By Sam Annor (EE5811-Biomedical Instrumentation-Fall 2007).

Background Defibrillation process Defibrillator types AED usage-pictorial AED usage-video Algorithm- how VF is detected What does it mean algorithm mean? Results and analysis -failure ICD usage ICD failure analysis Safety/risk analysis Conclusion Acknowledgement to Collaborators References

It is estimated that Cardiovascular diseases account for the majority of death in the US with a total toll of about 1 1 million people per annum 1 Estes III, Mark. “Automatic External Defibrillators in the Public Domain – Am I Ready to Use One?” Circulation 112 (2005): e349–e351.

Ventricular Fibrillation(VF) When a ventricular arrhythmia (irregular heartbeat) becomes very fast and irregular, it's called ventricular fibrillation Ventricular Tachycardia(VT) is a tachycardia, or fast heart rhythm that originates in one of the ventricles of the heart.

The process used to curtail Ventricular Fibrillation(VF) and Ventricular Tachycardia(VT) Unless treatment is given in 5 to 10 minutes, ventricular fibrillation causes death. Devices Used in the process- Defibrillators Two Types- Automatic External Defibrillators(AEDs) -in vitro Implantable Cardioverter-Defibrillators(ICDs) – in vivo

have electronic analyzer circuitry that monitors the cardiac rhythm and alerts when a defibrillation shock is needed.

AED in use

Video of AED use

The algorithm for recognizing VF and committing to shock delivery is as follows: (1) The AED will begin to charge if it detects at least two "positive intervals" within a 9.6 sec period. A positive interval is defined as six or more deflections that are at least mV (1.5 mm trough-to- peak) in amplitude with a maximum slope of 3.2 mV/sec (termed VF counts) occurring in a 2.4 sec period (rate at least 150/min). (2) The AED will discharge if it detects a third positive interval within 7.2 sec of the start of capacitor charging. Thus it takes a minimum of 4.8sec (2 x 2.4) to begin charging; it requires a minimum of 7.2 sec (3 x 2.4) to commit to a shock after being presented with VF.

Algorithm-recognition patterns

 Smaller cardiac mass in Children will cause their VF to differ from Adult.  Children have faster supra VT than adult

Results

AED failed to properly diagnose VT hence with an average sensitivity of 56% However for VF the sensitivity was 96% on the average

Used when ventricular fibrillation and tachycardia are frequent and continuous defibrillation are needed.

A 36-year-old man with an ATLAS+ DR V- 243 (St. Jude Medical, Inc., St. Paul, MN, USA) dual chamber implantable cardioverter defibrillator (ICD) received a shock while cycling, but was otherwise asymptomatic Medtronic leads are designed for use with an ICD as part of a cardiac system. Leads are intended for delivering therapies and/or sensing in the atrium and/or ventricle of the heart

Doesn’t everyone know how to be safe? Several attempts are done to ensure safety like FDA regulation, various compliance- annual trainings, increased litigation, etc. The fact remains safety education is hard to sell, hard to pay attention to and hard to remember. Why? -reluctance to learn -resistance to change

Federally, FDA is charge with the mandate of ensuring the medical devices are SAFE. However the FDA relies on the manufacturers to provide with data on malfunction of the device. If your are the manufacturer- Will you always report the needed data?

Tom O’Dea Ph. D., P. E. C.C.E –Healthcare Engineering Prof. Jim Holte

1. Estes III, Mark. “Automatic External Defibrillators in the Public Domain – Am I Ready to Use One?” Circulation 112 (2005): e349–e “Defibrillation.” Wikipedia. 1 Dec KR Stults, DD Brown and RE Kerber. “Efficacy of an automated external defibrillator in the management of out-of- hospital cardiac arrest: validation of the diagnostic algorithm and initial clinical experience in a rural environment” Circulation 73 (1986): Frank Cecchin, Dawn B. Jorgenson, Charles I. Berul, James C. Perry, A. Andrew Zimmerman, Brian W. Duncan, Flavian M. Lupinetti, David Snyder, Thomas D. Lyster, Geoffrey L. Rosenthal, Brett Cross and Dianne L. Atkins “Is Arrhythmia Detection by Automatic External Defibrillator Accurate for Children? : Sensitivity and Specificity of an Automatic External Defibrillator Algorithm in 696 Pediatric Arrhythmias” Circulation 103 (2001):

Based on my presentation why was VT showing lower Sensitivity readings compared to VF in children under 13 years old?