Regularly irregular atrial rhythm after superior vena cava isolation: Another manifestation of sinoatrial node injury?

The present case described an unusual clinical manifestation of the sinoatrial node (or sinoatrial junction) injury during superior vena cava isolation.

P-Wave Amplitude and PR Changes in Patients With Inappropriate Sinus Tachycardia: Findings Supportive of a Central Mechanism.

BACKGROUND: The mechanism of inappropriate sinus tachycardia (IST) remains incompletely understood. METHODS AND RESULTS: We prospectively compared 3 patient groups: 11 patients with IST (IST Group), 9 control patients administered isoproterenol (Isuprel Group), and 15 patients with cristae terminalis atrial tachycardia (AT Group). P-wave amplitude in lead II and PR interval were measured at a lower and higher heart rate (HR1 and HR2, respectively). P-wave amplitude increased significantly with the increase in HR in the IST Group (0.16±0.07 mV at HR1=97±12 beats per minute versus 0.21±0.08 mV at HR2=135±21 beats per minute, P=0.001). The average increase in P-wave amplitude in the IST Group was similar to the Isuprel Group (P=0.26). PR interval significantly shortened with the increases in HR in the IST Group (146±15 ms at HR1 versus 128±16 ms at HR2, P<0.001). A similar decrease in the PR interval was noted in the Isuprel Group (P=0.6). In contrast, patients in the atrial tachycardia Group experienced PR lengthening during atrial tachycardia when compared with baseline normal sinus rhythm (153±25 ms at HR1=78±17 beats per minute versus 179±29 ms at HR2=140±28 beats per minute, P<0.01). CONCLUSIONS: We have shown that HR increases in patients with IST were associated with an increase in P-wave amplitude in lead II and PR shortening similar to what is seen in healthy controls following isoproterenol infusion. The increase in P-wave amplitude and absence of PR lengthening in IST support an extrinsic mechanism consistent with a state of sympatho-excitation with cephalic shift in sinus node activation and enhanced atrioventricular nodal conduction.

Prevalence and predictors of low voltage zones in the left atrium in patients with atrial fibrillation.

Aims: To describe the extent and distribution of low voltage zones (LVZ) in a large cohort of patients undergoing ablation for paroxysmal and persistent atrial fibrillation (AF), and to explore baseline predictors of LVZ in these patients. Methods and results: Consecutive patients who underwent a bipolar voltage map guided AF ablation, were enrolled. Voltage maps were conducted for each patient using 3-dimensional electroanatomical mapping system and LVZ were defined as areas of bipolar voltage < 0.5 mV. A total of 539 patients (309 male, age 65 ± 10 years) were included. Low voltage zones was present in 58 out of 292 patients with paroxysmal and 134 out of 247 persistent AF (P < 0.001). The area of LVZ was larger in patients with persistent as compare to paroxysmal AF, 5 cm2 (IQR 3-18.6) vs. 12.1 cm2 (IQR 3.6-28.5), P = 0.026, respectively. In the multivariate analysis age (OR 1.07, 95%CI 1.05-1.10, P < 0.001), female gender (OR 2.18, 95%CI 1.38-3.43, P = 0.001), sinoatrial node dysfunction (OR 3.90, 95%CI 1.24-12.21, P = 0.020), larger surface area of left atrium pr. cm2 (OR 1.01, 95%CI 1.00-1.02, P = 0.016), and persistent AF (OR 5.03, 95%CI 3.20-7.90, P<0.001) were associated with presence of LVZ. Conclusion: In a large cohort of patients undergoing ablation for AF, the prevalence of LVZ was higher and LVZ areas larger in patients with persistent as compared with paroxysmal AF. The most frequent localization of LVZ was anterior wall, septum and posterior wall. Presence of LVZ was associated with higher age, female gender, larger LA surface area, and sinoatrial node dysfunction.

Comparative Assessment of the Heart's Functioning by Using the Akabane Test and Classical Methods of Instrumental Examination.

Acupuncture physicians have studied the application of reflexotherapy to cardiology. However, no one has investigated the connection of ancient Chinese diagnostic methods with modern tools. A total of 102 patients (54 men and 48 women) with heart pathology, namely, sick-sinus syndrome, Wolff-Parkinson-White syndrome, and atrioventricular blockade, were studied using the usual instrumental methods (transesophageal electrophysiological study of the heart, echocardiography), after which they underwent Akabane thermopuncture testing as in traditional Chinese medicine. The results of cardio examination from one side of the Akabane test with that from the other side were compared by means of a multiple stepwise regression analysis. We revealed the effects on the characteristic pattern of acupuncture channel lesions inherent in a definite heart pathology, i.e., the most vulnerable acupuncture channel (AC), of such factors as disturbances of the contractile, conductive, or automatic heart functions, and changes in the chambers' size or circulation volume. Сhanges in the indices of the left and the right branches of these channels usually reflect the opposing natures of the changes in these indicators, which should be considered in reflexotherapy. The main value of the Akabane test along with the use of mathematical analysis lies in early, quick, and inexpensive detection of the above-mentioned heart disturbances.

Prolonged Sinus Pauses upon Termination of Paroxysmal Atrial Fibrillation: Abnormal Right Atrial Electrophysiologic and Electroanatomic Findings.

The efficacy of pulmonary vein antral isolation for patients with prolonged sinus pauses (PSP) on termination of atrial fibrillation has been reported. We studied the right atrial (RA) electrophysiologic and electroanatomic characteristics in such patients. Forty patients underwent electroanatomic mapping of the RA: 13 had PSP (group A), 13 had no PSP (group B), and 14 had paroxysmal supraventricular tachycardia (control group C). Group A had longer P-wave durations in lead II than did groups B and C (115.5 ± 15.4 vs 99.5 ± 10.9 vs 96.5 ± 10.4 ms; P=0.001), and RA activation times (106.8 ± 13.8 vs 99 ± 8.7 vs 94.5 ± 9.1 s; P=0.02). Group A's PP intervals were longer during adenosine triphosphate testing before ablation (4.6 ± 2.3 vs 1.7 ± 0.6 vs 1.5 ± 1 s; P <0.001) and after ablation (4.7 ± 2.5 vs 2.2 ± 1.4 vs 1.6 ± 0.8 s; P <0.001), and group A had more complex electrograms (11.4% ± 5.4% vs 9.3% ± 1.6% vs 5.8% ± 1.6%; P <0.001). Compared with group C, group A had significantly longer corrected sinus node recovery times at a 400-ms pacing cycle length after ablation, larger RA volumes (100.1 ± 23.1 vs 83 ± 22.1 mL; P=0.04), and lower conduction velocities in the high posterior (0.87 ± 0.13 vs 1.02 ± 0.21 mm/ms; P=0.02) and high lateral RA (0.89 ± 0.2 vs 1.1 ± 0.35 mm/ms; P=0.04). We found that patients with PSP upon termination of atrial fibrillation have RA electrophysiologic and electroanatomic abnormalities that warrant post-ablation monitoring.

Ablation of Inappropriate Sinus Tachycardia: A Systematic Review of the Literature.

OBJECTIVES: The goal of this study was to describe short- and long-term outcomes in all patients referred for inappropriate sinus tachycardia ablation, along with the potential complications of the intervention. BACKGROUND: Sinus node (SN) ablation/modification has been proposed for patients refractory to pharmacological therapy. However, available data derive from limited series. METHODS: The electronic databases MEDLINE, Embase, CINAHL, Cochrane, and Scopus were systematically searched (January 1, 1995-December 31, 2015). Studies were screened according to predefined inclusion and exclusion criteria. RESULTS: A total of 153 patients were included. Their mean age was 35.18 ± 10.02 years, and 139 (90.8%) were female. All patients had failed to respond to maximum tolerated doses of pharmacological therapy (3.5 ± 2.4 drugs). Mean baseline heart rates averaged 101.3 ± 16.4 beats/min according to electrocardiography and 104.5 ± 13.5 beats/min according to 24-h Holter monitoring. Two electrophysiological strategies were used, SN ablation and SN modification, with the latter being used more. Procedural acute success (using variably defined pre-determined endpoints) was 88.9%. Consistently, all groups reported high-output pacing from the ablation catheter to confirm absence of phrenic nerve stimulation before radiofrequency delivery. Need of pericardial access varied between 0% and 76.9%. Thirteen patients (8.5%) experienced severe procedural complications, and 15 patients (9.8%) required implantation of a pacemaker. At a mean follow-up interval of 28.1 ± 12.6 months, 86.4% of patients demonstrated successful outcomes. The symptomatic recurrence rate was 19.6%, and 29.8% of patients continued to receive antiarrhythmic drug therapy after procedural intervention. CONCLUSIONS: Inappropriate sinus tachycardia ablation/modification achieves acute success in the vast majority of patients. Complications are fairly common and diverse. However, symptomatic relief decreases substantially over longer follow-up periods, with a corresponding high recurrence rate.

Differential effect of ganglionic plexi ablation in a patient with neurally mediated syncope and intermittent atrioventricular block.

AIMS: In patients with severe neurally mediated syncope (NMS), radiofrequency catheter ablation (RFA) of ganglionic plexi (GP) has been proposed as a new therapeutic approach. Cardio-inhibitory response during NMS is usually related to the sinoatrial (SA) and less frequently to atrioventricular (AV) node. Differential effect of GP ablation on SA and AV node is poorly understood. METHODS AND RESULTS: We report a case of a 35-year-old female with frequent symptomatic episodes of advanced AV block treated by anatomically guided RFA at empirical sites of GPs. After RFA at the septal portion of the right atrium-superior vena cava junction, heart rate accelerated from 62 to 91 beats/min and PR interval prolonged from 213 to 344 ms. Sustained first-degree AV block allowed to observe directly the effects of subsequent RFA on the AV nodal properties. Subsequent RFA at right- and left-sided aspects of the inter-atrial septum had no further effect on heart rate and PR interval. Ablation at the inferior left GP was critical for restoration of normal AV conduction (final PR interval of 187 ms). No bradycardia episodes were observed by implantable loop recorder during the follow-up of 10 months and the patient was symptomatically improved. CONCLUSION: This is the first clinical case showing the differential effect of GP ablation on SA and AV nodal function, and critical importance of targeting the GP at the postero-inferior left atrium. The successful procedure corroborates clinical utility of ablation treatment instead of pacemaker implantation in selected patients with cardio-inhibitory NMS.

Rescuing cardiac automaticity in L-type Cav1.3 channelopathies and beyond.

Pacemaker activity of the sino-atrial node generates the heart rate. Disease of the sinus node and impairment of atrioventricular conduction induce an excessively low ventricular rate (bradycardia), which cannot meet the needs of the organism. Bradycardia accounts for about half of the total workload of clinical cardiologists. The 'sick sinus' syndrome (SSS) is characterized by sinus bradycardia and periods of intermittent atrial fibrillation. Several genetic or acquired risk factors or pathologies can lead to SSS. Implantation of an electronic pacemaker constitutes the only available therapy for SSS. The incidence of SSS is forecast to double over the next 50 years, with ageing of the general population thus urging the development of complementary or alternative therapeutic strategies. In recent years an increasing number of mutations affecting ion channels involved in sino-atrial automaticity have been reported to underlie inheritable SSS. L-type Cav 1.3 channels play a major role in the generation and regulation of sino-atrial pacemaker activity and atrioventricular conduction. Mutation in the CACNA1D gene encoding Cav 1.3 channels induces loss-of-function in channel activity and underlies the sino-atrial node dysfunction and deafness syndrome (SANDD). Mice lacking Cav 1.3 channels (Cav 1.3-/- ) fairly recapitulate SSS and constitute a precious model to test new therapeutic approaches to handle this disease. Work in our laboratory shows that targeting G protein-gated K+ (IKACh ) channels effectively rescues SSS of Cav 1.3-/- mice. This new concept of 'compensatory' ion channel targeting shines new light on the principles underlying the pacemaker mechanism and may open the way to new therapies for SSS.

Atrial standstill in sinus node disease due to extensive atrial fibrosis: impact on dual chamber pacemaker implantation.

AIMS: Atrial standstill is characterized by the absence of atrial activity. We report about a series of cases, in which conventional atrial pacemaker lead implantation in patients with symptomatic sinus node disease failed due to lack of excitable right atrial tissue, thus, prompting the diagnosis of atrial standstill. We hypothesized that mapping of the atria with subsequent identification of myocardium still amenable to atrial pacing would allow dual chamber pacemaker implantation. METHODS AND RESULTS: In four patients, atrial lead implantation failed. In these patients, spontaneous or fibrillatory electrical activity was absent but the atria could not be captured despite high stimulation voltages at conventional atrial sites. We suspected partial or complete atrial standstill and subsequently confirmed this hypothesis by conventional (n = 1) or electroanatomical mapping (n = 3). Areas of fibrotic tissue were present in all patients as identified by lack of spontaneous electrical activity and inability of local electrical capture via the mapping catheter. Surviving atrial tissue, which could be electrically captured with subsequent conduction of activity to the atrioventricular (AV) node, was present in three patients. Successful targeted atrial lead implantation at these sites was achieved in all these patients. Isolated sinus node activity without conduction to the atria was found in one patient. CONCLUSION: Partial atrial standstill may be present and prevent atrial lead implantation in patients with sinus node disease. In these patients, recognition of partial atrial standstill and identification of surviving muscular islets with connection to the AV node by mapping studies may still allow synchronous AV sequential pacing.

Sodium Hydroxide Pinpoint Pressing Permeation Method for the Animal Modeling of Sick Sinus Syndrome.

Sodium hydroxide pinpoint pressing permeation (SHPPP) was investigated in order to build a rat model of sick sinus syndrome (SSS), which is easy to operate and control the degree of damage, with fewer complications and applicable for large and small animals.Thirty healthy Wistar rats (15 males and 15 females, weighing 250-350 g) were randomly divided into 3 groups, namely a formaldehyde thoracotomy wet compressing group (FTWC), formaldehyde pinpoint pressing permeation group (FPPP) group, and SHPPP group. The number of surviving rats, heart rate (HR), sinoatrial node recovery time (SNRT), corrected SNRT (CSNRT), and sinoatrial conduction time (SACT) were recorded 3 days, one week, and two weeks after modeling.The achievement ratio of modeling was 10% in the FTWC group, 40% in the FPPP group, and 70% in the SHPPP group, and the differences were statistically significant (χ(2) = 7.250, P = 0.007). Meanwhile, the HR was reduced by about 37% in these 3 groups 3 days after modeling, while the reduction was maintained only in SHPPP (P > 0.05) and the HR was re-elevated in the FTWC and FPPP groups 2 weeks after modeling (P < 0.05). Additionally, the SNRT, cS-NRT, and SACT were significantly prolonged compared with pre-modeling in all 3 groups (P < 0.01).SHPPP was the best method with which to build an SSS model with stable and lasting low HR and high success rate of modeling, which might be helpful for further studies on the SSS mechanisms and drugs.

Selective and non-selective non-steroidal anti-inflammatory drugs differentially regulate pulmonary vein and atrial arrhythmogenesis.

BACKGROUND: Non-steroidal anti-inflammatory drugs (NSAIDs) increase the risk of atrial fibrillation (AF). This study investigated whether selective and non-selective NSAIDs differentially regulate the arrhythmogenesis of pulmonary veins and atria. METHODS: Conventional microelectrodes were used to record action potentials (APs) in isolated rabbit PVs, sinoatrial node (SAN), left atrium (LA), and right atrium (RA) preparations before and after celecoxib or indomethacin administration. A whole-cell patch clamp was used to record the sodium-calcium exchanger (NCX) current, L-type calcium current (ICa-L), and late sodium current (INa-late) before and after celecoxib administration in isolated PV cardiomyocytes. RESULTS: Celecoxib (0.3, 1, and 3 µM) reduced PV spontaneous beating rates, and induced delayed afterdepolarizations and burst firings in four of eight PV preparations (50%, p<0.05). Celecoxib also reduced SAN beating rates and decreased AP durations (APDs) in RA and LA, but did not change the resting membrane potential. Indomethacin (0.3, 1, 3, and 10 µM) changed neither the PV or SAN beating rates nor RA APDs, but it reduced LA APDs. Celecoxib (3 µM) significantly increased the NCX current and decreased the ICa-L, but did not change the INa-late. Ranolazine (10 µM) suppressed celecoxib (3 µM)-induced PV burst firings in 6 (86%, p<0.05) of 7 PVs. KB-R7943 (10 µM) suppressed celecoxib (3 µM)-induced PV burst firings in 5 (71%, p<0.05) of 7 PVs. CONCLUSIONS: Selective and non-selective NSAIDs differentially modulate PV and atrial electrophysiological characteristics. Celecoxib increased PV triggered activity through enhancement of the NCX current, which contributed to its arrhythmogenesis.

Disparate response of high-frequency ganglionic plexus stimulation on sinus node function and atrial propagation in patients with atrial fibrillation.

BACKGROUND: In patients with atrial fibrillation (AF), the autonomic nervous system is supposed to play an role in triggering AF; however, little is known of the effect on atrial conduction characteristics. OBJECTIVE: The purpose of this study was to study the effect of ganglionic plexus (GP) stimulation during sinus rhythm on atrial and pulmonary vein conduction in patients during thoracoscopic surgery for AF METHODS: In 25 patients, the anterior right ganglionic plexus (ARGP) was stimulated (16 Hz, at 1, 2, and 5 mA). Epicardial electrograms were recorded using a 48-electrode map from the right pulmonary vein (RPV) or right atrial (RA). Intra-atrial activation time (IAT), local activation time (LAT), and inhomogeneity of conduction (IIC) were determined. ECG parameters (P-P, P-R interval) were measured. RESULTS: P-P interval was 956 ± 157 ms (range 768-1368 ms), and P-R interval was 203 ± 37 ms (range 136-280 ms). After ARGP stimulation, a short-lasting increase of P-P interval was observed, more prominent at higher output (1 mA = 82 ms, 2 mA = 180 ms, 5 mA = 268 ms, all P <.01 vs baseline). P-R interval remained unchanged. IAT was 34.4 ms (range 5.6-50.3 ms) at the RA and 105.8 ms (range 79.7-163.3 ms) at the RPV. After 1-mA stimulation IAT increased, in patients taking beta-blockers (P = .001), or it decreased, and this change persisted after subsequent stimulation at higher current (1 mA, P = .001; 2 mA, P = .401; 5 mA, P = .593). Similar changes were observed for LAT and IIC. CONCLUSION: ARGP stimulation results in a short-lasting, output-dependent decrease in sinus node frequency due to a parasympathetic response. Stimulation of the ARGP induced a prolonged increase or decrease in conduction characteristics in patients with AF, consistent with a persistent differential parasympathetic and/or sympathetic response.

Permanent sinus dysfunction after pulmonary vein isolation ablation: observations and potential mechanisms.

Although transient sinus arrest has been reported during pulmonary vein isolation (PVI), the long-term impairment of sinus node after PVI has not been described. In this report, we present a case of sinus node dysfunction necessitating a permanent pacemaker, caused during PVI. Clinical data, intracardiac electrograms, and cardiac imaging were incompatible with previous sinus node dysfunction, sinus node artery occlusion, or an ectopic atrial rhythm from the pulmonary veins. Impairment of the neural pathways connecting the ganglionated plexi of the right superior pulmonary veins with the sinus node is a possible underlying mechanism.

Dominant frequency increase rate predicts transition from paroxysmal to long-term persistent atrial fibrillation.

BACKGROUND: Little is known about the mechanisms underlying the transition from paroxysmal to persistent atrial fibrillation (AF). In an ovine model of long-standing persistent AF we tested the hypothesis that the rate of electric and structural remodeling, assessed by dominant frequency (DF) changes, determines the time at which AF becomes persistent. METHODS AND RESULTS: Self-sustained AF was induced by atrial tachypacing. Seven sheep were euthanized 11.5±2.3 days after the transition to persistent AF and without reversal to sinus rhythm; 7 sheep were euthanized after 341.3±16.7 days of long-standing persistent AF. Seven sham-operated animals were in sinus rhythm for 1 year. DF was monitored continuously in each group. Real-time polymerase chain reaction, Western blotting, patch clamping, and histological analyses were used to determine the changes in functional ion channel expression and structural remodeling. Atrial dilatation, mitral valve regurgitation, myocyte hypertrophy, and atrial fibrosis occurred progressively and became statistically significant after the transition to persistent AF, with no evidence for left ventricular dysfunction. DF increased progressively during the paroxysmal-to-persistent AF transition and stabilized when AF became persistent. Importantly, the rate of DF increase correlated strongly with the time to persistent AF. Significant action potential duration abbreviation, secondary to functional ion channel protein expression changes (CaV1.2, NaV1.5, and KV4.2 decrease; Kir2.3 increase), was already present at the transition and persisted for 1 year of follow up. CONCLUSIONS: In the sheep model of long-standing persistent AF, the rate of DF increase predicts the time at which AF stabilizes and becomes persistent, reflecting changes in action potential duration and densities of sodium, L-type calcium, and inward rectifier currents.

[Atrial mechanical and electrical dysfunction in patient with Emery-Dreifuss muscular dystrophy reason of change in electrotherapeutical approach: frequent result of rare disease]. / Elektryczna i mechaniczna dysfunkcja przedsionków u pacjenta z dystrofia miesniowa Emery-Dreifussa przyczyna zmiany wyboru optymalnej formy elektroterapii: czeste powiklanie rzadkiej choroby.

We present a case of a 35 year-old male patient with Emery-Dreifuss muscular dystrophy diagnosed in the age of 12 who was assigned to dual chamber pacing system due to bradycardia primarily recognised as sinus node insufficiency with the atrio-ventricular nodal rhythm. During the procedure permanent electrical atrial stand-still without atrial capture were detected and the mode of stimulation was change to VVIR.

Inappropriate sinus tachycardia.

Inappropriate sinus tachycardia (IST) is a syndrome in which the sinus heart rate is inexplicably faster than expected and associated symptoms are present. The heart rate at rest, even in a supine position, can exceed 100 beats/min; minimal activity accelerates the rate rapidly and substantially. Patients with IST may require restriction from physical activity. Mechanisms responsible for IST are understood incompletely. It is important to distinguish IST from so-called appropriate sinus tachycardia and from postural orthostatic tachycardia syndrome, with which overlap may occur. Because the long-term outcome seems to be benign, treatment may be unnecessary or may be as simple as physical training. However, for patients with intolerable symptoms, therapeutic measures are warranted. Even at high doses, ß-adrenergic blockers, the first-line therapy, often are ineffective; the same is true for most other medical therapies. In rare instances, catheter- or surgically- based right atrial or sinus node modification may be helpful, but even this is fraught with limited efficacy and potential complications. Overtreatment, in an attempt to reduce symptoms, can be difficult to avoid, but is discouraged.