Particular Morphology of Inferior Pulmonary Veins and Difficulty of Cryoballoon Ablation in Patients With Paroxysmal Atrial Fibrillation.

BACKGROUND: The CRYO-Japan PMS study indicated that cryoballoon ablation (Cryo-Abl) has a lower acute success rate of pulmonary vein isolation (PVI) for the right and left inferior PVs (RIPV and LIPV, respectively) than for the superior PVs. This study aimed to determine if the orientation and position of the inferior PVs are related to the difficulty of acute success of PVI.Methods and Results:We investigated 30 consecutive patients who underwent Cryo-Abl. A "difficult PV" was defined as the requirement for >2 cooling applications and/or touch-up ablation to achieve PVI. We measured the ventral angle between the vertical line and the direction of each PV trunk (PV angle) on the transverse plane of enhanced CT images. PV position was defined as the difference in the levels between the bottom of the RIPVs and the non-coronary cusp of the aorta. PV angle <105° and PV position <1.250 mm were independent factors of difficult RIPV isolation (PV angle: odds ratio (OR)=23.80, confidence interval (CI) -3.15528 to -0.53622, P=0.002; PV position: OR=12.14, CI -2.77301 to -0.23160, P=0.014). PV position <16.875 mm was also related to the difficulty of LIPV isolation (OR=5.78, CI -1.77095 to -0.09474, P=0.027). CONCLUSIONS: RIPV with ventral orientation may require difficult maneuvers to advance an ablation system towards it. Low take-off of the inferior PVs may cause non-coaxial configuration of balloon catheters towards the direction of these veins.

A novel method to estimate blood flow velocity in the left atrial appendage using enhanced computed tomography: role of Hounsfield unit density ratio at two distinct points within the left atrial appendage.

Low blood flow velocity in the left atrial appendage (LAA) indicates a high risk of thromboembolism. Although transesophageal echocardiography (TEE) has been the standard method with which to evaluate the LAA blood flow velocity, a clinically noninvasive method is desired. We hypothesized that the ratio of the Hounsfield unit (HU) density at two distinct points within the LAA represents the blood flow velocity in the LAA. We retrospectively investigated 60 consecutive patients with atrial fibrillation (paroxysmal type, n = 29) who underwent enhanced computed tomography (CT) and TEE. The peak emptying flow velocity in the LAA (LAAPV) was evaluated using TEE. HU density was measured at proximal and distal sites of the LAA (LAAp and LAAd) on CT images. The LAAd/LAAp ratio was correlated with the LAAPV (P < 0.01, r = 0.69). Among several indices, the HU ratio was the most significant parameter associated with the LAAPV (ß = 0.469, CI 28.602-68.286, P < 0.001). Receiver-operating characteristic analysis (area under the curve, 0.91) demonstrated that an HU density ratio cutoff of 0.32 discriminated a low LAAPV (<25 cm/s) with sensitivity of 90% and specificity of 84%. Flow velocity of the LAA can be estimated by the HU density ratio at distal and proximal sites within the LAA. Our method might be a feasible substitution for TEE to discriminate patients with a reduced LAAPV.

Successful Catheter Ablation for Paroxysmal Atrial Fibrillation in a Patient with Double-chambered Right Ventricle.

We herein describe an adult case of double-chambered right ventricle (DCRV) with symptomatic drug-intolerant paroxysmal atrial fibrillation (PAf). The woman was referred to undergo radiofrequency ablation (RFA), and mapping of the pulmonary veins (PVs) demonstrated that a spontaneous spike potential originating from the left inferior PV (LIPV) induced sustained Af in the second procedure. Accordingly, the LIPV was regarded as the arrhythmogenic PV. Since complete isolation of the PVs, the sinus rhythm has been maintained for at least two years. This is the first report to describe that RFA for drug-intolerant PAf was useful in a patient with DCRV.

Cardiac memory-induced T wave change during complete atrioventricular block in a patient with inferior acute myocardial infarction.

Cardiac memory is an electrocardiographic manifestation of transient T wave abnormalities, which is observed after abrupt interruption of abnormal ventricular activation. We report a case with preexisting complete left bundle branch block in whom cardiac memory was induced. This cardiac memory was induced by normalization of QRS morphology after development of complete atrioventricular block due to acute inferior myocardial infarction. .

Intravenous amiodarone homogeneously prolongs ventricular repolarization in patients with life-threatening ventricular tachyarrhythmia.

BACKGROUND: The most critical adverse effects of class III drugs are marked QT prolongation and torsade de pointes. Even though intravenous amiodarone (iv-Amio) is a representative class III drug, it peculiarly inhibits both clinical ventricular tachycardia/fibrillation (VT/VF) and proarrhythmic effects. To test the hypothesis that iv-Amio homogeneously prolongs repolarization, we evaluated electrocardiographic changes before and during short-term amiodarone therapy, focusing closely on the ventricular dispersion of repolarization. METHODS: Twenty-seven consecutive patients treated with iv-Amio for VT/VF as a first-line antiarrhythmic therapy were enrolled in this study. Twelve-lead electrocardiography was recorded before and during amiodarone therapy to evaluate the following electrocardiographic intervals: R-R, QRS, QT, QRS to T-peak (QTp), and T-peak to T-end (Tp-e; as an index of dispersion of repolarization). Repolarization indices were corrected to the heart rate by Bazett's method (QTc, c-QTp, c-Tp-e). RESULTS: Amiodarone suppressed VT/VF in 19/27 (70%) patients without conferring any proarrhythmic effect. The QTc, c-QTp, and R-R interval were significantly prolonged during amiodarone (476±45ms vs 511±45ms, p<0.05; 338±40ms vs 364±35ms, p<0.05; 762±272ms vs 870±189ms, p<0.05; respectively), whereas the c-Tp-e and QRS durations did not change significantly (139±33ms vs 145±41ms, p=0.25; 96±20ms vs 97±21ms, p=0.33; respectively). CONCLUSIONS: Iv-Amio homogeneously prolongs repolarization and properly inhibits original VT/VF recurrence without inducing torsade de pointes.

Efficacy and feasibility of the submuscular implantation technique for an implantable cardiac electrical device.

BACKGROUND: A common complication associated with implantable cardiac electrical device implantation compromises skin lesions caused by overstretching just above a buried device that is relatively large in size. Apart from affecting the cosmetic appearance in some patients, a compromised blood supply to the skin may also lead to ischemic necrosis, which is an important complication. We describe a novel procedure for the implantation of implantable cardiac electrical devices generators under the pectoralis major muscle to avoid such skin-related complications. METHODS: Twenty-one patients were referred to plastic surgeon for surgical support for the secondary replacement of implantable cardiac electrical devices. In all cases, the leads and devices had been implanted under the skin. We decided to perform device implantation under the pectoralis major muscle, which was highly recommended in all these patients. RESULTS: In Japan, leanness is determined on the basis of body mass index less than 18.5, and 11 patients out of 21 (52%) were considered to be lean. The surgeon's participation in the procedure for implantable cardiac electrical device implantation did not exceed 5 minutes in total. CONCLUSIONS: We consider that the novel method of sub-pectoralis major muscle device implantation described here minimizes the risk of the skin breakdown and improves the patient's quality of life.

Simultaneous existence of sustained double chamber tachycardias originating from the aortic sinus of Valsalva.

Monomorphic ventricular tachycardia is basically a benign phenomenon in patients without structural heart disease. The focal source of the tachycardia is usually located in the right ventricular outflow tract and more rarely in the left ventricular outflow tract. Aortic sinus of Valsalva (ASV) is a well-known source of atrial and ventricular tachycardias. We report a case with simultaneous existence of sustained atrial and ventricular tachycardias originating from ASV, which was successfully treated with radiofrequency catheter ablation.

Cardiac resynchronization therapy to prevent life-threatening arrhythmias in patients with congestive heart failure.

Various clinical data demonstrate that cardiac resynchronization therapy (CRT) provides a favorable structural as well as electrical remodeling. The CArdiac Resynchronization-Heart Failure study, which tested the pure effect of CRT (using CRT devices without the capability of defibrillation) clearly showed a significant reduction in the total mortality by partly preventing sudden cardiac death. The antiarrhythmic effects of CRT are explained, at least in part, by ionic and genetic modulation of ventricular myocytes. It has been revealed in animal experiments to mimic disorganized ventricular contraction that CRT reverses down-regulation of certain K(+) channels and abnormal Ca(2+) homeostasis in the failing heart. However, CRT can be proarrhythmic in some particular cases especially in the early phase of this therapy. According to our study, proarrhythmic effects after CRT can be observed in approximately 10% of patients. The relatively high incidence of the proarrhythmic effects of CRT may promote a trend toward selecting CRT-D rather than CRT-P.

Rhythm control should be better for the management of patients with atrial fibrillation and heart failure--rhythm control vs. rate control: which is better in the management of atrial fibrillation? (Rhythm-side).

The incidence of atrial fibrillation (AF) increases with advancing NHYA cardiac functional class, and it significantly affects the cardiac function of a failing heart. In such situations, clinicians should aim to maintain sinus rhythm in these patients with heart failure (HF) in order to improve their prognosis. However, according to various randomized clinical studies demonstrating the non-superiority of rhythm control over rate control, many clinicians seem to prefer to take the line of least resistance (ie, rate control). Curative catheter ablation mainly based on isolation procedure of the pulmonary veins in patients with AF and HF has demonstrated a significant improvement in left ventricular function, even in the presence of adequate ventricular rate control before the ablation. On the other hand, ablation and biventricular pacing therapy, which is an extreme rate control strategy, has not shown any beneficial effects for these patients. Therefore, a regular RR interval with an appropriate cycle length only is not sufficient to improve cardiac performance, and maintenance of sinus rhythm, which restores atrial contraction and the atrioventricular synchrony, is thought to be essential for an improvement in HF. Thoughtful clinicians should do their best to find a way to keep HF patients in sinus rhythm.