Francis E. Marchlinski

Ventricular Tachycardia Storm After Initiation of Biventricular Pacing: Incidence, Clinical Characteristics, Management, and Outcome

Introduction: Cardiac resynchronization therapy (CRT) or biventricular pacing (BVP) is becoming an important treatment option in patients with severe congestive heart failure (CHF) and electrical dyssynchrony. When combined with implantable cardioverter‐defibrillator (ICD) therapy, cardiac resynchronization therapy with a defibrillator (CRT‐D) has been shown to improve quality of life, functional class, and, most recently, survival. However, left ventricular (LV) stimulation in the form of BVP in patients at high risk of developing ventricular tachyarrhythmias has raised concerns that BVP may be proarrhythmic. We describe the incidence, clinical characteristics, and management in a series of patients who developed ventricular tachycardia storm (VTS) after initiation of BVP.

Utility of Intracardiac Echocardiography in Left Heart Ablation for Tachyarrhythmias

Catheter‐based radiofrequency ablation in the left heart can provide effective therapy for tachyarrhythmias. The recent development of the real time intracardiac echocardiography (ICE) with 2D and Doppler color flow imaging can facilitate left heart ablation procedures. This report reviews the use of ICE during radiofrequency catheter ablation procedures for atrial fibrillation (AF) and ventricular tachycardia and is based on our own experience in 955 patients. ICE has a critical role for guiding transseptal catheterization, assisting placement of mapping/ablation catheters and monitoring lesion morphologic changes, especially in the pulmonary vein ostia, Marshall ligament region, thickened interatrial septum, left atrial posterior wall contiguous to esophagus, aortic valve cusps, and the epicardial regions. One of the more powerful utilities of ICE lies in its ability to identify and potentially reduce procedural complications including damage to intracardiac structures, residual atrial septal defect, left atrial thrombus formation, pulmonary vein stenosis, esophageal injury, myocardial air‐embolizaion and pericardial effusion during left heart ablation.

Changes in local wall thickness correlate with pathologic lesion size following radiofrequency catheter ablation: an intracardiac echocardiographic imaging study.

Introduction: High‐resolution intracardiac echocardiographic (ICE) imaging can accurately assess wall thickness during radiofrequency (RF) catheter ablation procedures. This study investigated the correlation of changes in wall thickness at the ablation site with pathologic lesion size. Methods and Results: ICE image‐guided 31 RF applications (30–50 W, up to 120 sec) were performed in five anesthetized closed chest swine (n = 5, body weight 35–60 kg). Twenty‐four lesions were delivered in the right and left atria with standard RF; seven lesions were delivered in the left ventricle (LV) with irrigated (30–40 ml/min) RF. Wall thickness and tissue echo density measured by ICE imaging (preand 1‐minute post‐RF delivery) with increased focal echo density following RF deployment in the atria (4.5 ± 1.5 vs 2.3 ± 1.0 mm pre‐RF) and the LV (9.8 ± 2.3 vs 6.8 ± 2.2 mm pre‐RF; P < 0.01). The observed changes in wall thickness (ΔWT) following ablation in the LV were greater than in the atria (3.0 ± 1.4 vs 2.2 ± 1.2 mm; P < 0.05). A significant correlation between ΔWT and lesion depth (ventricular: r = 0.85, P < 0.05; atrial: r = 0.82, P < 0.01) was demonstrated at all ablation sites. Local wall thickness measured post‐RF also significantly correlated with lesion depth (r = 0.89, P < 0.01), especially with that of transmural lesions (r = 0.95, n = 23, P < 0.001) at atrial and LV sites. Conclusion: Therapeutic RF ablation results in mural swelling and increased echo density. These changes can be detected by ICE imaging and correlate with pathologic lesion size. ICE imaging may be useful in online quantification of lesion size, especially for transmural lesions during clinical catheter ablation procedures.

Use of Noncontact Mapping and Saline-Cooled Ablation Catheter for Sinus Node Modification in Medically Refractory Inappropriate Sinus Tachycardia

Background: Inappropriate sinus tachycardia (IST) is characterized by heart rate (HR) increase out of proportion to stress level. Radiofrequency (RF) modification of the sinus node (SN) is an accepted treatment modality for medically refractory IST. We describe a new technique using noncontact mapping and a saline irrigated catheter for SN modification.

Insights into the Electrophysiology of Ventricular Tachycardia Gained by the Catheter Ablation Experience:.: "Learning While Burning"

VT Catheter Ablation. The success of catheter ablation has significantly improved the treatment of patients with cardiac arrhythmias and has established electrophysiology as an increasingly interventional subspecialty. Some members of the electrophysiology community have expressed concern that this success has been purchased at the cost of undermining what had been our primary concern: understanding the anatomic and physiologic basis of arrhythmia syndromes. In many laboratories, endpoints such as case load and primary success have eclipsed physiologic investigation. Despite these trends, however, catheter ablation is not inherently at odds with investigation and education. On the contrary, because the lesions delivered with current techniques are much more discrete than the effects of antiarrhythmic agents or surgical ablation, catheter ablation can be used as a research tool directed toward a more precise understanding of arrhythmia substrates. Conscious attempts at “learning while burning” have already provided important and unique information about arrhythmia pathogenesis.

Comparison of high power, medium power, and irrigated-tip ablation strategies for pulmonary vein isolation in a canine model.

Background: We sought to compare the efficacy and collateral damage during pulmonary vein (PV) isolation in a canine model using three different ablation strategies.

Use of Multisite Electroanatomic Mapping to Facilitate Ablation of Intra‐Atrial Reentry Following the Mustard Procedure

Multisite Electroanatomic Mapping. Ablation of intra‐atrial reentrant tachycardia following Mustard or Senning procedures has low success rates. The Biosense Carto system was used to map intra‐atrial reentry in a 22‐year‐old woman who had undergone a Mustard procedure. A line of block was created connecting a Mustard baffle suture line to the tricuspid valve annulus, which terminated the arrhythmia and prevented its reinitiation. Multisite electoanatomic mapping was invaluable in defining atrial anatomy and the intra‐atrial reentrant pathway, and in creating a contiguous line of block. This mapping may improve ablation success rates in patients following the Mustard or Senning repair.

Longer Paced QRS Duration is Associated With Increased Prevalence of Right Ventricular Pacing-Induced Cardiomyopathy

Pacing‐induced cardiomyopathy (PICM) is an important cause of heart failure in patients exposed to frequent right ventricular (RV) pacing. While echocardiography is diagnostic, the optimal surveillance strategy remains unknown. We sought to identify clinical and electrocardiographic factors associated with the presence of PICM to guide further testing.

ECG clues for diagnosing ventricular tachycardia mechanism.

Three mechanisms underlie the initiation and maintenance of ventricular tachycardia: automaticity, triggered activity, and reentry. As straightforward as these mechanisms are, assessing which mechanism is operative in a particular patients ventricular tachycardia can be difficult. The optimal treatment strategy for ventricular tachycardia in a given patient can be influenced by the mechanism underlying the ventricular tachycardia. Appropriately counseling patients, choosing the optimal pharmacologic agent that maximizes efficacy while minimizing undesirable side effects, risks, and toxicities, as well as recommending and timing ablative therapy all hinge on identifying the probable mechanism of ventricular tachycardia. Much has been published regarding invasive electrophysiologic maneuvers that allow for correct diagnosis of ventricular tachycardia mechanism. The aim of this clinical review is to provide insight into VT mechanisms based on ECG clues of spontaneous arrhythmia events and the response to pharmacologic manipulation prior to invasive electrophysiologic evaluation.

Screening for Cardiac Magnetic Resonance Scar Features by 12-Lead ECG, in Patients with Preserved Ejection Fraction

Increased QRS score and wide spatial QRS‐T angle are independent predictors of cardiovascular mortality in the general population. Our main objective was to assess whether a QRS score ≥5 and/or QRS‐T angle ≥105° enable screening of patients for myocardial scar features.