Biomedical subjects

Robert F Rea

Publications and source records attributed to Robert F Rea.

9 recordsLinked to original sources

PubMed2005

Left atrial appendage aneurysm.

Aneurysms of the left atrial appendage are exceedingly rare. Patients most commonly present with atrial tachyarrhythmias and thromboembolism. Resection of the aneurysm is usually curative. We present a case report of a 60-year-old female with a long-standing history of atrial arrhythmias found to have a large left atrial appendage aneurysm with additional bi-atrial enlargement and a family history of atrial arrhythmias. The patient was successfully treated with resection of the aneurysm and a Cox-Maze III procedure.

Arrhythmias, Cardiac↗

PubMed2005

Use of advanced mapping systems to guide ablation in complex cases: experience with noncontact mapping and electroanatomic mapping systems.

OBJECTIVE: This report describes our experience with noncontact mapping and electroanatomic mapping in complex ablations, which are defined as ablations done after failure of conventional ablation. MATERIAL AND METHODS: Patients were included (N = 68; 49% with structural heart disease) in whom previous ablation failed and in whom a second procedure was done with advanced mapping. Non-contact mapping was used in 17 patients, electroanatomic mapping in 36, and both noncontact and electroanatomic mapping in 15. Arrhythmias included focal atrial tachycardia (n = 16), reentrant atrial tachycardia (n = 14), right ventricular outflow tachycardia (n = 10), post-myocardial infarction ventricular tachycardia (n = 9), and others (n = 19). RESULTS: Acute success at the second ablation was achieved in 79% of patients. At 20 +/- 9 months after the procedure, 69% of these patients reported having significantly fewer symptoms than before the second ablation, and 51% were free of symptoms. Only 16% were using antiarrhythmic medications. Complications included a small pericardial effusion in two patients, hypotension in one patient, and a femoral pseudoaneurysm in another. CONCLUSIONS: Advanced mapping is a useful and safe adjunct for catheter ablation after ablation has failed in patients with complex substrate.

Arrhythmias, Cardiac↗

PubMed2005

Outcomes after cardiac perforation during radiofrequency ablation of the atrium.

BACKGROUND: Perforation during catheter procedures in either the atrium or ventricle is relatively uncommon, but potentially fatal if tamponade ensues. This study analyzes the occurrence and outcomes of cardiac perforation during catheter-based radiofrequency ablation procedures in the left atrium. METHODS: All patients with a periprocedure perforation who have undergone radiofrequency ablation for atrial fibrillation (AF) or tachycardia were included. RESULTS: Of 632 procedures performed from January 1999 to October 2004, 15 (2.4%) were complicated by perforation requiring pericardiocentesis. The perforation site was left atrium in 9 (60.0%), right atrium in 1 (6.7%), and right ventricle in 5 (33.3%). Intracardiac echocardiography was used in 13 (86.7%) and revealed an effusion before overt instability in 11 (73.3%). Thirteen (86.7%) patients developed a blood pressure <60 mmHg. The pressure stabilized in all patients after pericardiocentesis (hypotension to intervention: 10.1 +/- 5.1 minutes). The total blood volume removed was 848 +/- 880 mL (left atrium/right atrium: 1,074 +/- 1,002 vs right ventricle: 396 +/- 266, P = 0.168). Two patients required surgery to close left atrium dome perforations. The ablation was completed in 7 (46.7%) patients. Ten (66.7%) later developed early reoccurrence of AF. All patients were neurologically intact at hospital discharge. During a 1.5 +/- 1.1 year follow-up, AF was eliminated (n = 4) or controlled (n = 1) in 5 (71.4%) patients with complete procedures, and 2 (20.0%) patients underwent successful repeat ablation. CONCLUSION: The incidence of perforation during ablation of the left atrium is low. Most perforations occur in the left atrium; however, few require surgical closure. Although less than with uncomplicated procedures, the majority of patients with complete ablations achieve long-term elimination of AF.

Adult↗

PubMed2004

Upper limit of vulnerability determination during implantable cardioverter-defibrillator placement to minimize ventricular fibrillation inductions.

The defibrillation threshold (DFT) and upper limit of vulnerability (ULV) were determined using step-down protocols in 50 patients who underwent implantable cardioverter-defibrillator placement or testing. The sensitivity and specificity of each ULV energy level was assessed for detecting an increased DFT, correlation of the DFT and ULV, and optimal shock timing for ULV determination. A ULV <10 or 11 J (failure to induce ventricular fibrillation with 10- to 11-J shocks) was 100% predictive of an acceptable DFT and may be sufficient to exclude unacceptable DFTs in 60% of implantable cardioverter-defibrillator recipients. All 4 shocks used to scan the peak of the T wave during ULV testing were necessary for accurate ULV determination.

Aged↗

PubMed2004

Paradoxical undersensing due to quiet timer blanking.

A case of undersensing of atrial activity by a dual chamber pacemaker is presented. Programming to more sensitive voltages exacerbated undersensing, and programming to less sensitive levels resolved the undersensing. The mechanism by which pacemaker sense amplifiers function to create apparent paradoxical undersensing is reviewed.

Aged↗

PubMed2002

Sudden death after radiofrequency ablation of the atrioventricular node in patients with atrial fibrillation.

OBJECTIVES: We evaluated the incidence and predictors of sudden death after atrioventricular (AV) node ablation and pacemaker implantation. BACKGROUND: Sudden death may occur after radiofrequency catheter ablation of the AV node and pacemaker implantation in patients with atrial fibrillation (AF). Whether it is related to the procedure or to pre-existing heart disease remains unclear. METHODS: All patients who had radiofrequency catheter ablation of the AV node and pacemaker implantation for rate control of medically refractory AF were identified retrospectively and observed prospectively. All patients with sudden death after ablation were identified. The relationship between the procedure and sudden death was defined on the basis of the time between the two as "likely," "possibly" or "unlikely." RESULTS: Of 334 consecutive patients with AF who underwent AV node ablation, nine had sudden death after the ablation. Four patients (1.2%) had sudden death likely related to the procedure: in 3 patients, arrest occurred within 48 h after the procedure; in one patient, arrest occurred four days after the procedure. In three other patients (0.9%), sudden death was possibly related to the procedure because the event occurred within three months afterward. The remaining two deaths were unrelated to the procedure. Diabetes, New York Heart Association functional class (>or=II), preprocedure ventricular arrhythmia, mitral or aortic stenosis, aortic regurgitation and chronic obstructive pulmonary disease were independent predictors for sudden death. CONCLUSIONS: Sudden death likely or possibly related to catheter ablation occurred in 7 of 334 patients (2.1%). Risk of sudden death is highest within two days after the procedure.

Aged↗

PubMed2002

Noncontact mapping to guide ablation of right ventricular outflow tract tachycardia.

OBJECTIVES: [corrected] The aim of this study was to determine whether noncontact mapping is feasible in the right ventricle and assess its utility in guiding ablation of difficult-to-treat right ventricular outflow tract (RVOT) ventricular tachycardia (VT). BACKGROUND: In patients without inducible arrhythmia, RVOT VT may be difficult to ablate. Noncontact mapping permits ablation guided by a single tachycardia complex, which may facilitate ablation of difficult cases. However, the mapping system may be geometry-dependent, and it has not been validated in the unique geometry of the RVOT. METHODS: Ten patients with left bundle inferior axis VT, no history of myocardial infarction and normal left ventricular function underwent noncontact guided ablation; seven had failed previous ablation and three had received a defibrillator. All noncontact maps were analyzed by a blinded reviewer to determine whether the arrhythmia focus was epicardial and to predict on the basis of the map whether arrhythmia would recur. RESULTS: The procedure was acutely successful in 9 of 10 patients. During a mean follow-up of 11 months, 7 of 9 patients remained arrhythmia-free. Both patients in whom the blinded reviewer predicted failure had arrhythmia recurrence: one due to epicardial origin with multiple endocardial exit sites and one due to discordance between site of lesion placement and earliest activation on noncontact map. CONCLUSIONS: Mechanisms of ablation failure in RVOT VT include absence of sustained arrhythmia, difficulty with substrate localization and epicardial origin of arrhythmia. In this study, noncontact mapping was safely and effectively used to guide ablation of patients with difficult-to-treat RVOT VT.

Adult↗

PubMed2002

Progressive isthmus delay during atrial flutter ablation: the critical importance of isthmus spanning electrodes for distinguishing pseudoblock from block.

Bidirectional isthmus block is associated with successful atrial flutter ablation, whereas creation of increased isthmus conduction delay without block can be proarrhythmic. Often, halo catheter electrodes fail to provide adequate sub-Eustachian isthmus recordings. The aim of this study was to determine if progressive isthmus conduction delay results in the false appearance of block during atrialflutter ablation. A 20-pole deflectable catheter was prospectively positioned across the sub-Eustachian isthmus (from the coronary sinus os [CSO] to 7:00 on the tricuspid valve annulus [TVA] clock face in the left anterior oblique [LAO] projection) in nine patients undergoing atrial flutter ablation. During sinus rhythm, conduction time was measured from the CSO to the 7:00 position while pacing the CSO. Measurements were repeated after each linear lesion and after conduction block was achieved. Transisthmus conduction time at baseline, just prior to success, and after the presence of complete block was 54 +/- 9, 123 +/- 39, and 155 +/- 30 ms, respectively (P < or = 0.01). The marked delay prior to complete block resulted in reversal of the activation sequence in electrodes at TVA 7:00, creating the false appearance of isthmus block; the isthmus electrodes clearly distinguished delay from block. Catheter ablation results in progressive isthmus conduction delay prior to the creation of complete block. Electrodes spanning the isthmus and line of block are critical for distinguishing conduction delay (and pseudoisthmus block) from block.

Adult↗

PubMed2002

Unintentional deactivation of implantable cardioverter-defibrillators in health care settings.

Patients with implanted pacemakers and defibrillators are routinely cautioned regarding exposure to environmental magnetic fields because such exposure may interfere with device function. Previous reports have confirmed interference with bingo wands, stereo speakers, and various workplace sources. In the 4 patients in this report, we document inadvertent alteration of the tachyarrhythmia detection function of implantable cardioverter-defibrillators (ICDs) that occurred in health care settings because of deliberately applied magnetic fields. Three of these patients had pectorally implanted ICDs that may have been confused with pacemakers, and 2 patients had undergone office surgical procedures at which time a magnet had been applied over the device. These events stemmed from (1) potential confusion by health care workers about the nature of the implanted device and (2) unique features in a specific manufacturer's defibrillator. We recommend the following steps to avoid such problems: (1) when device programming hardware and trained personnel are readily available, the patient's device should be interrogated and reprogrammed before and after any procedure involving electrocautery; (2) patients with ICDs should be monitored during device inactivation because they are unprotected from potentially life-threatening arrhythmias during this period; and (3) if the clinical situation does not allow device interrogation and reprogramming, the patient should be monitored electrocardiographically during magnet application and the device interrogated as soon as possible after magnet removal.

Aged↗