Electrocardiography Predictive Value on Coronary Slow Flow Phenomenon

Coronary Slow Flow Phenomenon (CSFP) is characterized by the slow flow of contrast in one or more epicardial coronary vessels without evidence of coronary artery stenosis during coronary angiography procedures. CSFP is fairly common at the time of elective angiography with an incidence of around 7% and accounts for about 4% of hospitalized unstable angina cases. Coronary angiography is currently still the only effective way to detect CSFP, but this procedure is an invasive procedure with high costs, there is a risk of allergy to contrast. Electrocardiography (ECG), as a widely available, inexpensive, and simple modality is felt to be an attractive alternative in early detection of this abnormality. The ECG parameters on CSFP discussed in this study include; p-wave dispersion, QT interval dispersion, QRS intrinsic (Tpeak-Tenddeflection duration), and QRS fragmentation. Further studies are needed on the ECG image in CSFP so that in the future ECG can be a cheaper and non-invasive diagnostic modality for CSFP compared to coronary angiography.

Novel Use of Dual Guiding Catheters Technique to Prevent Distal Embolization and Slow Flow during PCI of Coronary Stent Thrombosis

Despite having an incidence of 0.5 to 2%, stent thrombosis has an in-hospital mortality of 15% and myocardial infarction (MI) incidence of 67%. Even with the usage of thrombus aspiration devices and microvasculature vasodilators such as nitroprusside, verapamil, adenosine, and Gp2b/3a inhibitors, the angiographic result of percutaneous coronary intervention of coronary stent thrombosis remains frequently suboptimal due to distal embolization and subsequent slow flow. We describe a novel use of dual guide catheter technique, where one guide acts as conduit for thrombus aspiration catheter and the other for distal placement of balloon trap to prevent distal embolization while managing a case of coronary stent thrombosis to improve the angiographic outcome in this scenario.

Safety of low-dose dobutamine stress test in coronary slow flow phenomenon

Purpose: To investigate the feasibility and safety of a low-dose dobutamine stress test in coronary slow flow phenomenon (CSFP) patients.Methods: One hundred and forty-two CSFP patients, and forty-four patients without CSFP or significant epicardial coronary stenosis who served as the control group, were retrospectively reviewed. All patients were infused intravenously with dobutamine at an initial infusion rate of 5 μg/kg/min which was then increased at 8-min intervals to 10, 15, and 20 μg/kg/min. Symptoms and echocardiography were monitored simultaneously.Results: Patient tolerance decreased as the doses of dobutamine increased. No termination of the test occurred without dobutamine or at the infusion rate of 5 μg/kg/min. Nonetheless, when the infusion rates were adjusted to 15 and 20 μg/kg/min, the incident of side effects reached up to 30.9 %, and a few patients experienced ST-segment depression in precordial electrocardiographic leads. There were no induced arrhythmias without dobutamine, while the incidence of arrhythmias was highest at the infusion rate of 20 μg/kg/min. Malignant arrhythmias such as ventricular fibrillation and sustained ventricular tachycardia, were not detected. No significant differences were showed in echocardiogram result for left ventricular ejection fraction (LVEF) between CSFP and control group (63.7±7.9 in the CSFP group, versus 64.3±7.2 in the control group; p = 0.63).Conclusion: A low-dose dobutamine stress test is safe and feasible in CSFP patients.

Effects of passive storage on modelling hydrological function and isotope dynamics in a karst flow system in southwest China

Representing passive storage in coupled flow-isotope models can facilitate simulation of mixing and retardation effects on tracer transport in many natural systems, such as catchments or rivers. However, the effectiveness of incorporating passive storages in models of complex karst flow systems remains poorly understood. In this study, we developed a coupled flow-isotope model that conceptually represents both “fast” and “slow” flow processes in heterogeneous aquifers to represent hydrological connections between hillslopes and low-lying depression units in cockpit karst landscapes. As this model originally included a varying number of passive storages at different positions of the flow system (e.g. fast/slow flow reservoirs combined with different hillslope/depression units), the model structure and relevant parameters were optimized using a multi-objective optimization algorithm. This was used to match detailed observational data of hydrological processes and isotope concentration in the Chenqi catchment in southwest China. Results show that the optimal structure for a coupled flow-isotope model incorporated only two passive storages in fast flow and slow flow paths of the hillslope unit. Using fewer or greater numbers of passive stores in the model could lead to under- or over-mixing of isotope signatures. This optimized model structure could effectively improve simulation accuracies for outlet discharge and isotope signatures, with > 0.65 of the modified Kling-Gupta efficiency. Additionally, the optimal tracer-aided model yields reasonable parameter values and estimations of hydrological components (e.g. more than 80 % of fast flow in the total discharge). Furthermore, results imply that the solute transport is primarily controlled by advection and hydrodynamic dispersion in steep hillslope unit, which is a remarkable phenomenon in the karst flow system. The study resulted in new insights, more realistic catchment conceptualizations and improved model formulation.