The suppression of spiral waves and spatiotemporal chaos in cardiac tissue was studied based on cardiac model. We proposed two strategies of suppressing spiral wave and spatiotemporal chaos. One was to elevate the extracellular potassium ion concentration suddenly. This method can effectively suppress spiral waves and spatiotemporal chaos when the elevated extracellular potassium ion concentration reaches a critical value, especially when the spiral wave pinned to defects also can be suppressed. The other was to let the extracellular potassium ion concentration varies periodically while the amplitude of concentration was limited. We found that the method could effectively suppress spiral waves and spatiotemporal chaos when the related parameters were properly chosen. But it can not suppress the pinned spiral waves. And the control mechanism is discussed in this paper.
Action Potentials ; physiology ; Arrhythmias, Cardiac ; complications ; physiopathology ; Computer Simulation ; Heart ; physiology ; Humans ; Models, Cardiovascular ; Potassium ; metabolism

OBJECTIVE: To evaluate the application of surgical strategies for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) involving the C ₂ segment. METHODS: The literature about the surgery for cervical OPLL involving C ₂ segment was reviewed, and the indications, advantages, and disadvantages of surgery were summarized. RESULTS: For cervical OPLL involving the C ₂ segments, laminectomy is suitable for patients with OPLL involving multiple segments, often combined with screw fixation, and has the advantages of adequate decompression and restoration of cervical curvature, with the disadvantages of loss of cervical fixed segmental mobility. Canal-expansive laminoplasty is suitable for patients with positive K-line and has the advantages of simple operation and preservation of cervical segmental mobility, and the disadvantages include progression of ossification, axial symptoms, and fracture of the portal axis. Dome-like laminoplasty is suitable for patients without kyphosis/cervical instability and with negative R-line, and can reduce the occurrence of axial symptoms, with the disadvantage of limited decompression. The Shelter technique is suitable for patients with single/double segments and canal encroachment >50% and allows for direct decompression, but is technically demanding and involves risk of dural tear and nerve injury. Double-dome laminoplasty is suitable for patients without kyphosis/cervical instability. Its advantages are the reduction of damage to the cervical semispinal muscles and attachment points and maintenance of cervical curvature, but there is progress in postoperative ossification. CONCLUSION OPLL involving the C ₂ segment is a complex subtype of cervical OPLL, which is mainly treated through posterior surgery. However, the degree of spinal cord floatation is limited, and with the progress of ossification, the long-term effectiveness is poor. More research is needed to address the etiology of OPLL and to establish a systematic treatment strategy for cervical OPLL involving the C ₂ segment.
Humans ; Longitudinal Ligaments/surgery* ; Ossification of Posterior Longitudinal Ligament/surgery* ; Treatment Outcome ; Osteogenesis ; Decompression, Surgical/methods* ; Cervical Vertebrae/surgery* ; Laminoplasty/methods* ; Kyphosis/surgery* ; Retrospective Studies