Degree Of Constriction Research Articles

Study of the effects of vocal tract constriction on glottal vibration.

Characteristics of glottal vibration are affected by the obstruction to the flow of air through the vocal tract system. The obstruction to the airflow is determined by the nature, location, and extent of constriction in the vocal tract during production of voiced sounds. The effects of constriction on glottal vibration are examined for six different categories of speech sounds having varying degree of constriction. The effects are examined in terms of source and system features derived from the speech and electroglottograph signals. It is observed that a high degree of constriction causing obstruction to the flow of air results in large changes in these features, relative to the adjacent steady vowel regions, as in the case of apical trill and alveolar fricative sounds. These changes are insignificant when the obstruction to the airflow is less, as in the case of velar fricative and lateral approximant sounds. There are no changes in the excitation features when there is a free flow of air along the auxiliary tract, despite constriction in the vocal tract, as in the case of nasals. These studies show that effects of constriction can indeed be observed in the features of glottal vibration as well as vocal tract resonances.

Influence of glottal cross-section shape on phonation onset.

Phonation models commonly rely on the assumption of a two-dimensional glottal geometry to assess kinetic and viscous flow losses. In this paper, the glottal cross-section shape is taken into account in the flow model in order to capture its influence on vocal folds oscillation. For the assessed cross-section shapes (rectangular, elliptical, or circular segment) the minimum pressure threshold enabling to sustain vocal folds oscillation is altered for constriction degrees smaller than 75%. The discrepancy between cross-section shapes increases as the constriction degree decreases.

Effect of pertussis toxin on calcium influx in three contraction models

Pertussis toxin (PTX) blocks G protein activation and inhibits signal transmission from the activated receptor to effectors that are specific for the G protein-coupled receptor. The aim of the present study was to evaluate the effect of PTX on vascular smooth muscle cells that were stimulated pharmacologically with phenylephrine (α-adrenoceptor agonist), mastoparan-7 (direct G-protein activator) and Bay K8644 (direct calcium channel activator). The changes in perfusion pressure that were proportional to the degree of phenylephrine-induced constriction of rat tail arteries were assessed. Concentration-response curves (CRCs) that were obtained for phenylephrine, mastoparan-7 and Bay K8644 presented a sigmoidal association. A significantly reduced calcium influx to the cytoplasm in the presence of mastoparan-7 resulted in a significant rightward shift of the CRCs with a significant reduction in maximal responses. The presence of PTX did not change mastoparan-7 and Bay K8644-induced contraction, whereas the significant inhibition of phenylephrine-induced contraction was found. The results of the experiments indicated that PTX significantly inhibited phenylephrine-induced contraction of vascular smooth muscle cells by inhibition of calcium influx from the intra- and extracellular calcium space. PTX did not change the smooth muscle contraction that was induced by mastoparan-7 and Bay K8644. The predominant effect of mastoparan-7 may be associated with other binding sites as compared to the G-protein or PTX may bind to other sites than mastoparan-7.

A Prospective Study of Correlation between Clinical Disability and Radiological Features in Degenerative Lumbar Canal Stenosis (LCS)

Introduction The relationship between clinical disability and various parameters such as degree of constriction of dural sac, radiological pelvic parameters, facet joint orientation in patients with degenerative LCS has not been clearly defined. Materials and Methods A total of 50 patients with LCS were selected prospectively and divided into two groups (20 patients responding to conservative therapy and 30 requiring surgery) and compared with 16 controls. Patients were clinically evaluated by Oswestry disability index (ODI), SF-12, and neurogenic claudication outcome score (NCOS). All patients underwent anteroposterior, lateral dynamic radiographs of lumbar spine, and whole spine standing lateral radiograph. The spinopelvic parameters measured were spinosacral angle, thoracic kyphosis, lumbar lordosis, pelvic incidence, sacral slope, and pelvic tilt. Dural sac cross-sectional area, lateral recess angle and height, and facet joint orientation were assessed in MRI. Results Between conservative and operated group, the mean ODI score (55.5 vs. 62.99, p = 0.014) and NCOS (37.7 vs. 29.47, p = 0.06) were significantly different. Dural sac area significantly differed ( p < 0.001) between control (113.97 ± 57.58), conservative (47.57 ± 24.77), and operated groups (20.66 ± 14.49). NCOS had significant positive correlation with dural sac area ( r = 0.296, p = 0.037) than ODI. In patients with degenerative spondylolisthesis, there was a significant sagittal orientation of facet joints, high pelvic incidence (58.79 vs. 50.57, p = 0.047), and an increased pelvic tilt (18.99 vs. 11.25, p = 0.045). Conclusion Degree of dural sac stenosis corresponds to clinical disability and NCOS is a better indicator of dural sac compression than ODI score. LCS patients with sagittal facet orientation, high pelvic incidence, and high pelvic tilt develop spondylolisthesis. Disclosure of Interest None declared

The path from trilling to frication: Synthesizing Puerto Rican Spanish velar fricative realizations of apical trills

Puerto Rican Spanish (PRS) speakers variably produce velar fricative realizations of etymological apical trills. One way to understand this alternation is by attributing it to the two types of trill realization having different gestural goals in PRS. Alternatively, both types of realization may be the result of invariant gestural goals that give rise to distinct attractor states. This study tests whether invariant articulator tasks specified for PRS apical trills can result in successfully synthesized trill and fricative realizations. Comparative measures present in the acoustics of tokens of both types of realization as recorded by native PRS speakers serve as landmarks to determine the success of the articulator model used to produce the synthesized versions. Manipulation of tongue tip gestural stiffness on the one hand and constriction degree on the other provide a way to test which parameter values best capture a bi-goal articulator task. While these findings do not argue against the possibility that PRS velar fricative realizations arise from gestural goals that differ from their apical trill counterparts, they show that this possibility is not the only candidate account for the alternation exhibited in PRS.

Metformin Protects Against Systolic Overload–Induced Heart Failure Independent of AMP-Activated Protein Kinase α2

Activation of AMP-activated protein kinase (AMPK)-α2 protects the heart against pressure overload-induced heart failure in mice. Although metformin is a known activator of AMPK, it is unclear whether its cardioprotection acts independently of an AMPKα2-dependent pathway. Because the role of AMPKα1 stimulation on remodeling of failing hearts is poorly defined, we first studied the effects of disruption of both the AMPKα1 and AMPKα2 genes on the response to transverse aortic constriction-induced left ventricular (LV) hypertrophy and dysfunction in mice. AMPKα2 gene knockout significantly exacerbated the degree of transverse aortic constriction-induced LV hypertrophy and dysfunction, whereas AMPKα1 gene knockout had no effect on the degree of transverse aortic constriction-induced LV hypertrophy and dysfunction. Administration of metformin was equally effective in attenuating transverse aortic constriction-induced LV remodeling in both wild-type and AMPKα2 knockout mice, as evidenced by reduced LV and lung weights, a preserved LV ejection fraction, and reduced phosphorylation of mammalian target of rapamycin (p-mTOR(Ser2448)) and its downstream target p-p70S6K(Thr389). These data support the notion that activation of AMPKα1 plays a negligible role in protecting the heart against the adverse effects of chronic pressure overload, and that metformin protects against adverse remodeling through a pathway that seems independent of AMPKα2.

Tongue kinematics in palate relative coordinate spaces for electro-magnetic articulography

This paper describes a method for constructing a three-dimensional model of the hard palate using electro-magnetic articulography, and defines two algorithms to derive constriction degree and constriction location values from the trajectories of tongue coils using this model. The kinematics of tongue motion that have been transformed into constriction degree and constriction location values are investigated in detail to determine whether this type of representation obeys the constraints theorized to operate over higher level motor control. Results show that palate-relative coordinate spaces decouple mechanical dependencies present in the tongue, while maintaining low-level kinematic properties. They additionally preserve the 1/3 power law for speed and curvature observed across many motor systems. Finally, it is shown that tongue movements in a palate relative coordinate space more closely correspond to their optimal, jerk-minimized trajectories. These results suggest that this type of coordinate space provides a closer match to higher level motor-planning, in line with production models that specify control units in terms of vocal tract constriction parameters.

Simulations of sound change resulting from a production-recovery loop

We present a computational model of lenition-based sound change. Speech production targets for constriction degree are modeled by differential equations with a single stable fixed point at the target constriction degree that interact with higher order equations that reflect prosodically conditioned variation. This output is then input to the articulatory-to-acoustic forward map, the quantal nature of which causes continuous variation in constriction degree to result in two outcomes: closure or spirantization. The quantized acoustic outcomes are then used as the input for the language learner, who must recover the produced constriction degree in the ambient language environment to produce the speech unit appropriately. We model this recovery as estimating the parameters of an articulatory distribution that is most likely to have produced the acoustic observations (i.e., the maximum likelihood estimate). In particular, we optimize the parameters of a Gaussian distribution with respect to their log-likelihood function, given the acoustic data that results from applying the quantal forward map to that distribution. We show how this production-recovery loop may lead to sound change in a language by varying the nature of the articulatory-to-acoustic map as well as the amount of knowledge the learner has about both the prosodic structure and articulatory-to-acoustic map.

Characterizing post-glossectomy speech using real-time magnetic resonance imaging

We investigate articulatory behavior in post-glossectomy speech using real-time magnetic resonance imaging. Our data reveal that listeners judge speech produced by partial-glossectomy patients as atypical when the surgical procedure affected the oral tongue. Speech produced by patients whose procedure affected the base of tongue, however, was judged as typical. We observe that preservation and compensation mechanisms are exhibited by the patients with atypical speech. They preserve appropriate modulation of F1 using tongue and/or jaw height despite inability to appropriately modulate F2 due to the reduced size and/or mobility of the tongue. Further, durational differences between tense and lax vowels are maintained. The preservation of these features serves as evidence in support of a framework within which individual gestural parameters are independently controlled; when achievement of a particular parameter specification (e.g., constriction location) is compromised, the remaining (e.g., constriction degree, activation duration) are unchanged. Compensatory behavior is exhibited when coronal tongue movement has been impeded and is exemplified by (i) production of labiodental stops in place of target coronal stops and laterals and (ii) forming a velar constriction to produce frication in place of the alveolar frication for /s/.

Interspeaker variability in relative tongue size and vowel production

The tongue varies across speakers in terms of the proportion of the overall speech production apparatus that it occupies. Differences in tongue size have the potential to result in speaker-specific articulatory strategies for shaping the vocal tract area function and, in turn, individual patterns of vowel acoustics. The present study examines the interplay between relative tongue size and vowel production using real-time magnetic resonance imaging with synchronous audio. Two populations of native American English subjects are considered, one containing healthy adult speakers with no relevant pathologies, and another containing speakers who had undergone glossectomy as treatment for tongue cancer. All subjects were imaged in the midsagittal plane while reading phonetically balanced English sentences. The size of the tongue and the speech production apparatus were quantified from an overall average posture, and their ratio was correlated with the shape of the vowel space in terms of acoustics (e.g., formant frequencies), constrictions (i.e., location and degree of minimum constriction), and parameterized vocal tract cross-distance functions. Results indicate that relative tongue size can be used to explain and predict observable interspeaker differences in vowel production.

Myocardial ischemia during mental stress: role of coronary artery disease burden and vasomotion.

BackgroundMental stress–induced myocardial ischemia (MSIMI) is associated with adverse prognosis in patients with coronary artery disease (CAD), yet the mechanisms underlying this phenomenon remain unclear. We hypothesized that compared with exercise/pharmacological stress–induced myocardial ischemia (PSIMI) that is secondary to the atherosclerotic burden of CAD, MSIMI is primarily due to vasomotor changes.Methods and ResultsPatients with angiographically documented CAD underwent 99mTc‐sestamibi myocardial perfusion imaging at rest and following both mental and physical stress testing, performed on separate days. The severity and extent of CAD were quantified using the Gensini and Sullivan scores. Peripheral arterial tonometry (Itamar Inc) was used to assess the digital microvascular tone during mental stress as a ratio of pulse wave amplitude during speech compared with baseline. Measurements were made in a discovery sample (n=225) and verified in a replication sample (n=159). In the pooled (n=384) sample, CAD severity and extent scores were not significantly different between those with and without MSIMI, whereas they were greater in those with compared with those without PSIMI (P<0.04 for all). The peripheral arterial tonometry ratio was lower in those with compared with those without MSIMI (0.55±0.36 versus 0.76±0.52, P=0.009). In a multivariable analysis, the peripheral arterial tonometry ratio was the only independent predictor of MSIMI (P=0.009), whereas angiographic severity and extent of CAD independently predicted PSIMI.ConclusionsThe degree of digital microvascular constriction, and not the angiographic burden of CAD, is associated with MSIMI. Varying causes of MSIMI compared with PSIMI may require different therapeutic interventions that require further study.

Variations in Alveolar Partial Pressure for Carbon Dioxide and Oxygen Have Additive Not Synergistic Acute Effects on Human Pulmonary Vasoconstriction

The human pulmonary vasculature constricts in response to hypercapnia and hypoxia, with important consequences for homeostasis and adaptation. One function of these responses is to direct blood flow away from poorly-ventilated regions of the lung. In humans it is not known whether the stimuli of hypercapnia and hypoxia constrict the pulmonary blood vessels independently of each other or whether they act synergistically, such that the combination of hypercapnia and hypoxia is more effective than the sum of the responses to each stimulus on its own. We independently controlled the alveolar partial pressures of carbon dioxide (Paco 2) and oxygen (Pao 2) to examine their possible interaction on human pulmonary vasoconstriction. Nine volunteers each experienced sixteen possible combinations of four levels of Paco 2 (+6, +1, −4 and −9 mmHg, relative to baseline) with four levels of Pao 2 (175, 100, 75 and 50 mmHg). During each of these sixteen protocols Doppler echocardiography was used to evaluate cardiac output and systolic tricuspid pressure gradient, an index of pulmonary vasoconstriction. The degree of constriction varied linearly with both Paco 2 and the calculated haemoglobin oxygen desaturation (1-So 2). Mixed effects modelling delivered coefficients defining the interdependence of cardiac output, systolic tricuspid pressure gradient, ventilation, Paco 2 and So 2. No interaction was observed in the effects on pulmonary vasoconstriction of carbon dioxide and oxygen (p>0.64). Direct effects of the alveolar gases on systolic tricuspid pressure gradient greatly exceeded indirect effects arising from concurrent changes in cardiac output.

Characteristics of lung function in preterm infants with varying degrees of bronchopulmonary dysplasia

To explore the characteristics of lung function in preterm infants with varying degrees of bronchopulmonary dysplasia(BPD). There were 407 infants (278 males and 129 females) were recruited from Shenzhen Children' Hospital between January 2011 and October 2012.Among them 188 term infants (term group)and 113 preterm infants (non-BPD preterm group) were selected as controls. A total of 106 BPD infants from the observation group were divided into mild(n = 48), moderate (n = 42) and severe(n = 16) sub-groups according to the definition of BPD. Infants with diseases interfering with lung function, such as congenital heart disease, congenital diaphragmatic hernia, or thoracic wall deformities, were excluded. Lung function was tested at a postmenstrual age (PMA) of 44 weeks.q test, Dunnett C test and Spearman analysis were used for statistical analysis. The age range was 17-116 d, test weight range 1.83-7.00 kg and test height range 40.0-64.0 cm.In non-BPD preterm group, the respiratory rate (RR) was higher than that in term group ((50 ± 13) vs (44 ± 10) times/min,P < 0.01) ,while the tidal volume(TV), ratio of time to peak tidal expiratory time and expiratory time (Tpef/Te) and peak expiratory flow(TPEF) were all less than those in term group ((25 ± 9) vs (29 ± 7)ml,29% ± 9% vs 33% ± 8%, (59 ± 23) vs (65 ± 25)ml/s,all P < 0.05) .Neither functional residual capacity(FRC) nor lung clearance index (LCI) had significant statistical difference between two groups ((20 ± 5) vs (19 ± 5)ml/kg, 8.4 ± 2.8 vs 8.7 ± 3.4, all P > 0.05)) . In moderate and severe BPD groups, RR ((57 ± 9), (58 ± 10) times/min) were both higher than that in non-BPD group(both P < 0.05) while RR in mild group ((53 ± 13)times/min)had no statistical significant difference with non-BPD group (P > 0.05). The values of TV and LCI in mild, moderate and severe BPD groups have no statistical significance with non-BPD group (all P > 0.05). Except for mild BPD group(24% ± 13%, (18 ± 5)ml/kg), Tpef/Te and FRC in both moderate and severe groups (20% ± 9% and 18% ± 5%, (15 ± 3)and (15 ± 4)ml/kg)were less than those in non-BPD group(all P < 0.05). Only in severe BPD group ((85 ± 11)ml/s), TPEF was higher than that in non-BPD group(P < 0.05). Correlation analysis showed that, except for LCI, all of these parameters were significantly associated with the degree of BPD(all P < 0.05). For BPD and non-BPD preterm infants, there are various changes in respiratory rhythm, lung volume, ventilation inhomogeneity, ventilatory efficiency and small airway resistance. The increases of pulmonary elastic recoil and degree of major airway constriction are obvious in moderate and severe BPD infants.

An electropalatography study of nasal-trill/lateral sequences in Spanish

Trills and laterals require relatively precise articulatory and aerodynamic settings that are at least partly incompatible with setting necessary to produce nasal stops. Historically, this incompatibility has often been resolved through assimilation, deletion, or epenthesis in within-word [n+r] and [n+l] clusters (e.g., Romance [nr] &amp;gt; [rr] or [ndr]). It is expected that similar, yet gradient effects would be observed in across-word or hetero-morphemic sequences of nasals and liquids. This study examines the production of Spanish nasal-liquid sequences using electropalatography (EPG). Linguopalatal contact data were collected from nine native speakers of Spanish (representing three dialects) producing various utterances with nasals before /r/ and /l/ (as well as before /n/). The analysis of C1 and C2 using standard EPG indices of constriction location and degree showed that nasals had a more retracted and partly deocclusivized constriction before /r/, and a lowered tongue dorsum before both /r/ and /l/. These differences, clearly reflecting anticipatory coarticulatory effects, were similar across speakers and the three dialects, which differ in the default realization of the final nasal (alveolar or velar). The findings provide evidence for articulatory incompatibility as a source of historical development of combinations of nasals and liquids.

Pharyngeal constriction in English diphthong production

This study tests the hypothesis that the acoustic difference between [a] in English diphthongs (e.g., [a] in “pie’d”) and its corresponding monophthong (e.g., [a] in “pod”) results from the same pharyngeal gesture being truncated by the following palatal glide in the diphthongal environment. Production data were collected with real-time MRI and have been analyzed using the direct image analysis (DIA) technique, which infers tissue movement by tracking pixel intensity change over time in regions of interest. Preliminary results show that (1) DIA is capable of capturing the timing and magnitude of the pharyngeal constriction gesture that produces [a], and (2) the proposed hypothesis is supported; the formation time of the pharyngeal constriction in diphthongs is generally shorter than that in like monophthongs. Further, the pharyngeal component of the diphthong is shortened in phrase-medial as opposed to phrase-final position or when followed by a voiceless as opposed to a voiced coda consonant, and the duration of this interval strongly correlates with the resulting constriction degree as predicted by the truncation analysis. [Work supported by NIH.]

Articulatory Attributes in Korean Nonassimilating Contexts

This study examined several kinematic properties of the primary articulator (the tongue dorsum) and the supplementary articulator (the jaw) in the articulation of the voiceless velar stop (/k/) within nonassimilating contexts. We examined in particular the spatiotemporal properties (constriction duration and constriction maxima) from the constriction onset to the constriction offset by analyzing a velar (/k/) followed by the coronal fricative (/s/), the coronal stop (/t/), and the labial (/p/) in across-word boundary conditions (/k#s/, /k#t/, and /k#p/). Along with these measurements, we investigated intergestural temporal coordination between C1 and C2 and the jaw articulator in relation to its coordination with the articulation of consonant sequences. The articulatory movement data was collected by means of electromagnetic midsagittal articulometry (EMMA). Four native speakers of Seoul Korean participated in the laboratory experiment. The results showed several characteristics. First, a velar (/k/) in C1 was not categorically reduced. Constriction duration and constriction degree of the velar (/k/) were similar within nonassimilating contexts (/k#s/

Scaling down constriction‐based (electrodeless) dielectrophoresis devices for trapping nanoscale bioparticles in physiological media of high‐conductivity

Selective trapping of nanoscale bioparticles (size <100 nm) is significant for the separation and high-sensitivity detection of biomarkers. Dielectrophoresis is capable of highly selective trapping of bioparticles based on their characteristic frequency response. However, the trapping forces fall steeply with particle size, especially within physiological media of high-conductivity where the trapping can be dissipated by electrothermal (ET) flow due to localized Joule heating. Herein, we investigate the influence of device scaling within the electrodeless insulator dielectrophoresis geometry through the application of highly constricted channels of successively smaller channel depth, on the net balance of dielectrophoretic trapping force versus ET drag force on bioparticles. While higher degrees of constriction enable dielectrophoretic trapping of successively smaller bioparticles within a short time, the ETflow due to enhanced Joule heating within media of high conductivity can cause a significant dissipation of bioparticle trapping. This dissipative drag force can be reduced through lowering the depth of the highly constricted channels to submicron sizes, which substantially reduces the degree of Joule heating, thereby enhancing the range of voltages and media conductivities that can be applied toward rapid dielectrophoretic concentration enrichment of silica nanoparticles (∼50 nm) and streptavidin protein biomolecules (∼5 nm). We envision the application of these methodologies toward nanofabrication, optofluidics, biomarker discovery, and early disease diagnostics.

How Do Cord Compressions Affect the Umbilical Venous Flow Resistance? An In Vitro Investigation of the Biomechanical Mechanisms.

Umbilical vessels, that provide blood oxygenation and fetal nourishment in utero, are encased and protected against external forces by the umbilical cord. The biomechanics of this peculiar structure has not been deeply investigated so far. The purpose of this study is to investigate the hydraulic behaviour of human umbilical veins (UV) and its changes in presence of an external cord compression. Five umbilical cords were subjected to in vitro tests. UV was accurately cannulated and connected to a perfusion circuit, while the cord was subjected to an external compression. Pressure drops across UV were measured for various venous flow rates and various degrees of cord constriction. Compressive forces were measured, too. The UV hydraulic resistances measured in unloaded cords (0.029±0.016mmHgmincm-1L-1) correspond to placenta-abdomen pressure drops well consistent with in utero measurements. As expected, at fixed flow rate, flow resistance augments when cord is compressed. Interestingly, resistance does not substantially change until a 30-50% cord thickness reduction, whereas slightly larger constriction cause a steep increase. Compressive forces becomes critical for values above 0.5-2N, depending on the length of cord compression and on considered specimen. Moreover, at high cord constriction, hydraulic behaviour of UV is very peculiar. Namely, the slope of the pressure-flow relationship decreases at increasing flow rates and, in few cases, a surprising reduction of pressure drop was even observed. The biomechanical behaviour of the umbilical cord during compression is very complex, with high non-linearity of venous hydraulic behaviour.

Dialectal Differences in Spanish Voiced Obstruent Allophony: Costa Rican versus Iberian Spanish

The Spanish voiced obstruents /b d g/ are traditionally described as having each two allophones: stop and fricative (approximant) in complementary distribution. Several researchers have noted that some Central American and Highland Colombian varieties deviate from the general allophonic distribution in showing a preference for stop realizations in all contexts, except for the intervocalic position. In this paper we report on a large-scale acoustic investigation of /b d g/ in postconsonantal (after a liquid, sibilant or glide) and postvocalic (after /a/) contexts in Costa Rica Spanish, establishing a comparison with the variety of Madrid, Spain, which we take as representative of a variety with the general pattern of allophony. Our study, based on a continuous measurement of intensity, confirms previous descriptions in that Costa Rica Spanish does indeed show a different pattern of allophony from that found in the Madrid variety. The analysis shows that in Costa Rica Spanish postconsonantal realizations of /b/ and /d/ are very different from postvocalic ones, with a clear separation in the degree of constriction between these two contexts. In Madrid, on the other hand, we find a continuum of constriction degrees, depending on the nature of the specific preceding segment, and without a clear separation between postvocalic and postconsonantal realizations. The question that naturally arises is that of the historical connection between these two patterns of allophony, for which we offer some speculation, based in historical parallels and comparison with other varieties.

Abstract 18514: The Degree of Microvascular Constriction During Mental Stress Predicts the Development of Mental Stress-Induced Myocardial Ischemia

Introduction: Mental stress-induced myocardial ischemia (MSI) has been linked to a higher rate of fatal and non-fatal cardiac events in patients with CAD, independent of traditional cardiovascular risk models. Coronary vascular constriction with mental stress is a potential mechanism of MSI that may be reflected as constriction in the peripheral circulation. Moreover, peripheral arterial constriction may itself contribute to MSI by increasing afterload. Hypothesis: We hypothesized that a more pronounced microvascular constrictor response to mental stress will be predictive of development of MSI. Methods: Patients with stable CAD (n=116) underwent a standardized mental stress test using a public speaking task. Myocardial perfusion imaging with 99m-Tc-sestamibi was used for rest and stress images. MSI was defined as a summed difference score of ≥4, based on the difference between summed stress and rest perfusion scores. Peripheral arterial tonometry (PAT) was used to assess peripheral microvascular function during rest and mental stress. The PAT response was calculated as a ratio of the lowest pulse wave amplitude during the speaking task to the final three minutes of pulse wave amplitude during baseline rest. Univariate and multivariate logistic regression models were used to assess the association between PAT response and MSI. Models were adjusted for established CAD risk factors, and medications. Results: Patients with MSI (n=16, 14%) had a significantly lower PAT ratio than those without MSI (0.49 ±0.26 vs. 0.72± 0.34, p=0.01). Furthermore, the PAT response during mental stress was an independent predictor of the development of MSI, even after adjusting for aforementioned covariates (p=0.01). The peak rate-pressure product and diastolic BP during speech were similar in those with or without MSI (13580±4873 vs. 12947±2914, p=0.5; and 101±14 vs. 99±12, p=0.6, respectively). Systolic BP, diastolic BP, and heart rate changes from rest to speech were similar in those with and without MSI. Conclusion: The degree of peripheral microvascular constriction in response to mental stress predicts the risk of developing MSI in patients with stable CAD. Whether the PAT response during mental stress portends a worse long term prognosis needs to be investigated.