3.3 Cardiac Arrhythmias, Conduction Blocks & Device Rhythms (Pacemakers/ICDs)

AACVPR CCRP Certified Cardiac Rehab Professional Exam

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1 Chapter 1: Introduction & Cardiac Rehabilitation Foundations

1.1 AACVPR CCRP Credential, Exam Specifications & Core Competencies 1.2 Phases of Cardiac Rehabilitation & Clinical Delivery Models 1.3 Interdisciplinary Team Roles, Clinical Scope of Practice & Safety

2 Chapter 2: Cardiovascular Anatomy, Physiology & Pathology

2.1 Cardiac Anatomy, Coronary Circulation & Hemodynamics 2.2 Atherosclerosis Pathogenesis, Acute Coronary Syndromes (ACS) & Revascularization 2.3 Heart Failure (HFrEF/HFpEF), Cardiomyopathies & Valvular Heart Disease 2.4 Electrical Interventions: Cardioversion, Catheter Ablation & Post-Procedure Rehabilitation

3 Chapter 3: Diagnostic Evaluation, ECG & Clinical Testing

3.1 Baseline Clinical Assessment & AACVPR Risk Stratification 3.2 12-Lead ECG Interpretation: Ischemia, Transmural Infarction & Conduction 3.3 Cardiac Arrhythmias, Conduction Blocks & Device Rhythms (Pacemakers/ICDs) 3.4 Graded Exercise Testing (GXT), Gas Exchange & Termination Criteria

4 Chapter 4: Patient-Centered Assessment: Education, Equity & Social Context

4.1 Learning Readiness: Health Literacy, Learning Styles & Communication Barriers 4.2 Social Determinants of Health, Culture & Spirituality in Cardiac Rehab 4.3 Sex- and Race-Based Differences in Cardiovascular Presentation & Outcomes 4.4 Substance Use Screening: Alcohol, Cannabis, Stimulants & Cardiac Risk

5 Chapter 5: Exercise Prescription & Aerobic Conditioning

5.1 FITT-VP Framework & Aerobic Exercise Intensity Calculation 5.2 Exercise Progression, Environmental Factors & Telemetry Monitoring Guidelines 5.3 High-Intensity Interval Training (HIIT) vs Moderate Continuous Training (MICT) 5.4 Home Exercise Program Design, Prescription & Independent Progression

6 Chapter 6: Exercise Physiology, Monitoring & Session Design

6.1 Health-Related Physical Fitness Components & Functional Capacity Testing 6.2 Acute Cardiovascular Responses to Aerobic Exercise: METs, Rate Pressure Product & VO₂ 6.3 Chronic Training Adaptations in Cardiac Patients 6.4 Structuring the Exercise Session: Warm-Up, Conditioning & Cool-Down 6.5 ECG Telemetry Setup: Skin Preparation, Electrode Placement & Artifact Troubleshooting 6.6 Pulse Oximetry, Exertional Desaturation & Supplemental Oxygen Titration

7 Chapter 7: Resistance, Flexibility & Exercise Safety

7.1 Resistance Training Guidelines, Hemodynamics & Sternal Precautions 7.2 Flexibility, Neuromotor Training & Special CR Populations 7.3 Exercise Contraindications, Adverse Signs/Symptoms & Emergency Protocols

8 Chapter 8: Physical Activity Counseling & Behavior Change

8.1 Physical Activity Guidelines, Sedentary Physiology & NEAT 8.2 Behavioral Change Theories: Transtheoretical Model & Social Cognitive Theory 8.3 Motivational Interviewing Principles & Resolving Ambivalence 8.4 SMART Goal Setting, Activity Tracking & Relapse Prevention

9 Chapter 9: Physical Activity Assessment & Real-World Activity Counseling

9.1 Physical Activity vs Exercise: Assessment Instruments, Logs & Wearables 9.2 Metabolic Requirements of Daily Life: Occupational, Recreational & Sexual Activity 9.3 Environmental & Situational Risk: Heat, Cold, Altitude, Air Quality & High-Risk Activities 9.4 Upper- vs Lower-Body Physiologic Demands & Modality Selection

10 Chapter 10: Hypertension & Blood Pressure Regulation

10.1 2017 ACC/AHA Hypertension Classification & Cardiovascular Risk 10.2 Antihypertensive Pharmacology & Exercise Hemodynamics 10.3 Exertional Blood Pressure Dynamics, Exertional Hypotension & Crisis 10.4 Home Blood Pressure Monitoring, Sodium Restriction & Lifestyle Interventions 10.5 Blood Pressure Measurement Technique, Device Validation & Renal Protection

11 Chapter 11: Diabetes Mellitus & Metabolic Regulation

11.1 Diabetes Pathophysiology, Diagnostic Criteria & Glycemic Targets 11.2 Antidiabetic Pharmacotherapy (Insulin, Sulfonylureas, SGLT2i, GLP-1 RA) 11.3 Exercise-Induced Hypoglycemia Management (Rule of 15) & Hyperglycemia 11.4 Diabetic Complications & Exercise Adaptations (Autonomic & Peripheral Neuropathy) 11.5 Blood Glucose Self-Monitoring, CGM Interpretation & Peri-Exercise Testing 11.6 Diabetic Foot Care, Skin Integrity & Footwear Assessment

12 Chapter 12: Blood Lipid Management & Atherosclerosis Prevention

12.1 Lipid Metabolism, Atherogenic Lipoproteins & Advanced Lipid Testing 12.2 Statin Therapy, Dosing Intensity & Secondary Prevention Targets 12.3 Non-Statin Pharmacotherapies & Statin-Associated Muscle Symptoms (SAMS)

13 Chapter 13: Medical Nutrition Therapy & Dietary Patterns

13.1 Nutritional Assessment & Macronutrient Guidelines in Cardiovascular Disease 13.2 Cardioprotective Dietary Patterns: Mediterranean, DASH & Plant-Based 13.3 Dietary Lipids, Sodium, Soluble Fiber & Plant Stanols/Sterols 13.4 Clinical Scope: CR Professional Counseling Boundaries vs RD/RDN Referral

14 Chapter 14: Body Composition & Weight Management

14.1 Anthropometric Assessment: BMI, Waist Circumference & Obesity Paradox 14.2 Behavioral Weight Management, Energy Balance & Caloric Deficits 14.3 Anti-Obesity Pharmacotherapy (GLP-1/GIP) & Bariatric Surgery Considerations

15 Chapter 15: Tobacco Cessation Interventions

15.1 Cardiovascular Pathophysiology of Tobacco, Nicotine & Secondhand Smoke 15.2 Clinical Cessation Frameworks: The 5 A's & 5 R's Models 15.3 Pharmacotherapy for Nicotine Dependence: NRT, Varenicline & Bupropion 15.4 Behavioral Counseling, Coping Strategies & Relapse Prevention

16 Chapter 16: Psychosocial Health, Screening & Behavioral Support

16.1 Psychosocial Risk Factors & Prognostic Impact in Heart Disease 16.2 Validated Screening Instruments: PHQ-9, GAD-7 & Administration 16.3 Evidence-Based Interventions: Stress Management, CBT Principles & Social Support 16.4 Crisis Protocols, Suicidal Ideation & Mental Health Referral Pathways 16.5 Psychotropic Pharmacology & Cardiac Safety 16.6 Sleep Disturbance, Chronic Pain & Somatic Comorbidity in Psychosocial Management

17 Chapter 17: Regulatory Compliance, Documentation & Program Outcomes

17.1 CMS Coverage Guidelines, Qualifying Diagnoses & Practitioner Supervision 17.2 Individualized Treatment Plan (ITP) Components, 30-Day Updates & Goals 17.3 AACVPR Outcome Domains & Program Certification Performance Measures 17.4 Program Certification, Quality Improvement & Medical Emergency Preparedness

3.3 Cardiac Arrhythmias, Conduction Blocks & Device Rhythms (Pacemakers/ICDs)

Key Takeaways Explain This Topic AI

Atrial fibrillation causes an irregularly irregular ventricular rhythm with fibrillatory f-waves, leading to the loss of the atrial kick and a 15% to 25% reduction in resting and exertional cardiac output.

Ventricular arrhythmias during exercise require immediate classification: non-sustained ventricular tachycardia (NSVT, 3+ consecutive PVCs lasting < 30 seconds) warrants exercise cessation and physician notification, whereas sustained VT (> 30 seconds or hemodynamic collapse) demands immediate emergency response and defibrillation.

Second-degree Mobitz Type II AV block and third-degree (complete) AV block represent infranodal conduction failure with severe risk of hemodynamic collapse, serving as absolute contraindications to exercise.

The NBG pacemaker code identifies device functions across positions: Position I designates chamber paced, Position II indicates chamber sensed, and Position III specifies response to sensing (e.g., DDDR paces and senses both atria and ventricles, inhibits/triggers, and modulates rate).

For patients with an implantable cardioverter-defibrillator (ICD), the peak exercise target heart rate must be programmed at least 10 to 20 beats/min below the lowest programmed tachycardia detection/therapy threshold to prevent inappropriate shocks.

Last updated: September 2026

3.3 Cardiac Arrhythmias, Conduction Blocks & Device Rhythms (Pacemakers/ICDs)

Continuous telemetry monitoring in cardiac rehabilitation requires swift rhythm discrimination. Clinicians must differentiate benign ectopy from life-threatening ventricular dysrhythmias, recognize progressive conduction system failure, and safely supervise patients with pacemakers and implantable cardioverter-defibrillators (ICDs).

Supraventricular Arrhythmias & Hemodynamic Compromise

Supraventricular arrhythmias arise above the bifurcation of the bundle of His, typically producing narrow QRS complexes ( < 0.12 s < 0.12\text{ s} < 0.12 s ).

1. Sinus Node Rhythms & Premature Atrial Contractions (PACs)

Sinus Bradycardia ( H R < 60 bpm HR < 60\text{ bpm} H R < 60 bpm ) : Common in endurance conditioning or beta-blockade; pathologic if symptomatic or failing to rise with exertion (chronotropic incompetence).

Sinus Tachycardia ( H R > 100 bpm HR > 100\text{ bpm} H R > 100 bpm ) : Exertional tachycardia is physiologic; resting tachycardia signals deconditioning, hypovolemia, anemia, or heart failure exacerbation.

Premature Atrial Contractions (PACs) : Ectopic atrial beats with abnormal P-wave morphology followed by a narrow QRS. Generally benign, but frequent PACs may trigger paroxysmal atrial flutter or fibrillation.

2. Atrial Flutter

Driven by a right atrial reentrant circuit (atrial rate 250 to 350 bpm ), atrial flutter produces classic "sawtooth" flutter ( F F F ) waves in leads II, III, aVF, and V 1 V_1 V 1 ​ . Conduction ratios include:

2:1 AV Conduction : Ventricular rate fixed at 150 bpm (any regular narrow-complex rhythm at 150 bpm warrants evaluation for atrial flutter).

4:1 AV Conduction : Ventricular rate regular at 75 bpm .

3. Atrial Fibrillation (AF)

Chaotic atrial activation (electrical rate 350 to 600 bpm ) with absent organized mechanical contraction. The ECG displays absent P waves, fibrillatory ( f f f ) baseline waves, and an irregularly irregular ventricular response .

Hemodynamic Consequences

In sinus rhythm, coordinated atrial systole ("atrial kick") contributes 15 % to 25 % 15\% \text{ to } 25\% 15% to 25% of left ventricular end-diastolic volume (up to 40 % 40\% 40% in non-compliant ventricles). AF eliminates the atrial kick, substantially diminishing stroke volume and cardiac output. A rapid ventricular response ( H R > 100 bpm HR > 100\text{ bpm} H R > 100 bpm ) curtails diastolic filling time, elevating atrial pressures and inducing exertional dyspnea or angina.

Thromboembolic Risk ( C H A 2 D S 2 -VASc CHA_2DS_2\text{-VASc} C H A 2 ​ D S 2 ​ -VASc )

Stroke risk is evaluated via C H A 2 D S 2 -VASc CHA_2DS_2\text{-VASc} C H A 2 ​ D S 2 ​ -VASc : Congestive Heart Failure (1), Hypertension (1), Age ≥ 75 \ge 75 ≥ 75 (2), Diabetes (1), Prior Stroke/TIA (2), Vascular Disease (1), Age 65–74 (1), Female Sex (1). Anticoagulation (DOACs or warfarin) is indicated for scores ≥ 2 \ge 2 ≥ 2 in men or ≥ 3 \ge 3 ≥ 3 in women.

Ventricular Arrhythmias & Clinical Management Protocols

Ventricular dysrhythmias originate below the bundle of His, producing wide ( Q R S ≥ 0.12 s QRS \ge 0.12\text{ s} QRS ≥ 0.12 s ), bizarre complexes with discordant T waves.

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1. Premature Ventricular Contractions (PVCs)

Patterns : Unifocal (uniform) vs Multifocal (multiple foci, higher ischemic risk); Couplets (two consecutive); Bigeminy (every other beat); Trigeminy (every third beat).

R-on-T Phenomenon : A PVC falling on the vulnerable downslope of the preceding T wave, risking degeneration into polymorphic VT or ventricular fibrillation.

Exercise Response : Isolated PVCs that suppress during warm-up are typically benign. PVCs appearing or multiplying with exertion indicate active ischemia, ventricular dysfunction, or electrolyte derangements.

2. Ventricular Tachycardia & Fibrillation Protocols

Non-Sustained Ventricular Tachycardia (NSVT) : Defined as ≥ 3 \ge 3 ≥ 3 consecutive ventricular beats at > 100 bpm > 100\text{ bpm} > 100 bpm lasting < 30 seconds < 30\text{ seconds} < 30 seconds without hemodynamic collapse. Immediate action: stop exercise, assess vitals, obtain a 12-lead ECG, and notify the medical director.

Sustained Ventricular Tachycardia (VT) : Persists for > 30 seconds > 30\text{ seconds} > 30 seconds or causes hemodynamic collapse. Action: stop exercise, activate emergency response, assess pulse. If pulseless, initiate CPR and attach an AED/defibrillator.

Ventricular Fibrillation (VF) : Chaotic, lethal undulating rhythm without identifiable QRS complexes or pulse. Immediate action: call Code Blue, initiate CPR, and deliver an immediate high-energy unsynchronized defibrillator shock (120–200 J biphasic).

Atrioventricular (AV) Conduction Blocks

AV Block Type Pathophysiology & Site ECG Characteristics Exercise Stability & Action

First-Degree AV Block Delayed AV nodal conduction Constant PR interval > 0.20 s > 0.20\text{ s} > 0.20 s ( 200 ms 200\text{ ms} 200 ms ); 1:1 AV conduction Benign; common with beta-blockers; exercise permitted

Second-Degree Mobitz I (Wenckebach) Progressive AV nodal fatigue Progressive PR lengthening until a P wave fails to conduct (dropped QRS) Usually benign and transient; monitor hemodynamics during exercise

Second-Degree Mobitz II Infranodal His-Purkinje block Constant PR interval in conducted beats; sudden intermittent non-conducted P waves Unstable; high risk of progression to complete AV block; absolute contraindication to exercise ; urgent pacemaker placement

Third-Degree (Complete) AV Block Complete AV dissociation Independent P waves ( 60 – 100 bpm 60\text{--}100\text{ bpm} 60 – 100 bpm ) and slow junctional ( 40 – 60 bpm 40\text{--}60\text{ bpm} 40 – 60 bpm ) or ventricular ( 20 – 40 bpm 20\text{--}40\text{ bpm} 20 – 40 bpm ) escape rhythm Medical emergency; severe hemodynamic collapse; absolute contraindication to exercise ; emergent temporary/permanent pacing

• Pacemakers and Implantable Cardioverter-Defibrillators (ICDs)
• NBG Pacemaker Code

Pacemaker modes are classified by a five-letter standard: Position I = Chamber Paced (A, V, D, O); Position II = Chamber Sensed (A, V, D, O); Position III = Response to Sensing (T, I, D, O); Position IV = Rate Modulation (R, O); Position V = Multisite Pacing (A, V, D, O).

DDDR Mode : Senses and paces both chambers, inhibits or triggers pacing as needed, and modulates heart rate using activity sensors (accelerometers).

Telemetry Appearance : Sharp vertical pacer spikes preceding P waves (atrial pacing) or wide QRS complexes (ventricular pacing). Clinicians watch for failure to capture, undersensing (spikes firing into intrinsic beats; R-on-T risk), and oversensing (inappropriate inhibition from muscle artifact).

ICD Exercise Safety Thresholds

ICDs detect ventricular tachyarrhythmias and deliver antitachycardia pacing (ATP) or defibrillator shocks.

Important

The 10-to-20 Beats/Min Safety Margin : The prescribed peak exercise target heart rate must be set at least 10 to 20 beats/min below the lowest programmed tachycardia detection threshold . Peak Exercise HR ≤ Lowest Programmed ICD Therapy Threshold − 10 to 20 bpm \text{Peak Exercise HR} \le \text{Lowest Programmed ICD Therapy Threshold} - 10\text{ to } 20\text{ bpm} Peak Exercise HR ≤ Lowest Programmed ICD Therapy Threshold − 10 to 20 bpm

Example : If an ICD detection threshold is programmed at 165 bpm 165\text{ bpm} 165 bpm , the patient's exercise heart rate ceiling must not exceed 145 to 150 bpm 145\text{ to } 150\text{ bpm} 145 to 150 bpm to avoid inappropriate shocks triggered by exertional sinus tachycardia.