P-009 OPEN VS LAPAROSCOPIC VS ROBOT-ASSISTED INGUINAL HERNIA REPAIR: A CASE SERIES

Aim

Minimally invasive inguinal hernia repair is thought to be associated with fewer complications. To address this hypothesis, we compared short- and long-term complications in patients undergoing elective open (Lichtenstein), laparoscopic (TAPP) and robot-assisted inguinal hernia repair (rTAPP).

Material & Methods

Patients undergoing either, Lichtenstein, TAPP or rTAPP at our institution between January 1st 2017 and December 30th 2019 were retrospectively identified. Short (haematoma, seroma, surgical-site infections) and long-term complications (chronic pain, recurrence) were recorded and compared between groups.

Results

636 patients were included in the study. 370 were treated with Lichtenstein, 125 TAPP and 141 with rTAPP. There was a significant overweight of men in all groups (p < 0,001). Among the rTAPP group, the overall rate of complications was reduced (open: 10.0%; laparoscopic: 8.8%; robot-assisted 5.7%) while the presence of chronic pain was slightly more prevalent (Lichtenstein: 1.6%; TAPP: 1.6%; rTAPP: 2.1%). The rate of recurrence was lower following rTAPP (Lichtenstein: 3.8%; TAPP: 2.4%; rTAPP: 1.4%). Same day discharged was more likely following the open technique (open: 88.9%; laparoscopic: 78.4%; robot-assisted 78.7%). Nevertheless, these results were not statistically significant (p>0.05).

Conclusions

The present case series demonstrates a comparable rate of short and long-term complications following open and minimally invasive inguinal hernia repair. The trend towards a lower overall complications rate and recurrence rate, though not statistically significant, implies that minimally invasive surgery might be associated with a lower complication and recurrence rate. However, a larger prospective study design with a longer follow-up is needed to test this hypothesis.

Validation of the Danish versions of the Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaires (BRAFs)

Objective: This study aimed to validate the Danish versions of the Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaire (BRAF-MDQ) and BRAF Numerical Rating Scale version 2 (NRSv2).Method: We tested face and content validity, internal consistency, criterion validity, construct validity, and reproducibility for the BRAF-MDQ, and face and criterion validity and reproducibility for the BRAF-NRS.Results: In all, 224/236 patients (95%) completed the questionnaires [70% female, mean ± sd age 59 ± 13.04 years, disease duration 11.2 ± 9.49 years, Health Assessment Questionnaire (HAQ) 0.724 ± 0.70, and 28-joint Disease Activity Score-C-reactive protein 2.55 ± 1.24]. The unidimensionality for the physical and cognitive fatigue subscales was confirmed, whereas the living with fatigue and emotional fatigue subscales were not unidimensional. Cronbach's α was 0.94 for the BRAF-MDQ total and 0.78-0.92 for the four subscales. The correlations between BRAF-MDQ and various measures were: 36-item Short Form Health Survey (SF-36) vitality subscale, 0.75; Hospital Anxiety and Depression Scale (HADS) anxiety subscale, 0.65; HADS depression subscale, 0.62; visual analogue scale (VAS) pain, 0.62; VAS global, 0.73; and HAQ, 0.62. The intraclass correlation coefficient for agreement was 0.995. A Bland-Altman plot showed a mean ± sd difference of -1.9 ± 3.62 for BRAF-MDQ. Correlation coefficients between the BRAF-NRSv2 subscales and other subscales were: BRAF-MDQ subscales, 0.57-0.93; SF-36 vitality subscale, 0.54-0.68; and VAS fatigue, 0.66-0.82.Conclusions: The Danish BRAFs are considered valid and reliable for use among Danish patients with rheumatoid arthritis, despite the subscales living with fatigue and emotional fatigue not being unidimensional, as they are in the original version.

Tumor microenvironment conditions alter Akt and Na+/H+ exchanger NHE1 expression in endothelial cells more than hypoxia alone: implications for endothelial cell function in cancer

BACKGROUND

Chronic angiogenesis is a hallmark of most tumors and takes place in a hostile tumor microenvironment (TME) characterized by hypoxia, low nutrient and glucose levels, elevated lactate and low pH. Despite this, most studies addressing angiogenic signaling use hypoxia as a proxy for tumor conditions. Here, we compared the effects of hypoxia and TME conditions on regulation of the Na⁺/H⁺ exchanger NHE1, Ser/Thr kinases Akt1-3, and downstream effectors in endothelial cells.

METHODS

Human umbilical vein endothelial cells (HUVEC) and Ea.hy926 endothelial cells were exposed to simulated TME (1% hypoxia, low serum, glucose, pH, high lactate) or 1% hypoxia for 24 or 48 h, with or without NHE1 inhibition or siRNA-mediated knockdown. mRNA and protein levels of NHE1, Akt1-3, and downstream effectors were assessed by qPCR and Western blotting, vascular endothelial growth factor (VEGF) release by ELISA, and motility by scratch assay.

RESULTS

Within 24 h, HIF-1α level and VEGF mRNA level were increased robustly by TME and modestly by hypoxia alone. The NHE1 mRNA level was decreased by both hypoxia and TME, and NHE1 protein was reduced by TME in Ea.hy926 cells. Akt1-3 mRNA was detected in HUVEC and Ea.hy926 cells, Akt1 most abundantly. Akt1 protein expression was reduced by TME yet unaffected by hypoxia, while Akt phosphorylation was increased by TME. The Akt loss was partly reversed by MCF-7 human breast cancer cell conditioned medium, suggesting that in vivo, the cancer cell secretome may compensate for adverse effects of TME on endothelial cells. TME, yet not hypoxia, reduced p70S6 kinase activity and ribosomal protein S6 phosphorylation and increased eIF2α phosphorylation, consistent with inhibition of protein translation. Finally, TME reduced Retinoblastoma protein phosphorylation and induced poly-ADP-ribose polymerase (PARP) cleavage consistent with inhibition of proliferation and induction of apoptosis. NHE1 knockdown, mimicking the effect of TME on NHE1 expression, reduced Ea.hy926 migration. TME effects on HIF-1α, VEGF, Akt, translation, proliferation or apoptosis markers were unaffected by NHE1 knockdown/inhibition.

CONCLUSIONS

NHE1 and Akt are downregulated by TME conditions, more potently than by hypoxia alone. This inhibits endothelial cell migration and growth in a manner likely modulated by the cancer cell secretome.

Prophylactic cavotricuspid isthmus block during atrial fibrillation ablation in patients without atrial flutter: a randomised controlled trial

OBJECTIVES

This randomised trial evaluated if patients with atrial fibrillation (AF) and no history of atrial flutter (AFL) had any benefit of prophylactic cavotricuspid isthmus block (CTIB) in addition to circumferential pulmonary vein ablation (CPVA).

METHODS

149 patients with AF (54% paroxysmal) were randomised to CPVA and CTIB (group CTIB+, n = 73) or CPVA alone (group CTIB-, n = 76). Patients were followed for 12 months with repetitive 7-day Holter monitoring after 3, 6 and 12 months.

RESULTS

Six patients (4%) had cardiac tamponade, and one patient had a stroke. No difference was found in the cumulative AFL-free rate between the two treatment groups (CTIB+: 88% vs CTIB-: 84%, hazard ratio (HR) 0.80, 95% CI (0.34 to 1.90), p = 0.61). There was no difference in the cumulative AF-free rate between the groups (CTIB+: 34% vs CTIB-: 32%, HR 0.93, 95% CI (0.63 to 1.38), p = 0.71). Overall, 33% of the patients were free of AF after a single procedure. Including reprocedures, a complete or partial beneficial effect was noted in 62% of the patients at 12 months. At 12-month follow-up, 24 (50%) patients with documented AF or AFL in the Holter recordings were asymptomatic.

CONCLUSIONS

It was not possible to demonstrate any beneficial effect of CTIB in addition to CPVA with regard to AFL or AF recurrences during follow-up. Repetitive long-term Holter monitoring demonstrated a 33% rate of freedom from AF during a 1-year follow-up. Including additional CPVA procedures, a clinical effect was noted in 62% of the patients at 12 months. Patients with AF or AFL recurrences were often asymptomatic.

Improving the reproducibility of QT dispersion measures

BACKGROUND

The low reproducibility of the QT dispersion (QTD) method is a major reason why it is not used in clinics. The purpose of this study was to develop QT dispersion parameters with better reproducibility and identification of patients with a high risk of ventricular arrhythmia or death.

METHODS AND RESULTS

Three institutions using different methods for measuring QT intervals provided QT databases, which included more than 3500 twelve-lead surface ECGs. The data represented low and high risk subjects from the following groups: the normal population EpiSet (survivors vs dead from cardiovascular causes), acute myocardial infarction patients AmiSet (survivors vs dead) and remote myocardial infarction patients ArrSet (with vs without a history of ventricular arrhythmia). The EpiSet, AmiSet, and the ArrSet contributed with N = 122, 0, and 110 ECGs for reproducibility analysis, and 3244, 446, and 100 ECGs for the analysis of prognostic accuracy. The prognostic accuracy was measured as the area under the Receiver Operator Curve. The QT intervals were divided into six QT pairs; the longest pair consisted of the longest and the shortest QT intervals etc. The QT dispersion trend (QTDT) was defined as the slope of the linear regression of the N longest QT pairs after estimation of missing QT intervals by interpolation of measured QT intervals. The QTMAD and the QTSTD methods were defined as twice the mean absolute deviation and the standard deviation of the N longest QT pairs. The reproducibility was improved by 27% and 19% in the EpiSet and the ArrSet relative to the reproducibility of QTD. The accuracy improved for the EpiSet and the ArrSet and was maintained for the AmiSet.

CONCLUSIONS

By using the three longest and the three shortest QT intervals in QTDT, QTMAD, or QTSTD, the reproducibility improved significantly while maintaining or improving the prognostic accuracy compared to QTD.

Reproducibility of QT parameters derived from 24-hour ambulatory ECG recordings in healthy subjects

AIM

To estimate the reproducibility of QT parameters derived from 24-hour ambulatory ECG recordings.

METHOD

Ten healthy volunteers aged 25 to 41 years participated. In two 24-hour ambulatory ECG recordings obtained 1 day apart, the QT interval was measured manually at stable heart rates in approximately 16 periods during daytime and 6 periods during nighttime. The association between the QT and RR interval was described by linear regression for day and nighttime separately and the following QT parameters were calculated: the QT interval at heart rate 60 beats/min during daytime (QT(60)day), slope(day), slope(night), and the difference in QT(60) between day and nighttime (DeltaQT(60)). The QT parameters were assessed four times for each participant to discriminate method inaccuracy from day to day variation. The reproducibility was estimated as the coefficient of repeatability, the relative error, and the ratio between within-subject variability and between-subject variability.

RESULTS

The coefficient of repeatability, the relative error and the ratio, respectively, were 19 ms, 1.8% and 0.5 for QT(60)day, 0.076, 21% and 0.68 for slope(day), 0.116, 43% and 1.37 for slope(night), and 37 ms, 325% and 1.19 for DeltaQT(60) when estimating the overall day to day reproducibility. Inaccuracy of QT measurement accounted for approximately 40% of this variation, whereas the error caused by selecting segments was small.

CONCLUSION

QT(60)day has a high reproducibility and may with advantage replace the conventional QT interval measured on a resting ECG. To assess QT dynamics, the slope of the regression line during daytime is suitable and the short term reproducibility acceptable for clinical trials. Regarding slope(night) and DeltaQT(60), the variation is high and the parameters should be used with caution.

Bias of QT dispersion

BACKGROUND

Prolonged QT dispersion (QTD) is associated with an increased risk of arrhythmic death but its accuracy varies substantially between otherwise similar studies. This study describes a new type of bias that can explain some of these differences.

MATERIAL

One dataset (DiaSet) consisted of 356 subjects: 169 with diabetes, 187 nondiabetic control persons. Another dataset (ArrSet) consisted of 110 subjects with remote myocardial infarction: 55 with no history of arrhythmia and 55 with a recent history of ventricular tachycardia or fibrillation.

METHODS

12-lead surface ECGs were recorded with an amplification of 10 mm/mV at a paper speed of 50 mm/s. The QT interval was measured manually by the tangent-method. The bias depends on the magnitude of the measurement errors and the measurable part of the bias increases with the number of the repeated measurements of QT.

RESULTS

The measurable bias was significant for both datasets and decreased for increasing QTD in the DiaSet (P < 0.001) and in the ArrSet (P = 0.11). The bias was 2.5 ms and 1.9 ms at QTD = 38 ms and 68 ms, respectively, in the ArrSet, and 7.5 ms and 2.8 ms at QTD = 19 ms and 55 ms, respectively, in the DiaSet.

CONCLUSIONS

This study shows that random measurement errors of QT introduces a type of bias in QTD that decreases as the dispersion increases, thus reducing the separation between patients with low versus high dispersion. The bias can also explain some of the differences in the mean QTD between studies of healthy populations. Averaging QT over three successive beats reduces the bias efficiently.

Incidence of atrial fibrillation and thromboembolism in a randomised trial of atrial versus dual chamber pacing in 177 patients with sick sinus syndrome

OBJECTIVE

To analyse the occurrence of atrial fibrillation (AF) and thromboembolism in a randomised comparison of rate adaptive single chamber atrial pacing (AAIR) and dual chamber pacing (DDDR) in patients with sick sinus syndrome and normal atrioventricular (AV) conduction, in which left atrial dilatation and decreased left ventricular fractional shortening had been observed in the DDDR group.

METHODS

177 consecutive patients with sick sinus syndrome (mean (SD) age 74 (9) years, 104 women) were randomly assigned to treatment with one of three pacemakers: AAIR (n = 54), DDDR with a short rate adaptive AV delay (n = 60) (DDDR-s); or DDDR with a fixed long AV delay (n = 63) (DDDR-l). Analysis was intention to treat.

RESULTS

Mean follow up was 2.9 (1.1) years. AF at one or more ambulatory visits was significantly less common in the AAIR group (4 (7.4%) v 14 (23.3%) in the DDDR-s group v 11 (17.5%) in the DDDR-l group; p = 0.03, log rank test). The risk of developing AF in the AAIR group compared with the DDDR-s group was significantly decreased after adjustment for brady-tachy syndrome in a Cox regression analysis (relative risk 0.27, 95% confidence interval (CI) 0.09 to 0.83, p = 0.02). The benefit of AAIR was highest among patients with brady-tachy syndrome. Brady-tachy syndrome and a thromboembolic event before pacemaker implantation were independent predictors of thromboembolism during follow up (relative risk 7.5, 95% CI 1.6 to 36.2, p = 0.01, and relative risk 4.7, 95% CI 1.2 to 17.9, p = 0.02, respectively).

CONCLUSIONS

During a mean follow up of 2.9 years AAIR was associated with significantly less AF. The beneficial effect of AAIR was still significant after adjustment for brady-tachy syndrome. Brady-tachy syndrome was associated with an increased risk of thromboembolism.

Impact of acute biventricular pacing on left ventricular performance and volumes in patients with severe heart failure. A tissue doppler and three-dimensional echocardiographic study

OBJECTIVES

We used tissue velocity imaging (TVI) and three-dimensional echocardiography to evaluate the effect of acute biventricular pacing on left ventricular (LV) performance and volumes in patients with severe heart failure and bundle branch block.

BACKGROUND

Biventricular pacing causes acute hemodynamic improvement in patients with severe heart failure, and QRS duration has been used as a predictor of improved resynchronization. Tissue velocity has the potential of demonstrating the degree of LV resynchronization and three-dimensional echocardiography enables accurate quantitation of LV volumes and function.

METHODS

TVI and three-dimensional echocardiography were performed during sinus rhythm and biventricular pacing in 25 consecutive patients with severe heart failure.

RESULTS

Biventricular pacing significantly improved the extent of contracting myocardium in synchrony by 15.4% and the duration of contraction synchrony by 17% (p < 0.05 for both). Furthermore, end-diastolic and end-systolic volumes decreased by 7 +/- 4.5% and 13 +/- 6% (p < 0.01) and ejection fraction increased by 22.8 +/- 9% (p < 0.01). Baseline duration of QRS and the preejection period as well as the extent of myocardium with asynchronous contraction measured by TVI predicted pacing efficacy. In multivariate analysis, only the extent of myocardium with asynchronous contraction at the LV base predicted biventricular pacing efficacy.

CONCLUSION

Biventricular pacing improves LV systolic performance and reduces LV volumes during short-term treatment. TVI provides important pathophysiological information on the degree of LV resynchronization and may contribute to improved patient selection.

Task Force on Sudden Cardiac Death, European Society of Cardiology

The European Society of Cardiology has convened a Task Force on Sudden Cardiac Death in order to provide a comprehensive, educational document on this important topic. The main document has been published in the European Heart Journal in August 2001. The Task Force has now summarized the most important clinical issues on sudden cardiac death and provided tables with recommendations for risk stratification and for prophylaxis of sudden cardiac death. The present recommendations are specifically intended to encourage the development and revision of national guidelines on prevention of sudden cardiac death. The common challenge for cardiologists, physicians of other medical specialties and health professionals throughout Europe is to realize the potential for sudden cardiac death prevention and to contribute to public health efforts to reduce its burden.

Three dimensional echocardiography documents haemodynamic improvement by biventricular pacing in patients with severe heart failure

OBJECTIVES

To quantify the short term haemodynamic effects of biventricular pacing in patients with heart failure and left bundle branch block by using three dimensional echocardiography.

DESIGN

Three dimensional echocardiography was performed in 15 consecutive heart failure patients (New York Heart Association functional class III or IV) with an implanted biventricular pacing system. Six minute walk tests were performed to investigate the effect of biventricular pacing on exercise capacity. Data were acquired at sinus rhythm and after short term (2-7 days) biventricular pacing.

RESULTS

Compared with baseline values, biventricular pacing significantly reduced left ventricular end diastolic volume (EDV) by mean (SD) 4.0 (5.1)% (p < 0.01) and end systolic volume (ESV) by 5.6 (6.4)% (p < 0.02). Mitral regurgitant fraction was significantly reduced by 11 (12.1)% (p < 0.003) and forward stroke volume (FSV) increased by 13.9 (18.6)% (p < 0.02). Exercise capacity was significantly improved with biventricular pacing by 48.4 (43.3)% (p < 0.00001). Regression analyses showed that the percentage increase in FSV independently predicted percentage improvement in walking distance (r(2) = 0.73, p < 0.0002). Both basal QRS duration and QRS narrowing predicted pacing efficacy, showing a significant correlation with %DeltaEDV, %DeltaESV, and %DeltaFSV.

CONCLUSIONS

In five of 15 consecutive patients with heart failure and left bundle branch block, biventricular pacing induced a more than 15% increase in FSV, which predicted a more than 25% increase in walking distance and was accompanied by an immediate reduction in left ventricular chamber size and mitral regurgitation.

Electromechanical mapping for detection of myocardial viability in patients with ischemic cardiomyopathy

BACKGROUND

We evaluated the ability of electromechanical mapping of the left ventricle to distinguish between nonviable and viable myocardium in patients with ischemic cardiomyopathy.

METHODS AND RESULTS

Unipolar voltage amplitudes and local endocardial shortening were measured in 31 patients (mean+/-SD age, 62+/-8 years) with ischemic cardiomyopathy (ejection fraction, 30+/-9%). Dysfunctional regions, identified by 3D echocardiography, were characterized as nonviable when PET revealed matched reduction of perfusion and metabolism and as viable when perfusion was reduced or normal and metabolism was preserved. Mean unipolar voltage amplitudes and local shortening differed among normal, nonviable, and viable dysfunctional segments. Coefficient of variation for local shortening exceeded differences between groups and did not allow distinction between normal and dysfunctional myocardium. Optimum nominal discriminatory unipolar voltage amplitude between nonviable and viable dysfunctional myocardium was 6.5 mV, but we observed a great overlap between groups. Individual cutoff levels calculated as a percentage of electrical activity in normal segments were more accurate in the detection of viable dysfunctional myocardium than a general nominal cutoff level. The optimum normalized discriminatory value was 68%. Sensitivity and specificity were 78% for the normalized discriminatory value compared with 69% for the nominal value (P:<0.02).

CONCLUSIONS

Endocardial ECG amplitudes in patients with ischemic cardiomyopathy display a wide scatter, complicating the establishment of exact nominal values that allow distinction between viable and nonviable areas. Individual normalization of unipolar voltage amplitudes improves diagnostic accuracy. Electroanatomic mapping may enable identification of myocardial viability.

AV block and changes in pacing mode during long-term follow-up of 399 consecutive patients with sick sinus syndrome treated with an AAI/AAIR pacemaker

This retrospective study included a large cohort of consecutive patients primarily implanted at Skejby University Hospital with an AAI/AAIR pacemaker because of sick sinus syndrome (SSS) from July 1981 to July 1999. The primary aim of the study was to analyze the risk of developing AV block during long-term follow-up. A secondary aim was to study the incidence and reasons for changes in pacing mode caused by other than AV block. A total of 399 patients (231 women, mean age 71 +/- 13.5 years) were identified. Mean follow-up was 4.6 +/- 3.4 years and occurred at death, reoperation with mode change, pacemaker explant, or end of study. During follow-up, 44 patients had a ventricular lead implanted with a mean delay of 2.8 +/- 3.1 years (range 1 day-10.4 years) after the primary implantation. A total of 30 patients received a ventricular lead because of AV block or AF with bradycardia (annual incidence 1.7%). Another 14 patients received a ventricular lead without having documented AV block or AF with pauses (annual incidence 0.8%). The present observational study documents that in patients with SSS treated with AAI/AAIR pacing, AV block requiring implantation of a ventricular lead occurs at a rate of 1.7% per year. It is considered that AAI/AAIR pacing is safe and reliable as treatment for patients with SSS and normal AV conduction.

Two mutants of human heparin binding protein (CAP37): toward the understanding of the nature of lipid A/LPS and BPTI binding

Heparin binding protein (HBP) is an inactive serine protease homologue with important implications in host defense during infections and inflammations. Two mutants of human HBP, [R23S,F25E]HBP and [G175Q]HBP, have been produced to investigate structure-function relationships of residues in the putative lipid A/lipopolysaccharide (LPS) binding site and BPTI (bovine pancreatic trypsin inhibitor) binding site. The X-ray structures have been determined at 1.9 A resolution for [G175Q]HBP and at 2.5 A resolution for the [R23S,F25E]HBP mutant, and the structures have been fully refined to R-factors of 18.2 % and 20.7 %, respectively. The G175Q mutation does not alter the overall structure of the protein, but the ability to bind BPTI has been eliminated, and the mutant mediates only a limited stimulation of the LPS-induced cytokine release from human monocytes. The lipid A/LPS binding property of [G175Q]HBP is comparable with that of native HBP. The R23S,F25E mutations do not affect the binding of lipid A/LPS and BPTI or the LPS-induced cytokine release from human monocytes. This shows that two diverse ligands, lipid A/LPS and BPTI, do not share binding sites. Previously, there was convincing evidence for the proposed lipid A/LPS binding site of HBP. Unexpectedly, the extensive structural changes introduced by mutation of Arg23 and Phe25 do not affect the binding of lipid A/LPS, indicating that another not yet identified site on HBP is involved in the binding of lipid A/LPS.

Dose-related cardiac electrophysiological effects of intravenous magnesium. A double-blind placebo-controlled dose-response study in patients with paroxysmal supraventricular tachycardia

AIMS

The role of magnesium as an antiarrhythmic drug is yet not conclusive. Therefore, we performed a double-blind, randomized, placebo-controlled dose-response study of cardiac electrophysiological effects of intravenous magnesium.

METHODS AND RESULTS

Thirty-six patients undergoing an electrophysiological evaluation for paroxysmal supraventricular tachycardia were randomized to one of the following dosages of intravenous magnesium (0, 5, 10 or 20 mmol). Conventional electrophysiological variables for sinus node function, atrial, atrioventricular node and ventricular conduction and refractoriness were measured before and after magnesium administration. Prolongation of the atrial-His interval was found at 5 mmol of magnesium compared with placebo and no further prolongation was observed at higher doses (-3 +/- 8, 11 +/- 9, 7 +/- 15, 11 +/- 16, for the dosages of 0, 5, 10 and 20 mmol of magnesium, respectively, P < 0.05). Measures of sinus node function, intra-atrial conduction and conduction through the Purkinje system were unaffected by magnesium. Male gender was associated with prolongation in atrial effective refractory period, in contrast to shortening in females: 2 +/- 43, 35 +/- 44, 36 +/- 33, 13 +/- 12 ms for males and 3 +/- 6, -12 +/- 11, -13 +/- 12, 0 +/- 23 ms for females, respectively (P < 0.001).

CONCLUSION

Atrioventricular node conduction was prolonged by 5 mmol intravenous magnesium and no further prolongation was observed at higher dosages. At dosages of 5 and 10 mmol magnesium the atrial effective refractoriness was prolonged in males and shortened in females.

Regional myocardial blood flow in patients with sick sinus syndrome randomized to long-term single chamber atrial or dual chamber pacing--effect of pacing mode and rate

OBJECTIVES

This study aimed to evaluate regional myocardial blood flow (MBF) and global left ventricular ejection fraction (LVEF) during chronic pacing in patients with sick sinus syndrome (SSS) randomized to either single chamber atrial (AAI) or dual chamber (DDD) pacing.

BACKGROUND

Experimental studies indicate that chronic pacing in the right ventricular apex changes regional MBF, thereby compromising left ventricular function.

METHODS

Thirty patients (age 74 +/- 10 years) were randomized to AAI (n = 15) or DDD (n = 15) pacemakers. After 22 +/- 7 months of pacing, MBF was quantified with 13N-labeled ammonia positron emission tomography scanning at 60 beats per min and 90 beats per min. Patients in the DDD group furthermore underwent MBF measurement at temporary AAI pacing, 60 beats per min. Myocardial blood flow was assessed in the anterior, lateral, inferior and septal regions, and the global mean MBF was calculated. Left ventricular ejection fraction was determined by echocardiography at pacemaker implantation and at the time of MBF measurements.

RESULTS

Myocardial blood flow at rates 60 and 90 beats per min did not differ between the AAI and DDD groups. During temporary AAI pacing in the DDD group, MBF was significantly higher than during DDD pacing in both the inferior (p = 0.001) and septal (p = 0.004) regions and also globally (0.61 +/- 0.15 vs. 0.53 +/- 0.13 mL x g(-1) x min(-1), p = 0.005). In the DDD group, LVEF decreased from pacemaker implantation to time of MBF measurements (0.61 +/- 0.09 vs. 0.56 +/- 0.07, p = 0.013). Left ventricular ejection fraction during temporary AAI pacing at time of MBF measurements was not different from LVEF at pacemaker implantation.

CONCLUSIONS

In patients with SSS, chronic DDD pacing reduced inferior, septal and global mean MBF as well as LVEF, as compared with temporary AAI pacing. The LVEF reversed to baseline level during temporary AAI pacing despite 22 months of permanent ventricular pacing preceding it. Augmenting pace rate to 90 beats per min increased MBF equally in the two treatment groups.

Alpha-cardiac actin is a novel disease gene in familial hypertrophic cardiomyopathy

We identified the alpha-cardiac actin gene (ACTC) as a novel disease gene in a pedigree suffering from familial hypertrophic cardiomyopathy (FHC). Linkage analyses excluded all the previously reported FHC loci as possible disease loci in the family studied, with lod scores varying between -2.5 and -6.0. Further linkage analyses of plausible candidate genes highly expressed in the adult human heart identified ACTC as the most likely disease gene, showing a maximal lod score of 3.6. Mutation analysis of ACTC revealed an Ala295Ser mutation in exon 5 close to 2 missense mutations recently described to cause the inherited form of idiopathic dilated cardiomyopathy (IDC). ACTC is the first sarcomeric gene described in which mutations are responsible for 2 different cardiomyopathies. We hypothesize that ACTC mutations affecting sarcomere contraction lead to FHC and that mutations affecting force transmission from the sarcomere to the surrounding syncytium lead to IDC.

QT dispersion in patients with arrhythmogenic right ventricular dysplasia

AIMS

Arrhythmogenic right ventricular dysplasia is a rarely diagnosed cardiomyopathy, but a frequent cause of ventricular arrhythmia and sudden cardiac death. QT interval dispersion, measured as an interlead variability of QT, is a marker of dispersion of ventricular repolarization and, hence, of electrical instability. The present study was conducted to assess the occurrence of QT dispersion and its modulation during treatment with sotalol. Methods Twenty-five patients with the diagnosis of arrhythmogenic right ventricular dysplasia were studied retrospectively. Fourteen patients were considered low risk for malignant ventricular arrhythmia and sudden cardiac death, and 11 high risk due to documented sustained ventricular arrhythmia, cardiac arrest, or sudden cardiac death. Twenty five healthy volunteers served as control subjects.

RESULTS

Dispersion of repolarization was significantly higher in patients than in control subjects (QTd and JTd: P<0.05). Dispersion of repolarization was equal in patients both with and without malignant arrhythmias. There was no significant change in dispersion after treatment with sotalol. Adjacent QT dispersion between leads V3-V4, V4-V5 and V5-V6, respectively, was higher in patients than in control subjects (P<0. 05), while no differences were seen in leads V1-V2 and V2-V3.

CONCLUSION

QT interval dispersion is increased in patients with arrhythmogenic right ventricular dysplasia. However, the degree of dispersion is not related to the severity of symptoms, nor is it influenced by treatment with sotalol.

Programming a fixed long atrioventricular delay is not effective in preventing ventricular pacing in patients with sick sinus syndrome

AIM

Most patients with sick sinus syndrome (SSS) and normal atrioventricular (AV) conduction receive dual chamber (DDDR) pacemakers. Programming a long AV delay has been proposed to avoid ventricular pacing. The present study aimed to evaluate ventricular stimulation in SSS patients with DDDR pacemakers with a long AV delay.

METHODS AND RESULTS

Thirty eight patients treated with DDDR pacemakers with a fixed long AV delay (300 ms) were studied. Data from the pacemaker event recorder were retrieved after 3 months and every year after implantation. Ten patients underwent 24 h Holter recording. Mean follow-up was 11.9 +/- 8.3 months. Median daily number of paced events in the ventricle was 2659 (25th-75th percentiles: 775-21 315) with a large inter-individual variation. The proportion of paced events in the ventricle correlated weakly with the baseline PQ interval (Spearman's rho 0.331, P = 0.043). In 12/38 patients the mean daily number of paced events in the ventricle exceeded 10,000. During 24 h Holter recording, pacemaker arrhythmias caused by repetitive retrograde atrioventricular conduction, known as VA (ventriculoatrial) conduction, occurred in five out of 10 patients.

CONCLUSION

DDDR pacing with a fixed long AV delay is inefficient in reducing ventricular pacing in one third of patients and is associated with a high risk of arrhythmias caused by repetitive retrograde AV conduction, and therefore cannot be recommended for general use in SSS patients.

Arterial thromboembolism in patients with sick sinus syndrome: prediction from pacing mode, atrial fibrillation, and echocardiographic findings

OBJECTIVE

To evaluate whether thromboembolism in sick sinus syndrome can be predicted by pacing mode, atrial fibrillation, or echocardiographic findings.

METHODS

Patients were randomised to single chamber atrial (n = 110) or ventricular (n = 115) pacing. They were divided into subgroups with and without brady-tachy syndrome at time of randomisation. The occurrence of atrial fibrillation and thromboembolism during follow up were investigated and compared with echocardiographic findings.

RESULTS

The annual risk of thromboembolism was 5.8% in patients with brady-tachy syndrome randomised to ventricular pacing, 3.2% in patients without brady-tachy syndrome randomised to ventricular pacing, 3% in patients with brady-tachy syndrome randomised to atrial pacing, and 1.5% in patients without brady-tachy syndrome randomised to atrial pacing. In atrial paced patients without brady-tachy syndrome at randomisation and without atrial fibrillation during follow up, the annual risk of thromboembolism was 1.4%. Left atrial size measured by M mode echocardiography was of no value in predicting thromboembolism.

CONCLUSIONS

Arterial thromboembolism in patients with sick sinus syndrome is very common and is associated primarily with brady-tachy syndrome at randomisation and with ventricular pacing. The risk of thromboembolism is small in atrial paced patients in whom atrial fibrillation has never been documented.

[Single-chamber atrial pacing is better than single chamber ventricular pacing in patients with sick sinus syndrome. Results of long-term follow up in a prospective randomized study]

In a study of 225 patients with sick sinus syndrome randomized to single chamber atrial pacing (n = 110) or ventricular pacing (n = 115), atrial pacing was associated with less atrial fibrillation and thromboembolism after 3.3 years follow-up. To determine whether this beneficial effect of atrial pacing is maintained at long-term, follow-up was extended. Follow-up visits were at 3 months, 12 months, and then once every year, and included physical examination, ECG, and pacemaker check-up. After 5.5 years follow-up, all-cause mortality, cardiovascular deaths, atrial fibrillation, thromboembolism, and heart failure were significantly less in the atrial group. AV block occurred in four patients in the atrial group. The beneficial effect of atrial pacing observed previously is enhanced substantially after extended follow-up. Patients with sick sinus syndrome should be treated with an atrial pacing system.

Multisite pacing as a supplemental treatment of congestive heart failure: preliminary results of the Medtronic Inc. InSync Study

This report describes the initial results of the "InSync" study, a European and Canadian multicenter trial that examines the safety and efficacy of a multisite pacemaker (Medtronic InSync) and of left ventricular pacing leads (Medtronic 2187 and 2188) implanted via a cardiac vein as a supplemental treatment of refractory congestive heart failure. Over a 10-month period, the system was implanted successfully in 68 of the 81 (84%) patients who had been enrolled in the study. The 68 patients were, on average, 66 +/- 10 years old, had a mean left ventricular ejection fraction (LVEF) = 21% +/- 9%, and 63% were in NYHA functional Class III and 37% were in Class IV. No system implant related complication occurred. During follow-up, 7 of 10 patients who exited the study had died, 4 suddenly. There was a clinical benefit among surviving patients, which was corroborated by a significant improvement in NYHA functional class and in the Minnesota Living with Heart Failure Quality of Life Questionnaire Score (MLS) and by a longer distance covered during a 6-minute walk test. This clinical improvement was associated with a significant narrowing of the paced QRS complex during biventricular pacing, a significant decrease in the interventricular mechanical delay, and a trend towards an increase in the duration of ventricular filling. These encouraging preliminary results confirm the feasibility and reliability of this new multisite pacing system in the management of dilated cardiomyopathy and support the continuation of further evaluations of this complementary treatment of refractory congestive heart failure.

Atrioventricular conduction during long-term follow-up of patients with sick sinus syndrome

BACKGROUND

It has been claimed that patients with sick sinus syndrome have an increased risk of developing AV block, but this has never been assessed prospectively. The aim of the present study was to evaluate in a prospective trial AV conduction during the long-term follow-up of patients with sick sinus syndrome.

METHODS

Two hundred twenty-five consecutive patients with sick sinus syndrome and intact AV conduction were randomized to undergo single-chamber atrial pacing (110 patients) or single-chamber ventricular pacing (115 patients). Follow-up after 3 months and then yearly included measurement of the PQ interval and, in patients with atrial pacemakers, determination of the atrial stimulus-Q intervals at pacing rates of 100 and 120 bpm. The occurrence of AV block in the atrial group was recorded. During follow-up (mean, 5.5+/-2.4 years), there was no change in PQ interval in either group and no change in atrial stimulus-Q intervals or Wenckebach block point in the atrial group. Four of 110 patients in the atrial group developed grade 2 to 3 AV block that required upgrading of the pacemaker (0.6% per year). Two of these 4 patients had right bundle-branch block at pacemaker implantation.

CONCLUSIONS

AV conduction, estimated as PQ interval and atrial stimulus-Q interval at atrial pacing rates of 100 and 120 bpm and the Wenckebach block point, remains stable during long-term follow-up. Thus, treatment with single-chamber atrial pacing is safe and can be recommended to patients with sick sinus syndrome without bundle-branch block.

A codon-based model designed to describe lentiviral evolution

A codon-based model designed to describe lentiviral evolution is developed. The model incorporates unequal base compositions in the three codon positions and selection against the CpG dinucleotide within codons to account for a deficit of this dinucleotide exhibited by lentiviral genes. The model is, to a large extent, able to account for the pattern of codon usage exhibited by the HIV1 genes gag, pol, and env, in spite of its parameter paucity. The model is extended to a similar model which operates on pentets (codons and their neighboring bases). The results obtained by the pentet model establish the importance of depression of CpGs across codon boundaries as well as within codons. The goodness of fit of the CpG depression model to the observed evolution in pairwise alignments of HIV1 sequences is assessed. The model provides a significantly better description of the observed evolution than the simpler models examined. The parameter estimates indicate that part of the unusually large biases in nucleotide frequencies observed in HIV1 genes is caused by selection against CpGs. We find that the estimates of expected numbers of substitutions, of transitions to transversions, and of synonymous to nonsynonymous substitution rates are robust to CpG depression, whereas the ratio of CpG-generating substitutions to other substitutions is strongly influenced by the choice of model.

Recovery of beat-to-beat variations of QRS

There is a growing interest in the analysis of beat-to-beat variations of the morphology (BBM) of cardiac waves in electrocardiograms (ECG). Such analyses are confronted with the low BBM-to-noise ratio. An ECG clustering technique is introduced that brings the benefits of signal averaging to BBM analysis and recovers the beat-to-beat pattern of BBM. ECG clustering aligns waves and sorts them into clusters. The precision of the alignment was enhanced by sub-sample alignment. Kohonen's self-organising neural networks identified the clusters of the cardiac waves during training. The subsequent clustering of a wave results in a label for the closest cluster, a distance to the cluster and optimal alignment. Furthermore, ECG clustering avoids base-line variations and amplitude modulation sufficiently to be applied to the QRS wave in the raw ECG. The technique is demonstrated on 14 subjects with coronary heart disease and no myocardial infarction, myocardial infarction, or inducible ventricular tachycardia. ECG clustering is a general-purpose technique for beat-to-beat analysis, where the variations are cyclic as in the sinus rhythm. Results show that beat-to-beat variations in the QRS morphology are in general cyclic, with a main period of about four cardiac cycles. All calculations were performed with the Cardio software.

[Hereditary long QT syndrome]

The Long QT Syndrome (LQTS) is a hereditary disease, characterized by a prolonged QT-interval on the electrocardiogram and a high risk of syncope and sudden death due to ventricular arrhythmias. LQTS must be suspected in apparently healthy children and young people with syncope after emotional or physical stress. Untreated symptomatic patients have a high mortality, which is markedly reduced by sympathetic block. The knowledge of the diagnostic criteria for the LQTS, a detailed history including a family history and an ECG-recording with measurement of the QT-interval in every patient with inexplicable syncope will advance the diagnosis of the LQTS and improve the survival of these patients after proper therapy. The current knowledge on the molecular genetics, epidemiology, mechanisms of arrhythmias and therapy are presented with special emphasis on the defects in the control of ionic transport over the cell membrane caused by mutations in ion channels.

Heart failure and echocardiographic changes during long-term follow-up of patients with sick sinus syndrome randomized to single-chamber atrial or ventricular pacing

BACKGROUND

In patients with sick sinus syndrome, choice of pacing mode has been implicated in the development of congestive heart failure.

METHODS AND RESULTS

A total of 225 consecutive patients with sick sinus syndrome and intact atrioventricular conduction were randomized to either single-chamber atrial pacing (n = 110) or single-chamber ventricular pacing (n = 115). Clinical assessment included New York Heart Association classification, medication, and M-mode echocardiography before pacemaker implantation, after 3 months, and subsequently once every year. At long-term follow-up (mean, 5.5+/-2.4 years), NYHA class was higher in the ventricular group than in the atrial group (NYHA class I/II/III/IV: 65/44/4/0 versus 84/22/2/1 patients, P=.010). Increase in NYHA class during follow-up was observed in 35 of 113 patients in the ventricular group versus 10 of 109 in the atrial group (P<.0005). Increase in dose of diuretics from randomization to last follow-up was significantly higher in the ventricular group than in the atrial group (21+/-49 versus 8+/-42 mg furosemide/d, P=.033). The left ventricular fractional shortening decreased significantly in the ventricular group (from 0.36+/-0.12 to 0.31+/-0.08, P<.0005) but not in the atrial group (from 0.35+/-0.13 to 0.33+/-0.09, P=.087). The left atrial diameter increased significantly in both treatment groups (ventricular group: from 34+/-7 to 41+/-7 mm, P<.0005; atrial group: from 34+/-6 to 37+/-7 mm, P=.002), but the increase was significantly higher in the ventricular group than in the atrial group (P<.0005).

CONCLUSIONS

During long-term follow-up, ventricular pacing is associated with a higher incidence of congestive heart failure and consumption of diuretics than atrial pacing. This is accompanied by a decrease in left ventricular fractional shortening and an increased dilatation of the left atrium in the ventricular paced patients.

[Arrhythmogenic right ventricular cardiomyopathy]

Arrhythmogenic right ventricular dysplasia is a rare cardiomyopathy, but a frequent cause of ventricular tachyarrhythmia and sudden cardiac death among young otherwise healthy individuals. This article contains a review of the current knowledge on epidemiology, diagnosis, symptoms and signs as well as theories on etiology and pathogenesis, prognosis and treatment. The aim is to draw attention to the disease as a cause of syncope, ventricular tachycardia and sudden cardiac death.

Long-term follow-up of patients from a randomised trial of atrial versus ventricular pacing for sick-sinus syndrome

BACKGROUND

In a previous study of 225 patients with sick-sinus syndrome randomised to either single-chamber atrial pacing (n=110) or single-chamber ventricular pacing (n=115), we found that after a mean follow-up of 3.3 years, atrial pacing was associated with significantly less atrial fibrillation and thromboembolism whereas there was no significant difference in mortality and heart failure between the two groups. We aimed to find out whether this beneficial effect of atrial pacing is maintained during extended follow-up of up to 8 years.

METHODS

Follow-up visits for all patients were at 3 months, 12 months, then once a year at which patients had a physical examination, ECG recording, and pacemaker check-up. Endpoints were mortality, cardiovascular death, atrial fibrillation, thromboembolic events, heart failure, and atrioventricular block. Data was analysed on Dec 31, 1996.

FINDINGS

At long-term follow-up, 39 patients from the atrial group had died versus 57 from the ventricular group (relative risk 0.66 [95% CI 0.44-0.99]; p=0.045). 19 patients from the atrial group and 39 patients from the ventricular group died from a cardiovascular cause (0.47 [0.27-0.82]; p=0.0065). The cumulative incidences of atrial fibrillation and chronic atrial fibrillation were also significantly lower in the atrial group than in the ventricular group (0.54 [0.33-0.89], p=0.012 and 0.35 [0.16-0.76], p=0.004, respectively). Thromboembolic events occurred in 13 patients in the atrial group and 26 in the ventricular group (0.47 [0.24-0.92], p=0.023). Heart failure was less severe in the atrial group than in the ventricular group (p<0.05). In multivariate analysis, atrial pacing was significantly associated with freedom from thromboembolic events (0.47 [0.24-0.92], p=0.028) and survival from cardiovascular death (0.52 [0.30-0.91], p=0.022), but no longer with overall survival (0.71 [0.46-1.08], p=0.11) or chronic atrial fibrillation (0.45 [0.20-1.05], p=0.063). Atrioventricular block occurred in four patients in the atrial group (0.6% annual risk).

INTERPRETATION

The beneficial effect of atrial pacing found in our previous study is enhanced substantially over time. Patients with sick-sinus syndrome should be treated with an atrial rather than ventricular-pacing system because after long-term follow-up, atrial pacing is associated with a significantly higher survival, less atrial fibrillation, fewer thromboembolic complications, less heart failure, and a low-risk of atrioventricular block.

Long-term follow-up of patients treated with implantable cardioverter defibrillators in a Danish centre. Accurrence ICD therpay and patient survivors

The aim of the this prospective follow-up study was to evaluate long-term survival and implantable cardioverter-defibrillator (ICD) therapy for ventricular tachyarrhythmias in patients treated with an ICD in a Danish centre. A total of 140 consecutive patients (112 men), of which 70.7% had coronary artery disease, received an ICD at Skejby University Hospital between March 1989 and October 1996. Mean age was 55.6 +/- 14.6 years (range 14-78 years). After implantation, 136 of the patients were followed for a median (range) of 17.7 (0.4-74.1) months. Survival, mode of death and incidence of appropriate ICD therapy and therapy due to potential life-threatening ventricular tachyarrhythmia were the main outcome measures. Kaplan-Meier plots representing total survival, cardiac death, sudden cardiac death and first episode of ICD therapy are presented. After 1, 2, 3 and 4 years, respectively, the cumulative incidences of death were 9, 18, 20 and 24%, of cardiac death 4, 11, 14 and 18%, and of sudden cardiac death 2, 3, 6 and 6%. The cumulative incidences of appropriate therapy after 1, 2, 3 and 4 years were 47, 56, 66 and 80%, respectively. The cumulative incidences of cardiac death after the first episode of appropriate therapy were 9, 11, 15 and 20% after 1, 2, 3 and 4 years, respectively. The occurrence of ICD therapy and patient survival in the present study population treated with ICD at a Danish centre was comparable to results published previously from other larger centres. The rate of sudden cardiac death was low and most of our patients received appropriate ICD therapy during follow-up, indicating correct patient selection and probable benefit of the ICD device.

Effect of residual noise level on reproducibility of the signal-averaged ECG

Late potentials are detected at various noise levels in clinical studies. The aim of this study was to assess the effect of residual noise level on the reproducibility of the signal-averaged electrocardiogram (ECG). Two consecutive raw 15-minute ECG from each of 188 patients with coronary artery disease were digitized and stored on optical discs. Each raw ECG was analyzed by two signal-averaging procedures to noise level 0.2 microV or 0.4 microV. Standard time-domain parameters were measured: QRS duration (SA-QRS), late potential (LP) duration, and root-mean-square voltage of the terminal 40 ms of the filtered QRS (RMS40). The SA-QRS was prolonged by 12 +/- 14 ms by the reduction in noise level from 0.4 microV to 0.2 microV, LP duration was prolonged by 10 +/- 10 ms, and RMS40 was reduced by 19 +/- 22 microV. The temporal variation of the measured SA-QRS from ECG1 to ECG2 was significantly lower at noise level 0.2 microV (9 +/- 13 ms) than at noise level 0.4 microV (13 +/- 14 ms) (P < .001). The LP duration was also more stable at noise level 0.2 microV than at noise level 0.4 microV (0.5 +/- 11 ms vs 2 +/- 13 ms, P < .05). The presence of any two of three abnormal parameters (SA-QRS > 120 ms, RMS40 < 25 microV, LP duration > 40 ms) was used as the criterion for the presence of LPs. At noise level 0.4 microV, the proportion of patients with diagnosed LPs in ECG1 was 25% and at noise level 0.2 microV it was 62%. At noise level 0.4 microV, 20% were reclassified from LP-negative in ECG1 to LP-positive in ECG2, and 7% were reclassified from LP-positive in ECG1 to LP-negative in ECG2. At noise level 0.2 microV, 20% were reclassified from LP-negative in ECG1 to LP-positive in ECG2, and 9% were reclassified from LP-positive in ECG1 to LP-negative in ECG2. It was concluded that (1) the diagnosis of LPs is significantly dependent on the extent of noise reduction by signal averaging: and (2) the numerical reproducibility of signal-averaged QRS duration and LP duration is lower at noise level 0.4 microV then at noise level 0.2 microV; and the diagnostic reproducibility of LPs is similar at both noise levels.

Noise in the signal-averaged electrocardiogram and accuracy for identification of patients with sustained monomorphic ventricular tachycardia after myocardial infarction

Late potentials are detected at various noise levels in clinical studies. The aim of this study was, in a case-control design, to assess the effect of residual noise level on the identification of patients with sustained monomorphic ventricular tachycardia after myocardial infarction. Electrocardiograms from 16 patients with prior myocardial infarction and documented sustained monomorphic ventricular tachycardia and 41 patients with prior myocardial infarction and without ventricular tachycardia, were analysed by two signal averaging procedures to noise level 0.2 and 0.4 muV. Standard time domain parameters were measured. Two definitions of late potential were analysed: (1) if any two of the following criteria were present (signal-averaged QRS duration > 120 ms, late potential duration > 40 ms, and root-mean-square voltage of the terminal 40 ms of the filtered QRS < 25 muV); or (2) if the signal-averaged QRS duration > or = 120 ms. Overall the signal-averaged electrocardiogram performed better at noise level 0.4 muV compared to noise level 0.2 muV with respect to identification of patients with or without ventricular tachycardia after myocardial infarction. Reducing noise level from 0.4 to 0.2 muV increased the sensitivity, but the consequence was a substantial decrease in specificity. Our data indicate that when a high sensitivity is the goal, the definition based only on signal-averaged QRS duration > or = 120 ms should be applied; sensitivity was 88% and specificity 59% at noise level 0.4 muV. If a high specificity is the goal, the definition should be based on the definition with two abnormal parameters; sensitivity was 69% and specificity 68% at noise level 0.4 muV.

[Treatment with implantable cardioverter-defibrillators. Experiences from Skejby hospital during the period 1989-1994]

The aim of the present study was to evaluate survival and therapy for ventricular tachyarrhythmia in patients treated with implantable cardioverter-defibrillator (ICD)-implantation at Skejby Hospital. Seventy-two patients, of which 54 were male, have received an ICD since 1989. Mean (range) age was 54 (16-74) years. Forty-nine (68%) had ischaemic heart disease. The patients were followed for a median (range) of 14 (1/2-50) months. Kaplan-Meyer plots are presented for total mortality, cardiac mortality, sudden cardiac mortality, appropriate therapy, and therapy for life-threatening tachyarrhythmia. After one, two and three years respectively, mortality was respectively 13, 27, and 32%, cardiac mortality was 5, 19, and 24%, sudden cardiac mortality was 3, 6, and 12%, cumulative incidence of appropriate therapy was 56, 66, and 90%, and cumulative incidence of therapy for life-threatening tachyarrhythmia was 19, 29 and 52%. It is concluded, that the majority of patients treated with an ICD developed ventricular tachyarrhythmia and had appropriate or lifesaving ICD-therapy during follow-up.

Within- and between-patient variation of the signal-averaged P wave in coronary artery disease

OBJECTIVES

To estimate interobserver, within-patient and between-patient variation of the signal-averaged P wave. To determine whether demographic, clinical, conventional ECG information, and coronary angiographic data are associated with the signal-averaged P wave duration in patients with documented coronary artery disease.

BACKGROUND

A prolonged signal-averaged P wave may indicate the presence of a substrate for atrial tachyarrhythmias and may predict subsequent development of atrial fibrillation. However, information on variation, reproducibility, and determinants of the signal-averaged P wave are sparse.

METHODS

One hundred ninety-three patients with angiographically documented coronary artery disease underwent two consecutive procedures of signal-averaging of P waves (SAECG1 and SAECG2). Interobserver, within-patient, and between-patient variation of the signal-averaged P wave was estimated (coefficient of variation: SD/mean). Multiple linear regression analysis was applied to identify parameters independently associated with signal-averaged P wave duration (SA-P). Atrial late potentials were considered if SA-P > 140 ms, and logistic regression analysis was applied to identify parameters associated with the presence of atrial late potentials.

RESULTS

The interobserver, within-patient, and between-patient coefficients of variation for the signal-averaged P wave duration were 7.5%, 6.0% and 8.4%, respectively. The signal-averaged P wave duration correlated significantly with standard ECG P wave duration and height of the patient (r = 0.59). Forty-nine percent of the patients had atrial late potentials. P wave duration in the standard ECG correctly classified 73% (140/188) of the patients with respect to atrial late potential positivity or negativity. The sensitivity was 67% and the specificity was 78%. Agreement on the presence or absence of atrial late potentials between two observers was present in 71% (136/193) of the patients, and in 78% (151/193) between SAECG1 and SAECG2.

CONCLUSIONS

The signal-averaged P wave has limited reproducibility in patients with coronary artery disease, and a normal or abnormal signal-averaged P wave can be predicted from the conventional ECG with high accuracy. It is recommended that the signal-averaged P wave be compared with the standard ECG P wave duration in follow-up studies with the aim of predicting atrial fibrillation.

The signal-averaged ECG becomes late potential-positive at low noise levels in healthy subjects

Late potentials are detected at various noise levels in clinical studies. The aim of this study was to quantify the effect of residual noise level on the signal-averaged ECG. Thirty minutes of raw ECG (lead -X, +X, -Y, +Y, -Z, and +Z) from 10 healthy volunteers were digitized and stored on optical discs. Each ECG was analysed by four signal averaging procedures to noise level 0.1, 0.2, 0.3, and 0.4 microV, respectively. At each noise level, time domain analysis of the filtered vector (40-250 Hz) included determination of the QRS duration (QRS), late potential duration (LPD, duration of terminal signals below 40 microV), and root-mean-square voltage of the terminal 40 ms of the filtered QRS (RMS40). On average, the measured signal-averaged QRS duration was prolonged by 7.0 ms (range 0.9-12.5 ms) per 0.1 microV reduction in noise level. Late potential duration increased by 5.9 ms (range 0.2-10.0 ms) per 0.1 microV reduction in noise level, and RMS40 was reduced by 9.1 microV (range 0.5-20.2 microV) per 0.1 microV reduction in noise level. At noise level 0.4 microV, 0.3 microV, 0.2 microV, and 0.1 microV the number of late potential-positive subjects were 1, 2, 4, and 6, respectively. Late potential parameters are significantly dependent on noise level after signal averaging. Using conventional criteria for late potentials, healthy subjects become false-positive at low noise levels. Establishment of standards for noise level is recommended.

Comparison among opsonic activity, antimeningococcal immunoglobulin G response, and serum bactericidal activity against meningococci in sera from vaccinees after immunization with a serogroup B outer membrane vesicle vaccine

Opsonic activity in sera from 27 military recruits vaccinated with the Norwegian meningococcal serogroup B outer membrane vesicle vaccine was measured as respiratory burst with polymorphonuclear leukocytes as the effector cells and meningococci of the epidemic strain as the target. The results were compared with antimeningococcal IgG antibodies against an outer membrane vesicle coat in an enzyme-linked immunosorbent assay and with serum bactericidal activity. The vaccinees were immunized twice, with a 6-week interval between the two. The serum samples studied were collected at day zero, after 6 weeks, and after 12 weeks. Both serum bactericidal activity and respiratory burst were measured by adding external serum as the complement source. The results revealed a significant increase in specific IgG response, serum bactericidal activity, and respiratory burst after vaccination. We found a highly significant correlation between the responses in all three assays (P < 0.0001). The highest correlation was found between respiratory burst and antimeningococcal IgG response (r = 0.93). This result strongly indicates that respiratory burst is mediated almost exclusively by IgG antibodies. The correlation between antimeningococcal IgG response and serum bactericidal activity was slightly lower (r = 0.83). The correlation between respiratory burst and serum bactericidal activity was further reduced (r = 0.78), and some of the sera revealed a marked preference for only one of the activities. This result means that respiratory burst and serum bactericidal activity in part are induced by different mediators, and to obtain a more complete picture of the potential protective activity, both assays should be applied to survey a vaccine trial.

[Late ventricular potentials after myocardial infarction]

Late potentials in the QRS complex can be detected with signal-averaged electrocardiography and are associated with delayed and disorganized ventricular activation. This article reviews the technique, describes the pathophysiological basis of late potentials, and assesses the prognostic value of late potentials for subsequent development of ventricular tachyarrhythmias and sudden cardiac death in postmyocardial infarction patients.

Complete fracture-dislocation of the atlantoaxial complex: case report and recommendations for a new classification of dens fractures

A 77-year-old man fell and sustained a fracture-dislocation of the atlantoaxial complex with 20 mm of posterior displacement. Initial and repeat examinations failed to diagnose the fracture-dislocation, which was first diagnosed by a magnetic resonance imaging study 16 weeks after the injury and after the patient had developed a profound myelopathy. The patient was treated by a C2 decompressive laminectomy and an in situ posterior fusion with iliac bone graft and internal fixation with gradual resolution of his myelopathy. Postoperatively he developed respiratory problems and persistent difficulties swallowing, believed to be at least partly due to cranial nerve involvement. A new classification system for dens fractures is suggested.

Effects of fish oil supplementation in the third trimester of pregnancy on prostacyclin and thromboxane production

OBJECTIVE

Disturbance in thromboxane and prostacyclin biosynthesis has been observed in preeclampsia. We studied whether fish oil supplementation in late pregnancy interferes with maternal and fetal production of thromboxane A2 and prostacyclin I2.

STUDY DESIGN

Forty-seven women in the thirtieth week of pregnancy were randomly assigned in a ratio of 2:1:1 to receive fish oil (2.7 gm of n-3 fatty acid per day [Pikasol], or either olive oil or no oil supplementation as controls. Metabolites of thromboxane A2 and A3 and of prostacyclin I2 and I3 were quantified by mass spectrometry methods in serum and urine, respectively. Maternal serum and urine were sampled at baseline, in the thirty-third and thirty-seventh weeks of pregnancy. Fetal serum was sampled at delivery.

RESULTS

At the thirty-seventh week the mean concentrations of the eicosapentaenoic-derived metabolites, thromboxane B3 and prostacyclin I3, was twofold to threefold higher (p < 0.001) in the group receiving fish oil compared with combined control groups. There were no significant effects of fish oil on the prostacyclin I2 metabolite, although there was a trend toward a reduction in thromboxane B2 in this group. In umbilical cord blood the mean concentration of thromboxane B2 was lowest in the group receiving fish oil (p = 0.03).

CONCLUSIONS

Fish oil was metabolized to the eicosapentaenoic acid-derived eicosanoids thromboxane A3 and prostacyclin I3 in pregnant women. Correspondingly, analog products of arachidonic acid tended to be depressed. It remains to be established whether these biochemical effects will prove beneficial in the prevention or treatment of preeclampsia and intrauterine growth retardation.

A posteroseptal accessory pathway located in a coronary sinus aneurysm: diagnosis and radiofrequency catheter ablation

A coronary sinus aneurysm was diagnosed by means of echocardiography, coronary sinus contrast angiography, coronary angiography, and nuclear magnetic resonance imaging in a patient with Wolff-Parkinson-White syndrome caused by a posteroseptal accessory pathway. Percutaneous radiofrequency current catheter ablation performed in the isthmus of the coronary sinus aneurysm was successful.

Nonpharmacologic treatment of supraventricular and ventricular tachyarrhythmias. A review of 249 consecutive patients

Incapacitating or life-threatening tachyarrhythmias were treated nonpharmacologically in 249 patients from 1982 to 1991. Among 92 patients surgically treated for supraventricular tachycardia the cure rate was 93% and the complication rate 12%. Radiofrequency catheter ablation gave an equal cure rate in 51 patients, but with no major complications or mortality. Direct-current catheter ablation of the His bundle was successful in 96% of 27 patients with drug-refractory atrial fibrillation or other supraventricular tachyarrhythmias. Among 64 patients undergoing surgery for ventricular tachycardia/ventricular fibrillation, the perioperative mortality was 9%, estimated 5-year survival 69% and estimated 5-year freedom from the preoperative arrhythmias 72%. Of 18 patients treated with implantable cardioverter defibrillator, three (18%) died of heart failure during follow-up. Nonpharmacologic treatment of tachyarrhythmias is concluded to be effective and often definitively curative. The safety-risk ratio is improving as new treatment modalities are developed.

Antiischemic and metabolic effects of glutamate during pacing in patients with stable angina pectoris secondary to either coronary artery disease or syndrome X

The effects of glutamate on anginal threshold, cardiac metabolism and hemodynamics were studied in 11 patients with stable angina pectoris, positive stress test results, and pacing-induced myocardial lactate release due to coronary artery disease (CAD) (n = 9) or syndrome X (n = 2). Data were obtained before, during and after 2 identical periods of coronary sinus pacing, the second being preceded by an intravenous injection of monosodium glutamate 1.2 (n = 7) or 2.5 (n = 4) mg/kg body weight. After glutamate administration, pacing time to onset of angina increased from mean +/- standard deviation 103 +/- 53 to 166 +/- 71 seconds (p less than 0.01) and ST-segment depression after pacing decreased from 2.3 +/- 1.0 to 1.6 +/- 1.1 mm (p less than 0.01). Arterial glutamate concentration increased 60% (p less than 0.01) after the low dose and 150% (p less than 0.01) after the high dose of glutamate. Regardless of dose, myocardial glutamate uptake increased by 25% (p less than 0.01). Pacing-induced cardiac release of lactate diminished 50% (p less than 0.05), whereas the releases of xanthine and hypoxanthine were unchanged by glutamate. Arterial free fatty acids decreased 20% (p less than 0.01). Circulating levels and cardiac exchanges of alanine, glucose and citrate were unchanged. Glutamate did not influence heart rate, arterial blood pressure, coronary blood flow, coronary vascular resistance or myocardial oxygen consumption. One patient complained of short-lasting burning sensations after receiving the high glutamate dose. In conclusion, augmented provision of glutamate enhances pacing tolerance in stable angina, presumably by a metabolic improvement of cardiac energy production during ischemia.

Flecainide acetate in atrial flutter and fibrillation. The arrhythmogenic effects

The arrhythmogenic effects of flecainide in atrial fibrillation and flutter were assessed in a consecutive material of 100 patients without severe heart failure (NYHA class I or II). Severe arrhythmogenic events occurred in 9% (4-16%) of the patients: within the first 5 days of treatment in seven patients, and in two patients after 60 and 240 days of flecainide treatment. Patients with proarrhythmic events tended to be older and to have a longer QRS duration. Following flecainide therapy conversion to sinus rhythm was achieved in 21 of 43 patients (49%) with atrial fibrillation and in 10 of 29 (34%) with atrial flutter. It is concluded that flecainide, although an effective antiarrhythmic drug, has potential proarrhythmic effects and therefore cautious use of this drug is mandatory.