Complications with the MICRA TPS Pacemaker System: Persistent Complete Heart Block and Late Capture Failure.

A Medtronic MICRA transcatheter pacing system (Medtronic, Minneapolis, MN, USA) was implanted in an 86-year-old patient with sick sinus syndrome and left bundle branch block after transfemoral aortic valve implantation. During implantation she developed a persistent complete heart block due to manipulation with the large-bore delivery catheter. Two weeks later, acute pacemaker dysfunction occurred due to massive increase of pacing threshold and impedance without obvious pacemaker dislocation or myocardial perforation. Recurrent capture failure was seen with pacing output set at 5 V/1.0 ms. Hence, microdislocation or fixation of the tines in the right ventricular trabeculae has to be assumed.

Health economic evaluation of single-lead atrial pacing vs. dual-chamber pacing in sick sinus syndrome.

AIMS: The recent Danish Multicentre Randomized Trial on Single-Lead Atrial (AAIR) Pacing versus Dual-Chamber (DDDR) Pacing in Sick Sinus Syndrome (DANPACE) suggested DDDR pacing as standard care. However, previous findings supported the routine use of AAIR pacing. This study investigated the cost-effectiveness of DDDR pacing compared with AAIR pacing for sick sinus syndrome. METHODS AND RESULTS: A decision-analytical model based on patient-level data from three randomized trials was designed from the Danish healthcare system's perspective. The main outcomes were lifetime costs, quality-adjusted lifeyears (QALYs), and net monetary benefit. Quality-adjusted lifeyears were calculated by utilizing community-based preferences. Costs were calculated by utilizing the extensive data on resource consumption, from the DANPACE trial. Data were pooled and adjusted for baseline differences. Dual-chamber pacing was shown to be cost-effective in all the analyses using a willingness-to-pay (WTP) threshold of £20,000/QALY, and most analyses using a WTP of £30,000/QALY. When pooling the data and adjusting for baseline differences, Monte Carlo simulations revealed a 51-71% probability of DDDR pacing being cost-effective at a WTP of £20,000/QALY, and a 42-58% probability at a WTP of £30,000/QALY. Dual-chamber pacing was most likely to be cost-effective among elderly patients with comorbidity. The expected value of perfect information was low and initiation of additional publicly funded Danish trials was discouraged. CONCLUSION: Dual-chamber pacing is likely to be a cost-effective treatment for sick sinus syndrome patients.

Apparent acute reversible right ventricular pacing-induced left ventricular dysfunction.

We report the case of a 70-year-old Caucasian male with a dual chamber (right atrium/right ventricle) pacemaker implanted for sinus node dysfunction and not pacemaker (PM) dependent who was found to have an apparent acute worsening of left ventricular (LV) function with right ventricular (RV) apical pacing caused by the mode switch to VVI pacing as battery depletion occurred. LV dysfunction resolved immediately with RV pacing turned off. To our knowledge, this is the first report of this phenomenon.

System upgrade and its complications in patients with a single lead atrial pacemaker: data from the DANPACE trial.

AIMS: To investigate the indications for system upgrade with single lead atrial pacing (AAIR), complications associated with these re-interventions, and possible predictors for system upgrade among patients included in the Danish Multicenter Randomized Trial on AAIR vs. dual-chamber pacing (DDDR) in sick sinus syndrome (DANPACE). METHODS AND RESULTS: A total of 707 of 1415 patients were randomized to AAIR pacing. Mean follow-up was 5.5 ± 2.6 years. Information on indications for system upgrade and complications were collected by reviewing patient charts. Multiple logistic regression was used to estimate adjusted odds ratios (aOR) with 95% confidence intervals (CI) for the association between predictors and system upgrade. Sixty-six patients (9.3%) in the AAIR group underwent system upgrade. Fifty-nine of these patients (89.3%) had a documented class I indication for system upgrade. Age (aOR 0.98 for each 1-year increase in age; 95% CI 0.6-1.0), and left atrial enlargement (aOR 1.9; 95% CI 1.0-3.8) were predictors for system upgrade. No single clinically applicable predictor for upgrade was identified. A total of 11 patients (16.7%) experienced at least one major complication after system upgrade. CONCLUSION: The majority of patients with AAIR pacing who underwent system upgrade had a class I indication. The incidence of major complications after system upgrade was high. The present data support the use of DDDR pacing rather than AAIR pacing in sick sinus syndrome.

Cardiac pacing in paediatric patients with congenital heart defects: transvenous or epicardial?

AIMS: Cardiac pacing is a difficult technique in children, particularly in patients with congenital heart defects (CHDs). Few studies to date have addressed this topic. METHODS AND RESULTS: We performed a retrospective analysis of the results of a single centre. Between 1982 and 2008, 287 patients with CHD, median age of 5 years (25-75%, 1-11) underwent cardiac pacing for sinus node dysfunction (SND) and atrioventricular block (AVB); 97% of patients underwent at least one heart surgery. Endocardial systems (Endo) were implanted in 117 patients, epicardial systems (Epi) in 170, with 595 leads (228 Endo, 367 Epi). Endocardial systems showed a significantly older age group with more frequent SND; Epi a younger age group, with more frequent AVB, greater number of surgical interventions. Perioperative complications were mortality 0.6% (Epi), pericardial effusion 0.6% (Epi), and haemothorax 3.4% (Endo). The median follow-up is 5 (2-10) years: the pacing system failed in 29% of patients, 13% Endo, and 40% Epi (P < 0.0001). Multivariate analysis showed a significantly higher risk of failure for Epi, a lower implant age, greater the number of leads implanted. The risk of malfunction of the leads increases significantly for Epi and the younger age when implanted. The steroid-eluting leads have a lower risk of malfunction (P = 0.05), steroid-eluting Endo leads provide significantly better outcomes than Epi. CONCLUSION: Cardiac pacing in paediatric patients with CHD shows satisfactory results in the long term. Endocardial systems show significantly better results than Epi systems. A younger age when implanted is a risk factor for complications at follow-up.

Long-term effect of septal or apical pacing on left and right ventricular function after permanent pacemaker implantation.

BACKGROUND: Right ventricular (RV) pacing is associated with left ventricular (LV) dysfunction. However, the effects of RV pacing at different sites on both LV and RV function have rarely been studied before. We want to determine whether different RV pacing sites differentially affect LV and RV deformation by using speckle tracking echocardiography (STE). METHODS: The subjects were 73 patients who had undergone dual-chamber permanent pacemaker implantation and did not have structural heart diseases. LV and RV global longitudinal strains (GLS) were measured using STE to determine subtle changes in LV function. Twenty-three patients without pacing after pacemaker implantation served as controls; 14 and 36 patients showed apical and septal pacing, respectively. RESULTS: There were no significant intergroup demographic differences. LV biplane ejection fractions in the septal- and apical-pacing groups were significantly lower than those in the controls. The GLS LV values were similar between the control and septal-pacing groups, but they were lower in the apical-pacing group. Multivariate analysis revealed that cumulative pacing loads and apical pacing were independent factors associated with lower GLS LV values. The GLS RV values were similar between the control and apical-pacing groups; however, they were lower in the septal-pacing group. CONCLUSION: We concluded that patients with septal pacing have significantly higher GLS LV and more modest decreases in GLS RV values than patients with apical pacing. Thus, septal pacing may be not necessarily preferable in patients without significant heart disease undergoing dual-chamber permanent pacemaker implantation.

A 2:1 AV rhythm: an adverse effect of a long AV delay during DDI pacing and its prevention by the ventricular intrinsic preference algorithm in DDD mode.

A 91-year-old woman received a dual-chamber pacemaker for sick sinus syndrome and intermittently abnormal atrioventricular (AV) conduction. The pacemaker was set in DDI mode with a 350-ms AV delay to preserve intrinsic ventricular activity. She complained of palpitation during AV sequential pacing. The electrocardiogram showed a 2:1 AV rhythm from 1:1 ventriculoatrial (VA) conduction during ventricular pacing in DDI mode with a long AV interval. After reprogramming of the pacemaker in DDD mode with a 250-ms AV interval and additional 100-ms prolongation of the AV interval by the ventricular intrinsic preference function, VA conduction disappeared and the patient's symptom were alleviated without increasing unnecessary right ventricular pacing.

The immediate effects of pacemaker-related electric remodelling on left ventricular function in patients with sick sinus syndrome.

AIMS: The immediate effects of electric remodelling on the left ventricular (LV) function by dual-chamber pacemakers remain unknown. The purpose of our study was to assess the interaction between heart rates and right ventricular pacing (VP) on LV contractility and diastolic function. METHOD AND RESULTS: Twenty-five patients with dual-chamber pacemakers and sick sinus syndrome were evaluated. Echocardiographic examinations included standard and tissue-Doppler echocardiography at bilateral mitral annulus margins under either the intrinsic atrio-ventricular sequential conduction (ventricular sensing; VS) mode or right ventricular apical pacing (VP) mode. Under either mode, we accelerated the pacing rate at an increment of 15 b.p.m. step-by-step from 60 to 90/min. The tissue-Doppler echocardiography of mitral annulus showed that under the VS status, accelerating atrial pacing rate from 60 to 90 b.p.m. enhanced A'-wave velocity (P < or =0.002), whereas no significant change of LV ejection fraction (LVEF) and E'-wave velocity were noted. Under the VP status, acceleration of pacing rates exerted no effect on the LVEF, E'-, and A'-wave (P = NS). While shifting the pacemaker mode from VS to VP, the E'-wave velocity (P < or =0.002) and E'/A' ratio decreased significantly (P < or = 0.001). The A'-wave velocity also increased significantly during shifting to VP mode at 60 b.p.m. (P < or =0.004). CONCLUSION: At fixed pacing rates, shifting from VS to VP mode impaired LV diastolic function immediately with preserved LV contractility. The acceleration of heart rate impaired LV diastolic function under VS mode.

Electrocardiographic alterations after chronic right ventricular apical pacing in patients with sinus node dysfunction.

OBJECTIVE: The purpose of this study is to investigate the potential to induce electrical remodeling by chronic right ventricular apical (RVA) in patients with sinus node dysfunction. METHODS: Ninety-two patients with sinus node dysfunction who underwent initial pacemaker implantation were included in the study. During routine clinic visits, electrocardiograms and echocardiograms were recorded. Forty-five patients were also studied as controls. RESULTS: During a mean follow-up time of 3.3 +/- 0.5 years, the intrinsic QRS duration increased from 87 +/- 9 milliseconds before device implantation to 94 +/- 10 milliseconds (P < .001). The left ventricular end-diastolic diameter increased from 46 +/- 3 to 50 +/- 4 mm (P < .001), and the left ventricular ejection fraction decreased from 63% +/- 4% to 57% +/- 5% (P < .001). Logistic regression analysis revealed that elderly age at the time of pacemaker implantation (odds ratio [OR], 3.41; 95% confidence interval [CI], 1.07-10.90; P = .04), RVA pacing (OR, 3.91; 95% CI, 1.10-13.89; P = .03), and coronary artery disease (OR, 7.33; 95% CI, 1.09-50.29; P = .04) were independent predictors of the prolongation of intrinsic QRS duration. CONCLUSIONS: The present study indicated that chronic RVA pacing may lead to a prolongation of intrinsic QRS duration, which could be independently predicted by elderly age, chronic RVA pacing, and the presence of coronary artery disease.

Interleukin-10 treatment attenuates sinus node dysfunction caused by streptozotocin-induced hyperglycaemia in mice.

Aims: Diabetes, characterized by hyperglycaemia, causes sinus node dysfunction (SND) in several rodent models. Interleukin (IL)-10, which is a potent anti-inflammatory cytokine, has been reported to decrease in obese and diabetic patients. We tested the hypothesis that administration of IL-10 inhibits the development of SND caused by hyperglycaemia in streptozotocin (STZ)-induced diabetic mice. Methods and results: Six-week old CL57/B6 (WT) mice were divided into the following groups: control, STZ injection, and STZ injection with systemic administration of IL-10. IL-10 knockout mice were similarly treated. STZ-induced hyperglycaemia for 8 weeks significantly depressed serum levels of IL-10, but increased several proinflammatory cytokines in WT mice. STZ-induced hyperglycaemia-reduced resting heart rate (HR), and attenuated HR response to isoproterenol in WT mice. In isolated perfused heart experiments, corrected-sinus node recovery time was prolonged in WT mice with STZ injection. Sinus node tissue isolated from the WT-STZ group showed fibrosis, abundant infiltration of macrophages, increased production of reactive oxygen species (ROS), and depressed hyperpolarization activated cyclic nucleotide-gated potassium channel 4 (HCN4). However, the changes observed in the WT-STZ group were significantly attenuated by IL-10 administration and were further exaggerated in IL-10 knockout mice. In cultured cells, preincubation of IL-10 suppressed hyperglycaemia-induced apoptotic and profibrotic signals, and overproduction of ROS. IL-10 markedly inhibited the high glucose-induced p38 activation, and activated signal transducer and activator of transcription (STAT) 3 phosphorylation. Conclusions: Our results suggest that IL-10 attenuates ROS production, inflammation and fibrosis, and plays an important role in the inhibition of hyperglycaemia-induced SND by suppression of HCN4 downregulation. In addition, IL-10-mediated inhibition of p38 is dependent on STAT3 phosphorylation.

Effects of pacing modes on cardiac baroreflex function in permanently paced patients with sinus node dysfunction.

OBJECTIVES: We compared, in patients with sick sinus syndrome, the effects of various pacing modes on baroreceptor (BR)-stroke volume (SV) reflex sensitivity, a method we have closely correlated with BR-heart rate (HR) reflex sensitivity. BACKGROUND: Impaired autonomic nervous function, such as decreased BR-HR reflex sensitivity, predicts sudden cardiac death. However, in patients with sick sinus syndrome, the effects of various pacing modes on autonomic function are unknown, since chronotropic incompetence precludes its evaluation by measurements of BR-HR reflex sensitivity. METHODS: We studied 12 recipients of dual-chamber pacemakers with sick sinus syndrome (mean age = 73 +/- 8 years; 8 men). Beat-by-beat blood pressure (BP) and SV were measured during 5-minute runs of AAI, DDD, and VVI pacing, and spectrally analyzed to assess BR-SV reflex sensitivity. RESULTS: Systolic BP was significantly lower (P < 0.01) during VVI (109 +/- 24 mmHg) than during DDD (124 +/- 22 mmHg) or AAI (125 +/- 41 mmHg) pacing. SV was significantly smaller during VVI (36 +/- 23 mL) than during DDD (49 +/- 31 mL) pacing (P < 0.05). BR-SV reflex sensitivity was significantly lower (P < 0.05) during VVI (9.3 +/- 5.7% per mmHg) than during DDD (15.0 +/- 6.5% per mmHg) or AAI (15.5 +/- 6.2% per mmHg) pacing. CONCLUSIONS: BR-SV reflex sensitivity was significantly lower during VVI than during AAI or DDD pacing. Atrioventricular synchrony plays an important role in the preservation of BR-SV reflex sensitivity in pacemaker recipients.

Reduced ejection fraction, sudden cardiac death, and heart failure death in the mode selection trial (MOST): implications for device selection in elderly patients with sinus node disease.

UNLABELLED: Sudden Cardiac Death in Elderly Pacemaker Patients. BACKGROUND: The purpose of this study was to describe the incidence and predictors of sudden cardiac death (SCD) and heart failure (HF) death, and coexisting indications for ICDs and CRT, in patients with sinus node disease (SND) treated with pacemakers. METHODS AND RESULTS: Baseline variables were used to predict SCD and HF death among 1,135 patients in the Mode Selection Trial, a 6-year trial of pacing mode in SND. There were 73 deaths among 177 patients with EF or= 50%. SCD accounted for 21.9%, 23.9%, and 14.3% of deaths with EF or= 50%. HF deaths accounted for 23.3%, 19.6%, and 3.4% of deaths with EF or= 50%. EF or= 120 ms. However, >40% died within 33 months (4-year noncardiac death rate approximately 22%). CONCLUSIONS: Reduced EF predicts SCD and HF death in SND treated with pacemakers. SCD rates among patients with EF

Atrial lead dysfunction: an unusual feature of hypothyroidism.

Hypothyroidism is known to have a multitude of cardiac electrophysiologic effects, including bradycardia, atrioventricular block, prolonged QT interval, and elevated ventricular pacing thresholds. We report the case of a 36-year-old woman who presented with isolated dysfunction of her atrial pacemaker lead, which reversed with thyroid hormone replacement.

[The influence of nitroglycerin on sinus node chronotropic response in ischemic heart disease]. / Ocena wplywu nitrogliceryny na uszkodzony chronotropizm werzla zatokowego w chorobie niedokrwiennej.

BACKGROUND: Sick sinus syndrome (SSS) is frequently observed in patients with coronary artery disease (CAD). The influence of nitrates administered in CAD on sinus node function has not been established yet. It is not yet clear whether nitrates improve the sinus node blood supply or whether they directly influence the sinus node authomaticity. The second hypothesis is seems to be supported by the results of animal studies. AIM: Evaluation of sinus node chronotropic response to the stimulation by nitric oxide (NO) donors, after pharmacological blockade in patients with different types of SSS with ischemic etiology. We studied 102 patients with suspected sinus node dysfunction and clinically diagnosed ischemic heart disease. METHODS: Test of sinus node chronotropic response was performed after pharmacological blockade with atropine and propranolol. A bolus of 100 microg nitroglycerin was administered to all patients. The following parameters were assessed: heart rate before (HR(NTG 0)), and after NTG bolus; maximal (HRNTG max) and mean at 5t second (HR(NTG 5)). Based on results of stimulation patients were divided into two groups: group I--70 patients with electrophysiological signs of SSS and group II--32 patients without the above mentioned signs. One subgroup with decreased IHR alone and three subgroups with different types of SSS were assigned from group I. RESULTS: Heart rate before (HR0) and after bolus of 100 microg nitroglycerin (HR(NTG max), HR(NTG 5)) were significantly lower in patients with SSS than in subjects with normal sinus node function. There were no significant differences of absolute and relative HR increase after NTG bolus between both groups of patients. The values of HR(NTG max) and HR(NTG 5) did not vary significantly between subgroups of patients with different types of SSS. Patients with intrinsic SSS revealed positive correlation between HR0 and both: HRmax and HR(NTG 5). whereas persons with other types of SSS did not show this relation. CONCLUSIONS: (1) Significant positive chronotropic response of sinus node to the stimulation by NO donor was observed in both patients: with and without electrophysiological signs of SSS. (2) The positive chronotropic response of sinus node to NTG bolus was observed despite of type of SSS.

Does Warden's procedure reduce sinus node dysfunction after surgery for partial anomalous pulmonary venous connection?

A best evidence topic in cardiothoracic surgery was written according to a structured protocol. The question addressed was 'Does Warden's procedure reduce sinus node dysfunction (SND) after surgery for partial anomalous pulmonary venous connection?' Altogether 101 papers were found using the reported search; of which 10 papers provided the best evidence to answer the question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes, length of follow-up and results of these studies were tabulated. There was a particular reference to Warden's procedure, avoidance of incision across the cavoatrial junction and the postoperative sinus node status. There was a direct reference to the adoption of Warden's procedure in nine studies while one study emphasized the careful use of incision across the cavoatrial junction as a way of averting postoperative SND. The evidence supports the notion that preservation of the sinus node and its blood supply through the adoption of Warden's technique results in near-absent SND during long-term follow-up. The incidence of SND ranged from 0 to 6.5% when Warden's procedure was used, increasing to 18.1% when the atrial incision was extended across the cavoatrial junction into the superior vena cava and reaching as high as 55% in double-patch repair. The study limitations include the lack of randomized controlled trial, absence of 24 h Holter monitoring in most of the patients and shorter periods of follow-up.