Physical activity measures in patients with myalgic encephalomyelitis/chronic fatigue syndrome: correlations between peak oxygen consumption, the physical functioning scale of the SF-36 questionnaire, and the number of steps from an activity meter.

BACKGROUND: Most studies to assess effort intolerance in patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) have used questionnaires. Few studies have compared questionnaires with objective measures like an actometer or an exercise test. This study compared three measures of physical activity in ME/CFS patients: the physical functioning scale (PFS) of the SF-36, the number of steps/day (Steps) using an actometer, and the %peak VO2 of a cardiopulmonary stress test. METHODS: Female ME/CFS patients were selected from a clinical database if the three types of measurements were available, and the interval between measurements was ≤ 3 months. Data from the three measures were compared by linear regression. RESULTS: In 99 female patients the three different measures were linearly, significantly, and positively correlated (PFS vs Steps, PFS vs %peak VO2 and Steps vs %peak VO2: all P < 0.001). Subgroup analysis showed that the relations between the three measures were not different in patients with versus without fibromyalgia and with versus without a maximal exercise effort (RER ≥ 1.1). In 20 patients re-evaluated for symptom worsening, the mean of all three measures was significantly lower (P < 0.0001), strengthening the observation of the relations between them. Despite the close correlation, we observed a large variation between the three measures in individual patients. CONCLUSIONS: Given the large variation in ME/CFS patients, the use of only one type of measurement is inadequate. Integrating the three modalities may be useful for patient care by detecting overt discrepancies in activity and may inform studies that compare methods of improving exercise capacity.

Effects of high-dose insulin infusion on left ventricular function in normal subjects.

Background. Only a few studies have reported on the effect of high-dose insulin (HDI) infusion on cardiac function in healthy volunteers. Methods. We studied ten healthy volunteers with low-dose dobutamine (LDD, 10 mug/kg/min) echo-cardio-graphy and HDI echocardiography (insulin administration for one hour) by volume and Doppler analysis. Results. During LDD, cardiac output increased from 5.7+/-1.3 l/min to 9.0+/-2.1 l/min (p<0.001) and during HDI from 5.5+/-1.2 l/min to 6.2+/-1.1 l/min (p=0.048). Increase was not only due to increase in frequency, which was only present in the LDD study, but also due to increase in stroke volume (from 82+/-15 ml to 110+/-23 ml, p<0.001 during LDD and from 82+/-16 ml to 93+/-24 ml, p=0.014 during HDI). The increase in stroke volume was the result of a decrease in end-systolic volume with an unchanged end-diastolic volume. Conclusion. High-dose insulin infusion results in increased cardiac output by improving systolic myocardial function. (Neth Heart J 2010;18:183-9.).

FDG PET as a predictor of response to resynchronisation therapy in patients with ischaemic cardiomyopathy.

PURPOSE: Although resynchronisation therapy (CRT) is a promising addition to heart failure therapy, a substantial number of patients do not respond to CRT. As FDG PET has routinely been used for prediction of improvement after revascularisation in ischaemic cardiomyopathy, it was hypothesised that there is also a relationship between the extent of viable tissue and improvement as a result of CRT. METHODS: Thirty-nine patients with ischaemic cardiomyopathy (ejection fraction 27 +/- 9%) and a wide QRS complex underwent temporary pacing to determine the optimal pacing combination, i.e. that with the highest increase in cardiac index (CI) compared with baseline (measured by Doppler echocardiography). All patients also underwent FDG PET imaging. In 19 patients, CI measurements were repeated 10-12 weeks after permanent biventricular pacemaker implantation. RESULTS: Echocardiography (13-segment model) showed a mean of 9.8 +/- 1.6 dyssynergic segments, with preserved FDG uptake in 4.1 +/- 2.4 segments. CI improvement at the optimal pacing site was 20 +/- 9%. There was a linear relationship between the extent of viable tissue and CI improvement during pacing (p < 0.001). Using a cut-off value of more than three viable segments (ROC analysis), FDG PET had a sensitivity of 72% and a specificity of 71% for detection of the presence of haemodynamic improvement (i.e. a CI improvement >15%). The relation between CI improvement and viable tissue was similar at follow-up. CONCLUSION: A correlation was found between the extent of viable tissue and the haemodynamic response to CRT in patients with ischaemic cardiomyopathy, suggesting that FDG PET imaging may be useful to discriminate between responders and non-responders to CRT.

Comparison of the haemodynamics of different pacing sites in patients undergoing resynchronisation treatment: need for individualisation of lead localisation.

BACKGROUND: Biventricular pacing is a new therapy for the treatment of heart failure. However, a substantial number of patients do not respond to this therapy. HYPOTHESIS: Individually determined maximal pacing sites will improve the haemodynamic response and increase the number of responders. METHODS: In 48 patients with heart failure, the acute haemodynamic effects of nine different pacing configurations were studied, using two right and left ventricular pacing sites and their combinations. Cardiac index was measured using Doppler echocardiography. For further analysis, the combination with the highest cardiac index improvement was compared with baseline. Moreover, the number of responders was calculated using a cut-off value of 10% increase in cardiac index. RESULTS: The mean (SD) increase in cardiac index ranged between 3.8% (6.0%) and 11.1% (8.6%). The pacing site with maximal cardiac index was highly variable between patients, and here the cardiac index increased to 14.8% (7.6%; (p<0.001). The number of responders varied between 15% and 64%, increasing to 75% at the site with maximal increase in cardiac index. In a subset of patients, the haemodynamic improvement after pacemaker implantation correlated well with the acute haemodynamics. CONCLUSION: Individualisation of pacing configuration for biventricular pacing leads to further haemodynamic improvement in patients with heart failure and reduces the number of patients not responding to this therapy.

Major dissection of the coronary sinus and its tributaries during lead implantation for biventricular stimulation: angiographic follow-up.

Dissection of the coronary sinus during lead implantation for biventricular pacemaker implantation in patients with advanced heart failure is a serious complication that has occasionally been reported. We report on the clinical outcome and angiographic follow-up in a series of 7 patients with acute major dissection from 103 consecutive attempts (incidence 6.8%). Serial echocardiography was performed in all patients and all underwent follow-up angiography 2-3 months after the procedure. In 1 patient, pericardial extravasation was seen during retrograde venography. Clinical follow-up was uneventful except for one other patient who complained of prolonged chest discomfort for several hours after the procedure. In none of the patients were there signs of pericardial effusion or tamponade demonstrated on echocardiography. Venograms during the procedure and after follow-up were analysed using a quantitative coronary angiography system (CAAS II). Parameters included minimal luminal diameter, diameter stenosis, minimal cross-sectional area and an estimation of the reference diameter. There were no significant differences in all analysed parameters, although in 1 patient a small partial dissection was present. Thus, although dissection of the coronary sinus following lead implantation for biventricular stimulation is not an uncommon complication, it is usually well tolerated. Long-term angiographic follow-up demonstrated no significant vessel damage or vessel remodeling.

Utility and safety of prolonged temporary transvenous pacing using an active-fixation lead: comparison with a conventional lead.

Transvenous temporary pacing is associated with a substantial dislocation rate reported to range from 10 to 37%. The aim of the study was to assess the safety and utility of a recently introduced 3.5 Fr temporary pacing lead using active fixation in a consecutive series of 36 patients with prolonged (> or = 48 hours) transvenous temporary pacing (validation group). A group of 36 patients with prolonged transvenous pacing managed with a passive-fixation lead just prior to the introduction of the active-fixation lead served as a control group (reference group). Pacing related adverse events included dislocation, inappropriate pacing (i.e., two-fold or greater increase of initial pacing threshold), local infection, and thrombosis. There were no significant differences in patient characteristics or duration of pacing (5.84 +/- 2.4 days in the reference group vs 5.94 +/- 2.6 days in the validation group). Acute pacing threshold was significantly higher in the validation group as compared to the reference group (1.38 +/- 0.67 V vs. 0.7 +/- 0.21 V, P < 0.01). The dislocation rate was significantly lower in the validation group as compared to the reference group (5.5 vs 33.3%, P < 0.001). There were 11 (31%) pacing related adverse events in the validation group versus 21 (58%) in the reference group (P < 0.01). The vast majority of patients in the validation group (75%) had ambulatory temporary pacing. Thus, transvenous temporary pacing using active fixation is safe and is associated with a low dislocation rate and a reduction in pacing related adverse events.

Successful percutaneous extraction of an inadvertently placed left ventricular pacing lead.

A 74-year-old patient was referred for a rapidly increasing pacing threshold 9 months after DDD pacemaker implantation because of symptomatic total atrioventricular (AV) block. She had a history of hypertension, diabetes with micro-angiopathy and a recent transient ischaemic attack. The paced electrocardiogram on admission had a right bundle branch block pattern and 3-dimensional transoesophageal echocardiography demonstrated passage of the lead through an atrial septal defect with a left ventricular position in addition to moderate atherosclerosis of the ascending aorta. No thrombus could be detected on the lead. Percutaneous extraction is usually not recommended because of the risk of mobilization of thrombus material. However, the risk of stroke during removal using cardiopulmonary bypass in this patient was considerably increased because of the presence of multiple independent risk factors. Therefore, percutaneous extraction using a locking device was selected and performed without complications: follow-up was uneventful.