IBHRE: Clinical Practice

Clinical Practice

Guidelines & Exam Blueprint

ACC/AHA/HRS: Device Guidelines ▲

Ref: 2023 IBHRE CCDS Exam Content Outline ▲

Pacemaker Indications

Definition
2018 ACC/AHA/HRS Guideline on BRADYCARDIA ▲

Definition
2018 ACC/AHA/HRS Guideline on BRADYCARDIA ▲

Bradycardia Evaluation Algorithm
Noted that sleep apnea is now recognized as one of the conditions that causes bradycardia.
For those who had infrequent symptoms, implantable cardiac monitor (ICM) is recommended.
2018 ACC/AHA/HRS Guideline on BRADYCARDIA ▲

Sinus Node Dysfunction Management
Pacemaker is indicated only in symptomatic patients. 2018 ACC/AHA/HRS Guideline on BRADYCARDIA ▲

Choices of Pacemaker in SND
For those with symptomatic SND that is short-lived or infrequent, single chamber ventricular pacing including leadless pacemaker may be adequate.
The risk of developing AV block after PPM is 3-35%, depending on underlying bundle branch conduction abnormalities. 2018 ACC/AHA/HRS Guideline on BRADYCARDIA ▲

Management of AV Block
Symptoms of severe 1st degree AV block (PR >0.30s) and Mobitz I are similar to those of pacemaker syndrome. The indication for PPM is driven by symptoms.
For those with infranodal block (Mobitz II, advanced, or complete AV block) not from reversible causes, PPM is indicated regardless of symptoms.
2018 ACC/AHA/HRS Guideline on BRADYCARDIA ▲

Choices of PPM in AV Block
In AV Block with LVEF<50% and expected frequent RV pacing (>40%), CRT or His-bundle pacing are preferred.
2018 ACC/AHA/HRS Guideline on BRADYCARDIA ▲

Physiologic Pacing for Bradycardia
For a patient with anticipated frequent RV pacing, CRT or CSP is a class 2a recommendation for LVEF<50% and class 2b for LVEF>50%
2023 HRS Guideline on CSP ▲

Lyme Carditis
Lyme carditis is one of the most common reversible causes of AV block.Approximately 40% of patients who are identified clinically require temporary pacing, but permanent atrioventricular block after antibiotic therapy is rare.
JACC 2019. ▲

PPM post TAVR
PPM is class I for persisted high-grade AVB or new alternating BBB.
New conduction abnormalities included transient high-degree AVB, PR prolongation, or axis change. In patients with pre-existing RBBB + new conduction abnormalities, PPM may be considered (IIa).
2021 ESC Guidelines for pacing & CRT ▲

Leadless Pacemaker
2021 ESC Guidelines for Cardiac Pacing ▲

Temporary Transvenous Paceamker
For a long term need, consider temporary pacemaker using exteriorized active fixation lead.
EP Europace, September 2013 ▲

ICD Indications

ICD for Secondary Prevention in Patients with Ischemic Heart Disease
Need to exclude reversible causes.
ICD candidacy determined by functional status, life expectancy, or patient preference. 2017 AHA/ACC/HRS Guideline for Sudden Cardiac Death ▲

ICD for Primary Prevention in Patients with Ischemic Heart Disease
Early ICD implantation may consider in those with pacing indication or syncope. 2017 AHA/ACC/HRS Guideline for Sudden Cardiac Death ▲

ICD for non-Ischemic Heart Disease
In Lamin A/C mutation, ICD may be beneficial in those with 2 or more risk factors (NSVT, LVEF<45%, non-missense mutation, and male sex). 2017 AHA/ACC/HRS Guideline for Sudden Cardiac Death ▲

ICD for Hypertrophic Cardiomyopathy
HCM is the most common cause of SCD in individuals <40 years of age. 2017 AHA/ACC/HRS Guideline for Sudden Cardiac Death ▲

ICD for Long QT syndrome
Beta blocker is the 1st line therapy for both primary and secondary prevention. Nadolol is the most favorable agent.
2017 AHA/ACC/HRS Guideline for Sudden Cardiac Death ▲

Drug Class	Examples
Antiarrhythmics	class Ia and class III
Psychotropic Medications	Haloperidol, Citalopram, Tricyclic Antidepressants
Antibiotics	Erythromycin, Azithromycin, Ciprofloxacin, Levofloxacin, Fluconazole
Antiemetics	Domperidone, Ondansetron
Others	Methadone

Commonly used QT-prolonging Medications
More complete list at crediblemeds.com or download pdf version here ▲

Avoid need for venous access.
May not achieve adequate sensing in all patients.
No ATP or continous pacing support.
May be appropriate in HCM, Brugada, and congenital heart patients.

Tetralogy of Fallot
The most common cyanotic congenital heart disease in grown-up adult. ▲

ICD in Adult Congenital Heart Disease
*High-risk features: prior palliative systemic to pulmonary shunts, unexplained syncope, frequent PVC, atrial tachycardia, QRS duration ≥180 ms, decreased LVEF or diastolic dysfunction, dilated right ventricle, severe pulmonary regurgitation or stenosis, or elevated levels of BNP.
2017 AHA/ACC/HRS Guideline for Sudden Cardiac Death ▲

CRT & Conduction System Pacing Indications

Indications for CRT Therapy
2022 ACC Guidelines for HF ▲

Benefits of CRT in LBBB varied by the duration of QRS. The benefit began in QRS>120ms and became clearer in QRS≥150ms.
Results from RAFT. Circ Heart Failure 2013. ▲

Benefits of CRT in non-LBBB is less than that of LBBB.
Results from RAFT. Circ Heart Failure 2013. ▲

Classification of LV Lead Position
Circulation 2011. ▲

Apical LV lead position was associated with higher incidence of HF or death compared to non-apical position.
Circulation 2011. ▲

Selective His bundle pacing (S-HBP) is easily recognized by an isoelectric interval (corresponding to the HV) between the pacing spike and QRS onset, whereas with non-selective HBP, a ‘pseudo-delta’ wave is observed due to capture of local myocardium.
2023 EHRA Consensus on CSP ▲

CSP in patients with pacing indication 2023 HRS Guidelines for CSP ▲

CSP in patients with HF 2023 HRS Guidelines for CSP ▲

Device Implantation: Anatomical Considerations

Subclavian Venous System
1. Cephalic vein is smaller and more superficial than Axillary vein.
2. Axillary vein is behind pectoralis major and minor.
3. After axillary vein leaves pectoralis minor, it becomes subclavian vein.
4. Subclavian vein is in both extra and intrathoracic region.
Heart Rhythm 2006. ▲

SUBCLAVIAN CRUSH SYNDROME
= damage of the leads from the subcutanous structures prior to venous entry
Subcutaneous structures = Costoclavicular ligament (#) and/or Subclavius muscle (*)
Damage can range from outer insulation to conductor to inner insulation to total transection

Extrathoracic subclavian/axillary vein puncture
A venogram has been performed from the left antecubital fossa (top-right panel). This shows the drainage into the cephalic vein, axillary vein, running over the first rib, and then into the subclavian vein.
Heart 2009;95:259-264. ▲

Landmark for Cephalic Vein
The cephalic vein lies on the deltopectoral groove (yellow) and is sometimes marked by a skin crease.
The deltopectoral groove is bordered by clavicle, deltoid muscle, and pectoralis major muscle.
howtopace.com ▲

Differences Venous Approached for CIED Implantations

Aspects	Subclavian	Cephalic	Axillary
Venous Character	Largest size	Small; may be tortuous	Large
Procedural Success	96%	76% steep learning curve, may require another access to accomodate all leads.	96% venogram and ultrasound can be utilized to guide the puncture.
Pneumothorax	1%	No risk	0-0.2%
Lead Failure	2.3%	1.1%	1.5%

JACC 2020 and JCE 2019

Anatomy of Right Atrium
Right Atrial Appendage is located at anterosuperior aspect of RA.
Terminal Crest or Crista Terminalis acts as a barrise of conduction.
Translation Research in Anatomy 2019. ▲

Triangle of Koch
is an important landmark for AV node. Translation Research in Anatomy 2019. ▲

Fluoroscopic Anatomy of AV node
2023 EHRA consensus on CSP. ▲

Anatomy of the heart chambers relevant for pacing
Right anterior oblique view (∼20°) of the heart. Note proximity of the tip (*) of the right atrial appendage (RAA) to the aortic root (Ao) and the right ventricle. The pacing lead is positioned on the mid-septum against the septo-marginal trabeculation (SMT) below the supraventricular crest (SVcrest), which forms the inferior border of the right ventricular outflow tract (RVOT). A noticeable «jump» can be seen as the lead is pulled back from the RVOT over these structures. ▲

Bachmann's Bundle
AKA interatrial bundle; connecting the right and left atria; considered to be the main pathway for interatrial conduction.
Cir Arrhythmia 2013. ▲

Anatomy of Coronary Sinus ▲

Tissue plane for appropriate device implantation
Most common: Subcutaneous pocket = below fat and above muscles. howtopace.com ▲

Device Implantation: Procedural Considerations

Preoperative Checklist
2021 EHRA consensus on optimal implantation techniques ▲

Preoperative Management of Anticoagulation and Antiplatelets
Hemetoma increases risk of infection. Uninteruppted oral anticoagulation is preferrable to heparin briding, as it reduces risk of hematoma.
For DOAC, incidence of hemaroma was not different between interupted and uninteruppted strategy.
2021 EHRA consensus on optimal implantation techniques ▲

Common Medications administered during Device Implantation

Roles	Examples
Antibiotics	Cefazolin, Cloxacillin, Vancomycin
Analgesic	Morphine derivatives such as fentanyl, morphine, meperidine (pethidine)
Sedative and Amnestic	Benzodiazepines (BZP; such as midazolam, diazepam)
Antidotes	Flumazenil (against BZP), Naloxone or Narcan (against Morphine group), Protamine (against heparin)

Timing of Antiobiotics before surgery
Preop antibiotic is recommended within 1 hr of skin incision.
Swiss Med Wkly. 2012;142:w13616 ▲

Sterile Techniques (1/2)

Tables draped as part of a sterile field are considered sterile only at the table level.
Anything out of your range of vision or below waist level is considered contaminated and unsterile.
If there are any questions or doubts about an object's sterility, the object should be considered unsterile.

Sterile Techniques (2/2)

Once a package is opened, a 2.5 cm (1 inch) border around the edge is considered unsterile.
A sterile object or field can become contaminated by lingering exposure to air.
A sterile barrier that has been compromised by punctures, tears or moisture has to be considered contaminated.

Typical Radiation Dose of some sources of radiation
The absolute lifetime risk of fatal cancer for an adult increases by 0.05% for every 10 mSv of exposure.
EP Europace 2014. ▲

Radiation Safety (1/2)

"ALARA" or "as low as reasonably achievable" Principle
Even if it is a small dose, if receiving that dose has no direct benefit, you should try to avoid it.
3 basic protective measures: time, distance, and shielding.

Ref: US Nuclear Regulatory Commission ▲

Radiation Safety (2/2)

The radiation Intensity is inversely proportional to the square of the distance. ▲

Concept of defibrillation threshold testing: DFT vs. ULV
The effects of an electrical shock vary as a function of the energy delivered. A low-energy shock, on the order of 1 Joule (J), delivered in the vulnerable period, can induce an arrhythmia. The upper limit of vulnerability corresponds to the lowest shock energy, which, when delivered during the ventricular vulnerable period, does not induce VF, a value that has been correlated with the defibrillation threshold.
cardiocases.com ▲

Conditions	DFT (Yes/No)	Class of Recommendation
Subcutanous	Yes	I
Initial left-pectoral, transvenous implantation with well-positioned RV lead and adequate sensing.	No	IIa
Right-pectoral implantation or generator change.	Yes	IIa
Contraindications to DFT*	No	III

*documented nonchronic cardiac thrombus, AF or atrial flutter without adequate systemic anticoagulation, critical aortic stenosis, unstable CAD, recent stroke or TIA, haemodynamic instability, or other known morbidities associated with poor outcomes.
2015 HRS/EHRA/APHRS/SOLAECE expert consensus statement on optimal implantable cardioverter-defibrillator programming and testing.

MRI in patients with CIEDs
MRI can be performed safely in non-MRI conditional devices as long as a number of precautions are taken.
2017 HRS Expert Consensus ▲

Complications

Complication: Pneumothorax
Risk factors for the development of a pneumothorax include: age >80 years, female sex, low BMI, chronic obstructive pulmonary disease, and subclavian vein puncture.
2021 EHRA Consensus ▲

Complication: Cardiac Tamponade
Cardiac tamponade perioperatively is due to lead perforation. It is strongly suggested by hemodynamic compromise and should be confirmed by echocardiography and treated with emergent pericardiocentesis.
2021 EHRA Consensus ▲

Perioperative Complications You Need to Know.

Complication	What is it?	What to do?
Cardiac Tamponade	Lead perforation causing blood leaking into the pericardiac space compressing the heart causing low cardiac output.	Echocardiogram to confirm. Pericardiocentesis to release the fluid.
Pneumothorax	Attempted subclavian puncture made a hole in the lung causing air leaks into the pleural space compressing the lung causing desaturation.	Air leaks into the pleural space compressing the lung causing desaturation.
Oversedation	Desaturation from hypoventilation or hypotension from vasodilatation.	Maintain airways, hydration, +/- antidotes.

Causes of Altered Impedance

Cir Arrhythmia 2020 ▲

Risk Factors for CIED Infection
The most important procedure-related risk factors are pocket hematoma, long-procedural time, and re-operation.
Staphylococcus aureus is the most common organism involved in acute CIED infections. 2019 EHRA Consensus on CIED infections ▲

Management Algorithm
Definite CIED clinical pocket/generator infection = generator pocket shows swelling, erythema, warmth, pain, and purulent discharge/sinus formation OR deformation of pocket, adherence and threatened erosion OR exposed generator or proximal leads.
2019 EHRA Consensus on CIED infections ▲

Lead Extraction Procedural Risk
- Major complications from lead extraction included death, cardiac arrest, pericardial tamponade, and cardiac perforation.
- Small diameter HV leads have low tensile strength limiting the traction force during extraction. Circulation EP 2018 ▲

Overt Septal Perforation of LBBAP Lead
In all cases of overt perforation, reposition is required. 2023 EHRA consensus on CSP. ▲

Micro-perforation of LBBAP Lead
No reposition or long-term anticoagulation is required. 2023 EHRA consensus on CSP. ▲

Other EP Testing/Procedures

Ambulatory Cardiac Monitoring
2020 CCS Guidelines on Syncope ▲

Test that creates changes in posture from lying to standing using to evaluate the cause of syncope.
May use adjunctive agents (Isoproterenol or nitroglycerine) to improve sensitivity.
Positive test = inducible presyncope or syncope with hypotension with or without bradycardia.
Should be considered when the cause of syncope is uncertain. Usually includes atypical presentations, distinguishing from epilepsy, non-hemodynamic collapse, or elderly with few clues in history.

2020 CCS Guidelines on Syncope

Electrophysiologic Study for Risk Stratification

Assess AV node/His-Purkineje function and differentiate between nodal or infra-hisian block.
Assess risk of ventricular arrhythmia in ICM, DCM, and ACHD.
Not useful in HCM, LQTS, SQTS, CPVT, Early repolarization syndrome, and those who are already indicated for ICD.

Indications for Electrophysiologic Study
Abbreviations: ICM: ischemic cardiomyopathy, DCM: dilated cardiomyopathy, ACHD: adult congenital heart disease, HCM: hypertrophic cardiomyopathy, LQTS: long QT syndrome, SQTS: short QT syndrome, CPVT: catacholinergic polymorphic VT.
Ref: 2017 SCD Guidelines ▲

Phrenic Nerve Injury after AF Ablation
Right-sided phrenic nerve injury is more common than left-sided injury. It is usually transient and resolves within 3 months. Permanent damage is <1%.
Cir Arrhythmia 2022 ▲

Ligament of Marshall
..is a fibrous band that connects the left atrium to the left pulmonary veins.
..is considered another source of foci in AF ablation.
Ann Thoracic Surgery 2025 ▲

Qs & As

Q1: A 76 year-old woman has shortness of breath 6 hours after undergoing a pacemaker. The pacemaker was done via cephalic route. On physical examination, her chest is clear, her BP is 80/50 mmHg, and the rhythm is AV paced at 70 bpm. Which of the following is the most appropriate management?

Administer of furosemide.
Administer of salbutamol.
Echocardiogram.
Chest X-ray.
Intravenous fluid.

Q1: The answer is...
Answer: c. Think of cardiac tamponade for hypotension and shortness of breath shortly after a device implantation. Pneumothorax is an unlikely complication for cephalic access. Heart failure, asthma exacerbation, or dehydration are possible but does not require an emergent diagnosis and treatment the same way cardiac tamponade does. ▲

Q2: Tracings from subcutaneous ICD ▲

Q2: A 48 y/o woman underwent implantation of a subcutaneous implantable cardioverter-defibrillator (ICD) for primary prevention of sudden death. She presented 3 months later for a routine ICD device interrogation. Her device setting and presenting rhythm are shown in the figure (a). Review of her stored electrograms (b) showed an untreated episode several weeks earlier. Which of the following is the next best step?

Schedule follow-up for device interrogation in 3 months.
Schedule the patient for a procedure to reposition the subcutaneous ICD lead.
Change the sensing configuration to an another vector.
Perform an exercise stress test.

Q2: The answer is...
Answer: d. At presentation, the patient is in sinus rhythm. At the programmed sensing configuration, each QRS complex is sensed appropriately. Thus, changing the sensing vector empirically to another configuration would not be indicated. The stored electrogram demonstrates clear evidence of a change in QRS morphology associated with T-wave oversensing in the initial portion of the tracing. The electrogram by the end of the tracing is sensed appropriately and resembles the electrogram obtained at the patient’s device interrogation on presentation. Since the device detected the rhythm as a ventricular arrhythmia, simply ignoring the observation would not be suggested. On the other hand, it is premature to consider repositioning the ICD lead. T wave oversensing is by far the most common cause of oversensing in the subcutaneous ICD and this is typically evaluated by ETT and changing the sensing vector. The most likely explanation is that the patient develops a rate-related bundle branch block during which the current programmed sensing configuration cannot adequately distinguish between QRS complexes and T waves. Thus, an exercise stress test will be useful to optimize the sensing configuration using a template acquired during exercise when the rate related QRS morphology can be replicated. ▲

Q3

Dextrocardia
Image flipped from L to R
Mustard Operation
Persistent left superior vena cava
Arterial implantation

Q3: The answer is...
Answer: d. Left SVC drains through coronary sinus and into RA and RV. ▲

Q4: An 82-year-old Caucasian male with ischemic cardiomyopathy, LVEF 0.10, status/post single-chamber ICD, progressive renal impairment, and 3 hospitalizations over the prior calendar year is re-hospitalized again. His device is interrogated and noted to be nearing end-of-life. The patient and family express an interest in proceeding with less aggressive care. Which of the following is the best approach to management of the ICD?

Selective inactivation of shock therapies while maintaining back-up ventricular pacing.
Elective generator change.
Upgrade to a CRT-D.
Electrophysiological study to evaluate for placement of an atrial lead.

Q4: The answer is...
Answer: a. End-of-life care
The decision to inactivate the shock function of a defibrillator needs to take into account patient preferences and overall prognosis, especially when heart failure symptoms have progressed despite optimal medical therapy. ACC/AHA guidelines suggest that a reasonable prognosis for survival of at least 1 year applies to de novo implants; the same applies to generator changes. ▲

Q5: A 70 year-old woman undergoes AV node ablation and CRT implantation for chronic AF and poor LVEF. Which of the following is the most likely reason for setting the initial lower rate of the device to 90 bpm?

To improve cardiac output.
To regularize ventricular rate.
To avoid ventricular tachycardia.
To enhance biventricular pacing.
To improve ventricular remodelling.

Q5: The answer is...
Answer: c. Rapid V pacing to prevent torsades.
Sudden death secondary to torsades de pointes or ventricular fibrillation has been reported after AV junction ablation. This outcome is possibly related to increased dispersion of ventricular refractoriness produced by sudden heart rate slowing and ventricular pacing. After ablation, the ventricular pacing rate is usually set between 90 bpm and 100 bpm and then gradually tapered over several months. ▲

Q6: During implantation of a pacemaker, an 80 year-old woman has back pain from lying on the operating table. After Fentanyl 50 mcg is administered, the symptoms resolve. Ten minutes later, Oxygen saturation drops to 85% with an end-tidal carbon dioxide of 50 mmHg, bradycardia, and hypotension.
Which of the following is the most appropriate therapy?

Atropine 1 mg
Dopamine drip
50% Oxygen via face mask
Flumaxenil 0.2 mg
Naloxone 0.4 mg

Q6: The answer is...
Answer: E.
Drop in Oxygen saturation and rise in CO2 after fentanyl compatible with hypoventilarion due to narcotic intoxication ▲

Q7: In children required pacing support, what is/are the advantage of epicardial lead over endocardial lead?

Lower chronic pacing threshold
Lower risk of lead failure
Preserves venous access
All of the above

Q7: The answer is...
Answer: c. Epicardial lead implantation requires sternotomy or thoracotomy or subxiphoid approach, and is associated with higher chronic stimulation threshold, higher lead failures and fractures, and early depletion of battery life.
However, it preserves the venous access for future use for children.

Ann Pediatr Cardiol. 2013.

▲

Q8: A primary prevention implantable cardioverter–defibrillator (ICD) is most strongly indicated in which of the following patients?

A male patient with syncope, QTc 440 ms, and LQT1 genotype not previously treated with beta-blockers.
A 20 year-old patient with syncope, NSVT, and diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC), including cardiac magnetic resonance imaging (MRI).
A 40 year-old asymptomatic patient with newly diagnosed nonischemic dilated cardiomyopathy (DCM), left ventricular ejection fraction (LVEF) 35%.
A 30 year-old patient without structural heart disease, with symptomatic monomorphic ventricular tachycardia [left bundle branch block morphology, right inferior axis, precordial R-wave transition in V3].

Q8: The answer is...
Answer: b.
a - Beta-blockers are the first-line therapy for LQT1.
c - ICD is indicated in DCM with LVEF ≤35% and symptomatic heart failure, but not in asymptomatic patients who has not been adequately medicated.
d - ICD is not indicated in patients without structural heart disease and monomorphic VT. Ablation is the first-line therapy for this patient. ▲

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Heart Rhythm Box is a collection of web-paged style presentations in clinical cardiac electrophysiology topics. The page is created mainly for educational purpose. I believe that presentations should be more interactive and easily accessible. No need to register or download. You can access everything at your fingertips.

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t' Thon, the screen name of the author, is a novice web developer, a wine enthusiast, and a cardiac eletrophysiologist by training.

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