Objectives: The analysis of wall strain opens new perspectives in the prediction of abdominal aortic aneurysm (AAA) rupture. This study investigates the capability of four‐dimensional ultrasound (4D US) to detect and characterize changes in wall strain in the same patients during follow‐up observations.Methods: Eighteen patients were examined by 64 4D US scans during a median follow‐up period of 24.5 months. After performing the 4D US and manual aneurysm segmentation, kinematic analysis was performed using a customized interface and evaluation of the mean and peak circumferential strain, as well as spatial heterogeneity.Results: All aneurysms showed a continuous diameter growth with a mean rate of 4% per year (P < .001). The mean circumferential strain (MCS) tends to increase from a median 0.89% by 10.49% per year in follow‐up independent of the aneurysm diameter (P = .063). The subgroup analysis reveals a cohort with increasing MCS and decreasing spatial heterogeneity, as well as a cohort with nonincreasing MCS and increasing spatial heterogeneity (P < .05).Conclusions: The 4D US is able to register the strain changes in AAA follow‐up. The MCS tends to increase during the observation time in the entire cohort, but the changes were independent of the maximum aneurysm diameter. The kinematic parameters allow the entire AAA cohort to differentiate into two subgroups and provide additional information about the pathologic behavior of the aneurysm wall.

Abdominal aortic aneurysms are a degenerative disease of the aorta associated with high mortality. To date, in vivo information to characterize the individual elastic properties of the aneurysm wall in terms of rupture risk is lacking. We have used time-resolved 3D ultrasound strain imaging to calculate spatially resolved in-plane strain distributions characterized by mean and local maximum strains, as well as indices of local variations in strains. Likewise, we here present a method to generate averaged models from multiple segmentations. Strains were then calculated for single segmentations and averaged models. After registration with aneurysm geometries based on CT-A imaging, local strains were divided into two groups with and without calcifications and compared. Geometry comparison from both imaging modalities showed good agreement with a root mean squared error of 1.22 ± 0.15 mm and Hausdorff Distance of 5.45 ± 1.56 mm (mean ± sd, respectively). Using averaged models, circumferential strains in areas with calcifications were 23.2 ± 11.7% (mean ± sd) smaller and significantly distinguishable at the 5% level from areas without calcifications. For single segmentations, this was possible only in 50% of cases. The areas without calcifications showed greater heterogeneity, larger maximum strains, and smaller strain ratios when computed by use of the averaged models. Using these averaged models, reliable conclusions can be made about the local elastic properties of individual aneurysm (and long-term observations of their change), rather than just group comparisons. This is an important prerequisite for clinical application and provides qualitatively new information about the change of an abdominal aortic aneurysm in the course of disease progression compared to the diameter criterion.

Background: Major surgery is associated with significant morbidity and a reduced quality of life, particularly among older adults and individuals with frailty and impaired functional capacity. Multimodal prehabilitation can enhance functional recovery after surgery and reduce postoperative complications. Digital prehabilitation has the potential to be a resource-sparing and patient-empowering tool that improves patients’ preoperative status; however, little remains known regarding their safety and accuracy as medical devices. Objective: This study aims to test the accuracy and validity of a new software in comparison to the gold-standard electrocardiogram (ECG)-based heart rate measurement. Methods: The PROTEGO MAXIMA trial was a prospective interventional pilot trial assessing the validity, accuracy, and safety of an app-based exercise program. The Prehab App calculates a personalized, risk-stratified aerobic interval training plan based on individual risk factors and utilizes wearables to monitor heart rate. Healthy students and patients undergoing major surgery were enrolled. A structured risk assessment was conducted, followed by a 6-minute walking test and a 37-minute supervised interval session. During the exercise, patients wore app-linked wearables for heart rate and distance measurements, which were compared with standard ECG and treadmill measurements. Safety, accuracy, and usability assessments included testing alarm signals, while the occurrence of adverse events served as the primary and secondary outcome measures. Results: A total of 75 participants were included. The mean heart rate differences between wearables and standard ECG were ≤5 bpm (beats per minute) with a mean absolute percentage error of ≤5%. Regression analysis revealed a significant impact of the BMI (odds ratio 0.90, 95% CI 0.82-0.98, P=.02) and Timed Up and Go Test score (odds ratio 0.12, 95% CI 0.03-0.55, P=.006) on the accuracy of heart rate measurement; 29 (39%) patients experienced adverse events: pain (5/12, 42%), ECG electrode–related skin irritations (2/42, 17%), dizziness (2/42, 17%), shortness of breath (2/42, 17%), and fatigue (1/42, 8%). No cardiovascular or serious adverse events were reported, and no serious device deficiency was detected. There were no indications of clinically meaningful overexertion based on laboratory values measured before and after the 6-minute walking test and exercise. The differences in means and ranges were as follows: lactate (mmol/l), mean 0.04 (range –3 to 6; P=.47); creatinine kinase (U/l), mean 12 (range –7 to 43; P<.001); and sodium (mmol/l), mean –2 (range –11 to 12; P<.001). Conclusions: The interventional trial demonstrated the high safety of the exercise program and the accuracy of heart rate measurements using commercial wearables in patients before major surgery, paving the way for potential remote implementation in the future. Trial Registration: German Clinical Trials Register DRKS00026985; https://drks.de/search/en/trial/DRKS00026985 and European Database on Medical Devices (EUDAMED) CIV-21-07-0307311. International Registered Report Identifier (IRRID): RR2-10.1136/bmjopen-2022-069394

Objectives The four‐dimensional ultrasound (4D‐US) enables imaging of the aortic segment and simultaneous determination of the wall expansion. The method shows a high spatial and temporal resolution, but its in vivo reliability is so far unknown for low‐measure values. The present study determines the intraobserver repeatability and interobserver reproducibility of 4D‐US in the atherosclerotic and non‐atherosclerotic infrarenal aorta. Methods In all, 22 patients with non‐aneurysmal aorta were examined by an experienced examiner and a medical student. After registration of 4D images, both the examiners marked the aortic wall manually before the commercially implemented speckle tracking algorithm was applied. The cyclic changes of the aortic diameter and circumferential strain were determined with the help of custom‐made software. The reliability of 4D‐US was tested by the intraclass correlation coefficient (ICC). Results The 4D‐US measurements showed very good reliability for the maximum aortic diameter and the circumferential strain for all patients and for the non‐atherosclerotic aortae (ICC >0.7), but low reliability for circumferential strain in calcified aortae (ICC = 0.29). The observer‐ and masking‐related variances for both maximum diameter and circumferential strain were close to zero. Conclusions Despite the low‐measured values, the high spatial and temporal resolution of the 4D‐US enables a reliable evaluation of cyclic diameter changes and circumferential strain in non‐aneurysmal aortae independent from the observer experience but with some limitations for calcified aortae. The 4D‐US opens up a new perspective with regard to noninvasive, in vivo assessment of kinematic properties of the vessel wall in the abdominal aorta.