Reviews of clinical practice for paediatric pacemaker implantation and follow-up are necessary to provide an evidence-base for future policy and practice in this field. Epicardial pacing data available through Green Lane Hospital, New Zealand's (NZ) primary referral centre for paediatric cardiac surgery and pacemaker implantation, was reviewed with the following aims: Assessment of pacemaker lead performance over time in relation to the type of epicardial lead implanted - steroid-eluting (SE) and non steroid-eluting (NSE). Determination of the survival rate of epicardial leads. Identifying factors predicting or associated with lead failure.A database of pacing and sensing thresholds and lead impedance data at implant, 2, 6 and 18 weeks and 6 monthly intervals thereafter, was compiled and the prevalence and timing of complications in relation to lead type, location and implant route determined. In total 192 leads (155 SE, 37 NSE) were implanted in 96 patients (52 male) aged 3 days to 71 years (y) (median 1.7y), 74 patients were < 17 years of age at implant. Congenital heart defects were present in 82% of patients. Follow-up (f/u) was possible for 180 leads. Mean f/u duration for the 150 SE leads was 3.1y (2 weeks - 8.8y) and for the 30 NSE leads was 4.5y (2 weeks - 27y).SE and NSE pacing thresholds were similar at implant. NSE pacing thresholds peaked at 6 weeks post implant and remained significantly higher than SE leads throughout f/u in surviving leads, although the difference was small at 2 and 4 y. SE and NSE leads had similar ventricular sensing thresholds and lead impedances throughout the study period.Survival at 5 years for all leads was 61% (66% for SE leads and 41% for NSE leads). Primary causes of failure in the leads receiving f/u were exit block and lead fracture. The occurrence of exit block was significantly higher (p<0.0001) in NSE leads (57%) compared to SE leads (5%). Lead fracture occurred in 15% of leads with the highest fracture rate at 2-3 y post implant. Patient age and weight at implant, gender, previous cardiac surgery, lead polarity, indication for pacing and implant route were not predictors of lead failure. NSE leads were 6 times more likely to fail compared to SE leads (p <0.0001).The main study findings were: SE leads maintain lower pacing thresholds and a reduced incidence of exit block compared to NSE leads. It is therefore recommended that SE leads be developed which can penetrate fibrosed, scarred or fatty epicardial surfaces. Where SE lead use is contraindicated, alternative surgical techniques for SE lead placement should be attempted rather than implanting NSE leads. Lead fracture is a significant complication of epicardial pacing in paediatric patients. Using stronger bipolar leads implanted by the subxiphoid route may reduce the risk of fracture. Medium term survival (5 y) of SE epicardial leads is acceptable and therefore the continued use of these leads is recommended, particularly in young patients, allowing their veins to be saved for transvenous leads later in their life.

No description available.

Thesis (M.S.)--University of Wisconsin--Madison, 1985. / Typescript (photocopy). eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 168-174).

The effect of CRT on incidence of AF development in patients with severe HF was explored by comparing 36 patients with conventional indication for the CRT to 36 HF patients without CRT, matched for age, sex and LV systolic function (Publication 5). After a follow up of 3 years, the annual incidence of AF in the CRT group was 2.8%, which was significantly lower than the control group (10.2%). Moreover, the echocardiographic benefit by CRT was compared between these 36 patients with SR and 15 patients with persistent AF. The results showed that the echocardiographic response was similar between the two groups. These findings suggested that CRT may have the potential to reduce AF burden in patients with severe HF and that patients with persistent AF may also benefit from CRT. / The objective of the study (Publication 1) was to assess the feasibility of using non-contact LV mapping to delineate the LV endocardial activation pattern in 7 HF patients in NYHA class III, with low LVEF and wide QRS complex (>120ms). Non-contact mapping was safely performed and there were two endocardial conduction patterns identified, namely homogenous (Type I) and conduction block (Type II). The second part of the study (Publication 2) was to determine the implication of these two distinct activation patterns to echocardiographic and clinical response to CRT. 23 patients in NYHA class III, with LVEF &lt;35% and QRS duration >120ms were recruited in this study. 15 patients had Type II pattern and 8 Type I. The QRS duration between the two types of conduction patterns were comparable. Patients with Type II pattern had a more favourable echocardiographic and clinical response to CRT than those with Type I. It was concluded that, despite the similar QRS duration between the two types of LV endocardial activation patterns, patients with Type II pattern had a more favourable response to CRT. / The significance of baseline renal function in CRT was assessed in 85 consecutive patients with conventional indication for the CRT (Publication 7). There was no significant relationship between baseline renal function and significant LV reverse remodeling after CRT, suggesting baseline renal insufficiency probably would not affect the response to CRT. (Abstract shortened by UMI.) / This study (Publication 3) was to determine the effect of CRT in patients with narrow QRS complex and evidence of mechanical dyssynchrony as determined by TDI. 51 patients in NYHA class III or IV, with LV ejection fraction &lt;35%, and QRS duration &lt;120ms were recruited for the CRT. The effect of the device therapy on LV systolic function in this cohort was compared to 51 patients who fulfilled the current criteria with wide QRS complex. CRT significantly improved the LV systolic function, NYHA class and exercise capacity in those with narrow complex to a similar extent in those with wide complex. With co-existing mechanical dyssynchrony determined by TDI, patients in both narrow and wide QRS complex groups showed more favourable response to CRT than those without significant mechanical dyssynchrony. This confirmed that QRS was a poor marker of mechanical dyssynchrony and the current selection criteria are probably not adequate to include more potential responders to the therapy. / This study (Publication 4) was to determine the role of optimal medical therapy in CRT recipients before implantation. The echocardiographic and clinical effect of CRT in 30 patients without the optimal combination of ACEi or ARB and beta-blockers was compared to 30 patients matched for age, sex, NYHA class and HF etiology. Patients with optimal medical therapy had significantly better echocardiographic and clinical response to CRT. The results confirmed that optimal medical therapy is necessary to achieve maximal response by CRT. / This study (Publication 6) was to determine if patients with moderate LV systolic function and wide QRS complex would benefit from the CRT. Significant improvement in LV systolic function was observed in 15 patients with LVEF between 35 and 45%, NYHA class III and QRS duration >120ms after CRT, suggesting that presence of LV systolic dysfunction and cardiac dyssynchrony may be the major determining factors for favourable CRT response. Therefore, patients with less advanced HF may also benefit from the CRT. / "May 2007." / Adviser: Yu Cheuk Man. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4657. / Thesis (M.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 133-151). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / School code: 1307.

Familial amyloidosis with polyneuropathy (FAP) is a neuropathic form of heredofamilial systemic amyloidosis. Clusters of patients have been reported predominantly from Portugal, Japan and Sweden. The present study examines the involvement of the heart in individuals with the Swedish variety of FAP. During long-term ECG recording in 16 patients, a high frequency of disturbances of sinus node function and atrioventricular conduction were observed. Long-term ECG may help considerably in the evaluation of symptoms attributable to disturbances of heart rhythm in FAP. A retrospective survey of 20 patients with FAP treated with a pacemaker showed that the indication for pacing was advanced atrioventricular block (12 cases), dysfunction of the sinus node (5 cases), and atrial fibrillation with a slow ventricular response (3 cases). All patients experienced the effective relief of symptoms attributable to a slow ventricular rate. The long-term prognosis, however, seemed unaffected by this treatment. Histopathological examination of the sinoatrial (9 cases) and atrioventricular (6 cases) parts of the conduction system showed marked amyloid infiltration in all cases, which may explain the high occurrence of disturbances of cardiac rhythm and conduction. Twelve patients were examined by two-dimensional echocardiography and changes of varying degrees, such as highly refractile myocardial echoes (12 cases) and thickened ventricular walls (8 cases) and valves (7 cases), could be observed. Technetium-99m-pyrophosphate scintigraphy of the same patients revealed abnormal myocardial uptake of the isotope only in four. Echocardiography thus seems to be superior to scintigraphy for non-invasive detection of cardiac involvement in FAP. Myocardial samples from regions producing highly refractile myocardial echoes were obtained at in vitro échocardiographie examination of hearts from FAP autopsy cases. Histological examination showed that the highly refractile echoes corresponded to more or less sharply delineated nodules, containing amyloid and collagen in various amounts. / digitalisering@umu

Thesis (Ph. D.)--University of Alabama at Birmingham, 2006. / Description based on information viewed Oct. 3, 2006; title from title screen. Includes bibliographical references (p. 87-90).

When excitable cardiac tissue is electrically paced at a sufficiently high rate, the duration of excitation can alternate from beat to beat despite a constant stimulation period. This rhythm, known as alternans, has been identified as an early stage in a sequence of increasingly complex instabilities leading to the lethal arrhythmia ventricular fibrillation (VF). This connection served as as a motivation for research into the control of alternans as a strategy to prevent VF. Control methods that do not use a model of the dynamics have been used for the suppression of alternans. However, these methods possess limitations. In this thesis we study theoretically model-based control techniques with the goal of developing protocols that would overcome the shortcomings of non model-based approaches. We consider one dimensional tissue in two different geometrical configurations: a ring and a fiber with free ends (open fiber). We apply standard control methods for linear time invariant systems to a stroboscopic map of the linearized dynamics around the normal rhythm. We found that, in the ring geometry, model-based control is able to suppress alternans faster and with lower current, thereby reducing the risk of tissue damage, compared with non-model-based control. In the open fiber, model-based control is able to suppress alternans for longer fibers and higher pacing frequencies in comparison with non-model-based control. The methodology presented here can be extended to two- and three-dimensional tissue, and could eventually lead to the suppression of alternans on the entire ventricles.

published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Medical Sciences

Diss. (sammanfattning) Stockholm : Tekn. högsk. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karol. inst., 2002. / Härtill 6 uppsatser.