Ultrasonographic assessment of abdominal aortic elasticity in hypertensive dogs

The echocardiographic pulmonary to left atrial ratio: A noninvasive variable for the hemodynamic classification of pulmonary hypertension in dogs

BACKGROUND

Hemodynamic classification of pulmonary hypertension (PH) has important clinical implications. However, only a few echocardiographic variables have been used to hemodynamically classify PH in dogs.

OBJECTIVE

To evaluate the echocardiographic pulmonary to left atrial ratio index (ePLAR) in dogs with PH.

ANIMALS

Forty-six dogs with intermediate to high probability of PH.

METHODS

Cross-sectional study. Variables were compared between dogs with precapillary PH [PrePH (n = 24)] vs postcapillary PH [PostPH (n = 22)], and with combined PH [CombPH (n = 14)] vs isolated PH [IsoPH (n = 8)] using the t-, Mann-Whitney, Pearson's Chi, or Fisher's exact test. The receiver operating characteristic curve and Youden index were used to identify the optimal ePLAR cutoff value to differentiate among the groups, intraclass correlation coefficients (ICC) were used to determine the reliability of measurements.

RESULTS

The mean (SD) ePLAR of the PrePH was higher than that of the PostPH group [0.36 (0.13) vs 0.26 (0.09), respectively; P = .005]. The median (interquartile range) ePLAR of the CombPH was higher than that of the IsoPH subgroup [0.29 (0.24-0.38), vs 0.20 (0.16-0.23), respectively; P = .001]. The best cutoff value of ePLAR for identifying IsoPH was <0.245 [AUC at cutoff point = 0.86; sensitivity (95% confidence interval [CI]) = 0.71 (0.47-0.95); specificity (95% CI) = 1 (0.76-1)]. The ICC analysis indicated a high degree of reliability.

CONCLUSIONS AND CLINICAL IMPORTANCE

ePLAR can be considered a valid noninvasive variable to hemodynamically classify PH in dogs with an intermediate to high probability of PH. Assessment of ePLAR can be useful in the therapeutic management of PH in dogs.

Thoracic and abdominal aortic alterations in dogs affected with systemic hypertension

Aortic remodeling is the consequence of untreated systemic hypertension along with aortic dilatation as a marker for target organ damage in human literature. Therefore, the present study was planned to detect the changes in aorta at the level of aortic root via echocardiography, thoracic descending aorta via radiography and abdominal aorta via ultrasonography in healthy (n = 46), diseased normotensive (n = 20) and systemically hypertensive dogs (n = 60). The aortic root dimensions were measured at the level of aortic annulus, sinus of valsalva, sino-tubular junction and proximal ascending aorta via left ventricular outflow tract view of echocardiography. The thoracic descending aorta was subjectively assessed for any disparity in size and shape of aorta via lateral and dorso-ventral view of chest radiography. The abdominal aorta was assessed via left and right paralumbar window for calculating the aortic elasticity along with aortic and caudal venacaval dimensions to calculate the aortic-caval ratio. The aortic root measurements were dilated (p < 0.001) in systemically hypertensive dogs with a positive correlation (p < 0.001) with systolic blood pressure (BP). Thoracic descending aorta was also (p < 0.05) altered in the size and shape (undulation) of systemically hypertensive dogs. Abdominal aorta was markedly stiffened with reduced elasticity (p < 0.05) along with dilatation (p < 0.01) in hypertensive dogs. Also, there was a positive correlation (p < 0.001) of aortic diameters and aortic-caval ratio and negative correlation (p < 0.001) of aortic elasticity with systolic BP. Therefore, it was concluded that aorta could be considered as an important target organ damage of systemic hypertension in dogs.

Aortic Stiffness: A Major Risk Factor for Multimorbidity in the Elderly

Multimorbidity, the coexistence of multiple health conditions in an individual, has emerged as one of the greatest challenges facing health services, and this crisis is partly driven by the aging population. Aging is associated with increased aortic stiffness (AoStiff), which in turn is linked with several morbidities frequently affecting and having disastrous consequences for the elderly. These include hypertension, ischemic heart disease, heart failure, atrial fibrillation, chronic kidney disease, anemia, ischemic stroke, and dementia. Two or more of these disorders (multimorbidity) often coexist in the same elderly patient and the specific multimorbidity pattern depends on several factors including sex, ethnicity, common morbidity routes, morbidity interactions, and genomics. Regular exercise, salt restriction, statins in patients at high atherosclerotic risk, and stringent blood pressure control are interventions that delay progression of AoStiff and most likely decrease multimorbidity in the elderly.

The Progress of Advanced Ultrasonography in Assessing Aortic Stiffness and the Application Discrepancy between Humans and Rodents

Aortic stiffening is a fundamental pathological alteration of atherosclerosis and other various aging-associated vascular diseases, and it is also an independent risk factor of cardiovascular morbidity and mortality. Ultrasonography is a critical non-invasive method widely used in assessing aortic structure, function, and hemodynamics in humans, playing a crucial role in predicting the pathogenesis and adverse outcomes of vascular diseases. However, its applications in rodent models remain relatively limited, hindering the progress of the research. Here, we summarized the progress of the advanced ultrasonographic techniques applied in evaluating aortic stiffness. With multiple illustrative images, we mainly characterized various ultrasound techniques in assessing aortic stiffness based on the alterations of aortic structure, hemodynamics, and tissue motion. We also discussed the discrepancy of their applications in humans and rodents and explored the potential optimized strategies in the experimental research with animal models. This updated information would help to better understand the nature of ultrasound techniques and provide a valuable prospect for their applications in assessing aortic stiffness in basic science research, particularly with small animals.

Ultrasonographic assessment of abdominal aortic elasticity in hypertensive dogs

Background

Systemic hypertension (SH) is a persistent and pathological increase in arterial blood pressure (BP). Chronic SH leads to an increase in aortic (Ao) stiffness, and measuring Ao elasticity is useful for estimating Ao stiffness in humans. Currently, no literature in veterinary medicine describes noninvasive assessment of abdominal Ao elasticity in dogs with SH.

Objective

Compare ultrasonographic‐derived abdominal Ao strain (AoSt) between hypertensive (HT) and normotensive (NT) dogs.

Animals

Fifty privately‐owned dogs with clinical signs, conditions, or both potentially associated with SH.

Methods

Prospective observational case‐control study. Aortic stiffness was estimated by calculating AoSt as follows: AoSt = ([AoDs − AoDd]/AoDd) × 100, where AoDs and AoDd are the Ao diameter in systole and in diastole, respectively. Aortic stiffness was calculated from 2 different Ao transverse sections, the first caudal to the left renal artery (K_AoSt), and the second cranial to the external iliac arteries (I_AoSt).

Results

Thirty‐two dogs were included in the HT group and 18 in the NT group. Both K_AoSt and I_AoSt in HT dogs were significantly lower (P < .05) than in NT dogs (7.4 ± SD 3.6) vs 10.3 (±3.8) and 5.7 (interquartile range [IQR], 3.9‐7.5) vs 8.1 (IQR, 7‐10.3), respectively. Only K_AoSt was significantly influenced by age.

Conclusions and Clinical Importance

Ultrasonographic Ao elasticity assessment was feasible to compare HT and NT dogs. Results indicated that K_AoSt and I_AoSt indices can be used to assess SH‐related Ao stiffness, especially when indirect BP measurements are inconsistent or inaccurate. Additional studies to assess the AoSt in healthy dogs of various ages are needed.