Morio Shoda

Mapping and Ablation of Idiopathic Ventricular Fibrillation

Background— Ventricular fibrillation is the main mechanism of sudden cardiac death. The feasibility of eliminating recurrent episodes by catheter ablation has not been reported. Methods and Results— Twenty-seven patients without known heart disease (13 men, 14 women, 41±14 years of age) were studied after being resuscitated from recurrent (10±12) episodes of primary idiopathic ventricular fibrillation; 23 had received a defibrillator. The first initiating beat of ventricular fibrillation had an identical electrocardiographic morphology and coupling interval (297±41 ms) to preceding isolated premature beats typically noted in the aftermath of resuscitation. These triggers were localized by mapping the earliest electrical activity and ablated by local radiofrequency delivery. Outcome was assessed by Holter and defibrillator memory interrogation. Premature beats were elicited from the Purkinje conducting system in 23 patients: from the left ventricular septum in 10, from the anterior right ventricle in 9, an...

Role of Purkinje conducting system in triggering of idiopathic ventricular fibrillation

Ventricular fibrillation is the main mechanism of sudden cardiac death, but the source of its spontaneous initiation has not been mapped. 16 patients were investigated by electrography and radiofrequency ablation after resuscitation from recurrent idiopathic ventricular fibrillation. Triggers of ventricular fibrillation originated from various locations within the Purkinje system in 12 patients and from the ordinary myocardial muscle in four. The accuracy of mapping was confirmed by acute elimination of triggers by radiofrequency delivery, and there was no recurrence of ventricular fibrillation in 14 patients. Long-term follow-up is necessary to establish that ablation is curative and avoids use of a defibrillator.

Enhancement of the L-Type Ca2+ Current by Mechanical Stimulation in Single Rabbit Cardiac Myocytes

Anion conductance is known to be activated by mechanical stimulation, such as osmotic cell swelling or cell inflation via the patch pipette, of canine or rabbit cardiac myocytes. The effects of mechanical stimulation on time-dependent currents, however, remain unsettled. Using the whole-cell voltage-clamp method, we have found that mechanical stimuli enhance the L-type Ca2+ current (ICa,L) in rabbit cardiac myocytes. At every membrane potential, ICa,L was reversibly increased by osmotic cell swelling and by cell inflation caused by applying a positive pressure of 10 to 15 cm H2O via the patch pipette. ICa,L was increased during cell inflation by 37 +/- 21% (mean +/- SD, n = 17) in atrial cells and by 37 +/ -8% (n = 7) in sinoatrial node cells in solution containing 2 mmol/L Ca2+. The current-voltage relationship, the inactivation time constant, the steady state inactivation curve, and the conductance properties of ICa,L were all virtually unaffected by mechanical stimulation except for the open probability, which appears to increase. The increase in ICa,L was not dependent on protein kinase A, since an inhibitor peptide of cAMP-dependent protein kinase failed to prevent the increase in ICa,L during mechanical stimuli (n=5). The increase in ICa,L caused by cell inflation was unaffected by the chelation of intracellular Ca2+ by the addition of 10 mmol/L EGTA or 10 mmol/L BAPTA to the pipette solution, suggesting that the effect was not mediated by changes in intracellular Ca2+. Thus, mechanical stimulation due to cell swelling or inflation may itself directly increase ICa,L in rabbit cardiac myocytes.

Mortality Reduction in Relation to Implantable Cardioverter Defibrillator Programming in the Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT)

Background —The benefit of novel ICD programming in reducing inappropriate ICD therapy and mortality was demonstrated in MADIT-RIT. However, the cause of the mortality reduction remains incompletely evaluated. We aimed to identify factors associated with mortality, with focus on ICD therapy and programming in the MADIT-RIT population. Methods and Results —In MADIT-RIT, 1500 patients with a primary prophylactic indication for ICD or CRT-D were randomized to one of three different ICD programming arms: conventional programming (VT-zone ≥170 bpm); high-rate programming (VT-zone ≥200 bpm); and delayed programming (60 sec. delay before therapy≥170 bpm). Multivariate Cox models were used to assess the influence of time-dependent appropriate and inappropriate ICD therapy (shock and/or antitachycardia pacing [ATP]) and randomized programming arm on all-cause mortality. During an average follow-up of 1.4±0.6 years, 71 of 1500 (5%) patients died: cardiac in 40 patients (56.3 %), non-cardiac in 23 patients (32.4%), and unknown in 8 patients (11.3%). Appropriate shocks (Hazard Ratio [HR] = 6.32 [95% CI: 3.13-12.75], p<0.001) and inappropriate therapy (HR=2.61 [1.28-5.31], p=0.01) were significantly associated with an increased mortality risk. There was no evidence of increased mortality risk in patients who experienced appropriate ATP only (HR=1.02 [0.36-2.88], p=0.98). Randomization to conventional programming was identified as an independent predictor of death when compared to patients randomized to high-rate programming (HR=2.0 [1.06-3.71], p=0.03). Conclusions —In the MADIT-RIT trial, appropriate shocks, inappropriate ICD therapy, and randomization to conventional ICD programming were independently associated with an increased mortality risk. Appropriate ATP was not related to an adverse outcome. Clinical Trial Registration —clinicaltrials.gov; Unique Identifier: [NCT00947310][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00947310&atom=%2Fcircae%2Fearly%2F2014%2F08%2F17%2FCIRCEP.114.001623.atomBackground—The benefit of novel implantable cardioverter defibrillator (ICD) programming in reducing inappropriate ICD therapy and mortality was demonstrated in Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT). However, the cause of mortality reduction remains incompletely evaluated. We aimed to identify factors associated with mortality, with focus on ICD therapy and programming in the MADIT-RIT population. Methods and Results—In MADIT-RIT, 1500 patients with a primary prophylactic indication for ICD or cardiac resynchronization therapy with defibrillator were randomized to 1 of 3 different ICD programming arms: conventional programming (ventricular tachycardia zone ≥170 beats per minute), high-rate programming (ventricular tachycardia zone ≥200 beats per minute), and delayed programming (60-second delay before therapy ≥170 beats per minute). Multivariate Cox models were used to assess the influence of time-dependent appropriate and inappropriate ICD therapy (shock and antitachycardia pacing) and randomized programming arm on all-cause mortality. During an average follow-up of 1.4±0.6 years, 71 of 1500 (5%) patients died: cardiac in 40 patients (56.3%), noncardiac in 23 patients (32.4%), and unknown in 8 patients (11.3%). Appropriate shocks (hazard ratio, 6.32; 95% confidence interval, 3.13–12.75; P<0.001) and inappropriate therapy (hazard ratio, 2.61; 95% confidence interval, 1.28–5.31; P=0.01) were significantly associated with an increased mortality risk. There was no evidence of increased mortality risk in patients who experienced appropriate antitachycardia pacing only (hazard ratio, 1.02; 95% confidence interval, 0.36–2.88; P=0.98). Randomization to conventional programming was identified as an independent predictor of death when compared with patients randomized to high-rate programming (hazard ratio, 2.0; 95% confidence interval, 1.06–3.71; P=0.03). Conclusions—In MADIT-RIT, appropriate shocks, inappropriate ICD therapy, and randomization to conventional ICD programming were independently associated with an increased mortality risk. Appropriate antitachycardia pacing was not related to an adverse outcome. Clinical Trial Registration—URL: clinicaltrials.gov Unique identifier: NCT00947310.

Impact of Sleep-Disordered Breathing on Life-Threatening Ventricular Arrhythmia in Heart Failure Patients With Implantable Cardioverter-Defibrillator

It was recognized that sleep-disordered breathing (SDB) is associated with cardiac arrhythmia and sudden cardiac death. However, it was unclear whether the presence of SDB increased the risk of life-threatening ventricular arrhythmia in patients with heart failure (HF) with an implantable cardioverter-defibrillator (ICD). Seventy-one patients with HF and an ICD who were followed up for 180 days after a sleep study were prospectively studied. All patients had an ejection fraction <or=35%. SDB was defined as an apnea-hypopnea index >or=10 events/hour on the sleep study. The frequency of appropriate ICD therapy and the day-night pattern of ICD therapies were compared between patients with and without SDB. SDB was diagnosed in 47 of 71 patients (66%). There were no statistical differences between patients with and without SDB in baseline cardiac function. However, appropriate ICD therapies occurred more frequently in patients with (43%) than without SDB (17%; p = 0.029). On multivariate analysis, the presence of SDB was an independent predictor for appropriate ICD therapy (hazard ratio 4.05, 95% confidence interval 1.20 to 13.65, p = 0.015). Moreover, the rate of total ICD therapy from midnight to 6 A.M. was significantly higher in patients with (34%) than without SDB (13%; p = 0.046). In conclusion, in patients with HF with an ICD, the presence of SDB was common and an independent predictor of life-threatening ventricular arrhythmias that were more likely to occur during sleep.

Mortality Reduction In Relation To ICD Programming In MADIT-RIT

Background —The benefit of novel ICD programming in reducing inappropriate ICD therapy and mortality was demonstrated in MADIT-RIT. However, the cause of the mortality reduction remains incompletely evaluated. We aimed to identify factors associated with mortality, with focus on ICD therapy and programming in the MADIT-RIT population. Methods and Results —In MADIT-RIT, 1500 patients with a primary prophylactic indication for ICD or CRT-D were randomized to one of three different ICD programming arms: conventional programming (VT-zone ≥170 bpm); high-rate programming (VT-zone ≥200 bpm); and delayed programming (60 sec. delay before therapy≥170 bpm). Multivariate Cox models were used to assess the influence of time-dependent appropriate and inappropriate ICD therapy (shock and/or antitachycardia pacing [ATP]) and randomized programming arm on all-cause mortality. During an average follow-up of 1.4±0.6 years, 71 of 1500 (5%) patients died: cardiac in 40 patients (56.3 %), non-cardiac in 23 patients (32.4%), and unknown in 8 patients (11.3%). Appropriate shocks (Hazard Ratio [HR] = 6.32 [95% CI: 3.13-12.75], p<0.001) and inappropriate therapy (HR=2.61 [1.28-5.31], p=0.01) were significantly associated with an increased mortality risk. There was no evidence of increased mortality risk in patients who experienced appropriate ATP only (HR=1.02 [0.36-2.88], p=0.98). Randomization to conventional programming was identified as an independent predictor of death when compared to patients randomized to high-rate programming (HR=2.0 [1.06-3.71], p=0.03). Conclusions —In the MADIT-RIT trial, appropriate shocks, inappropriate ICD therapy, and randomization to conventional ICD programming were independently associated with an increased mortality risk. Appropriate ATP was not related to an adverse outcome. Clinical Trial Registration —clinicaltrials.gov; Unique Identifier: [NCT00947310][1]. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT00947310&atom=%2Fcircae%2Fearly%2F2014%2F08%2F17%2FCIRCEP.114.001623.atomBackground—The benefit of novel implantable cardioverter defibrillator (ICD) programming in reducing inappropriate ICD therapy and mortality was demonstrated in Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT). However, the cause of mortality reduction remains incompletely evaluated. We aimed to identify factors associated with mortality, with focus on ICD therapy and programming in the MADIT-RIT population. Methods and Results—In MADIT-RIT, 1500 patients with a primary prophylactic indication for ICD or cardiac resynchronization therapy with defibrillator were randomized to 1 of 3 different ICD programming arms: conventional programming (ventricular tachycardia zone ≥170 beats per minute), high-rate programming (ventricular tachycardia zone ≥200 beats per minute), and delayed programming (60-second delay before therapy ≥170 beats per minute). Multivariate Cox models were used to assess the influence of time-dependent appropriate and inappropriate ICD therapy (shock and antitachycardia pacing) and randomized programming arm on all-cause mortality. During an average follow-up of 1.4±0.6 years, 71 of 1500 (5%) patients died: cardiac in 40 patients (56.3%), noncardiac in 23 patients (32.4%), and unknown in 8 patients (11.3%). Appropriate shocks (hazard ratio, 6.32; 95% confidence interval, 3.13–12.75; P<0.001) and inappropriate therapy (hazard ratio, 2.61; 95% confidence interval, 1.28–5.31; P=0.01) were significantly associated with an increased mortality risk. There was no evidence of increased mortality risk in patients who experienced appropriate antitachycardia pacing only (hazard ratio, 1.02; 95% confidence interval, 0.36–2.88; P=0.98). Randomization to conventional programming was identified as an independent predictor of death when compared with patients randomized to high-rate programming (hazard ratio, 2.0; 95% confidence interval, 1.06–3.71; P=0.03). Conclusions—In MADIT-RIT, appropriate shocks, inappropriate ICD therapy, and randomization to conventional ICD programming were independently associated with an increased mortality risk. Appropriate antitachycardia pacing was not related to an adverse outcome. Clinical Trial Registration—URL: clinicaltrials.gov Unique identifier: NCT00947310.

Contact Sensitivity to Polychloroparaxylene‐Coated Cardiac Pacemaker

Poly‐chloroparaxylene (parylene) is widely used as a material for cardiac pacemaker coating. Contact sensitivity to parylene was proven by patch test. Wrapping the pacemaker in a polytetrafluoroethylene sheet prior to implantation prevented further skin reactions.

2017 HRS expert consensus statement on cardiovascular implantable electronic device lead management and extraction

Fred M. Kusumoto, MD, FHRS, FACC, Chair, Mark H. Schoenfeld, MD, FHRS, FACC, FAHA, CCDS, Vice-Chair, Bruce L. Wilkoff, MD, FHRS, CCDS, Vice-Chair, Charles I. Berul, MD, FHRS, Ulrika M. Birgersdotter-Green, MD, FHRS, Roger Carrillo, MD, MBA, FHRS, Yong-Mei Cha, MD, Jude Clancy, MD, Jean-Claude Deharo, MD, FESC, Kenneth A. Ellenbogen, MD, FHRS, Derek Exner, MD, MPH, FHRS, Ayman A. Hussein, MD, FACC, Charles Kennergren, MD, PhD, FETCS, FHRS, Andrew Krahn, MD, FRCPC, FHRS, Richard Lee, MD, MBA, Charles J. Love, MD, CCDS, FHRS, FACC, FAHA, Ruth A. Madden, MPH, RN, Hector Alfredo Mazzetti, MD, JoEllyn Carol Moore, MD, FACC, Jeffrey Parsonnet, MD, Kristen K. Patton, MD, Marc A. Rozner, PhD, MD, CCDS, Kimberly A. Selzman, MD, MPH, FHRS, FACC, Morio Shoda, MD, PhD, Komandoor Srivathsan, MD, Neil F. Strathmore, MBBS, FHRS, Charles D. Swerdlow, MD, FHRS, Christine Tompkins, MD, Oussama Wazni, MD, MBA

Prevalence and Persistence of Depression in Patients with Implantable Cardioverter Defibrillator: A 2-year Longitudinal Study

Background: It is unclear whether depression persists in patients with implantable cardioverter defibrillators (ICDs). We evaluated the prevalence and persistence of depression in ICD patients over a 2‐year period.

Correlation between left atrial appendage morphology and flow velocity in patients with paroxysmal atrial fibrillation

AIMS Reduction of left atrial appendage (LAA) flow velocity (FV) is a risk factor for thrombus formation and increases the risk of stroke in patients with atrial fibrillation (AF). Furthermore, LAA morphology is correlated with stroke in patients with AF. The aim of this study was to correlate LAAFV with LAA morphology in patients with AF. METHODS AND RESULTS We studied 96 patients (age 59.0 ± 10.2 years, 75% male) referred for radiofrequency catheter ablation for paroxysmal AF. All patients underwent computed tomography (CT) and transthoracic and transoesophageal echocardiography during sinus rhythm. LAA morphology was classified as one of the four types (chicken wing, windsock, cactus, and cauliflower) on CT images. There were significant differences in LAAFV among LAA morphologies (chicken wing 73.7 ± 21.9 cm/s, windsock 61.9 ± 19.6 cm/s, cactus 55.3 ± 14.1 cm/s, cauliflower 52.7 ± 18.1 cm/s, P = 0.008). Post hoc multiple comparisons showed that LAAFV was higher in patients with chicken wing than in those with cactus (P = 0.006, vs. chicken wing) and cauliflower (P = 0.006, vs. chicken wing), but not with windsock (P = 0.102). After adjustment for clinical and LAA anatomical covariates (orifice area, volume, and trabeculation), multiple linear regression analyses revealed that LAA morphology was an independent determinant of LAAFV [chickens wing: standardized partial regression coefficients (β) = 0.317, P = 0.0014; windsock: β = 0.303, P = 0.038]. CONCLUSION LAA morphology is a significant determinant of LAAFV, suggesting an underlying mechanism for the association between LAA morphology and embolic events.