Enhanced Detection of Left Atrial Spontaneous Echo Contrast by Transthoracic Harmonic Imaging in Mitral Stenosis

BACKGROUND: Spontaneous echo contrast (SEC) of the left atrium (LA) is associated with increased risk of thromboembolism in patients with mitral stenosis(MS). The determination of the presence and severity of LA spontaneous echo contrast(SEC) is of prognostic importance in these patients. Harmonic imaging(HI), a novel echocardiographic technique that differs from conventional fundamental imaging(FI) by transmitting ultrasound at one frequency and receiving at twice the transmitted frequency, produces better endocardial border definition and myocardial opacification. However, there are no data about its value on the detection of LA SEC. The purpose of this study was to investigate the utility of transthoracic noncontrast HI in the detection of LA SEC in patients with. METHODS: Seventy-four consecutive patients with MS (49 female, mean age 51) underwent standard transthoracic echocardiograms (TTE) in both HI and FI and transesophageal echocardiography (TEE) to determine the presence and severity of LA SEC. LA SEC was graded by TEE; mild if only seen at high gain, severe if visible in the entire LA at normal gain control of the equipment. Control subjects comprised of 30 patients randomly selected from patients who did not have LA SEC at TEE examination. RESULTS: Atrial fibrillation was found in 46 patients (62.2%). The mean mitral valve area and mean mitral gradient were 1.0+/-0.3cm2 and 8.2+/-4.1mmHg, respectively. Nine patients (12.2%) had episodes of systemic embolism; stroke in 8 and peripheral embolism in 1. LA thrombus was found in 11 patients (14.9%) by TEE. LA SEC was present in all but one patient by TEE (mild in 35, severe in 38 patients). FI of TTE, however, revealed LA SEC in only 5 (6.8%) of the 73 patients. In contrast, in HI, LA SEC could be detected in 63 (86.3%) of the 73 patients. In the detection of severe LA SEC, the sensitivity of FI and HI were 13.2% (5/38) and 100% (38/38), respectively. LA SEC was not observed in control subjects either by FI or HI. CONCLUSION: Transthoracic HI significantly enhances the detection of LA SEC in patients with MS.

Clinical utility of harmonic imaging in the detection of right to left shunt through patent foramen ovale by transthoracic contrast echocardiography

BACKGROUND: Paradoxical embolism through the patent foramen ovale (PFO) is a well-recognized mechanism for otherwise unexplained ischemic stroke. Although transthoracic contrast echocardiography (TCE) has been used frequently for noninvasive diagnosis of right to left shunt through PFO, its diagnostic accuracy appears limited, especially in patients with poor acoustic window. Since harmonic imaging (HI) can enhance the definition of contrast microbubbles, theoretical advantages of HI in the detection of right to left shunt through PFO using microbubbles can be considered. However, there are few data regarding the diagnostic efficacy of HI in the detection of right to left shunt through PFO. The purpose of this study was to compare the diagnostic value of transthoracic HI in the detection of right to left shunt through PFO in patients with stroke with that of fundamental imaging (FI). Methods: One hundred thirty-six consecutive patients with stroke (82 male, mean age:9) underwent TCE in both HI and FI and transesophageal echocardiography (TEE) during rest and Valsalva maneuver with intravenous administration of agitated saline. PFO was judged to be present if microbubbles appeared in the left atrium within 3 cardiac cycles of their appearance in the right atrium. TEE was regarded as the gold standard for assessing the diagnostic accuracy of TCE. Results: Right to left shunt through PFO was detected in 40 of 136 patients by TEE (29.4%). FI of TCE detected shunt through PFO in only 9 of 136 patients (6.6%). In contrast, HI detected shunt through PFO in 25 of 136 patients (18.4%). The overall sensitivity and specificity of FI and HI for detection of right to left shunt through PFO were 22.5%, 62.5% (p<0.05) and 100%, 100%, respectively. Valsalva maneuver during HI significantly increased the detection rate of shunt through PFO (during rest in 9 and during Valsalva maneuver in 25, p<0.05). CONCLUSION: HI with contrast microbubble injection significantly enhanced the detection of right to left shunt through PFO in patients with ischemic stroke compared with FI by transthoracic approach.

Assessment of the anti-Xa activities of Low Molecular Weight Heparins in Patients with Acute Coronary Syndrome

BACKGROUND AND OBJECTIVES: Standard unfractionated heparin (UFH) has long been used to prevent death and myocardial infarction in patients with acute coronary syndrome and acute occlusion undergoing percutaneous revascularization. However, UFH binds to several plasma proteins, platelets, and endothelial cells producing a highly variable anticoagulant response. In contrast, Low molecular weight heparin (LMWH) exhibits less protein binding and provides more predictable anticoagulant response with reduced need for patient monitoring and dosage adjustment. The purpose of this study was to assess the anti-Xa activities of LMWH in Korean patients with acute coronary syndrome after recommended dose for caucasians and to determine an optimal method of administration of LMWH. MATERIALS AND METHODS: Twenty five patients with acute coronary syndrome were enrolled and allocated to five separate groups (5 patients in each group) by types according to molecular weight (LMWH (A): (molecular weight of 4500 daltons, LMWH (B): molecular weight of 6400 daltons) and methods of administration (Group 1A and 1B: Subcutaneous and subcutaneous injections (SC-SC), Group 2: Intravenous and subcutaneous injections (IV-SC), Group 3A and 3B: Intravenous, subcutaneous and subcutaneous injections (IV-SC-SC). Five groups were as follows: Group 1A: LMWH (A) 1 mg/kg SC every 12 hours, Group 1B: LMWH (B) 100 IU/kg SC every 12 hours, Group 2: LMWH (A) 1 mg/kg IV bolus and 1 mg/kg SC 12 hours later, Group 3A: LMWH (A) 0.5 mg/kg IV bolus, 3 hours later 1 mg/kg SC every 12 hours, Group 3B: LMWH (B) 50 IU/kg IV bolus, 3 hours later 100 IU/kg SC every 12 hours. Anti-Xa activity was measured by amidolytic assay method (Rotachrome, Stago, France) in 555 samples from 25 patients. All the data of anti-Xa activity in each group were plotted along the sequential time and mean values of them were analyzed by Wilcoxon signed rank test. RESULTS: 1)The anti-Xa activity (mean 0.6216+/-0.238 IU/mL) of LMWH (A) was greater than that of LMWH (B)(mean 0.2587+/-0.1709 IU/mL) in the conventional SC-SC method (p<0.001). 2) The anti-Xa activity of LMWH (A) (mean 0.6203+/-0.2383 IU/mL) was also greater than that of LMWH (B)(mean 0.468+/-0.2428 IU/mL) in the IV-SC-SC method (p<0.001). 3) More rapid and effective anti-Xa activities were achieved by IV-SC-SC method compared with conventional SC-SC method. CONCLUSION: This study suggests that immediate achievement and optimum maintenance of anticoagulant activity can be accomplished by IV-SC-SC method rather than conventional SC-SC method in patients of acute coronary syndrome.

Cathrter Aboation of The Posteroseptal Accessory Pathways

BACKGROUND: The ablation of accessory pathways(APs) using radiofrequency(RF) energy has been establihed as a primary modality of treatment for atrioventricular reentranr tachycardia with probrn safety and high rate of success. However, the ablation of posteroseptal(PS) APs had been recognized as being more difficult to ablate than those in other location because of the complex three dimensional anatony of the posterior apace, and multifarious approaches have been proposed. We analyzed electrophysiologic characteristics and results of catheter ablation of 70 consecutive patients, who underwent RF ablation of PS APs with or without booster direct current(DC) shock. METHODS: Teh AP location was confirmed to be in the PS region, ablation was attepmted at the atrial aspect of the tricuspid annulus adjacent to the coronary sinus ostium, within the coronary sinus in couding middle cardiac vein, or underneath the mitral annulus close to the septum using retrograde transaortic approach if deemed necessory. A continuous, unmodulated sine wave radiofr-equency generator was used as the source of energy for ablation. The site was considered optimal for ablation when the electrogram obtained from the ablation catheter had one or more of the following characteristics : (1) short VA intervals with an A : V ratio of