Final Flashcards
What is NASPE
North American Society of Pacing and Electrophysiology
What is NASPE (North American Society of Pacing and Electrophysiology) now called?
HRS (Heart Rhythm Society)
What is HRS
Heart Rhythm Society
What system does the ACC and HRS use to classify their guidelines?
A ‘Class System,’ or “Classes”
Define Class I
Conditions for which there is evidence and/or general agreement that a given procedure or treatment is beneficial, useful, and effective.
Define Class II
Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment
Define Class IIa
Weight of evidence/opinion is in favor of usefulness/efficacy
Define Class III
Condition for which there is evidence and/or general agreement that a procedure/treatment is not useful/effective and in some cases may be harmful.
Is a slow heart rate (bradycardia) without symptoms enough to indicate pacemaker therapy?
No. Low heart rates can be physiological, as in the case of athletes in peak condition or age related, as in young adults. Symptoms alone (without a low heart rate) can be caused by a variety of other conditions, probably unrelated to the heart. Class I indication for pacemaker therapy for Bradycardia includes that the patient is symptomatic.
What is one of the main indications for permanent pacemaker ?
AV Block is the main indication
For Type I second degree AV block (Wenkebach), why does the P wave eventually not conduct to the ventricle?
The RP will eventually shorten to the point that a P wave falls into the refractory period and is blocked, not allow for the P wave to conduct to the ventricle.
What is the only rhythm disturbance that does not require symptoms for indication of a permanent pacemaker?
Third degree AV block (absence of AV conduction)
True/False - Any type of sinus node dysfunction with associated, documented symptoms is a Class I pacing indictation
True
What can a hypersensitive carotid sinus syndrome cause?
Syncope
What is ‘vasovagal syncope’ and what causes it?
- Symptoms of nausea and light sensitivity.
- Vasovagal syncope can be triggered by pain, stress, anxiety, or crowded conditions and there is evidence to suggest that it may be hereditary.
True/False - The key element in a pacing indication is a documented and symptomatic episode
True
True/False - Syncope is, in and of itself, not necessarily an indication for pacing, although it may be caused by any number of conditions that can be treated by a pacemaker.
True
What are the four parts of a pacemaker system?
1) Pulse generator
2) lead(s)
3) programmer
4) the patient
Define ‘sensing’ of a pacemaker
Pacemakers receive input from the heart through the pacing lead electrodes in a function known as ‘sensing’
What is the purpose of sensing?
To allow the pacemaker to assess what the heart is doing and to pace in response to the patient’s intrinsic rhythms (or lack thereof). The input the pacemaker receives comes in the form of electrical energy detected by the lead’s electrodes and transferred to the device.
What is the starting voltage and resistance of a new lithium-iodine battery pacemaker?
Classified as having 2.8 V and about 10,000 ohm resistance
What are values in voltage and resistance is considered depleted in a lithium-iodine pacemaker?
1.8 V and 40,000 ohms.
Which type of lead uses less energy from the generator, a high-impedance lead or a low-impedance lead?
high-impedance lead
True/False - Leads with a lower impedance value save battery energy, while leads with a higher impedance value use more battery energy
False - Leads with higher impedance values probably save battery energy, while leads with lower impedance values likely use more battery energy.
True/False - The duration of the output pulse is the biggest controllable factor in device longevity
False - The size of the output pulse is the biggest controllable factor in device longevity.
Define ‘output pulse’
An output pulse is defined by its pulse amplitude or height (measured in V) and its pulse duration or width (measured in msec).
Regarding output pulse, what is the value of measure for the pulse amplitude?
Volts
Regarding output pulse, what is the value of measure for the pulse width or pulse duration
milliseconds
What factors affect the pacing threshold on any given patient?
Many factors can affect the pacing threshold, and the biggest influences - drugs and disease progression - are more common in the pacemaker set than the general population. As a result, just because a clinician can determine a value for the pacing threshold of an individual today does not mean that the pacemaker should be set at that value. If that particular pacing threshold was taken at the “low point” of the day, it may not work well when the person experiences natural circadian changes in his pacing threshold.
What is a ‘strength-duration curve’
The visual depiction of pacing threshold energy output in volts and milliseconds, for the purposes of determining pacing thresholds (Rheobase and chronaxie)
What is ‘Rheobase’
Rheobase is the point at which the plateau begins and roughly establishes the minimum voltage requirements to capture the heart.
What is ‘Chronxie’
The point at which twice the Rheobase voltage value meets the curve is defined as chronaxie. Setting a pacemaker to the chronaxie value provides a safety margin for capture.
Asynchronous pacing means that the device paces but no longer____________
Senses
True/False - Most physicians establish the pacing threshold and then double it as the ‘safety margin’ to make sure the output pulse is always sufficiently large to capture the heart.
True
What are the two functions of a pacemaker lead?
1) it delivers signals (output pulses) from the implanted device to the heart
2) it transmits signals (electrical activity) from the heart back to the implanted device.
What is a passive fixation lead?
Passive-fixation leads rely on some sort of extension at the distal end that gets lodged in the trabeculae of the heart. These extensions vary in size, shape, and structure and may be called tines, fins, helices, or stabilizers. The most common passive-fixation lead used today is the tines lead. Typically used in the right ventricle, the tines of the lead catch in the dense trabeculae of the endocardium and give the lead some stability.
What is an active lead
An active-fixation lead has a screw, hook, or helix that must penetrate the endocardial tissue to secure the lead. The most popular active-fixation lead used today is the extendable-retractable helix. With this lead, the corkscrew-shaped helix remains safely within the distal tip of the lead during implantation and venous passage. Once the implanting physician has determined the proper lead location, the proximal end of the lead can be manipulated to extend the helix out of its protective sheath. The extendable0retractable design was created in part to allow active-fixation leads to pass through the tricuspid valve without “catching”.
Inflammation of the lead insertion point causes rises in _________
pacing thresholds
An active lead has
helix that screws
A passive lead has
tines
What is the theoretical mechanism of action to the cardiac tissue of a steroid eluting lead
The drugs in a steroid-eluting lead minimize the inflammation and almost eliminate the initial threshold rise characteristic of non-steroid-eluting leads. Patients who receive steroid-eluting leads experience less dramatic threshold changes as the system shifts from acute to chronic. The slow release of the steroid helps manage the long-term threshold.
Ohms law
I = V/R or also V = IR
A low or high impedance pacemaker is an efficient pacemaker
Low impedance is efficient for the pacemaker. A low impedance value means the device is able to deliver more current or electricity.
True/False - While relatively low impedance is a good thing for the pacemaker, the electrode itself benefits from a high impedance value, since high impedance reduces the amount of current flowing through it, and thus saves energy.
True
When it comes to impedance, it is good for a pacemaker to have a ____ impedance and it is good for a lead (or electrode) to have ____ impedance.
low (pacemaker)
high (lead)
Any significant change (200 ohm or more) in a lead impedance value over time can be indicative of a _______.
failure.
What is ‘Far-field’ R wave sensing
Far-field R wave sensing occurs when the atrial lead picks up signals that actually come from the ventricle, but inappropriately attributes them to the atrium.
True/False - In terms of function, there is no difference between an atrial and ventricular lead. Some implanters prefer to use a J-shaped lead in the atrium, but shape is the only difference in that lead.
True
Can bipolar leads be programmed as unipolar?
Yes
True/false - Bipolar leads are more common in pacing systems older than 15 years.
False. Unipolar systems are older and more common in pacing systems older than 15 years.
What are the measured values of a typical lead impedance?
500 - 1200 ohms
What does a low lead impedance indicate?
Insulation defect
What does a high lead impedance indicate?
Lead fracture
Regarding pacing thresholds, how is a 100% safety margin assured?
Double the output pacing voltage of the lowest threshold capture.
_______ Is the energy efficient point on the strength duration curve.
Chronaxie
What typically happens to pacing threshold over the next month following implant?
Threshold increases, but eventually will decrease back towards the implant value by three months.
In the pacing code known as NBG codes, what does the 1st, 2nd, 3rd, and 4th letter of the code describe?
1st-pacing site
2nd-sensing site
3rd-sensing modality
4th-rate responsiveness.
What causes a pneumothorax in device implant
A subclavian stick
What are the four (4) major complications associated with device implant?
1) pneumothorax
2) pacemaker pocket hematoma
3) myocardial perforation (cardiac tamponade)
4) infection
What does ICD stand for
Implantable cardioverter-defibrillator
What is an ICD used to treat?
Ventricular tachycardia
What are the typical indication for an ICD
VT or VF not in a setting of an MI; Syncope w/ LV dysfunction, EF of 35% with at least a NYHA class I, EF of 30% post 40 days MI, non-sustained VT post MI with <40% EF.
What is ATP?
Anti-tachycardia pacing. Pacing that is faster than the tachycardia, a therapy to tachycardia.
What does NIPS stand for regarding ICD testing?
Non-invasive programmed stimulation
How is NIPS performed?
Performed by inducting VT and/or VF. Tachycardia is induced by the implanted device delivering a 1 joule shock on the T wave after a burst/PES drive train. Once VT/VF is induced, then the implanted device will analyze and attempt to shock the patient out of the rhythm. NIPS is performed to determine successful DFT and safety margins.
What is ‘DFT’ and what does it stand for?
DFT is Defibrillation Threshold, which VT/VF is induced by shock on T to determine the minimum threshold at which a patient is successfully cardioverted by the implanted ICD (how many joules was required to shock the patient out of VT/VF).
How many joules is necessary for an adequate defibrillation ‘safety margin’ and why is it necessary?
10 joules from the maximum output of the ICD is the safety margin. Necessary as a safety net to assure successful termination of tachycardia.
Define the term ‘De Novo’
Means ‘from new,’ a new device or procedure that had not been experienced. In this context, de novo means an implant device is new to the patient.
True/False - A patient with a QRS of 135 ms, EF of 30% and CHF of class III has indications for a Bi-V ICD
True
What does the acronym CRT stand for ?
Cardiac Resynchronization Therapy
Is CRT synonymous with Bi-V
Yes
What population of patients is CRT shown to be beneficial for?
The population of patients that medical therapy has reached its limits in regards to CHF
What percentage of patients with CHF have bundle branch blocks?
15-30%
In these patients with BBB, how does the asynchrony affect them?
The BBBs greatly reduce the efficiency of the ventricle in patients with heart failure by reducing systolic function and increasing systolic volume.
How does resynchronization therapy improve patient conditions?
Resynchronization therapy re-coordinates the beating of the two ventricles concurrently, whereas a typical pacemaker only the right ventricle.
True/False - The benefits of long term CRT decreases the risk of death and complications related to heart failure in patients with AV conduction delays
True
What are the overall benefits of CRT
Reduced degree of ventricular dyssynchrony, increase in LV EF, and decrease in the left ventricular end-diastolic dimension, and magnitude of mitral valve. Additionally, CRT improves quality of life, increased exercise capacity, and decreased mortality.
True/False - Phrenic nerve stimulation is preferred in CRT implantation
No. If phrenic nerve stimulation is encountered, implanter may need to reposition the lead.
True/False - Two thirds of patients can expect a NYHA class improvement and 6% point increase in EF (with BiV)
True
What are the two reasons that a lead extraction may need to be performed?
1) remove infected hardware
2) make room for a newer lead
Is a back up surgical team necessary during a lead extraction and why or why not?
Yes, surgical back up is necessary because the lead extraction procedure is not a benign procedure. The procedure has significant complication associated with it that require immediate surgery to address.
What are the complication to a lead extraction?
1) vascular/cardiac perforation
2) fragmented or dislodged foreign body
3) immediate cardiac surgery
If a device gets infected and the patient remains septic despite antibiotics, how much of the implanted hardware must be removed?
All hardware must be removed
Describe the technical aspects of the laser used in lead extractions
Ultra violet Excimer laser light, 308 nanometer wavelength, penetrates only 50 microns ahead of sheath tip, cool laser at 50 degrees Celsius.
How many degrees does the laser deliver?
50 degrees Celsius
How many microns does the laser penetrate into?
50 microns
How does the laser interact with tissue?
The laser breaks down scar tissue holding the leads in place, thereby permitting removal.
Which technique is more effective at lead extraction, laser or manual mechanical?
Laser is more effective and time efficient.
True/False - patients should be well hydrated, with food withheld for about 8 hours before the operation
True
In pocket preparation, where is the incision made for a typical pacemaker implant?
After the patient is properly anesthetized, a small incision deep enough to reach the pectoralis fascia is made approximately an inch below and parallel to the clavicle.
What are the common sites of venous entry for a device implant
Subclavian and cephalic veins
What is a Seldinger technique
Vessel access technique in which an 18-gauge needle attached to a 10-ml syringe is introduced through the pocket incision. The needle should be inserted with the bevel side down and then advanced slowly along the tissue between the medial and middle thirds of the clavicle and headed toward a point just above the notch in the sternum. On reaching the clavicle, the needle’s angle of entry is increased until the tip slides under the bone.
True/False - Accidental arterial puncture is determined by the immediate presence of pulsing, bright red blood
True
True/false - repeated unsuccessful attempts to find the subclavian vein with the Seldinger technique suggests that the vessel is occluded or in an abnormal position.
True
What is the landmark for venipuncture with using the Seldinger technique?
Between the first rib and the clavicle at the lateral edge of the sternum, described in a 40 degree arc.
How is successful puncture confirmed in the subclavian vein using in the Seldinger technique
Confirmed by aspirating blood into the syringe
How do you confirm wire position once the syringe is removed and the introducer wire is advanced through the needle into the right side of the heart
Confirmed and advanced with fluoroscopy
What French sizes are introducers generally available in?
8 - 14 French
What lumen size is larger, a smaller French number or a large French number
Large French size = larger lumen size
Describe the cephalic vein approach?
Although considered more of a “surgical approach” than the Seldinger subclavian stick, the actual surgical skills required are not extreme and the location of the cephalic vein is usually not problematic. Once the vein is identified, it should be exposed and a small incision made. The guide wire is passed into the cephalic vein and gently maneuvered into the right side of the heart under fluoroscopic observation. The introducer is then placed over the guide wire, just as was done in the subclavian approach. In the cephalic approach, however, the guide wire is left in place as the lead (with stylet inside) is gently maneuvered into the right side of the heart.
True/False - Most right ventricular leads are placed in the apex
True
True/False - One technique to get the lead to ‘fall’ into place is to have the patient take deep breaths
True
True/False - after the ventricular lead is placed, the atrial lead is inserted before checking the ventricular electrical values
False. Electrical values of the ventricular lead are usually checked before inserting an atrial lead.
True/False - Atrial lead placement tends to be easier than ventricular lead placement because the atrium has thicker tissue
False - atrial lead placement tends to be more difficult than ventricular lead placement because the atrium is smaller, has thinner walls with less trabeculae.
True/False - The most common atrial pacing site is the right atrial appendage
True
True/False - In order to confirm satisfactory lead placement, electrical measurements must be taken before the leads are plugged into the pacemaker
True
What is the ideal sensing threshold in the atrium
2 -3 mv in the atrium
What is the ideal sensing threshold in the ventricle
4 - 10 mv in the ventricle
What is the NBG code and where is its name derived from?
Clinicians needed a generic, shorthand way of describing pacemakers in terms of functionality. Today, the “official” code for pacemakers and ICDs is known as the NBG code (NBG is a blend of NASPE and BPG). Those code letters for the first position are A for atrium, V for ventricle, D for dual meaning both atrium and ventricle, and O if no pacing occurs at all. Thus, any pacemaker code that starts with D (DDI, DDDR, DOO) means that the pacemaker paces in both atrium and ventricle.
What is the first letter in the NBG code represent?
The “first position” describes the chamber(s) that are paced
What does the second letter in the NBG code represent?
The chamber(s) in which the device senses signals.
What does the third letter in the NBG code represent?
It describes how the pacemaker responds to a sensed event. If the pacemaker is inhibited (if it withholds a pacing output pulse in response to a sensed event) then it has an I in the third position. Ex: VVI device: paces in the ventricle, senses in the ventricle, and when it senses an event in the ventricle, it inhibits or withholds a pacing output.
What does the fourth letter in the NGB code represent?
The 4th position adds an R for rate modulation or rate response. This varies its rate based on the perceived activity levels of the patient. Thus, an AAIR device paces in the atrium, senses in the atrium, inhibits or withholds a pacing output when it senses atrial activity, and its rate modulated so that the pacing rate increases with activity. Non-rate modulated devices may use an O (no rate modulation) or just omit a letter.
In the NBG codes, what does “O” stand for?
O may be used to describe a device with no sensing capabilities.
In the NBG codes, what does “D” stand for?
D for “dual” meaning both atrium and ventricle.
In the NBG codes, what does “I” stand for?
If the pacemaker is inhibited (if it withholds pacing output pulse in response to a sensed event) then it has an I in the third position. Most single chamber devices in use are inhibited devices.
In the NBG codes, what does “S” stand for?
S is commonly used and understood, but is not part of the official NBG code. When a physician implants an SSI device into a patient with a lead in the ventricle, the device is more accurately called a VVI pacemaker. Manufacturers can use S for “single chamber” and it is understood that this device will only be an A or V device after the physician has chosen the chamber for its application.
In the NBG codes, what does “R” stand for?
R designator in the 4th position applies to any sort of rate modulation; piezoelectric sensor, accelerometer, minute ventilation, and even temperature sensing pacemakers. Thus, R does not tell you what type of rate modulation is in effect, only that the system modulates the rate based on anticipated patient needs using some method.
True/False - As a rule of thumb, the code used to describe a device is the highest or most sophisticated level of programmability in that device.
True
True/False - A device labeled DDDR is capable of rate modulation, whether or not the physician decides to turn it on.
True
True/False - Mode codes are used in product labeling (to show the LOWEST attainable mode the device can achieve) or as a clinical abbreviation for how the device is programmed or is functioning.
False. Mode codes are used in product labeling (to show the HIGHEST attainable mode the device can achieve) or as a clinical abbreviation for how the device is programmed or is functioning.
Single-chamber pacing is based on the two fundamentals of permanent pacing:
1) pacing (capturing the heart)
2) sensing (seeing the hearts own intrinsic signal)
The depolarization in response to electrical energy from the pulse generator is called _______
Capture
Pacemaker output pulse appears on the surface ECG as a small vertical line called a _____ or sometimes called a _______.
spike; pacing artifact
What does a pacing artifact before the P wave mean regarding pacemaker output?
Capture a pacing artifact right before a P wave means a pacemaker output was delivered right before an atrial depolarization
Describe the QRS morphology in stimulated and captured right ventricular apex?
When the ventricles are stimulated by the electric impulse, t he resulting QRS is wide and looks unusual. Therefore, ventricular capture is largely seen when the pacing spike is immediately followed by a wide (left bundle branch type) QRS. This changed QRS morphology occurs because the pacing lead stimulated the right ventricle first and then the impulse spreads through the septum to activate the left ventricle.
see images for image questions
see images
What are two (2) causes for ‘functional non-capture’?
1) when the pacemaker spike falls into the hearts intrinsic refractory period. During this period the heart is electrically incapable of responding to the pacemaker output.
2) another cause of non-capture can be an output pulse that does not have enough energy to depolarize the heart.
True/False - The pacing threshold is constant over the course of the day, despite disease progression, drugs, and even posture. In other words, the pacing threshold is a fixed value.
False - the pacing threshold is unique to each person and it subject to change over the course of the day, with disease progression, drugs, and even posture. In other words, the pacing threshold is not a fixed value.
What is the electrical formula (energy = voltage (2) x time/resistance or E = V2T/R) really sayin gin regards to energy?
This formula really means that when you double the voltage, you quadruple the energy. Doubling the time (duration) will only double the energy consumed.
What is the generally accepted safety margin for pulse width?
3:1 safety margin is used for pulse width.
True/False - “Undersensing,” which refers to not sensing things that ought to have been sensed.
True
“Oversensing” leads to _______
underpacing
“Undersensing” leads to _______
overpacing
see image
see image
sensing is measured in what unit of measure?
Millivolts (mV)
True/False - To decrease sensitivity, decrease the millivolt setting.
False - To increase sensitivity, decrease the millivolt setting.
True/False - To decrease sensitivity, increase the millivolt setting
True
see images
see images
Describe the ‘alert period’ in regards to pacemaker timing
During the pacing or escape interval, there is a period of time during which the pacemaker can respond to sensed activity; this phase is appropriately named “the alert period.” During this time, the pacemaker can sense and will respond to any incoming signals of intrinsic cardiac activity. For most devices, the longest component of the pacing interval is the alert period.
Describe the ‘refractory period’ in regards to pacemaker timing
To prevent the pacemaker from responding to these signals (and to prevent a ventricular output from pacing into a T wave), the pacemaker or escape interval has a phase known as the “refractory period.” During this time, the pacemaker will not respond to any incoming signals.
For temporary pacing, what mode is used, synchronous or asynchronous?
Asynchronous. Although uncommon, it is possible to program a single-chambered pacemaker to pace asynchronously, i.e. to pace without sensing.
What is the main benefit of dual-chamber pacing?
AV synchrony, the properly timed and coordinated activity of the atria in relationship to the ventricles. the healthy heart provides 1:1 AV synchrony, meaning that every atrial contraction results in a corresponding ventricular contraction. When AV synchrony prevails, patients have good hemodynamics and an efficiently pumping heart.
True/False - Dual-chamber pacemakers provide AV synchrony by coordinating atrial activity with ventricular activity in such a way that 2:1
False - the ration is 1:1, not 2:1 in normal pacing conditions.
What happens if a P wave occurs during the atrial alert period?
It immediately terminates the atrial alert period, i.e. the alert period ends as soon as it has sensed what it has been looking for. Alert periods on both channels are precisely timed intervals. If the atrial alert period should expire or time out before it can sense a P wave, then the pacemaker will deliver an atrial output pulse. The atrial alert period can only terminate if intrinsic activity is sensed, that is, if a P wave is detected, or if the alert period times out and an atrial output pulse is delivered.
True/False - The purpose of refractory periods is to prevent the pacemaker from responding to inappropriate signals.
True - during these so-called refractory periods, the pacemaker will ignore incoming signals (or in some cases not even see them). The purpose of refractory periods is to prevent the pacemaker from responding to inappropriate signals.
A pacemaker can only do two things: _____ or ______.
1) pace
2) sense
In terms of tracing, AS means what?
Atrial Sense
In terms of tracing, VP means what?
Ventricular Pace
What does MTR stand for?
Maximum Tracking Rate. It defines the fastest rate at which the ventricles can be paced in response to intrinsic atrial activity.
see image pacing modes
DVI DDI VDD or DOO image
What are the five (5) recommended fundamental questions for interpreting basic paced ECGs?
1) What are the programmed settings of the pacemaker and are they consistent with what shows up in the rhythm strip?
2) is pacing occurring at the proper rate?
3) is there capture?
4) is there sensing?
5) what is the underlying rhythm?
see image rhythm strip over or under sensing
see image
Which clinical trial demonstrated that prophylactic defibrillator placement in patient with coronary artery disease can help improve mortality prior to hemodynamically significant events?
MADIT (MADIT I & MADIT II)
Which clinical trial broadened the application of defibrillators to patient with mild to moderate congestive heart failure (NYHA Class II or III), with ischemic and non-ischemic cardiomyopathy and left ventricular EF less than 36%?
SCD-HeFT
Which clinical trial demonstrated that bi-ventricular implantable defibrillators can improve both mortality (survival) and re-hospitalization rates in patients?
COMPANION
True/False - SCD-HeFT showed that ICD defibrillators decreases mortality when compared to amiodarone and placebo
True
True/False - The COMPANIOn trial was terminated early due to significant results that showed an ICD group of patients who experienced a reduction in deaths in the first year vs amiodarone or sotalol.
False - AVID trial.
True/False - The CTOPP extended study does not show a difference in cardiovascular death or stroke, or in total mortality, o r in stroke between patients implanted with ventricular or physiological pacemakers.
True
Which clinical trial studied post MI patients at high risk for VT, and showed an overall mortality reduction when compared to conventional medical therapy
MADIT II
Which clinical trial studied NYHA Class II or III heart failure patients with an EF <35% and showed an overall mortality reduction when compared to conventional medical therapy or placebo?
SCD-HeFT.
