Aortic Pressure Waveform Research Articles

Aortic pulse wave velocity and reflecting distance estimation from peripheral waveforms in humans: detection of age- and exercise training-related differences

We hypothesized that demographic/anthropometric parameters can be used to estimate effective reflecting distance (EfRD), required to derive aortic pulse wave velocity (APWV), a prognostic marker of cardiovascular risk, from peripheral waveforms and that such estimates can discriminate differences in APWV and EfRD with aging and habitual endurance exercise in healthy adults. Ascending aortic pressure waveforms were derived from peripheral waveforms (brachial artery pressure, n = 25; and finger volume pulse, n = 15) via a transfer function and then used to determine the time delay between forward- and backward-traveling waves (Δtf-b). True EfRDs were computed as directly measured carotid-femoral pulse wave velocity (CFPWV) × 1/2Δtf-b and then used in regression analysis to establish an equation for EfRD based on demographic/anthropometric data (EfRD = 0.173·age + 0.661·BMI + 34.548 cm, where BMI is body mass index). We found good agreement between true and estimated APWV (Pearson's R² = 0.43; intraclass correlation = 0.64; both P < 0.05) and EfRD (R² = 0.24; intraclass correlation = 0.40; both P < 0.05). In young sedentary (22 ± 2 years, n = 6), older sedentary (62 ± 1 years, n = 24), and older endurance-trained (61 ± 2 years, n = 14) subjects, EfRD (from demographic/anthropometric parameters), APWV, and 1/2Δtf-b (from brachial artery pressure waveforms) were 52.0 ± 0.5, 61.8 ± 0.4, and 60.6 ± 0.5 cm; 6.4 ± 0.3, 9.6 ± 0.2, and 8.1 ± 0.2 m/s; and 82 ± 3, 65 ± 1 and 76 ± 2 ms (all P < 0.05), respectively. Our results demonstrate that APWV derived from peripheral waveforms using age and BMI to estimate EfRD correlates with CFPWV in healthy adults. This method can reliably detect the distal shift of the reflecting site with age and the increase in APWV with sedentary aging that is attenuated with habitual endurance exercise.

Non-invasive method for the aortic blood pressure waveform estimation using the measured radial EBI

The paper presents a method for the Central Aortic Pressure (CAP) waveform estimation from the measured radial Electrical Bio-Impedance (EBI). The method proposed here is a non-invasive and health-safe approach to estimate the cardiovascular system parameters, such as the Augmentation Index (AI). Reconstruction of the CAP curve from the EBI data is provided by spectral domain transfer functions (TF), found on the bases of data analysis. Clinical experiments were carried out on 30 patients in the Center of Cardiology of East-Tallinn Central Hospital during coronary angiography on patients in age of 43 to 80 years. The quality and reliability of the method was tested by comparing the evaluated augmentation indices obtained from the invasively measured CAP data and from the reconstructed curve. The correlation coefficient r = 0.89 was calculated in the range of AICAP values from 5 to 28. Comparing to the traditional tonometry based method, the developed one is more convenient to use and it allows long-term monitoring of the AI, what is not possible with tonometry probes.

Lower potassium intake is associated with increased wave reflection in young healthy males

Increased potassium intake has been shown to lower blood pressure (BP) even in the presence of high sodium consumption however the role of dietary potassium on vascular function has received less attention. The objective of this study was to evaluate the relationship between habitual intake of sodium (Na) and potassium (K) and measures of arterial stiffness and wave reflection. 20 healthy males (24±0.7 yrs; systolic BP 121±3; diastolic BP 64±2 mmHg) recorded their dietary intake for 3 days and collected their 24‐hr urine on the 3rd day. Carotid‐femoral pulse wave velocity (PWV) and the synthesis of a central aortic pressure waveform (by radial artery applanation tonometry and generalized transfer function) were performed. Aortic augmentation index (AI), an index of wave reflection, was calculated from the aortic pressure waveform. Subjects consumed an average of 2,492 kcals, 4,212 mg Na, and 2,967 mg of K. Average urinary Na/K excretion ratio was 2.69±0.3. An inverse relationship between AI and K excretion was found (r= −0.3122; p&lt;0.001) while no relationship was noted with Na excretion (r= − 0.005; p&gt;;0.05). AI positively correlated with the Na/K excretion ratio (r= 0.153; p&lt;0.05). PWV did not correlate with either nutrient or the Na/K excretion ratio (p&gt;;0.05). These data suggest that lower potassium intakes are associated with stiffer arteries in young healthy males. Supported by R01 HL 104106.

Guidelines on guidelines

Current guidelines on isolated systolic hypertension (ISH) suggest the same treatment to patients of all ages. Application of these guidelines in youth with ISH may not be appropriate, as presently no data show adverse outcome or benefit of drug therapy in this group. Simple noninvasive tonometric techniques now enable physicians to measure the central aortic pressure waveform and amplification of the pressure pulse. ISH in youth is usually caused by high amplification of the central pressure wave, whereas ISH in the elderly (>age 60) is attributable to aortic stiffening. This is the only group with ISH shown to have an adverse prognosis and to warrant drug therapy.

Notch Transcriptional Control of Vascular Smooth Muscle Regulatory Gene Expression and Function

Notch receptors and ligands mediate heterotypic cell signaling that is required for normal vascular development. Dysregulation of select Notch receptors in mouse vascular smooth muscle (VSM) and in genetic human syndromes causes functional impairment in some regional circulations, the mechanistic basis of which is undefined. In this study, we used a dominant-negative Mastermind-like (DNMAML1) to block signaling through all Notch receptors specifically in VSM to more broadly test a functional role for this pathway in vivo. Mutant DNMAML1-expressing mice exhibited blunted blood pressure responses to vasoconstrictors, and their aortic, femoral, and mesenteric arteries had reduced contractile responses to agonists and depolarization in vitro. The mutant arteries had significant and specific reduction in the expression and activity of myosin light chain kinase (MLCK), a primary regulator of VSM force production. Conversely, activated Notch signaling in VSM cells induced endogenous MLCK transcript levels. We identified MLCK as a direct target of activated Notch receptor as demonstrated by an evolutionarily conserved Notch-responsive element within the MLCK promoter that binds the Notch receptor complex and is required for transcriptional activity. We conclude that Notch signaling through the transcriptional control of key regulatory proteins is required for contractile responses of mature VSM. Genetic or pharmacological manipulation of Notch signaling is a potential strategy for modulating arterial function in human disease.

Aortic pressure wave reflection in patients after successful aortic arch repair in early infancy

Despite the apparently successful surgical repair of aortic coarctation, subsequent cardiovascular complications have sometimes been encountered. Aortic pressure wave reflection is one of the risk factors for developing cardiovascular diseases, and an enhancement of the pressure wave reflection has been reported in patients after aortic arch repair. To clarify this issue, the increase in pressure wave reflection was evaluated in patients <15 years old who underwent aortic arch repair. This study enrolled 35 patients after aortic arch repair in early infancy. All patients underwent cardiac catheterization, and in 20 patients, there was no pressure difference within the repaired aortic arch. The aortic pressure waveforms in patients after successful aortic arch repair were recorded using a pressure sensor-mounted catheter, and the augmentation index in the ascending aorta was calculated. The augmentation index in patients after an aortic arch repair was increased compared with control subjects, although there was no pressure difference between the ascending and descending aorta (P<0.0001). The increase in the augmentation index was correlated with the patient's age (r=0.8932, P<0.0001) and with the left ventricular posterior wall thickness (r=0.4075, P=0.0373). In patients who undergo aortic arch repair, the pressure wave reflection is accelerated, even when the aortic arch repair is 'successful'. This increase is one of the possible causes of left ventricular hypertrophy.

Comparative Study on Tube-Load Modeling of Arterial Hemodynamics in Humans

In this paper, we assess the validity of two alternative tube-load models for describing the relationship between central aortic and peripheral arterial blood pressure (BP) waveforms in humans. In particular, a single-tube (1-TL) model and a serially connected two-tube (2-TL) model, both terminated with a Windkessel load, are considered as candidate representations of central aortic-peripheral arterial path. Using the central aortic, radial and femoral BP waveform data collected from eight human subjects undergoing coronary artery bypass graft with cardiopulmonary bypass procedure, the fidelity of the tube-load models was quantified and compared with each other. Both models could fit the central aortic-radial and central aortic-femoral BP waveform pairs effectively. Specifically, the models could estimate pulse travel time (PTT) accurately, and the model-derived frequency response was also close to the empirical transfer function estimate obtained directly from the central aortic and peripheral BP waveform data. However, 2-TL model was consistently superior to 1-TL model with statistical significance as far as the accuracy of the central aortic BP waveform was concerned. Indeed, the average waveform RMSE was 2.52 mmHg versus 3.24 mmHg for 2-TL and 1-TL models, respectively (p < 0.05); the r² value between measured and estimated central aortic BP waveforms was 0.96 and 0.93 for 2-TL and 1-TL models, respectively (p < 0.05). We concluded that the tube-load models considered in this paper are valid representations that can accurately reproduce central aortic-radial/femoral BP waveform relationships in humans, although the 2-TL model is preferred if an accurate central aortic BP waveform is highly desired.

The Effects of Acute Beta-Adrenergic Blockade on Aortic Wave Reflection in Postmenopausal Women

BACKGROUND Acute beta-adrenergic blockade increases aortic-wave reflection in young women. However, it is not known whether this effect extends to postmenopausal women. We therefore examined the effect of systemic beta-adrenergic blockade on aortic wave reflection in 14 postmenopausal women with a mean age of 58±2 years. METHODS Aortic pressure waveforms were synthesized noninvasively from high-fidelity radial pressure waveforms obtained through applanation tonometry before and during systemic beta-blockade with propranolol given in a bolus dose of 0.25mg/kg, followed by a continuous infusion at 0.004mg/kg/min. To further examine the effects of acute beta-blockade on aortic-wave reflection in postmenopausal women, we compared the changes in hemodynamics and indices of aortic-wave reflection with published data from a previous study with a protocol identical to that in the present study but which involved young women. RESULTS Acute beta-blockade increased the aortic augmentation index (AIx) in postmenopausal women (32±2% vs. 35±2%, P < 0.01). However, AIx adjusted for a heart rate of 75 bpm (AIx75) was unchanged (25±2% vs. 24±2%, P > 0.05). The changes in AIx, AIx75, and the amplitude of reflected waves (augmented aortic pressure) during beta-blockade were all substantially smaller in postmenopausal women than in their younger counterparts (P < 0.05). Conclusions As compared with those in our previously published study involving young women, indices of aortic-wave reflection were significantly less affected by acute systemic beta-adrenergic blockade in the postmenopausal women in the present study. Taken together, our data suggest that the negative effects (i.e. increased aortic wave reflection) of nonselective beta-adrenergic blockade are less pronounced in postmenopausal than in young women.

A “backward” calculation method for the estimation of central aortic pressure wave in a 1D arterial model network

The central aortic pressure waveform plays an important role in medicine. Several clinical outcomes can be determined using this information. However, direct measurement is difficult and risky, so that estimation methods are preferred. In the current paper a novel method is introduced which is a new basis for this estimation process. A one-dimensional arterial model is created using basic equations of fluid dynamics and a viscoelastic material model. In case of “forward” calculation the volumetric flow rate curve of the heart is set as a boundary condition. Pressure, velocity, wave propagation speed and deformation are calculated in the whole network. In case of “backward” calculation the pressure waveform is given at an arbitrary point of the network. With modification of the equations the calculation is turned backwards: knowing a pressure waveform at the downstream end of a vessel segment, the pressure waveform at the upstream end is calculated. The central aortic pressure waveform can be estimated within the 1D arterial model using this method. Details of the computation method and results of testing calculations are presented. The developed method is a powerful tool that might be used for central aortic pressure wave estimation in the future.

Pulse wave analysis of aortic pressure

The systolic augmentation index (sAix), calculated from the central aortic pulse wave (reconstructed from the noninvasive recording of the radial pulse with applanation tonometry), is widely used as a simple index of central arterial stiffness, but has the disadvantage of also being influenced by the timing of the reflected with respect to the forward pressure wave, as shown by its inverse dependence on heart rate (HR). During diastole, the central aortic pulse also contains reflected waves, but their relationship to arterial stiffness and HR has not been studied. In 48 men and 45 women, all healthy, with ages ranging from 19 to 70 years, we measured pulse wave velocity (PWV, patients supine), a standard evaluator of arterial stiffness, and carried out radial applanation tonometry (patients sitting and supine). The impact of reflected waves on the diastolic part of the aortic pressure waveform was quantified in the form of a diastolic augmentation index (dAix). Across ages, sexes, and body position, there was an inverse relationship between the sAix and the dAix. When PWV and HR were added as covariates to a prediction model including age, sex and body position as main factors, the sAix was directly related to PWV (P < 0.0001) and inversely to HR (P < 0.0001). With the same analysis, the dAix was inversely related to PWV (P < 0.0001) and independent of HR (P = 0.52). The dAix has the same degree of linkage to arterial stiffness as the more conventional sAix, while being immune to the confounding effect of HR. The quantification of diastolic aortic pressure augmentation by reflected waves could be a useful adjunct to pulse wave analysis.

Arterial Wave Reflections and Incident Cardiovascular Events and Heart Failure: MESA (Multiethnic Study of Atherosclerosis)

This study sought to assess the relationship between central pressure profiles and cardiovascular events (CVEs) in a large community-based sample. Experimental and physiologic data mechanistically implicate wave reflections in the pathogenesis of left ventricular failure and cardiovascular disease, but their association with these outcomes in the general population is unclear. Aortic pressure waveforms were derived from a generalized transfer function applied to the radial pressure waveform recorded noninvasively from 5,960 participants in the Multiethnic Study of Atherosclerosis. The central pressure waveform was separated into forward and reflected waves using a physiologic flow waveform. Reflection magnitude (RM = [Reflected/Forward wave amplitude] × 100), augmentation index ([Second/First systolic peak] × 100) and pulse pressure amplification ([Radial/aortic pulse pressure] × 100) were assessed as predictors of CVEs and congestive heart failure (CHF) during a median follow-up of 7.61 years. After adjustment for established risk factors, aortic AIx independently predicted hard CVEs (hazard ratio [HR] per 10% increase: 1.08; 95% confidence interval [CI]: 1.01 to 1.14; p = 0.016), whereas PPA independently predicted all CVEs (HR per 10% increase: 0.82; 95% CI: 0.70 to 0.96; p = 0.012). RM was independently predictive of all CVEs (HR per 10% increase: 1.34; 95% CI: 1.08 to 1.67; p = 0.009) and hard CVEs (HR per 10% increase: 1.46; 95% CI: 1.12 to 1.90; p = 0.006) and was strongly predictive of new-onset CHF (HR per 10% increase: 2.69; 95% CI: 1.79 to 4.04; p < 0.0001), comparing favorably to other risk factors for CHF as per various measures of model performance, reclassification, and discrimination. In a fully adjusted model, compared to nonhypertensive subjects with low RM, the HRs (95% CI) for hypertensive subjects with low RM, nonhypertensive subjects with high RM, and hypertensive subjects with high RM were 1.81 (0.85 to 3.86), 2.16 (1.07 to 5.01), and 3.98 (1.96 to 8.05), respectively. Arterial wave reflections represent a novel strong risk factor for CHF in the general population.

Fibrinogen and d-dimer in contrasting relation with measures of wave reflection and arterial stiffness

Introduction. The relationship between the results of coagulation tests and measures of arterial stiffness or wave reflection has been investigated in different diseases. This exploratory study aimed at the evaluation of similar associations in healthy individuals. Material and methods. Pulse wave analysis of reconstructed aortic pressure waveform for the central augmentation index, augmentation pressure and pulse pressure, and digital volume pulse for the stiffness index were measured at supine rest in 91 healthy volunteers (54.1 ± 8.5 years; 56 female). Standard coagulation tests for the d-dimer and fibrinogen concentrations were performed in fasting venous blood. Results. In univariate linear regression d-dimer and fibrinogen concentrations were significantly and positively, although weakly, associated with measures related to pulse wave analysis. Multivariate linear regression adjusted to subjects’ age, resting pulse rate and mean blood pressure showed that the d-dimer concentration was significantly related to central augmentation index (p = 0.014), augmentation pressure (p = 0.003) and pulse pressure (p = 0.029) whereas fibrinogen was linked to the stiffness index (p = 0.04). Higher concentrations of d-dimers and fibrinogen are associated with increased arterial stiffness and faster pulse wave propagation in healthy people and the observed associations are independent of typical determinants of the shapes of pulse pressure waveforms like age, pulse rate and mean blood pressure. Conclusions. The independent relationships between the results of the coagulation tests and pulse wave analysis suggest that the existence of such associations may indicate a biologically plausible phenomenon.

Beat-to-beat estimation of the continuous left and right cardiac elastance from metrics commonly available in clinical settings

IntroductionFunctional time-varying cardiac elastances (FTVE) contain a rich amount of information about the specific cardiac state of a patient. However, a FTVE waveform is very invasive to directly measure, and is thus currently not used in clinical practice. This paper presents a method for the estimation of a patient specific FTVE, using only metrics that are currently available in a clinical setting.MethodCorrelations are defined between invasively measured FTVE waveforms and the aortic and pulmonary artery pressures from 2 cohorts of porcine subjects, 1 induced with pulmonary embolism, the other with septic shock. These correlations are then used to estimate the FTVE waveform based on the individual aortic and pulmonary artery pressure waveforms, using the “other” dysfunction’s correlations as a cross validation.ResultsThe cross validation resulted in 1.26% and 2.51% median errors for the left and right FTVE respectively on pulmonary embolism, while the septic shock cohort had 2.54% and 2.90% median errors.ConclusionsThe presented method accurately and reliably estimated a patient specific FTVE, with no added risk to the patient. The cross validation shows that the method is not dependent on dysfunction and thus has the potential for generalisation beyond pulmonary embolism and septic shock.

612 RELATIONSHIP BETWEEN ARTERIAL STIFFNESS AND HEART RATE RECOVERY

Background: Arterial stiffness and heart rate recovery (HRR) following exercise testing have emerged as factors holding significant prognostic value. The relationship between arterial stiffness and HRR has, however, not been investigated. Methods: HRR was measured at 1- minute time points after treadmill testing in 538 patients being evaluated for chest pain. Arterial stiffness, wave reflections and central blood pressure were quantified noninvasively using applanation tonometry of the radial artery with a validated transfer function to generate the corresponding ascending aortic pressure wave form. Results: Pearson correlation analysis revealed a significant correlation between augmentation Index and HRR. Multiple linear regression analysis showed the age, heart rate, augmentation index were positive predictors of HRR (r= 0.23 r2= 0.052, p<0.024). Conclusions: This cross-sectional study indicate that HRR is significantly correlated with aortic stiffness. Further studies are now required to identified the mechanism underling this newly described association.

347 THE VIS-A-TERGO FOR CEREBRAL PERFUSION

Background: While requiring high steady flow, the brain is perfused in a pulsatile manner. Changes in flow pulsation have been linked to stroke. Flow pulsations in normal subjects have not been characterised, nor their relationship to pulsatile perfusion pressure. Methods: Data were obtained in 200 persons (age 52 years, 94 males), undergoing 24-hour BP monitoring for outpatient evaluation. Flow waveforms were recorded by transcranial Doppler in the right and left Anterior Cerebral, Middle Cerebral, and Basilar Arteries (ACA, MCA and BA, respectively). Radial artery tonometry was used with SphygmoCorTM to generate Ascending Aortic Pressure waveform (AP). Results: Similar flow waveforms were seen on the right and left sides for ACA and MCA. Mean flow velocity was high in all (ACA 54, MCA 61 and BA 38 cm/s, respectively), and continued throughout diastole. Flow waves showed prominent late systolic augmentation, more marked in the smaller BA than ACA or MCA. Flow augmentation index (FAI), calculated in similar fashion to aortic pressure, increased with age at all sites, but was higher in smaller (BA; 112%) than larger arteries (ACA; MCA; 93%) and in all, systematically greater than Pressure Augmentation Index. Conclusions: Wave reflection from the lower body increases Ascending Aortic pressure in late systole. This is caused by wave reflection from the lower body (vis-a-tergo). Wave reflection also boosts late systolic flow in the major cerebral arteries. Value of reduction in wave reflection by arterial dilating drugs needs be explored.

76 COMPARISON OF THE USE OF CENTRAL AND PERIPHERAL PRESSURE WAVEFORMS FOR OPTIMIZATION OF CARDIAC RESYNCHONIZATION THERAPY

Background: In patients with cardiac dyssynchrony, optimization of cardiac resynchronization therapy (CRT) is achieved by ascertaining the atrial-ventricular (AV) and inter-ventricular (VV) delays that give maximum cardiac output (CO). As continuous CO measurements are not readily available, this study assesses the use of the peripheral (radial) and central aortic pressure waveform for optimal AV and VV delay using a haemodynamic model. Methods: The model consisted of left and right heart chambers simulated by time varying elastance (variable capacitors), systemic and pulmonary sections simulated by windkessel segments (resistance, capacitance) and a delay line for the arm. Model parameters were altered to obtain maximal values (optimization criterion) for central and peripheral systolic, diastolic and pulse pressure (cSBP, cDBP, cPP, pSBP, pDBP, pPP) and CO from baseline settings of AV (120 ms) and VV (0 ms) delays. Results: The optimal AV delay was not different for all hemodynamic measures. However, optimal VV delay was significantly different for blood pressure parameters compared to CO (*p<0.001).Conclusions: The study indicates that both peripheral and central pressure parameters give similar results for CRT optimisation for AV and VV delay. However optimization for pressure parameters gives significant differences for VV delay compared to CO. This suggests that the ventricular -vascular coupling is an important parameter to be considered for CRT optimisation.

Beneficial Effect of Vardenafil on Aortic Stiffness and Wave Reflections

Although vardenafil is widely prescribed for erectile dysfunction (ED), its effect on arterial function is not defined. Aortic stiffness, aortic pressures, and wave reflections are predictors of cardiovascular risk. The investigators assessed the hypothesis that vardenafil acutely improves aortic stiffness, aortic pressures, and wave reflections in ED patients. Twelve ED patients (mean age 58 ± 9 years) received vardenafil 20 mg in a randomized, placebo-controlled, double-blind, 2-way crossover design. Aortic stiffness was evaluated with carotid-femoral pulse wave velocity (PWV); wave reflections and aortic pressures were evaluated with augmentation index (AIx) and systolic, diastolic, and pulse pressure of the aortic pressure waveform, respectively. PWV, aortic pressures, and AIx were measured at baseline and for 3 hours after vardenafil intake or placebo. PWV decreased significantly (by 0.7 m/s, P = .001), denoting a decrease in aortic stiffness. AIx decreased significantly (by 7%, P = .008), denoting a decreased effect of wave reflections from the periphery. Aortic pressures decreased significantly (all P < .05). Statin use at baseline significantly interacted with the effects of treatment on both PWV and AIx (P = .003 and P < .001, respectively). This study shows, for the first time, that vardenafil has a favorable acute effect on aortic stiffness and wave reflection in ED patients.

Algorithmic processing of pressure waveforms to facilitate estimation of cardiac elastance

BackgroundCardiac elastances are highly invasive to measure directly, but are clinically useful due to the amount of information embedded in them. Information about the cardiac elastance, which can be used to estimate it, can be found in the downstream pressure waveforms of the aortic pressure (Pao) and the pulmonary artery (Ppa). However these pressure waveforms are typically noisy and biased, and require processing in order to locate the specific information required for cardiac elastance estimations. This paper presents the method to algorithmically process the pressure waveforms.MethodsA shear transform is developed in order to help locate information in the pressure waveforms. This transform turns difficult to locate corners into easy to locate maximum or minimum points as well as providing error correction.ResultsThe method located all points on 87 out of 88 waveforms for Ppa, to within the sampling frequency. For Pao, out of 616 total points, 605 were found within 1%, 5 within 5%, 4 within 10% and 2 within 20%.ConclusionsThe presented method provides a robust, accurate and dysfunction-independent way to locate points on the aortic and pulmonary artery pressure waveforms, allowing the non-invasive estimation of the left and right cardiac elastance.

Comparison of two generalized transfer functions for measuring central systolic blood pressure by an oscillometric blood pressure monitor

Central aortic systolic blood pressure (SBP-C) can be estimated from a cuff oscillometric waveform derived during the pulse volume plethysmography (PVP) by applying a device-specific aortic pressure-to-PVP waveform-generalized transfer function (A2P(GTF)). The present study compared the performance of an aortic-to-brachial pressure waveforms generalized transfer function (A2B(GTF)), which is independent of any PVP devices, with an A2P(GTF). Generalized transfer function of aortic-to-brachial (A2B(GTF)) and aortic-to-PVP (A2P(GTF)) were generated from the simultaneously obtained central aortic and brachial pressure waveforms recorded by a high-fidelity dual pressure sensor catheter, and the PVP waveform recorded by a customized noninvasive blood pressure monitor during cardiac catheterization in 40 patients, and were then applied in another 100 patients with simultaneously recorded invasive aortic pressure and noninvasively calibrated (using cuff SBP and diastolic blood pressures) PVP waveforms. The mean difference±s.d. between the noninvasively estimated and invasively recorded SBP-C was -2.1±7.7 mm Hg for A2B(GTF), which was not greater than that of -3.0±7.7 mm Hg for A2P(GTF) (P<0.01). In conclusion, SBP-C can be measured reliably using a noninvasive blood pressure monitor by applying either an A2P(GTF) or A2B(GTF) to a noninvasively calibrated PVP waveform. The performance of an A2B(GTF) is not inferior to that of an A2P(GTF).

Aortic reservoir function, estimated myocardial demand and coronary perfusion pressure following steady‐state and interval exercise

Aortic reservoir function is a measure of the aorta's ability to distribute blood during diastole, attenuating the pulsatility of blood flow, and is important in balancing cardiac flow. Effects of acute high versus moderate exercise intensity on reservoir function and cardiac energetics is unknown. Eighteen athletes completed a interval (INT) and steady-state (SS) cycling bout at 60% of VO(2) peak. Reservoir function was calculated as the ratio of diastolic run-off to stroke volume and expressed as a percentage. Coronary perfusion pressure was derived from tissue Doppler imaging and echocardiography. Systolic tension-time integral (TTI) from the aortic pressure waveform served as a measure of myocardial oxygen consumption. All measures were made at rest, 30-min postexercise and 60-min postexercise. Average reservoir function before SS was 76%, which was reduced to 62% 30-min post-SS and 67% 60-min post-SS (P<0.05). Significantly greater reductions in reservoir function were seen following INT (from 71% pre-INT to 45% 30-min post-INT and 53% 60-min INT, P<0.05). Estimated coronary perfusion pressure was reduced 30min following INT but not SS; both bouts reduced coronary perfusion pressure at 60-min postexercise (P<0.05). TTI increased following both INT and SS at 30- and 60-min postexercise with greater increases following INT (P<0.05). Following exercise, reservoir function was associated with TTI (P<0.05), but not coronary perfusion pressure (P>0.05). We conclude that reservoir function is attenuated following acute SS and INT, but these reductions were greater post-INT, suggesting that exercise intensity affects reservoir function. Reduction of reservoir function following exercise is related to TTI, a reflection of myocardial oxygen consumption but apparently not associated with coronary perfusion pressure.