ECG criteria to distinguish between aberrantly conducted supraventricular tachycardia and ventricular tachycardia: practical aspects for the immediate care setting

A case report reappraising the usefulness of Valsalva manoeuvre in drug-refractory ventricular tachycardia

BACKGROUND

Ventricular tachycardia (VT) is often misdiagnosed as supraventricular tachycardia with aberrancy. Twelve-lead electrocardiogram remains a key diagnostic tool to differentiate them while providing insights to aid localization of VT. The use of Valsalva manoeuvre (VM) in terminating VT is not conventionally recommended due to lack of robust evidence of its effectiveness and poor understanding of its mechanism in terminating VT.

CASE SUMMARY

A 74-year-old man with history of ischaemic heart disease was admitted with broad complex tachycardia. VT-1 was diagnosed following failed tachycardia termination by adenosine. Haemodynamic compromise necessitated synchronized cardioversion with successful reversion. However, a different VT-2 occurred after cardioversion. VM led to successful termination of VT-2. Subsequently, recurrent episodes of VT-2 occurred with consistent termination by VM. Transthoracic echocardiogram, cardiac magnetic resonance imaging, and a coronary angiogram were performed. Findings suggested that these are likely scar-related VT. VT-1 originated from an anteroseptal scar, whilst VT-2, responsive to VM, likely originated from the Purkinje fibres. Patient remained eurhythmic after Day 1 following amiodarone and beta-blocker initiation. An implantable cardioverter-defibrillator was implanted prior to discharge.

DISCUSSION

VM is one of the vagal manoeuvres which are commonly used as initial management of supraventricular tachycardia. Its role in management of VT is obscure. Anecdotal case series recorded its successful use for managing particular VT. Exact mechanism remains elusive although postulated to involve change in cardiac size during strain and release of acetylcholine.

Electrical storm: A focused review for the emergency physician

BACKGROUND

Electrical storm is a dangerous condition presenting to the Emergency Department that requires rapid diagnosis and management.

OBJECTIVE

This article provides a review of the diagnosis and management of electrical storm for the emergency clinician.

DISCUSSION

Electrical storm is defined as ≥3 episodes of sustained ventricular tachycardia, ventricular fibrillation, or shocks from an implantable cardioverter defibrillator within 24 h. Patients may present with a wide array of symptoms. Initial evaluation should include an electrocardiogram with a rhythm strip and continuous cardiac monitoring, a medication history, assessment of hemodynamic stability, and identification of potential triggers. Management includes an antiarrhythmic and a beta blocker. Refractory patients may benefit from double-sequential defibrillation or more invasive procedures such as intra-aortic balloon pumps, catheter ablation and extracorporeal membrane oxygenation for critically ill patients. These patients will typically require admission to an intensive care unit.

CONCLUSION

Electrical storm is a condition associated with significant morbidity and mortality. It is important for clinicians to be aware of the current evidence regarding the evaluation and management of these patients.

New ECG criteria for differential diagnosis of wide QRS complex tachycardias with right bundle branch block pattern

AIM

To evaluate standard 12-lead ECG indices for the differential diagnosis of wide QRS tachycardias with right bundle branch block (RBBB) pattern.

MATERIALS AND METHODS

Study analyses the 244 ECG indices in 111 patients (79 males and 32 females, age 53±17 years) with RBBB tachycardias, who underwent electrophysiological studies. First step includes retrospective analysis of QRS characteristics in 20 patients with ventricular tachycardias (VT), 24 pts with aberrant supraventricular tachycardias (SVT+RBBB) and 14 pts with antidromic SVTs (WPW). ROC- and multifactorial analyses were performed to develop diagnostic ECG algorithms. The prognostic accuracy of the algorithms was subsequently evaluated on a prospective group of patients with RBBB tachycardias (n=53).

RESULTS

ECG criteria of RBBB VTs were: 1) the presence Q-wave in lead II, 2) the duration interval R(peak)-S(end) >100 ms in lead V5. ECG criteria for antidromic SVTs with RBBB were: 1) the duration of the R wave in lead I ≥80 ms, 2) the absence of split (M-sharp) R-waves in lead V2, 3) the absence notch in ascending S wave in lead aVL. The accuracy of the algorhythm for diagnostic of VTs with RBBB was 83% (sensitivity 100%, specificity 73%). The accuracy of the algorhythm for diagnostic of antidromic SVTs with RBBB was 91% (sensitivity 85%, specificity 96%).

CONCLUSION

The proposed algorithms are based on new ECG criteria for the differential diagnosis of wide QRS complexes tachycardias with RBBB pattern, unlike the previous algorithms.

[Automatic detection of ventricular and supraventricular wide QRS arrhythmias using complex of morphological criteria and algorithms]

AIM

The aim of study is a detection of ventricular and supraventricular wide QRS arrhythmias using complex of morphological criteria and algorithms by method of automatic analysis.

MATERIALS AND METHODS

For 100 patients (m/f - 61/39, Me (min; max) - 44.5 (10; 85) years) of researched group the analysis of 14306 single wide ectopic complexes (QRS 120-230 ms) has been done. Wide complexes include 11028 (77%) ventricular complexes and 3278 (23%) supraventricular complexes represented by 145 different forms of QRS. For verification of arrhythmias origin transesophageal ECG recording and endocardial electrophysiological study were done. The control group included 59 patients (m/f - 25/34, Me (min; max) - 49.5 (14,85) years) with 720 wide QRS, including 467 (65%) ventricular and 253 (35%) supraventricular complexes represented by 86 forms of QRS. The criteria Drew B.J., Scheinman M.M. (1995); Wellens H.J. (1978), RWPT II (Pava LF, 2010) and the algorithms of Brugada P. (1991); Bayesian (2000); Vereckei A. (2008) were used to evaluate sensitivity, specificity and diagnostic accuracy of wide QRS complexes recognition one by one and together, using the method of Wald sequential automatic analysis (KT Result3, CJSC INCART, Russia) and method of artificial neural networks.

RESULTS

The best results for the detection of ventricular arrhythmias algorithms were demonstrated by the  Brugada  P., Drew  B.J., Scheinman  M.M. algorithm (sensitivity 86.43%, specificity 66.73%, diagnostic accuracy 82.14% in the study group, sensitivity 81.80%, specificity 73.12%, diagnostic accuracy 78.75% in the control group), and the Bayesian algorithm (sensitivity 87.81%, specificity 73.62%, diagnostic accuracy 84.72% in the study group, sensitivity 83.30%, specificity 77.08%, diagnostic accuracy 81.11% in the control group). A complex analysis of the Wald method recognized ventricular arrhythmias in the research group with sensitivity 83.11%, specificity 83.65%, diagnostic accuracy 83.23% and in the control group with a sensitivity 83.51%, specificity of 84.58% and diagnostic accuracy 83.89%. Artificial neural networks recognized ventricular arrhythmias with sensitivity 91.43%, specificity 91.30% and diagnostic accuracy 91.39% in the control group and with sensitivity 97.06%, specificity 99.39% and diagnostic accuracy 97.6% in the research group.

CONCLUSION

Automatic analysis allows obtaining simultaneously the results of each algorithms/criteria and in combination. It significantly reduces the doctor's work in assessing of amplitude-time characteristics of the complexes. Using artificial neural networks increases the accuracy of of ventricular and supraventricular arrhythmias recognition.

The Value of Detecting Asymptomatic Signs of Myocardial Ischemia in Patients With Coronary Artery Disease in Outpatient Cardiac Rehabilitation

BACKGROUND

Electrocardiographic (ECG) monitored outpatient cardiac rehabilitation (OP-CR) is routinely performed following a variety of cardiovascular procedures and conditions.

OBJECTIVE

The aim of this study is to determine if diagnostic-quality ECG monitoring in patients with coronary artery disease (CAD) during OP-CR is useful in identifying asymptomatic myocardial ischemia, resulting in change(s) in care or medical management.

METHODS

A retrospective analysis of ECG monitoring was done on all OP-CR patients diagnosed with CAD (n = 1213) from January 2000 through June 2013.

RESULTS

Nearly a quarter of the patients (24%; n = 288) displayed at least 1 mm of asymptomatic ST-segment depression at 80 milliseconds after the J-point during at least 1 session of OP-CR. Of these patients, 57% had medical management change(s) compared with 24% for those who did not show ECG changes suggesting ischemia (P < .0001). In patients with asymptomatic ischemia having medical management change(s), 84% resulted directly from OP-CR staff detection. Fewer patients diagnosed with myocardial infarction and coronary artery bypass graft surgery demonstrated ECG signs of ischemia, whereas more patients diagnosed with stable angina and percutaneous coronary interventions demonstrated ECG signs of ischemia.

CONCLUSION

This study demonstrates that most patients with CAD showing asymptomatic ECG signs suggesting ischemia undergo medical management change(s) as a result of the finding. Diagnostic-quality ECG monitoring during OP-CR appears warranted in this population.

Wide Complex Tachycardia - Ventricular Tachycardia or Not Ventricular Tachycardia, That Remains the Question

Arriving at the correct diagnosis in cases of wide complex tachycardia remains problematic for many clinicians. In this paper, we review the historical development of criteria used to differentiate among the major diagnostic possibilities and compare the strengths and weaknesses of various differentiating algorithms.

The value of electrocardiography for differential diagnosis in wide QRS complex tachycardia

Correct diagnosis in wide QRS complex tachycardia remains a challenge. Differential diagnosis between ventricular and supraventricular tachycardia has important therapeutic and prognostic implications, and although data from clinical history and physical examination may suggest a particular origin, it is the 12-lead surface electrocardiogram that usually enables this differentiation. Since 1978, various electrocardiographic criteria have been proposed for the differential diagnosis of wide complex tachycardias, particularly the presence of atrioventricular dissociation, and the axis, duration and morphology of QRS complexes. Despite the wide variety of criteria, diagnosis is still often difficult, and errors can have serious consequences. To reduce such errors, several differential diagnosis algorithms have been proposed since 1991. However, in a small percentage of wide QRS tachycardias the diagnosis remains uncertain and in these the wisest decision is to treat them as ventricular tachycardias. The authors' objective was to review the main electrocardiographic criteria and differential diagnosis algorithms of wide QRS tachycardia.

Comparison of the "real-life" diagnostic value of two recently published electrocardiogram methods for the differential diagnosis of wide QRS complex tachycardias

OBJECTIVES

The diagnostic values of the aVR lead or "Vereckei algorithm," and the lead II R-wave peak time (RWPT) criterion, recently devised for the differential diagnosis of wide QRS complex tachycardias (WCTs), were compared.

METHODS

A total of 212 WCTs (142 ventricular tachycardias [VTs], 62 supraventricular tachycardias [SVT], and eight preexcitation SVTs) from 145 patients with proven electrophysiologic diagnoses were retrospectively analyzed by seven examiners blinded to the electrophysiologic diagnoses.

RESULTS

The overall test accuracy of the Vereckei algorithm was superior to that of the RWPT criterion (84.3% vs. 79.6%; p = 0.0003). The sensitivity of the Vereckei algorithm for VT diagnosis was greater than that of RWPT criterion (92.4% vs. 79.1%; p < 0.0001). The negative predictive value (NPV) for the Vereckei algorithm was also greater (77.8%; 95% confidence interval [CI] = 73.6% to 82.1%) than that of the RWPT criterion (61.6%; 95% CI = 57.6% to 65.6%). The specificity of the Vereckei algorithm was lower than that of the RWPT criterion (64.7% vs. 80.9%; p < 0.0001). The positive predictive value (PPV) was also lower for the Vereckei algorithm (86.4%; 95% CI = 84.4% to 88.4%) than for the RWPT criterion (90.9%; 95% CI = 89.1% to 92.8%). Incorrect diagnoses made by the Vereckei algorithm were mainly due to misdiagnosis of SVT as VT (65.7% of cases), and those made by the RWPT criterion were due to the more dangerous misdiagnosis of VT as SVT (72.5% of cases).

CONCLUSIONS

The Vereckei algorithm was superior in overall test accuracy, sensitivity, and NPV for VT diagnosis and inferior in specificity and PPV to the RWPT criterion. All of these parameters were lower in "real life" than those reported by the original authors for each of the particular electrocardiographic methods.

Electrocardiographic artefacts mimicking atrial tachycardia resulted in unnecessary diagnostic and therapeutic measures

Electrocardiographic (ECG) artefacts may closely simulate both supraventricular and ventricular tachycardias. We describe a case initially diagnosed as rapid atrial fibrillation, based on 12-lead surface ECG (especially the limb leads) and monitor tracing. The arrhythmia was resistant to beta blockers. Because of the at times apparently regular rhythm, an esophageal ECG recording was performed, and adenosine was administered. When the presumed atrial fibrillation terminated after sodium pentothal was administered while preparing for electrical cardioversion, the oesophageal ECG recordings and the ECGs during adenosine administration were reviewed. An ECG artefact diagnosis was suspected, and then confirmed, during relapse of the "arrhythmia," with simple palpation of the radial pulse and cardiac auscultation.

Rhythm disturbances

Patients with cardiac rhythm disturbances may present in a variety of conditions. Patients may be unstable, requiring immediate interventions, or stable, allowing for a more deliberate approach. Rapid assessment of patient stability, underlying rhythm, and determination of appropriate interventions guides timely therapy. This article discusses the differential diagnosis and treatment of adult patients presenting with primary bradyarrhythmias and tachyarrhythmias, with the exception of atrial fibrillation and atrial flutter, covered elsewhere in this issue. A concise approach to diagnosis and determination of appropriate therapy is presented.

Applying evidence at the bedside: a journey to excellence in bedside cardiac monitoring

Bedside cardiac monitoring is a nursing domain, and lead selection is determined by the monitoring needs of the patient. Understanding the rationale behind the evidence empowers the bedside critical-care nurse to make monitoring decisions that best meet the monitoring needs of the patient. This article discusses a journey to move beyond the sacred cows of monitoring and utilize the available literature to make monitoring choices that best meet the needs of each individual patient.

Asymptomatic wide complex tachycardia: a case report

Wide complex tachycardias are a commonly encountered entity in coronary care units, intensive care units and emergency departments. Though, these arrhythmias are potentially fatal, they need to recognized first and treated appropriately. Associated physical signs are helpful in this. We present a case of a 54-year-old-female who recently underwent placement of an implantable cardioverter-defibrillator for cardiomyopathy and developed tachycardia.

Life-threatening arrhythmias in the intensive care unit

Symptomatic arrhythmias are frequently observed in the intensive care unit and often lead to significant hemodynamic compromise because of the presence of multisystem disease. In particular, prompt evaluation of patients with tachycardia is critical because treatment depends on the accurate diagnosis of the arrhythmia mechanism. The electrocardiogram remains the most important diagnostic tool for the evaluation of both wide complex and narrow complex tachycardia. For wide complex tachycardia, evaluation of the atrioventricular relationship and QRS morphology are critical, and for narrow QRS complex tachycardias, evaluation focuses on identification of the location and morphology of P waves. Bradycardia can arise from sinus node dysfunction or atrioventricular conduction block.

Practice standards for ECG monitoring in hospital settings: executive summary and guide for implementation

Current goals of hospital ECG monitoring are to diagnose cardiac arrhythmias, acute myocardial ischemia, and drug-induced prolonged QT interval. Recently, experts in the field of electrocardiology and cardiac monitoring convened to develop a practice standard for hospital ECG monitoring. This executive summary reviews key elements of the practice standard and answers questions that often arise when clinicians try to implement them.

Tachydysrhythmias

Tachydysrhythmias arise from different mechanisms that can be characterized as being caused by re-entrant circuits, enhanced or abnormal automaticity, or triggered after-depolarizations. The approach to the tachydysrhythmia should begin with distinguishing sinus from non-sinus rhythms, then assessing QRS complex width and regularity. This article review tachydysrhythmias.

Blood oxygen saturation during atrio-ventricular dissociation with wide-QRS complex tachycardias

Amplitude ratios of two adjacent mixed blood oxygen saturation curve peaks in randomly selected strips of ECG were analysed in 32 patients with regular wide-QRS complex tachycardias and 60 control subjects where pacing was performed before ablation of narrow-QRS complex tachycardias. Patients with VT showed different patterns of A-to-V relationships, leading to varying ratios of SpO2 adjacent peak amplitudes, in contrast to patients with aberrant SVTs and 1:1 AV association. Application of a criterion of adjacent SpO2 peaks differing by twofold or more had a sensitivity of 90.0% and specificity of 83.3% to detect AV dissociation during VT. Fluctuations on the mixed oxygen saturation curve may be a useful non-invasive clinical parameter to detect different ventricular filling caused by atrio-ventricular dissociation during VT.

AHA scientific statement: practice standards for electrocardiographic monitoring in hospital settings: an American Heart Association Scientific Statement from the Councils on Cardiovascular Nursing, Clinical Cardiology, and Cardiovascular Disease in the Young: endorsed by the International Society of Computerized electrocardiology and the American Association of Critical-Care Nurses

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas Computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals. Moreover, because no computerized analysis is available for QT monitoring, healthcare professionals must determine when it is appropriate to manually measure QT intervals (eg, when a patient is started on a potentially proarrhythmic drug). The purpose of the present review is to provide "best practices" for hospital ECG monitoring. Randomized clinical trials in this area are almost nonexistent; therefore, expert opinions are based upon clinical experience and related research in the field of electrocardiography. This consensus document encompasses all areas of hospital cardiac monitoring in both children and adults. The emphasis is on information clinicians need to know to monitor patients safely and effectively. Recommendations are made with regard to indications, time frames, and strategies to improve the diagnostic accuracy of cardiac arrhythmia, ischemia, and QT-interval monitoring. Currently available ECG lead systems are described, and recommendations related to staffing, training, and methods to improve quality are provided.

Practice Standards for Electrocardiographic Monitoring in Hospital Settings

The goals of electrocardiographic (ECG) monitoring in hospital settings have expanded from simple heart rate and basic rhythm determination to the diagnosis of complex arrhythmias, myocardial ischemia, and prolonged QT interval. Whereas computerized arrhythmia analysis is automatic in cardiac monitoring systems, computerized ST-segment ischemia analysis is available only in newer-generation monitors, and computerized QT-interval monitoring is currently unavailable. Even in hospitals with ST-monitoring capability, ischemia monitoring is vastly underutilized by healthcare professionals. Moreover, because no computerized analysis is available for QT monitoring, healthcare professionals must determine when it is appropriate to manually measure QT intervals (eg, when a patient is started on a potentially proarrhythmic drug). The purpose of the present review is to provide ‘best practices’ for hospital ECG monitoring. Randomized clinical trials in this area are almost nonexistent; therefore, expert opinions are based upon clinical experience and related research in the field of electrocardiography. This consensus document encompasses all areas of hospital cardiac monitoring in both children and adults. The emphasis is on information clinicians need to know to monitor patients safely and effectively. Recommendations are made with regard to indications, timeframes, and strategies to improve the diagnostic accuracy of cardiac arrhythmia, ischemia, and QT-interval monitoring. Currently available ECG lead systems are described, and recommendations related to staffing, training, and methods to improve quality are provided.

Frequency and characteristics of progressive aberrancy during supraventricular tachycardia

Progressive aberrancy (defined as beats with QRS duration and morphology between that of sinus rhythm and full aberrancy) occurred in 10 of 32 episodes of atrial pacing in 5 of 11 patients. The episodes resembled fusion beats but were due to bilateral bundle branch delay.

Celebrating the 100th Birthday of the Electrocardiogram: Lessons Learned From Research in Cardiac Monitoring

The electrocardiogram continues to be the gold standard for the diagnosis of cardiac arrhythmias and acute myocardial ischemia. The treatment of arrhythmias in critical care units has become less aggressive during the past decade because research indicates that antiarrhythmic agents can be proarrhythmic, causing malignant ventricular arrhythmias such as torsade de pointes. However, during the same period, the treatment of acute myocardial ischemia has become more aggressive, with the goal of preventing or interrupting myocardial infarction by using new antithrombotic and antiplatelet agents and percutaneous coronary interventions. For this reason, critical care nurses should learn how to use ST-segment monitoring to detect acute ischemia, which is often asymptomatic, in patients with acute coronary syndromes. Because the electrocardiographic lead must be facing the localized ischemic zone of the heart to depict the telltale signs of ST-segment deviation, the challenge is to find ways to monitor patients continuously for ischemia without using an excessive number of electrodes and lead wires. The current trend is to use reduced lead set configurations in which 5 or 6 electrodes, placed at convenient places on the chest, are used to construct a full 12-lead electrocardiogram. Nurse scientists at the University of California, San Francisco, School of Nursing are at the forefront in developing and assessing the diagnostic accuracy of these reduced lead set electrocardiograms.

The clinician's approach to evaluating patients with dysrhythmias

As cardiac arrhythmia services and the ability to perform electrophysiologic testing become more prevalent in the hospital setting, advanced practice nurses (APNs) are continually challenged to keep their skills in evaluating patients with dysrhythmias sharp and current. The experienced APN evaluates the patient's history, recognizes physical findings, and uses noninvasive data to help diagnose, anticipate, and even prevent dysrhythmias. This article reviews the essential components of a systematic evaluation of patients with a known or potential rhythm disturbance.

Electrocardiographic manifestations: aberrant ventricular conduction

Aberrant ventricular conduction is a common electrocardiographic (EKG) manifestation that occurs when the supraventricular electrical impulse is conducted abnormally through the ventricular conducting system. This results in a wide QRS complex that may be confused with a ventricular ectopic beat. This differentiation is important because the treatment and prognosis is quite different. Hemodynamically unstable patients with a wide-complex tachycardia should be promptly cardioverted. Although up to 10% of cases will defy differentiation, ventricular tachycardia and aberrant conduction can be distinguished utilizing history, physical examination, and EKG criteria. The mechanisms of aberrant ventricular conduction are discussed.

Accuracy of the EASI 12-lead electrocardiogram compared to the standard 12-lead electrocardiogram for diagnosing multiple cardiac abnormalities

This study was performed to compare a derived 12-lead electrocardiogram (ECG) using a simple 5-electrode lead configuration (EASI 12-lead) with the standard ECG for multiple cardiac diagnoses. Accurate diagnosis of arrhythmias and ischemia often require analysis of multiple (ideally, 12) ECG leads; however, continuous 12-lead monitoring is impractical in hospital settings. EASI and standard ECGs were compared in 540 patients, 426 of whom also had continuous 12-lead ST segment monitoring with both lead methods. Independent standards relative to a correct diagnosis were used whenever possible, for example, echocardiographic data for chamber enlargement-hypertrophy, and troponin levels for acute infarction. Percent agreement between the 2 methods were: cardiac rhythm, 100%; chamber enlargement-hypertrophy, 84%-99%; right and left bundle branch block, 95% and 97%, respectively; left anterior and posterior fascicular block, 97% and 99%, respectively; prior anterior and inferior infarction, 95% and 92%, respectively. There was very little variation between the 2 lead methods in cardiac interval measurements; however, there was more variation in P, QRS, and T-wave axes. Of the 426 patients with ST monitoring, 138 patients had a total of 238 ST events (26, acute infarction; 62, angioplasty-induced ischemia; 150, spontaneous transient ischemia). There was 100% agreement between the 2 methods for acute infarction, 95% agreement for angioplasty-induced ischemia, and 89% agreement for transient ischemia. EASI and standard 12-lead ECGs are comparable for multiple cardiac diagnoses; however, serial ECG changes (eg, T-wave changes) should be assessed using one consistent 12-lead method.

Evaluation of the specificity of morphological electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defects

BACKGROUND

Although several ECG criteria have been described for the differential diagnosis of tachycardias with a wide QRS complex, their applicability in patients with preexisting intraventricular conduction defects (IVCDs) has been questioned. The specificity of previously described criteria in this context is unknown.

METHODS AND RESULTS

We analyzed prospectively the specificity of the QRS morphological criteria previously described in ECGs during sinus rhythm of 232 patients with IVCD. Only 5 of 12 analyzed criteria had a specificity > or = 0.90 among our patients: (1) a triphasic configuration (Rsr' or Rr') QRS complex in V1 in the presence of a right bundle-branch block morphology (BBBM); (2) a QS, QR, or R QRS pattern in V6 in the presence of a right BBBM; (3) any Q in V6 in the presence of a left BBBM; (4) a concordant pattern in all precordial leads; and (5) the absence of an RS complex in all precordial leads (particularly useful for left BBBM). The following criteria--QRS duration > 140 ms; a left axis with right BBBM, right superior axis with right BBBM, monophasic or biphasic R wave in V1 with right BBBM, and a relation R/S < 1 with right BBBM; an R > 30 ms in lead V1 or V2 with left BBBM, > 60 ms from QRS onset to S nadir with left BBBM, a notched downstroke S wave with left BBBM, and an R-to-S interval > 100 ms in one precordial lead--had a specificity of 0.43, 0.54, 0.87, 0.80, 0.85, 0.78, 0.66, 0.69, and 0.63 (0.84 in right BBBM), respectively.

CONCLUSIONS

Most of the previously described morphological criteria favoring ventricular tachycardia are present in a substantial percentage of patients with IVCD during sinus rhythm. These findings suggest a limited applicability of these criteria in this subset of patients.

Cardiology

Emergency cardiac problems are a frequent and significant occurrence in the daily life of the emergency physician. The first part of this article discusses some of the pearls and pitfalls of caring for the cardiac patient ranging from treating wide-complex tachycardia and troubleshooting pacemaker malfunction to diagnosing acute myocardial infarction in the setting of bundle branch blocks. The second part of this article updates the reader on several of the newer technologies and treatments, such as transesophageal echocardiography and intravenous amiodarone, now in use in the emergency department setting.