Critical Points and the Upper Limit of Vulnerability for Defibrillation

2008 ◽  
pp. 165-187
Author(s):  
Raymond E. Ideker ◽  
Derek J. Dosdall
Keyword(s):  
Critical Points ◽  
Upper Limit ◽  
Upper Limit Of Vulnerability

scholarly journals How Hyperpolarization and the Recovery of Excitability Affect Propagation through a Virtual Anode in the Heart

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Nicholas P. Charteris ◽  
Bradley J. Roth
Keyword(s):  
Wave Front ◽  
Time Constant ◽  
Computer Model ◽  
Propagation Speed ◽  
One Dimensional ◽  
Upper Limit ◽  
Rapid Propagation ◽  
Upper Limit Of Vulnerability ◽  
Key Factor ◽  
Sodium Inactivation

Researchers have suggested that the fate of a shock-induced wave front at the edge of a “virtual anode” (a region hyperpolarized by the shock) is a key factor determining success or failure during defibrillation of the heart. In this paper, we use a simple one-dimensional computer model to examine propagation speed through a hyperpolarized region. Our goal is to test the hypothesis that rapid propagation through a virtual anode can cause failure of propagation at the edge of the virtual anode. The calculations support this hypothesis and suggest that the time constant of the sodium inactivation gate is an important parameter. These results may be significant in understanding the mechanism of the upper limit of vulnerability.

Effects of n-3 polyunsaturated fatty acid on upper limit of vulnerability shocks

2006 ◽  
Vol 107 (3) ◽  
pp. 299-302 ◽  
Author(s):  
Nipon Chattipakorn ◽  
Krekwit Shinlapawittayatorn ◽  
Rattapong Sungnoon ◽  
Siriporn C. Chattipakorn
Keyword(s):  
Fatty Acid ◽  
Polyunsaturated Fatty Acid ◽  
Upper Limit ◽  
Upper Limit Of Vulnerability

Measurement of the Upper Limit of Vulnerability during Defibrillator Implantation can Substitute Defibrillation Threshold Measurement

1998 ◽  
Vol 21 (3) ◽  
pp. 151-160 ◽  
Author(s):  
R. Bessho ◽  
S. Tanaka
Keyword(s):  
High Energy ◽  
Amiodarone Therapy ◽  
Strongly Correlated ◽  
Special Equipment ◽  
Icd Implantation ◽  
Energy Current ◽  
Upper Limit ◽  
Upper Limit Of Vulnerability ◽  
Myocardial Injuries ◽  
Threshold Measurement

We investigated whether defibrillation thresholds (DFTs) could be measured more safely during defibrillator implantation by measuring the upper limit of vulnerability (ULV) without using any special equipment. Nonthoracotomy ICD implantation with endocardial leads was performed in 13 patients, and through the use of the ICD function itself, ULV and DFT were measured using the delayed four-episode up-down algorithm. Myocardial injures caused by high-energy current were assessed by electrocardiograms and serial CPK-MB. ULV was confirmed in all cases, and it strongly correlated with DFT. The average ULV was 5.9 ± 3.3J, while the average DFT was 7.9 ± 4.3J (r = 0.89, p < 0.0001, DFT = 1.20+1.14x ULV). The average ULV was thus significantly lower (p < 0.01). Although six patients were on amiodarone therapy, the strong correlation between ULV and DFT was also maintained (r = 0,97), p < 0.01) in these patients. In all cases, the CPK-MB failed to increase, and no myocardial injuries were detectable on electrocardiograms. We confirmed that ULV could be easily and safety measured during ICD implantation, and that ULV could be used instead of DFT.

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