Arthur R. Easley

Usefulness of ibutilide in facilitating successful external cardioversion of refractory atrial fibrillation

We repeated direct-current cardioversion of atrial fibrillation after ibutilide injection in patients who failed conventional cardioversion. Eleven of 12 patients (92%) had successful cardioversion and avoided the need for internal cardioversion.

Potential risk of vasovagal syncope for motor vehicle driving

Vasovagal syncope is the most common cause of syncope, but its risk for driving remains uncertain. We analyzed the clinical characteristics of patients who had syncope during driving and subsequently underwent the head-up tilt test (HUTT). Of the 245 consecutive patients undergoing HUTT, 23 (9%) had > or =1 episode of syncope during driving. HUTT was positive in 19 (group A) and negative in 4 (group B) patients. No patient had structural heart disease. In group A, the driving incident occurred on the first syncope in 3 patients, and the other 16 patients had 1 to 4 episodes of prior syncope not associated with driving. In group B, the driving incident occurred on the first syncope in 1 patient, and the other 3 patients had prior syncope (3 episodes in each) not associated with driving. Seven group A and 1 group B patients had 2 syncope-related driving incidents, and the remaining patients had only 1 syncope-related driving incident. The syncope-related driving incidents caused personal injury in 7 group A and 2 group B patients. One incident in 1 group A patient caused the death of another driver. After HUTT, all but 1 patient in group A received medical treatment and only 1 patient in group B received empirical beta-blocker therapy. During the follow-up of 51+/-26 months, 1 patient died and another was lost to follow-up. Of the remaining patients, 4 patients had recurrence of syncope and 2 patients had presyncope in group A. One of these patients had another syncope-related driving incident. No group B patient had syncope recurrence. A second etiology of syncope was never found in any patient. We conclude that vasovagal syncope during driving is not uncommon in patients referred for syncope evaluation. Early medical attention to patients with vasovagal syncope may help reduce syncope-related driving incidents.

Evaluation and management of atrial fibrillation in the emergency department

AF is the most common sustained cardiac arrhythmia. Recognition and appropriate management of AF is important to optimize care of concurrent medical problems and prevent long-term consequences. DC cardioversion under sedation should be performed in patients with pulmonary edema, angina, or hypotension. Ventricular rate control is the first choice in stable patients with rapid ventricular rate. Anticoagulation should be considered in all patients with AF duration < 48 hours, except for those under 65 years old and having no other risk factors of stroke. Recent data imply that early attempts at cardioversion may increase success rates and decrease AF recurrence rates. Thus, transesophageal echocardiogram-guided early cardioversion may become more widely used.

Defibrillator patch electrode constriction: An underrecognized entity

Pericardial constriction associated with the placement of intrapericardial defibrillator patches is a rare occurrence that is reported only one tenth as often in defibrillator patients as in patients undergoing other types of cardiac operations. Although this discrepancy may be attributable to a lower incidence of constriction with the defibrillator patch electrode procedure, it may also indicate a failure to recognize that progressive right heart failure and signs of low cardiac output that could be due to pericardial constriction and not progressive systolic dysfunction. Because surgical removal of the patches and decortication of the epicardial surface is the only effective therapy, it is important to recognize this uncommon, but profoundly debilitating entity.

The Mean Ventricular Fibrillation Cycle Length: A Potentially Useful Parameter for Programming Implantable Cardioverter Defibrillators

In programming the implantable cardioverter defibrillator (ICD), the ventricular tachycardia (VT) detection cycle length (CL) is based on the CL of the documented tachycardia but the ventricular fibrillation (VF) detection CL is set arbitrarily. Appropriate programming of VF detection may not only reduce the incidence of inappropriate ICD shocks for non‐VF rhythms but can also avoid the fatal underdetection of VF. The mean VFCL may provide a useful parameter for optimal ICD programming for VF detection if it is reproducible. This study examined the intrapatient reproducibility and interpatient variation of the mean VFCL in 30 ICD patients (25 men and 5 women, mean age 63 ± 13 years). A total of 210 VF episodes (7 ± 4 per patient, range 3–17) induced by T‐wave shocks (166) or AC (44) at the ICD implant (30 patients) and the predischarge test (12 of 30 patients) were analyzed. The mean VFCL was calculated from the stored V‐V intervals in the ICDs. Although the mean VFCL varied significantly from 171 ± 6 to 263 ± 11 ms (P < 0.01) among different patients, it was reproducible among different VF episodes in an individual patient (maximal variation 4–50 ms, P > 0.05). The mean VFCL was not significantly different between patients with and without antiarrhythmic drugs (210 ± 32 vs 210 ± 23 ms, P > 0.05) and was correlated with the ventricular effective refractory period (r = 0.5, P < 0.05). The mean VFCL varies greatly among different patients but remains reproducible in an individual patient, suggesting that the mean VFCL may serve as a reference for ICD programming of VF detection.

Clinical Comparison of Acute Single to Dual Chamber Pacing in Chronotropically Incompetent Patients with Left Ventricular Dysfunction

Dual chamber, rate responsive (DDDR) pacing is felt to be superior to ventricular, rate responsive (VVIR) pacing since it more closely mimics the normal electrical and hemodynamic activity of the heart. This reasoning has been used to justify the higher initial costs and increased complexity of dual chamber systems. This study was designed to determine if objective criteria could be identified during acute testing to justify implanting a dual chamber instead of a single chamber system in patients with left ventricular dysfunction. Eight patients with DDDR pacemakers (implanted for chronotropic incompetence) and left ventricular dysfunction underwent exercise radionuclide angiography and graded exercise treadmill testing. Each patient performed the tests in the single (VVIR) and dual (DDDR) chamber modes in a randomized, blinded fashion. We found that objective parameters such as ejection fraction (31%± 13% vs 31%± 10%), exercise tolerance (6.1 ± 2.7 min vs 6.3 ± 2.9 min), oxygen consumption (VO2) (941 ± 286 mL/min vs 994 ± 314 mL/min), carbon dioxide production (VCO2) (995 ± 332 mL/min vs 1054 ± 356 mL/min), and maximum attainable workload (43 ± 24 W vs 46 ± 22 W) did not differ between the single and dual chamber pacing modes. These findings suggest that in the acute setting, the additional cost and complexity of dual chamber, rate responsive pacing cannot be justified by objective improvements in exercise tolerance in patients with underlying left ventricular dysfunction.

Causes and Consequences of Discontinuation of the Implantable Cardioverter-Defibrillator Therapy in Non-Terminally Ill Patients

Infection and implantable cardioverter-defibrillator shocks are important contributing factors to discontinuation of cardioverter-defibrillator therapy in non-terminally ill patients. These patients are at a high risk of sudden cardiac death despite continued antiarrhythmic drug therapy.

Electromagnetic interference from electronic article surveillance system in a patient with a biventricular ICD and a left ventricular assist device.

Case Presentation A 62-year-old man with a history of familial nonischemic dilated cardiomyopathy, sick sinus syndrome, atrial fibrillation, and complete heart block was implanted with a St. Jude Atlas-II HF biventricular implantable cardioverter defibrillator (BiV ICD; St. Jude Medical, St. Paul, MN, USA), with a Guidant 0158 integrated bipolar ventricular lead (Guidant Corp., St. Paul, MN, USA) and a Medtronic 5554 bipolar atrial lead (Medtronic Inc., Minneapolis, MN, USA) in 2006. He had a HeartMate II left ventricular assist device (LVAD; Thoratec Inc., Pleasanton, CA, USA) implantation in March 2009, as bridge to cardiac transplantation for end-stage heart failure. His BiV ICD was programed as follows: DDDR mode with a base rate of 85 beats/min and a maximum track rate of 120 beats per minute (bpm) with paced and sensed atrioventricular delays being 190 ms and 150 ms, respectively. His ventricular noise reversion mode was VOO and atrial tachycardia detection rate was 180 bpm. The “tachy” parameters of the device were programed as follows: ventricular tachycardia (VT)-1 = 440 ms, VT-2 = 315 ms, ventricular fibrillation (VF) = 270 ms, and all zones had to fulfill 12 intervals. He went to a bicycle store, accompanied by his daughter. After they purchased the bicycle and were about to leave the store, he was lingering at the antitheft detection system of the store for approximately 2 minutes. He then experienced an ICD shock. Of note, none of his prior interrogations revealed any problems suggestive of lead fracture.

Options in managing the patient with high defibrillation thresholds

The desired defibrillation threshold (DFT) obtained during intraoperative testing of an implantable cardioverter defibrillator (ICD) should be 10 J lower than the maximal energy delivered by the ICD generator. Of the 206 patients undergoing ICD implantation since December 1986, 8 (3.9%) have had initial DFTs with less than the 10-J safety margin using the standard large patch-large patch configuration. Patches were implanted by left thoracotomy in 6 and sternotomy in 1, and 1 had implantation of a transvenous defibrillation lead and subcutaneous patch. Of note, 6 (75%) of the 8 patients with high DFTs had prior open heart operations, half were on a regimen of long-term amiodarone therapy, and the mean left ventricular mass index was quite large but not significantly greater than that of patients with low DFTs. Multiple techniques was tried to improve the DFTs in this group. Satisfactory DFTs were eventually obtained in 7 (88%); the threshold was lowered from a mean of 41.4 +/- 3.8 J to 26.9 +/- 8.8 J (p = 0.002). The most effective techniques were addition of a superior vena cava lead attached by a Y connector to one of the large patch leads in some patients and conversion to a biphasic-waveform generator in 2 others. Adding a third epicardial lead did not lower the DFTs. There were no major postoperative complications or deaths attributable to these supplemental procedures. Using these techniques, satisfactory DFTs were obtained in almost all patients with an ICD.(ABSTRACT TRUNCATED AT 250 WORDS)

Pacemaker-induced inappropriate implantable cardioverter-defibrillator shock: An unusual case of arrhythmia induction

Case summary S.S., a 38-year-old man, struck a cow while driving his vehicle. After the accident, while he was outside the vehicle inspecting the situation, he was anxious and shook his fist in frustration. He felt palpitations and associated dizziness. Almost immediately, he received an implantable cardioverter-defibrillator (ICD) shock that resolved the palpitations. No further sequelae occurred. He presented to our electrophysiology clinic for evaluation. S.S. has a history of nonischemic cardiomyopathy with bradycardia and is status postimplantation of a dual-chamber, biventricular Boston Scientific Contak Renewal 3 ICD. The ICD had been placed 4 years earlier for primary prevention due to viral dilated cardiomyopathy. The atrial lead is a Guidant 4136, the right ventricular lead is a Guidant 0185 integrated bipolar lead, and the left ventricular lead is a St. Jude 1056T bipolar lead. Device programmed and measured parameters are detailed in Table 1. Since implantation, the patient has experienced occasional episodes of nonsustained ventricular tachycardia (VT), for a total of five ventricular fibrillation (“VF”) events with a cycle length (CL) ranging from 243 to 278 ms. Since ICD implantation, he has received two shocks, one shock was 14 months earlier and the second of the two shocks as described above.