Relationship of myocardial substrate characteristics as assessed by myocardial perfusion imaging and cardiac reverse remodeling levels after cardiac resynchronization therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) can provide cardiac reverse remodeling (RR), which may include mechanical reverse remodeling (MRR) and/or electrical reverse remodeling (ERR). However, uncoupling of MRR and ERR is not uncommon, and the underlying mechanisms are not clear. This study aimed to evaluate the relationship of myocardial substrate characteristics as assessed by myocardial perfusion imaging (MPI) and cardiac RR post-CRT. MATERIALS AND METHODS: Forty-one patients (26 men, mean age 66 ± 10 years) with heart failure received CRT for at least 12 months were assigned to three groups according to their levels of RR: I, MRR + ERR (ESV reduced ≥15 % and intrinsic QRS duration reduced ≥10 ms); II, MRR only (ESV reduced ≥15 %); and III, non-responder (the others). All the patients also underwent MPI under transient CRT-off to evaluate the intrinsic myocardial substrates, including myocardial scar, LV volumes and function, systolic dyssynchrony, and activation sequences. In addition, ventricular tachycardia (VT) and ventricular fibrillation (VF) detected by the CRT devices during follow-up periods were also recorded. RESULTS: Quantitative analysis of MPI showed that there were significant differences for scar burden [15.9 ± 9.5, 26.8 ± 16.1, and 45.6 ± 15.1 % for group I (n = 15), II (n = 16), and III (n = 10), respectively, p < 0.001], EDV (136.6 ± 64.9, 221.6 ± 123.9, and 351.8 ± 216.3 ml, p = 0.002), ESV (82.6 ± 59.8, 172.3 ± 117.2, and 293.3 ± 209.6 ml, p = 0.001), LVEF (44.9 ± 15.0, 25.6 ± 10.9, and 21.5 ± 11.7 %, p < 0.001), systolic phase SD (23.4° ± 10.3°, 36.0° ± 16.2°, and 57.0° ± 22.2°, p < 0.001), and bandwidth (72.5° ± 31.1°, 113.4° ± 56.4°, and 199.1° ± 90.1°, p < 0.001). Myocardial scar interfered with the normal propagation of mechanical activation, resulting in heterogeneous activation sequences. Compared with group II (MRR only), group I (ERR + MRR) had significantly less initial activation segments (1.9 ± 1.0 vs. 2.6 ± 0.7, p < 0.05) and shorter maximal contraction delay (46.9° ± 12.9° vs. 58.8° ± 18.5°, p < 0.05). During the periods of follow-up, 21 patients developed VT/VF, including only 1 patient (1 VT) in group I (6.7 %), 8 patients (7 VT and 1 VF) in group II (50 %), and 9 patients (7 VT and 5 VF) in group III (90 %). CONCLUSION: The characteristics of myocardial substrates as assessed by MPI differed significantly between different levels of cardiac RR post-CRT. Myocardial scar played an important role in the development of ERR. Different cardiac RR levels contributed to different incidences of ventricular arrhythmia, and the combination of ERR and MRR provided highest anti-arrhythmic effects.

Novel tips for engaging the coronary sinus guided by right ventricular lead.

AIMS: This study investigated the relationship between the ostia of the coronary sinus (CS) and the tricuspid annulus (TA) for CS cannulation using a right ventricular (RV) lead, which could map out the TA by forming a curve when placed at the apex or low septum. METHODS AND RESULTS: Seventy patients (45 males, 67 ± 12 years) who were admitted for CRT device implant were included in the evaluation of the relationship between the CS ostia and TA. An electrophysiological (EP) mapping catheter was used to probe the CS. The ostium was shown by the CS venography at the left anterior oblique (LAO) 20° and caudal 20°. Local electrograms were collected with CS catheters in the CS or RV. Transthoracic echocardiography was evaluated before each procedure. All CS ostia were located within 3.75 cm around the tip of TA. Sixty-two subjects (Group I, 89%) had CS ostia located under the TA. Eight patients (Group II) with CS ostia over the TA revealed larger left ventricular (LV) size and a smaller ratio of left atrium (LA)/LV size. LV enlargement predicted the presence of CS ostia over the TA. Typical CS electrograms were used to further confirm if the EP catheter was in the CS in all the subjects. CONCLUSION: Use of the RV lead revealed that the CS ostia had a close relationship with the TA.

Flow-injection enzymatic analysis for glycerol and triacylglycerol.

A flow-injection enzymatic analytical system was developed for determination of glycerol and triacylglycerol based on enzymatic reactions in capillary followed by electrochemical detection. The hydrogen peroxide produced from the enzyme reaction was monitored by a platinum-based electrochemical probe. Different immobilization strategies on silica support were studied. The best and most effective configuration found for the measurement of glycerol and triacylglycerols in this system was the tandem connection of a lipase column and a silica-fused capillary column coimmobilized with glycerokinase (GK) and glycerol-3-phosphate oxidase (GPO). Lipase helps the breakdown of triacylglycerol to yield free fatty acids and glycerol, while glycerokinase catalyzes the adenosine-5-triphosphate-dependent phosphorylation of glycerol to yield alpha-glycerol phosphate, which can subsequently be oxidized by 3-glycerol phosphate oxidase to produce hydrogen peroxide. Response-surface methodology (RSM) was applied to optimize the proposed system for glycerol. Experiment settings were designed by central composite design to investigate the combined effects of pH, flow rate, reaction temperature, and ATP concentration on collected signals. The fitted model, per RSM, showed that the optimum conditions of the system are 2 mM ATP in 0.1 M carbonate buffer (pH 11.0), flow rate of 0.18 mL/min, temperature of 35 degrees C, 20 microL of sample injection, and applied voltage of 0.650 V. The proposed biosensing system using lipase, GK, and GPO exhibited a flow-injection analysis peak response of 2.5 min and a detection limit of 5 x 10(-5) M glycerol (S/N = 3) with acceptable reproducibility (CV < 4.30%). It also had linear working ranges from 10(-4) to 10(-2) M for glycerol and from 10(-3) to 10(-2) M for triacylglycerol. The capillary enzyme reactor was stable up to 2 months in continuous operation, and it was possible to analyze up to 15 samples per hour. The present biosensing system holds promise for on-line detection of triacylglycerol in serum and glycerol content in fermented products.