Stem cell-derived nodal-like cardiomyocytes as a novel pharmacologic tool: insights from sinoatrial node development and function.

Since the first reports on the isolation and differentiation of stem cells, and in particular since the early success in driving these cells down a cardiac lineage, there has been interest in the potential of such preparations in cardiac regenerative therapy. Much of the focus of such research has been on improving mechanical function after myocardial infarction; however, electrophysiologic studies of these preparations have revealed a heterogeneous mix of action potential characteristics, including some described as "pacemaker" or "nodal-like," which in turn led to interest in the therapeutic potential of these preparations in the treatment of rhythm disorders; several proof-of-concept studies have used these cells to create a biologic alternative to electronic pacemakers. Further, there are additional potential applications of a preparation of pacemaker cells derived from stem cells, for example, in high-throughput screens of new chronotropic agents. All such applications require reasonably efficient methods for selecting or enriching the "nodal-like" cells, however, which in turn depends on first defining what constitutes a nodal-like cell since not all pacemaking cells are necessarily of nodal lineage. This review discusses the current state of the field in terms of characterizing sinoatrial-like cardiomyocytes derived from embryonic and induced pluripotent stem cells, markers that might be appropriate based on the current knowledge of the gene program leading to sinoatrial node development, what functional characteristics might be expected and desired based on studies of the sinoatrial node, and recent efforts at enrichment and selection of nodal-like cells.

Early plasma exchange for treating ricin toxicity in children after castor bean ingestion.

Plasma exchange (PE) for the treatment of ricin toxicity has not been previously reported. Here we describe the use of PE to treat children who experienced ricin toxicity after ingesting castor beans. Seven children (median age: 8.1 years) who consumed castor beans (median: 5 beans) were treated with PE. All had bradycardia and sinus arrhythmia, and most had experienced episodes of vomiting and/or diarrhea. PE settings were blood flow, 50-80 mL/min; PE rate, 600-800 mL/h; volume of exchange, 1440-1950 mL. Median time from ingestion to PE was 73 h. All clinical symptoms disappeared and vital signs rapidly returned to normal after PE; no severe organ dysfunction occurred. All children were discharged and recovered uneventfully. Concentrations of all serum biochemical parameters significantly decreased immediately after PE. Some, but not all, of these parameters were also significantly decreased at 48 and 72 h after PE compared with before PE. Our findings suggest that PE can be an effective early intervention in the treatment of ricin toxicity due to castor bean ingestion.

Impact of right-ventricular apical pacing on the optimal left-ventricular lead positions measured by phase analysis of SPECT myocardial perfusion imaging.

PURPOSE: The use of SPECT phase analysis to optimize left-ventricular (LV) lead positions for cardiac resynchronization therapy (CRT) was performed at baseline, but CRT works as simultaneous right ventricular (RV) and LV pacing. The aim of this study was to assess the impact of RV apical (RVA) pacing on optimal LV lead positions measured by SPECT phase analysis. METHODS: This study prospectively enrolled 46 patients. Two SPECT myocardial perfusion scans were acquired under sinus rhythm with complete left bundle branch block and RVA pacing, respectively, following a single injection of (99m)Tc-sestamibi. LV dyssynchrony parameters and optimal LV lead positions were measured by the phase analysis technique and then compared between the two scans. RESULTS: The LV dyssynchrony parameters were significantly larger with RVA pacing than with sinus rhythm (p ~0.01). In 39 of the 46 patients, the optimal LV lead positions were the same between RVA pacing and sinus rhythm (kappa = 0.861). In 6 of the remaining 7 patients, the optimal LV lead positions were along the same radial direction, but RVA pacing shifted the optimal LV lead positions toward the base. CONCLUSION: The optimal LV lead positions measured by SPECT phase analysis were consistent, no matter whether the SPECT images were acquired under sinus rhythm or RVA pacing. In some patients, RVA pacing shifted the optimal LV lead positions toward the base. This study supports the use of baseline SPECT myocardial perfusion imaging to optimize LV lead positions to increase CRT efficacy.

The ventriculophasic response: relationship to sinus arrhythmia and the duration of interposed QRS complexes.

BACKGROUND: The ventriculophasic response (VR) refers to shortening of sinus cycle length during heart block when a QRS complex is interposed between 2 P waves. Our purpose was to analyze its relationship to respiratory sinus arrhythmia (SA) and to compare VR in relation to paced versus intrinsic QRS complexes. METHODS: Patients with advanced heart block had their pacer devices temporarily programmed to ventricular inhibited mode at 30 ppm. In 35 subjects, we analyzed VR and SA before, during and after 3 cycles of deep breathing. In 16 other patients we compared VR in the presence of paced versus narrower intrinsic QRS complexes. RESULTS: The magnitude of P-P interval shortening surrounding QRS complexes during inspiration correlated with SA (r = 0.36, P = 0.03). The prevalence of VR increased from 37% at baseline to 77% of subjects during deep breathing (P = 0.02). The mean P-P interval shortening was greater surrounding intrinsic QRS complexes than paced QRS complexes (3.6 ± 3.6% vs. 1.4 ± 1.1%, P = 0.02). The prevalence of VR increased from 25% during paced rhythm to 56% when intrinsic complexes were present. CONCLUSION: VR, like SA, increases with deep breathing and likely reflects intact parasympathetic nervous system function. Its increase in the presence of narrower beats suggests it may reflect ventricular synchrony.

A decrease in serum aldosterone level is associated with maintenance of sinus rhythm after successful cardioversion of atrial fibrillation.

BACKGROUND: The activation of the renin-angiotensin-aldosterone system has been implicated in the progression of atrial structural remodeling during atrial fibrillation (AF). However, consequences of the changes of aldosterone in AF have not been evaluated. OBJECTIVES: This study's aim was to evaluate changes of serum aldosterone concentration after successful cardioversion of persistent AF and to determine the prognostic value of these changes. METHODS: The prospective, single center study included 45 consecutive patients with nonvalvular persistent AF and preserved left ventricular systolic function, referred for cardioversion. None of the patients were taking aldosterone antagonists. Blood samples for aldosterone measurement were collected twice: 24 hours before and 24 hours after cardioversion. RESULTS: Forty-three patients were successfully converted to sinus rhythm. On the 30th day following cardioversion, 24 patients maintained sinus rhythm (group A), 19 patients relapsed to AF (group B). Serum aldosterone concentration before cardioversion did not differ significantly between both groups (175.6 +/- 112.82 pg/mL vs 125.8 +/- 51.2 pg/mL; P = 0.25). However, in group A serum aldosterone level decreased significantly within 24 hours after cardioversion, from 175.6 +/- 112.8 pg/mL to 101.4 +/- 44.2 pg/mL (P = 0.0034). In group B, the aldosterone level before and after cardioversion did not differ significantly (125.8 +/- 51.2 pg/mL vs 118.2 +/- 59.6 pg/mL; P = 0.68). Logistic regression analysis revealed that a decrease in plasma aldosterone concentration after direct current cardioversion more than 13.2 pg/mL predicted sinus rhythm maintenance in a 30-day follow-up, with 87% sensitivity and 64% specificity. CONCLUSIONS: There is a positive correlation between the fall in aldosterone concentration 24 hours after cardioversion and maintenance of sinus rhythm during 30 days of observation.

[Determination of the cause of repetitive syncopal States with the help of registration of electrocardiogram at the background of provocative test].

A clinical case of repetitive syncopal states in an adolescent with episodes of significant asystoles lasting up to 32 s is presented. These episodes were detected only with the help of electrocardiogram registered during provocative test. Beyond provoking factors the child had signs of insignificant sinus node dysfunction which did not allow to designate the state of the patient as severe and prescribe adequate treatment. We consider this case as demonstration of necessity of provocative tests in conjunction with ECG monitoring in children with episodes of fainting (syncopal states).

A randomized comparison of amiodarone and class IC antiarrhythmic drugs to treat atrial fibrillation in patients paced for sinus node disease: the Prevention Investigation and Treatment: A Group for Observation and Research on Atrial arrhythmias (PITAGORA) trial.

BACKGROUND: Rhythm control is an important goal in the treatment of recurrent atrial tachyarrhythmias (AT). The PITAGORA study was a randomized trial in patients paced for sinus node disease (SND), designed to test the noninferiority of class IC antiarrhythmic drugs (AADs) to amiodarone in terms of a primary end point composed of death, permanent AT, cardiovascular hospitalization, atrial cardioversion, or AAD change. METHODS: Randomization was stratified to assign 2 patients to amiodarone and 2 patients to class IC AADs: propafenone or flecainide. One hundred seventy-six patients (46% men, 72 +/- 8 years) were enrolled. Device diagnostics continuously monitored AT recurrences and duration. RESULTS: In a mean follow-up of 20 +/- 9 months, the primary end point occurred in 23 (30.7%) of 75 class IC patients and in 28 (40.0%) of 70 amiodarone patients. The absolute difference in the end point incidence (-9.3%; 95% CI between 3.7% and -22.3%) confirmed the noninferiority of class IC to amiodarone (P = .007). Kaplan-Meier 1-year freedom from AT episodes >10 minutes, 1 day, and 7 days was 40%, 73%, and 91% for amiodarone and 28%, 78%, and 86% for class IC AADs (P = nonsignificant). CONCLUSIONS: In patients paced for SND and suffering from AT, class IC AADs proved not to be inferior to amiodarone in terms of the primary composite end point described or end points which were differently composed of mortality, efficacy, or AAD side effects. The AADs studied also showed similar results in terms of symptoms, quality of life, and freedom from AT recurrences.

Atrial lead location at the Bachmann's bundle region results in a low incidence of far field R-wave sensing.

AIMS: The aim of the study was to investigate far field R-wave sensing (FFRS) rate and characteristics at different right atrial (RA) positions in patients treated with multisite atrial pacing, with the RA lead implanted at the Bachmann's bundle (BB) area in 69 patients, in comparison to RA appendage (RAA) in 70 patients. METHODS AND RESULTS: All measurements were done during sinus rhythm in supine patients, with unipolar (UP) and bipolar (BP) sensing configuration. The presence, amplitude threshold (FFRS trsh) and FFRS timing were determined. Sensing safety margin was defined as the ratio of sensed P-wave vs. FFRS trsh, for both the minimal (Pmin) and the mean (Pmean) P-wave amplitude. At both atrial locations BP sensing was superior to UP in FFRS rejection (P < 0.0001). At 0.5 mV sensitivity level (BP) FFRS occurred in 1% of patients at the BB site vs. 11% at the RAA (P = 0.01). FFRS trsh (BP) was 0.2 +/- 0.1 mV at the BB vs. 0.4 +/- 0.3 mV in the RAA position (P < 0.0001). Sensing safety margin, when determined for the Pmin amplitude was > or =5 in 99% of patients from the BB group, in comparison to 66% of RAA patients (P < 0.0001), in whom it was <2 in 13%. Even with the use of BP leads equipped with a 10 mm tip-to-ring spacing FFRS incidence was lower at the BB site (P < 0.01), FFRS trsh was lower (P < 0.001), and sensing safety margin was higher vs. RAA (P = 0.002). CONCLUSION: Bachmann's bundle area features optimal conditions for signal sensing, and such atrial lead positioning may offer advantages to prevent oversensing of R-wave, thus improving functioning of standard dual chamber pacemakers, ICDs and CRT-Ds.

Benefit of cardiac resynchronization therapy in atrial fibrillation patients vs. patients in sinus rhythm: the role of atrioventricular junction ablation.

AIMS: To assess the clinical benefit of cardiac resynchronization therapy (CRT) in patients with atrial fibrillation (AF) compared with patients in sinus rhythm (SR), and to evaluate the impact of atrioventricular junction (AVJ) ablation on the outcome of AF patients undergoing CRT. METHODS AND RESULTS: We conducted a retrospective analysis of 131 consecutive heart failure (HF) patients who underwent CRT implantation. Three groups were considered: SR (n = 78), AF with AVJ ablation (n = 26), and AF without AVJ ablation (n = 27). Patients were evaluated for the occurrence of cardiac death, hospitalization for HF, and responsiveness to CRT (survival with improvement of >or=1 New York Heart Association class at 6 months). The three groups showed a significant improvement in functional class. However, the proportion of responders was significantly lower in AF patients without AVJ ablation (52 vs. 79% in SR and 85% in AF with AVJ ablation, P < 0.008). Atrial fibrillation without AVJ ablation was also independently associated with mortality (HR 5.22, 95% CI: 1.60-17.01, P = 0.006) and hospitalization for HF during the first 12 months (HR 6.23, 95% CI: 2.09-18.54, P = 0.001). The outcomes of AF with AVJ ablation patients were similar to the outcomes of patients in SR. CONCLUSION: Sinus rhythm and AF patients display similar survival and clinical improvement after CRT implantation, provided that AVJ ablation is performed in the latter.

Atrial vs. dual-chamber cardiac pacing in sinus node disease: a register-based cohort study.

AIMS: In patients with sinus node disease, dual-chamber pacing (DDD) possibly results in adverse effects on the ventricular function. We have compared the incidence of cardiovascular morbidity and mortality in patients with sinus node disease and with atrioventricular (AV) synchronous pacemakers, DDD vs. atrial pacing (AAI). METHODS AND RESULTS: A nation-wide population-based cohort of 8777 patients with AAI- or DDD-mode pacemakers was followed during 12 years. The cohort was linked to national healthcare and census registers. Patients with DDD pacing and without any pre-implant admission for atrial fibrillation or flutter had an increased risk of post-implant fibrillation or flutter, in relation to corresponding AAA patients [hazard ratio (HR) = 1.30; 95% confidence interval (CI) 1.10-1.52]. A slight increase in the risk of any cardiovascular disease (HR = 1.07; CI, 1.00-1.15), and all-cause mortality (HR = 1.12; CI, 1.00-1.25), was seen among DDD patients, in relation to AAI patients, but there was no significant difference in the risk of ischaemic or unspecified stroke (HR = 1.14; CI, 0.94-1.37). Among DDD patients, the all-cause mortality did not differ from the general population [standardized mortality ratio (SMR) = 1.04; CI, 0.98-1.11]. Patients with AAI, however, had a decreased all-cause mortality risk (SMR = 0.89; CI, 0.82-0.97). CONCLUSION: Our results support AAI as the preferred mode of pacing in patients with sinus node disease, and a normal AV node function.

Ventricular pacing or dual-chamber pacing for sinus-node dysfunction.

BACKGROUND: Dual-chamber (atrioventricular) and single-chamber (ventricular) pacing are alternative treatment approaches for sinus-node dysfunction that causes clinically significant bradycardia. However, it is unknown which type of pacing results in the better outcome. METHODS: We randomly assigned a total of 2010 patients with sinus-node dysfunction to dual-chamber pacing (1014 patients) or ventricular pacing (996 patients) and followed them for a median of 33.1 months. The primary end point was death from any cause or nonfatal stroke. Secondary end points included the composite of death, stroke, or hospitalization for heart failure; atrial fibrillation; heart-failure score; the pacemaker syndrome; and the quality of life. RESULTS: The incidence of the primary end point did not differ significantly between the dual-chamber group (21.5 percent) and the ventricular-paced group (23.0 percent, P=0.48). In patients assigned to dual-chamber pacing, the risk of atrial fibrillation was lower (hazard ratio, 0.79; 95 percent confidence interval, 0.66 to 0.94; P=0.008), and heart-failure scores were better (P<0.001). The differences in the rates of hospitalization for heart failure and of death, stroke, or hospitalization for heart failure were not significant in unadjusted analyses but became marginally significant in adjusted analyses. Dual-chamber pacing resulted in a small but measurable increase in the quality of life, as compared with ventricular pacing. CONCLUSIONS: In sinus-node dysfunction, dual-chamber pacing does not improve stroke-free survival, as compared with ventricular pacing. However, dual-chamber pacing reduces the risk of atrial fibrillation, reduces signs and symptoms of heart failure, and slightly improves the quality of life. Overall, dual-chamber pacing offers significant improvement as compared with ventricular pacing.

Cardiac vagal control in the severity and course of depression: the importance of symptomatic heterogeneity.

BACKGROUND: Impaired cardiac vagal control (CVC), as indexed by respiratory sinus arrhythmia, has been investigated as a risk factor for major depressive disorder (MDD), but prior findings are mixed with respect to whether impaired CVC predicts greater global depression severity and/or a more severe course of disorder. One possible explanation for mixed findings is that CVC abnormalities in MDD are related more closely to specific depression symptoms than to the syndrome as a whole. METHODS: Depression severity (both global and symptom-specific indices) and electrocardiogram measures of resting CVC were obtained from 151 diagnosed MDD participants at intake, before randomization to a novel treatment for depression (acupuncture), and again after 8 and 16 weeks. RESULTS: Resting CVC did not predict global indices of depression in cross-sectional or longitudinal analyses. In symptom-specific analyses, resting CVC was positively related to sad mood and crying and inversely related to middle and late insomnia. Improvement in late insomnia was related to increases in CVC over time. LIMITATIONS: Relationships between CVC and MDD were studied only within the clinical range of severity. Symptom analyses were exploratory and hence did not correct for Type I error. CONCLUSIONS: Resting CVC did not exhibit concurrent or prospective relations with overall depression severity but a few specific symptoms did. Symptomatic heterogeneity across samples may account for mixed findings within the CVC-depression literature.

Management of complications during moderate and deep sedation: respiratory and cardiovascular considerations.

The risk for complications while providing moderate and deep sedation is greatest when caring for patients already medically compromised. It is reassuring that significant untoward events can generally be prevented by careful preoperative assessment, along with attentive intraoperative monitoring and support. Nevertheless, we must be prepared to manage untoward events should they arise. This continuing education article will review critical aspects of patient management of respiratory and cardiovascular complications.

Management of far-field R wave sensing for the avoidance of inappropriate mode switch in dual chamber pacemakers: results of the FFS-test study.

BACKGROUND AND OBJECTIVE: Far-field R wave sensing (FFS) in the atrial channel of dual chamber pacemakers is a relevant source for inappropriate mode switch from the DDD mode to the DDI or VDI mode. Inappropriate loss of atrioventricular synchrony due to false positive mode switch is hemodynamically disadvantageous, may induce atrial tachyarrhythmias, can lead to pacemaker syndrome, and impairs the reliability of pacemaker Holter data. The aim of the study was to determine whether individual adjustment of the postventricular atrial blanking period (PVAB) based on an additional test is effective in avoiding inappropriate mode switch due to FFS when compared with standard programming of the PVAB. METHODS: A total of 207 patients were supplied with a St. Jude Medical Identity DR or Identity ADx DR dual chamber pacemaker for sinus nodal disease (n = 84), atrioventricular block (n = 79), binodal disease (n = 35), or other indications (n = 9). At hospital discharge, they were randomized to an individually optimized PVAB (n = 100) or to a control group with the PVAB left at the nominal of 100 msec (n = 107). Primary endpoint was the occurrence of inappropriate mode switch due to FFS within 3 months after pacemaker implantation assessed by stored electrograms of the pacemaker. RESULTS: At the 3-month follow-up, 28/107 (26%) patients with the standard programming of the PVAB showed at least one episode of inappropriate mode switch due to FFS versus 10/100 (10%) patients with optimized PVAB (P < 0.01). The optimized PVAB was shorter than the nominal PVAB in about one-third of patients and longer in about two-third of patients. Different atrial lead localizations were not associated with the occurrence of inappropriate mode switch. CONCLUSIONS: Individual adjustment of the PVAB significantly reduces the incidence of inappropriate mode switch due to FFS.

Atrial high rate episodes detected by pacemaker diagnostics predict death and stroke: report of the Atrial Diagnostics Ancillary Study of the MOde Selection Trial (MOST).

BACKGROUND: Some current pacing systems can automatically detect and record atrial tachyarrhythmias that may be asymptomatic. We prospectively studied a 312-patient (pt) subgroup of MOST (MOde Selection Trial), a 2010-patient, 6-year randomized trial of DDDR versus VVIR pacing in sinus node dysfunction (SND). The purpose of the study was to correlate atrial high rate events (AHREs) detected by pacemaker diagnostics with clinical outcomes. METHODS AND RESULTS: Pacemakers were programmed to log an AHRE when the atrial rate was >220 bpm for 10 consecutive beats. Analysis was confined to patients with at least 1 AHRE duration exceeding 5 minutes. The 312 patients were median age 74 years, 55% female, and 60% had a history of SVT. 160 of 312 (51.3%) patients enrolled had at least 1 AHRE >5 minutes duration over median follow-up of 27 months. Cox proportional hazards analysis assessed the relationship of AHREs with clinical events, adjusting for prognostic variables and baseline covariates. The presence of any AHRE was an independent predictor of the following: total mortality (hazard ratio AHRE versus no AHRE and 95% confidence intervals=2.48 [1.25, 4.91], P=0.0092); death or nonfatal stroke (2.79 [1.51, 5.15], P=0.0011); and atrial fibrillation (5.93 [2.88, 12.2], P=0.0001). There was no significant effect of pacing mode on the presence or absence of AHREs. CONCLUSIONS: AHRE detected by pacemakers in patients with SND identify patients that are more than twice as likely to die or have a stroke, and 6 times as likely to develop atrial fibrillation as similar patients without AHRE.

Relation between mode of pacing and long-term survival in the very elderly.

OBJECTIVES: This study analyzes the relationship between pacing mode and long-term survival in a large group of very elderly patients (> or = 80 years old). BACKGROUND: The relationship between pacing mode and long-term survival is not clear. Because the number of very elderly who are candidates for pacing is increasing, issues related to pacemaker (PM) use in the elderly have important clinical and economic implications. METHODS: We retrospectively reviewed 432 patients (mean age, 84.5+/-3.9 years) who received their initial PM (ventricular in 310 and dual chamber in 122) between 1980 and 1992. Follow-up was complete (3.5+/-2.6 years). Observed survival was estimated by the Kaplan-Meier method. Age- and gender-matched cohorts from the Minnesota population were used for expected survival. Log-rank test and Cox regression hazard model were used for univariate and multivariate analyses. RESULTS: Patients with ventricular PMs appeared to have poor overall survival compared with those with dual-chamber PMs. Observed survival after PM implantation in high grade atrioventricular block (AVB) patients was significantly worse than expected survival of the age- and gender-matched population (p < 0.0001), whereas observed survival of patients with sinus node dysfunction was not significantly different from expected survival of the matched population (p = 0.413). By univariate analysis, ventricular pacing in patients with AVB appeared to be associated with poor survival compared with dual-chamber pacing (hazard ratio [HR] 2.08; 95% confidence interval [CI] 1.33 to 3.33). After multivariate analysis, this difference was no longer significant (HR 1.41; 95% CI 0.88 to 2.27). Independent predictors of all-cause mortality were number of comorbid illnesses, New York Heart Association functional class, left ventricular depression and older age at implant. Pacing mode was not an independent predictor of overall survival. Older age at implantation, diabetes mellitus, dementia, history of paroxysmal atrial fibrillation and earlier year of implantation were independent predictors of ventricular pacemaker selection. CONCLUSIONS: After PM implantation, long-term survival among very elderly patients was not affected by pacing mode after correction of baseline differences. Selection bias was present in pacing mode in the very elderly, with ventricular pacing selected for sicker and older patients, perhaps partly explaining the apparent "beneficial impact on survival" observed with dual-chamber pacing.

Rate versus rhythm control in patients with atrial fibrillation: what the trials really say.

Despite new insights into the pathophysiological triggers of atrial fibrillation (AF) and the development of novel ablative techniques and antiarrhythmic drugs, the management of this chronic rhythm disturbance remains problematic. At present, there are two fundamental interventional choices: restoration and maintenance of normal sinus rhythm (NSR) or control of the ventricular rate. While there are compelling theoretical benefits in restoring and maintaining NSR, until recently there has been little evidence supporting the comparative advantages of either strategy. During the past few years, five randomised trials investigating the two treatment strategies have been completed: PIAF (Pharmacological Intervention in Atrial Fibrillation), STAF (Strategies of Treatment of Atrial Fibrillation), RACE (RAte Control versus Electrical conversion), AFFIRM (Atrial Fibrillation Follow-up of Rhythm Management) and HOT-CAFE (How to Treat Chronic Atrial Fibrillation). Results from these studies indicate that a strategy of rate control in AF patients can be at least as effective as efforts to control rhythm with respect to several specific outcomes. These trials have also revealed the necessity of continuing antithrombotic treatment even when long-term sinus rhythm is obtained. However, these trials had different patient selection criteria, endpoints and therapeutic interventions, limiting the applicability of their findings to all AF populations. This article looks beyond the primary results from these important studies, using recent substudy analyses to draw new conclusions and to generate hypotheses that will require prospective evaluation in adequately powered trials. One substudy suggested, for instance, that failure of rhythm control to show superiority may be a result of the toxicity of current antiarrhythmic drugs. New class III compounds with novel mechanisms are now in varying stages of clinical development. These drugs appear to block multiple membrane ion channels, with predominant effects on the atria and low proarrhythmic potential. It is anticipated that these agents will be safer than, and at least as effective as, currently available drugs, thereby reducing AF-related morbidity and mortality. Until more effective treatments are available, physicians should use the evidence generated from the major studies to guide decision making based upon the characteristics and symptomatic presentation of individual patients.

Prognosis of patients permanently paced for sick sinus syndrome.

In 39 patients (mean age, 66 years) treated for sick sinus syndrome (SSS) with pacemaker insertion, the long-term prognosis was studied. Fifteen patients (42%) died during the follow-up period of 6 to 59 months (mean, 25 months). Three patients were unavailable for follow-up. Eleven of the 15 deaths (73%) were cardiac-related, yet none could be associated with either an arrhythmia or pacemaker failure. Symptoms recurred or persisted after pacemaker insertion in 14 patients (mean age, 71 years), nine of whom died (31 deaths per 100 patient follow-up years). Twenty-two patients (mean age, 63 years) were asymptomatic after pacer insertion, six of whom died (11 deaths per 100 patient follow-up years). These follow-up results demonstrate a poor long-term prognosis in patients with SSS and persistent symptoms following permanent pacing.

[Coexistence of occupational exposure to lead and sleep apnea syndrome as a cause of hypertension and arrhythmias. A case report]. / Wspólistnienie zawodowego narazenia na dzialanie olowiu oraz zespolu bezdechu sennego przyczyna nadcisnienia tetniczego i zaburzen rytmu serca. Opis przypadku.

A case of a 54-year-old man occupationally exposed to lead with diagnosed obstructive sleep apnea, hypertension and implanted artificial pacemaker due to atrioventricular dissociation of the third degree and pauses in sinus rhythm is presented.