Itaru Yokouchi

Catheter Ablation for an Incessant Form of Antiarrhythmic Drug-Resistant Ventricular Fibrillation After Acute Coronary Syndrome

A 77‐year‐old man was admitted with an acute coronary syndrome (ACS), severe heart failure (HF), and repeated ventricular fibrillation (VF) episodes. A single premature ventricular complex (PVC) induced ventricular tachycardia (VT), which degenerated to VF reproducibly. This PVC was eliminated by catheter ablation at the left ventricular posteroseptal region where double Purkinje potentials preceding the ventricular wave had been recorded. The electrical storm disappeared, and programmable stimulation failed to induce any tachyarrhythmias after the ablation. A Purkinje fiber network‐related PVC served as a trigger and as a substrate for VT and VF in a case of ACS with HF.

Aggressive statin therapy in multicenter and effectiveness for the reduction of intra-myocardial damage caused by non-ST elevation acute coronary syndrome: AMERICA study

Background: While preprocedural statin treatment for acute coronary syndrome (ACS) is widely regarded as beneficial, there has been no prospective randomized multicenter trial of patients with non-ST elevation ACS in the Japanese population to examine the efficacy of preprocedural aggressive statin use. The aim of this study was to confirm this effect by prospective randomized multicenter design. Methods: Fifty patients who presented with non-ST elevation ACS were enrolled, and randomly assigned to aggressive statin administration before percutaneous coronary intervention (PCI). Troponin-T (TnT), creatine phosphokinase (CK), CK-myocardial band (CK-MB), high-sense C-reactive protein (hs-CRP), and brain natriuretic peptide (BNP) were measured at baseline and/ or after procedure. Results: Three days after PCI, the statin group had significantly less CK elevation compared with the nonstatin group (84±17 IU/l versus 180±68 IU/l, respectively, p = 0.02). CK-MB elevation also tended to be lower in the statin group than in the nonstatin group (3.2±1.9 versus. 7.0±3.0, respectively, p = 0.07), as was BNP level (3.2±1.9 versus 7.0±3.0 pg/ml, respectively, p = 0.07). The change of serum LDL cholesterol was significantly correlated with CK (p = 0.01) and TnT (p = 0.02) at 1 day after PCI. Conclusions: Aggressive statin usage before PCI to Japanese patients with non-ST elevation ACS appears to reduce myocardial damage after procedure. The degree of serum lipid level reduction may reflect the vulnerability of atheromatous plaques that could cause cardiac damage after PCI.

Distribution of ultrasonic radiofrequency signal amplitude detects lipids in atherosclerotic plaque of coronary arteries: an ex-vivo study

BackgroundAccumulation of lipids within coronary plaques is an important process in disease progression. However, gray-scale intravascular ultrasound images cannot detect plaque lipids effectively. Radiofrequency signal analysis could provide more accurate information on preclinical coronary plaques.MethodsWe analyzed 29 zones of mild atheroma in human coronary arteries acquired at autopsy. Two histologic groups, i.e., plaques with a lipid core (group L) and plaques without a lipid core (group N), were analyzed by automatic calculation of integrated backscatter. One hundred regions of interest were set on the target zone. Radiofrequency signals from a 50 MHz transducer were digitized at 240 MHz with 12-bit resolution. The intensity of integrated backscatter and its distribution within each plaque were compared between the two groups.ResultsAlthough the mean backscatter was similar between the groups, intraplaque variation of backscatter and backscatter in the axial direction were larger in group L than in group N (p = 0.02). Conventional intravascular ultrasound showed extremely low sensitivity for lipid detection, despite a high specificity. In contrast, a cut-off value>32 for the total variance of integrated backscatter identified lipid-containing plaque with a high sensitivity (85%) and specificity (75%).ConclusionCompared with conventional imaging, assessment of the intraplaque distribution of integrated backscatter is more effective for detecting lipid. As coronary atheroma progresses, its composition becomes heterogeneous and multi-layered. This radiofrequency technique can portray complex plaque histology and can detect the early stage of plaque progression.

Exercise-Ankle Brachial Pressure Index with One-Minute Treadmill Walking in Patients on Maintenance Hemodialysis

BACKGROUND The ankle-brachial pressure index (ABI) is widely used as a standard screening method for arterial occlusive lesion above the knee. However, the sensitivity of ABI is low in hemodialysis (HD) patients. Exercise stress (Ex-ABI) may reduce the false negative results. PATIENTS AND METHODS After measuring resting ABI and toe-brachial pressure index (TBI), ankle pressure and ABI immediately after walking (Post-AP, Post-ABI) were measured using one-minute treadmill walking in 52 lower limbs of 26 HD patients. The definition of peripheral arterial occlusive disease (PAD) required an ABI value of less than 0.90, TBI value of less than 0.60, and decrease of more than 15% of the Post-ABI value and 20 mmHg of Post-AP in Ex-ABI. Computed tomographic angiography (CTA) was performed in 32 lower limbs of 16 HD patients. PAD is defined as presence of stenosis of more than 75% in the case of lesions from an iliac artery to knee on CTA. RESULTS The accuracy of Ex-ABI (Sensitivity, 85.7%; Specificity, 77.7%) was higher than those of ABI (Sensitivity, 42.9%; Specificity, 83.3%) or TBI (Sensitivity, 78.6%; Specificity, 61.1%). CONCLUSION Ex-ABI with one-minute treadmill walking is the most useful tool for the screening of arterial occlusive lesions above the knee in maintenance HD patients.

Focal ablation for atrial fibrillation originating from the inferior vena cava and the posterior left atrium

We identified a case of paroxysmal atrial fibrillation (AF) originating from inferior vena cava (IVC) and the low-posterior left atrium (LA). Both foci, the IVC and the low-posterior LA, simultaneously served not only as trigger but also as driver for maintenance of AF. During AF, the IVC and the low-posterior LA continuously demonstrated the rapid and fractionated potentials that exit into both atria with conduction block. Focal ablation for ectopic beats within the IVC and the low-posterior LA completely eliminated the storm of AF.

Two atrial reentrant tachycardias originating from the superior vena cava : Electrophysiological characteristics and radiofrequency ablation

A case with two different types of atrial reentrant tachycardia of superior vena cava (SVC) origin is presented. Recent clinical studies have shown that the origin of focal atrial tachycardia typically lies in the venous structures connecting to both atria—the coronary sinus, the superior and inferior vena cava, and the pulmonary vein. These foci have atrial muscle fiber extensions which have electrophysiological characteristics essential to generation of focal ectopic firing. However, little is known about reentrant mechanism of these venous structures. In this report, we present a case of two atrial tachycardias (SVT1 and SVT2) independently originating from the SVC. SVT1 had 430 ms of tachycardia cycle length, and SVT2 had 390 ms of tachycardia cycle length. Both of them showed the character of reentry, and their earliest activations were recorded in the SVC. They were successfully eliminated by focal radiofrequency ablation in the SVC.

Endovascular treatment of innominate artery stenosis via the bilateral brachial approach

Endovascular treatment (stenting) has evolved as an effective and safe treatment modality for symptomatic subclavian and innominate artery disease. Most of these patients have comorbid conditions associated with atherosclerotic vascular disease, which is responsible for the access site and increased difficulty of procedure. We report a case of symptomatic innominate artery stenosis with concomitant atherosclerotic disease of the abdominal aorta successfully treated with using coronary devices and the pull-through technique via the bilateral brachial approach.

Comparison of Diagnostic Accuracy between Pulse Volume Recording Parameters and Exercise-Ankle-Brachial Pressure Index in Patients with Ankle-Brachial Pressure Index above 0.91

Objective: The objective of this study was to clarify whether or not pulse volume recoding (PVR) parameters have screening capability equivalent to ankle-brachial pressure index after walking (Ex-ABI) for patients with 0.91 or higher ABI. Patients and Methods: The subjects were 87 patients (147 limbs) with symptoms of lower extremities with 0.91 or higher ABI. In all patients, upstroke time (UT), percentage of mean artery pressure (%MAP) of PVR and Ex-ABI were measured, and computed tomographic angiography (CTA) was concomitantly performed. Results: Area under the curve (AUC) of receiver operating characteristics (ROC) curves of Ex-ABI, %MAP, and UT were 0.90, 0.70, and 0.81, respectively. A significant difference was noted in AUC between Ex-ABI and %MAP (p <0.001). When the cut-off values were set at %MAP ≥45% and UT ≥180 msec, the accuracies of %MAP and UT were markedly lower than that of Ex-ABI. When the cut-off values were corrected to the values determined from the ROC curves (%MAP ≥41, UT ≥164 msec), the diagnostic accuracy of UT increased markedly. Conclusion: In patients with 0.91 or higher ABI, screening capability of PVR parameters was markedly lower than that of Ex-ABI, but UT has screening capability close to that of Ex-ABI when the cut-off value is corrected downward.

Relationship between Insulin Levels and Coronary Atherosclerosis in Newly Diagnosed Diabetes Mellitus and Impaired Glucose Tolerance

Background: While some therapies implemented for newly diagnosed Diabetes Mellitus (DM) or impaired Glucose Tolerance (IGT) are effective in preventing cardiovascular events, investigations of coronary plaque in patients with newly diagnosed DM or IGT are lacking. Methods: We evaluated 96 patients with acute coronary syndrome. The External Elastic Membrane (EEM), Lumen Cross-Sectional Area (CSA), plaque CSA, and plaque burden in the Left Anterior Descending (LAD) artery proximal to the lesion, diagnosed as normal by Coronary Angiography (CAG), were measured using Intravascular Ultrasound (IVUS). Patients were divided according to DM status (DM=35, non-DM=61). Non-DM patients underwent a 75g Oral Glucose Tolerance Test (OGTT) and were further divided into abnormal glucose tolerance (AGT; n=29) and Normal Glucose Tolerance (NGT) groups (n=32). Results: Quantitative Coronary Angiography (QCA) showed no significant differences in EEM or vessel diameter between groups. However, the lumen CSA was significantly smaller in the DM group than in the NGT group. The plaque CSA and plaque burden were significantly greater in the DM and AGT groups than in the NGT group. Total insulin and glucose values and insulin and glucose values at 120 min after the OGTT correlated with plaque CSA; insulin values at 120 min after the OGTT showed the strongest correlation (R=0.505, P<0.01). Conclusions: Coronary plaque was identified among newly diagnosed DM or IGT patients even when the CAG appeared normal, suggesting that preventive measures against atherosclerosis should be initiated prior to DM development.