Supine Bicycle Exercise Test Research Articles

Haemodynamic indicators of arteriolar dysregulation during combined hyperventilation and exercise test in patients with ANOCA (SESPASM)

Abstract Introduction In patients with angina and non-obstructed coronary arteries (ANOCA), functional dysregulation such as epicardial coronary spasm and microvascular dysfunction (microvascular spasm and /or impaired microvascular dilatation) frequently coexist. The aim was to analyse haemodynamic indicators of arteriolar dysregulation during combined hyperventilation and exercise stress echo test in patients with ANOCA. Methods In a prospective study we enrolled 38 patients (56±13 years, 31 females) with ANOCA, proven by normal coronary angiogram. Stress echocardiography protocol with Doppler measurements of coronary flow consisted of hyperventilation test for spasm provocation (HYP, respiratory rate of 30 per min for 5') followed by supine bicycle exercise test (HYP+EXE) for assessment of endothelium dependent function. Adenosine test was done (ADO 140 mcg/kg in 1 min) for estimation of endothelium independent vasodilatation. Coronary flow velocity (CFV) was assessed in distal LAD by Transthoracic Doppler echocardiography at the end of the each stage of the test. Abnormal response to HYP was a CFV ratio (stress/rest) <1.0 (vasoconstrictor response). CFV ratio at peak HYP+ EXE was an indicator of endothelial dependent vasodilatation (<2 blunted response). An abnormal response to ADO was a CFV reserve <2.0 (blunted vasodilatory response). Results The double product increased during HYP in comparison to rest (13263 vs 10321, p<0.001), and further increased with EXE (23817 vs HYP, p<0.001). Chest pain was present in 6 pts during HYP, and in additional three pts during HYP+EXE (15.8% vs 23.7%, p=0.25). ST segment depression was present in 6 pts during HYP and 23 during HYP+EXE (15.79% vs 60.52%, p<0.001). Wall motion abnormality was provoked with HYP in three pts (7.89%) and in ten (26.3%) with HYP+EXE (p=0.016). CFV ratio was abnormal for vasoconstriction during HYP in 16 (42.1%) and blunted in 23 (60.52%) pts during HYP+EXE (Fig 1). Vasodilation during ADO was preserved in all patients, but one. There was significant difference between CFV reserve during HYP+EXE vs ADO (1.98±0.49 vs 2.53±0.43 respectively, p<0.001) (Fig. 2). Conclusion Our results indicate that HYP induce microvascular dysfunction with vasospastic component which is reflected in reduced CFV ratio. This prevents the normal hyperemic response during EXE in more than a half of patients. Endothelial independent vasodilatation during ADO hyperemia was perserved in all patients, excluding structural microvasculature remodeling. HYP+EXE provocation with noninvasive measurement of coronary flow is a promising test for assessing mechanism of arteriolar dysregulation in ANOCA patients. Funding Acknowledgement Type of funding sources: None.

156 Shear wave propagation velocity after aortic valve closure could be a novel parameter for myocardial contractility

Abstract Funding Acknowledgements Research Foundation (FWO) Flanders grant Background Shear wave imaging is a novel ultrasound technique based on the detection of transverse waves travelling through the myocardium by using high frame rate (HFR) echocardiography. These waves can be induced by an external or internal stimulus, such as aortic valve closure (AVC). The propagation velocity of shear waves is directly dependent on myocardial stiffness. It has been previously suggested in animals that the shear wave propagation velocity at AVC might be related to myocardial contractility. Aim The aim of this study was to validate if the shear wave propagation velocity after AVC (end-systole) is related to myocardial contractility. Methods Firstly, 11 healthy volunteers (age: 25 ± 4 years; male: n = 11) performed a supine bicycle exercise test. Images were taken at rest and during 25%, 50% and 66% of maximal workload, as determined by previous upright bicycle exercise testing. Secondly, 9 patients (age: 63 ± 10 years; male: n = 7) underwent a dobutamine stress echocardiography. The stress echo was negative in all patients. Images were taken at rest and after a dobutamine administration of 10µg/kg/min and 40µg/kg/min. Left ventricular (LV) parasternal long axis views were acquired with an experimental HFR ultrasound scanner (HD-PULSE) (average frame rate: 1217 ± 233fps). Apical 4-chamber views were acquired with a conventional ultrasound machine. Non-invasive single beat end-systolic elastance (Ees) was used as a measure of contractility. Acceleration maps were created from HFR-datasets by drawing a M-mode line along the midline of the interventricular septum. Shear wave propagation speed at AVC (end-systole) was calculated by measuring the slope of the wave front on the acceleration maps (Figure A). Results During the bicycle exercise, heart rate (61 ± 11bpm vs. 146 ± 13bpm; p < 0.001), systolic blood pressure (125 ± 12mmHg vs. 173 ± 15mmHg; p < 0.001), LV ejection fraction (55 ± 3% vs. 70 ± 5%; p < 0.001), Ees (1.8 ± 0.3mmHg/ml vs. 3.6 ± 1.0mmHg/ml; p < 0.001) and propagation velocity of the shear waves (3.3 ± 0.5m/s vs. 6.2 ± 1.7m/s; p < 0.01) (Figure B) increased significantly from rest to exercise. Likewise, dobutamine administration significantly increased the heart rate (68 ± 10bpm vs. 131 ± 14bpm; p < 0.001), LV ejection fraction (57 ± 5% vs. 74 ± 7%; p < 0.001), as well as the shear wave velocity after AVC (4.4 ± 0.6m/s vs. 7.2 ± 1.7m/s; p < 0.01) (Figure C) and Ees (2.1 ± 0.4mmHg/ml vs. 3.3 ± 0.8mmHg/ml; p < 0.001). Independent from the stressor, shear wave propagation velocity had a good and significant correlation with Ees (Figure D). Conclusion Shear wave propagation velocity after AVC increases with increasing level of exercise or dobutamine dose. Shear wave velocities at AVC show a good correlation with Ees. Our data indicate that end-systolic shear wave velocity is related to myocardial contractility and might therefore be a potential novel parameter for the non-invasive assessment of myocardial function. Abstract 156 Figure.

Abstract 16916: Shortening of Pressure Half Time During Exercise as a Predictor for Exercise Capacity in Patients With Bileaflet Mitral Valve Replacement

Introduction: In patients with mechanical mitral valve replacement (MVR), effective orifice area is fixed during dynamic exercise. Therefore, pressure half time (PHT) change during exercise might be mainly influence by exercise-induced left ventricular end-diastolic pressure raise. Hypothesis: We hypothesized that shortening of PHT during supine bicycle exercise would predict exercise capacity in patients with bileaflet mechanical MVR. Methods: Patients with isolated bileaflet MVR (n = 40) prospectively underwent symptom-limited supine bicycle exercise testing with Doppler echocardiography. Heart rate (HR), peak and mean transprosthetic gradient, PHT, and systolic pulmonary artery pressure (SPAP) were assessed at different stages of exercise. Changes in PHT during 25W and 50W exercise (ΔPHT-25W and ΔPHT-50W, respectively) were measured. Changes in HR during 25W and 50W exercise (ΔHR-25W and ΔHR-50W, respectively) were calculated. Results: There were significant negative correlations between exercise duration and ΔPHT-25W (r = -0.345, p = 0.032) or ΔPHT-50W (r = -0.369, p = 0.027) ( Figure A and B ). Exercise duration demonstrated independent significant correlation with both ΔPHT-25W (p = 0.018) and ΔPHT-50W (p = 0.006), even after adjusting for age, sex, and ΔHR-25W/50W, respectively. Conclusion: Degree of PHT shortening during 25W and 50W exercise predicted exercise capacity in patients with bileaflet mechanical MVR. More shortened PHT during exercise was associated with low exercise capacity, which might be associated with diastolic dysfunction resulted from exercise-induced left ventricular end-diastolic pressure raise.

Development of Mitral Stenosis After Mitral Valve Repair: Importance of Mitral Valve Area

BackgroundThe development of mitral stenosis (MS) is not uncommon after mitral valve (MV) repair for degenerative mitral regurgitation (MR), but the significance of MS in this setting has not been defined. MethodsWe prospectively studied 110 such patients who underwent supine bicycle exercise testing to assess intracardiac hemodynamics at rest and at peak exercise. B-type natriuretic peptide (BNP) levels were measured at rest and after the exercise test. The patients also performed the 6-minute walk test and completed the 36-Item Short Form Survey (SF-36). Follow-up was performed by a review of the medical record and telephone interview. ResultsOf 110 patients, 22 had MS defined by a mitral valve area (MVA) ≤ 1.5 cm2. The resting and peak exercise mitral gradients and pulmonary artery systolic pressure were significantly higher in patients with MS compared with patients with an MVA > 1.5 cm2. BNP levels at rest and after exercise were also higher in the patients with MS, who also had lower exercise capacity and worse perception of well-being in 3 domains (physical function, vitality, and social function) on the SF-36. MVA had higher specificity and positive predictive value in predicting outcome events compared with a mean gradient of 3 or 5 mm Hg. ConclusionsIn patients who had MV repair for degenerative MR, an MVA ≤ 1.5 cm2 occurs in about one-fifth of patients and is associated with adverse intracardiac hemodynamics, lower exercise capacity, and adverse outcomes.

Effective Orifice Area during Exercise in Bileaflet Mechanical Valve Prostheses

The aims of this study were to investigate the evolution of the transprosthetic pressure gradient and effective orifice area (EOA) during dynamic bicycle exercise in bileaflet mechanical heart valves and to explore the relationship with exercise capacity. Patients with bileaflet aortic valve replacement (n=23) and mitral valve replacement (MVR; n=16) prospectively underwent symptom-limited supine bicycle exercise testing with Doppler echocardiography and respiratory gas analysis. Transprosthetic flow rate, peak and mean transprosthetic gradient, EOA, and systolic pulmonary artery pressure were assessed at different stages of exercise. EOA at rest, midexercise, and peak exercise was 1.66±0.23, 1.56±0.30, and 1.61±0.28cm2, respectively (P=.004), in aortic valve replacement patients and 1.40±0.21, 1.46±0.27, and 1.48±0.25cm2, respectively (P=.160), in MVR patients. During exercise, the mean transprosthetic gradient and the square of transprosthetic flow rate were strongly correlated (r=0.65 [P<.001] and r=0.84 [P<.001] for aortic valve replacement and MVR, respectively), conforming to fundamental hydraulic principles for fixed orifices. Indexed EOA at rest was correlated with exercise capacity in MVR patients only (Spearman ρ=0.68, P=.004). In the latter group, systolic pulmonary artery pressures during exercise were strongly correlated with the peak transmitral gradient (ρ=0.72, P<.001). In bileaflet mechanical valve prostheses, there is no clinically relevant increase in EOA during dynamic exercise. Transprosthetic gradients during exercise closely adhere to the fundamental pressure-flow relationship. Indexed EOA at rest is a strong predictor of exercise capacity in MVR patients. This should be taken into account in therapeutic decision making and prosthesis selection in young and dynamic patients.

Abstract 18506: Right Ventricular and Pulmonary Vascular Reserve in Heart Failure With Preserved Ejection Fraction: An Exercise Cardiac Magnetic Resonance Study

Introduction: Right ventricular dysfunction (RVD) is a marker of adverse outcome in HFpEF patients. While RVD in HFpEF has been demonstrated using dobutamine stress and invasive hemodynamic studies, detailed assessment of RV and pulmonary vascular (PV) function using simultaneous exercise cardiac MRI and invasive hemodynamic measurements has never been performed. Methods In a prospective study, we performed CPET to determine maximal power output (Pmax) in patients with HFpEF (n=11, age 73±9 years) and in healthy controls (n=8, age 53±7 years). We also investigated asymptomatic subjects with echocardiographic evidence of LV concentric remodeling (LVCR) and impaired relaxation (n=4, age 63±7 years). All participants then performed a three-stage supine bicycle exercise test during real-time CMR imaging (at 25%, 50% and 66% of Pmax) with continuous recording of pulmonary arterial pressures using fluid-filled catheters. We determined the ratio of mPAP relative to cardiac output (mPAP/CO slope) as a measure of PV reserve and the change in RV end-systolic pressure volume ratio (dRVESPR) as a measure for RV contractile reserve. Results At rest, there was no difference in LV or RV ejection fraction (EF) between HFpEF patients and controls (p=NS). However, during exercise, HFpEF patients showed a decline in RVEF (-3.9±1.7%), contrasting with a marked increase in RVEF in the control group (+12.49±2.33%, p&lt;0.001 for interaction workload*group, figure 1A). HFpEF patients had a greater mPAP/CO slope (p&lt;0.001, figure 1B) and a significantly lower dRVESPVR (p&lt;0.001) than controls. Interestingly, asymptomatic subjects with LVCR showed an intermediate response to exercise (figure 1A-B). Conclusion In patients with HFpEF, RV functional reserve and pulmonary pressure-flow relationships are markedly impaired. These data suggest an important role for cardiac exercise MRI in phenotyping heart failure patients and guiding RV or pulmonary vasculature targeted therapy.

Mitral Valve Area During Exercise After Restrictive Mitral Valve Annuloplasty: Importance of Diastolic Anterior Leaflet Tethering

BackgroundRestrictive mitral valve annuloplasty (RMA) for secondary mitral regurgitation might cause functional mitral stenosis, yet its clinical impact and underlying pathophysiological mechanisms remain debated. ObjectivesThe purpose of our study was to assess the hemodynamic and clinical impact of effective orifice area (EOA) after RMA and its relationship with diastolic anterior leaflet (AL) tethering at rest and during exercise. MethodsConsecutive RMA patients (n = 39) underwent a symptom-limited supine bicycle exercise test with Doppler echocardiography and respiratory gas analysis. EOA, transmitral flow rate, mean transmitral gradient, and systolic pulmonary arterial pressure were assessed at different stages of exercise. AL opening angles were measured at rest and peak exercise. Mortality and heart failure readmission data were collected for at least 20 months after surgery. ResultsEOA and AL opening angle were 1.5 ± 0.4 cm2 and 68 ± 10°, respectively, at rest (r = 0.4; p = 0.014). EOA increased significantly to 2.0 ± 0.5 cm2 at peak exercise (p < 0.001), showing an improved correlation with AL opening angle (r = 0.6; p < 0.001). Indexed EOA (EOAi) at peak exercise was an independent predictor of exercise capacity (maximal oxygen uptake, p = 0.004) and was independently associated with freedom from all-cause mortality or hospital admission for heart failure (p = 0.034). Patients with exercise EOAi <0.9 cm2/m2 (n = 14) compared with ≥0.9 cm2/m2 (n = 25) had a significantly worse outcome (p = 0.048). In multivariate analysis, AL opening angle at peak exercise (p = 0.037) was the strongest predictor of exercise EOAi. ConclusionsIn RMA patients, EOA increases during exercise despite fixed annular size. Diastolic AL tethering plays a key role in this dynamic process, with increasing AL opening during exercise being associated with higher exercise EOA. EOAi at peak exercise is a strong and independent predictor of exercise capacity and is associated with clinical outcome. Our findings stress the importance of maximizing AL opening by targeting the subvalvular apparatus in future repair algorithms for secondary mitral regurgitation.

Abstract 19570: Diastolic Anterior Leaflet Tethering Contributes to Functional Mitral Stenosis after Restrictive Mitral Valve Annuloplasty

Introduction: Restrictive mitral valve annuloplasty (RMA) for secondary mitral regurgitation (MR) might cause functional (mitral) stenosis, yet underlying pathophysiological mechanisms remain debated. Hypothesis: Diastolic restriction of the anterior leaflet (AL) opening, due to papillary muscle tethering, plays a key role in the inflow obstruction after RMA. Increasing AL opening during exercise is associated with greater mitral valve area (MVA). Methods: Consecutive RMA patients (n=39, 63±11 years, 77% male) performed a symptom-limited (supine) bicycle exercise test with stepwise Doppler echocardiography and respiratory gas analysis. Diastolic AL opening angle (3-chamber view, Figure A), transmitral flow rate, mean transmitral gradient, and effective MVA were assessed at rest and during peak exercise. Results: At rest, effective MVA (1.5±0.4cm2) correlated moderately to the AL opening angle (68±10°) (r=0.4, p=0.014; Figure B). During exercise, effective MVA increased significantly to 2.0±0.5cm2 (p&lt;0.001), with a stronger correlation to AL opening angle (r=0.6, p&lt;0.001; Figure B). After stratification of the population into tertiles according to increase in AL opening angle during exercise (&lt;=0°, 0-4° and &gt;4° AL angle increase, respectively), a higher increase was significantly associated with greater effective MVA during exercise (p=0.013, Figure C). Patients with AL opening angle &lt;69° at rest (median) and without dynamic AL angle increase of &gt;4° (n=13) had a significantly lower maximal oxygen uptake compared to patients with AL opening angle at rest above the median or a greater dynamic AL angle increase with exercise (n=22) (VO2max 12.5±2.8 versus 16.4±4.7 mL/kg/min, p=0.005). Conclusions: Diastolic restriction of AL opening plays a key role in functional mitral stenosis after RMA for secondary MR. Increasing AL opening at rest, or better AL opening reserve during exercise, are associated with higher MVA and improved exercise capacity.

Arterial Mechanics at Rest and During Exercise in Adolescents and Young Adults After Arterial Switch Operation for Complete Transposition of the Great Arteries

We sought to determine the arterial mechanics at rest and during exercise in adolescents and young adults with complete transposition of the great arteries after arterial switch operation and their relations with neoaortic complications. Thirty patients (22 men) aged 16.2 ± 2.1 years and 22 controls (15 men) were studied. Central and peripheral arterial pulse wave velocities, carotid and radial augmentation indices, and central systolic blood pressure (cSBP) were determined by oscillometry and applanation tonometry, whereas arterial dimensions were measured by 2-dimensional echocardiography. Arterial strain, distensibility, and stiffness were determined at rest and during supine bicycle exercise testing. At rest, patients had significantly higher heart-carotid pulse wave velocity, carotid and radial augmentation indices, and cSBP than controls. At rest and during submaximal exercise, patients had significantly lower aortic strain and distensibility, greater aortic and carotid stiffness, and higher SBP than controls. Dilated aortic sinus found in 23 (76.7%) patients was associated with lower aortic distensibility, greater aortic stiffness, and higher cSBP at rest and lower aortic distensibility and strain at submaximal exercise. Significant aortic regurgitation found in 20% (6 of 30) of patients was associated with significantly higher neoaortic z scores. Multivariate analysis identified aortic stiffness at rest (β = 0.46, p = 0.003) and age at operation (β = 0.44, p = 0.004) as significant determinants of aortic sinus z scores. In conclusion, altered mechanics of the central arteries are present at rest and during exercise in adolescents and young adults after arterial switch operation. These findings may have important implications on progression of neoaortic root dilation, exercise recommendations, and medical therapy.

Utility of Speckle Tracking Echocardiography in Asymptomatic Mild to Moderate Aortic Stenosis at Rest and During Supine Bicycle Exercise Test

Utility of Speckle Tracking Echocardiography in Asymptomatic Mild to Moderate Aortic Stenosis at Rest and During Supine Bicycle Exercise Test

Overweight and Its Association With Aortic Pressure Wave Reflection After Exercise

Obesity is associated with arterial stiffening, left ventricular (LV) hypertrophy, and diastolic dysfunction. However, there is no data regarding dynamic changes in arterial hemodynamics with exercise in overweight subjects. We hypothesized that overweight women would show a different exercise response in wave reflection compared with lean women. A total of 59 overweight and 68 lean nondiabetic women (mean age 63 ± 7 years) underwent symptom-limited supine bicycle exercise testing with simultaneous two-dimensional and Doppler echocardiography. Central hemodynamics including central aortic pressure and augmentation index (AIx) were obtained at rest and immediately after peak exercise using radial artery tonometry. Overweight women showed a higher LV mass index (lean vs. overweight; 40.2 ± 10.2 vs. 45.3 ± 11.0 g/m(2.7), P = 0.007) and a lower early diastolic mitral annular velocity (6.3 ± 1.8 vs. 5.5 ± 1.6 cm/s, P = 0.013) than lean women. Although the two groups did not differ in peripheral and central hemodynamics including AIx (36.3 ± 11.7 vs. 36.8 ± 10.2%, P = 0.830) and AIx normalized for heart rate 75/min (AIx@75, 30.4 ± 11.5 vs. 30.1 ± 9.9%, P = 0.885) at rest, AIx (20.9 ± 11.5 vs. 27.6 ± 10.4%, P = 0.004) and AIx@75 (25.8 ± 10.2 vs. 31.6 ± 7.7%, P = 0.002) at peak exercise were significantly higher in overweight women. In simple correlation analysis, body mass index (BMI) showed significant correlations with AIx, and AIx@75 at peak exercise, whereas no relationships were found with those parameters at rest. Multiple regression analysis showed that BMI was an independent determinant of AIx@75 at peak exercise (β = 0.28, P = 0.004). Despite similar resting peripheral and central hemodynamics, the wave reflection in overweight women after exercise differed from that in lean women. These findings suggest that being overweight is related to higher wave reflection after exercise.

The Effect of Metabolic Syndrome on Myocardial Contractile Reserve during Exercise in Non-Diabetic Hypertensive Subjects

BackgroundMetabolic syndrome (MS) is associated with increased left ventricular (LV) mass and diastolic dysfunction. This study uses relatively load-independent Doppler tissue echocardiography to examine whether MS is associated with decreased longitudinal contractile reserve during dynamic exercise.MethodsA total of 112 patients with relatively well-controlled, treated hypertension who complained of exertional dyspnea were enrolled (average age: 56.7 ± 10.5 years). Fifty-six were non-diabetic patients with MS (Group 1), and 56 were age-sex matched hypertensive patients without MS (Group 2). Exercise stress echo was performed using a symptom-limited, multistage, supine bicycle exercise test. Multiple Doppler parameters were obtained at baseline, at each stage of exercise, and during recovery.ResultsThere was no significant difference between the two groups in terms of age, gender, and hemodynamic variables. E/E', an index of LV filling pressure, was significantly higher in the MS group at rest and during exercise. The longitudinal contractile reserve, the change in S' (longitudinal tissue velocity) from baseline to peak exercise, was significantly lower in the MS group (2.00 ± 1.65 vs. 2.90 ± 1.66, p = 0.015). Multiple regression analysis showed independent association of MS with longitudinal contractile reserve when controlled for confounding factors, such as LV mass index, gender, blood pressure, and age (β = -0.235, p = 0.035).ConclusionLongitudinal contractile reserve was reduced in MS patients compared to others, although both groups demonstrated similar longitudinal contractile function at rest. We present the first demonstration that metabolic syndrome is independently associated with LV systolic dysfunction during exercise in hypertensive patients.

Predictors of exercise capacity and symptoms in severe aortic stenosis

This study investigated the association between invasive and non-invasive estimates of left ventricular (LV) filling pressure and exercise capacity, in order to find new potential candidates for risk markers in severe aortic valve stenosis (AS). Twenty-nine patients with AS, aortic valve area (AVA) < 1 cm(2), performed a symptom-limited multistage supine bicycle exercise test. Immediately before the exercise test, the pulmonary capillary wedge pressure (PCWP), Doppler index for LV filling (E/e'), and left atrial (LA) volume were measured. Symptomatic status was determined by senior staff doctors blinded to the results of this study. All patients terminated the exercise test because of dyspnoea. There were no significant differences in AVA between asymptomatic patients (n = 9) and symptomatic patients (n = 20), and AVA did not correlate with exercise capacity (r = -0.16, P = NS). In contrast, PCWP, LA volume, and E/e' were significantly increased in the symptomatic group and they all correlated with exercise capacity (r = -0.66, -0.75, and -0.62, respectively, P < 0.001). Receiver operating characteristic curve analysis confirmed that PCWP, LA volume index, and E/e' all provided incremental information [area under the curve (AUC) = 0.90, 0.92, and 0.90, respectively, P < 0.05] over AVA index (AUC = 0.66, NS) in predicting symptomatic status. PCWP, LA volume, or E/e' is closely related to exercise capacity and symptomatic status, and may therefore be important markers of disease severity in AS. Clinical Trials.gov Identifier: NCT00252317 (http://clinicaltrials.gov/ct2/results?term=NCT00252317).

Differences in myocardial velocities during supine and upright exercise stress echocardiography in healthy adults

Tissue Velocity Imaging (TVI) is a method for quantitative analysis of longitudinal myocardial velocities, which can be used during exercise and pharmacological stress echocardiography. It is of interest to evaluate cardiac response to different types of stress tests and the differences between upright and supine bicycle exercise tests have not been fully investigated. Therefore, the aim of this study was to compare cardiac response during supine and upright exercise stress tests. Twenty young healthy individuals underwent supine and upright stress test. The initial workload was set to 30 W and was increased every minute by a further 30 W until physical exhaustion. Tissue Doppler data from the left ventricle were acquired at the end of every workload level using a GE Vivid7 Dimension system (>200 frames s(-1)). In the off-line processing, isovolumic contraction velocity (IVCV), peak systolic velocity (PSV), isovolumic relaxation velocity (IVRV), peak early diastolic velocity (E') and peak late diastolic velocity (A') were identified at every workload level. No significant difference between the tests was found in PSV. On the contrary, E' was shown to be significantly higher (P<0.001) during supine exercise than during upright exercise and IVRV was significantly lower (P<0.001) during supine exercise compared to upright exercise. Upright and supine exercise stress echocardiography give a comparable increase in measured systolic velocities and significant differences in early diastolic velocities.

Left Ventricular Filling Pressure Estimation at Rest and During Exercise in Patients With Severe Aortic Valve Stenosis: Comparison of Echocardiographic and Invasive Measurements

The Doppler index of left ventricular (LV) filling (E/e') is recognized as a noninvasive measure for LV filling pressure at rest but has also been suggested as a reliable measure of exercise-induced changes. The aim of this study was to investigate changes in LV filling pressure, measured invasively as pulmonary capillary wedge pressure (PCWP), at rest and during exercise to describe the relation with E/e' in patients with severe aortic stenosis. Twenty-eight patients with an aortic valve areas<1 cm(2) performed a multistage supine bicycle exercise test until exhaustion. PCWP, E/e'(septal), and E/e'(lateral) were determined simultaneously by echocardiography at rest and at maximal tolerated workload. PCWP increased significantly from 18+/-8 mm Hg at rest to 39+/-10 mm Hg at peak exercise (P < .0001). E, e'(septal), and e'(lateral) increased with exercise, whereas E/e'(septal) remained unchanged (19+/-6 vs 19+/-6; P=NS), and only minimal changes were observed in E/e'(lateral) (14+/-4 vs 15+/-4; P=.05). E/e'(septal) and E/e'(lateral) were significantly correlated with PCWP at rest (r=0.72, P < .0001, and r=0.67, P < .0001, respectively) as well as at peak exercise (r=0.66, P=.0003, and r=0.47, P=.02, respectively), with nearly similar slopes of the linear regression lines. The intercepts, however, increased by 18 mm Hg (P=.01) and by 19 mm Hg (P=.01) at peak exercise, respectively. Changes in E/e'(septal) and E/e'(lateral) were not related to changes in PCWP with exercise (P=NS). Instead, the ratio of E velocity during exercise to e'(septal) at rest (E(exercise)/e'(septal, rest)) was correlated with PCWP during exercise (r=0.61, P=.001), and furthermore, E(exercise)-E(rest)/e'(septal, rest) was related to changes in PCWP (r=0.45, P=.02). The results for the lateral side were r=0.50 (P=.01) and r=0.44 (P=.03), respectively. E/e' is well correlated with PCWP at rest. However, E/e' cannot be used to detect exercise-induced changes in PCWP in patients with severe aortic stenosis. Using the ratio of E during exercise to e' at rest may result in a better estimate of the increase in PCWP during exercise.

Effect of Geometric Remodeling on Left Ventricular Longitudinal Contractile Reserve in Patients with Hypertension

Left ventricular hypertrophy (LVH) is associated with a reduction of subendocardial coronary flow reserve, which may be associated with abnormal myocardial longitudinal function during exercise. To test this hypothesis, 182 hypertensive patients underwent multistage supine bicycle exercise testing. Patients were classified as follows: patients with normal geometry (group 1, n = 116), concentric remodeling (group 2, n = 31), or LVH (group 3, n = 31). The results showed that the ratio of E/E', an index of left ventricular (LV) filling pressure, was significantly elevated in the LVH group at rest and during exercise. At rest, the mitral annular systolic velocity (S') was similar between the three groups at rest, whereas S' during exercise was significantly lower in the LVH group. The magnitude of change in S' during exercise was also significantly lower in the LVH group. Multiple linear regression analysis showed that peak double product (beta = 0.208, P = .006) and LV mass index (beta = -0.158, P = .028) were independently associated with LV longitudinal contractile reserve. Also, multiple linear regression analysis showed that changes in S' from baseline to peak were independently associated with exercise duration (beta = 0.123, P = .041) when controlled for age, male gender, baseline E', peak systolic blood pressure, and LV mass index. The results from this study demonstrate that LVH was significantly associated with abnormal LV longitudinal contractile reserve in hypertensive patients.

ST-T integral and T-wave amplitude in detection of exercise-induced myocardial ischemia evaluated with body surface potential mapping

Body surface potential mapping is superior to 12-lead electrocardiogram in detection of acute and old myocardial infarctions. We examined the capability of the ST-T integral and T wave to detect exercise-induced ischemia in body surface potential mapping. Body surface potential mapping with 123 channels was recorded in 70 subjects: 45 coronary artery disease (CAD) patients and 25 healthy controls during supine bicycle exercise testing. Of the patients, 18 had anterior, 14 posterior, and 13 inferior ischemia documented by coronary angiography and thallium scintigraphy. The ST-T isointegral area, as well as the positive and negative ST-T area, and the T-wave apex amplitude were determined. Discriminant index analysis was used to find the sites that optimally separated patient subgroups from other patients and controls. In the pooled CAD group, the optimal sites for detecting the decrease in ST-T isointegral, in the positive ST-T area and in the T-wave amplitude were over the left side (ST-T isointegral area: CAD −3.8 ± 14 μVs and controls 24 ± 14 μVs; T-wave amplitude: CAD 3 ± 110 μV and controls 190 ± 90 μV; P < .001, both). The area under the receiver operating characteristic curve for the decrease in ST-T isointegral, in the positive ST-T area, and in the T-wave amplitude and for the ST depression were 94%, 95%, 92%, and 93%, respectively. T wave performed especially well in patients with multivessel disease. In stepwise logistic regression analysis, using the presence of CAD as the dependent parameter, the decrease in the positive ST-T area and ST depression were the only parameters that entered the model. ST-T area and T-wave amplitude are sensitive and specific markers of transient myocardial ischemia. ST-T area contains information additional to ST depression and has thus independent discriminative value in ischemia detection.

Features of ST segment and T-wave in exercise-induced myocardial ischemia evaluated with multichannel magnetocardiography

BACKGROUND AND AIM. Magnetocardiography (MCG) is a novel, non-contact mapping technique to record cardiac magnetic field. We evaluated MCG criteria for myocardial ischemia in stress testing. METHODS. Multichannel MCG over frontal chest was performed in 44 patients with coronary artery disease (CAD) and 26 healthy controls during supine bicycle exercise test. Of the 44 patients 16 had anterior, 15 posterior, and 13 inferior ischemia documented by coronary angiography and exercise thallium scintigraphy. ST amplitude, ST slope, T-wave amplitude, and ST-T integral were measured. The optimal sites for detecting the ischemiainduced changes on MCG were sought. The orientation of the magnetic field was also determined. RESULTS. The optimal sites for the decrease of ST slope, ST amplitude, T-wave amplitude, and ST-T integral were over the abdomen. The reciprocal increase of these parameters was found over the left parasternal area. The optimal sites were approximately the same for all patient groups. In single-vessel disease patients without previous myocardial infarction (MI), ST slope increase and ST elevation performed the best (area under the receiver operating characteristic curve 92% and 90%, respectively). In post-MI patients with triple-vessel disease the decrease of T-wave amplitude and ST slope performed the best (area under curve 91%, for both). The magnetic field orientation at ST segment performed equally well as the other ST parameters. In stepwise logistic regression analysis, by use of the presence of CAD as the dependent parameter, ST slope increase and ST peak gradient orientation entered the model. CONCLUSIONS: Various ST segment and T-wave parameters detect ischemia in MCG. ST amplitude performs especially well in non-MI patients with less severe CAD. In advanced CAD late development of T-wave amplitude might be more sensitive to ischemia than ST amplitude.

ST-segment level and slope in exercise-induced myocardial ischemia evaluated with body surface potential mapping

Body surface potential mapping (BSPM) is superior to 12-lead electrocardiography for detection of acute and old myocardial infarctions (MIs). We used BSPM to examine electrocardiographic criteria for acute reversible myocardial ischemia. BSPM with 123 channels was performed in 45 patients with coronary artery disease (CAD) and 25 healthy controls during supine bicycle exercise testing. Of the 45 patients, 18 patients had anterior, 14 had posterior, and 13 had inferior ischemia documented by coronary angiography and thallium scintigraphy. The ST amplitude was measured 60 ms after the J-point and the ST slope calculated by fitting a regression line from the J-point to 60 ms after it. The optimal locations for detecting ST depression and ST-slope decrease were identified. In the pooled CAD patient group, the optimal location for ST depression was 5 cm below standard lead V 5 (CAD group: −70 ± 70 μV; controls: 70 ± 80 μV, p <0.001). Using a cut-off value of −10 μV, the ST depression separated the patients with CAD from controls with a sensitivity of 84% and a specificity of 96%. The ST slope became more horizontal in the patient group than in the control group. The optimal location for ST-slope decrease was over the left side (CAD group: 20 ± 20 μV/s; controls: 720 ± 320 μV/s, p <0.001). Using a cut-off value of 320 μV/s, the ST slope separated patients with CAD from controls with a sensitivity of 93% at a specificity level of 88%. The area under the receiver operating characteristic curve of ST slope tended to be higher than the one of ST depression (97% vs 93%; p = 0.097). In conclusion, regions sensitive for ST depression and for ST-slope decrease could be identified in BSPM, despite variation in the location of ischemia and the presence or absence of a history of MI. ST slope is a sensitive and specific marker of transient myocardial ischemia, and might perform even better than ST depression.

The warm-up effect protects against ischemic left ventricular dysfunction in patients with angina

OBJECTIVESThe goal of this study was to investigate whether the “warm-up” effect in angina protects against ischemic left ventricular (LV) dysfunction.BACKGROUNDAfter exercise, patients with coronary disease demonstrate persistent myocardial dysfunction, which may represent stunning, as well as warm-up protection against further angina, which may represent ischemic preconditioning. The effect of warm-up exercise on LV function during subsequent exercise has not been investigated.METHODSThirty-two patients with multivessel coronary disease and preserved LV function performed two supine bicycle exercise tests 30 min apart. Equilibrium radionuclide angiography was performed before, during and up to 60 min after each test. Global LV ejection fraction and volume changes and regional ejection fraction for nine LV sectors were calculated for each acquisition.RESULTSOnset of chest pain or 1 mm ST depression was delayed and occurred at a higher rate-pressure product during the second exercise test. Sectors whose regional ejection fraction fell during the first test showed persistent reduction at 15 min (68 ± 20 vs. 73 ± 20%, p < 0.0001). These sectors demonstrated increased function during the second test (71 ± 20 vs. 63 ± 20%, p = 0.0005). The reduction at 15 min and the increase during the second test were both in proportion to the reduction during the first test. Effects on global function were only apparent when the initial response to exercise was considered.CONCLUSIONSThe warm-up effect is accompanied by protection against ischemic regional LV dysfunction. The degree of stunning and protection after exercise is related to the severity of dysfunction during exercise, consistent with results from experimental models.