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Pulse wave imaging as an indicator of arterial stiffness in patients affected with periodontitis

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Universitat de Barcelona. Facultat d'Odontologia

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[eng]  In this thesis, the relationship between periodontitis and arterial stiffness was assessed by a new technique known as Pulse Wave Imaging (PWI). PWI is a non-invasive ultrasound-based technique developed by members of our team, and is intended to overcome some limitations of classic methods for assessing elasticity.  PWI can be used to determine Pulse Wave Velocity (PWV) and assess homogeneity in the transmission of the wave (R2).  In addition, a feasibility study was conducted to determine Pulse Pressure (PP) at a central artery through PWI. 
A cross-sectional study including a sample of 80 volunteers was designed excluding participants with a history of cardiovascular disease, apart from hypertension. 40 subjects presented with moderate to severe periodontitis, defined as a minimum of two teeth per quadrant with probing depths (PD)>5mm, concomitant clinical attachment loss (CAL)>3mm and bleeding on probing (BoP) in more than 30% of the sites. The control group was comprised of gender- and age-matched (within a 5 year interval) periodontally healthy subjects with absence of PD>4mm and interproximal CAL>2mm. All patients received a full periodontal exam and the elasticity of right and left carotid arteries was assessed to determine the outcome variables PWV and R2.  As PWI is a new technique, two thresholds (A and B) were used to analyze the results. Threshold A was generic while Threshold B was individualized. To explore differences within the groups, the PWV and R2 results from the paired samples were compared using the Wilcoxon Signed Rank Test. Univariate and multivariate analyses were carried out to assess the association between PWV/R2 and other explicative variables.
For the PP evaluation, a subsample of patients in whom the aorta was easily visible with ultrasounds was chosen. The patients were classified by their brachial blood pressure as normotensive, pre- or hypertensive. PP was then calculated in three locations of the arterial tree – brachial, radial and aortic arteries. The PP results were analyzed through the two-way ANOVA and the Bonferroni correction. 
The application of Thresholds A and B resulted in 30 and 33 control-patient pairs, respectively. Results from Threshold A did not reveal statistically significant differences between the groups in regards to PWV (median of 2.37m/sec for periodontitis patients vs. 2.64m/sec in controls, p=0.74) or R2 (0.74 vs. 0.71, p=0.81). The univariate analysis revealed negative non-significant associations between the outcome variable R2 and the explicative variables: presence of periodontitis, variables related to periodontitis, age, and systolic/diastolic blood pressures.  The multiple regression analysis revealed a significant association between R2 and gender (p=0.04). The results from Threshold B differed, revealing that patients with periodontitis presented significantly lower uniformity in wave propagation (R2) than controls (p=0.01), while PWV results were not statistically different between the two groups. Univariate analysis showed a significant negative association between R2 and periodontitis, its associated variables, and smoking. Periodontitis remained statistically associated with R2 in the multivariable analysis. When studying the PP results, significantly higher values were observed in the aortas of hypertensive patients compared to the values obtained in the radial and brachial arteries, regardless of the patients’ blood pressure status. 
In summary, a lower degree of uniformity was observed in the transmission of the pulse wave in the carotid artery in a sample of periodontal patients with no history of cardiovascular disease. This suggests an association between periodontitis and arterial stiffness and supports the body of evidence indicating an association between periodontitis and atherosclerosis.  Notably, the results from applying Threshold A and B were quite different, emphasizing the importance of using personalized thresholds. The PP analysis concluded that it is feasible to use non-invasive methods to determine PP in high-caliber central arteries such as the aorta.

# metadata.dc.description.abstract[].value
[spa]  Se investigó la relación entre el estado periodontal y la rigidez arterial mediante Imagen de Onda de Pulso (PWI). PWI es una técnica no invasiva basada en el uso de ultrasonidos, la cual ha sido recientemente desarrollada por miembros de nuestro equipo y que pretende superar algunas de las limitaciones de las técnicas clásicamente utilizadas para valorar la elasticidad arterial.  En este trabajo, PWI se utilizó para calcular la velocidad de la onda del pulso (PWV) y valorar la homogeneidad de transmisión de la misma (R2). A su vez, se analizó la factibilidad del cálculo de la Presión del Pulso (PP) en una arteria central mediante el uso de la misma técnica.
Se analizó transversalmente una muestra de 80 individuos, pareada respecto a género y edad (±5 años). Cuarenta pacientes presentaban periodontitis moderada-severa, y el resto fueron clasificados como periodontalmente sanos. Pacientes con antecedentes de enfermedad cardiovascular (excepto hipertensión) fueron excluidos. Los resultados obtenidos al determinar la PWI en la carótida (PWV y R2) fueron analizados mediante el uso de dos umbrales diferentes, uno genérico y otro personalizado, mientras que la PP fue determinada en las arterias aorta, braquial y radial mediante el uso de tres métodos distintos. 
Los resultados muestran menor uniformidad en la propagación de la onda (R2) en los pacientes periodontales tras aplicar el umbral personalizado (p=.01). El análisis univariable reveló una asociación significativa negativa entre R2 y periodontitis, sus variables asociadas y tabaco. Esta asociación se mantuvo en el análisis multivariable entre R2 y periodontitis. Por otro lado, no se observaron diferencias estadísticamente significativas para las variables PWV y R2 al aplicar el umbral genérico o respecto a PWV tras aplicar el umbral individualizado. En referencia al análisis de la PP, se confirma la factibilidad en su obtención en arterias centrales de pacientes hipertensos. 
En conclusión, se encontró una asociación entre periodontitis y una alteración funcional de las arterias, resultando en una disminución de su elasticidad. Respecto al análisis de datos realizado, cabe destacar el impacto en los resultados al considerar umbrales genéricos vs. personalizados. PWI se perfila como un método innovador en el análisis de la elasticidad arterial en pacientes con factores de riesgo arteriosclerótico y sin historia de eventos CV mayores.

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Tesis Doctorals - Facultat – Odontologia

# metadata.dc.title[].value
Pulse wave imaging as an indicator of arterial stiffness in patients affected with periodontitis