Cryoablation as standard treatment of atrial flutter: a prospective, 2-center study (CASTAF).

BACKGROUND: Cryoablation (CRYO) of cavotricuspid isthmus (CTI)-dependent atrial flutter (AFL) has been shown to be non-inferior to radiofrequency ablation (RF) in terms of ablation success and is associated with less pain. However, procedural time has been significantly longer with CRYO compared to RF. A possible explanation for this could be that operators had less experience with CRYO than with RF. The purpose of this study was to test the hypothesis that in the hands of experienced operators, cryoablation of CTI-dependent AFL is effective with procedure-time similar to what is reported for RF. METHODS: This prospective 2-center study included 184 patients with CTI-dependent AFL - median age 66 years (range 28-83), 159 men (86%). Cryoablation was performed using a 9 F, 8 mm tip catheter (Freezor MAX, Medtronic, Inc, MN, USA). Ablation endpoint was bidirectional CTI-block. Pain was evaluated with a visual analogue scale (VAS 0-10). All operators had experience of at least 25 previous CTI-ablations with CRYO. RESULTS: The acute success rate was 89%. Procedural time including an observation period of 30 min, was 115 ± 36 min which is similar to procedural times for RF in previous studies. Fluoroscopy time was 11 ± 9 min. Cryoablation was perceived as almost pain- free by the patients, VAS (mean) 1.8 ± 1.2. Success rate at 12-month follow-up (FU) was 88% in patients with primary success. No major adverse events occurred. CONCLUSIONS: Cryoablation of CTI-dependent AFL is effective, with a low level of procedure-related pain. In experienced hands, the procedure time in this prospective non-randomised trial seems to be in the level of reported procedure times for RF. The long-term relapse rate appears to be higher than for RF.

Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: Role of mitochondrial oxygen affinity.

AIM: We examined the Fick components together with mitochondrial O2 affinity (p50mito ) in defining O2 extraction and O2 uptake during exercise with large and small muscle mass during normoxia (NORM) and hyperoxia (HYPER). METHODS: Seven individuals performed 2 incremental exercise tests to exhaustion on a bicycle ergometer (BIKE) and 2 on a 1-legged knee extension ergometer (KE) in NORM or HYPER. Leg blood flow and VO2 were determined by thermodilution and the Fick method. Maximal ADP-stimulated mitochondrial respiration (OXPHOS) and p50mito were measured ex vivo in isolated mitochondria. Mitochondrial excess capacity in the leg was determined from OXPHOS in permeabilized fibres and muscle mass measured with magnetic resonance imaging in relation to peak leg O2 delivery. RESULTS: The ex vivo p50mito increased from 0.06 ± 0.02 to 0.17 ± 0.04 kPa with varying substrate supply and O2 flux rates from 9.84 ± 2.91 to 16.34 ± 4.07 pmol O2 ·s-1 ·µg-1 respectively. O2 extraction decreased from 83% in BIKE to 67% in KE as a function of a higher O2 delivery and lower mitochondrial excess capacity. There was a significant relationship between O2 extraction and mitochondrial excess capacity and p50mito that was unrelated to blood flow and mean transit time. CONCLUSION: O2 extraction varies with mitochondrial respiration rate, p50mito and O2 delivery. Mitochondrial excess capacity maintains a low p50mito which enhances O2 diffusion from microvessels to mitochondria during exercise.

Superselective endovascular tissue access using trans-vessel wall technique: feasibility study for treatment applications in heart, pancreas and kidney in swine.

OBJECTIVES: With the emergence of targeted cell transplantation and gene therapy, there is a need for minimally invasive tissue access to facilitate delivery of therapeutic substrate. The objective of this study was to demonstrate the suitability of an endovascular device which is able to directly access tissue and deliver therapeutic agent to the heart, kidney and pancreas without need to seal the penetration site. METHODS: In vivo experiments were performed in 30 swine, including subgroups with follow-up to evaluate complications. The previously described trans-vessel wall (VW) device was modified to be sharper and not require tip detachment to seal the VW. Injections into targets in the heart (n = 13, 24-h follow-up n = 5, 72-h follow-up n = 3), kidney (n = 8, 14-day follow-up n = 3) and pancreas (n = 5) were performed. Some animals were used for multiple organ injections. Follow-up consisted of clinical monitoring, angiography and necropsy. Transvenous (in heart) and transarterial approaches (in heart, kidney and pancreas) were used. Injections were targeted towards the subepicardium, endomyocardium, pancreas head and tail, and kidney subcapsular space and cortex. RESULTS: Injections were successful in target organs, visualized by intraparenchymal contrast on fluoroscopy and by necropsy. No serious complications (defined as heart failure or persistent arrhythmia, haemorrhage requiring treatment or acute kidney injury) were encountered over a total of 157 injections. CONCLUSIONS: The trans-VW device can achieve superselective injections to the heart, pancreas and kidney for delivery of therapeutic substances without tip detachment. All parts of these organs including the subepicardium, pancreas tail and renal subcapsular space can be efficiently reached.

Why do arms extract less oxygen than legs during exercise?

To determine whether conditions for O2 utilization and O2 off-loading from the hemoglobin are different in exercising arms and legs, six cross-country skiers participated in this study. Femoral and subclavian vein blood flow and gases were determined during skiing on a treadmill at approximately 76% maximal O2 uptake (V(O2)max) and at V(O2)max with different techniques: diagonal stride (combined arm and leg exercise), double poling (predominantly arm exercise), and leg skiing (predominantly leg exercise). The percentage of O2 extraction was always higher for the legs than for the arms. At maximal exercise (diagonal stride), the corresponding mean values were 93 and 85% (n = 3; P < 0.05). During exercise, mean arm O2 extraction correlated with the P(O2) value that causes hemoglobin to be 50% saturated (P50: r = 0.93, P < 0.05), but for a given value of P50, O2 extraction was always higher in the legs than in the arms. Mean capillary muscle O2 conductance of the arm during double poling was 14.5 (SD 2.6) ml.min(-1).mmHg(-1), and mean capillary P(O2) was 47.7 (SD 2.6) mmHg. Corresponding values for the legs during maximal exercise were 48.3 (SD 13.0) ml.min(-1).mmHg(-1) and 33.8 (SD 2.6) mmHg, respectively. Because conditions for O2 off-loading from the hemoglobin are similar in leg and arm muscles, the observed differences in maximal arm and leg O2 extraction should be attributed to other factors, such as a higher heterogeneity in blood flow distribution, shorter mean transit time, smaller diffusing area, and larger diffusing distance, in arms than in legs.

Maximal muscular vascular conductances during whole body upright exercise in humans.

That muscular blood flow may reach 2.5 l kg(-1) min(-1) in the quadriceps muscle has led to the suggestion that muscular vascular conductance must be restrained during whole body exercise to avoid hypotension. The main aim of this study was to determine the maximal arm and leg muscle vascular conductances (VC) during leg and arm exercise, to find out if the maximal muscular vasodilatory response is restrained during maximal combined arm and leg exercise. Six Swedish elite cross-country skiers, age (mean +/-s.e.m.) 24 +/- 2 years, height 180 +/- 2 cm, weight 74 +/- 2 kg, and maximal oxygen uptake (VO(2,max)) 5.1 +/- 0.1 l min(-1) participated in the study. Femoral and subclavian vein blood flows, intra-arterial blood pressure, cardiac output, as well as blood gases in the femoral and subclavian vein, right atrium and femoral artery were determined during skiing (roller skis) at approximately 76% of VO(2,max) and at VO(2,max) with different techniques: diagonal stride (combined arm and leg exercise), double poling (predominantly arm exercise) and leg skiing (predominantly leg exercise). During submaximal exercise cardiac output (26-27 l min(-1)), mean blood pressure (MAP) (approximately 87 mmHg), systemic VC, systemic oxygen delivery and pulmonary VO2(approximately 4 l min(-1)) attained similar values regardless of exercise mode. The distribution of cardiac output was modified depending on the musculature engaged in the exercise. There was a close relationship between VC and VO2 in arms (r= 0.99, P < 0.001) and legs (r= 0.98, P < 0.05). Peak arm VC (63.7 +/- 5.6 ml min(-1) mmHg(-1)) was attained during double poling, while peak leg VC was reached at maximal exercise with the diagonal technique (109.8 +/- 11.5 ml min(-1) mmHg(-1)) when arm VC was 38.8 +/- 5.7 ml min(-1) mmHg(-1). If during maximal exercise arms and legs had been vasodilated to the observed maximal levels then mean arterial pressure would have dropped at least to 75-77 mmHg in our experimental conditions. It is concluded that skeletal muscle vascular conductance is restrained during whole body exercise in the upright position to avoid hypotension.

Influence of glucose control, lipoproteins, and haemostasis function on brachial endothelial reactivity and carotid intima-media area, stiffness and diameter in Type 1 diabetes mellitus patients.

BACKGROUND: The objectives of this study were to determine the influence of glucose control on lipoprotein and haemostasis variables in Type 1 diabetes mellitus patients and to evaluate the global impact of these metabolic risk factors on brachial artery reactivity and carotid artery atherosclerosis, stiffness and diameter. DESIGN: Follow up of Type 1 diabetes patients randomized to insulin-intensive conventional treatment (ICT, n = 29) or insulin-standard treatment (ST, n = 25) in the Stockholm Diabetes Intervention Study (SDIS) more than 14 years ago. RESULTS: The intensive conventional treatment patients had lower glycosylated haemoglobin (HbA1c) compared with the ST patients, i.e. 7.01 (SD 0.51) vs. 8.31 (0.97), while concentrations of the lipoprotein and haemostasis variables analyzed were virtually similar. The carotid artery intima-media area was associated with high HbA1c, high serum (S)-cholesterol levels, and low high-density lipoprotein (HDL)-cholesterol levels. Carotid artery stiffness was associated with high systolic blood pressure, high HbA1c, high fibrinogen, and high HDL-cholesterol. Brachial artery endothelial reactivity was higher for women and those with low S-cholesterol. CONCLUSION: In patients with Type 1 diabetes, glucose control appeared to have no effect on either lipoproteins or haemostasis variable concentrations. Poor glucose control, and high levels of S-cholesterol, systolic blood pressure and plasma fibrinogen were associated with development of atherosclerosis, thus emphasising the importance of global risk factor control in patients with Type 1 diabetes mellitus.

Leg and arm lactate and substrate kinetics during exercise.

To study the role of muscle mass and muscle activity on lactate and energy kinetics during exercise, whole body and limb lactate, glucose, and fatty acid fluxes were determined in six elite cross-country skiers during roller-skiing for 40 min with the diagonal stride (Continuous Arm + Leg) followed by 10 min of double poling and diagonal stride at 72-76% maximal O(2) uptake. A high lactate appearance rate (R(a), 184 +/- 17 micromol x kg(-1) x min(-1)) but a low arterial lactate concentration ( approximately 2.5 mmol/l) were observed during Continuous Arm + Leg despite a substantial net lactate release by the arm of approximately 2.1 mmol/min, which was balanced by a similar net lactate uptake by the leg. Whole body and limb lactate oxidation during Continuous Arm + Leg was approximately 45% at rest and approximately 95% of disappearance rate and limb lactate uptake, respectively. Limb lactate kinetics changed multiple times when exercise mode was changed. Whole body glucose and glycerol turnover was unchanged during the different skiing modes; however, limb net glucose uptake changed severalfold. In conclusion, the arterial lactate concentration can be maintained at a relatively low level despite high lactate R(a) during exercise with a large muscle mass because of the large capacity of active skeletal muscle to take up lactate, which is tightly correlated with lactate delivery. The limb lactate uptake during exercise is oxidized at rates far above resting oxygen consumption, implying that lactate uptake and subsequent oxidation are also dependent on an elevated metabolic rate. The relative contribution of whole body and limb lactate oxidation is between 20 and 30% of total carbohydrate oxidation at rest and during exercise under the various conditions. Skeletal muscle can change its limb net glucose uptake severalfold within minutes, causing a redistribution of the available glucose because whole body glucose turnover was unchanged.

Risk factors for coronary heart disease in 55- and 35-year-old men and women in Sweden and Estonia.

OBJECTIVE: To illustrate the geographical West-to-East division of coronary heart disease (CHD) by comparing a population from Sweden, that represents a Western country to a population from Estonia, that represents an Eastern country. Estonia has an approximately 2-4-fold higher CHD prevalence for 55-year-old women and men, respectively, than Sweden. DESIGN: Randomized screening of 35- and 55-year-old men and women in Sollentuna county, Sweden and Tartu county, Estonia. Eight hundred subjects, 100 from each cohort, were invited to participate in the study, 272 Swedes and 277 Estonians participated. SETTING: Preventive cardiology, administered by a primary health care centre at the Karolinska Hospital, Sweden and a cardiology centre at Tartu University Hospital, Estonia. MAIN OUTCOME MEASURES: The CHD risk factors (smoking, blood pressure, concentrations of lipoproteins, fibrinogen, and glucose) and certain environmental factors and attitudes related to CHD risk by questionnaires (fat-type and alcohol ingestion, self-assessed rating of CHD susceptibility). RESULTS: Of the 55-year-old men, 57% smoked in Estonia and 20% smoked in Sweden. Similar, although less pronounced differences showing higher smoking prevalence, were seen for 35-year-old Estonian men and women, whilst for 55-year-old women, less than 20% smoked in either country. Estonian 55-year-old women had lower HDL cholesterol and higher LDL cholesterol serum concentrations than Swedish 55-year-old women. Estonians reportedly ate food containing more saturated fats than Swedes, as indicated by the scale-score questionnaire. Estonians, relative to Swedes, rated their chance of developing CHD higher, and paradoxically, Estonians did to a much lesser degree believe that life style influences the risk of developing CHD. CONCLUSIONS: Elevated smoking prevalence is a striking difference between the Estonian and Swedish populations likely to explain the much higher CHD prevalence in Estonian men. The lower HDL cholesterol and higher LDL cholesterol in Estonian 55-year-old women may explain the higher CHD prevalence in Estonian women. Furthermore, the SWESTONIA CHD study (i.e. comparison between Sweden and Estonia) shows several environmental differences between the countries populations related to fat content in food, alcohol drinking patterns, and views on CHD risk and the importance of lifestyle intervention, that could contribute to the higher CHD prevalence in Estonia.

Left ventricular diastolic function is related to glucose in a middle-aged population.

OBJECTIVES: To examine the relation between left ventricular (LV) diastolic function and glucose metabolism in individuals without previously diagnosed diabetes mellitus. DESIGN: A cross-sectional population-based study. SETTING: A university hospital. SUBJECTS: Thirty-five men and women 56-58 years of age without previously diagnosed diabetes or heart disease. MAIN OUTCOME MEASURES: Left ventricular diastolic function assessed by pulsed Doppler tissue imaging and its relation to fasting plasma glucose, glucose postload and glycated haemoglobin. LV diastolic function was determined by measuring early diastolic filling peak velocity (Em wave cm s-1), late diastolic filling peak velocity (Am wave cm s-1) and their ratio Em/Am. RESULTS: Peak Em velocity, peak Am velocity and their ratio Em/Am correlated with fasting plasma glucose (r=-0.42, P=0.01; r=0.47, P=0.04 and r=-0.53, P=0.001, respectively). There was a correlation between peak Em velocity, the ratio of Em/Am and glycated haemoglobin. LV diastolic function was also related to glucose postload. CONCLUSIONS: Left ventricular diastolic function is related to concentrations of fasting plasma glucose, glucose postload and glycated haemoglobin even below the threshold of diabetes. This indicates that glucose concentrations already in the upper end of the normal range has negative impact on cardiac function.

Spontaneous delayed recovery of perfusion after thrombolyzed acute myocardial infarction: is it predictable before discharge?

In patients with thrombolyzed acute myocardial infarction, early assessment of the final infarct size is difficult because spontaneous recovery of perfusion and function of the left ventricle may be delayed. This study was undertaken to evaluate the ability of predischarge low-dose dobutamine echocardiography to predict late spontaneous recovery of perfusion assessed by single-photon emission computed tomography after acute myocardial infarction. We prospectively studied 53 consecutive patients with myocardial infarction treated with thrombolysis. Low-dose dobutamine echocardiography and resting (99m)Tc-sestamibi single-photon emission computed tomography (MIBI SPECT) were performed 4 +/- 2 days after infarction. A follow-up SPECT study was carried out in 45 patients after 6 months. Myocardial recovery was defined as a reduction of SPECT defect size by more than 10% at follow-up compared with the early study. In 25 of the 45 patients, the size of the left ventricular perfusion defect decreased significantly from 42% +/- 16% to 27% +/- 10% (group 1), whereas in the remaining 20 patients it showed no significant change (group 2). Predischarge low-dose dobutamine echocardiography showed a significant improvement in wall motion score index compared with baseline in group 1, from 1.62 +/- 0.28 to 1.41 +/- 0.24, P <.001, whereas in group 2 this index remained without significant change. Predischarge low-dose dobutamine echocardiography is an accurate tool for prediction of late recovery of myocardial perfusion after acute myocardial infarction treated with thrombolysis.

Risk assessment in patients with acute myocardial infarction treated with thrombolytic therapy.

OBJECTIVE: Several noninvasive methods have prognostic information regarding mortality and new coronary events after an acute myocardial infarction (AMI). The practical for clinical decision-making in the immediate postmyocardial infarction (MI) period is, however, less evident. We investigated consecutive patients with AMI treated with thrombolysis to further clarify this issue. DESIGN: A total of 100 patients (27% women) aged 64 +/- 9 years (mean +/- SD) were studied. Risk assessment based on a clinical score system, myocardial perfusion scintigraphy single photon emission computed tomography (SPECT) at rest and during adenosine stress, echocardiography, radionuclide angiography, symptom-limited exercise stress test, and 24-h Holter ECG recording with ST-analysis and analysis of heart rate variability (HRV) were performed 5-8 days after hospital admission. Mortality, nonfatal reinfarction, and the need for revascularization were followed during 12 months. SETTING: A university hospital. RESULTS: A total of 6 patients died, seven had a nonfatal reinfarction, and 23 were revascularized. Inability to perform an exercise test (P = 0.004) and an ejection fraction (EF) < 40% (P = 0.002) were the only parameters separating those who died from the survivors. No method could predict a nonfatal reinfarction. Patients suffering either death or nonfatal reinfarction had a clinical risk assessment score 2 points higher (8.8 vs. 6.7, P = 0.05) than the group without such events. A positive symptom-limited exercise stress test (P = 0.027), ST-depressions on Holter ECG (P = 0.04), and reversibility on myocardial perfusion scintigraphy (P = 0.029) predicted the need for revascularization. CONCLUSION: Risk assessment based on clinical information, exercise stress testing, and an estimate of left ventricular function (e.g. via echocardiography) contribute with prognostic information in thrombolysed MI-patients. Additional noninvasive investigations such as adenosine-SPECT, analysis of HRV, and Holter-monitoring do not add to these commonly available tools in risk stratification of subjects at low to medium risk.

Factors predicting success rate and recurrence of atrial fibrillation after first electrical cardioversion in patients with persistent atrial fibrillation.

BACKGROUND: The recurrence rate of atrial fibrillation (AF) after elective cardioversion is high. HYPOTHESIS: The study aimed to identify clinical predictors for successful electrical cardioversion and maintenance of sinus rhythm after a first electrical cardioversion in patients with persistent AF without concomitant antiarrhythmic drugs of class I and III. METHODS: Consecutive outpatients (n = 166) with persistent AF for > 1 month, scheduled for elective cardioversion, were prospectively included in the study. A clinical investigation, echocardiographic assay, and Holter electrocardiogram (ECG) before and ECG 4 weeks after cardioversion, were performed in all patients. RESULTS: The mean age of the patients was 68 years (range 45-83) and duration of AF was 5 (1-48) months. Sinus rhythm was established in 124 (75%) patients. In multivariate analysis, only duration of AF < 6 months (p < 0.04, odds ratio [OR] 2.2, 95% confidence interval [CI] 1.1 to 4.7) and patients weight (p < 0.03, OR 2.3, 95% CI 1.1 to 4.8 for weight < 80 kg) were identified as independent predictors of successful cardioversion. At 4 weeks after cardioversion, only 46 (37%) of 124 patients maintained sinus rhythm. Independent factors for maintenance of sinus rhythm, in multivariate analysis, were AF <3 months (p < 0.04, OR 2.5, 95% CI 1.1 to 5.6), treatment with beta blockers (p < 0.00001, OR 7.0, 95% CI 3.0 to 16.3) or verapamil/diltiazem (p < 0.04, OR 3.6, 95% CI 1.1 to 12.1), and right atrial dimension < 37 mm (p < 0.02, OR 5.9, 95% CI 1.4 to 25.4). CONCLUSIONS: In patients with persistent AF, the patient's weight and the duration of AF are independent predictors for a successful cardioversion. Short duration of AF, treatment with beta blockers or verapamil/diltiazem, and right atrial area/dimension are independent predictors for maintenance of sinus rhythm.

Left ventricular function and perfusion in elderly endurance athletes.

PURPOSE: To study the extent to which lifelong physical training can affect cardiovascular capacity, left ventricular function, and myocardial perfusion in elderly men. METHODS AND RESULTS: Ten healthy male veteran endurance athletes aged 73 +/- 3 yr (mean +/- SD) and a control group of 12 sedentary or moderately physically active healthy subjects aged 75 +/- 2 yr were studied. Echocardiographic examinations at rest and exercise stress tests were performed. Gated blood pool scans and myocardial perfusion scintigraphy were recorded at rest and during exercise. Maximal VO2 was 41 +/- 7 mL.kg-1.min-1 in the athletes and 26 +/- 5 mL.kg-1.min-1 in the controls (P < 0.001). Echocardiographic measures of systolic and diastolic function at rest were better in the athletes. The ejection fraction during exercise was also higher in the athletes (P = 0.003). Seven of the 10 athletes, but none of the controls, had pathological myocardial perfusion findings. CONCLUSIONS: By endurance training, a high level of physical capacity can be maintained late in life. The superior cardiovascular function in the veteran athletes, compared with the untrained controls was due to both better systolic and diastolic left ventricular function. Myocardial perfusion defects in athletes should be judged with caution, as this finding is common both in veteran athletes and as previously shown, in young athletes.

Myocardial viability in patients with thrombolyzed myocardial infarction: is it assessable by predischarge exercise electrocardiography test?

BACKGROUND: Most studies concerning exercise electrocardiography (ECG) testing after acute myocardial infarction (AMI) were carried out in the prethrombolytic era. ST-segment elevation in the infarction area during exercise has usually been interpreted as indicating the presence of dyskinesia as a result of extensive left ventricle damage. HYPOTHESIS: This study was undertaken to evaluate the contributions of exercise-induced ST-segment elevation and T-wave pseudonormalization to the assessment of myocardial viability in patients with thrombolyzed myocardial infarction (MI), compared with low-dose dobutamine echocardiography. METHODS: The study comprised 52 consecutive patients with AMI treated with thrombolysis. All patients underwent low-dose dobutamine echocardiography and symptom-limited exercise testing before discharge. RESULTS: Nineteen patients showed ST-segment elevation (Group 1), 9 showed isolated T-wave pseudonormalization (Group 2), and 24 patients did not exhibit either of these ST-T segment changes (Group 3). Low-dose dobutamine echocardiography revealed evidence of viability in 16 patients (84%) in Group I (p = 0.01), 5 (56%) in Group 2 (p = NS), and 11 patients (46%) in Group 3 (p = NS). CONCLUSION: Exercise-induced ST-segment elevation may contribute to the evaluation of myocardial viability in patients with AMI treated with thrombolysis. However, in the absence of exercise-induced ST-segment elevation, further noninvasive studies might be indicated to assess myocardial viability.

Automatic computerized analysis of heart rate variability with digital filtering of ectopic beats.

Analysis of heart rate variability (HRV) has been used in studies of autonomic function and risk assessment in different patient groups such as in patients with diabetes mellitus, after myocardial infarction (MI) and other cardiovascular disease. Ectopic beats can, however, interfere with HRV analysis and give erroneous results. We have therefore studied the impact of ectopic beats on HRV analysis and the ability of a filter algorithm to correct this. Power spectral analysis of synthetic data with an increasing proportion of ectopic beats and 24-h Holter recordings from 98 healthy subjects and 93 post MI patients was done with and without digital filtering and interpolation of errors in the data stream. The analysis of HRV was seriously hampered by less than 1% of ectopic beats. A filter algorithm based on detection and linear interpolation of ectopic beats and other noise in the data stream corrected effectively for this in the synthetic data employed. In the healthy subjects and the post MI patients, filtering markedly reduced the extra variability related to non-normal beats. The software could automatically analyse over one hundred 24-h files in one batch. HRV analysis should include filtering for ectopic beats even with a small number of such beats. It is possible to make a fast analysis automatically even in huge clinical series, which makes it possible to use the method both clinically and in epidemiological studies.

Deterioration in peak systolic velocity is closely related to ischaemia during angioplasty: a vectorcardiographic and tissue Doppler imaging study.

We tested the hypothesis that the extent of signs of ischaemia detected by vectorcardiography (VCG) during elective coronary angioplasty (percutaneous transluminal coronary angioplasty; PTCA) is related to systolic and diastolic myocardial velocities, as determined by tissue Doppler echocardiography. A total of 15 patients undergoing PTCA (12 men/three women; age 61+/-9 years), without prior myocardial infarction and with an ejection fraction of >50%, were included. The balloon inflation was repeated three times, with minimum intervals of 2 min between inflations. Tissue Doppler echocardiography was performed, in an apical two- or four-chamber view, before and at the end of each inflation. Peak systolic velocity, time-to-peak systolic velocity (TTP), peak early (E(m)) and late (A(m)) diastolic velocities, the E(m)/A(m) ratio and isovolumic relaxation time were measured in the basal segments of the left ventricle. VCG recordings were carried out during the whole procedure. ST vector magnitude (ST-VM) and ST change vector magnitude (STC-VM) were monitored. The total duration and area of each VCG change during inflation were calculated for each patient. Isovolumic relaxation time, peak E(m) and A(m) values and the E(m)/A(m) ratio did not change significantly during inflation. Peak systolic velocity decreased (6.7+/-2.0 to 5.3+/-1.9 cm/s; P<0.001) and TTP increased (157+/-60 to 192+/-60 ms; P<0.01) during inflation. Both STC-VM time (r=-0.68, P<0.01) and STC-VM area (r=-0.68, P<0.01) were related to peak systolic velocity during inflation. STC-VM time was also related (r=0.55, P<0.05) to the difference in peak systolic velocity during compared with before inflation. ST-VM was less closely related to peak systolic velocity. Thus the duration and degree of ischaemia, as measured by VCG, are related to peak systolic velocity in the basal segments of the left ventricle.

Asymptomatic versus symptomatic persistent atrial fibrillation: clinical and noninvasive characteristics.

OBJECTIVE: This prospective study was designed to investigate the differences between asymptomatic versus symptomatic arrhythmia as well as left ventricular dysfunction in a consecutive population of patients with persistent atrial fibrillation. DESIGN: A total of 282 consecutive outpatients referred with persistent atrial fibrillation formed the study population. A structured medical history was obtained. A two-dimensional transthoracic echocardiography to assess the left ventricular function and a 24-h electrocardiogram (ECG) recording were performed. Irregularity of the heart rhythm was analysed with heart rate variability (HRV) in the time domain as well as maximum and minimum heart rate and the longest pause. SETTING: Three university hospitals. RESULTS: The mean age of the patients was 69 years and the mean duration of atrial fibrillation was 7 months. The prevalence of symptomatic patients was 68%, while 32% had no symptoms from atrial fibrillation, left ventricular dysfunction was observed in 20%. Asymptomatic subjects had more often lone atrial fibrillation than those with symptoms. Valvular heart disease was an independent predictor of symptoms while male gender, ischaemic heart disease and a high heart rate were independent predictors of impaired left ventricular function. CONCLUSION: Valvular heart disease is related to symptoms in persistent atrial fibrillation. Ischaemic heart disease, male gender and a high heart rate are more common in patients with impaired left ventricular function. Compromised left ventricular function does, occur also in asymptomatic subjects underlining the importance of a careful investigation including echocardiography in all subjects with persistent atrial fibrillation.

Physical training in Syndrome X: physical training counteracts deconditioning and pain in Syndrome X.

OBJECTIVES: The aim of this study was to evaluate the effects of exercise training and body-awareness training in female patients with Syndrome X. BACKGROUND: Patients with Syndrome X, defined as effort-induced angina pectoris, a positive exercise test and a normal coronary angiogram, suffer from a chronic pain disorder. We hypothesized that this disorder results in physical deconditioning with decreased exertional pain threshold. METHODS: Twenty-six patients were randomly assigned to two training groups (A, B) and a control group (C). Group A (n = 8) started, after baseline measurements, with eight weeks of body-awareness training followed by eight weeks of exercise training on a bicycle ergometer three times a week for 30 min at an intensity of 50% of peak work rate. Group B (n = 8) performed only eight weeks of exercise training. Group C (n = 10) acted as controls without any intervention whatsoever. The effects on exercise performance, hormonal secretion, vascular function, adenosine sensitivity and quality of life were evaluated. RESULTS: Body-awareness training did not change the pain response. The two training groups did not differ in effects of exercise training. Exercise capacity before training was below the gender- and age-matched reference range and improved by 34% with training to a level not different from the reference range. Onset of pain was delayed by 100% from 3 +/- 2 to 6 +/- 3 min (p < 0.05) while maximum pain did not change. Thus the pain-response-to-exercise curve was shifted to the right. Syndrome X patients showed a hypersensitivity to low-dose adenosine infusion compared to healthy age- and gender-matched controls (p < 0.0001) that did not change with exercise training. Endothelium-dependent blood flow increase was at baseline within reference range and tended to increase (p < 0.06) following training. In Group A the concentration of cortisol in urine decreased by 53% after body-awareness training (p < 0.05), and this change from baseline remained after physical exercise training (p < 0.05). A similar decrease occurred with only exercise training (Group B). CONCLUSIONS: Physical deconditioning with lower exertional threshold for pain is a prominent feature in Syndrome X. Physical training in Syndrome X results in an increased exercise capacity with lesser anginal pain. We suggest physical training as an effective treatment in Syndrome X.

Autonomic neuropathy--a complication less pronounced in patients with Type 1 diabetes mellitus who have lower blood glucose levels.

AIMS: Autonomic neuropathy is a serious diabetic complication, probably contributing to the death of many young people with Type 1 diabetes mellitus. It is often not diagnosed. METHODS: Patients with Type 1 diabetes from the Stockholm Diabetes Intervention Study were investigated with power spectral analysis (n = 88), heart rate and blood pressure reactions to tilting (n = 66), and heart rate variability during deep breathing (n = 70) a mean of 11.4 years after randomization to intensified conventional treatment (ICT) or standard treatment (ST), the treatment groups similar with regard to age, duration of diabetes and metabolic control at baseline (HbA1c 9.4 (1.3)%, mean (SD)). Blood glucose levels (mean of 29 HbA1c values) during the 10 years were lower in the patients from the ICT group (7.2 (0.6) vs. 8.3 (1.0)%, P = 0.001). RESULTS: Heart rate variability (HRV) in the high frequency range (P = 0.034), the expiration-inspiration ratio (P = 0.020), and the brake index during tilt (P = 0.044) were lower in the ST group, indicating more pronounced parasympathetic insufficiency. Systolic blood pressure fell by 10 (16) mmHg in the ST group, and by 2.5 (15) mmHg in the ICT group 8 min after rising from the supine to a 70 degrees upright position (P = 0.034). A decreased autonomic function was associated with age and higher HbA1c. CONCLUSION: Better autonomic nerve function is associated with lower HbA1c and lower age which were both the same in the intensively and the conventionally treatment groups at baseline. After a mean of 11.4 years autonomic function was better in the intensively treated group.

Beneficial effects of exercise training in heart failure patients with low cardiac output response to exercise - a comparison of two training models.

BACKGROUND: Exercise capacity of patients with chronic heart failure (CHF) correlates poorly with estimates of cardiac function. Yet, it has been suggested that only patients without severely impaired cardiac output (CO) benefit from exercise training. Comparisons of different training models have not been made in the same study. AIMS: To evaluate whether the response to different training models diverges according to the cardiac output response to exercise in patients with chronic heart failure. METHODS: Sixteen CHF patients (63 +/- 11 years) with an ejection fraction of 30 +/- 11% underwent a baseline cardiopulmonary exercise test, right heart catheterization and leg muscle biopsy. Cardiac output (CO) response to exercise was defined as the ratio between CO increase and the increase in oxygen uptake (CO response index) during exercise. Patients were randomized into two training regimens, differing with regard to active muscle mass, i.e. whole body and one-legged exercise. RESULTS: Baseline exercise capacity expressed as W kg-1 correlated with the CO response index (r = 0.51, P < 0.05). Exercise capacity on the cycle ergometer increased in both groups but more in the one-legged than in the two-legged training group (P < 0.05). The improvement in exercise capacity did not correlate with base-line exercise capacity. It correlated with CO response index in the one-legged (r = 0.75, P < 0.01) but not in the two-legged training group. CO response index correlated negatively with the pulmonary capillary wedge pressure at peak exercise (r = - 0.60, P < 0.05). The increase in leg muscle citrate synthase activity after training correlated negatively with the baseline CO response index (r = - 0. 50, P < 0.05). CONCLUSIONS: The improvement of exercise capacity after one-legged training correlates with the CO increase in relation to the O2 uptake before training. In patients with low CO response, individualization of the exercise regimen is needed and the benefits of training a limited muscle mass at a time deserve further study.