Validation of a novel numerical model to predict regionalized blood flow in the coronary arteries

Aims: Ischaemic heart disease results from insufficient coronary blood flow. Direct measurement of absolute flow (mL/min) is feasible, but has not entered routine clinical practice in most catheterization laboratories. Interventional cardiologists, therefore, rely on surrogate markers of flow. Recently, we described a computational fluid dynamics (CFD) method for predicting flow that differentiates inlet, side branch, and outlet flows during angiography. In the current study, we evaluate a new method that regionalizes flow along the length of the artery. Methods and results: Three-dimensional coronary anatomy was reconstructed from angiograms from 20 patients with chronic coronary syndrome. All flows were computed using CFD by applying the pressure gradient to the reconstructed geometry. Side branch flow was modelled as a porous wall boundary. Side branch flow magnitude was based on morphometric scaling laws with two models: a homogeneous model with flow loss along the entire arterial length; and a regionalized model with flow proportional to local taper. Flow results were validated against invasive measurements of flow by continuous infusion thermodilution (Coroventis™, Abbott). Both methods quantified flow relative to the invasive measures: homogeneous (r 0.47, P 0.006; zero bias; 95% CI -168 to +168 mL/min); regionalized method (r 0.43, P 0.013; zero bias; 95% CI -175 to +175 mL/min). Conclusion: During angiography and pressure wire assessment, coronary flow can now be regionalized and differentiated at the inlet, outlet, and side branches. The effect of epicardial disease on agreement suggests the model may be best targeted at cases with a stenosis close to side branches.</p

High microvascular resistance and reduced left atrial strain in patients with coronary microvascular dysfunction: The micro-strain study

BACKGROUND: It is already known that high coronary microvascular resistance (Rμ) is linked to altered left ventricular stiffness and might be an early indicator of heart failure with preserved ejection fraction (HFpEF). Left atrial dysfunction, on the other hand, varies according to the grade of left ventricular diastolic dysfunction. This is the first study to use the latest development for invasive assessment of Rμ and to combine it with echocardiographic assessment of left atrial strain during reservoir phase (LASr) by speckle tracking in relation to left ventricular (LV) diastolic function. METHODS AND RESULTS: An invasive angiogram was performed in 97 patients because of suspected ANOCA. All patients underwent comprehensive echocardiography, yet image quality was poor in 15 patients leaving 82 patients to include in the final analysis. In order to compare Rμ with LASr values, patients were divided into 4 groups based upon normal values of Rμ as defined by Fournier et al. The mean LASr was plotted against the four resistance groups. The LASr was 48.6% in the lowest resistance group, and 40.1%, 36.3% and 30.1% in the low intermediate, high intermediate and high resistance group respectively. These differences were significant compared to the lowest resistance group (p < 0.05). Although higher Rμ groups showed more diastolic dysfunction, LASr was already decreased irrespective of the severity of diastolic dysfunction. CONCLUSION: This study shows a relationship between increased Rμ and reduced LASr, that seems to precede conventional measures of left ventricular diastolic dysfunction. This suggests that microvascular dysfunction might be an early indicator for the development of impaired LA function

Selective intracoronary hypothermia in patients with ST-elevation myocardial infarction: rationale and design of the EURO-ICE Trial

In ST-elevation myocardial infarction (STEMI), early restoration of blood flow, preferably by primary percutaneous coronary intervention (PPCI), is paramount to limit infarct size (IS) and improve long-term outcomes 1. However, reperfusion by itself may also cause damage to the myocardium and increase IS. This has been termed myocardial reperfusion injury 2. In animal models of acute myocardial infarction, it has been demonstrated that hypothermia decreases IS 3. In contrast, human studies applying systemic cooling methods have not yet been able to confirm this protective effect. Recently, we developed a new method to provide selective intracoronary hypothermia during PPCI 4. The EUROpean Intracoronary Cooling Evaluation in patients with ST-elevation myocardial infarction (EURO-ICE) trial will assess the efficacy of this method. Methods STUDY OBJECTIVES The primary objective of the EURO-ICE trial is to evaluate the effect of selective intracoronary hypothermia (SIH) on IS

Safety of absolute coronary flow and microvascular resistance measurements by thermodilution

Assessment of the microcirculation of the heart has gained interest over recent years. This is partly due to the fact that up to 50% of patients with chest pain visiting the catherization laboratory do not present with significant epicardial stenosis (so-called Angina with Non Obstructive Coronary Artery disease (ANOCA).1 Most knowledge regarding microvascular resistance came from non-invasive imaging, from invasive index of microvascular resistance2, or from doppler wires3, both being semi-quantitative and operator dependent. Recently, direct quantitative measurement of coronary blood flow and microvascular resistance has become possible by thermodilution with saline infusion, using a pressure-temperature guidewire and a multisidehole infusion catheter. Such measurements have been validated versus Positron Emission Tomography (PET)4, have a high reproducibility and are operator independent.5 Procedural safety has been reported before5, but long term safety and absence of late complications have not been described yet. The present study evaluates the safety of absolute flow measurements, both periprocedural, at 30 days and to one year follow-up