In 1962, a simplified method of transvenously inserting an intracardiac electrode and implanting the whole pacemaker system under local anaesthesia was reported from the Karolinska Hospital in Stockholm. This simplified method has been universally adopted and pacemakers are now probably implanted too freely in many places. In the Stockholm area pacemakers are implanted half as frequently as in the rest of Sweden and as often as in the United Kingdom.
Quadripolar left ventricular (LV) leads allow for several pacing configurations in candidates for cardiac resynchronization therapy (CRT). Whether different pacing configurations may affect LV dyssynchrony and systolic function is not completely known. We aimed to evaluate the acute effects of different pacing vectors on LV electromechanical parameters in patients implanted with a quadripolar LV lead.
In this two-centre study, within 1 month of implantation 21 CRT patients (65 ± 8 years, 76 % men, 38 % ischemic) receiving a quadripolar LV lead (Quartet 1458Q, St Jude Medical) underwent LV capture threshold assessment, intracardiac electrogram optimization, and two-dimensional echocardiography during four pacing configurations: D1-P4, P4-RV coil, D1-RV coil, and P4-M2. LV dyssynchrony and contractile function were expressed by septal-to-lateral delay and global longitudinal strain (GLS).
LV capture threshold varied between the configurations (P
OBJECTIVE: The purpose of our study was to evaluate whether repeated ventricular pacing is able to induce adaptation against ischemia in coronary artery disease patients. DESIGN: Fifteen patients with documented coronary artery disease were subjected to two successive periods of rapid ventricular pacing (150 bpm) of equal length (295+/-33 s), the first being limited by intolerable anginal pain. The second pacing period, of the same length as the first, was initiated after the disappearance of angina and ST depression, the mean resting time being 433+/-30 s. Blood samples for the determination of transcardiac differences in glucose, lactate, free fatty acids, K+, pCO2, pH, oxygen saturation and noradrenaline were taken from the femoral artery and coronary sinus before and at the end of each pacing period. The mechanical performance of the hearts was followed by continuous monitoring of intra-arterial blood pressure and pulmonary capillary wedge pressure, and the observed adaptation in the measured variables during the successive pacing tests was correlated with the duration of angina, severity of coronary artery disease and degree of collateralization. RESULTS: Changes in the transcardiac pH and K+ differences, ST segment and pulmonary capillary wedge pressure were less pronounced during the second pacing period. The subgroup with net lactate production before or after the first pacing period demonstrated metabolic adaptation manifested as improved lactate extraction during the second pacing period. Rate-pressure product and oxygen extraction, and thus presumably also overall oxygen consumption and oxygen delivery, were similar during both tests. The magnitude of adaptation did not correlate with the duration of angina, severity of coronary artery disease or overall collateral score. CONCLUSION: Rapid ventricular pacing is able to induce adaptation to myocardial ischemia, but the exact mechanisms in this process remain to be elucidated.
Division of Cardiology, Department of Medicine and Cardiovascular Research Group, Faculty of Medicine, 2C2 Walter MacKenzie Health Sciences Centre, University of Alberta, Edmonton, AB T6G 2R7, Canada. bjugdutt@ualberta.ca
The elderly population (age > or =65) is increasing and with it morbidity, hospitalizations, costs and mortality due to heart failure (HF). HF is a progressive disorder that is superimposed on an on-going aging process. The two broad categories of HF, HF with left ventricular (LV) systolic dysfunction or low ejection fraction (HF/low-EF) and HF with preserved ejection fraction (HF/PEF) are equally prevalent in the elderly. Trials of therapy for HF/low-EF in primarily non-elderly patients showed mortality benefit in elderly patients. In contrast, trials for HF/PEF have not shown mortality benefit in elderly or non-elderly patients. HF pharmacotherapy in the elderly is challenging and needs to be individualized and consider several aging-related changes. More research into the biology of aging and more clinical trials in elderly patients are needed to improve morbidity and mortality in elderly HF patients.
In patients undergoing cardiac rhythm device surgery, it is common practice to discontinue oral anticoagulation and to perform heparin bridging in order to reduce the risk of bleeding and minimize the risk of thromboembolic events.
The purpose of this study was to determine the perioperative anticoagulation strategies currently in use.
A survey presented four clinical scenarios of patients on oral anticoagulation undergoing cardiac rhythm device surgery. The scenarios represented a gradient of perceived thromboembolic risk based on the presence of atrial fibrillation, a mechanical heart valve, previous stroke, and the remainder of the CHADS(2) risk factors (congestive heart failure, hypertension, age >75 years, diabetes, previous stroke or transient ischemic attack). Respondents were offered six options that included discontinuing oral anticoagulation without heparin, three different heparin bridging protocols, and ongoing oral anticoagulation with reduced or therapeutic dose warfarin.
Based on responses from 38 (61%) of 62 electrophysiologists surveyed across Canada, 83% of respondents held warfarin without bridging in a low-risk, 78-year-old patient with atrial fibrillation (CHADS(2) score 1). In three higher-risk patient scenarios, 67% to 100% of respondents chose heparin bridging or ongoing warfarin; 38% to 72% of respondents chose heparin bridging, with 23% to 36% choosing variable use of ongoing warfarin. In all three cases where respondents indicated that they would bridge, each of the three heparin regimens was chosen by at least 20% of respondents.
There is a wide range of approaches to perioperative management in patients on oral anticoagulation undergoing cardiac rhythm device surgery. Clinical equipoise is evident and supports the need for comparative studies.
To determine the incidence and risk factors of arrhythmic complications after electrical cardioversion of acute atrial fibrillation (AF).
Our retrospective multicentre study collected data from 7660 cardioversions of acute (5 s) occurred immediately after 51 cardioversions leading to a short resuscitation in seven cases and two patients needed extrinsic pacing after the cardioversion. In nine cases, asystole was followed by bradycardia. Bradycardic ventricular rate (
Electrocardiographic (ECG) recognition of the underlying rhythm in patients with ventricular pacing can be difficult. Atrial fibrillation (AF) in particular may go unreported.
To compare the underlying atrial rhythm determined in the pacemaker clinic with the 12-lead ECG interpretation of the atrial rhythm in those who were continuously paced in the ventricle. It was intended to determine whether long term anticoagulation therapy was related to whether AF was diagnosed before or after pacemaker implantation.
Pacemaker clinic patients were enrolled if they had a 100% paced ventricular rhythm. The underlying rhythm was determined using pacemaker programming manoeuvres. A 12-lead ECG was recorded on all patients within 10 min of their pacemaker assessment and interpreted by one of the several geographic full-time cardiologists at the centre. All cardiologists were blinded to the results of pacemaker assessment and to the clinical history.
Fifty-six patients were enrolled. At the pacemaker clinic, 37 were determined to be in AF and three were in atrial flutter (AFL). Of these 40 patients with AF/AFL, 28 were correctly identified as such on the 12-lead ECG interpretation. Twelve of the 40 were interpreted only as having an 'electronic ventricular pacemaker' (EVP). Sixteen of the 40 patients (40.0%) with AF or AFL were not taking warfarin. Twenty-two of 25 patients with an AF/AFL diagnosis before pacemaker implantation were taking warfarin, compared with two of 15 patients with AF/AFL diagnosis after pacemaker implantation (P
During recent years, the exploration of different aspects of atrial fibrillation (AF) has become increasingly interesting. Thus, knowledge about basic underlying mechanisms, consequences and different modes of treatment has rapidly expanded. At a meeting in Lund, Sweden, in 1993, scientists within different fields of AF research gathered for the exchange of information. This paper is a short summary of some topics discussed at the Lund meeting and some suggestions as to how further research in this field may help to improve our understanding of this arrhythmia and the treatment of patients suffering from it. Underlying pathoelectrophysiological mechanisms in AF have been explored in experimental models in animals and by direct recordings of different atrial myocardial electrophysiological variables both in the catheter laboratory and during open heart surgery in man. Some findings illustrate possible generalized atrial myocardial mechanisms, whilst other findings clearly indicate the possibility of localized pathoelectrophysiological mechanisms. The generally accepted hypothesis that AF is perpetuated by multiple re-entry mechanisms is, thus, both verified and modified by recent studies. In addition to subjective symptoms and well identified thromboembolic consequences, accumulating evidence tells us that AF may precipitate a myocardial dysfunction which may be misinterpreted as an underlying factor initiating the arrhythmia. Today's treatment of AF includes several newer antiarrhythmic drugs, different ablation techniques, the application of different electrical devices as well as different surgical methods. New, improved and simplified methods are expected. Atrial fibrillation is the single most important supraventricular arrhythmia needing substantial further exploration of mechanisms, consequences and treatment. The Lund symposium contributed to this process by defining the state of knowledge in 1993 and outlining the need for the years to come.
Clinical Epidemiology Unit, Department of Medicine, Karolinska Institutet and Karolinska University Hospital, Site Solna M9:01, SE-171 76 Stockholm, Sweden. Michael.Fored@ki.se
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.
