ECG in Pacemaker Malfunction Sriram Rajagopal, Southern Railway Hospital, Perambur,Chennai

ECG in “Pacemaker Malfunction” (ECGs in Pacemaker Function Assessment) Sriram Rajagopal, Southern Railway Hospital, Perambur,Chennai

Implantable Pacemaker Systems Contain the Following Components: Lead wire(s) Implantable pulse generator (IPG) A basic pacing system is made up of: Implantable pulse generator that contains: A power source—the battery within the pulse generator that generates the impulse Circuitry—controls pacemaker operations Leads—Insulated wires that deliver electrical impulses from the pulse generator to the heart. Leads also transmit electrical signals from the heart to the pulse generator. Electrode—a conductor located at the end of the lead; delivers the impulse to the heart.

Pseudomalfunctions Pseudomalfunctions are defined as: CorePace Module 4: Troubleshooting Pseudomalfunctions Pseudomalfunctions are defined as: Unusual Unexpected Eccentric ECG findings that appear to result from pacemaker malfunction but that represent normal pacemaker function Pseudomalfunctions should be ruled out as the cause(s) of an anomalous ECG strip before corrective measures are taken.

ECGs in Patients with Pacemakers Overview : Basic principles of pacing Background information required Systematic approach Examples with single chamber pacing Examples with dual chamber pacing

ECGs in Patients with Pacemakers Overview : Basic principles of pacing Background information required Systematic approach Examples with single chamber pacing Examples with dual chamber pacing

ECGs in Patients with Pacemakers What do pacemakers do ? Pace Sense – ( what ? ) Respond – Inhibit , Trigger or Dual Respond to increased metabolic demand by providing rate responsive pacing Provide diagnostic information stored by the pacemaker

Timing Intervals Are Expressed in Milliseconds One millisecond = 1 / 1,000 of a second Part of understanding timing intervals requires an acquaintance with milliseconds. Many Healthcare professionals are accustomed to measuring intervals in seconds. Timing intervals in pacing, however, are always measured in milliseconds. The exception to this is lower and upper rates, which are usually expressed in beats per minute/bpm. The graphic above shows intervals in milliseconds of a normal sinus beat. The entire graph represents 1000 milliseconds or one second of time. The smallest box on the ECG represents 40 milliseconds or .04 seconds. The medium box represents 200 milliseconds or .2 seconds.

Rate Conversion Conversion Pacing rate in PPM divided by 60,000 = ms 60,000 / 60 PPM = 1000 ms Interval in ms divided by 60,000 = PPM 60,000 / 1000 ms = 60 PPM 60,000 ms BPM

Paced Rhythm Recognition VVI / 60

Paced Rhythm Recognition VVI / 60

Paced Rhythm Recognition AAI / 60

Noncapture is Exhibited By: CorePace Module 4: Troubleshooting Noncapture is Exhibited By: No evidence of depolarization after pacing artifact This ECG strip shows loss of atrial capture, followed by a scheduled ventricular pace. Following the ventricular pulse, the marker channel recorded an intrinsic P-wave. Loss of capture

CorePace Module 4: Troubleshooting No Output Pacemaker artifacts do not appear on the ECG; rate is less than the lower rate When the pacemaker problem is no output, the marker channel shows pacing markers—AP or VP—although no artifact appears on the ECG. No output is defined as the failure to pace. Impulses are generated from the IPG, but is not transferred to the lead. Pacing output delivered; no evidence of pacing spike is seen

Fusion Beat Definition: The combination of an intrinsic beat and a paced beat. The morphology varies; in other words, a fusion beat doesn’t really look like a paced beat or an intrinsic beat. The pacemaker and the patient contribute to depolarization in Fusion beats.

Fusion Ventricular Fusion

Pseudofusion Beat Definition: A pacing pulse falls on an intrinsic beat. The pacing pulse is ineffective and the intrinsic complex is not altered. The pacemaker does NOT contribute to depolarization in Pseudofusion beats.

Pseudofusion Ventricular Pseudofusion

Dual-Chamber Systems Have Two Leads: One lead implanted in the atrium One lead implanted in the ventricle

Paced Rhythm Recognition The notation at the top refers to mode, lower rate, and upper rate parameters. This mode of operation can be described as atrial synchronous pacing or atrial tracking. DDD / 60 / 120

Paced Rhythm Recognition DDD / 60 / 120

Paced Rhythm Recognition Pacing in the atrium and ventricle is often described as AV sequential pacing. DDD / 60 / 120

Paced Rhythm Recognition DDD / 60 / 120

Sensing Sensing is the ability of the pacemaker to “see” when a natural (intrinsic) depolarization is occurring Pacemakers sense cardiac depolarization by measuring changes in electrical potential of myocardial cells between the anode and cathode

Sensitivity – The Greater the Number, the Less Sensitive the Device to Intracardiac Events Pacemakers have programmable sensitivity settings that can be thought of like a fence: with a lower fence more of the signal is seen; with a higher fence less of the signal is seen.

Sensitivity 5.0 Amplitude (mV) 2.5 1.25 Time If the system is sensing myopotentials, then raise the fence or increase the number of the sensitivity setting. The pacemaker will "see less" of the incoming signal. If the pacing system is not “seeing” intrinsic cardiac events, set the fence lower or decrease the number of the sensitivity setting. The pacemaker will then "see” more of the incoming signal. Time

Sensitivity 5.0 Amplitude (mV) 2.5 1.25 Time In this example, the sensitivity number is set higher than the signal. The pacemaker is unable to see any activity and undersensing will result. Time

Sensitivity 5.0 Amplitude (mV) 2.5 1.25 Time In this example, the sensitivity setting is set such that the pacemaker will likely sense the T wave. Oversensing will occur. Time

Scheduled pace delivered Intrinsic beat not sensed Undersensing . . . Pacemaker does not “see” the intrinsic beat, and therefore does not respond appropriately Scheduled pace delivered Intrinsic beat not sensed VVI / 60

Oversensing VVI / 60 ...though no activity is present Marker channel shows intrinsic activity... An electrical signal other than the intended P or R wave is detected Oversensing will exhibit pauses in single chamber systems. In dual chamber systems, atrial oversensing may cause fast ventricular pacing without P waves preceding the paced ventricular events.

ECGs in Patients with Pacemakers Overview : Basic principles of pacing Background information required Systematic approach Examples with single chamber pacing Examples with dual chamber pacing

ECGs in Patients with Pacemakers Basic Data : Clinical details – age , indication for pacing, time since implant etc Type of pacemaker Programmed parameters Magnet Behaviour Special features

CorePace Module 4: Troubleshooting Magnet Operation Magnet application causes asynchronous pacing at a designated “magnet” rate Magnet operation varies within different product lines and from manufacturer to manufacturer, but will usually involve a rate change when the magnet is applied. The Threshold Margin Test (TMT) is part magnet operation for most of Medtronic’s devices. The following operation describes magnet operation and TMT for most Medtronic devices: Three beats at 100 bpm, followed by a magnet rate of 85 The third beat has an automatic pulse width decrement of 25% (loss of capture would indicate that the stimulation safety margin is inadequate) Dual chamber devices will shorten the AV delay to 100 ms Elective replacement indicators will change the rate from 85 to 65 and the mode from dual to single chamber pacing It is important to remember that magnet modes vary from manufacturer to manufacturer, and from device to device. While recent Medtronic devices use the above rule of thumb, many older devices used the programmed lower rate as the magnet rate, or would decrease the rate by a certain percentage as a battery depletion indicator. Kappa devices have a feature called Extended TMT. Extended TMT is a programmable feature and will operate as follows: TMT is performed at 100 ppm with the pulse width reduced by 25% on the third pulse, 50% on the fifth pulse, and 75% on the seventh pulse. This type of operation is extremely useful in assessing adequate safety margins, by simply using a magnet.

Rate Responsive Pacing CorePace Module 4: Troubleshooting Rate Responsive Pacing An accelerating or decelerating rate may be perceived as anomalous pacemaker behavior If a patient is active it is easy to equate rate increases with rate responsive pacing. Some patients may experience “false positive” increases in rate from their sensors. In the case of a piezoelectric crystal, the pacemaker may begin pacing at a faster rate if, for example, the patient is either lying on the side that the pacemaker is implanted on or experiencing a bumpy car ride. Minute ventilation sensors measure the change in respiration rate and tidal volume. If a patient experiences rapid respiration resulting from a cause other than exercise (e.g., hyperventilation), the pacemaker may begin pacing at a faster rate. VVIR / 60 / 120

CorePace Module 4: Troubleshooting Hysteresis Allows a lower rate between sensed events to occur; paced rate is higher Hysteresis Rate 50 ppm Lower Rate 70 ppm Hysteresis provides the capability to maintain the patient’s intrinsic heart rhythm as long as possible, while providing back-up pacing if the intrinsic rhythm falls below the hysteresis rate. Because hysteresis exhibits longer intervals between sensed events, it may be perceived as oversensing.

ECGs in Patients with Pacemakers Overview : Basic principles of pacing Background information required Systematic approach Examples with single chamber pacing Examples with dual chamber pacing

ECGs in Patients with Pacemakers Single chamber pacing : Identify underlying intrinsic rhythm if any ( in each chamber) Verify appropriate sensing ( if possible ) Verify capture Measure base rate and check if appropriate Identify any variations in intervals and interpret Identify causes of inappropriate sensing or pacing

ECGs in Patients with Pacemakers Overview : Basic principles of pacing Background information required Systematic approach Examples with single chamber pacing Examples with dual chamber pacing

Single Chamber ECG Analysis Programmed Parameters Mode………………………………………….. VVI Base Rate……………………………………….. 70 ppm Magnet Response…………………….. Battery Test Hysteresis Rate………………………………… Off ppm T Temporary programmed value 1.0 Second 7 Mar 2000 23:20 1

ECG #1 VVI Normal Capture and Sensing 1

Single Chamber ECG Analysis Programmed Parameters Mode………………………………………….. VVI Base Rate……………………………………….. 70 ppm Magnet Response…………………….. Battery Test Hysteresis Rate………………………………… Off ppm T Temporary programmed value 1.0 Second Jun 14 1999 2:57 pm 2

ECG #2 VVI Normal Sensing Capture unknown 2

Single Chamber ECG Analysis 3

ECG #3 VVI Normal Capture and Sensing with initiation of Hysteresis 3

Single Chamber ECG Analysis 4

ECG #4 VVI Loss of Ventricular Sensing Ventricular Undersensing with Functional loss of capture on the second to last beat 4

Single Chamber ECG Analysis 5

ECG #5 VVI Loss of Ventricular capture with functional loss of sensing

Single Chamber ECG Analysis 6

ECG #6 VVI Normal Capture Ventricular Oversensing 6

Single Chamber ECG Analysis 10

Single Chamber ECG Analysis 10

ECG #10 VVI Capture Unknown Normal Sensing Normal initiation of Hysteresis 10

Single Chamber ECG Analysis 12

Single Chamber ECG Analysis 12

ECG #12 VVI Normal Capture Ventricular Undersensing 12

Single Chamber ECG Analysis 13

Single Chamber ECG Analysis 13

ECG #13 VVI Loss of Ventricular Capture Normal Sensing 13

Single Chamber ECG Analysis 15

ECG #15 VVIR Normal Capture and Sensing under Sensor drive 15

Crosstalk

ECGs in Patients with Pacemakers Overview : Basic principles of pacing Background information required Systematic approach Examples with single chamber pacing Examples with dual chamber pacing

A Systematic Approach Measure Base Rate Measure AV/PV (PAV/ SAV) Interval Verify Atrial capture Verify Atrial sensing Verify Ventricular capture Verify Ventricular sensing Verify Underlying rhythm Document

Dual Chamber ECG Analysis Base Rate 60 ppm MTR 120 ppm AVD 200 ms PVARP 250 ms ECG # 3

Answer ECG #3 Loss of Atrial Capture Normal Atrial Sensing Base Rate 60 ppm MTR 120 ppm AVD 200 ms PVARP 250 ms Loss of Atrial Capture Normal Atrial Sensing Normal Ventricular Capture Ventricular Sensing Unknown

Dual Chamber ECG Analysis Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 150 ms PVARP 250 ms ECG # 5

Answer ECG #5 Normal Atrial Capture Atrial Sensing Unknown Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 150 ms PVARP 250 ms Normal Atrial Capture Possible Psuedofusion on 4th atrial output Atrial Sensing Unknown Loss of Ventricular Capture Normal Ventricular Sensing Functional Loss of Ventricular Sensing

Dual Chamber ECG Analysis Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 200 ms PVARP 250 ms ECG # 10

Answer ECG #10 Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 200 ms PVARP 250 ms Normal Atrial Capture with one beat showing functional loss of atrial capture Atrial Undersensing Normal Ventricular Capture Ventricular Sensing Unknown

Dual Chamber ECG Analysis Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 200 ms PVARP 250 ms ECG # 12

Answer ECG #12 Normal Atrial Capture Normal Atrial Sensing Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 200 ms PVARP 250 ms Normal Atrial Capture Normal Atrial Sensing Normal Ventricular Capture with two beats of functional loss of capture Ventricular Undersensing

Dual Chamber ECG Analysis Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 200 ms PVARP 250 ms ECG # 20

Answer ECG #20 Initiation of 2:1 block upper rate response Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 200 ms PVARP 250 ms Initiation of 2:1 block upper rate response Normal Upper Rate Behavior Operation

Dual Chamber ECG Analysis Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 150 ms Min. PV 88 ms PVARP 250 ms ECG # 24

Answer ECG #24 Normal Atrial Capture Normal Atrial Sensing Base Rate 60 ppm MTR 120 ppm AV 200 ms PV 150 ms Min. PV 88 ms PVARP 250 ms Normal Atrial Capture Normal Atrial Sensing Normal Ventricular Capture Ventricular Sensing Unknown Initiation of a Pacemaker Mediated Tachycardia (PMT) with following a PVC

ECGs in Patients with Pacemakers Conclusions : Familiarity with basics of pacemaker function Knowledge of clinical background and details of pacing system Programmed parameters – essential Familiarity with special features Systematic approach

Thank you for your kind attention !

ECGs in Patients with Pacemakers

ECGs in Patients with Pacemakers

ECGs in Patients with Pacemakers

ECGs in Patients with Pacemakers

ECGs in Patients with Pacemakers

ECGs in Patients with Pacemakers

ECGs in Patients with Pacemakers

ECGs in Patients with Pacemakers

ECGs in Patients with Pacemakers