Approach To The Patient With Vf Or Cardiac Arrest
Because cardiac arrest may be a presentation of acute MI, once a patient has been resuscitated, it is critical to determine whether or not the patient is having an acute, transmural i.e., ST elevation or new LBBB MI. VF that occurs within the first 24-48 h of an acute MI is usually considered to be an epiphenomenon of the MI, and as such does not necessarily require long-term treatment specifically focused on ventricular arrhythmia. Patients with acute MI who are resuscitated from VF and who...
Interventional Electrophysiology
The successes of arrhythmia surgery using intra-operative mapping, and the realization that the majority of targets for these techniques were subendocardial or could be mapped via an endocardial approach, led to efforts to ablate arrhythmogenic foci using percutaneous, catheter-based techniques. Initial catheter ablation procedures used high-energy direct current to fulgurate endocardial tissue. This technique, initially introduced Fig. 2. Left ventricular endocardial mapping schema published...
Sustenance
Like other percutaneous interventions in cardiovascular medicine, it was the development of a surgical procedure which ushered in the era of catheter ablation for AF sustenance. Utilizing the concepts of multiple wavelet reentry, Cox et al. hypothesized that if the atrium were sectioned in order to limit the region of contiguous conduction, Fig. 8. Initiation of af oy a period ot repetitive firing asterisks emanating from the right superior pulmonary vein. The firing is irregular at times. In...
Pathophysiology
Any tachyarrhythmia that requires atrial and or AV junctional tissue for its initiation and maintenance can properly be considered a supraventricular tachyarrhythmia. Ventricular tachyarrhythmias, conversely, require only ventricular tissue for their initiation and maintenance. Supraventricular tachyarrhythmias can be divided into those that require only atrial tissue atrial tachyarrhythmias and those that require AV junctional tissue see Table 1 . Supraventricular tachycardia SVT may be...
Dofetilide in Patients With Structural Heart Disease
Recently, dofetilide, a pure class III agent devoid of beta-blocker activity, has been shown to have a mortality-neutral effect in patients with low ejection fractions. A recent placebo-controlled trial of over 1500 patients with severe left ventricular dysfunction and CHF demonstrated that dofetilide was effective in converting patients to sinus rhythm, maintaining sinus rhythm, and reducing the risk of hospitalizations for CHF with no increase in mortality 87-88 . There is, however, a...
A Review Of Right Atrial Anatomy
Because atrial flutter is usually confined to the right atrium, an appreciation of the anatomy of the endocardial surface of the right atrium is essential. The interior surface of the right atrium can be divided into three regions a smooth-walled venous component derived from the embryonic sinus venosus a trabeculated atrium proper and the right atrial appendage 33 . The crista terminalis is a ridge on the internal surface of the right atrium which is located lateral to the superior vena cava...
External and Internal Cardioversion and the Atrial Defibrillator
Transthoracic cardioversion of AF has been achieved successfully for several decades, with success rates reported to be from 70-95 . However, in a small minority of patients, even with the addition of antiarrhythmic drugs to lower the defibrillation threshold, this strategy can fail. More recently, new techniques have been developed to rescue the patients who have failed conventional cardioversion. Externally, one can attempt to increase the current delivered to overcome the high transthoracic...
Prognosis
NSVT is one of several risk factors for sudden death and death resulting from heart disease, but by itself, NSVT has little predictive value 35-37 . In combination with specific conditions acute MI, hypertrophic cardiomyopathy, impaired left ventricular function caused by CAD or LQTS , NSVT can be a major concern 38-42 . In a normal population, NSVT recorded on a Holter monitor is associated with a significantly higher risk of early death, although causality has not clearly been established....
Temporary Pacing
Temporary transvenous pacing is an established technique that can most often be accomplished quickly and easily by appropriately trained individuals. It is often performed under direct fluoroscopic visualization, but positioning flow-directed balloon catheters using electrocardiographic guidance is an acceptable alternative when fluoros-copy is unavailable. There are a number of indications for temporary pacing. In general, temporary pacing is indicated in any person who is markedly symptomatic...
Prolonged Qt Syndrome
QT interval prolongation on the standard 12-lead ECG is the hallmark of a heterogeneous group of disorders characterized by malignant ventricular arrhythmias typically torsades de pointes and a high incidence of syncope and sudden cardiac death Fig. 4 . Although congenital long QT syndrome LQTS was originally reported in children as a genetically transmitted disorder, acquired forms of LQTS have also been described. The pathogenesis of the arrhythmias associated with QT prolongation is...
References Lae
1. Savage DD, Carwin L, McGee DL, Kennel WB, Wolf PA. Epidemiologic features of isolated syncope. The Framingham Study. Stroke 1985 16 626-629. 2. Olshansky B. Syncope An overview and approach to management. In Grubb BP, Olshansky B, eds. Syncope Mechanisms and Management. Futura Publishing Co. Inc., Armonk, NY, 1998, pp. 15-71. 3. Day SC, Cook EF, Funkenstein H, Goldman L. Evaluation and outcome of emergency room patients with transient loss of consciousness. Am J Med 1982 73 15-23. 4....
Postinfarction Arrhythmia Management
VF and sustained VT occurring late gt 48 h in the course of an AMI suggest an ominous prognosis. Among 390 patients in a multicenter Dutch study, 49 had recurrent VT or VF over a mean follow-up period of 1.9 yr. Nineteen percent died because of recurrent VT or VF, and the total mortality during this period was 34 146 . Thus, late ventricular arrhythmias during AMI suggest a high risk for arrhythmia recurrence. As with VT and VF not temporarily related to AMI, the therapeutic approaches are the...
Direct Current Cardioversion
position. The need for an adequacy of anticoagulation should be considered in any patient undergoing cardioversion this issue is explored in Chapter 6. Just as a biphasic waveform markedly improved the ventricular defibrillation efficacy of implantable cardioverter defibrillators ICD , biphasic cardioversion is more effective at restoring sinus rhythm than monophasic waveforms. In a randomized trial, Mittal and colleagues found that rectilinear biphasic shocks restored sinus rhythm in 94 of...
References 1
1. Zimetbaum P, Josephson ME. Evaluation of patients with palpitations. N Engl J Med 1998 338 1369-1373. 2. Kapoor WN, Karpf M, Wieand S, Peterson JR, Levey GS. A prospective evaluation and follow-up of patients with syncope. N Engl J Med 1983 309 197-204. 3. Day SC, Cook EF, Funkenstein H, Goldman L. Evaluation and outcome of emergency room patients with transient loss of consciousness. Am J Med 1982 73 15-23. 4. VarmaN, Josephson ME. Therapy of idiopathic ventricular tachycardia. J Cardiovasc...
Info Esp
126 . The prevalence is likely higher when IMI is complicated by right ventricular infarction 13,127,128 . CHB in IMI is frequently transient the median duration in the TAMI cohort was 2.5 h 126 . In the TIMI II study, there was a trend toward more second- and third-degree heart block in IMI patients who received iv beta-blockade 129 . Although patients with CHB had a higher in-hospital mortality, there was no difference in long-term follow-up in patients who survived until discharge. The...
Atrioventricular Nodal Reentrant Tachycardia
Atrioventricular nodal reentrant tachycardia AVNRT is a common arrhythmia, comprising approx 60 of cases of PSVT referred for electrophysiology testing. It occurs in patients with two functionally distinct conduction pathways through the AV node, referred to as the fast and slow pathways. The slow pathway has a shorter refractory period than the fast pathway. Both the fast and slow pathway are necessary to maintain AVNRT. The common form of AVNRT is typically initiated when an atrial premature...
Info Sdr
Fig. 3. Electrocardiographic presentation of AF with rapid, irregular pre-excited conduction in a patient with WPW. Fig. 3. Electrocardiographic presentation of AF with rapid, irregular pre-excited conduction in a patient with WPW. L-TGA , which has a frequent finding of Ebstein's malformation of the left-sided tricuspid valve. Other forms of congenital heart disease do not appear to be clearly associated with an increased prevalence of accessory pathways, but they may be present in some...
Future Developments In Catheter Ablation Of Supraventricular Arrhythmias
The single greatest limitation of current ablation technologies is the inability to cure AF with catheter ablation. A surgical technique to cure AF, called the Maze procedure, has been developed 82 . The procedure is performed by creating multiple linear incisions in the right and left atrium to interrupt conduction through the most common reentrant circuits during AF. Among 164 patients, followed for at least 3 mo, AF was eliminated in 152 93 . Recently, preliminary reports have described...
References Jeh
1. Bialy DLM, Schumacher DN, Steinman RT, Meissner MD. Hospitalization for arrhythmias in the United States the importance of atrial fibrillation. J Am Coll Cardiol 1992 19 Abst . 2. Falk RH. Atrial fibrillation. N Engl J Med 2001 344 14 1067-1078. 3. Farshi R, Kistner D, Sarma JSM, Longmate JA, Singh BN. Ventricular rate control in chronic atrial fibrillation during daily activity and programmed exercise a crossover open-label study of five drug regimens. J Am Coll Cardiol 1999 33 304-310. 4....
Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy is a disorder of the myocardium characterized by excessive hypertrophy of the left ventricle, especially the interventricular septum. Although in theory there is an obstructive characterized by a measurable left ventricular outflow gradient and a nonobstructive form, the distinction between them may be difficult to discern because the gradient is dynamic and is dependent upon preload and the level of sympathetic tone. Both forms of hypertrophic cardiomyopathy are...
Classification Of Nsvt
NSVT can be categorized by morphology, clinical presentation, underlying substrate, and symptoms. Nonsustained tachycardias may present many appearances. The possibility that a nonsustained wide-complex tachycardia may be caused by supraventricular tachycardia with aberrancy should also be considered see Fig. 2B . Multiple algorithms have been proposed to aid in diagnosis from a practical perspective, wide-complex tachycardia is more likely VT than SVT with aberrancy, particularly in patients...
References Yke
1. Stoddard MF, Pawking PR, Prince CK, and Ammash NM, et al. Left atrial appendage thrombus is not uncommon in patients with acute atrial fibrillation and a recent embolic event a transesophageal echocardiography study. JACC 1995 25 452-459. 2. Weigner N, Caulfield TA, Danias PG, Silverman DJ, and Manning WJ. Risk for clinical thromboembolism associated with conversion to sinus rhythm in patients with atrial fibrillation lasting less than 48 hours. Ann Intern Med 1997 126 615-620. 3. Botto GL...
Info Ydu
Fig. 4. CABG Patch results Actuarial survival curves for patients treated with the defibrillator and with conventional therapy. See text. From Bigger TJ, for the Coronary Artery Bypass Graft CABG Patch Trial Investigators. Prophylactic use of implanted cardiac defibrillators in patients at high risk for ventricular arrhythmias after CABG surgery. N Engl J Med 1997 337 1569-1575. Copyright 1997 Massachusetts Medical Society. inducible ventricular arrhythmia during electrophysiologic studies. The...
A Kio
A Monomorphic NSVT in a patient with ischemic cardiomyopathy. The patient fit the MADIT MUSTT profile. During EPS, rapid VT was induced, and the patient received an ICD. B Monomorphic NSVT in a patient with underlying nonischemic cardiomyopathy and AF. Note that the PVC that initiates NSVT has a different morphology than the subsequent salvo of NSVT. C Torsades de pointes PVT in a patient with acquired LQTS caused by quinidine therapy. Note the recurrent paroxysms of NSVT following long-short...
References Vlb
1. Ganz LI, Friedman PL. Supraventricular tachycardia. N Engl J Med 1995 332 162-173. 2. Lesh MD, Van Hare GF, Epstein LM, et al. Radiofrequency catheter ablation of atrial arrhythmias results and mechanisms. Circulation 1994 89 1074-1089. 3. Krahn AD, Yee R, Klein GJ, Morillo C. Inappropriate sinus tachycardia evaluation and therapy. J Cardiovasc Electrophysiol 1995 6 1124-1128. 4. Gomes JA, Mehta D, Langan MN. Sinus node reentrant tachycardia. PACE 1995 18 1045-1057. 5. Kastor RA. Multifocal...
Walter L Atiga MD and Hugh Calkins MD
Catheter Ablation of Supraventricular Arrhythmias of Supraventricular Arrhythmias Paroxysmal Supraventricular Tachycardias Atrial Arrhythmias Special Considerations During Catheter Ablation of Supraventricular Arrhythmias in Children Cost-Effectiveness of Catheter Ablation Future Developments in Catheter Ablation of Supraventricular Arrhythmias References
Transition
Hypothetically, during the evolution from AF initiation to sustenance, an obligatory transitional condition occurs. The condition may involve a relatively uniform rhythm and or a confined anatomical region. The notion of a transitional rhythm is not new. For example, multiple studies have documented patients with both spontaneous paroxysmal supraventricular tachycardia SVT and AF, in whom the latter was believed to occur consistently during the former 32,33 Fig. 6 . Mechanistically, AF...
References Wch
1. Gallagher JJ, Svenson RH, Kassell HJ, German LD, Bardy GH, Broughton A, et al. Catheter technique for closed-chest ablation of the atrioventricular conduction system a therapeutic alternative for the treatment of refractory supraventricular tachycardia. N Engl J Med 1982 306 194-200. 2. Scheinman, Melvin M. NASPE Survey on Catheter Ablation. From the Cardiac EP Service, University of California, San Francisco, CA, PACE. 1995 18 1474-1478. 3. Haines DE, Watson DD, Verow AF. Electrode radius...
Specific Causes Of Syncope
The following sections review some of the various disorders that may result in syncope. Many of these disorders such as VT and heart block are dealt with in greater detail elsewhere in this book and will not be reviewed here. Conditions that are not covered in other sections will be discussed in more detail. Noncardiac causes predominate in patients suffering from recurrent unexplained syncope. Of these, the majority appear to occur because of transient alterations in autonomic nervous system...
Paroxysmal Supraventricular Tachycardias
Paroxysmal supraventricular tachycardias PSVT characteristically begin and terminate abruptly. Electrocardiograms ECGs obtained during PSVT typically reveal a narrow QRS complex with a rate between 130 and 240 beats per minute BPM . Atrioventricular nodal reentrant tachycardia AVNRT is the most common cause of PSVT, accounting for two-thirds of cases. Atrioventricular reciprocating tachycardias AVRT , which involve conduction through both the AV node and an accessory pathway, are the second...
Ventricular Arrhythmias During Acute Mi
The metabolic sequelae of ischemia, including intracellular hypercalcemia and acidosis, anaerobic lipid metabolism, and free-radical production, may contribute to arrhyth-mogenesis during AMI 3 . Rapid efflux of intracellular potassium, leading to membrane depolarization, may be the most important of these effects. In addition, increased sympathetic tone augments electrical instability, provoking both ventricular and supra-ventricular tachyarrhythmias. Enhanced parasympathetic tone, usually...
Introduction Xfw
From Contemporary Cardiology Management of Cardiac Arrhythmias Edited by L. I. Ganz Humana Press Inc., Totowa, NJ Fig. 1. Density of ventricular ectopy in unselected patients undergoing 24-h Holter monitoring as a function of age. From Kostis JB. Circulation 1981 63 1353. Fig. 1. Density of ventricular ectopy in unselected patients undergoing 24-h Holter monitoring as a function of age. From Kostis JB. Circulation 1981 63 1353. The actual incidence of NSVT in the general population is unknown...
Potential Treatments
A complete discussion of the treatment options available is beyond the scope of this chapter however, some basic principals are briefly outlined 75 . One of the physician's most important tasks is to identify whether hypotensive syncope is primary or secondary in nature, and to determine if there are any potentially reversible causes such as drugs, anemia, or volume depletion see Table 6 . It is equally important to educate the patient and their family about the nature of the problem. Teaching...
Epidemiology Of Arrhythmias During Pregnancy
An increased incidence of maternal cardiac arrhythmias is observed during pregnancy. This includes episodes of paroxysmal supraventricular tachycardia PSVT in patients with the Wolff-Parkinson-White syndrome WPW and new-onset idiopathic ventricular tachycardia VT 5-7 . The increase in arrhythmias is explained in part by the metabolic, hormonal, and hemodynamic changes of pregnancy. In addition, advances in cardiac surgery have allowed an increased number of women with congenital cardiac...
Acute Management
Although direct current cardioversion will terminate most PSVTs, this is rarely necessary, as the vast majority of patients are hemodynamically stable. In stable patients with regular SVTs, vagal maneuvers may be attempted initially 31 . If vagal stimuli are unsuccessful in terminating tachycardia, an intravenous IV AV-nodal-blocking agent should be administered see Fig. 10 . Adenosine 32 and verapamil appear to be of similar efficacy in terminating PVSTs that require AV-nodal conduction....
Atrial Flutter
Atrial flutter is an atrial arrhythmia characterized by uniform morphology and a rate that is regular and greater than 240 BPM. It is often accompanied by a fixed 2 1 ventricular response, and it is this rapid ventricular response that results in the majority of symptoms. It may be observed transiently following cardiac surgery, or may persist for months to years. Atrial flutter is generally classified into three types common, uncommon, and atypical impure or type 2 atrial flutter. Common...
Acquired Lqts
The explosion in knowledge regarding the ionic mechanisms of the congenital LQTS has also generated new insights into the pathogenesis of various forms of acquired LQTS. It is now clear that many of the drugs that precipitate acquired LQTS are potent blockers of IKr HERG , the same protein that is mutated in patients with the LQT2 form of congenital LQTS 46 . Most cases of acquired LQTS occur in patients with no identifiable ion-channel mutations, although there have been occasional reports of...
Info Snh
Fig. 23. This patient with anterolateral MI developed RBBB and LPFB. A temporary pacemaker was placed. Because of intermittent second-degree A-V block, a permanent pacemaker was implanted. Fig. 24. This 75-yr-old male with anteroseptal MI developed RBBB, LAFB, and first-degree A-V block so-called trifascicular block. Because the patient had received thrombolytic therapy, transcutaneous pacing pads were placed. No pacing was required over the next 72 h. Sustained monomorphic VT occurred 5 d...
Bradycardia Detection And Therapy
All currently available ICDs provide basic single-chamber ventricular VVI pacing with separate programmable post-shock lower rate limit and output. Recently, dual-chamber devices have been introduced with use of an atrial lead for diagnostic use only or for atrioventricular AV synchronized pacing. These devices allow multiple programmable pacing modes including DDDR, DDD, DDIR, DDI, AAIR, AAI, VVIR, and VVI. These expanded pacing modes have obviated the need for a separate dual-chamber...
General Principles Of Antiarrhythmic Therapy
Steps in the Selection of Antiarrhythmic Therapy Thorough evaluation of the individual patient and the clinical context is the essential first step in the selection of the optimal treatment strategy. This includes a determination of the underlying cardiac disorder and its severity, comorbid conditions, response to previous therapy, and other factors that affect prognosis and the response to various treatment alternatives. The second step includes risk assessment for each mode of death...
Vt Related To Regions Of Scar
The most common cause of VT is reentry through regions of scar, most commonly an old MI Fig. 4 . Other scar-related VTs occur because of arrhythmogenic right ventricular dysplasia, sarcoidosis, Chagas' disease, and other nonischemic cardiomyopathies. Two features of ventricular scarring lead to reentrant VT 40-42 . First, dense scarring creates regions of anatomic conduction block. Second, the scar is not comprised completely of dense fibrotic tissue, but also contains surviving myocyte bundles...
References Sle
1. Gregoratos G, for the Task Force on Practice Guidelines Committee on Pacemaker Implantation of the American College of Cardiology American Heart Association. ACC AHA guidelines for implantation of cardiac pacemakers and antiarrhythmia devices. J Am Coll Cardiol 1998 31 1175-209. 2. Bernstein AD, Parsonnet V. Survey of cardiac pacing in the United States in 1989. Am J Cardiol 1992 69 331-338. 3. Buckingham TA, Volgman AS, Wimer E. Trends in pacemaker use results of a multicenter registry....
Internal Atrial Defibrillators
The success and safety of using low-energy internal cardioversion for AF led to the development of the implantable atrial defibrillator IAD . The IAD could operate automatically in a manner similar to a ventricular defibrillator, but since AF is rarely an emergency, cardioversion could be delayed for hours, allowing for spontaneous termination of AF, an attempt at pharmacological conversion, and or patient sedation. The typical candidate for an IAD is a patient with persistent and symptomatic...
K
Fig. 3. Continued Examples of NSVT K 12-Lead ECG in a patient with repetitive, nonsustained idiopathic VT of right ventricular outflow tract RVOT origin. Note the characteristic LBBB, normal-axis morphology. Fig. 3. Continued Examples of NSVT K 12-Lead ECG in a patient with repetitive, nonsustained idiopathic VT of right ventricular outflow tract RVOT origin. Note the characteristic LBBB, normal-axis morphology. indicate either multiple discrete circuits or multiple breakthrough sites from the...
Accessory Pathways
Accessory pathways are anomalous extranodal tissues that connect the epicardial surface of the atrium and ventricle along the atrioventricular groove. Accessory pathways can be classified based on their location along the mitral or tricuspid annulus, type of conduction decremental or nondecremental , and whether they are capable of antegrade conduction, retrograde conduction, or both. Accessory pathways that conduct only retrogradely are termed concealed since they do not cause ventricular...
Magnet Function
Confusion abounds concerning the function of a magnet with ICDs. The pulse generator contains a reed switch that is closed when a magnet is placed over the device. Closure of the reed switch prevents delivery of tachyarrhythmia therapy. Unlike pacemakers, bradycardia pacing is not affected by the use of a magnet in ICDs. Normal device therapy resumes when the magnet is removed and the reed switch opens. One manufacturer, Cardiac Pacemakers, Inc. Guidant, has developed two expanded functions...
Peter Gallagher MD and J Marcus Wharton MD
AV-Nodal Modification and Ablation Adjunctive Atrial Pacing Direct Current Cardioversion Internal Atrial Defibrillators Surgical Therapy of AF Catheter Ablation of Atrial Fibrillation Hybrid Approaches References The prevalence of atrial fibrillation AF 1 has risen as the population of individuals over 60 years old has increased, fostering a growing need to develop better and more cost-effective means of controlling and preventing AF. Although pharmacological rate control, suppression of...
Info Ler
Fig. 2. Monomorphic VT in a patient with prior MI. A The initial rate of VT was 163 BPM. B Following a procainamide load, the VT has slowed to 118 BPM, and the QRS has widened. Fig. 2. Monomorphic VT in a patient with prior MI. A The initial rate of VT was 163 BPM. B Following a procainamide load, the VT has slowed to 118 BPM, and the QRS has widened. patients had previous MI, and many had incessant VT or were receiving cardiopulmonary resuscitation CPR . Both studies demonstrated a...
A
Fig. 1. ECGs in three patients with atrial tachycardia. A Atrial activity is most prominent in lead Vi. Note that the P wave is closer to the next QRS complex than the previous QRS complex a so-called long-RP tachycardia. There is 1 1 conduction until the end of the tracing, when AV nodal block reveals low amplitude P waves. B Atrial tachycardia with 2 1 A V conduction, and left bundle-branch block LBBB aberrancy in a patient with dilated cardiomyopathy. P-wave activity is most evident in lead...
Info Ouc
MADIT Multicenter Automatic Defibrillator Implantation Trial CABG Patch Coronary Artery Bypass Graft Patch trial MUSTT Multicenter Unsustained Tachycardia Trial SCD HeFT Sudden Cardiac Death in Heart Failure Trial MADIT II Multicenter Automatic Defibrillator Implantation Trial-II MI myocardial infarction CMP cardiomyopathy ICD implantable cardioverter defibrillator EPS electrophysiology study SAECG signal-averaged electrocardiogram LV left ventricle. MADIT Multicenter Automatic Defibrillator...