Estimating Arterial Cyclic Strain from the Spacing of Endothelial Nuclei.

BACKGROUND: The non-uniform distribution of atherosclerosis within the arterial system is widely attributed to variation in haemodynamic wall shear stress. It may also depend on variation in pressure-induced stresses and strains within the arterial wall; these have been less widely investigated, at least in part because of a lack of suitable techniques. OBJECTIVES: Here we show that local arterial strain can be determined from impressions left by endothelial cells on the surface of vascular corrosion casts made at different pressures, even though only one pressure can be examined in each vessel. The pattern of pits in the cast caused by protruding endothelial nuclei was subject to "retro-deformation" to identify the pattern that would have occurred in the absence of applied stresses. METHODS: Retaining the nearest-neighbour pairs found under this condition, changes in nearest-neighbour vectors were calculated for the pattern seen in the cast, and the ratio of mean changes at different pressures determined. This approach removes errors in simple nearest-neighbour analyses caused by the nearest neighbour changing as deformation occurs. RESULTS: The accuracy, precision and robustness of the approach were validated using simulations. The method was implemented using confocal microscopy of casts of the rabbit aorta made at systolic and diastolic pressures; results agreed well with the ratio of the macroscopic dimensions of the casts. CONCLUSIONS: Applying the new technique to areas around arterial branches could support or refute the hypothesis that the development of atherosclerosis is influenced by mural strain, and the method may be applicable to other tissues.

Safety and efficacy of multipolar pulmonary vein ablation catheter vs. irrigated radiofrequency ablation for paroxysmal atrial fibrillation: a randomized multicentre trial.

AIMS: The current challenge in atrial fibrillation (AF) treatment is to develop effective, efficient, and safe ablation strategies. This randomized controlled trial assesses the medium-term efficacy of duty-cycled radiofrequency ablation via the circular pulmonary vein ablation catheter (PVAC) vs. conventional electro-anatomically guided wide-area circumferential ablation (WACA). METHODS AND RESULTS: One hundred and eighty-eight patients (mean age 62 ± 12 years, 116 M : 72 F) with paroxysmal AF were prospectively randomized to PVAC or WACA strategies and sequentially followed for 12 months. The primary endpoint was freedom from symptomatic or documented >30 s AF off medications for 7 days at 12 months post-procedure. One hundred and eighty-three patients completed 12 m follow-up. Ninety-four patients underwent PVAC PV isolation with 372 of 376 pulmonary veins (PVs) successfully isolated and all PVs isolated in 92 WACA patients. Three WACA and no PVAC patients developed tamponade. Fifty-six percent of WACA and 60% of PVAC patients were free of AF at 12 months post-procedure (P = ns) with a significant attrition rate from 77 to 78%, respectively, at 6 months. The mean procedure (140 ± 43 vs. 167 ± 42 min, P<0.0001), fluoroscopy (35 ± 16 vs. 42 ± 20 min, P<0.05) times were significantly shorter for PVAC than for WACA. Two patients developed strokes within 72 h of the procedure in the PVAC group, one possibly related directly to PVAC ablation in a high-risk patient and none in the WACA group (P = ns). Two of the 47 patients in the PVAC group who underwent repeat ablation had sub-clinical mild PV stenoses of 25-50% and 1 WACA patient developed delayed severe PV stenosis requiring venoplasty. CONCLUSION: The pulmonary vein ablation catheter is equivalent in efficacy to WACA with reduced procedural and fluoroscopy times. However, there is a risk of thrombo-embolic and pulmonary stenosis complications which needs to be addressed and prospectively monitored. CLINICALTRIALSGOV IDENTIFIER: NCT00678340.

'You can't walk through water without getting wet' UK nurses' distress and psychological health needs during the Covid-19 pandemic: A longitudinal interview study.

BACKGROUND: Pre-COVID-19 research highlighted the nursing profession worldwide as being at high risk from symptoms of burnout, post-traumatic stress disorder (PTSD) and suicide. The World Health Organization declared a pandemic on 11th March 2020 due to the sustained risk of further global spread of COVID-19. The high healthcare burden associated with COVID-19 has increased nurses' trauma and workload, thereby exacerbating pressure on an already strained workforce and causing additional psychological distress for staff. OBJECTIVES: The Impact of COVID-19 on Nurses (ICON) interview study examined the impacts of the pandemic on frontline nursing staff's psychosocial and emotional wellbeing. DESIGN: Longitudinal qualitative interview study. SETTINGS: Nurses who had completed time 1 and 2 of the ICON survey were sampled to include a range of UK work settings including acute, primary and community care and care homes. Interviewees were purposively sampled for maximum variation to cover a broad range of personal and professional factors, and experiences during the COVID-19 pandemic, including redeployment. METHODS: Nurses participated in qualitative in-depth narrative interviews after the first wave of COVID-19 in July 2020 (n = 27) and again at the beginning of the second wave in December 2020 (n = 25) via video and audio platform software. Rigorous qualitative narrative analysis was undertaken both cross-sectionally (within wave) and longitudinally (cross wave) to explore issues of consistency and change. RESULTS: The terms moral distress, compassion fatigue, burnout and PTSD describe the emotional states reported by the majority of interviewees leading many to consider leaving the profession. Causes of this identified included care delivery challenges; insufficient staff and training; PPE challenges and frustrations. Four themes were identified: (1) 'Deathscapes' and impoverished care (2) Systemic challenges and self-preservation (3) Emotional exhaustion and (4) (Un)helpful support. CONCLUSIONS: Nurses have been deeply affected by what they have experienced and report being forever altered with the impacts of COVID-19 persisting and deeply felt. There is an urgent need to tackle stigma to create a psychologically safe working environment and for a national COVID-19 nursing workforce recovery strategy to help restore nurse's well-being and demonstrate a valuing of the nursing workforce and therefore support retention.

Determining Haemodynamic Wall Shear Stress in the Rabbit Aorta In Vivo Using Contrast-Enhanced Ultrasound Image Velocimetry.

Abnormal blood flow and wall shear stress (WSS) can cause and be caused by cardiovascular disease. To date, however, no standard method has been established for mapping WSS in vivo. Here we demonstrate wide-field assessment of WSS in the rabbit abdominal aorta using contrast-enhanced ultrasound image velocimetry (UIV). Flow and WSS measurements were made independent of beam angle, curvature or branching. Measurements were validated in an in silico model of the rabbit thoracic aorta with moving walls and pulsatile flow. Mean errors over a cardiac cycle for velocity and WSS were 0.34 and 1.69%, respectively. In vivo time average WSS in a straight segment of the suprarenal aorta correlated highly with simulations (PC = 0.99) with a mean deviation of 0.29 Pa or 5.16%. To assess fundamental plausibility of the measurement, UIV WSS was compared to an analytic approximation derived from the Poiseuille equation; the discrepancy was 17%. Mapping of WSS was also demonstrated in regions of arterial branching. High time average WSS (TAWSSxz = 3.4 Pa) and oscillatory flow (OSIxz = 0.3) were observed near the origin of conduit arteries. In conclusion, we have demonstrated that contrast-enhanced UIV is capable of measuring spatiotemporal variation in flow velocity, arterial wall location and hence WSS in vivo with high accuracy over a large field of view.

The convergent procedure versus catheter ablation alone in longstanding persistent atrial fibrillation: A single centre, propensity-matched cohort study.

BACKGROUND: Maintenance of sinus rhythm is challenging in patients with longstanding persistent atrial fibrillation (PeAF). Minimally invasive surgical AF ablation may improve outcomes when combined with catheter ablation (the 'convergent' procedure). This study evaluates the safety and efficacy of the convergent procedure versus catheter ablation alone in longstanding PeAF. METHODS: 43 consecutive patients with longstanding PeAF underwent subxiphoid endoscopic ablation of the posterior left atrium followed by catheter ablation from 2013 to 2018. The primary outcome was AF-free survival at 12 months; secondary outcomes included change in EHRA class, echocardiographic data, procedural complications, freedom from anti-arrhythmic drugs (AADs), and long term arrhythmia-free survival. Outcomes were compared with a matched group of 43 patients who underwent catheter ablation alone. Both groups underwent multiple catheter ablations as required. Baseline characteristics were similar between groups. RESULTS: After 12 months, the convergent procedure was associated with increased AF-free survival on AADs (60.5% versus 25.6%, p = .002) and off AADs (37.2% versus 13.9%, p = .025), versus catheter ablation. Allowing for multiple procedures, after 30.5 ±â€¯13.3 months' follow-up the convergent procedure was associated with increased arrhythmia-free survival on AADs (58.1% versus 30.2%, p = .016) and off AADs (32.5% versus 11.6%, p = .036) versus catheter ablation. There were more complications in the convergent procedure group (11.6% versus 2.3%, p = .2). Multivariate analysis identified only the convergent procedure (OR 3.06 (1.23-7.6), p = .017) as predictive of arrhythmia-free survival long term. CONCLUSIONS: In longstanding PeAF, the convergent procedure is associated with improved arrhythmia-free survival versus catheter ablation alone. Complication rates are significant but have been shown to depreciate with experience.

Initial experience with the convergent procedure for longstanding persistent atrial fibrillation: A 5 year dataset.

In patients with longstanding persistent atrial fibrillation (AF), outcomes from catheter ablation remain suboptimal. The convergent procedure combines minimally invasive surgical ablation with subsequent catheter ablation, and may contribute towards maintenance of sinus rhythm in this patient group. We performed the convergent procedure on 43 patients with longstanding persistent AF from 2013-2018. Patients underwent clinical review at 3, 6, and 12 months and thereafter as necessitated by their symptoms. Our dataset describes patients' baseline characteristics and rhythm control protocols, as well as outcomes including arrhythmia recurrence, the need for antiarrhythmic drugs, requirement for repeat rhythm control procedures, and complications. These data provide a real world insight into the risks and benefits of the convergent procedure in patients with longstanding persistent AF.

A dataset of customer loyalty and variation in perception of customers across demographic characteristics In healthcare sector of Nigeria.

The data depicted on customer loyalty in the healthcare sector was concentrated on the variation in perception across demographic characteristics on the subject matter. The data focused on selected private hospitals adjudged to be the best four in Lagos State, Nigeria. In this data article, the variables for customer loyalty were categorized into (repeat purchase, brand insistence, switching restraint and customer satisfaction) for healthcare service sector in Nigeria. The data made used of the personal profile of the respondents as the independent variables to establish a link between the aims of the study and the demographic characteristics via the quantitative method. Data were gathered from 365 respondents through the use of structured questionnaire. The Kruskal Wallis Test was carried out to investigate and identify what accounted for the variation in the customers' perception on the subject matter. The SPSS (22) was utilized to analysed the data. This dataset is presented openly for easy accessibility for a greater critical examination.

Survey data on employees' perception of the impact of community development initiatives on the corporate image of oil and gas firms in Nigeria.

Several sources of today׳s pressure on managers in strategic decision-making are directly associated with social issues rather than traditional strategic management issues. It is believed that firms that invest in community development are more likely to operate in harmony in the society of their operations, as such reduce interference from their host community, thus leading to enhanced corporate image. Therefore, it becomes pertinent to present data to show the existence or otherwise of a relationship between community development initiatives and the firm׳s corporate image. This data is gotten from 336 respondents from four top oil and gas firms quoted in the Nigerian stock exchange. Responses wee gathered from the employees' of the firms, as it is believed they have first hand information on the firm׳s corporate social responsibility policies. The data is purely descriptive and was gotten through quantitative methods, specifically through a survey questionnaire. The questionnaire had two sections; section A contained background questions, while section B consisted of questions that were specific to community development initiatives and corporate image. The Cronbach alpha internal consistency of the questionnaire revealed a reliability coefficient of 0.732, thus revealing a high consistency level. The field data set is made widely accessible to enable critical investigation into the subject.

Dataset on humanic clues and customer loyalty in selected hospitals in Lagos State, Nigeria.

This article describes survey result on humanic clues and customer loyalty in selected hospitals in Lagos State, Nigeria. This paper obtains information from the customer experience management strategy in considering the techniques in which customer loyalty can be built. 365 copies of questionnaires were retrieved from the customers of the selected four private hospitals in Lagos State. The data gathered from the survey customers were subjected to inferential and descriptive statistics in order to ascertain the sum, mean, standard deviation and the relative importance index (RII). The retrieved copies of questionnaires were analysed utilising SPSS (22). Using the Categorical Regression CATREG analysis, the data article establish that humanic clues have positive influence on customer loyalty. The data collected is openly presented to enhance further analysis.

Survey data on employees' development and employees' satisfaction in oil and gas firms in Nigeria.

Employees' development involves ensuring that employees are compensated fairly, are not exposed to dangerous or environmentally unhealthy working environment and are treated ethically in the workplace, especially in a technology intense industry as that of the oil and gas sector. Thus, this article presents data on the effect of employees' development on employees' satisfaction. The study employed a descriptive quantitative research design engaging survey method. The study population consists of 1748 employees from four top oil and gas firms quoted in the Nigerian stock exchange. A sample size of 350 employees was selected. Data was analysed using statistical Package for Social Sciences (SPSS). Regression analysis was employed as the statistical tool of analysis. The field data set is made widely accessible in this article.

Familial Hypertrophic cardiomyopathy with Wolff-Parkinson-White syndrome maps to a locus on chromosome 7q3.

We have mapped a disease locus for Wolff-Parkinson-White syndrome (WPW) and familial hypertrophic cardiomyopathy (FHC) segregating in a large kindred to chromosome 7 band q3. Although WPW syndrome and FHC have been observed in members of the same family in prior studies, the relationship between these two diseases has remained enigmatic. A large family with 25 surviving individuals who are affected by one or both of these conditions was studied. The disease locus is closely linked to loci D7S688, D7S505, and D7S483 (maximum two point LOD score at D7S505 was 7.80 at theta = 0). While four different FHC loci have been described this is the first locus that can be mutated to cause both WPW and/or FHC.

A propensity matched case-control study comparing efficacy, safety and costs of the subcutaneous vs. transvenous implantable cardioverter defibrillator.

BACKGROUND: Subcutaneous implantable cardioverter defibrillators (S-ICD) have become more widely available. However, comparisons with conventional transvenous ICDs (TV-ICD) are scarce. METHODS: We conducted a propensity matched case-control study including all patients that underwent S-ICD implantation over a five-year period in a single tertiary centre. Controls consisted of all TV-ICD implant patients over a contemporary time period excluding those with pacing indication, biventricular pacemakers and those with sustained monomorphic ventricular tachycardia requiring anti-tachycardia pacing. Data was collected on device-related complications and mortality rates. A cost efficacy analysis was performed. RESULTS: Sixty-nine S-ICD cases were propensity matched to 69 TV-ICD controls. During a mean follow-up of 31±19 (S-ICD) and 32±21months (TV-ICD; p=0.88) there was a higher rate of device-related complications in the TV-ICD group predominantly accounted for by lead failures (n=20, 29% vs. n=6, 9%; p=0.004). The total mean cost for each group, including the complication-related costs was £9967±4511 ($13,639±6173) and £12,601±1786 ($17,243±2444) in the TV-ICD and S-ICD groups respectively (p=0.0001). Even though more expensive S-ICD was associated with a relative risk reduction of device-related complication of 70% with a HR of 0.30 (95%CI 0.12-0.76; p=0.01) compared to TV-ICDs. CONCLUSIONS: TV-ICDs are associated with increased device-related complication rates compared to a propensity matched S-ICD group during a similar follow-up period. Despite the existing significant difference in unit cost of the S-ICD, overall S-ICD costs may be mitigated versus TV-ICDs over a longer follow-up period.

Clinical value of calcium antagonists in treatment of cardiovascular disorders.

All calcium antagonists have the ability to decrease the symptoms and signs in some patients with ischemic heart disease and help lower the blood pressure in hypertensive persons, but in clinical doses nifedipine does not exhibit antiarrhythmic properties, although these are an important part of the action of verapamil, diltiazem and some substances with a similar chemical structure. In certain disorders beta-adrenergic blocking drugs are useful adjuncts, and under some circumstances, particularly variant angina and supraventricular arrhythmias, specific calcium antagonists are the drugs of choice. More data are needed to define the role of calcium antagonists during cardiopulmonary bypass, in the protection of the ischemic myocardium, in the management of hypertrophic cardiomyopathy and in specific cases of primary pulmonary hypertension. When used with an appropriate sense of perspective and careful observation, calcium antagonists provide useful additional means of helping selected patients suffering from particular cardiovascular diseases.

Circadian variation of malignant ventricular arrhythmias in patients with ischemic and nonischemic heart disease after cardioverter defibrillator implantation. European 7219 Jewel Investigators.

OBJECTIVES: The purpose of this study was to examine the circadian variation of ventricular arrhythmias detected by an implantable cardioverter defibrillator in patients with and without ischemic heart disease. BACKGROUND: Previous studies have shown a circadian variation of ventricular arrhythmias, sudden death and myocardial infarction with a peak occurrence in the morning hours. The circadian pattern, which is similar for both arrhythmic and ischemic events, suggests that ischemia may play a critical role in the genesis of ventricular arrhythmias and sudden death. We hypothesized that, if ischemia plays an important role in the triggering of ventricular arrhythmias, the circadian pattern should be different in patients with ischemic heart disease compared with patients with nonischemic heart disease. METHODS: The circadian variation of ventricular arrhythmias recorded by an implantable cardioverter defibrillator was studied in 310 patients during a mean follow-up of 181 +/- 163 days. Two hundred four patients had a history of ischemic heart disease and 106 patients had nonischemic heart disease. The times of the episodes of ventricular arrhythmias were retrieved from the data log of each device during follow-up, and the circadian pattern was compared between the two groups. RESULTS: During follow-up, 1,061 episodes of ventricular arrhythmias were recorded by the device in the 310 patients. Six hundred eighty-two episodes occurred in the group of patients with ischemic heart disease and 379 occurred in the nonischemic heart disease group. The circadian variation of the episodes showed a typical pattern with a morning and afternoon peak in both groups of patients with ischemic and nonischemic heart disease, but there was no significant difference between the two groups. CONCLUSIONS: The circadian rhythm of ventricular arrhythmias in patients with ischemic heart disease is similar to patients with nonischemic heart disease, suggesting that the trigger mechanisms of the initiation of ventricular tachyarrhythmias may be similar, irrespective of the underlying heart disease.

Dispersion of monophasic action potential duration: demonstrable in humans after premature ventricular extrastimulation but not in steady state.

Abnormal dispersion of repolarization may contribute to the arrhythmogenic physiologic substrate of ventricular arrhythmia. Geographic dispersion of monophasic action potential duration was determined in steady state (drive cycle lengths 600 and 430 ms) between widely spaced right ventricular endocardial sites (geographic dispersion) in 10 control patients with right ventricular disease and complicating ventricular tachycardia (n = 9), 6 patients with right and left ventricular disease and complicating ventricular tachycardia and 7 patients with ischemic heart disease and complicating ventricular tachycardia. No significant difference in geographic dispersion could be demonstrated among the groups. Difference of monophasic action potential duration at adjacent right ventricular endocardial sites (adjacent dispersion) was determined after ventricular extrastimulation during construction of simultaneous electrical restitution curves in the same patient groups. Maximal adjacent dispersion over the electrical restitution curve was compared between disease and control groups. There was a significant difference in observations of maximal adjacent dispersion in patients with right ventricular disease and complicating ventricular tachycardia (range 5 to 85 ms, median 22.5; 14 pairs of sites; p less than 0.05) and patients with right and left ventricular disease and complicating ventricular tachycardia (range 5 to 50 ms, median 17.5; 14 pairs of sites; p less than 0.05) compared with control patients (range 5 to 20 ms, median 10; 15 pairs of sites). This difference was not evident when patients with ischemic heart disease and complicating ventricular tachycardia (range 5 to 25 ms, median 12.5; 12 pairs of sites) were compared with control patients. Maximal percent monophasic action potential shortening from steady state was significantly greater (p less than 0.001) in both groups with greater adjacent dispersions, and prolongation of activation time at monophasic action potential recording sites after premature extrastimulation tended to be greater in patients with right or right and left ventricular disease and complicating ventricular tachycardia. It is concluded that in disease, exaggeration of monophasic action potential shortening after premature ventricular extrastimulation may contribute to the electrophysiologic arrhythmogenic substrate.

Clinical anatomy of the atrioventricular junctions.

OBJECTIVES: This study reevaluated the anatomy of the areas anterior and posterior to the atrioventricular (AV) septal structures, previously said to represent anterior and posterior septal areas. BACKGROUND: In descriptions of the locations of accessory AV pathways within the AV junctions, four regions have been recognized: the left and right free walls and the anterior and posterior septums. On the basis of known facts concerning cardiac structure, it is questionable whether these so-called septums are truly septal. METHODS: Ten human hearts were dissected to elucidate the clinical anatomy of these purportedly septal regions, together with the overall arrangement of the AV junctions. RESULTS: The true septal components of the AV junctions are the muscular and membranous AV septal areas. These separate the cavity of the right atrium from that of the left ventricle. The region previously designated as the anterior septum is part of the right parietal junction. It is contiguous with the membranous part of the septum but extends anteriorly and laterally from the septum as part of the supraventricular crest of the right ventricle ("crista supraventricularis"). In the region posterior to and beneath the mouth of the coronary sinus, only the most anterior extent, in continuity with the central fibrous body, is part of the muscular AV septum. The posterior extent of this area roofs over the diverging right and left ventricular walls and is filled in with fibroareolar tissue of the AV groove. CONCLUSIONS: The larger part of the regions anterior and posterior to the true AV septal areas are not septal but are parts of the parietal AV junctions. An understanding of these anatomic relations is essential for those wishing to modify conduction across the AV junctions.

Efficacy and tolerability of transvenous low energy cardioversion of paroxysmal atrial fibrillation in humans.

OBJECTIVES: This study investigated the efficacy and tolerability of low energy shocks for termination of atrial fibrillation in patients, using an endocardial electrode configuration that embraced both atria. BACKGROUND: In animals, low energy biphasic shocks delivered between electrodes in the coronary sinus and right atrium have effectively terminated atrial fibrillation. If human defibrillation thresholds are sufficiently low, atrial defibrillation could be achieved in conscious patients using an implanted device. METHODS: Twenty-two consecutive patients with stable atrial fibrillation were studied during electrophysiologic testing. Biphasic R wave synchronous shocks were delivered between large surface area electrodes in the coronary sinus and high right atrium, using a step-up voltage protocol starting at 10 or 20 V and increasing to a maximum of 400 V. Patients were conscious at the start of the study and were asked to report on symptoms but were sedated later if shocks were not tolerated. RESULTS: Cardioversion was achieved in all 19 patients who completed the study, with a mean (+/- SD) leading-edge voltage of 237 +/- 55 V (range 140 to 340) and mean energy of 2.16 +/- 1.02 J (range 0.7 to 4.4). The mean maximal shock delivered without sedation was 116 +/- 51 V (range 60 to 180). No proarrhythmia or mechanical complications occurred. CONCLUSIONS: The delivery of biphasic R wave synchronous shocks between the high right atrium and coronary sinus can terminate atrial fibrillation with very low energies. General anaesthesia is not required, and a minority of fully conscious patients are able to tolerate this method of cardioversion.

Survival after cardiac arrest or sustained ventricular tachycardia in patients with hypertrophic cardiomyopathy.

OBJECTIVES: The aim of this study was to evaluate the survival of patients with hypertrophic cardiomyopathy (HCM) after resuscitated ventricular fibrillation or syncopal sustained ventricular tachycardia (VT/VF) when treated with low dose amiodarone or implantable cardioverter defibrillators (ICDs). BACKGROUND: Prospective data on clinical outcome in patients with HCM who survive a cardiac arrest are limited, but studies conducted before the widespread use of amiodarone and/or ICD therapy suggest that over a third die within seven years from sudden cardiac death or progressive heart failure. METHODS: Sixteen HCM patients with a history of VT/VF (nine male, age at VT/VF 19 +/- 8 years [range 10 to 36]) were studied. Syncopal sustained ventricular tachycardia/ventricular fibrillation occurred during or immediately after exertion in eight patients and was the initial presentation in eight. One patient had disabling neurologic deficit after VT/VF. Before VT/VF, two patients had angina, four had syncope and six had a family history of premature sudden cardiac death. After VT/VF all patients were in New York Heart Association class I or II, three had nonsustained VT during ambulatory electrocardiography and 11 had an abnormal exercise blood pressure response. After VT/VF eight patients were treated with low dose amiodarone and six received an ICD. Prophylactic therapy was declined by two patients. RESULTS: Mean follow-up was 6.1 +/- 4.0 years (range 0.5 to 14.5). Cumulative survival (death or ICD discharge) for the entire cohort was 59% at five years (95% confidence interval: 33% to 84%). Thirteen (81%) patients were alive at last follow-up. Two patients died suddenly while taking low dose amiodarone, and one died due to neurologic complications of his initial cardiac arrest. Three patients had one or more appropriate ICD discharges during follow-up; the times to first shock after ICD implantation were 23, 197 and 1,124 days. CONCLUSIONS: This study shows that patients with HCM who survive an episode of VT/VF remain at risk for a recurrent event. Implantable cardioverter defibrillator therapy appears to offer the best potential benefit regarding outcome.

Local abnormalities of right ventricular depolarization after repair of tetralogy of Fallot: a basis for ventricular arrhythmia.

Ventricular arrhythmia is common after repair of tetralogy of Fallot (TF) and may cause sudden death. To explore the mechanisms, ambulatory electrocardiographic monitoring and electrophysiologic studies were undertaken, without the use of provocative tests, in 22 patients 5 to 24 years (mean 13) after repair. His-Purkinje and right ventricular (RV) apical activation times were measured to assess conduction. Endocardial mapping of the right ventricle was performed, with additional recordings from the left ventricle in 10 patients, to detect abnormalities of local depolarization and repolarization. Local RV electrograms were fractionated or delayed in 12 patients (55%) at 1 or more RV sites (septum in 7 patients, outflow in 7, free wall in 2 and apex 1 patient), reflecting disordered depolarization, but left ventricular recordings were normal in all. Ventricular arrhythmia out of hospital was more common (p less than 0.05) and more severe (p less than 0.01) in the patients with depolarization abnormalities than in those with normal electrographic findings. In contrast, there was no association between ventricular arrhythmia and conduction disturbances. Abnormalities of RV repolarization, consisting of low-frequency signals after the T wave, were observed in 17 patients (77%), but were not associated with arrhythmia. Thus, ventricular arrhythmia during daily life was associated with fractionated depolarization at multiple sites in the right ventricle. This suggests that there are widespread areas of RV myocardial damage that provide substrates for ventricular tachycardia.