Keiichi Inada

Brigham and Women's Hospital, Boston, Massachusetts, United States

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Publications (76)233.94 Total impact

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    ABSTRACT: A 40-year-old female presented at our hospital because of heart palpitations. During an electrophysiological study, atrioventricular (AV) conduction showed dual AV nodal physiology. Three types of supraventricular tachycardia (SVT) were induced. The initiation of SVT was reproducibility dependent on a critical A-H interval prolongation. An early premature atrial contraction during SVT repeatedly advanced the immediate His potential with termination of the tachycardia, indicating AV node reentrant tachycardia (AVNRT). However, after atrial overdrive pacing during SVT without termination of the tachycardia, the first return electrogram resulted in an AHHA response, consistent with junctional tachycardia. The mechanism of paradoxical responses to pacing maneuvers differentiating AVNRT and junctional tachycardia was discussed.
    Heart and vessels. 09/2014;
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    ABSTRACT: A 57-year-old male with persistent atrial fibrillation (AF) was referred for catheter ablation. Multidetector computed tomography (MDCT) revealed that a membrane divided the left atrium into two chambers, thus indicating the presence of cor triatriatum sinister. A 3D image reconstructed by MDCT showed that the accessory atrium received the left common and the right side PVs, as if it were a total common trunk, and this then flowed into the main atrium. After isolation of the pulmonary vein and posterior wall from the left atrium, AF could not be induced by any programmed pacing. The patient has remained free from AF during the 1 year of follow-up.
    Heart and Vessels 09/2014; · 2.13 Impact Factor
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    ABSTRACT: -Catheter ablation for ventricular tachycardia (VT) from structural heart disease has a significant risk of recurrence, but the optimal duration for in hospital monitoring is not defined. This study assesses the timing, correlates, and prognostic significance of early VT recurrence after ablation.
    Circulation Arrhythmia and Electrophysiology 08/2014; · 5.95 Impact Factor
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    ABSTRACT: -Catheter ablation (CA) for ventricular arrhythmia (VA) near the distal great cardiac vein (GCV) is often challenging and data are limited.
    Circulation Arrhythmia and Electrophysiology 08/2014; · 5.95 Impact Factor
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    IJC Heart & Vessels. 01/2014; 2:21–23.
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    ABSTRACT: Open-irrigated radiofrequency catheter ablation (oiRFA) of atrial fibrillation (AF) imposes a volume load and risk of pulmonary edema. We sought to assess the effect of volume administration during ablation on left atrial (LA) pressure and B-type natriuretic peptide (BNP). LA pressure was measured via transseptal sheath at the beginning and end of 44 LA ablation procedures in 42 patients. BNP plasma levels were measured before and after 10 procedures. A median of 3,255 (interquartile range [IQR], 2,014)-mL saline was administered during the procedure. During LA ablation, the median fluid balance was +1,438 (IQR, 1,109) mL and LA pressure increased by median 3.7 (IQR, 5.9) mm Hg (P < 0.001). LA pressure did not change in the 19 procedures with furosemide administration (median ΔP = -0.3 [IQR, 7.1] mm Hg, P = 0.334). The correlation of LA pressure and fluid balance was weak (rs = 0.383, P = 0.021). BNP decreased in all four procedures starting in AF or atrial tachycardia and then converting to sinus rhythm (P = 0.068), and increased in all six procedures starting and finishing in sinus rhythm (P = 0.028). After ablation, symptomatic volume overload responding to diuresis occurred in three patients. A substantial intravascular volume load during oiRFA can be absorbed with little change in LA pressure, such that LA pressure is not a reliable indicator of the fluid balance. Subsequent redistribution of the volume load imposes a risk after the procedure. Conversion to sinus rhythm may improve ability to acutely accommodate the volume load.
    Pacing and Clinical Electrophysiology 12/2013; · 1.75 Impact Factor
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    ABSTRACT: -In the absence of overt structural heart disease most left ventricular outflow tract (LVOT) ventricular tachycardias (VTs) have a focal origin and are benign. We hypothesized that multiple morphologies (MM) of inducible LVOT VT may indicate a scar-related VT that can mimic idiopathic VT. -Of 54 consecutive patients referred for ablation of sustained OT VT without overt structural heart disease 24 had LVOT VT; 10 had MMVT and 14 had a single VT (SM). The MM group were older (70.3±4.3 vs. 53.9±15.9 years p=0.004), had more hypertension (100% vs. 29%, P=0.0006), had longer PR intervals and QRS durations than the SM group. In contrast to the SM group, the MM group VTs had features consistent with reentry including induction by programmed stimulation without isoproterenol, entrainment in some and abnormal electrograms in the periaortic area. Periaortic region voltages suggested scar in the MM group, but not the SM group. Magnetic resonance imaging in 2 MM patients was consistent with scar, but not in 10 SM patients. Longer radiofrequency applications were required in the MM group than the SM group. At a median follow-up of 9.7 (3.0, 32.0) months, recurrences tended to be more frequent in the MM group than the SM group (70% vs. 22%, P=0.07). -VTs from small regions of periaortic scar can mimic idiopathic VT but are suggested by multiple VT morphologies and are more difficult to ablate. Whether these patients are at greater risk, as feared for other scar-related VTs, warrants further study.
    Circulation Arrhythmia and Electrophysiology 12/2013; · 5.95 Impact Factor
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    ABSTRACT: Objectives This study sought to determine the relevance of echocardiographic assessment focusing on right ventricular (RV) function to estimate prognosis in patients with heart failure (HF) and low left ventricular ejection fraction (LVEF) after ablation of ventricular tachycardia (VT). Background Recurrent VT is a marker of increased mortality in HF. Decision making remains challenging as some patients have a poor outcome despite successful catheter ablation of VT due to progressive biventricular HF. Methods Retrospective analysis was performed on data from 320 consecutive patients with HF and LVEF ≤40% who underwent ablation for recurrent VT between 1999 and 2008. Baseline clinical and echocardiographic data were analyzed in relation to survival. Results Among the 320 patients included, the mean age was 63 years, and 86% were male. During follow-up (median: 36 months) 127 patients (40%) died. RV dysfunction (hazard ratio [HR]: 1.4) and tricuspid regurgitation (TR) (HR: 1.7), together with age, New York Heart Association (NYHA) class, and serum creatinine, were independent predictors of death in a Cox regression model. Mortality was more than 2-fold higher in patients with at least moderate RV dysfunction and TR (HR: 2.6; p < 0.001). In patients with at least moderate RV dysfunction, TR, and estimated pulmonary arterial pressure ≥45 mm Hg, mortality was 61% at 2 years, compared with 16% in patients with good RV function without pulmonary hypertension (p < 0.0001). Conclusions Despite low LVEF, patients with recurrent VT who had good RV function without elevated pulmonary pressures had a good prognosis after VT ablation. RV dysfunction, TR, and elevated pulmonary pressures identified a high-risk group of VT survivors in whom additional interventions may be necessary to improve survival.
    JACC Heart Failure. 08/2013; 1(4):281-289.
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    ABSTRACT: AIMS: Although patients with paroxysmal atrial fibrillation (AF) and prolonged sinus pauses [tachycardia-bradycardia syndrome (TBS)] are generally treated by permanent pacemaker, catheter ablation has been reported to be a curative therapy for TBS without pacemaker implantation. The purpose of this study was to define the potential role of successful ablation in patients with TBS.METHODS AND RESULTS: Of 280 paroxysmal AF patients undergoing ablation, 37 TBS patients with both AF and symptomatic sinus pauses (age: 62 ± 8 years; mean maximum pauses: 6 ± 2 s) were analysed. During the 5.8 ± 1.2 years (range: 5-8.7 years) follow-up, both tachyarrhythmia and bradycardia were eliminated by a single procedure in 19 of 37 (51%) patients. Repeat procedures were performed in 14 of 18 patients with tachyarrhythmia recurrence (second: 12 and third: 2 patients). During the repeat procedure, 79% (45 of 57) of previously isolated pulmonary veins (PVs) were reconnected to the left atrium. Pulmonary vein tachycardia initiating the AF was found in 46% (17 of 37) and 43% (6 of 14) of patients during the initial and second procedure, respectively. Finally, 32 (86%) patients remained free from AF after the last procedure. Three patients (8%) required pacemaker implantation, one for the gradual progression of sinus dysfunction during a period of 6.5 years and the others for recurrence of TBS 3.5 and 5.5 years after ablation, respectively.CONCLUSION: Catheter ablation can eliminate both AF and prolonged sinus pauses in the majority of TBS patients. Nevertheless, such patients should be continuously followed-up, because gradual progression of sinus node dysfunction can occur after a long period of time.
    Europace 06/2013; · 2.77 Impact Factor
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    ABSTRACT: BACKGROUND: Acute end points of catheter ablation for ventricular tachycardia (VT) remain incompletely defined. The aim of this study is to identify causes for failure in patients with structural heart disease and to assess the relation of this acute outcome to longer-term management and outcomes. METHODS AND RESULTS: From 2002 to 2010, 518 consecutive patients (84% male, 62±14 years) with structural heart disease underwent a first ablation procedure for sustained VT at our institution. Acute ablation failure was defined as persistent inducibility of a clinical VT. Acute ablation failure was seen in 52 (10%) patients. Causes for failure were: intramural free wall VT in 13 (25%), deep septal VT in 9 (17%), decision not to ablate due to proximity to the bundle of His, left phrenic nerve, or a coronary artery in 3 (6%), and endocardial ablation failure with inability or decision not to attempt to access the epicardium in 27 (52%) patients. In multivariable analysis, ablation failure was an independent predictor of mortality (hazard ratio 2.010, 95% CI 1.147 to 3.239, P=0.004) and VT recurrence (hazard ratio 2.385, 95% CI 1.642 to 3.466, P<0.001). CONCLUSIONS: With endocardial or epicardial ablation, or both, acute ablation failure was seen in 10% of patients, largely due to anatomic factors. Persistence of a clinical VT is associated with recurrence and comparatively higher mortality.
    Journal of the American Heart Association. 01/2013; 2(3):e000072.
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    ABSTRACT: We present the case of a patient who developed regular, narrow QRS tachycardia after ablation for long-standing persistent atrial fibrillation. During the electrophysiological study, this tachycardia was diagnosed as macroreentrant atrial tachycardia circulating around the mitral annulus. Catheter ablation was performed to treat the tachycardia by targeting the linear region between the annulus and the left inferior pulmonary vein. Although linear radiofrequency application along the mitral isthmus (MI) line resulted in the termination of this tachycardia, a unidirectional conduction block was observed through the MI. Bidirectional conduction block was subsequently achieved by delivering supplemental radiofrequency energies at the gap on the MI.
    Journal of Arrhythmia 01/2013; 29(5):270–274.
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    ABSTRACT: Analysis of unipolar voltage maps has been used to detect epicardial scar, but data to define optimal parameters to identify scar remote from the recording site is limited. This study compares the characteristics of electrograms at endocardial sites adjacent to abnormal epicardial sites. Data obtained from endocardial and epicardial electroanatomical maps of 31 patients with scar-related ventricular tachycardia were reviewed. Five hundred twenty-three pairs of endo- and epicardial points were selected according to predefined criteria. The endocardial points adjacent to epicardial scar (bipolar voltage <1.5 mV) had smaller unipolar voltage than those distant from epicardial scar (P<0.001). In multivariable analysis, unipolar voltage was the only endocardial electrogram predictor of epicardial scar (P<0.001, OR 0.94, 95% CI 0.93 to 0.97). An endocardial unipolar amplitude <4.4 mV in the right ventricular (RV) (sensitivity 93%, specificity 76%) and <5.1 mV in the left ventricular (LV) (sensitivity 91%, specificity 75%) was the optimal cutoff predicting epicardial scar. Applying these thresholds to electroanatomical maps, revealed a good match between endocardial unipolar abnormality and epicardial scar for 67% of LV and 75% of RV maps, respectively, but notably poor matches occurred in 8 (29%) maps (7 with nonischemic cardiomyopathy). Site-by-site correlations were better for ischemic than nonischemic cardiomyopathy. This study supports the contention that unipolar electrograms are capable of indicating overlying epicardial scar during endocardial mapping, but illustrates limitations that appear to differ with nonischemic as compared to ischemic cardiomyopathy. The presence of epicardial arrhythmia substrate cannot be excluded by analysis of unipolar endocardial maps in some patients.
    Journal of the American Heart Association. 01/2013; 2(5):e000215.
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    ABSTRACT: Thrombin, the final coagulation product of the coagulation cascade, has been demonstrated to have many physiological effects, including pro-fibrotic actions via protease-activated receptor (PAR)-1. Recent investigations have demonstrated that activation of the cardiac local coagulation system was associated with atrial fibrillation. However, the distribution of thrombin in the heart, especially difference between the atria and the ventricle, remains to be clarified. We herein investigated the expression of thrombin and other related proteins, as well as tissue fibrosis, in the human left atria and left ventricle. We examined the expression of thrombin and other related molecules in the autopsied hearts of patients with and without atrial fibrillation. An immunohistochemical analysis was performed in the left atria and the left ventricle. The thrombin was immunohistologically detected in both the left atria and the left ventricles. Other than in the myocardium, the expression of thrombin was observed in the endocardium and the subendocardium of the left atrium. Thrombin was more highly expressed in the left atrium compared to the left ventricle, which was concomitant with more tissue fibrosis and inflammation, as detected by CD68 expression, in the left atrium. We also confirmed the expression of prothrombin in the left atrium. The expression of PAR-1 was observed in the endocardium, subendocardium and myocardium in the left atrium. In patients with atrial fibrillation, strong thrombin expression was observed in the left atrium. The strong expression levels of thrombin, prothrombin and PAR-1 were demonstrated in the atrial tissues of human autopsied hearts.
    PLoS ONE 01/2013; 8(6):e65817. · 3.53 Impact Factor
  • Journal of Arrhythmia 01/2013; 29(5):302–304.
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    ABSTRACT: Ablation Multiform Fascicular Tachycardia. Introduction: Fascicular tachycardia (FT) is an uncommon cause of monomorphic sustained ventricular tachycardia (VT). We describe 6 cases of FT with multiform QRS morphologies. Methods and Results : Six of 823 consecutive VT cases were retrospectively analyzed and found attributable to FT with multiform QRS patterns, with 3 cases exhibiting narrow QRS VT as well. All underwent electrophysiology study including fascicular potential mapping, entrainment pacing, and electroanatomic mapping. The first 3 cases describe similar multiform VT patterns with successful ablation in the upper mid septum. Initially, a right bundle branch block (RBBB) VT with superior axis was induced. Radiofrequency catheter ablation (RFCA) targeting the left posterior fascicle (LPF) resulted in a second VT with RBBB inferior axis. RFCA in the upper septum just apical to the LBB potential abolished VT in all cases. Cases 4 and 5 showed RBBB VT with alternating fascicular block compatible with upper septal dependent VT, resulting in bundle branch reentrant VT (BBRT) after ablation of LPF and left anterior fascicle (LAF). Finally, Cases 5 and 6 demonstrated spontaneous shift in QRS morphology during VT, implicating participation of a third fascicle. In Case 6, successful ablation was achieved over the proximal LAF, likely representing insertion of the auxiliary fascicle near the proximal LAF. Conclusions : Multiform FTs show a reentrant mechanism using multiple fascicular branches. We hypothesize that retrograde conduction over the septal fascicle produces alternate fascicular patterns as well as narrow VT forms. Ablation of the respective fascicle was successful in abolishing FT but does not preclude development of BBRT unless septal fascicle is targeted and ablated. (J Cardiovasc Electrophysiol, Vol. pp. 1-8).
    Journal of Cardiovascular Electrophysiology 09/2012; · 3.48 Impact Factor
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    ABSTRACT: The magnitude of improvement of acute heart failure achieved during treatment varies greatly among patients. We examined changes in the plasma B-type natriuretic peptide (BNP) levels of patients with acute heart failure and attempted to elucidate the clinical factors associated with amelioration of acute heart failure. The study population consisted of 208 consecutive patients admitted to our institution with acute heart failure. We measured plasma BNP levels before and after treatment of acute heart failure and evaluated these levels based on median age, body mass index (BMI), creatinine (Cr) level, and left ventricular ejection fraction (EF). Plasma BNP levels before treatment were equivalent between the younger and older age groups; however, plasma BNP levels after treatment were higher in the older age group (p<0.01). Plasma BNP levels before treatment were significantly high in the lower BMI group (p<0.05) and the higher Cr group (p<0.01). Similarly, plasma BNP levels after treatment were high in both the lower BMI and higher Cr groups (p<0.01 for both). In the low EF group, plasma BNP levels before treatment were significantly high (p<0.01), while plasma BNP levels after treatment were equivalent to those in the high EF group. A multiple linear regression analysis revealed that Cr was positively correlated and BMI and EF were negatively correlated with plasma BNP levels before treatment; however, the contributions of age, BMI, and Cr in reducing plasma BNP levels were more significant after treatment. The contributions of clinical factors working against amelioration of heart failure vary before and after treatment. Regarding plasma BNP levels, older age, very low BMI, and the presence of renal dysfunction eventually act to prevent amelioration of acute heart failure. Systolic dysfunction does not act against amelioration of acute heart failure.
    European heart journal. Acute cardiovascular care. 09/2012; 1(3):240-7.
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    ABSTRACT: Background- Catheter ablation of ventricular tachycardia (VT) in nonischemic heart diseases can be challenging, and outcomes across different diseases are incompletely defined. The aim of this study was to describe the outcomes after catheter ablation for nonischemic VT in a large cohort and to compare the electrophysiological findings and outcomes according to the type of underlying disease. Methods and Results- Of the 891 consecutive patients undergoing catheter ablation for ventricular arrhythmias, 226 patients (52±14 years; 79% men) with sustained VT due to nonischemic heart disease were included. The primary end point was all-cause death or heart transplantation. Secondary end points were a composite of death, heart transplantation, or readmission because of VT recurrence within 1 year of discharge. Underlying heart diseases were dilated cardiomyopathy in 119 (53%), valvular heart disease in 34 (15%), arrhythmogenic right ventricular cardiomyopathy in 37 (16%), congenital heart disease in 16 (7%), cardiac sarcoidosis in 13 (6%), and hypertrophic cardiomyopathy in 7 (3%) patients. After ablation, inability to induce any VT was achieved in 55%, and another 20% had inducible VTs modified. Major complications occurred in 5%. Arrhythmogenic right ventricular cardiomyopathy had better outcomes than dilated cardiomyopathy for primary (P=0.002) and secondary end points (P=0.004). Sarcoidosis had worse outcome than dilated cardiomyopathy for secondary end point (P=0.002). At 1 year after the last ablation (a mean of 1.4±0.6 procedures, 1-4), freedom from death, heart transplantation, and readmission for VT recurrence were achieved in 173 (77%) patients. Conclusions- In patients with recurrent VT due to nonischemic heart disease, catheter ablation is often useful, although the outcome varies according to the nature of the underlying heart disease.
    Circulation Arrhythmia and Electrophysiology 08/2012; 5(5):992-1000. · 5.95 Impact Factor
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    ABSTRACT: Plasma B-type natriuretic peptide (BNP) is finely regulated by the cardiac function and several extracardiac factors. Therefore, the relationship between the plasma BNP levels and the severity of heart failure sometimes seems inconsistent. The purpose of the present study was to investigate the plasma BNP levels in patients with cardiac tamponade and their changes after pericardial drainage. This study included 14 patients with cardiac tamponade who underwent pericardiocentesis. The cardiac tamponade was due to malignant diseases in 13 patients and uremia in 1 patient. The plasma BNP levels were measured before and 24-48 h after drainage. Although the patients reported severe symptoms of heart failure, their plasma BNP levels were only 71.2 ± 11.1 pg/ml before drainage. After appropriate drainage, the plasma BNP levels increased to 186.0 ± 22.5 pg/ml, which was significantly higher than that before drainage (P = 0.0002). In patients with cardiac tamponade, the plasma BNP levels were low, probably because of impaired ventricular stretching, and the levels significantly increased in response to the primary condition after drainage. This study demonstrates an additional condition that affects the relationship between the plasma BNP levels and cardiac function. If inconsistency is seen in the relationship between the plasma BNP levels and clinical signs of heart failure, the presence of cardiac tamponade should therefore be considered.
    Heart and Vessels 08/2012; · 2.13 Impact Factor
  • International journal of cardiology 07/2012; · 6.18 Impact Factor
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    ABSTRACT: PV and Linear Ablation for CFAEs.  Linear ablations in the left atrium (LA), in addition to pulmonary vein (PV) isolation, have been demonstrated to be an effective ablation strategy in patients with persistent atrial fibrillation (PsAF). This study investigated the impact of LA linear ablation on the complex-fractionated atrial electrograms (CFAEs) of PsAF patients. A total of 40 consecutive PsAF patients (age: 54 ± 10 years, 39 males) who underwent catheter ablation were enrolled in this study. Linear ablation of both roofline between the right and left superior PVs and the mitral isthmus line joining from the mitral annulus to the left inferior PV were performed following PV isolation during AF. High-density automated CFAE mapping was performed using the NAVX, and maps were obtained 3 times during the procedure (prior to ablation, after PV isolation, and after linear ablations) and were compared. PsAF was terminated by ablation in 13 of 40 patients. The mean total LA surface area and baseline CFAEs area were 120.8 ± 23.6 and 88.0 ± 23.5 cm(2) (74.2%), respectively. After PV isolation and linear ablations in the LA, the area of CFAEs area was reduced to 71.6 ± 22.6 cm(2) (58.7%) (P < 0.001) and 44.9 ± 23.0 cm(2) (39.2%) (P < 0.001), respectively. The LA linear ablations resulted in a significant reduction of the CFAEs area percentage in the region remote from ablation sites (from 56.3 ± 20.6 cm(2) (59.6%) to 40.4 ± 16.5 cm(2) (42.9%), P < 0.0001). Both PV isolation and LA linear ablations diminished the CFAEs in PsAF patients, suggesting substrate modification by PV and linear ablations. (J Cardiovasc Electrophysiol, Vol. 23, pp. 962-970, September 2012).
    Journal of Cardiovascular Electrophysiology 04/2012; 23(9):962-70. · 3.48 Impact Factor

Publication Stats

384 Citations
233.94 Total Impact Points

Institutions

  • 2009–2014
    • Brigham and Women's Hospital
      • • Department of Medicine
      • • Center for Brain Mind Medicine
      Boston, Massachusetts, United States
  • 2003–2014
    • The Jikei University School of Medicine
      • • Division of Cardiology
      • • Department of Internal Medicine H
      Edo, Tōkyō, Japan
  • 2009–2013
    • Harvard Medical School
      • Department of Medicine
      Boston, Massachusetts, United States