[Detection algorithm of paroxysmal atrial fibrillation with sparse coding based on Riemannian manifold]

In order to solve the problem that the early onset of paroxysmal atrial fibrillation is very short and difficult to detect, a detection algorithm based on sparse coding of Riemannian manifolds is proposed. The proposed method takes into account that the nonlinear manifold geometry is closer to the real feature space structure, and the computational covariance matrix is used to characterize the heart rate variability (RR interval variation), so that the data is in the Riemannian manifold space. Sparse coding is applied to the manifold, and each covariance matrix is represented as a sparse linear combination of Riemann dictionary atoms. The sparse reconstruction loss is defined by the affine invariant Riemannian metric, and the Riemann dictionary is learned by iterative method. Compared with the existing methods, this method used shorter heart rate variability signal, the calculation was simple and had no dependence on the parameters, and the better prediction accuracy was obtained. The final classification on MIT-BIH AF database resulted in a sensitivity of 99.34%, a specificity of 95.41% and an accuracy of 97.45%. At the same time, a specificity of 95.18% was realized in MIT-BIH NSR database. The high precision paroxysmal atrial fibrillation detection algorithm proposed in this paper has a potential application prospect in the long-term monitoring of wearable devices.

[Comparison of the effects of two cephalomedullary nails (zimmer natural nail and proximal femoral nail antirotation) in treatment of elderly intertrochan teric fractures]

OBJECTIVE

To explore the effect of cephalomedullary nails for elderly intertrochanteric fractures: proximal femoral nail antirotation (PFNA) versus zimmer natural nail (ZNN) to provide the data support for clinical perioperative management.

METHODS

A retrospective study was used to analyze the clinical data of elderly intertrochanteric fractures cases which were treated with PFNA or ZNN fixation from May 2016 to May 2017. In the study, 59 cases were followed up completely, in which 28 cases accepted PFNA, and the other 31 cases accepted ZNN. The operation time, amount of bleeding, fracture healing time, postoperative complication, postoperative radiographic measurement (tip apex distance, TAD) and the last follow-up of hip function score were analyzed.

RESULTS

The patients were followed up for 6 to 19 months, with an average (10.8±4.0) months. In PFNA group, the operation time was (62.7±14.2) min, the amount of bleeding was (56.8±20.6) mL, the fracture healing time was (4.6±0.8) months, the postoperative complication was 3.6%, the TAD was (17.7±5.5) mm, and the last follow-up hip function score was 91.8±3.6. In ZNN group, the operation time was (73.6±18.3) min, the amount of bleeding was (68.7±31.6) mL, the fracture healing time was (4.5±0.7) months, the postoperative complication was 3.2%, the TAD was (16.5±4.7) mm, and the last follow-up hip function score was 92.2±3.8. The two groups of comparative experiments were carried out, the operation time of the PFNA group was less than that of the ZNN group (P<0.05). There was no significant difference in the amount of bleeding, fracture healing time, postoperative complication, TAD, postoperative hip score between the two groups (P>0.05).

CONCLUSION

Although group ZNN had significant longer operation time than group PFNA, both implants were useful tools in the treatment of elderly intertrochanteric fractures. The operation of PFNA was simpler,while the design of the anterior bow of ZNN might be more suitable for the patients with a large femoral anterior bow.