Hugh T. McElderry

Ventricular Tachycardia Originating From the Posterior Papillary Muscle in the Left Ventricle A Distinct Clinical Syndrome

Background—Several distinct forms of focal ventricular tachycardia (VT) from the left ventricle (LV) have been described. We report a new syndrome of VT arising from the base of the posterior papillary muscle in the LV. Methods and Results—Among 290 consecutive patients who underwent ablation for VT or symptomatic premature ventricular complexes (PVCs) based on a focal mechanism, 7 patients were found to have an ablation site at the base of the posterior papillary muscle in the LV. All patients had normal LV systolic function and a normal baseline electrocardiogram. The electrocardiogram during VT or PVCs demonstrated a right bundle-branch block and superior-axis QRS morphology in all patients. VT was not inducible by programmed atrial or ventricular stimulation. In 2 patients with sustained VT, overdrive pacing neither terminated VT nor demonstrated any criterion for transient entrainment. Activation mapping localized the earliest site of activation to the base of the posterior papillary muscle in all patients. When Purkinje potentials were recorded at the site of successful ablation, these potentials preceded local ventricular muscle potentials during sinus rhythm. During VT or PVCs, however, the ventricular muscle potential always preceded the Purkinje potentials. After recurrence of VT or PVCs with standard radiofrequency ablation, irrigated ablation was successful in eliminating the arrhythmia in all patients. Over a mean follow-up period of 9 months, all patients have been free of PVCs and VT. Conclusion—We present a distinct syndrome of VT arising from the base of the posterior papillary muscle in the LV by a nonreentrant mechanism. Ablation can be challenging, and irrigated ablation may be necessary for long-term success.

Electrocardiographic characteristics of ventricular arrhythmias originating from the junction of the left and right coronary sinuses of Valsalva in the aorta: the activation pattern as a rationale for the electrocardiographic characteristics.

BACKGROUND Ventricular arrhythmias (VAs) may arise from the aortic sinuses and have electrocardiographic and electrophysiological characteristics that suggest a left (LCC) or right coronary cusp (RCC) origin. However, VAs that arise near the junction of those two cusps (L-RCC) may have unusual features. OBJECTIVES The purpose of this study was to examine the electrocardiographic and electrophysiological characteristics of VAs arising from the L-RCC. METHODS We studied 155 patients with idiopathic VAs with either left or right bundle branch block and an inferior QRS axis morphology and five control subjects undergoing a pacing study. RESULTS For 146 of the 155 patients, the origin determined by the successful ablation site was at the L-RCC in five, LCC in 13, RCC in six, non-coronary cusp in two, right ventricular outflow tract in 108, left ventricular outflow tract in five, left ventricular epicardium in four, and pulmonary artery in three. A qrS pattern in leads V1-V3 was observed only in the VAs with an L-RCC origin. The propagation map revealed that the direction of the propagating wave front from the L-RCC origin produced a vector compatible with a q wave and that the anterior activation to the right ventricular outflow tract via the LCC or RCC formed the r wave. Pacing performed at multiple sites in the aortic root in the control subjects demonstrated that only pacing from the L-RCC could reproduce a qrS pattern in leads V1-V3. CONCLUSIONS This study revealed that a qrS pattern in leads V1-V3 suggests a site of origin at the L-RCC.

Catheter ablation of ventricular arrhythmias originating in the vicinity of the His bundle: Significance of mapping the aortic sinus cusp

BACKGROUND There is a close anatomical relationship between the right coronary cusp (RCC) and noncoronary aortic cusp (NCC) and sites recording His bundle (HB) activation in the right ventricle (RV). OBJECTIVE The purpose of this study was to examine the electrocardiographic and electrophysiological characteristics of ventricular arrhythmias (VAs) that originate near the HB and their potential as predictors of successful catheter ablation sites. METHODS We studied 147 consecutive patients undergoing successful catheter ablation of idiopathic VAs originating from the ventricular outflow tract of either ventricle or the HB region. RESULTS In 13 (9%) patients with an origin in the RCC (n = 5), NCC (n = 1), or RV HB region (n = 7), the local RV activation in the HB region preceded the QRS onset. In two VAs originating from the RCC or NCC, failed radiofrequency applications near the HB region in the RV delayed the near-field ventricular electrogram and separated the far-field electrograms before the QRS onset in the HB region. The QRS transition in the precordial leads did not discriminate between an RV origin near the HB and an NCC or RCC origin. A QS pattern in lead aVL might be helpful for predicting an RCC origin. CONCLUSIONS VAs originating near the HB have similar electrocardiographic and electrophysiological characteristics, regardless of whether the ablation site is in the RV or aortic sinuses because of the close anatomical relationship of these structures and rapid transseptal conduction. When RV mapping reveals an earliest ventricular activation in the HB region during VAs, mapping in the RCC and NCC should be added to accurately identify the site of origin.

Efficacy of electroanatomic mapping in the catheter ablation of premature ventricular contractions originating from the right ventricular outflow tract

BackgroundMapping of premature ventricular contractions (PVCs) originating from the right ventricular outflow tract (RVOT) sometimes is not easy because of an unstable incidence and multiple foci of the PVCs. The aim of this study was to evaluate the effectiveness of electroanatomic mapping in catheter ablation of those PVCs.Methods and resultsOne hundred patients with 134 RVOT origin PVCs were randomly allotted to undergo either conventional (group I; 50 patients with 65 PVCs) or electroanatomic mapping (group II; 50 patients with 69 PVCs). In group II, electroanatomic mapping of the RVOT was performed using auto-freeze maps in patients with frequent PVCs, and pace mapping was performed marking the pacing sites on the remap which was made by extracting the anatomic frame out of the baseline map during sinus rhythm in patients with infrequent PVCs. Successful ablation was achieved in 44 (88%) group I patients and 48 (96%) group II patients (p = 0.14). The fluoroscopy and procedure times and those per PVC morphology were all significantly shorter in group II than group I overall (p < 0.0001 for all comparisons), and in each patient group with infrequent PVCs, frequent PVCs or unstable PVCs (p < 0.05–0.0001). The number of RF applications and that per PVC was significantly smaller in group II than group I (5.3 ± 1.8 vs 6.2 ± 2.4, and 4.4 ± 1.2 vs 5.2 ± 2.1; p < 0.05).ConclusionsThe use of electroanatomic mapping may reduce the fluoroscopy and procedure times in the ablation of RVOT PVCs, but there is no evidence that it improves the overall efficacy of the procedure.

Usefulness of three posterior chest leads for the detection of posterior wall acute myocardial infarction.

A significant proportion of patients with myocardial infarction are missed upon initial presentation to the emergency department. The 12-lead electrocardiogram (ECG) has a low sensitivity for the detection of acute myocardial infarction, especially if the culprit lesion is in the left circumflex artery (LCA). This study was designed to evaluate the benefit of adding 3 posterior chest leads on top of the 12-lead ECG to detect ischemia resulting from LC disease, using a model of temporary balloon occlusion to produce ischemia. We studied 53 consecutive patients who underwent clinically indicated coronary interventions. At the time of coronary angiography, the balloon was inflated to produce complete occlusion of the proximal LCA. We recorded and analyzed the changes noted on the 15-lead ECG, which included 3 posterior leads in addition to the standard 12 leads. In response to acute occlusion of the LCA, the posterior chest leads showed more ST elevation than the other leads, and more patients had ST elevation in the posterior leads than in any other lead. The 15-lead ECG was able to detect>or=0.5 mm (74% vs 38%, p<0.0001) and >or=1 mm (62% vs 34%, p<0.0001) ST elevation in any 2 contiguous leads more frequently than the 12-lead ECG. In conclusion, the 15-lead ECG identified more patients with posterior myocardial wall ischemia because of temporary balloon occlusion of the LC than the 12-lead ECG. This information may enhance the detection of posterior MI in the emergency department and potentially facilitate early institution of reperfusion therapy.

Successful catheter ablation of atrial fibrillation in a patient with dextrocardia

A 49-year-old woman with dextrocardia and situs inversus underwent catheter ablation of paroxysmal atrial fibrillation. A contrast injection into the left atrium revealed that the left atrial appendage (LAA) was adjacent to the right-sided (anatomic left) superior pulmonary vein (PV). After successful isolation of that PV, LAA potentials were recorded from several electrode pairs of a circular PV mapping catheter. LAA may cause similar difficulties during PVI of the right-sided superior PV in a dextrocardia patient, as during PVI of the left superior PV in a normal heart.

Focal ventricular arrhythmias originating from the left ventricle adjacent to the membranous septum.

AIMS We report the features of focal ventricular arrhythmias (VAs) arising from the left ventricle (LV) adjacent to the membranous septum. METHODS AND RESULTS We studied eight patients (five men, 65 ± 10 years) with (n = 2) or without structural heart disease (n = 6) who had ventricular tachycardia (n = 4) or premature ventricular contractions (n = 4) originating from the LV septum underneath the aorta. Ventricular arrhythmias exhibited a focal activation pattern, left (n = 4) or right bundle branch block (n = 4), respectively, left superior (n = 4) or inferior axis QRS morphology (n = 4), negative QRS polarity in lead III and early or no precordial transition in all. During all of these VAs, far-field electrograms in the His bundle (HB) region preceded the QRS onset. In all patients, ventricular pre-potentials were recorded during VAs while late potentials were recorded in sinus rhythm at the border of a localized low-voltage area underneath the aorta. Radiofrequency catheter ablation at the presumed sites of origin successfully eliminated VAs in five patients and was abandoned in the remaining three because the HB electrogram was recorded at that site. CONCLUSION Focal VAs may arise from the LV adjacent to the membranous septum as a part of the LV ostium, and broadens the spectrum of LV ostium VAs.

Regional Variation in Capture of Fibrillating Swine Left Ventricle During Electrical Stimulation

Introduction: While it has been shown that electrical stimulation can capture a region of myocardium during ventricular fibrillation (VF), the ideal location to stimulate to maximize capture of the fibrillating in vivo left ventricle (LV) is not known. We previously demonstrated a mean directionality to the propagation of VF wavefronts in swine from posterior to anterior LV. We hypothesized that this directionality of VF wavefronts would affect capture of the LV epicardium while stimulating during VF.

QRS alternans during idiopathic ventricular tachycardia originating from the right coronary cusp of the aorta

A 77-year-old man underwent electrophysiological testing for idiopathic ventricular tachycardia (VT) with QRS alternans exhibiting a left bundle branch block and left inferior axis QRS morphology. Successful radiofrequency catheter ablation was achieved at the site of the earliest ventricular activation in the right coronary cusp. Pacing at this site reproduced an excellent pace map with QRS alternans. Pacing from other sites in the ventricular outflow tracts reproduced neither an excellent pace map nor QRS alternans. This case demonstrates that VT with a single origin and multiple exits in the aortic root may exhibit QRS alternans.

Left ventricular lead implantation in an unusual anatomy of the proximal coronary sinus.

A 62-year-old man with Class III heart failure and left bundle branch block underwent cardiac resynchronization therapy. Because prior implantation attempts from the left side were unsuccessful, the right side approach was attempted. However, it was still impossible to advance the pre-shaped sheaths into the distal coronary sinus (CS) because the CS was abnormal with a posterior vertical take off followed by a sharp sigmoid curve before the AV groove. Ultimately, a straight sheath was adjusted to fit the sigmoid curve with the guidance of an electrophysiologic catheter and a left ventricular lead was then passed into the anterolateral vein.