Dual chamber pacemaker evident. Ventricular lead has displaced tip lying near tip of atrial lead – c) Complete the following table identifying causes of pacemaker/defibrillator malfunction. Provide two examples/causes for each category (9 marks) Catergory of PPM Malfunction ECG Findings Example/Cause Failure to Sense Failure to Pace Oversensing Catergory of PPM Malfunction ECG Findings Failure to Sense Pacing (or at least pacing spike) Voltage of intrinsic cardiac activity occurring in middle of normal P too low to detect waves or QRS complexes Battery failure Mechanical problem with lead (fracture/displacement) Failure to Pace No pacing spikes for Mechanical problem with lead(s) atria/ventricles or both seen Battery failure Fibrosis at electrode/tissue interface Oversensing Oversensing Pacing spikes not appearing External electromagnetic field (inhibited) where they should occur interference abnormal pauses or appearing Detection of intrinsic electrical – – when they shouldn’t (inappropriate activity not assoc with atrial or triggering) ventricular contraction (e.g. muscle potentials, T wave) Inappropriate interaction between elements of pacing system Circular magnets can be used to alter the function of implanted devices. d) What is the usual effect of placing a magnet over a pacemaker? (1 mark) Initiates mode” effect can vary b/w devices but most commonly puts in asynchronous pacing mode “magnet – e) What is the usual effect of placing a magnet over a defib? (1 mark) defibrillator from firing Question 7 A 56 year old presents with a SOB and chest pain. He has recently been diagnosed with hypertension and started on perindopril and amlodipine. He presents to ED because he has measured a BP of 210/110 at home. He is convinced that he is going to have a stroke. You are concerned that he is having an aortic dissection. BP 230/120 P 130 Sats 99% RA RR 26
Dual chamber pacemaker evident. Ventricular lead has displaced – tip lying near tip of atrial lead c) Complete the following table identifying causes of pacemaker/defibrillator malfunction. Provide two examples/causes for each category (9 marks) Catergory of PPM Malfunction ECG Findings Example/Cause Failure to Sense Failure to Pace Oversensing Catergory of PPM Malfunction ECG Findings Failure to Sense Pacing (or at least pacing spike) occurring in middle of normal P waves or QRS complexes Voltage of intrinsic cardiac activity too low to detect Battery failure Mechanical problem with lead (fracture/displacement) Failure to Pace No pacing spikes for atria/ventricles or both seen Mechanical problem with lead(s) Battery failure Fibrosis at electrode/tissue interface Oversensing Oversensing Pacing spikes not appearing (inhibited) where they should occur – abnormal pauses – or appearing when they shouldn’t (inappropriate triggering) External electromagnetic field interference Detection of intrinsic electrical activity not assoc with atrial or ventricular contraction (e.g. muscle potentials, T wave) Inappropriate interaction between elements of pacing system Circular magnets can be used to alter the function of implanted devices. d) What is the usual effect of placing a magnet over a pacemaker? (1 mark) Initiates “magnet mode” – effect can vary b/w devices but most commonly puts in asynchronous pacing mode e) What is the usual effect of placing a magnet over a defib? (1 mark) defibrillator from firing Question 7 A 56 year old presents with a SOB and chest pain. He has recently been diagnosed with hypertension and started on perindopril and amlodipine. He presents to ED because he has measured a BP of 210/110 at home. He is convinced that he is going to have a stroke. You are concerned that he is having an aortic dissection. BP 230/120 P 130 Sats 99% RA RR 26
CARDIO-Q.docx