A case report of lead dysfunction presenting as high ventricular premature complex burden.

Pacemaker-troubleshooting is an important step in the evaluation of a patient with syncope post-pacemaker-implantation. The basic functions of sensing, pacing and impedance may remain spuriously normal in the case of lead-microfracture or insulation break. We report a case in which the lead dysfunction was diagnosed based on multiple episodes of premature ventricular beats.

ECG in an Athlete With Syncope: Innocuous Incomplete Right Bundle Branch Block or Brugada Pattern?

Abnormalities of an athlete's electrocardiogram may be the result of an underlying heart disease and may carry a risk of sudden death. It is important that electrocardiographic abnormalities are correctly distinguished. We present the case of a young marathon athlete presenting with syncope and incomplete right bundle block pattern suggestive of a type 2 Brugada pattern. (Level of Difficulty: Advanced.).

Loss of left ventricular component of biventricular pacing with low atrial rhythm, what is the mechanism?

Effective biventricular pacing is important to improve survival in patients with heart failure. We report a case of a patient with heart failure, who underwent cardiac resynchronization therapy, who had loss of biventricular pacing when in low atrial rhythm. We discuss the probable mechanism for the same.

Atrial tachycardia misinterpreted as ventricular high-rate event in a patient with the sick sinus disease and a DDD pacemaker.

The device misinterpreted atrial high-rate episode (AHRE) as ventricular high-rate episode (VHRE), since consecutive atrial beats fell in the postventricular atrial blanking (PVAB) period. This resulted in the failure of auto mode switch (AMS). This was corrected by decreasing the PVAB and the patient was asymptomatic on follow-up.

Egg-shell calcification in Pick's disease (chronic constrictive pericarditis).

Egg-shell calcification is rare in cases with constrictive pericarditis. It leads to significant right heart failure and the only treatment is surgical excision of the pericardium. We present a case of a 22-year-old-male who was diagnosed to have severe pericardial calcification on the chest X-ray, which eventually led to a diagnosis of constrictive pericarditis and required an early surgical correction. This case shows that a common diagnostic test such as a chest X-ray does help to diagnose a severe systemic condition.

Successful use of venovenous snare to fix the wire in a collateral vein for proper placement of the left ventricular lead during cardiac resynchronization therapy: a case report.

BACKGROUND: In cardiac resynchronization therapy, left ventricular (LV) lead placement at the desired position may be difficult due to abnormal coronary sinus (CS) and lateral vein anatomy. We present a case with difficult anatomy in which we used 'an indigenous snare' made from hardware used for coronary angioplasty procedures, which is available in any cardiac catheterization laboratory. CASE SUMMARY: A 52-year-old man presented with dyspnoea due to chronic heart failure was evaluated for cardiac resynchronization therapy. The LV lead was difficult to advance into the only target lateral branch of the CS due to a combination of angulation and proximal stenosis. Balloon dilation was tried first, but we failed to track the LV lead. We formed a venovenous loop, advancing the coronary guidewire 0.014″ into the posterolateral vein; subsequently into the middle cardiac vein via a collateral. The wire was advanced into the CS and then to superior vena cava. The guidewire then snared through the same left subclavian vein and exteriorized by using indigenous snare. Over this loop, the LV lead of the cardiac resynchronization therapy with defibrillator device was implanted successfully. DISCUSSION: We have used the snare technique, with the use of a snare prepared from a coronary guidewire. Use of such an indigenous snare has not been described before in the literature. The hardware used in this case is routinely used for coronary angioplasty procedures in all catheterization labs. The importance of our case is that no special hardware like dedicated snare was required to negotiate the LV lead at its desired location.

Changing QRS duration and morphology with A-paced and A-sensed rhythm in postcardiac resynchronization therapy (CRT) patients.

Meticulous interpretation of the ECGs of patients with cardiac resynchronization defibrillator therapy (CRT-D) device is important to ensure optimal synchronization of both the chambers. We present the ECGs of such a patient who was noted to have different morphologies of the biventricular-paced QRS depending in atrial-sensed (A-sensed) or atrial-paced (A-paced) rhythm.

Takotsubo Cardiomyopathy Masquerading as Acute Coronary Syndrome.

Takotsubo cardiomyopathy, also called transient left ventricular apical ballooning syndrome or Gebrochenes-Herz-Syndrome, is a rare entity which may masquerade as acute coronary syndrome (ACS) with sudden onset of chest pain and/or dyspnea, transient left ventricle apical akinesia, electrocardiographic changes typical of ACS and mild increase in cardiac enzymes in the background of normal coronary arteries. Here, we present a case of a 45 year old female who presented with acute onset dyspnea and chest pain with severe ischemic changes on the ECG and raised troponin levels. She was treated with a provisional diagnosis of an ACS but on further workup was found to have Takotsubo cardiomyopathy. Her presentation to the hospital along with relevant clinical findings, electrocardiographic, echocardiographic and angiographic findings are presented in the article.

Phenotype guided characterization and molecular analysis of Indian patients with long QT syndromes.

BACKGROUND: Long QT syndromes (LQTS) are characterized by prolonged QTc interval on electrocardiogram (ECG) and manifest with syncope, seizures or sudden cardiac death. Long QT 1-3 constitute about 75% of all inherited LQTS. We classified a cohort of Indian patients for the common LQTS based on T wave morphology and triggering factors to prioritize the gene to be tested. We sought to identify the causative mutations and mutation spectrum, perform genotype-phenotype correlation and screen family members. METHODS: Thirty patients who fulfilled the criteria were enrolled. The most probable candidate gene among KCNQ1, KCNH2 and SCN5A were sequenced. RESULTS: Of the 30 patients, 22 were classified at LQT1, two as LQT2 and six as LQT3. Mutations in KCNQ1 were identified in 17 (77%) of 22 LQT1 patients, KCNH2 mutation in one of two LQT2 and SCN5A mutations in two of six LQT3 patients. We correlated the presence of the specific ECG morphology in all mutation positive cases. Eight mutations in KCNQ1 and one in SCN5A were novel and predicted to be pathogenic by in-silico analysis. Of all parents with heterozygous mutations, 24 (92%) of 26 were asymptomatic. Ten available siblings of nine probands were screened and three were homozygous and symptomatic, five heterozygous and asymptomatic. CONCLUSIONS: This study in a cohort of Asian Indian patients highlights the mutation spectrum of common Long QT syndromes. The clinical utility for prevention of unexplained sudden cardiac deaths is an important sequel to identification of the mutation in at-risk family members.

The impact of age on the electroanatomical characteristics and outcome of catheter ablation in patients with atrial fibrillation.

BACKGROUND: Previous studies have indicated that atrial fibrillation (AF) in patients over the age of 60 at diagnosis is a risk factor for a substantial increase in cardiovascular events. However, information about the impact of age on the atrial substrate and clinical outcome after catheter ablation of AF is limited. METHODS: This study included 350 patients (53 ± 12 years, 254 males) who underwent circumferential pulmonary vein isolation (CPVI) of AF, guided by a NavX mapping system. The subjects were divided into three groups according to their age, as follows: Group I: age ≤50 (n = 141), Group II: age = 51-64 (n = 149) and Group III: age ≥65 years old (n = 60). The mean voltage and total activation time of the individual atria were obtained by using a NavX mapping system before ablation. Several parameters, including the gender, AF duration, and left atrial (LA) diameter were analyzed. RESULTS: The younger age group had a significantly smaller LA diameter (Group I vs Group II vs Group III, 36.89 ± 7.11 vs 39.16 ± 5.65 vs 40.77 ± 4.95 mm, P = 0.002) and higher LA bipolar voltage (2.09 ± 0.83 vs 1.73 ± 0.73 vs 1.86 ± 0.67 mV, respectively, P = 0.024), compared with the older AF patients. The LA bipolar voltage exhibited a significant reduction when the patients became older, however, that did not occur in the right atrium. The incidence of an AF recurrence was higher in the older age group than in the younger age groups. A subgroup of patients with lone AF was analyzed and age was found to be an independent predictor of the AF recurrence after receiving the first CPVI in the multivariable model (P < 0.05). CONCLUSIONS: Age has a significant impact on the LA substrate properties and outcome of the catheter ablation of AF.

Prognostic implications of the high-sensitive C-reactive protein in the catheter ablation of atrial fibrillation.

Previous studies have reported that increased high-sensitive C-reactive protein (hs-CRP) levels are associated with an inflammatory state. This study investigated the association among hs-CRP, substrate properties, and long-term clinical outcomes after catheter ablation of atrial fibrillation (AF). A total of 137 patients with AF (54 +/- 13 years) who underwent mapping and catheter ablation were included. The hs-CRP was measured before the first ablation procedure. The substrate properties (initiating triggers, biatrial mean voltage, and high-frequency sites) of the 2 atria and long-term outcome were investigated in patients in the low hs-CRP group (<75%, 2.92 mg/L) and high hs-CRP group (>75%, 2.92 mg/L). Patients with a higher hs-CRP were associated with an increased number of identified nonpulmonary vein ectopies (34.4% vs 17%, p = 0.034), lower mean left atrial (LA) voltage (1.72 +/- 0.73 vs 1.92 +/- 0.72 Hz, p = 0.045), and higher-frequency sites in the left atrium (71% vs 37%, p = 0.027). After a median follow-up period of 15 months, the single-procedure success rate (72% vs 53%, p = 0.008) and final success rate after multiple procedures (94% vs 81%, p = 0.02) were higher in the low hs-CRP group. In a multivariable regression model adjusted for other potential covariates, hs-CRP level (p = 0.021) and LA diameter (p = 0.032) were independent predictors of recurrence. In conclusion, baseline CRP levels before the first AF ablation procedure had an independent prognostic value in predicting long-term recurrence. Patients with a high hs-CRP level were associated with an abnormal LA substrate and high incidence of nonpulmonary vein AF sources.

The optimal automatic algorithm for the mapping of complex fractionated atrial electrograms in patients with atrial fibrillation.

CFAEs and the Voltage. Introduction: Catheter ablation of atrial fibrillation (AF) can be guided by the identification of complex fractionated atrial electrograms (CFAEs). We aimed to study the prediction of the CFAEs defined by an automatic algorithm in different atrial substrates (high voltage areas vs low voltage areas). Methods and Results: This study included 13 patients (age = 56 +/- 12 years, paroxysmal AF = 8 and persistent AF = 5), who underwent mapping and catheter ablation of AF with a NavX system. High-density voltage mapping of the left atrium (LA) was performed during sinus rhythm (SR) (248 +/- 75 sites per patient) followed by that during AF (88 +/- 24 sites per patient). The CFAE maps were based on the automatic-detection algorithm. "Operator-determined CFAEs" were defined according to Nademannee's criteria. A low-voltage zone (LVZ) was defined as a bipolar voltage of less than 0.5 mV during SR. Among a total of 1150 mapping sites, 459 (40%) were categorized as "operator-determined CFAE sites," whereas 691 (60%) were categorized as "operator-determined non-CFAE sites." The sensitivity and negative predictive value increased as the fractionated interval (FI) value of the automatic algorithm increased, but the specificity and positive predictive value decreased. The automatic CFAE algorithm exhibited the highest combined sensitivity and specificity with an FI of <60 ms for the sites inside the LVZ and FI < 70 ms for the sites outside the LVZ, when compared with a single threshold for both the high- and low-voltage groups combined (i.e., no regard for voltage) (ROC: 0.89 vs 0.86). Conclusions: The clinical relevance of the CFAE map would be improved if the calculated index values were accordingly scaled by the electrogram peak-to-peak amplitude.

The disparities in the electrogram voltage measurement during atrial fibrillation and sinus rhythm.

INTRODUCTION: The peak electrogram voltage is a typical metric applied at each site for voltage mapping. However, the peak amplitude depends on the direction and complexity of the wavefront propagation. The root-mean-square (RMS) measure of the amplitude is a temporal integral that represents the steady-state value. The objective of this study was to investigate the disparities between the electrogram voltage during SR and AF by using 2 recording modalities: the conventional peak voltage and an RMS measurement. METHODS AND RESULTS: This study enrolled 20 patients (age = 59 +/- 13) with paroxysmal AF undergoing catheter ablation guided by Ensite array. The unipolar electrogram voltage during SR and AF (7 seconds in duration) was obtained from the same sites, and labeled by the 3-dimensional (3D) geometry. Overall 1,200 electrograms were analyzed from equally distributed mapping sites in the left atrium. A point-by-point comparison of the unipolar peak negative voltage (PNV) showed less agreement (Bland and Altman test: 10.4% outside 2 standard deviations, and intraclass correlation coefficient [ICC]= 0.64). The RMS voltage demonstrated agreement between SR and AF for all sites (BA test: 5.9% of the sites, and the ICC = 0.81). The probability of predicting a low-voltage during AF using the voltage during SR was significantly lower when using the PNV measurement compared to that when using the RMS voltage (15% vs 61%, P < 0.05). CONCLUSION: The peak electrogram unipolar voltage during AF did not represent the voltage during SR. The RMS amplitude may be an alternative metric for voltage mapping to characterize the myocardial substrate.

Spatiotemporal organization of the left atrial substrate after circumferential pulmonary vein isolation of atrial fibrillation.

BACKGROUND: There is a paucity of data regarding the mechanism of maintaining atrial fibrillation (AF) after pulmonary vein isolation (PVI) in patients with AF. The aim of this study was to examine the impact of circumferential PVI on the left atrial (LA) substrate characteristics. METHODS AND RESULTS: Seventy-two AF patients (age, 53+/-11 years) underwent mapping and catheter ablation using an NavX system. The biatrial characteristics such as the complex fractionated atrial electrograms (CFEs; based on fractionated intervals) and frequency analysis (based on dominant frequencies) were mapped before and after PVI. PVI with electric isolation was performed in all patients. In the 45 patients who did not respond to PVI, the continuous CFEs (>8 seconds, 18+/-18% and 12+/-17% of the LA sites, before and after PVI, respectively, P=0.02), degree of LA fractionation (mean fractionated interval: 75.6+/-14.3 msec versus 87.3+/-16.7 msec, P=0.001), and mean LA dominant frequencies (6.92+/-0.88 Hz versus 6.58+/-0.91 Hz, P=0.001) decreased after PVI. Complete PVI altered the distribution of the CFEs toward the LA anteroseptum, mitral annulus, and LA appendage regions. A persistent presence of continuous CFEs in the vicinity of the dominant frequencies sites (observed in 53% patients) correlated with a higher procedural AF termination rate for the CFE ablation (63% versus 23%, P<0.05). CONCLUSIONS: Complete PVI eliminated some CFEs in the LA and altered the distribution of the CFEs. The persistent presence of CFEs before and after PVI in the vicinity of the high frequency sites is important for AF maintenance after PVI.

The impact of left atrial size on long-term outcome of catheter ablation of chronic atrial fibrillation.

BACKGROUND: The left atrial (LA) size is an important predictor of atrial fibrillation (AF) procedural termination and the long-term outcome. We sought to evaluate the long-term outcome in regard to the LA size and procedural termination. METHODS: Eighty-seven consecutive chronic AF patients (72 males, 53 +/- 10 years) underwent 3D mapping (NavX) and ablation. A stepwise approach including circumferential pulmonary vein (PV) isolation, linear ablation, and continuous complex-fractionated electrogram (CFE) ablation (targeting fractionation intervals of < 50 ms). Electrical cardioversion was applied to those without any procedural termination. The freedom from AF was defined as the maintenance of sinus rhythm without the use of any class I or III antiarrhythmic drugs after the blanking period. RESULTS: Among the 87 patients, all received a circumferential PV isolation, 93% a linear ablation, and 59% a continuous CFE ablation. Those with AF procedural termination (n = 30) had a better long-term outcome when compared with those without termination during a follow-up of 21 +/- 12 months. Moreover, a Kaplan-Meier analysis showed that in those with an LA diameter of less than 45 mm (n = 49), the freedom from AF rate was higher when procedural termination was achieved (P = 0.004). On the contrary, the outcome was comparable in those with an LA diameter of >or= 45 mm (n = 38), whether AF procedural termination occurred or not (P = 0.658). CONCLUSIONS: AF procedural termination was related to the long-term success during chronic AF ablation, especially in those with an LA diameter of less than 45 mm. The favorable effect of termination decreased when the LA diameter was >or= 45 mm.