Effects of Transient Myocardial Ischemia on the Ventricular Defibrillation Threshold

Anastasiou-Nana, Maria; Tsagalou, Eleftheria P.; Charitos, Christos; Siafakas, Kostantinos X; Drakos, Stavros; Terrovitis, John; Ntalianis, Argirios; A, Doufas; Mavrikakis, John; Nanas, John N.

doi:10.1111/j.1540-8159.2005.09303.x

Cited by 19 publications

(10 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When compared with 60 Hz induction, VF secondary to ischemia increased defibrillation threshold three-to four-fold, depending on the site of coronary occlusion (i.e., LAD or circumflex artery) and, presumably, the mass of myocardium at risk. A similar increase in defibrillation threshold was observed after 2 mins of LAD occlusion followed by epicardial defibrillation (23). The differences in defibrillation energy requirements between these studies and our countershock outcome data are likely due to the fact that the first shock dose of 200 J likely exceeded defibrillation threshold in most animals in both groups.…”

Section: Discussionsupporting

confidence: 82%

Is all ventricular fibrillation the same? A comparison of ischemically induced with electrically induced ventricular fibrillation in a porcine cardiac arrest and resuscitation model*

Niemann¹,

Rosborough²,

Youngquist³

et al. 2007

Critical Care Medicine

View full text Add to dashboard Cite

Resuscitation from ischemic ventricular fibrillation is more difficult than electrical ventricular fibrillation and is characterized by greater time to restoration of spontaneous circulation, frequent refibrillation, greater number of countershocks, higher epinephrine dose during resuscitation efforts, profound cardiac dysfunction, and a short-term survival rate approaching clinical experience. Ischemically induced ventricular fibrillation is a more clinically relevant model for the evaluation of resuscitation interventions.

show abstract

Section: Discussionsupporting

confidence: 82%

Is all ventricular fibrillation the same? A comparison of ischemically induced with electrically induced ventricular fibrillation in a porcine cardiac arrest and resuscitation model*

Niemann¹,

Rosborough²,

Youngquist³

et al. 2007

Critical Care Medicine

View full text Add to dashboard Cite

show abstract

“…This is not surprising: Defibrillation testing is performed on sedated patients after clinical variables have been optimized. In contrast, spontaneous VT/VF occur in a less "controlled" environment that may include variations in multiple variables known to reduce defibrillation efficacy: autonomic tone, 71 ischemia, 72,73 hyperkalemia, 74 exacerbation of heart failure, drugs prescribed in follow-up (see following), or progression of cardiac disease. 75 DFTs are also higher in the upright than supine The percent of patients with a successful maximum output shock is plotted on the ordinate.…”

Section: Prediction Of Shock Success For Spontaneous Arrhythmias In Tmentioning

confidence: 99%

The Dilemma of ICD Implant Testing

Swerdlow

Russo

DeGroot

2007

Pacing Clinical Electrophis

130

112

View full text Add to dashboard Cite

Ventricular fibrillation (VF) has been induced at implantable cardioverter defibrillator (ICD) implant to ensure reliable sensing, detection, and defibrillation. Despite its risks, the value was self-evident for early ICDs: failure of defibrillation was common, recipients had a high risk of ventricular tachycardia (VT) or VF, and the only therapy for rapid VT or VF was a shock. Today, failure of defibrillation is rare, the risk of VT/VF is lower in some recipients, antitachycardia pacing is applied for fast VT, and vulnerability testing permits assessment of defibrillation efficacy without inducing VF in most patients. This review reappraises ICD implant testing. At implant, defibrillation success is influenced by both predictable and unpredictable factors, including those related to the patient, ICD system, drugs, and complications. For left pectoral implants of high-output ICDs, the probability of passing a 10 J safety margin is approximately 95%, the probability that a maximum output shock will defibrillate is approximately 99%, and the incidence of system revision based on testing is < or = 5%. Bayes' Theorem predicts that implant testing identifies < or = 50% of patients at high risk for unsuccessful defibrillation. Most patients who fail implant criteria have false negative tests and may undergo unnecessary revision of their ICD systems. The first-shock success rate for spontaneous VT/VF ranges from 83% to 93%, lower than that for induced VF. Thus, shocks for spontaneous VT/VF fail for reasons that are not evaluated at implant. Whether system revision based on implant testing improves this success rate is unknown. The risks of implant testing include those related to VF and those related to shocks alone. The former may be due to circulatory arrest alone or the combination of circulatory arrest and shocks. Vulnerability testing reduces risks related to VF, but not those related to shocks. Mortality from implant testing probably is 0.1-0.2%. Overall, VF should be induced to assess sensing in approximately 5% of ICD recipients. Defibrillation or vulnerability testing is indicated in 20-40% of recipients who can be identified as having a higher-than-usual probability of an inadequate defibrillation safety margin based on patient-specific factors. However, implant testing is too risky in approximately 5% of recipients and may not be worth the risks in 10-30%. In 25-50% of ICD recipients, testing cannot be identified as either critical or contraindicated.

show abstract

“…Previous experimental studies provide conflicting evidence. Some show an increase in defibrillation threshold, [17][18][19] but others find no change 20,21 or even a decrease. 22 In an in vivo canine study, 20 acute regional ischemia did not elevate defibrillation energy requirement, whereas systemic hypoxia reduced the energy required to defibrillate.…”

Section: Dft 50 and Type B Defibrillation During Prolonged Global Iscmentioning

confidence: 99%

Early Recurrence of Ventricular Fibrillation After Successful Defibrillation During Prolonged Global Ischemia in Isolated Rabbit Hearts

Lin

Hsieh

et al. 2007

Cardiovasc electrophysiol

View full text Add to dashboard Cite

show abstract

Effects of Transient Myocardial Ischemia on the Ventricular Defibrillation Threshold

Abstract: This experimental study shows that transient myocardial ischemia markedly increases the DFT, suggesting that specific defibrillation algorithms should be designed for recipients of implantable defibrillators at risk of myocardial ischemia.

Cited by 19 publications

References 19 publications

Is all ventricular fibrillation the same? A comparison of ischemically induced with electrically induced ventricular fibrillation in a porcine cardiac arrest and resuscitation model*

Is all ventricular fibrillation the same? A comparison of ischemically induced with electrically induced ventricular fibrillation in a porcine cardiac arrest and resuscitation model*

The Dilemma of ICD Implant Testing

Early Recurrence of Ventricular Fibrillation After Successful Defibrillation During Prolonged Global Ischemia in Isolated Rabbit Hearts

Contact Info

Product

Resources

About