Explore the vast range of titles available.

The fusion of narrow‐QRS sinus‐generated beats with end‐diastolic ventricular extrasystoles occurring in bigeminy can produce an electrocardiographic pattern difficult to differentiate from parasystole. Such an ECG should not be interpreted as 2:1 RBBB because of the variability of the PR intervals.

This report describes a patient who underwent cardiac resynchronization complicated by a Twiddler syndrome. This caused triple atrial sensing and an inappropriate shock.This report describes a patient who underwent cardiac resynchronization complicated by a Twiddler syndrome. This caused triple atrial sensing and an inappropriate shock.

Mobitz type II second-degree atrioventricular block (AVB) is an electrocardiographic pattern that describes what appears to be an all-or-none conduction without visible changes in the AV conduction time or PR intervals before and after a single non-conducted P wave. An unchanged PR interval after the block is a sine qua non of Mobitz type II block. A 2:1 AVB cannot be classified in terms of type I or type II AVB. The diagnosis of Mobitz type II block AVB requires a stable sinus rate, which is an important criterion because a vagal surge (generally benign) can cause simultaneous sinus slowing and AV nodal block, which can resemble Mobitz type II AVB. Atypical forms of Wenckebach AVB may be misinterpreted as Mobitz type II AVB when a series of PR intervals are constant before the block. Concealed His bundle or ventricular extrasystoles may mimic both Wenckebach and/or type II AVB (pseudo-AVB). Correctly identified Mobitz type II AVB is invariably at the level of the His–Purkinje system and is an indication for a pacemaker.

This brand new guide assists students, interns and residents in developing a functional understanding of the set-up, workings and interpretation of ECGs * Step-by-step graphics and short, bite-sized explanations * Covers all major cardiac abnormalities including hypertrophy, arrhythmias, conduction blocks, and pre-excitation syndromes * Begins with a section on physiology of the heart and the basic set up of ECG recording * Features top tips on what to look for, complete with illustrated examples * Supported by a companion website featuring additional practice tracings

Non-left bundle branch block (non-LBBB) remains an uncertain indication for cardiac resynchronization therapy (CRT). Non-LBBB includes right bundle branch block (RBBB) and non-specific LV conduction delay (NSCD), two different electrocardiogram (ECG) patterns which are not generally considered to be associated with LV conduction delay as judged by the invasive assessment of the Q-LV interval. We evaluated whether a novel ECG interval (QR-max index) correlated with the degree of LV conduction delay regardless of the type of non-LBBB ECG pattern, and could, therefore, predict CRT response. In 173 non-LBBB patients on CRT (92 NSCD, 81 RBBB), the QR-max index was measured as the maximum interval from QRS onset to R-wave offset in the limb leads. The correlation between QR-max index and Q-LV interval and the impact of the QR-max index on time to first heart failure hospitalization during 3-year follow-up were assessed. Q-LV correlated better with the QR-max index than with QRSd, particularly in the RBBB group (r = 0.91; p < 0.001 vs. r = 0.19; p < 0.089), while the correlations were r = 0.79 (p < 0.01) and r = 0.68 (p < 0.01), respectively, in the NSCD group. In both groups, the QR-max index was significantly more able than QRSd to identify CRT responders (AUC 0.825 vs. 0.576; p = 0.0008 in RBBB; AUC 0.738 vs. 0.701; p = 0.459 in NSCD). A QR-max index exceeding a cutoff value of 120 ms was associated with CRT response, with predictive values of 86.8 and 81.4% in RBBB and NSCD, respectively. The QR-max index reflects the degree of LV electrical delay regardless of QRS duration in RBBB and NSCD patients and is a useful indicator of suitability for CRT in non-LBBB patients.

This report describes the occurrence of asymptomatic hyperkalemia induced by the sequential administration of metoprolol and carvedilol in an 81-year-old man with type II diabetes and stable stage III renal insufficiency. The potassium level rose to 5.6–5.7 mEq/L with metoprolol and normalized when the agent was discontinued. However, the potassium level rose again to 5.6 mEq/L after the administration of carvedilol but the level normalized by halving the dose. The observations of hyperkalemia induced by two different β-blocker drugs in the same patient confirm that this side effect is common to all β-blocker drugs.

While bringing into focus the major advances in cardiac pacing over the last 5-6 years this book places particular emphasis on new techniques for the treatment of congestive heart failure. Other topics include new and unusual indications for pacemakers, the clinical aspects of expanding pacemaker memory and stored electrograms in the diagnosis of arrhythmias, automatic mode switching, the pacemaker/ICD interface, complex pacemaker electrocardiography and advances in pacemaker follow-up. This book will be a valuable resource for those involved in the care of patients with implanted devices.

This new edition of the bestselling step-by-step introduction to cardiac pacemakers now includes additional material on CRT and an accompanying website. It retains the effective use of full-page illustrations and short explanations that gained the book such enormous popularity and now provides information on recent advances in cardiac pacing, including biventricular pacing for the treatment of heart failure.

Ventriculoatrial (VA) synchrony during dual chamber pacing can occur in any patient who has the ability to sustain repeated retrograde conduction. If the retrograde P wave is sensed, the result will be an endless loop tachycardia or repetitive reentrant VA synchrony. VA synchrony can also occur when a dual chamber pacemaker does not sense a retrograde P wave within the postventricular atrial refractory period. In this situation if the normally suprathreshold atrial stimulus at the end of the atrial escape interval is continually delivered when the atrial myocardium is physiologically refractory, the result will be a repetitive nonreentrant VA synchronous rhythm. Repetitive nonreentrant VA synchrony may produce unfavorable hemodynamic consequences and the pacemaker syndrome. It represents an example of functional atrial undersensing combined with functional loss of atrial capture. Management requires modification of the programmed settings of the pacemaker and utilization of certain algorithms designed for other functions but nevertheless effective in this situation.