Delayed adaptation of ventricular repolarization after sudden changes in heart rate due to conversion of atrial fibrillation. A potential risk factor for proarrhythmia?

AIMS

Onset and termination of atrial fibrillation are often associated with abrupt changes in heart rate. Presence and time-course of delayed adaptation of the QT/QTc interval are unknown, but a temporary "mismatch" between rate and the QT interval may enhance the risk of proarrhythmia.

METHODS

In a prospective two-part study, time-course of adaptation of ventricular repolarization after abrupt changes in heart rate was assessed during termination of Holter ECG-documented atrial fibrillation episodes (Group 1, 32 patients) and subsequently in 20 patients with sick sinus syndrome and cardiac pacing initiating abrupt bi-directional changes in paced heart rate (Group 2).

RESULTS

Conversion of atrial fibrillation showed a 32+/-21 bpm fall in heart rate (P<0.05). Restoration of the QTc interval afterwards was delayed by < or =1 min in 27%, by 1-2 min in 21%, by 2-5 min in 11% and by >5 min in 41% of the cases. Atrial pacing simulating a 30 bpm fall/increase in atrial rate demonstrated that a subsequent transient rate-QT mismatch is a physiological phenomenon (fall of 100 to 70 bpm: initially 90% of the proper QTc interval, compared with 94% after conversion of atrial fibrillation). The restoration curve of QTc adaptation showed an initially fast and subsequently slower time component, with interindividual variation. Clinical parameters, baseline heart rate or the direction of rate changes were not predictive.

CONCLUSION

Delayed adaptation of ventricular repolarization following atrial fibrillation onset and termination is common, requiring minutes for restoring the QT/QTc steady state. Clinical parameters fail to predict patients with a long-lasting rate-QT mismatch. It may carry a significant arrhythmogenic risk particularly in patients on QT altering medication.

High-grade Atrioventricular Block Triggered by Spontaneous and Stimulation-induced Epileptic Activity in the Left Temporal Lobe

Cardiac bradyarrhythmias may play a pivotal role in the pathophysiology of sudden unexpected death in epilepsy (SUDEP). We describe a patient with left temporal lobe epilepsy in whom high-grade atrioventricular conduction blocks were triggered by both spontaneous and stimulation-induced epileptic activity in the left temporal lobe. Electrophysiological data obtained by surface and intracranial electrodes point to a cerebral cardioarrhythmogenesis in the left amygdala and anterior hippocampus.

Herzrhythmusst�rungen und pl�tzlicher Herztod bei Frauen

BACKGROUND

Gender specific cardiac arrhythmias have been recognized for more than 80 years. The impact of gonadal steroids on the autonomic system and on the cellular electrophysiology of the cardiac autonomic system are discussed as is a direct genetic disposition on a cellular, functional or metabolic level. We nevertheless have to be aware of age- and gender-specific differences of heart diseases, which have an impact on the incidence, form and severity of cardiac arrhythmias.

CARDIAC ARRHYTHMIAS IN WOMEN

Gender-specific electrophysiologic differences like a higher basic heart rate and a longer QT-interval, beginning after puberty, are the main changes in ECGs in women and have a strong relationship to constitutional and hormonal influences. Supraventricular arrhythmias, i. e. in women sinus and AV-nodal-reentry tachycardias, less frequently Wolff-Parkinson-White tachycardias, may show clearly cyclical differences. Atrial fibrillation is more frequent in women, is more symptomatic, and there are more problems in therapy. Ventricular arrhythmias, occurring equally in healthy persons, show a strong relationship to coronary artery disease in men, which is less significant in women (in women more arrhythmogenic co-factors). Women suffer from acquired and congenital long-QT syndrome, and consequently more often from torsade-de-pointes tachycardias (stronger drug-induced QT-lengthening, more short-long sequences, differences in Ikr sensitivity). Sudden cardiac death is three times more often in men. Women suffer from it about ten years later; it is a more heterogenous phenomenon than in men, and the prognosis is worse. Women are underrepresented in controlled studies for primary and secondary prevention compared to men.

CONCLUSIONS

As the underlying reasons of gender-specific differences in cardiac arrhythmias are not known in detail, the findings discussed imply the necessity of more basic studies to evaluate gender-specific solutions for risk stratification and therapy.

Long-term survival after pacemaker implantation. Prognostic importance of gender and baseline patient characteristics

Permanent cardiac pacing is the treatment of choice in severe and symptomatic bradycardia. To determine factors associated with longer survival we analysed the survival times and baseline characteristics of 6505 patients after pacemaker implantation. This longitudinal study with 30 years of follow-up was performed in a single centre university hospital with all-cause mortality as the end-point. In 6505 patients we analysed a total of 30948 years of patient follow-up, median survival was 101.9 months ( approximately 8.5 years), with 44.8% of patients alive after 10 years and 21.4% alive after 20 years. In all subgroups women had a significantly longer survival than men (118 vs 91.7 months, P<0.0001), despite a markedly higher age at implantation (73.2 years vs 71 years, P<0.0001). Survival of patients with sick-sinus-syndrome was significantly better than in patients with high degree AV-block, which in turn, was better than survival of patients with atrial fibrillation (132.9 months vs 94.2 months vs 85.1 months, P<0.0001). Multivariate analysis revealed several independent factors: age, gender, decade of implantation, type of pacemaker, index arrhythmia and initial symptoms. Interestingly, if only the patients of the last decade were analysed multivariately, neither pacing mode nor index arrhythmia were independently associated with survival. In conclusion, survival of patients with pacemakers is independently influenced by several baseline characteristics which can identify patients with very long survival.

Pacemaker therapy in very elderly patients: long-term survival and prognostic parameters

BACKGROUND

Permanent pacing is the therapy of choice for treating severe and/or symptomatic bradyarrhythmia. However, augmented life expectancy and increasing health care expenditures have led to questions concerning the routine use of electrotherapy in very elderly patients. This study is aimed at assessing data on the actual number, characteristics, and survival of patients requiring pacing therapy at age > or =80 years.

METHODS

Between 1971 and 2000, 1588 patients aged > or =80 years completed a standardized 6- to 12-month follow-up after pacemaker (PM) implantation, resulting in a total of 5244 patient years. Kaplan-Meier analyses were computed to visualize survival differences in various subgroups and implantation periods.

RESULTS

Today, patients aged > or =80 years account for 32% of all PM implantations. An increasing 5-year survival after PM implantation to the current rate of 66% was found, compared to 37% and 47% in the previous decades. Based on a mean survival time of 8 years, clinical symptoms can be effectively treated with costs of < or =500 dollars per patient per year. Prognostic parameters were the decade of implantation (relative risk [RR] 0.80, CI 0.67-0.96, P < or =.02), a history of presyncope (RR 0.73, CI 0.57-0.95, P < or =.02), and male sex (RR 1.20, CI 1.04-1.40, P < or =.02). However, none of these parameters can be recommended for estimating outcome or for guiding device selection.

CONCLUSIONS

Patients aged > or =80 years account for an increasing portion of PM implantations. Considering the remaining life expectancy of 8 years in these patients, PM therapy is a clinically and economically effective therapeutic option to control bradyarrhythmia-related symptoms.

A unique pacemaker complication of thrombus formation in the right internal jugular vein due to unusual migration of an atrial pacemaker electrode

Our report describes the late migration of an atrial screw-in lead into the right internal jugular vein causing subsequent subclinical thrombus formation at the tip of the electrode. Previously initiated anticoagulation for atrial fibrillation may have prevented complete occlusion of the internal jugular vein. Therefore, prophylactic anticoagulation should be considered for patients in whom permanent pacing leads are dislodged into central veins and cannot be removed.

A technical approach to optimized atrial recognition in the ICD: the intrathoracic six-channel farfield ECG

Present-day ICD systems offer the possibility to reconstruct an intrathoracic 6-lead ECG (IT-ECG), using the defibrillator coils in the right ventricle and superior vena cava and the left-laterally positioned ICD as electrodes according to Einthoven and Goldberger. The aim of this study was to assess the feasibility of (1). automated P wave recognition in the IT-ECG without an additional atrial electrode as the basis of AV synchronous ventricular pacing (VDD) and for improved differentiation between supraventricular tachyarrhythmias and, (2). the automated detection of pacing evoked atrial potentials (EAP) in dual chamber ICDs as the basis for atrial "autocapture"pacing systems. In 27 patients during ICD implanation intraoperatively, the IT-ECG was digitally recorded. A recently established algorithm for automatic P wave and EAP detection correctly identified 1663/1672 (99.5%) P waves (oversensing rate 0.6%) and 543/554 (98.0%) EAP (no oversensing). During subthreshold atrial stimulation, 405/412 (98.3%) P waves were correctly identified (oversensing due to pacemaker spikes, n = 421, without subsequent EAP, 1.9%,n = 8). During stimulated ventricular tachycardia in 26/27 patients retrograde P wave or AV dissociation were identified. The 6-lead IT-ECG, easily implementable in ICD systems, is a diagnostic tool providing reliable information about atrial activation, serving as a basis for VDD pacing in single chamber ICD systems, allowing reliable EAP recognition that enables atrial "autocapture"pacing in dual chamber ICDs, and improves the differentiation between supraventricular and ventricular tachycardia.

Beat-to-beat assessment of QT/RR interval ratio in severe heart failure and overt myocardial ischemia: a measure of electrical integrity in diseased hearts

The study was designed to assess the beat-to-beat variation of ventricular repolarization in patients with myocardial ischemia, hear failure, and in normal subjects. Autonomic tone may alter the dynamic QT/RR interval relation and thus may be involved in ventricular arrhythmia development, especially in the diseased heart. The study included 145 patients (age 16-86 years) with CHF (LVEF < or = 0.30) or unstable angina pectoris (LVEF > 0.60). The control group consisted of healthy volunteers giving physiological baseline measures for the evaluated parameters: cycle length, QT interval, and QT/RR interval ratio during three time periods. In patients with myocardial ischemia (LVEF > 0.60) and healthy subjects the QT/RR interval ratio did not reveal significant differences between both groups (QT/RR(CAD) = 0.36 +/- 0.77 vs QT/RR(controls) = 0.28 +/- 0.83; NS). In sharp contrast, in patients with severe heart failure, RR dependent instantaneous variation of the QT interval was almost missing and regression line analysis disclosed a QT/RR interval slope substantially enhanced by 196% (compared to normal subjects) and 131% (compared to CAD patients; P < 0.05) with a complete loss of circadian modulation (QT/RR(CHF) = 0.83 +/- 0.71 vs QT/RR(CAD) = 0.36 +/- 0.77 vs QT/RR(controls) = 0.28 +/- 0.83; P < 0.05). Beat-to-beat QT interval assessment provides a dynamic parameter of physiological and altered repolarization in defined study groups. Compared to other groups (preserved LVEF), patients with left ventricular impairment exhibited a significantly increased sensitivity of repolarization to cycle length (enhanced QT/RR interval ratio) and a blunted circadian modulation of the QT interval. This is consistent with concept that increased repolarization disparity may be deleterious being a potential pathophysiological basis for enhanced arrhythmic risk.

[Bronchoscopy and rhythmic disorders. Premedication with atropine-sulfate, as a rule?]

Ikeda has introduced flexible bronchoscopy in the seventies of the last century. Since then the over one hundred year old procedure of direct airways inspection has widely spread and enhanced the diagnostic and therapeutic means. Thus the flexible bronchoscopy has become an important part of modern medicine. The close combination of atropine as premedication with bronchoscopy is justified with the terms "cardioprotection" and reduction of mucus secretion. As there is to this date no controlled study to prove this assumption, with the start of bronchoscopy we controlled every patient with a holter-ecg for 24-hours and estimated semiquantitatively the mucus secretion during procedure by a four point scale. Consecutively 55 patients could be randomised, 25 (7 females, 18 males) in the group with and 30 (7 females, 18 males) without atropine. In the records there were no detectable significant differences between the groups with atropine (A) and without atropine (P), as well as for registered bradycardias (A: 0 vs. P: 0, minimum of heart beats A: 63.8 vs. P: 74.1 min -1) as well as for alterations of heart rhythms, e. g. SVES (A: 7.3 % vs. P: 5.5 %), VES (A: 9.0 % vs. P: 9.0 %) or a combination of SVES with VES (A: 12.7 % vs. P: 10.9 %). The same results could be seen for each single of the first twenty minutes, additionally the first and the second recorded hour and the whole registered 24 hours. Moreover the times needed to complete the bronchoscopy showed no significant difference (mean of t A: 16.8 vs. P: 15.6 min, t-minimum 10 vs. 10 min, t-maximum A: 30 vs. P: 35 min). The same absence of differences was seen in estimated endobronchial mucus secretion (mean A: 1.88 vs. P: 2.0). According to these results of our studied group, there are no reasons, why a premedication with atropine in flexible bronchoscopy in local anaesthesia should be used. Even without the administration of atropine, flexible bronchoscopy could be performed as a safe and sophisticated method in direction of not inducing relevant arrhythmia, with low impact on patients.

[New aspects of ICD therapy: from rhythm therapy to complex cardiac monitoring. Development of an implantable, ICD-assisted, intrathoracic 6-channel ECG for continuous monitoring of high infarct risk patients]

Implantable defibrillator systems (ICD) are therapy of choice for the treatment of life-threatening ventricular arrhythmias and in prevention of sudden cardiac death. In more than 80% of patients who receive an ICD, the underlying cardiac disease is a coronary heart disease. Since arrhythmogenic sudden cardiac death can be reliably prevented in these patients by the use of ICD technology, the cardiac prognosis for these patients is determined by the occurrence of myocardial ischemia and myocardial infarction, as well as from the heart failure which develops in consequence. An intrathoracic 6-channel ECG comparable to the standard surface ECG can be reconstructed by further technical development of the electrode configurations currently present in ICD systems. The importance of this development in early diagnosis of myocardial ischemias and myocardial infarction can hardly be adequately estimated at the moment. The chronic consequences of myocardial infarction can be completely prevented or at least greatly reduced by means of such diagnostics and inclusion of immediate initiation of effective, appropriate early therapeutic measures before more serious symptoms even occur. In the development and pilot studies thus far, it has been found that the intrathoracic 6-channel ECG which can be generated in the ICD is capable of reliably recognizing acute myocardial ischemia, irrespective of localization or extent earlier and better than the standard surface ECG. Continuous preventive ischemia monitoring using the implanted ICD thus appears possible in patients at risk of infarction.

Transmyocardial laser revascularization and left ventricular reduction surgery affect ventricular arrhythmias and heart rate variability

BACKGROUND

Transmyocardial laser revascularization (TMLR) and left ventricular reduction by endoventricular patch plasty (LVR) are 2 new surgical procedures performed in patients with endstage coronary artery disease and left ventricular dilation/aneurysms, respectively. As these are performed in patients at high risk for sudden cardiac death and may interact with arrhythmogenesis, we assessed the influence of these procedures on incidence and severity of ventricular tachyarrhythmias and time-domain heart rate variability.

METHODS

Preoperative and one week postoperative 24-hour Holter recordings were performed in 37 patients undergoing TMLR (n = 23, CO2-laser technique) or LVR (n = 14).

RESULTS

TMLR patients received a mean of 27.2 +/- 9.2 laser channels. Postoperatively, the proportion of patients who underwent TMLR with spontaneous ventricular tachycardia (> or =4 repetitive ventricular beats) increased (0% vs 26%, P <.05), including one patient who died from documented ventricular fibrillation during monitoring. There was no correlation to the number and/or location of laser-induced channels or to perioperative CK levels. HRV parameters were not altered by TMLR. By contrast, LVR did not significantly influence ventricular tachyarrhythmia episodes but markedly depressed all major HRV parameters (SDNN 116.4 vs 61.8, RMSSD 35.2 vs 19.9, pNN50 14.5 vs 4.9, all P <.05).

CONCLUSIONS

Early after TMLR, there is evidence of an increased incidence of spontaneous ventricular tachycardia enhancing the risk for sudden cardiac death, while HRV remains unaffected. By contrast, LVR resulted in a marked reduction in HRV still present one week postoperatively, while no effect was observed on incidence and/or severity of spontaneous ventricular tachyarrhythmias.

Extragonadal retroperitoneal germ cell tumor: evidence of origin in the testis

BACKGROUND

The origin of extragonadal retroperitoneal germ cell tumors remains controversial. Whether they develop primarily in the retroperitoneum or whether they are metastases of a primary testicular tumor has long been debated.

PATIENTS AND METHODS

We retrospectively analyzed 26 patients treated as having primary extragonadal retroperitoneal germ cell tumors based upon the findings of testicular palpation by the referring physician. Testicular evaluation was then extended with ultrasonographical and histological examinations.

RESULTS

Biopsy of the extragonadal tumor was performed in 25 patients, confirming diagnosis of extragonadal retroperitoneal germ cell tumor. Prior to treatment patients were clinically evaluated by several physicians and the testes were not considered suspicious for testicular cancer. At urological workup, testes were found to be atrophic and/or indurated in 14 (54%) patients, enlarged in one (4%) and unremarkable in 11 (42%). Ultrasound examination of the testes in 20 patients showed pathological findings in all of them. Histology of the testis was available in 25 of 26 patients and revealed active tumor in three, intratubular germ cell neoplasia in four, scar tissue in 12, sclerosis in three, sclerosis and fibrosis in one, and fibrosis alone in two.

CONCLUSIONS

So-called primary extragonadal germ cell tumors in the retroperitoneum are very likely a rare or non-existing entity and should be considered as metastases of a viable or burned-out testicular cancer until proven otherwise. All of our patients with histologically examined testes had pathological finding, 76% of which were either viable tumor or scars.

Impact of electrocardiogram recording format on QT interval measurement and QT dispersion assessment

The aim of this study was to determine the effect of recording conditions on the operator dependent measures of QT dispersion in patients with known and/or suspected repolarization abnormalities. Among several methods for risk stratification, QT dispersion has been suggested as a simple estimate of repolarization abnormalities. In a cohort of high and low risk patients, different components of the repolarization process were assessed in the 12-lead ECG using three different paper speeds and amplifier gains. To assess measurement error and reproducibility, a straight line was repeatedly measured. The operator error was 0.675 +/- 0.02 mm and the repeatability of the measurement error was 31 +/- 6%. The QT interval was most frequently measurable in V2-V5. Depending on the lead selected for analysis, the incidence of visible U waves was greatest in the precordial leads with high amplifier gain and low paper speed, strongly affecting QT interval measurement. The timing of the onset of the QRS complex (QRS onset dispersion) or offset of the T wave was strongly dependent on the paper speed. Paper speed, but not amplifier gain, had a significant shortening effect on the measurement of the maximum QT interval. As QT interval measurement in each ECG lead incorporates QRS onset and T wave offset (depending on the number of visible U waves), the dispersion of each of these parameters significantly affected QT dispersion. Thus, QT dispersion appears to reflect merely the presence of more complex repolarization patterns in patients at risk of arrhythmias.

Beta-blocking agents vs. antiarrhythmic interventions in heart failure complicated by arrhythmias

Approximately 40-50% of the patients with end-stage cardiac failure (either ischemic or nonischemic) die suddenly and unexpectedly, most probably from ventricular fibrillation. It is unclear whether the complex ventricular arrhythmias observed in large numbers of these patients were related to the mode of death. Theoretically, it seems quite reasonable to attempt to suppress the development of life-threatening ventricular arrhythmias (e.g., sustained ventricular tachycardia or ventricular fibrillation) in those patients. If antiarrhythmic drug therapy is ineffective, alternative antiarrhythmic interventions (antiarrhythmic surgery or implantation of an automatic implantable cardioverter defibrillator) should be considered. In patients with so-called potentially malignant ventricular arrhythmias (e.g., nonsustained ventricular tachycardia), antiarrhythmic drug therapy remains controversial as presently there is no definitive proof that this therapy prolongs life or reduces the incidence of sudden cardiac death. In patients with end-stage cardiac failure, beta-blockade can result in a decrease in resting tachycardia, improvement in clinical heart failure symptoms, and increase in work load capacity. It remains controversial whether treatment with these agents can also improve prognosis and prevent sudden cardiac death. Therefore, at this time, only patients in the earlier stages of this clinical syndrome and with clinical signs of markedly increased sympathetic tone can be treated with low doses of beta-blockers.

[Acute myocardial ischemia and ventricular arrhythmias in the pathogenesis of sudden cardiac death in coronary disease]

There is increasing evidence for a fatal interaction of myocardial ischemia, ventricular arrhythmias and sudden cardiac death in some patients with coronary artery disease. Evidence comes from autopsy studies, from the evaluation of patients who survived an episode of sudden cardiac death, from follow-up data of these patients either treated or not by revascularization therapy and/or an implantable cardioverter-defibrillator and indicate that reducing the individual ischemic burden will be beneficial to reduce the incidence of sudden cardiac death. Studies in patients with stable and especially with unstable angina using Holter monitoring could demonstrate that there is a close and causal relationship between myocardial ischemia inducing or aggravating life-threatening ventricular arrhythmias and sudden cardiac death particularly in patients with unstable and postinfarction status. This review summarizes some of our clinical knowledge on this topic and indicates that preventive strategies for myocardial ischemia are the antiarrhythmic treatment of choice in patients with severe coronary artery disease and patients with evidence or at risk for ischemic proarrhythmia.

Usefulness of carvedilol in unstable angina pectoris

The safety and efficacy of adding oral carvedilol (25 mg twice daily) to standardized treatment of unstable angina was assessed in a multicenter, randomized, double-blind, placebo- controlled trial on 116 patients with acute unstable angina. Patients were monitored in an intensive care unit and underwent 48-hour Holter monitoring to assess transient ischemia. Carvedilol as adjunctive therapy resulted in a significant reduction of median heart rate (65 vs 75 beats/min, p <0.05), mean systolic blood pressure (133 vs 130 mm Hg, p <0.05), and mean rate-pressure product (8,337 vs 10,042, p <0.05). Carvedilol reduced the ischemic burden during 48 hours of treatment by 75% (49 vs 204 minutes), including a 36% reduction of patients with ischemic episodes (p <0.05), a 66% reduction of the mean number of ischemic episodes (8 vs 24, p <0.05), and a 76% reduction in the mean duration of ischemic episodes (50 vs 205 minutes, p <0.05). Side effects occurred in 8 of 59 patients (13.6%) in the carvedilol group and in 5 of 54 patients (8.8%) given placebo. Although not significant, the early onset of maximal blood pressure reduction and the delayed effect on heart rate were closely correlated to drug-induced hypotension and bradycardia in the carvedilol group. Thus, carvedilol as an adjunctive to standardized treatment effectively reduces heart rate and blood pressure, and thus the ischemic burden in patients with unstable angina pectoris, but requires close monitoring of patients at risk for bradycardia or hypotension.

[Antiarrhythmic therapy in patients with heart failure]

In patients with severe chronic heart failure, many deaths are sudden due to life-threatening ventricular arrhythmias. Supraventricular arrhythmias such as paroxysmal or chronic atrial fibrillation may also cause serious complications in those patients due to acute loss of atrial contraction, pump failure during rapid ventricular response and embolic events. Two therapeutic strategies are currently available for therapy and prevention of malignant ventricular arrhythmias and subsequent sudden arrhythmic death: antiarrhythmic drug therapy and implantable defibrillators. However, selection of the most beneficial strategy for the individual patient to reduce the risk of sudden death remains a major challenge in cardiology. Betablockers exert a favorable antiarrhythmic action without increasing proarrhythmia, thus betablockers may serve as a basic medication in patients at risk for sudden death. However, the general use of antiarrhythmic drug therapy for symptomatic ventricular arrhythmias is not recommended, as these drugs have been shown to increase mortality in patients with severe congestive heart failure due to proarrhythmic or negative inotropic effects (e.g. class Ia antiarrhythmics). Even class III antiarrhythmic drugs such as amiodarone, which has been studied sufficiently in patients with left ventricular dysfunction, is not effective enough for significant reduction of cardiac mortality in patients with symptomatic ventricular arrhythmias and depressed ventricular function (e.g. EMIAT, CAMIAT). But as a positive result of available studies, amiodarone does not increase mortality in those patients. Dofetilide has also not been shown to prolong life significantly by suppressing malignant ventricular arrhythmias (DIAMOND-Study). In patients with symptomatic ventricular arrhythmias or aborted sudden death, ICD therapy has been proven to be superior to antiarrhythmic drug therapy in cardiac mortality reduction as a secondary prevention strategy (e.g. AVID, CASH, CIDS). For primary prevention of sudden arrhythmic death in high risk patients, 2 studies (MADIT, MUSST) have already demonstrated favorable results, decreasing mortality by ICD therapy in selected patient populations with partly-reduced ventricular function and unsustained but inducible ventricular tachycardias. This topic is, however, undergoing further evaluation by ongoing trials (e.g. MADIT II, SCD-HeFT). From available data, antiarrhythmic drug therapy in high risk patients is not justified on a routine basis, whereas ICD therapy as a secondary and perhaps primary prevention strategy will significantly reduce cardiac mortality in patients with severe heart failure. Sotalol, a class III antiarrhythmic agent, has recently been shown to reduce ICD-shock delivery which indicates that concomitant drug therapy in patients with an ICD device already implanted may be beneficial in terms of reducing ICD discharges due to ventricular and supraventricular tachycardias. In patients with paroxysmal atrial fibrillation and congestive heart failure, restitution of sinus rhythm is the primary therapeutic goal which can be safely achieved by amiodarone and dofetilide (DIAMOND). In the latter, continuous monitoring of the patient is mandatory because of increased risk of torsade de pointes arrhythmias during the first days of drug administration. In patients with chronic atrial fibrillation rate control and anticoagulation with warfarin is the primary therapeutic option, which can be achieved with either drug treatment (Digoxin, betablockers, amiodarone) or by His bundle ablation with subsequent pacemaker insertion.

3D assessment of myocardial perfusion parameter combined with 3D reconstructed coronary artery tree from digital coronary angiograms

In patients with coronary artery disease coronary angiography plays an important role in the clinical decision-making process. However, it has been recognized that no simple relation exists between the visually or quantitatively evaluated severity of coronary artery stenoses and its effects on regional myocardial perfusion. This paper describes for the first time the development and application of a 3D technique that visualizes and quantifies regional myocardial perfusion parameters from biplane coronary angiograms by using the impulse response analysis technique. The 3D reconstructed coronary tree is automatically superimposed on the 3D perfusion image to generate and visualize an 'integrated' 3D image. The preliminary results in patients with critical coronary artery stenoses indicate that our combined 3D fusion image provides flow information from the major coronary arteries. This 3D fusion image may provide useful information in the management of patients with coronary artery disease.

Fusion imaging: combined visualization of 3D reconstructed coronary artery tree and 3D myocardial scintigraphic image in coronary artery disease

BACKGROUND

In patients with coronary artery disease, coronary angiography is performed for assessment of epicardial coronary artery stenoses. In addition, myocardial scintigraphy is commonly used to evaluate regional myocardial perfusion. These two-dimensional (2D) imaging modalities are typically reviewed through a subjective, visual observation by a physician. Even though on the analysis of 2D display scintigraphic myocardial perfusion segments are arbitrarily assigned to three major coronary artery systems, the standard myocardial distribution territories of the coronary tree correspond only in 50-60% of patients. On the other hand, the mental integration of both 2D images of coronary angiography and myocardial scintigraphy does not allow an accurate assignment of particular myocardial perfusion regions to the corresponding vessels. To achieve an objective assignment of each vessel segment of the coronary artery tree to the corresponding myocardial regions, we have developed a 3D 'fusion image' technique and applied it to patients with coronary artery disease. The morphological data (coronary angiography) and perfusion data (myocardial scintigraphy) are displayed in a 3D format, and these two 3D data sets are merged into one 3D image.

RESULTS

Seventy-eight patients with coronary artery disease were studied with this new 3D fusion technique. Of 162 significant coronary lesions, 120 (74%) showed good coincidence with regional myocardial perfusion abnormality on 3D fusion image. No regional myocardial perfusion abnormality was found in 44 (26%) lesions. Furthermore, the 3D fusion image revealed 24 ischemic myocardial regions that could not be related to angiographically significant coronary artery lesions.

CONCLUSION

The results of this study demonstrate that our newly developed 3D fusion technique is useful for an accurate assignment of coronary vessel segments to the corresponding myocardial perfusion regions, and suggest that it may be helpful to improve the interpretative and decision-making process in the treatment of patients with coronary artery disease.

[Arterial occlusion of the eye in infectious endocarditis]

BACKGROUND

Infectious endocarditis can lead to embolic arterial retinal occlusions. Which therapy is indicated?

RESULTS

A 33-year-old man suddenly became blind in his left eye as the result of a central retinal artery occlusion (CRAO). This occurred during high-dosage treatment for infectious endocarditis that had been diagnosed 3 weeks earlier. The echocardiogram showed distinct vegetation and an abscess on the aortic valve. The CRAO together with the ultrasound findings was considered an absolute indication for surgery of the aortic valve. During this emergency operation, a 2 cm deep abscess cavity was found between the mitral and aortic valves. After removal of the abscess, together with the infected valve, a prosthetic valve was inserted. Following the operation, the patient made an uneventful recovery. The antibiotic treatment was continued for several months. The left eye remained sightless. No recurrence of infectious endocarditis occurred during the follow-up of 2 1/4 years. A branch retinal arterial occlusion occurred in the right eye of a 35-year-old man who had suffered from chronic infectious endocarditis for several months. Insufficiency of more than one valve had been diagnosed on several occasions. The patient, a drug-addict, had refused surgical treatment on each occasion. After 3 months, the right eye became completely blind owing to CRAO. Following high-dosage treatment with antibiotics, the infectious endocarditis was healed. The right eye remained blind. One year later the patient died.

CONCLUSION

Retinal arterial occlusion of embolic origin in a patient with infectious endocarditis is an indication for immediate medical and/or surgical treatment. This is of particular importance if there is ultrasound evidence of an abscess in the valve area.

[Risk assessment in coronary heart disease: ventricular arrhythmias, myocardial ischemia and sudden cardiac death]

There is increasing evidence for a fatal interaction of myocardial ischemia, ventricular arrhythmias, and sudden cardiac death in some patients with coronary artery disease. Evidence comes from autoptic studies, from the evaluation of patients who survived an episode of sudden cardiac death, from follow-up data of these patients either treated or not by revascularization therapy and/or an implantable cardioverter-defibrillator and indicate that reducing the individual ischemic burden will be beneficial to reduce the incidence of sudden cardiac death. Studies in patients with stable and especially with unstable angina using Holter monitoring could demonstrate that there is a close and causal relationship between myocardial ischemia inducing or aggravating life-threatening ventricular arrhythmias and sudden cardiac death particularly in patients with unstable and postinfarction status. This review summarizes some of our clinical knowledge on this topic and indicates that preventive strategies for myocardial ischemia are the antiarrhythmic treatment of choice in patients with severe coronary artery disease and evidence or at risk for ischemic proarrhythmia.

[Magnesium deficiency and magnesium substitution. Effect on ventricular cardiac arrhythmias of various etiology]

During recent years there has been an increasing but still controversial discussion on the antiarrhythmic effects and overall benefit of magnesium when directed to patients with various types of ventricular tachyarrhythmias. While magnesium is considered to be a simple, safe and cost-effective approach and many casuistic and empiric reports have indicated antiarrhythmic properties of magnesium in patients with suspected or manifest ventricular arrhythmias, controlled studies proving the antiarrhythmic and overall benefit and justifying a broader use of magnesium in treating various types of ventricular arrhythmias are missing or rare. At present, antiarrhythmic properties and clinical benefit of magnesium application has only been established in patients with torsade de pointes and digitalis-induced ventricular tachyarrhythmias. In perioperative patients at risk for ventricular tachyarrhythmias and in patients suffering from manifest heart failure, data may also indicate some antiarrhythmic properties of magnesium, however, in this case with a wide consensus that the prevention of magnesium deficit is more effective and preferred in most patients over the therapeutic application of magnesium. Another group of patients who may profit from such a therapeutic approach are patients with frequent ventricular arrhythmias and stable underlying heart disease, in whom a recently published double-blind, randomized study documented an antiarrhythmic effect of a 3 week treatment with potassium and magnesium. For all other types of ventricular tachyarrhythmias, the therapeutic use of magnesium can be considered as not harmful, but also as not proven to be effective.