Mechanical deformation in adult patients with unrepaired aortic coarctation

Aortic coarctation is a congenital heart disease that causes an increased left ventricular afterload, resulting in increased systolic parietal tension, compensatory hypertrophy, and left ventricular systolic and diastolic dysfunction. The speckle tracking is a new echocardiographic technique that allows the detection of subclinic left ventricular systolic dysfunction. The aim of this study was to detect early left ventricular dysfunction using mechanical deformation by echocardiography in adults with un-repaired aortic coarctation. A total of 41 subjects were studied, 20 patients with aortic coarctation and 21 control subjects, 21 women (51.2%), with an average age of 30?±?10 years. All patients with aortic coarctation had systemic arterial hypertension (p?<?0.001). Seventy percent (14/20) of the patients had bicuspid aortic valve. Statistically significance (p?<?0.005) were found in left ventricular mass index, E/e ratio, pulmonary artery systolic pressure and peak velocity and maximum gradient of the aortic valve. The global longitudinal deformation of the left ventricle in patients with aortic coarctation was significative decreased, p?<?0.001. The ejection fraction and the global longitudinal deformation of the left ventricle were significantly lower in patients with aortic coarctation compared to the control group, p?<?0.003, p?<?0.001, respectively. The subgroup of patients with coarctation and left ventricular ejection fraction?<?55% had a marked decrease in global longitudinal strain (??15.9?±?4%). The radial deformation was increased in patients with aortic coarctation and showed a trend to be significant (r?=?0.421; p?<?0.06). A significant negative correlation was observed between the global longitudinal deformation and left ventricular mass index (r?=?0.54; p?=?0.01) in the aortic coarctation group. The patients with aortic coarctation and left ventricular hypertrophy had marked reduction of left ventricular global longitudinal deformation (??16%, p?<?0.05). In our study patients with normal left ventricular ejection fraction had abnormal global longitudinal deformation and also the increased left ventricular mass was related with a decreased left ventricular global longitudinal deformation as a sign of subclinical systolic dysfunction.     

Effect of pacing-induced ventricular dyssynchrony on right ventricular function

Background: Asynchronous electrical activation induced by right ventricular (RV) pacing can cause several abnormalities in left ventricular (LV) function. However, the effect of ventricular pacing on RV function has not been well established. We evaluated RV function in patients undergoing long‐term RV pacing. Methods: Eighty‐five patients and 24 healthy controls were included. After pacemaker implantation, conventional echocardiography and strain imaging were used to analyze RV function. Strain imaging measurements included peak systolic strain and strain rate. LV function and ventricular dyssynchrony by tissue Doppler imaging (TDI) were assessed. Intra‐ and interobserver variabilities of TDI parameters were tested on 15 randomly selected cases. Results: All patients were in New York Heart Association functional class I or II and percentage of ventricular pacing was 96 ± 4%. RV apical induced interventricular dyssynchrony in 49 patients (60%). LV dyssynchrony was found in 51 patients (60%), when the parameter examined was the standard deviation of the time to peak myocardial systolic velocity of all 12 segments greater than 34 ms. Likewise, septal‐to‐lateral delay ≥65 ms was found in 31 patients (36%). All echocardiographic indexes of RV function were similar between patients and controls (strain: ?22.8 ± 5.8% vs ?22.1 ± 5.6%, P = 0.630; strain rate: ?1.47 ± 0.91 s^?1 vs ?1.42 ± 0.39 s^?1, P = 0.702). Intra‐ and interobserver variability for RV strain was 3.1% and 5.3%, and strain rate was 1.3% and 2.1%, respectively. Conclusions: In patients with standard pacing indications, RV apical pacing did not seem to affect RV systolic function, despite induction of electromechanical dyssynchrony. (PACE 2011; 34:155–162)     

Assessment of left ventricular diastolic function in children after successful repair of aortic coarctation

The purpose of the study was an assessment of left ventricular diastolic function in children after the successful repair of aortic coarctation (CoA). The prospective study concerned 32 pediatric patients after the CoA surgery. Tissue Doppler imaging parameters including strain and strain rate and the conventional echocardiographic indexes were analyzed in patients and healthy controls. Analysis of mitral annulus velocities, E?CE?? ratio, strain, and strain rate of left ventricular mid-cavity segments and conventional indexes of mitral inflow showed the worsening of left ventricular diastolic mechanics in the study group compared to healthy controls. The E/E?? ratio was significantly higher in the study group compared to the control group (8.30?±?3.24 vs. 6.95?±?1.36; p?<?0.05). The early diastolic strain rate to late diastolic strain rate ratio as well as early to late diastolic strain ratio of the left ventricular mid-cavity segments were significantly lower in the study group compared to healthy controls (1.81?±?0.63 vs. 3.74?±?1.53; p?<?0.001 and 1.20?±?0.49 vs. 3.41?±?1.26; p?<?0.001). No differences of the pulmonary venous flow parameters between those two groups were observed. The left ventricular diastolic mechanics in hypertensive patients after CoA repair did not differ from normotensive subjects. Hypertensive and normotensive children after surgical repair of CoA are found to have worsening of the left ventricular diastolic mechanics suggesting the impairment of the active myocardial relaxation.     

Evidence of diminished coronary flow in pulmonary hypertension ‐ explaining angina pectoris in this patient group?

Background: Many patients with pulmonary hypertension (PH) have symptoms of angina without evidence of occlusive coronary artery disease. For the first time, this study addresses the influence of progressively increasing pulmonary artery pressure (PAP) on left anterior descending artery flow in a rat model of PH. The role of pulmonary artery dilatation, septal wall motion abnormality, cardiac output or diastolic blood pressure in determining coronary blood flow (CBF) during PH was determined. Methods: Pulmonary hypertension was induced in 6‐week‐old female nude rats (n = 44) using monocrotaline. Animals underwent right heart catheterization and echocardiography, and blood pressure measurement was taken at baseline, 21 and 35 days. Results: A total of 103 echocardiographic studies were carried out at three fixed time points in rats with variable PAP. CBF decreased from 46·6 ± 14·3 to 24·7 ± 12·3 cm s^?1 (P<0·001) over time. Pulmonary artery diameter increased from 2·30 ± 0·19 to 2·83 ± 0·30 mm (P<0·001), and left ventricular (LV) cardiac output decreased from 143 ± 23 to 78 ± 30 ml min^?1 (P<0·001). Using observed solution estimates of 0·00170 (P = 0·0005) and ?1·75 (P = 0·006) for these variables, we calculated that CBF increased by 5·90 cm s^?1 (15·6%, CI: 14·5–17·1%) or decreased by ?4·86 cm s^?1 (?12·9%, CI: ?14·1–11·9%) for every standard deviation increase in LV cardiac output or pulmonary artery diameter, respectively. CBF decreased significantly with increasing PAP. Pulmonary artery diameter and LV cardiac output appear to be independent determinants of coronary flow in PH. Conclusions: Coronary flow reduction in murine PH has potential to be clinically meaningful and should therefore further studied in a clinical trial.     

Changes in cardiac function and structure in newly diagnosed Graves’ disease. A conventional and 2D-speckle tracking echocardiography study

Overproduction of thyroid hormones leads to structural as well as functional cardiac changes. Conventional echocardiography but also recently developed sophisticated two-dimensional echocardiography speckle (2D-STE) tracking allow elaborate evaluation of these changes. Our purpose was to investigate the effects of thyroid hormones overproduction on the heart in patients with Graves’ disease and changes that occur after 6 months thyrostatic therapy. We conducted a prospective, case-control study of 6 months duration. Full echocardiographic assessment at diagnosis and after 6 months of thyrostatic therapy were performed in 44 patients with Graves’ disease, aged 37.6?±?9.1 years. Additionally, 43 euthyroid controls were studied for the same time period. Left ventricular end diastolic diameter (LVEDD) and left ventricular end systolic diameter (LVESD) were higher in the patient group while triscupid annular plane systolic excursion (TAPSE) was lower in the patient group. Moreover, left ventricular (LV) mass index and left atrium (LA) volume index were higher in the Graves’ disease group. Diastolic impairment as assessed with conventional echocardiography including tissue Doppler was present in the patient group (E/A ratio 0.87?±?0.10,). 2D-STE analysis, revealed an increase in the strain rate at the isovolumic relaxation time (SRIVRT, 0.310?±?0.07 patients versus 0.298?±?0.09 s^?1 controls). Improvement in diastolic and right systolic function as well as in left ventricular structural parameters was observed after restoration of euthyroidism (E/A ratio from 0.87?±?0.10 versus 0.9?±?0.08, p?<?0.05). Patients with newly diagnosed Graves’ showed an improvement in diastolic function, right systolic function and structural parameters after 6 months of thyrostatic treatment.     

Reduced cerebral oxygen–carbohydrate index during endotracheal intubation in vascular surgical patients

Brain activation reduces balance between cerebral consumption of oxygen versus carbohydrate as expressed by the so‐called cerebral oxygen‐carbohydrate‐index (OCI). We evaluated whether preparation for surgery, anaesthesia including tracheal intubation and surgery affect OCI. In patients undergoing aortic surgery, arterial to internal jugular venous (a‐v) concentration differences for oxygen versus lactate and glucose were determined from before anaesthesia to when the patient left the recovery room. Intravenous anaesthesia was supplemented with thoracic epidural anaesthesia for open aortic surgery (n = 5) and infiltration with bupivacaine for endovascular procedures (n = 14). The a‐v difference for O₂ decreased throughout anaesthesia and in the recovery room (1·6 ± 1·9 versus 3·2 ± 0·8 mmol l^?1, mean ± SD), and while a‐v glucose decreased during surgery and into the recovery (0·4 ± 0·2 versus 0·7 ± 0·2 mmol l^?1, P<0·05), a‐v lactate did not change significantly (0·03 ± 0·16 versus ?0·03 ± 0·09 mmol l^?1). Thus, OCI decreased from 5·2 ± 1·8 before induction of anaesthesia to 3·2 ± 1·0 following tracheal intubation (P<0·05) because of the decrease in a‐v O₂ with a recovery for OCI to 4·6 ± 1·4 during surgery and to 5·6 ± 1·7 in the recovery room. In conclusion, preparation for surgery and tracheal intubation decrease OCI that recovers during surgery under the influence of sensory blockade.     

Is arterial stiffening in Alström syndrome linked to the development of cardiomyopathy?

Background Alström syndrome (AS) is a rare autosomal recessive condition characterized by retinal degeneration, childhood obesity, and severe insulin resistance. Dilated cardiomyopathy of unknown aetiology is a well‐recognized and potentially lethal complication. The aim of this study was to investigate the relationship between vascular function, hyperinsulinaemia and cardiac performance in AS. Materials and methods Fifteen subjects with AS (mean age 21 years, range 10–35) were studied and compared with age‐, sex‐, and blood pressure‐matched healthy controls. Large artery stiffness and wave reflections were assessed in both groups by measuring aortic and brachial pulse wave velocity (PWV) (carotid‐femoral and carotid‐radial) and augmentation index (AIX) (Sphygmocor). In AS subjects, left ventricular function was assessed by echocardiography and metabolic parameters including fasting insulin, glucose, lipids and brain natriuretic peptide were also measured. Results Comparing AS subjects vs. controls (mean ± SD), AIX was elevated in AS subjects (18 ± 9% vs. 3 ± 11%, P < 0·0001). No significant changes in brachial PWV (8·1 ± 1·3 m s⁻¹ vs. 7·3 ± 1·1 m s⁻¹, P = 0·14) or aortic PWV (6·5 ± 1·1 m s⁻¹ vs. 6·0 ± 1·0 m s⁻¹, P = 0·26) were observed. AS subjects were hyperinsulinaemic and had disturbances in lipid profiles relative to controls. No correlations were observed between vascular, metabolic and echocardiographic parameters. Conclusions In AS there are alterations in the shape of the central arterial pressure waveform associated with augmented aortic systolic pressure and indicative of increased wave reflection. Unfavourable central arterial haemodynamics in AS may contribute to the development of cardiomyopathy but other aetiological factors are probably involved.     

Myocardial velocities measured during adenosine, dobutamine and supine bicycle exercise: a tissue Doppler study in healthy volunteers

Background: Dobutamine stress echocardiography (DSE) quantified by tissue Doppler (TVI) have improved the diagnostic capacity of the procedure. Quantification of other stress modalities, e.g. adenosine stress echo (ASE) and exercise stress echocardiography (ESE) are necessary for assessing any pathophysiological differences in different forms of stress. Methods: Ten healthy individuals underwent ASE, DSE, and ESE during a span of 2–5 days. Left ventricular (LV) apical images at rest and peak stress (max) were postprocessed using TVI on a GE System FiVe equipment. ECG‐derived QRS duration (QRSD, ms), heart rate (HR, bpm), TVI‐estimated basal systolic velocities (S2V, cm s^?1), ejection time (S2T, ms) and strain (S, %) were computed off‐line and compared. Longitudinal displacement imaging, tissue tracking, was also made. Results: Data for ASE, DSE and ESE during peak stress were (HR: 84 ± 12***, 142 ± 19, 137 ± 27; P<0·001) (QRSD: 92 ± 18**, 74 ± 13, 79 ± 9; P<0·05), (S2T: 307 ± 34***, 175 ± 53, 192 ± 25; P<0·001) and (S%: 26·0 ± 3·0, 21·2 ± 7·3, 22·1 ± 5·1; P = n.s.) respectively. Velocity response, registered in the LV septum at max, was lowest during ASE (7·4 ± 1·4) highest during DSE (13·0 ± 2·7; P<0·001 versus ASE) and somewhat intermediate during ESE (11·3 ± 3·5; P<0·001 versus ASE). In contrast, strain and displacement did not differ. Conclusion: ASE evokes significantly less LV systolic response compared with both DSE and ESE. Increased velocity (P<0·05 versus rest) and strain (P>0·05) response at a much lower HR indicates that adenosine has minor effects on contraction presumably secondary to vasodilatation. Powerful chronotropic response to DSE and ESE is probably prerequisite for strong velocity response at the expense of strain and displacement. TVI‐assisted stress echocardiography thereby shows different LV systolic response in healthy individuals, depending on stress modality.     

Cardiac sympathetic activity is associated with inflammation and neurohumoral activation in patients with idiopathic dilated cardiomyopathy

Background: Idiopathic dilated cardiomyopathy (IDC) is characterized by sympathetic nervous overactivity, inflammation and neurohumoral activation; however, their interrelationships are poorly understood. Methods and results: We studied 99 patients with IDC (age 54 ± 1 years, left ventricular ejection fraction (EF) 40 ± 1%, maximum oxygen uptake (VO₂max) 20 ± 1 ml kg^?1 min^?2, mean ± SEM) by using ¹²³I‐metaiodobenzylguanidine (MIBG) imaging. MIBG washout and MIBG heart/mediastinum (H/M)‐ratio at 4 h postinjection were calculated. In addition, the plasma levels of interleukin (IL)‐6 and N‐terminal B‐type natriuretic peptide (NT‐proBNP) were measured. MIBG washout and MIBG H/M ratio had a significant correlation with IL‐6 (r = 0·42, P<0·001 and r = ?0·31, P<0·01) and NT‐proBNP (r = 0·48, P<0·001 and r = ?0·40, P<0·001). During a median follow‐up of 4·1 years, 20 patients (20%) had an adverse cardiac event (death, heart transplantation or application of biventricular pacemaker or implantable cardioverter–defibrillator). In these patients, MIBG washout was higher (53 ± 4 versus 40 ± 2%, P = 0·01) and H/M ratio lower (1·38 ± 0·04 versus 1·51 ± 0·02, P = 0·01) than in patients without an event. Conclusions: In dilated cardiomyopathy, myocardial sympathetic innervation and activity are related to inflammation and neurohumoral activation. These relationships are at least partly independent of left ventricular function and exercise capacity.     

Effect of non-hypotensive haemorrhage on plasma catecholamine levels and cardiovascular variability in man

Background: It is well known from animal research that non‐hypotensive haemorrhage produces sympathoexcitatory responses assessable by both the rise in plasma catecholamine levels and the shift of autonomic influences on the heart to more sympathetic and less parasympathetic control. Data in humans are restricted. Methods: Heart rate variability (HRV), systolic blood pressure (FINAPRES) variability (BPV), and catecholamine plasma levels were measured before and after haemorrhage in 30 healthy blood donors and compared with those from 10 control subjects without blood loss. Spectral power of HRV and BPV in very low (0·02–0·06 Hz), low (0·07–0·14 Hz), and high (0·15–0·40 Hz) frequency bands were calculated by Fourier analysis. Catecholamine plasma levels were assayed by dual column reverse‐phased high‐performance liquid chromatography (HPLC). Results: Haemorrhage of 5·6 ± 1·2 ml kg^?1 body weight increased plasma norepinephrine levels (215 ± 92 pg ml^?1 versus 254 ± 95 pg ml^?1; P = 0·002), increased BPV in the low frequency band (Mayer waves; 1·8 ± 1·0 ln [mmHg²] versus 2·0 ± 0·9 ln [mmHg²]; P = 0·021), and decreased the vagally transmitted high frequency HRV (6·9 ± 1·1 ln [MI²] versus 6·5±1·2 ln [MI²]; P<0·0001), but did not induce significant changes in heart rate (66 ± 11 bpm versus 67 ± 11 bpm; P = 0·79) and arterial blood pressure (mean values: 84 ± 13 mmHg versus 87 ± 13 mmHg; P = 0·12). Conclusions: As suggested by plasma norepinephrine levels, systolic BPV and HRV, non‐hypotensive haemorrhage produces sympathoexcitatory responses as well as vagal withdrawal of heart rate control in humans.     

Regional Left Ventricular Myocardial Shortening in Normotensive Patients Late after Aortic Coarctation Repair - Normal or Impaired?

Despite successful repair of aortic coarctation (AoC), changes in the left ventricular (LV) regional myocardial function are reported. The aims of this study were (i) to determine LV regional longitudinal deformation in patients who underwent a repair of AoC, who were normotensive and who had normal LV global function; and (ii) to establish a potential correlation between the degree of residual narrowing in the descending aorta and the extent of LV regional deformation. We studied 22 normotensive patients aged 19–58 y (mean 32.6; SD±11.3). Maximal strain, ε (%), as well as peak systolic and early and late diastolic strain rates (SRs; s⁻¹), were obtained on the basis of speckle tracking. The data were compared with those obtained from sex and age-matched controls. Regional SRs were significantly reduced for the LV anterior wall during systole and early diastole –1.1 vs. –1.39; 1.41 vs. 1.86 s⁻¹, respectively; p<0.05. Transaortic maximal and mean gradients across the coarctation site correlated with ε and systolic SR obtained from the midsegment of the LV anterior wall. Despite a successful repair, absence of systemic hypertension and normal global LV function, regional deformation properties of the anterior LV wall were impaired. The degree of longitudinal impairment in this anatomical region correlated with the extent of residual narrowing. (E-mail: miroslaw.kowalski@ikard.pl)     

Influence of body size and age on maximal systolic velocity of mitral annulus motion

The maximal systolic velocity of the mitral annulus motion (or maximal systolic long‐axis contraction velocity of the ventricle, MLACV) has been suggested as a means to assess left ventricular function. However, reference values for a wide range of age and body size are lacking. The maximal systolic velocity was studied with M‐mode echocardiography using the apical four‐ and two‐chamber views. Data are reported as the average of the measurements of four sites of the mitral annulus. Fifty‐seven healthy subjects aged 6 months to 72 years were studied. In children and adolescents up to age 18, MLACV had a significant positive correlation with age, height, body surface area, weight and mitral annulus motion amplitude and a significant negative correlation with heart rate. In adults, there was a significant positive correlation between MLACV and height, mitral annulus motion amplitude and body surface area and a significant negative correlation with age and heart rate. Multiple stepwise analysis showed that the maximal systolic velocity is highly dependent on height and age in children and adolescents up to age 18, and on height in adults. The maximal long‐axis contraction velocity (MLACV) can be described by the following equations: MLACV (mm s^–1) = 24·0 + 0·34 × height (cm) (Standard Error of the Estimate (SEE)=10·5) in children and adolescents, and MLACV (mm s^–1) = –50·5 + 0·75 × height (cm) (SEE=9·8) in adults over 18. There were significant differences between the four sites, with the highest velocity at the lateral site and the lowest velocity at the septal site. No significant difference was found between inspiratory and expiratory beats.     

A reproducible and stable model of acute ischaemic left ventricular failure in dogs

Summary. A model of acute ischaemic left ventricular (LV) failure is presented. In closed-chest anaesthetized dogs 50 μm plastic microspheres were injected repeatedly into the left main coronary artery over a period of about 40 min. The injections effected stepwise elevations of LV end-diastolic pressure (Lvedp ). Thus, Lvedp could be increased to a desired level, about 20 mmHg, in a very controlled manner. All dogs developed signs of markedly depressed LV performance. Haemodynamic conditions stabilized about 60 min after embolization, and then remained essentially stable for at least 75 min. Lvedp increased from 5·7 ± 0·6 before to 26·1 ± 0·8 mmHg (mean ± SEM) 60 min after embolization. The maximum LVdP/dt decreased from 2696 ± 169 to 1823 ± 98 mmHg·s^-1, cardiac output decreased from 2·81 ± 0·20 to 1·98 ± 0·14 1·min^-1 and mean aortic blood pressure decreased from 144±4 to 127±3 mmHg, while total peripheral resistance increased from 56±3 to 69±3 mmHg·l^-1·min. Myocardial blood flow decreased from 103±7 to 79 ±6 ml·min^-1·100 g^-1 and myocardial oxygen consumption decreased from 12·5±0·9 to 8·3·0·8 ml· min^-1·100 g^-1. Myocardial uptake of lactate and free fatty acids decreased markedly. Electrocardiography showed signs of acute ischaemia. There were no deaths due to ventricular fibrillation. Morphological studies showed multiple small infarcts throughout the entire LV. In conclusion, repeated coronary embolization with 50 μm plastic microspheres, guided by the rise of Lvedp represents a simple and reproducible method for induction of uniform and stable acute LV failure.     

Comprehensive echocardiographic assessment of biventricular function in the rabbit,animal model in cardiovascular research: feasibility and normal values

Quantification of cardiac structure and function is central in cardiovascular research. Rabbits are valuable research models of cardiovascular human disease; however, there is little normal data available. The aim of this study was to investigate feasibility and provide normal values for comprehensive echocardiographic assessment of biventricular function in rabbits. New Zealand white rabbits underwent trans-thoracic echocardiography using a general electric (GE) Vivid 7/E9 system with a 10 MHz transducer, under light sedation, to evaluate biventricular function and dimensions. Images for two-dimensional, M-mode, tissue Doppler imaging (TDI) and speckle-tracking strain echocardiography were acquired and analysed. 55 male rabbits (sized matched with a newborn human baby) were studied, mean weight was 2.9?±?0.23 kg. Adequate images were obtained in 90% for the left ventricle (LV) and 80% for the right ventricle (RV). Two-dimensional speckle-tracking strain was feasible in 60%. Average heart rate was 248?±?36 beats per minute; LV ejection faction 72?±?8.0; RV fractional area change 45.9?±?9.0%; RV myocardial performance index 0.39?±?0.35; tricuspid annular planar systolic excursion 0.60?±?0.24 cm. LV TDI parameters were S’ 8.6?±?3.1 cm/s; E’ 12.0?±?4.46 cm/s. RV TDI parameters were S’ 10.49?±?3.18; E’ 14.95?±?4.64 cm/s. LV and RV global peak systolic longitudinal strain were ?17?±?5 and ?22?±?8%, respectively. Comprehensive investigation of biventricular dimensions and function by echocardiography is feasible in the rabbit. Apical views and strain imaging have lower feasibility. Normal values of LV and RV functional parameters are with comparable values to human children. Animal cardiovascular research is key to develop new goals in clinical practice.     

Cholinergic blockade and the mesenteric artery response to head-up tilt-induced central hypovolaemia

The influence of muscarinic blockade on the superior mesenteric artery (SMA) response to head-up tilt (HUT) was assessed by Doppler ultrasound in eight healthy adults pretreated with i.v. glycopyrron. During supine rest, cholinergic blockade increased heart rate from 58 ± 3 to 106 ± 6 beats min^?1 (mean ± SE) and mean arterial pressure from 81 ± 3 to 97 ± 4 mmHg (P<0·01) and it reduced the cardiac stroke volume from 89 ± 6 to 59 ± 7 ml (P<0·01) with no significant effect on the SMA diameter and blood flow velocities. HUT provoked a further increase in heart rate to 134 ± 5 beats min^?1(P<0·01) and a reduction in stroke volume to 45 ± 4 ml (P<0·01). The early diastolic velocity increased from ?51 ± 4 to 6 ± 8 cm s^?1 during the normotensive stage of HUT and further to 21 ± 9 cm s^?1 during the hypotensive stage with a reduction in mean arterial pressure from 97 ± 4 to 73 ± 7 mmHg (P<0·01) but, in contrast to control HUT (without cholinergic blockade), the end-diastolic velocity did not change significantly. Maintenance of blood velocity and diameter in spite of an increase in arterial pressure at rest indicates increased SMA impedance. Likewise, during hypovolaemia, a glycopyrron-induced inhibition in diastolic velocity supports an increase in SMA impedance. The results indicate cholinergic vasorelaxing influence on the superior mesenteric artery both at rest and during normotensive central hypovolaemia.     

The effect of different treatment strategies on left ventricular myocardial deformation parameters in patients with chronic renal failure

The aim of this study was to compare left ventricular (LV) functions by speckle tracking echocardiography (STE) in chronic kidney disease (CKD) patients in various stages and under different renal replacement treatments in order to evaluate possible differences between them. This prospective study included 150 patients with CKD. Renal transplantation patients with glomerular filtration rate greater than 60 ml/min/1.73 m², patients receiving hemodialysis three times a week, and patients in the predialysis stage with glomerular filtration rate less than 30 ml/dk/1.73 m² were assigned into Group 1 (n?=?50), Group 2 (n?=?50), and Group 3 (n?=?50), respectively. LV longitudinal, circumferential, and radial myocardial deformation parameters (strain, strain rate [SR], rotation, twist) were evaluated by STE. Peak systolic longitudinal strain was higher in the transplantation group than the hemodialysis group (??19.93?±?3.50 vs???17.47?±?3.28%, p?<?0.017). Peak systolic circumferential strain was lower in the hemodialysis group (??20.97?±?4.90%) than Groups 1 and 3 (??25.87?±?4.20 and ??24.74?±?4.55%, respectively, p?<?0.001). Peak systolic radial SR was higher in the transplantation group than the hemodialysis group (1.84?±?0.52 vs 1.55?±?0.52 s^?1, respectively, p?<?0.017). Other longitudinal and circumferential deformation parameters together with peak early diastolic radial SR and twist were also significantly different between the groups. Strain, SR, and twist values were mostly lower in the hemodialysis patients, but generally higher in the transplantation patients. LV functions evaluated by STE are better in the renal transplantation patients than the hemodialysis patients and than those in the predialysis stage. This may indicate beneficial effects of renal transplantation on cardiac functions.     

Arterial stiffening and cardiac hypertrophy in a new rat model of type 2 diabetes

Background We determined the effects of NIDDM on haemodynamic parameters describing arterial wall elasticity and cardiac hypertrophy in rats administered streptozotocin (STZ) and nicotinamide (NA), using the aortic impedance analysis. Methods Male Wistar rats at 2 months were administered intraperitoneally 180 mg kg⁻¹ of NA, 30 min before an intravenous injection of 50 mg kg⁻¹ STZ, to induce type 2 diabetes. The STZ‐NA rats were divided into two groups, 4 weeks and 8 weeks after induction of diabetes, and compared with untreated age‐matched controls. Pulsatile aortic pressure and flow signals were measured by a high‐fidelity pressure sensor and electromagnetic flow probe, respectively, and were then subjected to Fourier transformation for the analysis of aortic input impedance. Results In each diabetic group, the experimental syndrome was characterized by a moderate and stable hyperglycaemia and a relative deficiency of insulin secretion. However, the 8‐week but not the 4‐week STZ‐NA diabetic rats showed a decrease in cardiac output in the absence of any significant changes in mean aortic pressure, having increased total peripheral resistance. The diabetic syndrome at 8 weeks also contributed to an increase in aortic characteristic impedance, from 1·49 ± 0·33 (mean ± SD) to 1·95 ± 0·28 mmHg s mL⁻¹ (P < 0·05), suggesting a detriment to the aortic distensibility in NIDDM. Meanwhile, the STZ‐NA diabetic animals after 8 weeks had an increased wave reflection factor (0·46 ± 0·09 vs. 0·61 ± 0·13, P < 0·05) and decreased wave transit time (25·8 ± 3·8 vs. 20·6 ± 2·8 ms, P < 0·05). Ratio of the left ventricular weight to body weight was also enhanced in the 8‐week STZ‐NA diabetic rats. Conclusion The heavy intensity with early return of the pulse wave reflection may augment systolic load of the left ventricle coupled to the arterial system, leading to cardiac hypertrophy in the rats at 8 weeks after following STZ and NA administration.     

Obese children show increased intimal wall thickness and decreased pulse wave velocity

Objective: Childhood obesity confers an increased risk of vascular changes and adult cardiovascular disease. Using a high‐resolution ultrasound technique that enables separation of intimal and medial layers, we examined the intimal thickness (IT) and intimal–medial thickness (IMT) of radial (RA) and dorsal pedal (DPA) arteries and the pulse wave velocity (PWV) in overweight/obese children and adolescents and in healthy subjects. Methods and results: IT and IMT of RA and DPA and PWV were measured in 33 obese children and adolescents (13·9 ± 1·6 years) and in 18 matched lean controls (14·3 ± 2·2). Increased RA IT was found in the obese group, whereas no differences in RA IMT or medial thickness were observed. Obese females accounted for the entire difference in RA IT (P = 0·04). DPA IT was inversely correlated with HDL cholesterol in the obese group (?0·56, P = 0·0089). PWV was lower in the obese group than in the lean group (6·2 ± 0·8 versus 7·0 ± 0·9 m s^?1, respectively; P = 0·001). Conclusions: Obese children and adolescents, primarily females, present with increased RA IT. The decreased PWV in the obese versus lean subjects might reflect general vasodilatation.     

定量分析主动脉瓣和二尖瓣关闭不全的心肌收缩期力学参数

本文根据弹性力学原理使用超声心动图仪配合录像机、微机测量主动脉瓣关闭不全和二尖瓣关闭不全各１０例和５０例正常人瞬时左室收缩期室壁应力（每单位面积的力）一应变（每单位长度的变化）关系。结果表明：国人主动脉瓣关闭不全者左室收缩期最大心肌弹性劲度（ｍａｘＥａｖ）由正常人１１２．８±２３．５增至１３８．８±４７．３４ｋＰａ，零应力壁间小轴径（Ｄｏｍ）由正常３．９±０．５２ｃｍ增至６．０２±１．０１ｃｍ；二尖瓣关闭不全者ｍａｘＥａｖ由正常值增加至１５０．０４±３２．４５ｋＰａ，Ｄｏｍ由正常值增至５．０４±０．５４ｃｍ。ｍａｘＥａｖ和Ｄｏｍ是评估心肌收缩性变化的理想指标。本文对主动脉瓣和二尖瓣关闭不全的心肌收缩力进行了定量分析。     

Simultaneous quantification of myocardial perfusion,oxidative metabolism,cardiac efficiency and pump function at rest and during supine bicycle exercise using 1‐11C‐acetate PET – a pilot study

Background: PET using 1‐¹¹C‐acetate (ACE‐PET) applied at rest is used for measuring absolute myocardial blood flow (MBF) and oxidative metabolic rate (k_mono). We evaluated the feasibility of quantitative ACE‐PET during exercise. Methods: Five endurance athletes underwent dynamic PET scanning at rest and during supine bicycle stress. Exercise was maintained at a workload of 120 Watt for 17 min. The rate‐pressure product (RPP) was recorded repeatedly. MBF, k_mono in left (LV) and right (RV) ventricular wall, cardiac output (CO), cardiac efficiency and a lung uptake value reflecting left heart diastolic pressures were calculated from the PET data using previously validated models. Results: MBF increased from 0·71 ± 0·17 to 2·48 ± 0·25 ml min^?1 per ml, LV‐k_mono from 0·050 ± 0·005 to 0·146 ± 0·021 min^?1, RV‐k_mono from 0·023 + 0·006 to 0·087 + 0·014 min^‐1, RPP from 4·7 ± 0·8 to 13·2 ± 1·4 mmHg × min^?1 × 10³ and Cardiac Output from 5·2 ± 1·1 to 12·3 ± 1·2 l min ^?1 (all P < 0·001). Cardiac efficiency was unchanged (P = 0·99). Lung uptake decreased from 1·1 ± 0·2 to 0·6 ± 0·1 ml g^?1 (P < 0·001). Discussion: A number of important parameters related to cardiac function can be quantified non‐invasively and simultaneously with a short scanning protocol during steady state supine bicycling. This might open up new opportunities for studies of the integrated cardiac physiology in health and early asymptomatic disease.