Carotid Artery Longitudinal Wall Motion Research Articles

The influence of physical activity and sex on carotid artery longitudinal wall motion in younger healthy adults.

Carotid artery longitudinal wall motion (CALM) is a novel preclinical marker for atherosclerosis that describes the axial anterograde and retrograde motion of the intima-media complex. While regular physical activity and sex are known to independently influence arterial stiffness, their roles on axial arterial wall behaviour are unknown. The purpose of this study is to examine whether physical activity and sex impact CALM. We hypothesized that CALM retrograde displacement and total amplitude would be greater in females and active individuals, as a function of arterial stiffness. Fifty-seven young healthy adults (30 females; aged 22±3 years) were evaluated for CALM outcomes and arterial stiffness and grouped by physical activity based on active (V̇O2=44.2±8.9mL/kg/min) or sedentary (V̇O2=33.7±6.7mL/kg/min) lifestyles defined by the Canadian 24-Hour Movement Guidelines. Arterial stiffness and CALM were measured by carotid-femoral pulse wave velocity (cfPWV) and vascular ultrasound at the right common carotid artery with speckle tracking analysis, respectively. cfPWV was greater in males (p<0.01) with no interaction between sex and physical activity (p=0.90). CALM anterograde displacement was greater in males (p=0.03) resulting in a forward shift in total CALM pattern, which became less prominent when controlling for mean arterial pressure (p=0.06). All other CALM outcomes were not different between activity and sex. V̇O2max was not correlated to any CALM outcome (all p>0.05). Apparent sex differences in vascular function extend to novel CALM outcomes but may be confounded by blood pressure. We recommend sex-balanced design and reporting in future studies due to possible anterograde-shifted CALM patterns in healthy males.

The influence of respiration, neck flexion, and arterial segment on carotid artery longitudinal wall motion.

While carotid artery longitudinal wall motion (CALM) has been highly detailed in cross-sectional studies, there is little evidence to explain population inter-individual variability. This study was conducted to investigate how common external factors impact CALM. Twenty-one young healthy adults (11 females, aged 22±2 years) underwent three within-subject protocols. To evaluate probe positioning, vascular ultrasound was performed at a proximal and distal location along the common carotid artery. To evaluate neck angle, scans were acquired with the neck positioned at 70°, 90°, maximum extension (112±9°), and maximum flexion (51±7°). For the respiratory cycle condition, scans were taken during 7 sec of inhalation, 7 sec of exhalation, and 7 sec of breath hold. CALM was evaluated for anterograde, retrograde, and maximum displacements, as well as radial-axial displacement. CALM was greater at proximal vs. distal locations (retrograde = 1.14±0.62 vs. 0.63±0.24 mm, maximal = 1.32±0.59 vs. 0.73±0.24 mm; all p<0.05). Minimum neck angles had greater motion than maximum angles (maximum displacement = 1.03±0.43 vs. 0.77±0.23 mm, p<0.05). Without correcting breathing bias, retrograde displacement was greater during inspiration vs. expiration (1.06±0.34 vs. 0.58±0.24 mm) and breath hold (1.06±0.34 vs. 0.58±0.24 mm), diastolic CALM was greater during expiration vs. breath hold (1.10±0.44 vs. 0.76±0.33 mm), and maximum CALM was smaller during breath hold vs. expiration (0.89±0.31 vs. 1.21±0.39 mm) and inspiration (0.89±0.31 vs. 1.41±0.70 mm). We recommend scanning 1-2 cm proximal to the carotid bifurcation, maintaining a neutral neck angle (70-90°) for optimal CALM data collection in humans.

Case Studies in Physiology: Using premature ventricular contractions to understand the regulation of carotid artery longitudinal wall motion

Recent observations have identified a distinct longitudinal motion pattern of the common carotid artery, where the wall oscillates along its length both with (anterograde) and against (retrograde) the direction of blood flow. The regulation of the longitudinal pattern remains largely undetermined, in part due to difficulty uncoupling local pressure and flow stimuli from upstream energy sources. In this case study of a 29-yr-old male, we examine the regulation of longitudinal wall motion from the perspective of spontaneous premature ventricular contractions (PVCs). With respect to the pre-PVC beat, during the PVC, there was an 81% reduction in carotid blood velocity (96.8 to 18.4 cm/s), a 69% reduction in pulse pressure (58 to 18 mmHg), and a 59% reduction in apical left ventricular (LV) rotation (6.9 to 2.8°) as a result of reduced LV filling time. During this time, anterograde longitudinal wall motion was unchanged (0.06 mm), whereas retrograde motion was reduced by 91% (0.75 to 0.07 mm). During the compensated post-PVC beat, there were large increases in all outcomes, except for anterograde wall motion. Taken together, there appears to be little influence of either local or upstream factors on anterograde wall motion. Although retrograde wall motion generally mirrored blood pressure, blood velocity, and upstream cardiac movement, the primary motion regulator remains unclear. In this Case Study, we provide evidence against the role of blood velocity in regulating local wall motion and reinforce the potential importance of cardiac mechanics dictating the unique longitudinal motion pattern at the common carotid artery.NEW & NOTEWORTHY Benign arrhythmias can be a useful tool to probe new hypotheses in physiology. We tested the control of longitudinal motion of the common carotid artery wall using observations from spontaneous premature ventricular contractions in a healthy male. Forwards wall motion remained unchanged despite large deviations in local blood velocity and backwards wall motion mirrored changes in pulse pressure, blood velocity, and cardiac motion, thereby revising our original hypothesis of the control of longitudinal wall motion.

Carotid artery longitudinal wall motion alterations associated with metabolic syndrome and insulin resistance.

Our objective was to study relationships between the new biomarker of vascular health, carotid artery longitudinal wall motion (CALM) and metabolic syndrome (MetS). Carotid ultrasound and assessment of MetS and its components were performed with 281 subjects aged 30-45years. In the longitudinal motion analysis, the amplitude of motion and the antegrade-oriented and retrograde-oriented components of motion between the intima-media complex and adventitial layer of the common carotid artery wall were assessed. Metabolic syndrome, according to the harmonized criteria, was detected in 53 subjects (19%). MetS was significantly associated with increased antegrade and decreased retrograde longitudinal motion in the carotid artery wall. Augmented antegrade amplitude of longitudinal motion was associated with obesity (β=0.149, p<.05) and low HDL cholesterol (β=0.177, p<.01). Attenuated retrograde amplitude of longitudinal motion was associated with hypertension (β=-0.156, p<.05), obesity (β=-0.138, p<.05) and hyperinsulinaemia (β=-0.158, p<.01). Moreover, insulin resistance (homeostasis model assessment index above 2.44) was associated with adverse changes in CALM. Metabolic syndrome and insulin resistance were associated with alterations in CALM. In particular, hypertension, obesity and hyperinsulinaemia were associated with reduced total peak-to-peak amplitude as well as increased antegrade and reduced retrograde amplitudes, all of which might be markers of unfavourable vascular health.

Carotid Artery Longitudinal Wall Motion Is Unaffected by 12 Weeks of Endurance, Sprint Interval or Resistance Exercise Training

Carotid artery longitudinal wall motion (CALM) exhibits reduced magnitude in older adults and in individuals with chronic diseases, although longitudinal data are lacking to indicate how changes in CALM might develop over time. Therefore, the aim of this study was to investigate the effect of exercise training in healthy men on CALM using a retrospective design. Carotid ultrasound data were analysed from two previous studies in which men performed 12 wk of moderate-intensity continuous exercise training (n = 9), sprint-interval training (n = 7), higher-repetition resistance exercise training (n = 15) or lower-repetition resistance exercise training (n = 15). The CALM pattern was unaltered after 12 wk of exercise training, regardless of exercise mode, with no differences in systolic or diastolic CALM magnitudes (p > 0.05), similar to carotid intima-media thickness (p > 0.05). Our findings suggest that CALM is resistant to transient changes in lifestyle factors, similar to wall thickness in otherwise healthy populations.

Retrograde shift in carotid artery longitudinal wall motion after one-year follow-up in children

Background and aimsCross-sectional studies suggest that arterial stiffness increases during childhood; however, this evidence stems from pressure-dependent arterial distension, while longitudinal movement of the arterial wall has not been explored. Carotid artery longitudinal wall motion (CALM) has been identified as a novel biomarker of vascular health in adults and may provide complementary biaxial wall information to vascular changes during childhood development. Accordingly, the purpose of this study was to assess how CALM changes and tracks over a one-year period in young children. MethodsChildren were recruited from the Health Outcomes and Physical activity in Preschoolers study (n = 114; 65 girls; age: 5.8 ± 0.9 years-old). CALM was measured at the left common carotid artery using ultrasound with speckle tracking. ResultsThere were increases in CALM magnitudes over one-year follow-up, including systolic retrograde, diastolic, maximum, and total radial-axial displacement (all p < 0.01), with no differences between boys and girls. With the exception of systolic anterograde displacement, all CALM variables tracked better in girls than in boys, both individually (Spearman's ρ ranges: 0.49–0.61 vs. 0.25–0.47), as well as when split into tertile groups (Cohen's weighted κ ranges: 0.43–0.60 vs. 0.16–0.44), indicating overall moderate tracking (κ > 0.40) in the entire cohort. ConclusionsCALM displacements change rapidly during childhood and track into pre-pubescence in a sex-specific manner. These findings suggest that CALM is influenced by individual factors that track consistently, and that similar to arterial stiffness, it may be valuable to examine the age-associated changes in CALM magnitudes to infer changes in child vascular health over time.

Associations between carotid artery longitudinal wall motion and arterial stiffness indicators in young children

Background and aimsCarotid artery longitudinal wall motion (CALM) is associated with established indicators of arterial stiffness in healthy adults and in adults with cardiovascular disease risk factors. CALM assessment may be more feasible for incorporation into routine clinical examination than traditional assessments of arterial stiffness; however, the relationship between CALM and arterial stiffness in children has not been established. MethodsData were collected from a subset of children participating in the Health Outcomes and Physical activity in Preschoolers study. CALM was characterized by segmental longitudinal wall displacement, velocity, and acceleration. Arterial stiffness was measured using whole-body pulse wave velocity (PWV) and carotid artery β-stiffness index. Associations between CALM and arterial stiffness and the influence of age, sex, and height on those associations were determined. ResultsOne hundred and ninety-one children (ages 5.0–8.0 years) were included in the analyses. Systolic retrograde (r = -0.20, p = 0.01) and maximum (r = -0.15, p = 0.04) CALM displacements were weakly correlated with PWV while systolic anterograde and diastolic CALM displacements and wall velocities and accelerations were not correlated with PWV (r = -0.12 to −0.03, p = 0.10 to 0.64). There were no significant correlations between any CALM outcome and β-stiffness index (r = -0.12 to 0.10; p > 0.05). Associations were attenuated after adjusting for age, sex, and height. ConclusionsHigher arterial stiffness, measured by PWV, but not β-stiffness, is weakly associated with less longitudinal movement of the common carotid artery in young, healthy children indicating CALM measurement is not a strong candidate for clinical assessment of arterial stiffness in children.

An assessment of intra-individual variability in carotid artery longitudinal wall motion: recommendations for data acquisition

Objective: To assess the intra-individual variation in carotid artery longitudinal wall motion (CALM) in healthy adults in order to determine the amount of data required to generate a representative measurement of CALM. Approach: We conducted an analysis of 27 healthy men to determine whether calculation of resting individual CALM outcomes is dependent on the number of averaged heart cycles. CALM was assessed at rest, 1–2 cm proximal to the right carotid bifurcation during a breath hold and was segmented into three motion displacements: systolic anterograde CALM, systolic retrograde CALM, and diastolic CALM. A 2D measure of total carotid artery motion (RALength) was also determined from the longitudinal and radial displacements. Outcomes were averaged discretely using two, three, four, five, and six consecutive heart cycles to assess the impact of additional data on intra-individual coefficients of variation (CV%) and intra-class correlations (ICC). Main results: Calculated means were similar between all heart cycle averaging for CALM displacements (all P > 0.05), though the two-heart cycle average of RALength (P = 0.06) was reduced in comparison to all other averages. Averaging data from four heart cycles was sufficient to generate a plateau in the variability in resting CALM displacements, such that within-subject ICC values all reached >0.90 and CV% were similar to previously reported day-to-day variability in healthy adults. Significance: There is variability in beat-to-beat measures of CALM that should be considered when designing protocols for data collection and analysis. We suggest that four consecutive heart cycles should be averaged to generate representative resting CALM outcomes in humans. While indices of variability were reduced when assessing outcomes generated from two to four heart cycles, no further improvements were observed when more heart cycles were included, indicating that averaging more than four heart cycles is likely not required.

Carotid artery longitudinal wall motion: regulatory factors and implications for arterial health.

The carotid artery wall moves longitudinally along the length of the vessel, although little is known about what causes this motion, or what health information it represents. The overarching purpose of this dissertation was to investigate the regulation of carotid artery longitudinal wall motion (CALM) in humans, as well as how CALM can be used to infer information about arterial health. Through observational and experimental designs, we tested evidence for a structural ventricular-vascular coupling effect, which postulates that systolic anterograde CALM is influenced by the forward blood shear rate while systolic retrograde CALM is influenced by left ventricular rotation, although the data suggest a moderate influence of left ventricular rotation, and minimal influence of shear rate. In cross-sectional analyses, we demonstrated that diastolic CALM variables are better related to age and health status compared with systolic CALM displacement and that this relationship was independent of traditional measures of arterial stiffness. These experimental and observational results directed the use of diastolic CALM as a potential indicator of arterial health in subsequent studies, owing to the relative independence from systolic events. While there was no effect of 12 weeks of exercise training in healthy men on diastolic CALM variables, we observed increased systolic retrograde CALM and diastolic CALM acceleration in men with a history of resistance exercise training compared with sedentary men, suggesting an effect of habitual exercise training. Our novel findings suggest that CALM is regulated by a complex system, in part related to both arterial wall structure and ventricular-vascular coupling, and may have clinical value in complimenting measures of traditional arterial stiffness in humans. Future studies should examine whether local changes to arterial wall structure or indirect changes in regulatory control dictate differences in CALM with aging and with chronic exercise training, before integrating CALM into routine measurement of arterial health.

Cardiac and haemodynamic influence on carotid artery longitudinal wall motion.

What is the central question of this study? Carotid artery longitudinal wall motion (CALM) is a bidirectional forward and backward motion of the arterial wall; however, there is no evidence in humans for what controls CALM despite proposals for pulse pressure, left ventricular motion and shear rate. What is the main finding and its importance? Carotid artery longitudinal wall motion responses were heterogeneous when manipulating sympathetic activation and endothelium-independent vasodilatation, leading to non-significant group responses. However, individual CALM responses were associated with left ventricular rotation and shear rate. These findings are important when interpreting changes in CALM in humans with acute or chronic experimental designs. Carotid artery longitudinal wall motion (CALM) has recently attracted interest as an indicator of arterial health; however, the regulation of CALM is poorly understood. We conducted a series of studies aimed at manipulating pulse pressure (PP), left ventricular (LV) motion and carotid shear rate, which have been previously suggested to regulate various components of CALM pattern and magnitude. To determine the regulatory influences on CALM, 15 healthy men (22±2years old) were exposed to three acute interventions: the serial subtraction test (SST); the cold pressor test (CPT); and exposure to sublingual nitroglycerine (NTG). The SST elicited increases in PP (P<0.01), apical LV rotation (P<0.01) and carotid shear rate (P<0.01), with no changes in CALM (P>0.05). Likewise, the CPT elicited increases in PP (P=0.01), basal LV rotation (P=0.04) and carotid shear rate (P=0.01), with no changes in CALM (P>0.05). Conversely, exposure to NTG elicited no change in PP (P=0.22), basal (P=0.65) or apical LV rotation (P=0.45), but did decrease carotid shear rate (P<0.01), without altering CALM (P>0.05). Considerable individual variability in CALM responses prompted further analyses where all three interventions were pooled for change scores. Changes in LV basal rotation were related to changes in systolic retrograde CALM (B=-0.025, P=0.03), whereas changes in carotid shear rate were related to changes in diastolic CALM displacement (B=0.0009, P=0.01). The interventions were underpinned by relationships between CALM and both LV basal rotation and local shear rate at the individual level, indicating that cardiac and haemodynamic factors may influence CALM in humans.

Diastolic Carotid Artery Longitudinal Wall Motion Is Sensitive to Both Aging and Coronary Artery Disease Status Independent of Arterial Stiffness

We investigated the ability of systolic and diastolic carotid artery longitudinal wall motion (CALM) to delineate expected differences in arterial health in individuals representing a range of both age and health status. We recruited 161 younger healthy adults (aged 24 ± 5 y), 51 older healthy adults (aged 70 ± 5 y) and 14 adults with coronary artery disease (aged 67 ± 8 y) for resting assessment of CALM and arterial stiffness. All CALM parameters were reduced in the old healthy adults and adults with coronary artery disease compared with the young healthy adults (p < 0.01), with diastolic velocity and maximum diastolic acceleration being further reduced in the adults with coronary artery disease than in the older healthy adults (p < 0.01). Diastolic CALM parameters were more strongly related to age (β range: −0.46 to −0.53) than systolic CALM parameters (β range: −0.24 to −0.44). In contrast to previous examinations of a variety of CALM parameters, diastolic CALM may provide superior promise in terms of characterizing arterial wall properties, with additional sensitivity to cardiovascular disease status.

Carotid artery longitudinal wall motion is associated with local blood velocity and left ventricular rotational, but not longitudinal, mechanics.

Recent studies have identified a predictable movement pattern of the common carotid artery wall in the longitudinal direction. While there is evidence that the magnitude of this carotid artery longitudinal wall motion (CALM) is sensitive to cardiovascular health status, little is known about the determinants of CALM. The purpose of this integrative study was to evaluate the contribution of left ventricular (LV) cardiac motion and local blood velocity to CALM. Simultaneous ultrasound measurements of CALM, common carotid artery mean blood velocity (MBV), and left ventricular motion were performed in ten young, healthy individuals (6 males; 22 ± 1 years). Peak anterograde CALM occurred at a similar time as peak MBV (18.57 ± 3.98% vs. 18.53 ± 2.81% cardiac cycle; t‐test: P = 0.94; ICC: 0.79, P < 0.01). The timing of maximum retrograde CALM displacement was different, but related, to both peak apical (41.00 ± 7.81% vs. 35.33 ± 5.79% cardiac cycle; t‐test: P < 0.01; ICC: 0.79, P < 0.01) and basal rotation (41.80 ± 6.12% vs. 37.30 ± 5.66% cardiac cycle; t‐test: P < 0.01; ICC: 0.74, P < 0.01) with peak cardiac displacements preceding peak CALM displacements in both cases. The association between basal rotation and retrograde CALM was further supported by strong correlations between their peak magnitudes (r = −0.70, P = 0.02), whereas the magnitude of septal longitudinal displacement was not associated with peak CALM (r = 0.11, P = 0.77). These results suggest that the rotational mechanical movement of the LV base may be closely associated with longitudinal mechanics in the carotid artery. This finding may have important implications for interpreting the complex relationship between ventricular and vascular function.

Reduced common carotid artery longitudinal wall motion and intramural shear strain in individuals with elevated cardiovascular disease risk using speckle tracking.

Longitudinal motion of the intima-media and adventitia layers of the common carotid artery (CCA) wall were assessed with ultrasound speckle tracking in seven individuals with spinal cord injury (SCI), who are considered at increased risk of cardiovascular disease, and in seven able-bodied participants. CCA longitudinal wall displacement and intramural shear strain were compared to traditional markers of arterial health, including CCA stiffness and intima-media thickness (IMT). For each cardiac cycle, longitudinal CCA wall motion was characterized by bidirectional movement patterns containing motion retrograde to blood flow during systole, followed by antegrade motion during diastole. Relative displacement of the intima-media versus the adventitia was used to calculate longitudinal intramural shear strain and provided insight to local arterial wall properties. The retrograde intramural shear strain was smaller in individuals with SCI by 60·2% (P<0·05) compared to able-bodied participants, showing smaller peak displacements in both the intima-media (P<0·05) and adventitia (P<0·05). In the antegrade direction, there were no group differences in either longitudinal displacements or shear strain. The group differences observed in the retrograde wall motion phase were greater than those observed for CCA stiffness or IMT and were found to be independent of both indices, indicating indices of the retrograde phase intramural shear strain may be a novel and sensitive marker of vascular health. Our findings demonstrate that assessment of longitudinal arterial wall shear strain may provide valuable insight into vascular structure and function and may hold potential for the early detection of cardiovascular disease.