Preoperative Prediction of Shock Impedance for Subcutaneous Implantable Cardioverter Defibrillator Using Chest Computed Tomography.

BACKGROUND: High shock impedance is associated with conversion failure among patients with subcutaneous implantable cardioverter defibrillators (S-ICD). Currently, there is no preoperative assessment method for predicting high shock impedance. This study examined the efficacy of chest computed tomography (CT) as a preoperative evaluation tool to assess the shock impedance of S-ICDs. METHODS AND RESULTS: The amount of adipose tissue adjacent to the device and anteroposterior diameter at the basal heart region were measured preoperatively using chest CT. We examined the correlation between these measurements and shock impedance at the conversion test. We enrolled 43 patients with S-ICDs (mean [±SD] age 54±15 years; body mass index 23±4 kg/m2; PRAETORIAN score 30-270 points; amount of adipose tissue 1,250±716 cm3), who underwent intraoperative conversion tests by inducing ventricular fibrillation, which was terminated with a 65-J shock. A sufficient concordance correlation coefficient was observed between the shock impedance and the amount of adipose tissue (r=0.616, P<0.01) and anteroposterior diameter (r=0.645, P<0.01). In multiple regression analysis, the amount of adipose tissue (ß=0.439, P=0.009) and anteroposterior diameter (ß=0.344, P=0.038) were identified as independent predictive factors of shock impedance. CONCLUSIONS: The preoperative CT-measured amount of adipose tissue and basal heart anteroposterior diameter are independent predictors of shock impedance. These parameters may be more accurate in identifying higher shock impedance in patients with S-ICDs.

Novel Device-Based Algorithm Provides Optimal Hemodynamics During Exercise in Patients With Cardiac Resynchronization Therapy.

BACKGROUND: An adaptive cardiac resynchronization therapy (aCRT) algorithm has been described for synchronized left ventricular (LV) pacing and continuous optimization of cardiac resynchronization therapy (CRT). However, there are few algorithmic data on the effect of changes during exercise.Methods and Results:We enrolled 27 patients with availability of the aCRT algorithm. Eligible patients were manually programmed to optimal atrioventricular (AV) and interventricular (VV) delays by using echocardiograms at rest or during 2 stages of supine bicycle exercise. We compared the maximum cardiac output between manual echo-optimization and aCRT-on during each phase. After initiating exercise, the optimal AV delay progressively shortened (P<0.05) with incremental exercise levels. The manual-optimized settings and aCRT resulted in similar cardiac performance, as demonstrated by a high concordance correlation coefficient between the LV outflow tract velocity time integral (LVOT-VTI) during each exercise stage (Ex.1: r=0.94 P<0.0008, Ex.2: r=0.88 P<0.001, respectively). Synchronized LV-only pacing in patients with normal AV conduction could provide a higher LVOT-VTI as compared with manual-optimized conventional biventricular pacing at peak exercise (P<0.05). CONCLUSIONS: The aCRT algorithm was physiologically sound during exercise by patients.

Effects of propofol on ventricular repolarization and incidence of malignant arrhythmias in adults.

BACKGROUND: Propofol is commonly used for procedural sedation in interventional electrophysiology. However, ventricular arrhythmias under Propofol have been reported. Our aim was to investigate ventricular repolarization and incidence of ventricular arrhythmias under Propofol infusion in adults with cardiac arrhythmias. METHODS: QRS, QTcB (Bazett), QTcFri (Fridericia), JTc, measurement of T peak to Tend time (Tp-e) at baseline and under Propofol infusion was performed in 235 patients. Screening for unexpected ventricular arrhythmias was performed in 1165 patients undergoing EP procedures under Propofol. RESULTS: A significant prolongation of Tp-e under Propofol infusion (79.7±17.3 vs. 86.4±22.5ms, p<0.001) and of QTcFri (429.3±35.8 vs. 435.5±36.5, p=0.033) was detected. No significant change of the QTcB interval, JTc interval or QRS duration was observed. One case (0.09%) of ventricular fibrillation during rapid ventricular pacing under Propofol occurred. CONCLUSION: Although transmural dispersion of ventricular repolarisation is increased under Propofol, incidence of malignant ventricular arrhythmias is low. For evaluation of QT interval under Propofol, Fridericia's correction formula should be used rather than Bazett's formula.

Novel Use of GuideLiner with a Low-Profile Balloon for the Retrieval of Disrupted Balloon Catheter.

We report a case of successful percutaneous retrieval of an unexpectedly disrupted balloon catheter using GuideLiner and a low-profile balloon. The procedure and the mechanism of this novel technique were described in detail with ex-vivo testing. This case demonstrated the utility of the combination of GuideLiner and low-profile balloon as a bail-out for intravascular foreign body.

Atrial rhythm influences catheter tissue contact during radiofrequency catheter ablation of atrial fibrillation: comparison of contact force between sinus rhythm and atrial fibrillation.

Catheter tissue contact force (CF) is an important factor for durable lesion formation during radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). Since CF varies in the beating heart, atrial rhythm during RFCA may influence CF. A high-density map and RFCA points were obtained in 25 patients undergoing RFCA of AF using a CF-sensing catheter (Tacticath, St. Jude Medical). The operators were blinded to the CF information. Contact type was classified into three categories: constant, variable, and intermittent contact. Average CF and contact type were analyzed according to atrial rhythm (SR vs. AF) and anatomical location. A total of 1364 points (891 points during SR and 473 points during AF) were analyzed. Average CFs showed no significant difference between SR (17.2 ± 11.3 g) and AF (17.2 ± 13.3 g; p = 0.99). The distribution of points with an average CF of ≥20 and <10 g also showed no significant difference. However, the distribution of excessive CF (CF ≥40 g) was significantly higher during AF (7.4 %) in comparison with SR (4.2 %; p < 0.05). At the anterior area of the right inferior pulmonary vein (RIPV), the average CF during AF was significantly higher than during SR (p < 0.05). Constant contact was significantly higher during AF (32.2 %) when compared to SR (9.9 %; p < 0.01). Although the average CF was not different between atrial rhythms, constant contact was more often achievable during AF than it was during SR. However, excessive CF also seems to occur more frequently during AF especially at the anterior part of RIPV.

Evaluation of potential underuse of cardiac resynchronization therapy for heart failure with reduced ejection fraction.

BACKGROUND: The number of patients with chronic heart failure is increasing in Japan. However, the annual number of patients with heart failure who receive cardiac resynchronization therapy (CRT) has been constant in the last few years. In this study, we evaluated patients who did not receive CRT despite being eligible for this treatment to elucidate the clinical impact of CRT administration. METHODS: We assessed 214 patients with a left ventricular ejection fraction (LVEF) ≤ 50% (excluding patients treated with CRT) who underwent transthoracic echocardiography between January and May 2020 at our institution. The patients were stratified into two groups: Group A (n = 26; patients eligible for CRT) and Group B (n = 188; patients ineligible for CRT); however, all patients only received pharmacological therapy. We retrospectively analyzed the prognosis of these patients with respect to the cumulative number of hospitalizations for heart failure and cardiogenic deaths. RESULTS: We observed no significant between-group differences in age, sex, and severity/diagnosis of organic heart disease. Group A had a significantly higher number of hospitalizations for heart failure and cardiogenic deaths than Group B (log-rank test, P < .01; hazard ratio, 3.05; 95% confidence interval, 1.31-7.09; average follow-up period, 675 days). CONCLUSIONS: This study shows that 12% of patients were eligible for CRT. However, the implantation rate was low and no one was implanted. CRT is underutilized in patients who have heart failure with reduced LVEF. Therefore, we strongly recommend CRT for patients with indications for CRT.

Inter-observer differences in interpretation of coronary pressure-wire pullback data by non-expert interventional cardiologists.

The physiological pattern of coronary artery disease as determined by pressure-wire (PW)-pullback is important for decision-making of revascularization and risk stratification of patients. However, it remains unclear whether inter-observer differences in interpreting PW-pullback data are subject to the expertise of physicians. This study sought to investigate the subjectivity of this assessment among non-experts. Expert interventional cardiologists classified 545 PW-pullback traces into physiologically focal or physiologically diffuse disease pattern. Defining expert-consensus as the reference standard, we evaluated ten non-expert doctors' classification performance. Observers were stratified equally by two ways: (i) years of experience as interventional cardiologists (middle-level vs. junior-level) and (ii) volume of institutions where they belonged to (high-volume center vs. low-volume center). When judged against the expert-consensus, the agreement of non-expert observers in assessing physiological pattern of disease (focal or diffuse) ranged from 69.1 to 85.0% (p for heterogeneity < 0.0001). There was no evidence for a moderating effect of years of experience; the pooled accuracy of middle-level doctors was 78.8% (95% confidential interval [CI] 72.8-84.7%) vs. 79.1% for junior-level doctors (95% CI 75.9-82.2%, p = 0.95 for difference). On the other hand, we observed a significant moderating effect of center volume. Accuracy across non-experts in high-volume centers was 82.7% (95% CI 80.3-85.1%) vs. 75.1% for low-volume centers (95% CI 71.9-78.3%, p = 0.0002 for difference). Interpretation of PW-pullback by non-expert interventional cardiologists was considerably subjective.

Feasibility of kissing balloon technique through guide extension catheters: an experimental bench test.

Previous reports showed that GuideLiner (GL) and Guidezilla (GZ) can accommodate bulky and multiple devices beyond the official profiles. However, feasibility of kissing balloon technique (KBT) through these devices is unknown. The tested devices included 7Fr-GL/GZ and respective three types of 2.5 mm semi-compliant (SC) and non-compliant (NC) balloons: conventional model (CM), tapered-tip model (TM) and latest model (LM). First, three experienced operators attempted to advance all 21 combinations of the 2 balloons through GL/GZ on the guidewires and assessed the crossability in 3 grades: easy, difficult and impossible. Second, the only balloon combinations graded as easy by all operators were tested in the polyurethane-made bifurcation model which required KBT following cross-over stenting. Within the total of 42 device combinations, only one balloon combination of double LM-NC balloons was classified as easy in both GL/GZ by consensus opinion of the operators. While two combinations of LM-SC and LM-SC/NC balloons were classified as difficult in both GL/GZ, all four combinations of LM-SC/NC and CM/TM-NC balloons were classified as difficult only in GL. Other 32 combinations were all classified as impossible. In the bifurcation model, the combination of double LM-NC balloons using GL achieved KBT while the same balloon combination with GZ failed. The feasibility of KBT using child-catheter is highly dependent on the device characteristics. The combination of latest small-profile NC balloons through GL could be clinically applicable.

Interference Between Pressure-Wire and Deployed Coronary Stents: Insights from a Bench Test.

BACKGROUND: While several complications related to pressure-wire (PW) have been reported, mechanistic justification has not always been offered. Furthermore, interference between a PW and a protruding side-branch stent has not been previously reported. The purpose of this study was to evaluate interference between PW-pullback from a main-branch with a protruded ostial stent deployed in a side-branch. METHODS: In a polyurethane bifurcation vessel model, PW-pullback was performed in a main-branch following protruded ostial stenting in a side-branch. Tested PWs included PressureWire X, Comet, OptoWire, and Verrata. For each PW, pullback was performed through the same proximal cell of the protruded stent 20 times. Interference during PW-pullback was objectively analyzed with a fiberscope placed at the distal main-branch and classified into 3 grades according to the interaction with stent strut. RESULTS: There were significant differences in the rate of interference between the PWs. No-interference, interference without strut traction, and interference with strut traction (i.e. stent deformation) were observed as follows: 17/20, 3/20, and 0/20 in PressureWire X; 19/20, 1/20, and 0/20 in Comet; 8/20, 10/20, and 2/20 in OptoWire; and 13/20, 2/20, and 5/20 in Verrata, respectively (p for any differences: <0.001). Visually identifiable major stent deformation was observed once in OptoWire due to the deep concave sensor window and twice in Verrata due to the proximal gap between the sensor and coiled-wire. CONCLUSIONS: PW-pullback in the main-branch after side-branch ostial stenting should be carefully performed to avoid stent deformation. Consideration on the specific mechanical features of the PW is also essential.

Physiological Pattern of Disease Assessed by Pressure-Wire Pullback Has an Influence on Fractional Flow Reserve/Instantaneous Wave-Free Ratio Discordance.

BACKGROUND: Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) disagree on the hemodynamic significance of a coronary lesion in ≈20% of cases. It is unknown whether the physiological pattern of disease is an influencing factor for this. This study assessed whether the physiological pattern of coronary artery disease influences discordance between FFR and iFR measurement. METHODS AND RESULTS: Three-hundred and sixty intermediate coronary lesions (345 patients; mean age, 64.4±10.3 years; 76% men) with combined FFR, iFR, and iFR pressure-wire pullback were included for analysis from an international multicenter registry. Cut points for hemodynamic significance were FFR ≤0.80 and iFR ≤0.89, respectively. Lesions were classified into FFR+/iFR+ (n=154; 42.7%), FFR-/iFR+ (n=38; 10.6%), FFR+/iFR- (n=41; 11.4%), and FFR-/iFR- (n=127; 35.3%) groups. The physiological pattern of disease was classified according to the iFR pullback recordings as predominantly physiologically focal (n=171; 47.5%) or predominantly physiologically diffuse (n=189; 52.5%). Median FFR and iFR were 0.80 (interquartile range, 0.75-0.85) and 0.89 (interquartile range, 0.86-0.92), respectively. FFR disagreed with iFR in 22% (79 of 360). The physiological pattern of disease was the only influencing factor relating to FFR/iFR discordance: predominantly physiologically focal was significantly associated with FFR+/iFR- (58.5% [24 of 41]), and predominantly physiologically diffuse was significantly associated with FFR-/iFR+ (81.6% [31 of 38]; P<0.001 for pattern of disease between FFR+/iFR- and FFR-/iFR+ groups). CONCLUSIONS: The physiological pattern of coronary artery disease was an important influencing factor for FFR/iFR discordance.

Prevalence of electrocardiographic abnormalities in young, elite Japanese athletes.

BACKGROUND: The question as to whether or not electrocardiogram (ECG) evaluations should be performed in all athletes is still controversial. So, in this study, the prevalence of electrocardiographic abnormalities was evaluated in young, elite Japanese athletes. METHODS: Subjects included 174 male and 101 female Japanese athletes (mean age, 21.5 years). Sports activities included baseball, basketball, diving, fencing, gymnastics, judo, rhythmic gymnastics, soccer, swimming, tennis, track and field, volleyball, and water polo. A 12-lead resting ECG was recorded and evaluated. We used the criteria for distinctly abnormal ECG patterns as defined by Pelliccia et al. Subjects were divided into 2 groups on the basis of their exercise training type: an endurance training group and a static training group. RESULTS: Twenty six of 174 male subjects (14.9%) and 11 of 101 (10.9%) female subjects presented with abnormal ECG results. ECG abnormalities were observed much more frequently in track athletes compared to athletes of other sporting events. Field players did not present with any ECG abnormalities. Overall, the incidences of ECG abnormalities were statistically lower in the static exercise training group than in the endurance training group both in male and female. High voltage of left ventricle was observed in 114 of 175 male subjects (65.1%), and 27 of 101 female subjects (26.7%). CONCLUSIONS: The prevalence of ECG abnormalities in young, elite, Japanese athletes was comparable to that previously reported by both Western and Asian investigators.

The Lewis Lead for Detection of Ventriculoatrial Conduction Type.

BACKGROUND: Identification of a possible ventriculoatrial (VA) dissociation in wide QRS complex tachycardias is one of the most reliable criteria for differentiation of tachycardia origin. The Lewis lead has been proposed for detection of atrial activity during ventricular tachycardias. HYPOTHESIS: A modified Lewis-lead-ECG will be superior to the standard-lead ECG for detection of ventriculoatrial conduction during ventricular tachycardia. METHODS: Forty-seven patients underwent electrophysiological study, stimulated with a fixed cycle length of 400 ms in the ventricle. During stimulation, a standard-lead ECG and a modified Lewis-lead ECG were recorded. Simultaneously, VA conduction was documented by intracardiac electrograms. Surface ECGs were presented to 6 blinded examiners for VA conduction assessment. RESULTS: Type of VA conduction was correctly diagnosed in significantly more ECGs in the Lewis-lead ECG group (mean, 35.0 [75%]) than in the standard-lead ECG group (mean, 29.2 [62%]; P = 0.045). Ventriculoatrial dissociation also was significantly more often correctly diagnosed in the Lewis-lead ECG group (mean, 17.7 [71%]) than in the standard-lead ECG group (mean, 12.7 [49%]; P = 0.014). Interobserver agreement was moderate in both groups (κ = 0.45 and κ = 0.49, respectively). CONCLUSIONS: Compared with standard-lead ECG, modified Lewis-lead ECG is associated with significantly improved detection of VA conduction type during fast ventricular pacing and thus may help improve ECG diagnosis.

Comparison of the anterior and posterior mitral isthmus ablation lines in patients with perimitral annulus flutter or persistent atrial fibrillation.

BACKGROUND: Catheter ablation of left atrial linear lesions is an effective treatment option for perimitral flutter and is often used as a substrate modification approach for persistent atrial fibrillation. The two most popular mitral isthmus lines are those of the anterior or the posterior mitral isthmus. A comparison of these two mitral isthmus ablation approaches is still pending. METHODS: Patients undergoing catheter ablation either at the anterior or the posterior mitral isthmus were included. Procedural success, conduction block, procedure durations, complications, and the necessity of a coronary sinus ablation were analyzed. RESULTS: We investigated 80 consecutive patients, 40 (50%) with an anterior and 40 (50%) with a posterior mitral isthmus line. Twenty (25.0%) patients had perimitral annulus flutter; the remainder of the patients had persistent atrial fibrillation. Bidirectional conduction block was achieved in the same proportion in the anterior group (36; 90.0%) as it was in the posterior group (30; 75.0%) (statistically insignificant). Duration of procedure (18 ± 12 vs. 34 ± 24 min, p = 0.001), radiofrequency application (11 ± 7 vs. 18 ± 11 min, p = 0.004), and fluoroscopy (2 ± 2 vs. 8 ± 8 min, p < 0.001) values were all significantly lower in the anterior group. Only patients in the posterior line group had to be ablated via the coronary sinus 24 (60.0 %). CONCLUSIONS: Ablation at the anterior mitral isthmus shows the same success rate as the posterior mitral isthmus does. Catheter ablation at the anterior mitral isthmus is associated with significantly shorter procedure durations without the need of a coronary sinus ablation.

Left ventricular rupture associated with Takotsubo cardiomyopathy.

A 70-year-old woman was admitted to the hospital with chest discomfort after quarreling with her neighbors. Electrocardiography revealed ST-segment elevation in leads I, II, III, aVL, aVF, and V2 through V6. Coronary angiography demonstrated normal arteries, but left ventriculography showed apical akinesis and basal hyperkinesis. Takotsubo cardiomyopathy was diagnosed on the basis of these characteristic findings. The creatine kinase and creatine kinase-MB concentrations were elevated at admission and reached maximum levels 6 hours after admission. The plasma level of brain natriuretic peptide was 10.7 pg/mL (reference range, <18.4 pg/mL) on the first hospital day. ST-segment elevation in leads I, II, III, aVL, aVF, and V2 through V6 persisted at 72 hours after admission. On the third hospital day, sudden rupture of the left ventricle occurred, and despite extensive resuscitation efforts, the patient died. Takotsubo cardiomyopathy presents in a manner similar to that of acute myocardial infarction, but ventricular systolic function usually returns to normal within a few weeks. To our knowledge, this is the first reported case of fatal left ventricular rupture associated with takotsubo cardiomyopathy. We suggest that takotsubo cardiomyopathy may be a newly recognized cause of sudden cardiac death.

Discrimination of Brugada syndrome patients from individuals with the saddle-back type ST-segment elevation using a marker of the standard 12-lead electrocardiography.

BACKGROUND: In the clinical situation, the saddle-back (S-B) type is more frequently detected than the coved type. In the present study, the discrimination of Brugada syndrome from the S-B type individuals using a marker of the standard 12-lead electrocardiography (ECG) was attempted. METHODS AND RESULTS: The study group consisted of 55 individuals with the S-B type in whom pilsicainide provocation test (PLC test) was carried out. The time from the onset of the QRS wave in lead V(2) (IV (2)) to the peak of the late R-like wave in the QRS wave (PV(2)), and the time from IV(2) to the offset of the QRS wave in lead V(5) (EV(5)) were measured. The coved type was induced by the PLC test in 29 cases (N-C group), but not in the remaining 26 cases (N-N group). The (IV(2) -PV(2)) - (IV(2) - EV(5)) value before the PLS test was greater in the N-C group than in the N-N group. The negative predictive value of ;(IV(2) - PV(2)) - (IV(2) - EV(5)) > or =0' was 76.4% for the prediction of a positive PLC test. CONCLUSIONS: A ;(IV(2) - PV(2)) - (IV(2) - EV(5)) > or =0' is a useful ECG marker for the discrimination of Brugada syndrome in the S-B type individuals.

Long-term follow-up of a patient with Kawasaki disease and coronary aneurysm associated with asymptomatic thrombosis: a case report.

A 20-year-old male was first diagnosed with Kawasaki disease at age 2 years 9 months. Coronary angiography in the acute phase revealed coronary aneurysms, so chronic antiplatelet therapy was initiated with aspirin and ticlopidine. The patient was asymptomatic and was followed up. Stress myocardial imaging showed asymptomatic myocardial ischemia at age 20 years. Coronary angiography was performed, and revealed 99% occlusion of the right coronary artery and collateral circulation from the left coronary artery. Occlusion was attributed to coronary aneurysm thrombosis. Much remains unknown about the long-term prognosis in patients with coronary aneurysm associated with Kawasaki disease. Asymptomatic children who are followed up sometimes develop ischemic heart disease as young adults. This case highlights the need for long-term follow-up in patients with Kawasaki disease and coronary aneurysms.