosis of Cardiovascular Complications.

Autoimmune rheumatic diseases are systemic diseases frequently affecting the heart and vessels. The main cardiovascular complications are pericarditis, myocarditis, valvular disease, obstructive coronary artery disease and coronary microcirculatory dysfunction, cardiac failure and pulmonary hypertension. Echocardiography, including transthoracic two and three-dimensional echocardiography, Doppler imaging, myocardial deformation and transesophageal echo, is an established and widely available imaging technique for the identification of cardiovascular manifestations that are crucial for prognosis in rheumatic diseases. Echocardiography is also important for monitoring the impact of drug treatment on cardiac function, coronary microcirculatory function, valvular function and pulmonary artery pressures. In this article we summarize established and evolving knowledge on the role of echocardiography for diagnosis and prognosis of cardiovascular abnormalities in rheumatic diseases.

P5632Different impact of lesion length on fractional flow reserve in intermediate coronary lesions between each coronary artery

Abstract Background Previous studies reported that lesion length was an important geometric parameter in addition to the degree of stenosis in the determinant of functional significance of coronary artery stenosis. Nevertheless, the optimal cutoff value of lesion length for predicting functional significance for each coronary artery has not yet been evaluated, though previous studies revealed that the cutoff value of minimum lumen diameter measured on coronary angiography (CAG) to predict fractional flow reserve (FFR) &lt;0.80 is different for each coronary artery Purpose This study evaluated whether the impact of lesion length on functional significance is similar between each coronary artery for lesions with intermediate stenosis. Methods Patients with suspected coronary artery disease who had at least one intermediate coronary lesion (luminal diameter stenosis of 70 to 80% by visual estimation on CAG) and underwent FFR measurement for the evaluation of myocardial ischemia were evaluated. Quantitative coronary angiography analysis including percent diameter stenosis and lesion length was performed. FFR was measured as the ratio of the mean distal coronary artery pressure to the mean aortic pressure during maximal hyperemia induced by intravenous infusion of adenosine triphosphate (150 μg /kg/min). The area under the receiver operating characteristics (ROC) curve was estimated for the best cutoff value as a predictor of FFR value of ≤0.80 for each coronary artery. Results A total of 221 de novo lesions that underwent FFR measurement were enrolled. The average FFR value was 0.81±0.07. Although lesion length was similar among the lesions with an FFR &gt;0.80 at different locations, the mean lesion length was significantly longer for lesions in the right coronary artery (RCA) with an FFR ≤0.80 than for those in the left anterior descending artery (LAD) and left circumflex artery (13.4±3.4 versus 8.6±3.1 versus 12.0±3.7 mm, p&lt;0.001). ROC analysis demonstrated that the optimal cutoff value of lesion length for predicting an FFR ≤0.80 was 10.0 mm in the LAD (0.56 area under the curve, 48% sensitivity, 76% specificity), whereas 13.1 mm in the RCA (0.84 area under the curve, 67% sensitivity, 93% specificity) (Figure). ROC analysis of LL for FFR≤0.80 Conclusions A longer lesion length is required to achieve FFR&lt;0.80 in the RCA than in the other arteries. This may suggest the low possibility of an FFR ≤0.80 when stenosis is focal and short in the RCA with stenosis of 70 to 80% by visual estimation on CAG.

Validation of Resting Diastolic Pressure Ratio Calculated by a Novel Algorithm and Its Correlation With Distal Coronary Artery Pressure to Aortic Pressure, Instantaneous Wave-Free Ratio, and Fractional Flow Reserve.

Instantaneous wave-free ratio (iFR) offers a reliable non-hyperemic assessment of coronary physiology but requires dedicated proprietary software with a fully automated algorithm. We hypothesized that dPR (diastolic pressure ratio), calculated with novel universal software, has a strong correlation with iFR, similar diagnostic accuracy relative to resting distal coronary artery pressure/aortic pressure and fractional flow reserve (FFR). The dPR study is an observational, retrospective, single-center cohort study including patients who underwent iFR or FFR. Dedicated software was used to calculate the dPR from Digital Imaging and Communications in Medicine (DICOM) pressure waveforms. The flat period on the pressure difference between sample (dP) to the time difference between the same sample points (dt) signal was used to detect automatically the period, where the resistance is low and constant, and to calculate the dPR, which is an average over 5 consecutive heartbeats. The software was validated by correlating iFR results with dPR. Software validation was done by comparing 78 iFR measurements in 44 patients who underwent iFR. Mean iFR and dPR were 0.91±0.10 and 0.92±0.10, respectively, with a significant linear correlation ( R=0.997; P<0.001). Diagnostic accuracy was tested in 100 patients who underwent FFR. Mean FFR, resting distal coronary artery pressure/aortic pressure, and dPR were 0.85±0.09, 0.94±0.05, and 0.93±0.07, respectively. There was a significant linear correlation between dPR and FFR ( R=0.77; P<0.001). Both distal coronary artery pressure/aortic pressure and dPR had good diagnostic accuracy in the identification of lesions with an FFR ≤0.80 (area under the curve, 0.84; 95% CI, 0.76-0.92 and 0.86; 95% CI, 0.78-0.93, respectively). dPR, calculated by a novel validated software tool, showed a strong linear correlation with iFR. dPR correlated well with FFR with a good diagnostic accuracy to identify positive FFR.

Abstract 257: Unselective Pulmonary Vasodilation is an Important Factor in Sodium Nitroprusside Enhanced Cardiopulmonary Resuscitation Improved Blood Flow

Introduction: Sodium nitroprusside enhanced CPR (SNPeCPR) is a novel CPR method that includes a potent vasodilator, active compression-decompression CPR, an inspiratory impedance threshold device and abdominal binding. SNPeCPR has been shown to improve vital organ flow and functional survival outcomes compared to standard CPR methods in animals. We hypothesize that one of the main effects of SNPeCPR mediated increase in cardiac output during prolonged resuscitation is profound pulmonary artery vasodilation. Methods: After electrically induced VF was left untreated for 3 min, 20 (44-48Kg) pigs were randomized to receive SNPeCPR (10) or standard CPR (10) for a total of 30 min; the first 10 minutes were BLS CPR followed by twenty minutes of ACLS. During ACLS, animals were given IV SNP (1mg bolus) or standard epinephrine (0.5mg) q5 min until ROSC or 45 min total CPR. Shocks were delivered after 30 minutes of CPR at 300J. If ROSC was achieved, animal was monitored until 4-hour endpoint. Ventilations were provided with 10ml/kg at 10/min with a mechanical ventilator. Initially during CPR, room air was used and FiO2 was adjusted q5 minutes to maintain O 2 %saturation &amp;gt 92% based on ABG. Lactic acid was also measured. Aortic, right atrial, and coronary artery pressures and carotid blood flow were recorded continuously. A-a oxygen gradient was measured with standard technique. Results: SNPeCPR animals documented a significantly higher mean CPP, lower lactic acid and 3x higher carotid blood flow over 30 minutes compared to standard CPR as previously documented. A-a oxygen gradient was dramatically increased in the SNPeCPR and coincided with a decreased lactate level (see Figure 1). Discussion: SNPeCPR causes profound pulmonary vasodilation and increases flow through non-ventilated lung areas. Despite that, the overall increase in forward flow leads to higher minute O 2 delivery and improved tissue perfusion. SNPeCPR should be used with 100% oxygen in the first human clinical trial.

Pooled diagnostic accuracy of resting distal to aortic coronary pressure referenced to fractional flow reserve: The importance of resting coronary physiology.

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. 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." 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). 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.

Effects of Impella on Coronary Perfusion in Patients With Critical Coronary Artery Stenosis

Mechanical circulatory support devices are used to maintain hemodynamic stability during high-risk percutaneous coronary interventions. Little is known on the effects of such devices on coronary hemodynamics in patients with significant coronary stenosis. We sought to investigate whether mechanical circulatory support in the form of Impella (Abiomed Inc, Danvers, MA) can improve coronary hemodynamics in the presence of a critical coronary stenosis. We examined coronary perfusion pressures and coronary pressure distal to a critical stenosis using a coronary pressure wire in 11 patients (12 coronary lesions) undergoing high-risk percutaneous coronary interventions with the use of mechanical circulatory support. Systemic, ventricular, and coronary hemodynamics were obtained at both minimum and maximum support levels before high-risk percutaneous coronary interventions. All patients had obstructive lesions with angiographically estimated diameter stenosis between 70% and 99% and distal coronary artery pressure to aortic pressure ratios between 0.44 and 0.88. When compared with minimum support, maximum support resulted in a decrease in the left ventricular end-diastolic pressure (27.3±8.6 versus 21.5±5.2 mm Hg; P=0.002) and increases in the mean systemic blood pressure (77.6±13.5 versus 88.2±12.2 mm Hg; P<0.001) and mean distal coronary pressure (51.8±20.2 versus 60.8±18.1 mm Hg; P<0.001). Effective coronary perfusion pressure (mean aortic pressure-left ventricular end-diastolic pressure) significantly increased with maximum support (49.8±15.7 versus 67.2±13.6 mm Hg; P<0.001). Diastolic perfusion pressure (diastolic blood pressure-left ventricular end-diastolic pressure) also significantly increased with maximum support (32.9±13.4 versus 52.0±11.6 mm Hg; P<0.001). Mechanical circulatory support with Impella can improve distal coronary pressure and coronary perfusion pressures in the presence of critical coronary stenosis.

Influence of myocardial oxygen demand on the coronary vascular response to arterial blood gas changes in humans.

It remains unclear if the human coronary vasculature is inherently sensitive to changes in arterial Po2 and Pco2 or if coronary vascular responses are the result of concomitant increases in myocardial O2 consumption/demand ([Formula: see text]). We hypothesized that the coronary vascular response to Po2 and Pco2 would be attenuated in healthy men when [Formula: see text] was attenuated with β1-adrenergic receptor blockade. Healthy men (age: 25 ± 1 yr, n = 11) received intravenous esmolol (β1-adrenergic receptor antagonist) or volume-matched saline in a double-blind, randomized crossover study and were exposed to poikilocapnic hypoxia, isocapnic hypoxia, and hypercapnic hypoxia. Measurements made at baseline and after 5 min of steady state at each gas manipulation included left anterior descending coronary blood velocity (LADV; Doppler echocardiography), heart rate, and arterial blood pressure. LADV values at the end of each hypoxic condition were compared between esmolol and placebo. The rate-pressure product (RPP) and left ventricular mechanical energy (MELV) were calculated as indexes of [Formula: see text]. All gas manipulations augmented RPP, MELV, and LADV, but only RPP and MELV were attenuated (4-18%) after β1-adrenergic receptor blockade ( P < 0.05). Despite attenuated RPP and MELV responses, β1-adrenergic receptor blockade did not attenuate the mean LADV vasodilatory response compared with placebo during poikilocapnic hypoxia (29.4 ± 2.2 vs. 27.3 ± 1.6 cm/s) and isocapnic hypoxia (29.5 ± 1.5 vs. 30.3 ± 2.2 cm/s). Hypercapnic hypoxia elicited a feedforward coronary dilation that was blocked by β1-adrenergic receptor blockade. These results indicate a direct influence of arterial Po2 on coronary vascular regulation that is independent of [Formula: see text]. NEW & NOTEWORTHY In humans, arterial hypoxemia led to an increase in epicardial coronary artery blood velocity. β1-Adrenergic receptor blockade did not diminish the hypoxemic coronary response despite reduced myocardial O2 demand. These data indicate hypoxemia can regulate coronary blood flow independent of myocardial O2 consumption. A plateau in the mean left anterior descending coronary artery blood velocity-rate-pressure product relationship suggested β1-adrenergic receptor-mediated, feedforward epicardial coronary artery dilation. In addition, we observed a synergistic effect of Po2 and Pco2 during hypercapnic hypoxia.

INFLUENCE OF CONCOMITANT CHRONIC TOTAL OCCLUSION AND COLLATERAL FLOW ON SINGLE CUTOFF INSTANTANEOUS WAVE-FREE RATIO ON INTERMEDIATE CORONARY LESIONS: RESULTS FROM A SINGLE-CENTER REGISTRY

The instantaneous wave-free ratio (iFR) is a coronary artery pressure index measured in the wave-free period of diastole in absence of hyperemia. FFR is thought to reflect the size of the territory the vessel provides, but there is limited data with iFR. The purpose of this study is to evaluate the

CRT-100.43 Effect Of Gender Differences On Instantaneous Wave-free Ratio And Fractional Flow Reserve In Intermediate Coronary Lesions: Results From A Single-center Registry

Instantaneous wave-free ratio (iFR) is a newly developed coronary artery pressure index measured in the wave-free period of diastole in absence of hyperemia. An iFR-guided revascularization strategy was shown to be noninferior to fractional flow reserve (FFR)-guided revascularization strategy in