[Show abstract][Hide abstract] ABSTRACT: Ventricular tachycardia (VT) in patients with prior myocardial damage is generally related to propagation of impulses through surviving myocardial bundles surrounded by and insulated from other fibers by scar tissue. Recurrent VT in these patients is problematic in that, while implantable cardioverter-defibrillators effectively prevent sudden death, they do so at the expense of painful shocks; this, and the fact that medications are generally unsatisfactory at preventing VT episodes in many patients creates a growing need for alternative therapies. Catheter ablation of VT in these patients can be difficult due to varying degrees of hemodynamic compromise during VT as well as the presence of multiple morphologies of VT in most patients and difficulty interpreting complex electrograms during VT. Because of these problems, substrate mapping and ablation (whereby an ablation strategy can be developed without the having the patient spend large amounts of time in VT for detailed mapping of the course of impulse propagation) have assumed an increasingly important role in managing these patients. This chapter explores the pathophysiology of scar-based VT in a variety of substrates and how mapping and ablation strategies based on that information can be tailored to the particular patient's circumstances to obtain optimal results.
[Show abstract][Hide abstract] ABSTRACT: There is controversy whether proceduralist-directed, nurse-administered propofol sedation (PDNAPS) is safe.
To assess the frequency of adverse events when PDNAPS is used for implantable cardioverter-defibrillator (ICD)-related procedures and to determine the patient and procedural characteristics associated with adverse events.
Consecutive ICD-related procedures using PDNAPS from May 2006 to July 2009 at a tertiary-care hospital were evaluated. Serious adverse events were defined as procedural death, unexpected transfer to an intensive care unit, respiratory failure requiring intubation/bag-mask ventilation, or hypotension requiring vasoconstrictor/inotrope support. Nonserious adverse events were defined as hypotension requiring fluid resuscitation or hypoxemia requiring augmented respiratory support with non-rebreather mask, oral airway, or jaw lift.
Of 582 patients (age 64 ± 14 years, 72.3% males) undergoing ICD-related procedures using PDNAPS, 58 (10.0%) patients had serious adverse events with no procedural death and 225 (38.7%) had nonserious adverse events. Longer procedure duration (relative risk [RR] = 2.1 per hour; 95% confidence interval [CI] = 1.6-2.8; P < .001) and biventricular implant (RR = 2.7; CI = 1.4-5.3; P = .003) were independent predictors of serious adverse events. A longer procedure duration (RR = 1.4 per hour; CI = 1.1-1.7; P = .001), heart failure class (RR = 1.4 per 1 class; CI = 1.1-1.7; P = .002), and use of propofol infusion (RR = 3.5; CI = 2.2-5.7; P < .001) were independent predictors of nonserious adverse events.
PDNAPS for shorter ICD procedures including single- and dual-chamber implants, generator changes, and defibrillation threshold testing have acceptable rates of serious adverse events and manageable nonserious adverse events and should be considered for further study. Biventricular implants and other complex procedures should be done with an anesthesiologist.
Heart rhythm: the official journal of the Heart Rhythm Society 03/2012; 9(3):342-6. DOI:10.1016/j.hrthm.2011.10.009 · 5.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We assessed implant rates, indications, characteristics, and outcomes in patients with the neuromuscular disease, myotonic dystrophy type 1 (DM1) receiving a pacemaker or an implantable cardioverter-defibrillator (ICD).
Device use was evaluated in a prospective, multicenter registry of 406 genetically confirmed adult patients followed for 9.5 ± 3.2 years. Forty-six (11.3%) had or received a pacemaker and 21 (5.2%) received an ICD. Devices were primarily implanted for asymptomatic conduction abnormalities and left ventricular (LV) systolic dysfunction. However, 7 (15.2%) pacemakers were implanted for third-degree atrioventricular block and 6 (28.6%) ICDs were implanted for ventricular tachyarrhythmias (ventricular tachycardia [VT] or fibrillation [VF]). Patients receiving devices were older and more frequently had heart failure, LV systolic dysfunction, atrial tachyarrhythmias, and ECG conduction abnormalities compared to nondevice patients. Five (10.9%) pacemaker patients underwent upgrade to an ICD, 3 for LV systolic dysfunction, 1 for VT/VF, and 1 for progressive conduction disease. Seventeen (27.4%) of the 62 patients with devices were pacemaker-dependent at last follow-up. Three (14.3%) ICD patients had appropriate therapies. Twenty-four (52.2%) pacemaker patients died including 13 of respiratory failure and 7 of sudden death. Seven (33.3%) ICD patients died including 2 of respiratory failure and 3 of sudden death. The patients with ICDs and sudden death all had LV systolic dysfunction and 1 death was documented due to inappropriate therapies.
DM1 patients commonly receive antiarrhythmia devices. The risk of VT/VF and sudden death suggests that ICDs rather than pacemakers should be considered for these patients.
[Show abstract][Hide abstract] ABSTRACT: Cardiac tamponade (CT) is a possible complication of radiofrequency catheter ablation (RFCA) of atrial fibrillation (AF). Although the incidence of CT is not higher when RFCA is performed with a therapeutic international normalized ratio (INR), outcomes of CT are unclear.
We compared outcomes among patients with and without a therapeutic INR who developed CT as a complication of RFCA of AF.
The subjects of this retrospective study were 40 consecutive patients who developed CT during RFCA of AF at 3 centers. We divided the patients into 2 groups: RFCA performed with INR < 2 (group 1) and INR ≥ 2 (group 2). There were 23 patients in group 1 and 17 patients in group 2.
Baseline clinical and procedure characteristics were not different between the 2 groups. Heparin was reversed by protamine in 83% and 94% of patients (P = .37), and warfarin was reversed by fresh frozen plasma or factor VIIa in 17% and 35% of patients (P = .27) in groups 1 and 2, respectively. All patients were successfully treated by percutaneous drainage, and none required surgical intervention. There were no significant differences in the amount of initial pericardial drainage (523 ± 349 ml vs. 409 ± 157 ml, P = .22) or the duration of drainage (P = .14) between the 2 groups. All patients survived to hospital discharge. Median length of hospital stay was 2 days longer in group 1 (P <.01).
Cardiac tamponade is not more severe or difficult to manage in the presence of therapeutic anticoagulation with warfarin in patients undergoing RFCA of AF.
Heart rhythm: the official journal of the Heart Rhythm Society 06/2011; 8(6):805-8. DOI:10.1016/j.hrthm.2011.01.020 · 5.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Myotonic dystrophy type 1 (DM1) is a neurologic disorder with known cardiac involvement, including left ventricular systolic dysfunction (LVSD), heart failure (HF), atrioventricular and intraventricular conduction system disease, and sudden death. We studied the prevalence of these conditions and associated findings in a large population with DM1.
History, physical examination, genetic testing, and electrocardiography were performed on 406 patients with DM1, and cardiac imaging was performed on 180 (44.3%) of these patients.
Left ventricular systolic dysfunction and clinical HF were found in 34 (18.9%) of 180 and in 23 (5.7%) of 406 of enrolled subjects, respectively, yielding an overall prevalence of LVSD/HF in 41 (10.1%) of 406. Increasing age, male sex, electrocardiographic conduction abnormalities, presence of atrial and ventricular arrhythmias, and implanted devices were all significantly associated with LVSD/HF, whereas cytosine-thiamine-guanine repeat length and neuromuscular severity score were not. The interval≥240 milliseconds (relative risk 4.1, 95% CI 1.7-9.6, P=.001) and QRS duration≥120 milliseconds (relative risk 4.2, 95% CI 2.0-8.5, P<.001) were significant predictors of LVSD/HF. The presence of LVSD/HF was also significantly associated with all-cause death (relative risk 3.9, 95% CI 2.3-6.4, P<.001) and cardiac death (relative risk 5.7, 95% CI 2.6-12.4, P<.001).
A significant prevalence of LVSD/HF exists in patients with DM1. The presence of LVSD/HF in DM1 is significantly associated with all-cause and cardiac death.
[Show abstract][Hide abstract] ABSTRACT: In recent years, nonpharmacological therapies for atrial fibrillation (AF) have emerged given the limitations of medical therapy. Advancements in particular have been made in the areas of radiofrequency catheter ablation and AF surgery, and have been accompanied by substantial technological improvements. This article will discuss several different modalities of nonpharmacological AF management including catheter ablation, AF surgery and device-based therapy.
[Show abstract][Hide abstract] ABSTRACT: Nonischemic dilated cardiomyopathy (NICM) is associated with diffuse global hypokinesia on echocardiography. However, NICM also may be associated with segmental wall-motion abnormalities (SWMAs) even in the presence of global hypokinesia, probably secondary to patchy myocardial scars.
Because myocardial scars serve as substrate for reentry, the purpose of this study was to determine whether SWMA is a predictor of ventricular arrhythmic events in NICM.
Echocardiographic parameters and appropriate implantable cardioverter-defibrillator (ICD) therapy for arrhythmic events (shock or antitachycardia pacing) were studied in NICM patients with an ICD. Two-dimensional echocardiography of the left ventricle was recorded in a 16-segment model. SWMA was defined by the presence of akinesia or moderate to severe hypokinesia in at least two segments. Patients were divided into one of two groups according to the presence (SWMA group) or the absence (non-SMWA group) of SWMA.
SWMA was present in 47.5% of 101 patients (mean age 58.0 ± 15.6 years, 85% male, primary prophylaxis indication 46%, mean ejection fraction 26% ± 9%, mean follow-up 29 ± 18.4 months) studied. No significant difference in mean age, ejection fraction, and QRS duration was seen between SWMA and non-SWMA groups. The SWMA group had a significantly higher incidence of arrhythmic events than did the non-SWMA group (65% vs 15%, P <.001). Kaplan-Meier survival analysis revealed that SMWA was associated with significantly reduced time to first arrhythmic event (P = .001). SWMA (P <0.001), New York Heart Association heart failure class (P = .016), and secondary prevention indication for ICD placement (P = .005) were significant independent predictors of an arrhythmic event. SWMA did not predict mortality.
SWMA is an independent predictor of arrhythmic events in patients with NICM.
Heart rhythm: the official journal of the Heart Rhythm Society 10/2010; 7(10):1390-5. DOI:10.1016/j.hrthm.2010.05.039 · 5.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Myocardial scar is a substrate for reentrant ventricular arrhythmias and is associated with poor prognosis. Fragmented QRS (fQRS) on 12-lead ECG represents myocardial conduction delays due to myocardial scar in patients with coronary artery disease (CAD).
The purpose of this study was to determine whether fQRS is associated with increased ventricular arrhythmic event and mortality in patients with CAD and nonischemic dilated cardiomyopathy (DCM).
Arrhythmic events and mortality were studied in 361 patients (91% male, age 63.3 +/- 11.4 years, mean follow-up 16.6 +/- 10.2 months) with CAD and DCM who received an implantable cardioverter-defibrillator for primary or secondary prophylaxis. fQRS included various RSR' patterns (QRS duration <120 ms), such as > or =1 R prime or notching of the R wave or S wave present on at least two contiguous leads of those representing anterior (V(1)-V(5)), lateral (I, aVL, V(6)), or inferior (II, III, aVF) myocardial segments.
fQRS was present in 84 (23%) patients (fQRS group) and absent in 100 (28%) patients (non-fQRS group). Wide QRS (wQRS; QRS duration > or =120 ms) was present in 177 (49%) patients. Kaplan-Meier analysis revealed that event-free survival for an arrhythmic event (implantable cardioverter-defibrillator shock or antitachycardia pacing) was significantly lower in the fQRS group than in the non-fQRS and wQRS groups (P <.001 and P <.019, respectively). fQRS was an independent predictor of an arrhythmic event but not of death.
fQRS on 12-lead ECG is a predictor of arrhythmic events in patients with CAD and DCM. fQRS is associated with a significantly decreased time to first arrhythmic event compared with non-fQRS and wQRS.
Heart rhythm: the official journal of the Heart Rhythm Society 01/2010; 7(1):74-80. DOI:10.1016/j.hrthm.2009.09.065 · 5.08 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several mapping techniques are used during catheter ablation of ventricular tachycardia (VT), including activation mapping, pace mapping, entrainment mapping, and substrate mapping. These mapping techniques complement one another, and all of these tools can be used to localize the critical isthmus of a hemodynamically stable sustained reentrant monomorphic VT, whereas activation mapping and pace mapping are the only useful techniques available for localizing the exit sites of a focal VT or frequent symptomatic premature ventricular complexes (PVCs). Pace mapping is performed to replicate 12-lead ECG configuration of a spontaneous or induced VT. If the pace map from the isthmus site of a reentrant VT has a long S-QRS that is similar to the electrogram (Egm) during VT, and yields complete replication of each feature of each ECG lead, it signifies that the catheter is located on the critical isthmus, which is an expected site of successful ablation. Activation and pace mapping of a Purkinje-like potential prior to a PVC that initiates polymorphic VT and ventricular fibrillation is helpful in determining the successful site of ablation of these arrhythmias. Pace mapping is especially useful when VT is hemodynamically unstable because both activation and entrainment mapping require that the VT should be easily inducible, sustained, and hemodynamically stable so that sampling of Egm timing from multiple sites and repeated pacing maneuvers can be performed.