Permanent junctional reciprocating tachycardia: a rare, but not to be missed, cause of cardiogenic shock in adults.

We report the case of a 64-year-old woman who was admitted for cardiogenic shock caused by a permanent junctional reciprocating tachycardia. If this incessant and drug-refractory form of tachycardia is a well-known cause of tachycardia-induced cardiomyopathies in infants, its occurrence during adulthood is extremely rare. Catheter ablation is the recommended treatment of this condition.

Slower heart rate and altered rate dependence of ventricular repolarization in patients with lone atrial fibrillation.

BACKGROUND: Electrophysiological alterations in atrial fibrillation (AF) may be genetically based and may lead to changes in ventricular repolarization. Short QT syndrome is a rare channelopathy with abbreviated ventricular repolarization and a propensity for AF. AIMS: To determine if minor unrecognized forms of short QT syndrome can explain some cases of lone AF. METHODS: We prospectively compared QT intervals in 66 patients with idiopathic lone AF and 132 age- and sex-matched controls. QT intervals were measured during sinus rhythm in each of the 12 surface electrocardiogram leads and corrected using Bazett's formula (QTc). QT intervals were also corrected using other formulae. Uncorrected QT and heart rate regression lines were compared between AF patients and controls. RESULTS: AF patients presented with a slower resting heart rate (64 ± 10 beats per minute [bpm] vs 69 ± 9 bpm; P=0.0006). QTc intervals were shorter in AF patients in 11/12 electrocardiogram leads (significant in 7/12, borderline in 2/12; mean QTc 381 ± 21 ms vs 388 ± 22 ms; P=0.02). QTc intervals were also shorter in AF patients, significantly or not, using other correction formulae. For similar heart rates, uncorrected QT intervals were shorter in patients when heart rates were greater than 70 bpm and longer when heart rates were less than 60 bpm. AF patients displayed steeper QT/heart rate regression line slopes than controls (P=0.009). CONCLUSION: Heart rate is significantly slower and the rate dependence of ventricular repolarization is significantly altered in patients with lone AF compared with controls. Further study is warranted to determine if AF induces subsequent ventricular repolarization changes or if these modifications are caused by an underlying primary electrical disease.

Incessant atrio-ventricular node reentrant tachycardia induced by unapparent dual atrio-ventricular node conduction.

We present the case of a patient with incessant slow-fast atrio-ventricular (AV) node reentrant tachycardia induced by dual AV node conduction with aborted conduction to the ventricles. The unapparent conduction over the slow pathway was suspected here because of spontaneous nodal echoes without QRS complexes occurring during sinus rhythm, manifested as isolated premature atrial beats and which repetitively induced the tachycardia.

Atrial oversensing by an LV lead during typical flutter: the interest of electronic repositioning.

Occurrence of supraventricular tachycardia is a common cause of clinical impairment for patients implanted with CRT devices. We report the case of atrial activity oversensing by the left ventricular (LV) lead during typical flutter, which led to LV pacing inhibition. Temporary reprogramming of the LV detection from standard bipolar to extended bipolar and cavotricuspid isthmus ablation solved this problem.

ST-segment changes after direct current external cardioversion for atrial fibrillation. Incidence, characteristics and predictive factors.

BACKGROUND: Incidence, characteristics and predictive factors of transient ST-segment changes after DC shock are poorly known. METHODS: 91 consecutive pts referred for external cardioversion of atrial fibrillation (AF) (61 men, 69±10 yo) were prospectively included. The presence of ST elevation or depression was assessed on 12 lead-ECG immediately after the first DC shock. Correlations with DC shock characteristics (monophasic/biphasic and energy), clinical variables, echocardiographic parameters, biological parameters, medications, anaesthetic drugs as well with morphological features were made. RESULTS: 18 and 20 pts underwent 200 J or 300 J monophasic and 53 pts 200 J biphasic DC shocks. We found an incidence of 48% for ST-segment changes: 35% for ST elevation and 13% for ST depression. ST changes did not induce significant cardiac events or alter AF recurrences. ST changes were not related to energy but ST elevation was significantly more often induced by monophasic (76% vs 6%, p<0.0001) and ST depression by biphasic DC shocks (26% vs 3%, p=0.01). Using multivariate analysis, independent predictors for ST elevation were the use of monophasic DC shocks, of propofol and increased CRP, while a low ejection fraction and use of biphasic DC shocks were independent predictors of ST depression. CONCLUSION: ST-segment changes after external cardioversion with DC shock are common, short living and do not carry clinical significance. They are related to the monophasic or biphasic configuration of DC shock, to the use of propofol, to the ejection fraction and to an increased CRP.

Variations in duration and composition of the excitable gap around the tricuspid annulus during typical atrial flutter.

BACKGROUND: Differences in the duration of the excitable gap along the reentry circuit during typical atrial flutter are poorly known. AIM: To prospectively evaluate and compare the duration and composition of the excitable gap during typical counterclockwise atrial flutter in different parts of the circuit all around the tricuspid annulus. METHODS: The excitable gap was determined by introducing a premature stimulus at various sites around the tricuspid annulus during typical counterclockwise atrial flutter in 34 patients. Excitable gap was calculated as the difference between the longest resetting coupling interval and the effective atrial refractory period. RESULTS: The duration of the excitable gap, the effective atrial refractory period and the resetting coupling interval differed significantly along the tricuspid annulus. Duration of excitable gap was significantly longer at the low lateral right atrium (79±22 ms) than at the cavotricuspid isthmus (66±23 ms; P=0.002). The effective atrial refractory period was significantly longer at the cavotricuspid isthmus (160±26 ms) than at the high lateral right atrium (149±29 ms; P=0.004). Other locations, such as coronary sinus ostium, right atrial septum and atrial roof displayed intermediate values. CONCLUSION: The duration of the excitable gap differed significantly along the tricuspid annulus, with a larger excitable gap at the lateral right atrium and a shorter excitable gap at the cavotricuspid isthmus, because of longer refractory periods at the isthmus.

Excessive sympathetic activation in heart failure with chronic renal failure: role of chemoreflex activation.

OBJECTIVE: Sympathetic activation contributes both to the initiation and progression of heart failure. The role of chronic renal failure (CRF) in determining sympathetic overactivity in chronic heart failure (CHF) patients is unknown. We tested the hypothesis that in CHF patients, CRF could lead to increase sympathetic activity through tonic activation of excitatory chemoreceptor afferents. METHODS: We conducted a double-blind, randomized, vehicle-controlled study to examine the effect of chemoreflex deactivation on muscle sympathetic nerve activity in CHF patients with or without CRF. We compared effect of breathing 100% oxygen for 15 min in 15 stable CHF patients with CRF and 15 control CHF patients matched for age, sex, blood pressure and BMI. RESULTS: The baseline muscle sympathetic nerve activity was significantly elevated in CHF patients with CRF as compared with simple CHF patients (61 +/- 3 versus 42 +/- 4 bursts/min; P < 0.01). Administration of 100% oxygen led to a significant decrease in muscle sympathetic nerve activity in CHF patients with CRF (from 61 +/- 3 to 55 +/- 4 bursts/min; P < 0.05). By contrast, neither 100% oxygen nor room air changed muscle sympathetic nerve activity or hemodynamics in patients with solely CHF. CONCLUSION: Tonic activation of excitatory chemoreflex afferents contributes to increased efferent sympathetic activity to muscle circulation and to blood pressure control in CHF patients with CRF. These findings may have important implications for understanding how CRF contributes to the progression of CHF and increases morbidity and mortality in CHF patients.