A hazardous collateral pathway following asymptomatic lead-related venous occlusion?

Routine venography should be performed before the device upgrade. Clinicians should not be unconcerned because of the lack of symptoms following lead-related venous occlusion. Knowledge of collateral anatomy is essential for future interventional plans.

Differences in Electrical Delay Between the Mid-septum and Apex with the Right Ventricular Lead: Novel Implications for Pacemaker Sensing.

Ventricular sensing relies on the analysis of a local intracardiac electrogram in reference to the QRS on the surface electrocardiogram. If both signals do not coincide in time, there is a delay in sensing intrinsic ventricular activity. We evaluated possible differences in the electrical delay between the mid-septum and apex as determined by the right ventricular (RV) lead position using a pacing system analyzer (PSA) during conventional pacemaker implantation.

Right ventricular lead sensing latency in pacemaker therapy.

Background: Pacemaker implantation involves intraoperative testing of ventricular sensing using a device called a pacing system analyzer (PSA). The value obtained is expected to correspond to those taken by the pacemaker after its implantation. This study determined the latency period for sensing intracardiac electrogram (EGM) by the right ventricular (RV) lead.

Unexpected inhibition of bradycardia pacing due to oversensing in ICD lead fracture associated with spurious tachyarrhythmia detection and discharges.

Ιn a 76-year old man with a dual-chamber ICD implanted five years ago, dizzy spells and significant bradycardia on Holter were not initially recognized as inhibition of bradycardia pacing, due to oversensing. Hospital admission was deemed necessary only after repetitive ICD shocks attributed to right ventricular pace-sense lead fracture. The need to ensure adequate ICD antibradycardia backup pacing in pacing-dependent patients when deleterious sensing errors occur, cannot be overemphasized.

Effects of transcutaneous cardiac pacing on ventricular repolarization and comparison with transvenous pacing.

Background: The electrocardiographic (ECG) effects of transcutaneous cardiac pacing (TCP) on ventricular repolarization have not been studied in detail. This study evaluated the influence of TCP on ventricular repolarization. The results were compared with those obtained by conventional transvenous right ventricular pacing (TVP).

The electrocardiogram of ventricular capture during transcutaneous cardiac pacing.

Background: Transcutaneous cardiac pacing (TCP) is deeply entwined with the problem of assessing ventricular capture on the electrocardiogram (ECG). We sought clarification of ventricular capture during TCP.

Methods: We studied one hundred and ten patients (75 ± 12 years) with bradycardia who underwent pacemaker or implantable cardioverter-defibrillator implantation.

QRS fragmentation and T-wave inversion as factors of vulnerability to recurrent ventricular tachycardia.

Clinical manifestation of late onset recurrent monomorphic ventricular tachycardia (VT) in patients with normal left ventricular ejection fraction may elude diagnosis despite elaborate testing. This report describes a 67-year-old woman with structurally normal heart who presented with recurrent VT in the absence of predisposing factors. Repeated extensive diagnostic testing, including magnetic resonance imaging and coronary angiography, did not disclose any abnormality.

Effect of heart rate and pacing mode on QRS fragmentation.

Background: The study was designed to investigate the effect of heart rate and pacing mode on QRS fragmentation (f-QRS). Moreover, the usefulness of f-QRS in distinguishing patients with impaired left ventricular ejection function (EF) and ventricular tachycardia (VT) from patients with normal EF was assessed.

Methods: Three hundred and six recipients, with dual-chamber device, with intrinsic narrow or wide QRS complex and preserved atrioventricular conduction were grouped into normal-EF or impaired-EF VT.

Impact of QT interval prolongation following antiarrhythmic drug therapy on left ventricular function.

Aim: We assessed whether antiarrhythmic drug-induced QT interval prolongation affects left ventricular function.

Methods: Study population included 54 patients with symptomatic recent onset atrial fibrillation spontaneously cardioverted to sinus rhythm. Electrocardiographic and echocardiographic studies were done before initiating and after achieving drug's steady state.

Effect of heart rate on the intrinsic and the ventricular-paced QRS duration.

Background: We evaluated the effect of heart rate on the intrinsic and the ventricular-paced QRS duration in implanted device recipients with normal or reduced left ventricular ejection fraction (EF).

Methods: We studied 239 outpatients with preserved intrinsic ventricular activation and normal (n=92) or reduced (n=147) EF who had apical (RVA) or mid-septal (RVS) right ventricular lead position. The QRS duration was measured at baseline and during atrial-based pacing at increased heart rate to ensure intrinsic or ventricular-paced QRS activation.

Facilitating assessment of QT interval duration during ventricular pacing.

Aims: We aimed to facilitate the assessment of the QT interval duration during conventional right ventricular pacing (VP) by uncovering relationships with the underlying QT interval during intrinsic atrioventricular conduction (IC).

Methods And Results: The study patients (n = 122, age 68 ± 11 years) were dual-chamber device recipients with preserved IC and narrow QRS complexes. Patients were classified into either 'normal-QT' (n = 70) or 'prolonged-QT' (n = 52) group.

Optimal QT/JT interval assessment in patients with complete bundle branch block.

Background: Prolonged ventricular repolarization duration confers increased risk for malignant ventricular arrhythmias. We sought to clarify the optimal method of QT/JT interval assessment in patients with complete bundle branch block (BBB).

Methods: Study patients (n = 71) were dual-chamber device recipients with baseline left or right BBB who preserved intrinsic ventricular activation during incremental atrial pacing.

Predictors of high on-treatment platelet reactivity early after clopidogrel loading in ST-elevation myocardial infarction.

Background: Given that platelet inhibition is crucial when ST-elevation myocardial infarction (STEMI) patients undergo primary PCI (PPCI), the identification of factors associated with early high on-treatment platelet reactivity may be important.

Methods And Results: Consecutive STEMI patients admitted for PPCI were considered for platelet reactivity assessment 2 h after loading with 600 mg clopidogrel using the VerifyNow point-of-care P2Y12 assay. A cut-off of ≥235 P2Y12 reaction units indicated high on-treatment platelet reactivity.

Predicting torsade de pointes in acquired long QT syndrome: optimal identification of critical QT interval prolongation.

Objectives: To determine the optimal method of ventricular repolarization assessment in predicting torsade de pointes (Tdp) in acquired long QT syndrome (LQTS) within the context of the recommended cutoff levels of concern for QT/corrected QT (QTc) interval prolongation.

Methods: Twenty-nine patients with LQTS and Tdp (age 66 ± 11 years) and matched controls were studied. Standard 12-lead electrocardiograms were utilized to evaluate ventricular repolarization by using six different QT/JT heart rate correction methods.

Long-term response of the left ventricle to cardiac resynchronization therapy: insights from standard and strain echocardiography.

Left ventricular (LV) response to cardiac resynchronization therapy (CRT) has typically been studied over 3- to 12-month periods. Longer-term data are unclear and response of strain parameters has not been reported. The authors evaluated long-term response with standard and strain echocardiography in 57 patients (52±15 years; 40 male; 30 white; 15 with ischemic etiology) who received a CRT-defibrillator between January 2004 and December 2005.

New diagnosis of arrhythmogenic right ventricular cardiomyopathy in an octogenarian with the help of Fontaine electrocardiographic leads.

We report an 85-year-old man with arrhythmogenic right ventricular cardiomyopathy who presented with monomorphic ventricular tachycardia. This is the oldest patient recorded with this disease. The presence of epsilon waves by the Fontaine lead system provided a high degree of suspicion for the disease.

Preferred QT correction formula for the assessment of drug-induced QT interval prolongation.

Introduction: There is debate on the optimal QT correction method to determine the degree of the drug-induced QT interval prolongation in relation to heart rate (DeltaQTc).

Methods: Forty-one patients (71 +/- 10 years) without significant heart disease who had baseline normal QT interval with narrow QRS complexes and had been implanted with dual-chamber pacemakers were subsequently started on antiarrhythmic drug therapy. The QTc formulas of Bazett, Fridericia, Framingham, Hodges, and Nomogram were applied to assess the effect of heart rate (baseline, atrial pacing at 60 beats/min, 80 beats/min, and 100 beats/min) on the derived DeltaQTc (QTc before and during antiarrhythmic therapy).

Mechanisms of nonfatal acute myocardial infarction late after stent implantation: the relative impact of disease progression, stent restenosis, and stent thrombosis.

Background: The impact of stent restenosis, stent thrombosis, or progression of disease at another site as responsible mechanisms of acute myocardial infarction (AMI) after stent implantation is not clear.

Methods: By searching our catheterization laboratory database for a 4-year period, 91 cases of nonfatal AMI at least 1 month after stent implantation (32.6% drug-eluting stents) were identified.

Heart rate-dependence of QTc intervals assessed by different correction methods in patients with normal or prolonged repolarization.

Background: There is a continuing debate about the optimal method for QT interval adjustment to heart rate changes. We evaluated the heart rate dependence of QTc intervals derived from five different QT correction methods.

Methods: Study patients (n = 123, age 68 +/- 11 years) were dual-chamber device recipients with baseline normal or prolonged QT interval who had preserved intrinsic ventricular activation with narrow QRS complexes.