1 Overview  Problem Review  Solutions Review  Results  Assessment and Feedback  Ethics: “Moral Blindness and the Guidant Recall”  Closure Writing Pairs

2 Problem Review  The heart can suffer from arrhythmias that disrupt its normal function.  Ventricular Tachycardia (VT) – heart beats too fast with no defined rhythm, does not pump enough blood to the body. Without treatment almost always fatal.  Superventricular Tachycardia (SVT) – heart beats too fast but with defined rhythm. Unpleasant but rarely fatal.

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4 Implantable Cardioverter Defibrillator  ICDs are implanted in high-risk patients  Uses an algorithm to detect VT and SVT  When a VT is detected, the ICD delivers a life-saving shock to the heart

5 Solution Methods  Two ICD algorithms to classify VT and SVT ECG signals.  Create a Matlab program, main file and functions, that will implement the Derivative Method (DM)  Use the EFF Calculator function to distinguish between VT and SVT

6 Overview of the Derivative Method  Detect three R-peaks from an ECG test signal  Extract the 80ms interval before each peak  Calculate the first derivative of each of the three 80ms intervals  Compute the average of the three derivatives  Rectify the average derivative signal  Normalize the signal to the maximum SR value  Plot these DM results for the ECG test signal against the DM results for the SR signal Note the onset time for the ECG test signal by visual inspection (i.e. looking at it)!

7 Derivative Method – continued  A threshold value is calculated from the analysis of the known ECG signals.  The DM algorithm is used to analyze each unknown ECG signal; the threshold is applied to the resulting onset time and the ECG is classified as VT or SVT.

8 Working in the frequency domain the EFF algorithm can classify VT and SVT signals.  First, the EFF algorithm is used to analyze known ECG signals; one plot provides a quick visual comparison of EFF values for VT and SVT.  Next, a threshold value is calculated from the analysis of the known signals.  Finally, the EFF algorithm is used to analyze each unknown ECG signal; the threshold is applied to the EFF value and classifies the ECG as VT or SVT.

9 Results: Some Hints  A correct implementation of the Derivative Method will misclassify two unknown signals.  A correct use of the EFF Calculator will correct one of these misclassifications.

10 Trade Offs  Speed and Accuracy  Recall our hypothesis from the Introductory Lecture  Speed is determined by how long it takes to calculate a solution  Hint: cputime command in Matlab

11 Accuracy  Accuracy is determined based on misclassification and the cost function.  Misclassifying an SVT as a VT will give the patient an unnecessary shock: unpleasant but not life threatening.  However, misclassifying a VT as an SVT and not giving a shock: likely death of the patient.

12 Accuracy Considerations  Example: An ICD that misclassifies only 1:100 signals may be considered less accurate than one that misclassifies 2:100 signals.  This is true if the 1:100 misclassifies a VT as an SVT while the 2:100 misclassifies SVTs as VT.  Because the consequence of misclassification of a VT is severe, the 1:100 is considered less accurate.

13 Report Considerations  What kind of signal is corrected from the DM to the EFF method?  Is the DM or EFF method more accurate?  Under what conditions?

14 Assessment and Feedback You must demonstrate your team’s project results to your lab instructor or TA in lab this week  It is your team’s responsibility to initiate this demonstration  All team members must be present  All team members must participate in the demonstration  All team members must be prepared to answer questions  Your team’s demonstration should take about 10 minutes

15 The accuracy of your team’s results is worth 20% of your project score. Your team will receive a copy of the scoring table for your results assessment

16 Characteristics of Effective Teams  Frequent, honest communication  Divide-and-conquer with expert follow-up  Balance and exploit strengths of individuals AND teams  Weekly meetings outside of lab  EVERY team member present and prepared for meetings and labs  Use team roles to make expectations and obligations clear to everyone  Facilitator: it is your job to make sure all team members are up to speed Remember the extra credit on the exams—extra 5% if ALL team members score ≥ 80%!

17 Ethics: when dealing with the heart mistakes cost lives—Guidant ICD recall.  In 2002 Guidant discovered and fixed a flaw in its ICD devices. The flaw was a short circuit that drained the battery and prevented the life saving shock from being administered.  There were 20,600 patients implanted with flawed devices, but Guidant did not expose the flaw until 2005 when it was shamed into issuing an advisory telling patients not to have the devices replaced.

18 Ethics – continued  Guidant claimed that the probability of the ICD failing was so low that the surgery to replace the old device with a new one was more dangerous than the flawed device.  However,  Risk = (Probability of harm) x (Severity of harm)  Death is an extremely high severity of harm  Different people have different “utility functions”  Guidant did not warn patients and doctors—so patients did not get a chance to exercise their utility functions

19 Ethics – continued  Ultimately the FDA recalled Guidant’s flawed ICDs. “there is a reasonable probability that if a particular device is malfunctioning, the malfunctioning device will cause serious adverse health consequences or death.”

20 Ethical and Legal Issues  Understand the brief review of ethical theory  Review the IEEE Code of Ethics  Intellectual property: what it is and some examples  How to think about and manage an ethical dilemma

21 Closure Writing Pairs  Team up with one of your neighbors  Write 2-3 sentences describing the major point you learned in the project and the main unanswered question you still have  Write your paragraph in the online system  Sign your names and submit