Nobuhiro Takasugi

Sleep apnoea induces cardiac electrical instability assessed by T-wave alternans in patients with congestive heart failure

To assess the involvement of sleep apnoea in nocturnal sudden cardiac death (SCD) by evaluating cardiac electrical instability using T‐wave alternans (TWA), a risk marker for lethal cardiac arrhythmias, and severity of sleep apnoea in congestive heart failure (CHF) patients.

Continuous T-wave alternans monitoring to predict impending life-threatening cardiac arrhythmias during emergent coronary reperfusion therapy in patients with acute coronary syndrome

AIMS T-wave alternans (TWA) can precede onset of ventricular tachyarrhythmia (VTA). We evaluated the usefulness of continuous TWA monitoring in ultra-short-term prediction of impending life-threatening VTA upon emergent reperfusion in acute coronary syndrome (ACS) patients. METHODS AND RESULTS Twenty consecutive ACS patients undergoing emergent reperfusion therapy were studied. Continuous ambulatory electrocardiograms (ECGs) (leads V1 and V5) were recorded during emergency room visit and therapy. Peak TWA was determined before and after reperfusion by the modified moving average method. Coronary balloon angioplasty/stenting was successfully performed in 19 patients and intracoronary vasodilator was administered in 1 patient with coronary spasm. Three (15.0%) patients developed VTA requiring cardioversion soon after reperfusion. Peak TWA before reperfusion was higher in patients with VTA than in those without (33.0 ± 4.4 vs. 15.8 ± 4.0 µV, P < 0.001). Two patients with arrhythmia exhibited an upsurge in TWA to 75 and 105 µV before onset of VTA. In the third patient, macroscopic TWA appeared in leads V1-V4 in a 12-lead ECG prior to VTA upon pharmacological resolution of vasospasm, although the ambulatory ECG field of view could not detect the upsurge. CONCLUSION Acute coronary syndrome patients at risk of developing VTA soon after reperfusion exhibit premonitory episodes of increased TWA. Thus, TWA monitoring may be useful for ultra-short-term prediction of life-threatening cardiac arrhythmia risk upon emergent reperfusion in ACS patients. Continuous 12-lead ECGs may be required to optimize detection of TWA, which is regionally specific.

Prevalence of Microvolt T-Wave Alternans in Patients With Long QT Syndrome and Its Association With Torsade de Pointes

Background—Prevalence of microvolt T-wave alternans (TWA) and the strength of its association with torsade de pointes (TdP) history have not been fully investigated in patients with long QT syndrome (LQTS). Methods and Results—Twenty-four–hour continuous 12-lead ECGs were recorded in 10 healthy subjects (5 men; median age, 21.5 years) and 32 patients (13 men; median age, 13 years) with LQTS types 1 (n=18), 2 (n=4), 3 (n=4), and unidentified (n=6). Peak TWA was determined by the Modified Moving Average method. None of the healthy subjects had TWA ≥42 µV. All 8 (100%) LQTS patients with a history of TdP exhibited TWA ≥42 µV, whereas only 14 (58.3%) of the 24 LQTS patients without TdP history reached ≥42 µV (p=0.04). Thus, the 42-µV cut point provided 100% sensitivity and 41.7% specificity for an association with TdP history. In the 22 (68.8%) LQTS patients with TWA ≥42 µV, only 2 (median; interquartile range, 1–3) leads exhibited TWA ≥42 µV. Highest TWA levels were recorded in precordial leads (V1–V6) in 30 (93.8%) patients, most frequently in lead V2 (43.8%). A single ECG lead detected only ⩽63.6% of TWA ≥42 µV episodes, whereas the combined leads V2 to V5 detected 100% of TWA ≥42 µV. Conclusions—Microvolt TWA is far more prevalent in LQTS patients than previously reported and is strongly associated with TdP history. TWA should be monitored from precordial leads in LQTS patients. The use of a limited set of ECG leads in conventional monitoring has led to underestimation of TWA and its association with TdP.

Evaluation of Left Atrial Degeneration for the Prediction of Atrial Fibrillation Usefulness of Integrated Backscatter Transesophageal Echocardiography

OBJECTIVES The purpose of this study was to elucidate the usefulness of integrated backscatter (IBS) transesophageal echocardiography (TEE) for the evaluation of atrial degeneration and clarify whether atrial degeneration predicts the occurrence of atrial fibrillation (AF). BACKGROUND One of the causes of AF is pathological degeneration of the left atrium (LA). However, there is no appropriate method to evaluate degeneration of the LA in the clinical setting. METHODS The IBS images were acquired with TEE with a 4- to 7-MHz transducer. The IBS values were calculated as the average power of the backscattered signal from regions of interest (ROI). In the pathological study, we measured IBS values of 21 left atrial specimens obtained from 10 autopsied hearts. Relative interstitial area in the ROI was automatically calculated by a personal computer. In the clinical study, we measured IBS values of the entire LA wall at 5-mm intervals (except the posterior wall) in 42 patients (18 non-AF patients, 14 paroxysmal AF patients, and 10 chronic AF patients). Each IBS value was color-coded to construct 3-dimensional maps. RESULTS There was a weak correlation between the relative interstitial area and IBS values (r = 0.45, p = 0.038). Average corrected IBS values of total voxels in color-coded maps in the AF group (24.4 +/- 6.4 dB) and the paroxysmal AF group (23.9 +/- 9.6 dB) were significantly greater than those in the non-AF group (15.6 +/- 7.4 dB, p = 0.007), whereas there was no significant difference in LA diameter between the paroxysmal AF group (39.4 +/- 6.5 mm) and the non-AF group (36.7 +/- 5.5 mm). CONCLUSIONS With IBS-TEE, we can identify an increase in atrial degeneration that might predict the occurrence of AF before LA dilation.

Transcatheter embolization by autologous blood clot is useful management for small side branch perforation due to percutaneous coronary intervention guide wire

A 75-year-old man underwent PCI for a bifurcation lesion with 90% stenosis in segment 6 and 75% proximal stenosis in segment 9 of the left coronary artery. We implanted a Duraflex coronary stent into segment 6 and kissing balloon inflation for segments 6 and 9. Although these 2 lesions were adequately dilated, we noticed coronary perforation caused by the guide wire in a small branch of segment 9. We tried to repair the perforation using a small balloon and long inflation, but unfortunately the perforation was not improved. We attempted to occlude the small branch including the perforation site with an autologous blood clot via a wire microcatheter inserted into the small branch. The autologous blood clot was suspended in contrast media and saline. Using this procedure, the small branch of segment 9 was occluded completely and the perforated site was repaired. After the procedure, no significant CPK elevation was detected, and 6 months later, we confirmed that small branch embolization was improved and coronary flow was good. Autologous blood clot is useful to occlude and repair perforations in small side branches of the coronary artery without myocardial damage.

Left atrial pathological degeneration assessed by integrated backscatter transesophageal echocardiography as a predictor of progression to persistent atrial fibrillation: Results from a prospective study of three-years follow-up

BackgroundIt is recognized that one of the causes of atrial fibrillation (AF) is pathological degeneration of the left atrium (LA). However, prospective study that elucidated the relationship between the incidence of persistent AF and pathological degeneration has not been performed. The purpose of this study was to elucidate the usefulness of integrated backscatter (IBS) values for the prediction of progression from paroxysmal AF (PAF) to persistent AF.MethodsWe measured IBS values of the entire LA wall at 5 mm intervals (except the posterior wall) in 27 patients with paroxysmal AF and evaluated progression to persistent AF for three years. IBS values were acquired with transesophageal echocardiography (TEE) using a 4–7 MHz transducer. IBS values were calculated as the average power of the backscattered signal from regions of interest (ROI). Each IBS value was color-coded to construct three dimensional maps.ResultsAverage IBS values of total voxels in color-coded maps in the persistent AF group were significantly greater than those in the non-persistent AF group (25.8 ± 5.0 dB vs. 17.4 ± 10.2 dB, p = 0.047), whereas there was no significant difference in LA diameter between the persistent AF and the non-persistent AF group. There was significant difference in persistent AF-free survival after the baseline measurements in the subjects stratified by IBS value (<20 dB versus ≥20 dB) (univariate Cox regression analysis: hazard ratio: 8.74, p =0.046).ConclusionUsing IBS values measured by TEE, we can identify an increase in atrial degeneration that may predict the occurrence of persistent AF before LA dilation.

In-hospital monitoring of T-wave alternans in a case of amiodarone-induced torsade de pointes: clinical and methodologic insights

We report a case of macroscopic T-wave alternans occurring 30 min before the onset of amiodarone-induced torsade de pointes, illustrating a means to monitor for proarrhythmia.

Sudden reversible pacemaker failure in a patient with cardiac sarcoidosis: an unfortunate case of ventricular septal pacing

We report a case of sudden marked deterioration of ventricular stimulation threshold resulting in pacemaker failure 16 months after a ventricular septal lead implantation for atrioventricular block. Echocardiography revealed septal wall thinning at the electrode-tissue interface, which was not detected pre-operatively. Endomyocardial biopsy confirmed cardiac sarcoidosis. The increased threshold was reversible with prednisolone.

'False-positive' intrathoracic impedance monitor alarm caused by amiodarone-induced hypothyroidism in a patient with cardiac resynchronization therapy-defibrillator.

A 78-year-old female received a cardiac resynchronization therapy-defibrillator equipped with an intrathoracic impedance (ITI) monitor and amiodarone therapy was initiated. A massive and long-lasting decrease in ITI occurred without heart failure (HF) deterioration. Pericardial effusion secondary to amiodarone-induced hypothyroidism may have caused the impedance reduction.

Relationship between T-wave alternans magnitude and T-wave amplitude before the onset of ventricular tachyarrhythmias during emergent reperfusion in acute coronary syndrome patients

We greatly appreciate Dr Madias’ remarks on our recent study demonstrating the usefulness of continuous T-wave alternans (TWA) monitoring in ultra-short-term prediction of impending life-threatening ventricular tachyarrhythmias (VTA) during emergent reperfusion therapy in acute coronary syndrome (ACS) patients.1 He raised an interesting question, namely, was there a relationship between the increase in TWA and the possible increase in T-wave amplitude prior to the occurrence of VTA?2 This question is based on his theory that TWA magnitude is affected …