Comprehensive Study Notes on Cardiac Rhythms and Dysrhythmias

Premature Ventricular Contractions (PVCs)

• PVCs occur more frequently in older adults and are a common epidemiological finding.
• Comorbidities associated with PVCs include heart disease, hypertension, and electrolyte imbalances.
• While young and otherwise healthy adults are just as likely to experience PVCs, manifestations and perfusion-related complications typically increase with age.

Clinical Presentation and Patient Experience

• PVCs are often asymptomatic.
• Symptomatic individuals may feel palpitations, described as the heart missing a beat.
• Other symptoms include lightheadedness, chest pain, and shortness of breath ($\text{SOB}$).
• Psychosocial impacts include increased anxiety, fear, and depression related to the unexpected onset and unknown treatment of the condition.

Diagnostics and Nursing Considerations

• Lab tests include checking electrolytes, specifically potassium ($K^+$) and magnesium ($Mg^{2+}$), to see if they are low.
• Hyperthyroid disease is assessed by checking thyroid levels.
• An ECG is used to determine the cardiac rhythm.
• A Holter monitor is utilized for continuous recording over a period of $24-48\,h$.
  • It typically uses $3-5$ leads and is portable.
  • It pairs with a patient journal where they can manually trigger a recording.
  • Modern versions consist of a small adhesive dot or button taped to the chest.

Treatment and Management

• Patients may need to alter strenuous activity or exercise routines if they become symptomatic.
• For those over the age of $55$, annual cardiac health screenings are recommended for early detection of heart disease.
• Medications include beta blockers or antiarrhythmic medications.
• Vital signs must be monitored continuously as dosages may be titrated; there is a risk of blood pressure and heart rate dropping into sinus bradycardia.
• Ablation may be considered as a treatment option.

Client Education

• Stop smoking and the use of illicit drugs.
• Restrict alcohol consumption.
• Reduce caffeine intake as some individuals may be sensitive to its effects on cardiac rhythm.

Premature Atrial Contractions (PACs)

• A PAC is an abnormal rhythm where the atrium contracts earlier than expected in a normal cardiac cycle.
• This occurs because of an early heart impulse from one of the two atrial chambers, often due to irritated arterial tissue firing an early electrical impulse.
• The PAC disrupts the normal space between the atrium and ventricle contracting; following a PAC, there is often a long delay before the next cycle begins.

Etiology and Risk Factors

• The specific cause is often unknown.
• Linked health conditions include myocardial infarction ($\text{MI}$), hypertension, diabetes, and congestive heart failure ($\text{CHF}$).
• Associated medications include digoxin, beta blockers, chemotherapy drugs, and some antidepressants.

Presentation and Lab Testing

• PACs are generally considered benign and may be asymptomatic or discovered inadvertently during a physical exam.
• Manifestations include palpitations, a fluttering sensation in the chest, and shortness of breath during physical activity.
• Diagnostic tests include an ECG and an echocardiogram to check for structural abnormalities.
• While no specific blood tests are ordered for PACs, electrolytes may be checked as a potential cause.
• Environmental factors to monitor include exercise routines, stress/anxiety levels, smoking, and alcohol use.
• Notably, caffeine does not have a known effect on PACs.

Management and Safety

• Clients are taught lifestyle modifications: reducing stress, avoiding alcohol and smoking, and monitoring for fatigue during exercise.
• Symptomatic individuals should use caution during physical activity to avoid exhaustion.

First-Degree Heart Block (AV Block)

• This condition involves a delay in transmitting an electrical signal through the right atrium to the AV node.
• The signal is not actually blocked but is slowed down or delayed.
• The diagnostic hallmark is a PR interval greater than $0.20\,s$.

Epidemiology and Risks

• Occurs in $1$ in every $1,000$ people.
• It is more common in individuals over the age of $40$.
• For those over $60$, the condition is twice as likely to occur in males.
• Causes include:
  • Cardiac disease (MI, coronary artery disease).
  • Electrolyte imbalances (hypokalemia or hypomagnesemia).
  • Antiarrhythmic medications.
  • Infections such as endocarditis, rheumatic fever, and COVID-19.
  • Autoimmune disorders including rheumatoid arthritis, lupus, and sarcoidosis.
• Athletes may experience first-degree heart block due to higher resting vagal tone and tolerance for slower heart rates.

Clinical Presentation and Safety

• Patients are often asymptomatic and can perform activities of daily living ($\text{ADLs}$).
• Symptomatic patients experience fatigue, dizziness, and shortness of breath; they may need to alternate rest periods with exercise.
• Safety concerns include a significant risk for falls due to dizziness.

Nursing Interventions and Education

• Monitor vital signs and ECG tracings regularly.
• Hold medications that prolong the PR interval and notify the physician.
• Environmental/lifestyle advice: dietary changes (high sodium, cholesterol, and triglycerides should be avoided), low cholesterol diet, avoiding excessive fatigue, and stopping smoking/alcohol.

Atrial Fibrillation (AFib)

• AFib is a common cardiac arrhythmia where the SA node does not fire appropriately, resulting in rapid, chaotic, and irregular impulses.
• The atrium quivers or "fibrillates" rather than performing a coordinated contraction.
• This leads to decreased cardiac output and ineffective blood flow to the ventricles.

Complications and Risks

• Blood Clots: Because the atrium is quivering, blood stays pooled. Pooled blood has a high risk for coagulation.
• Embolic Events: If the rhythm spontaneously converts or the heart pumps a clot out, it can lead to a stroke, pulmonary embolism ($\text{PE}$), or heart attack.
• Untreated AFib leads to higher incidences of heart failure and mortality.
• Anticoagulant therapy (e.g., heparin, warfarin) is mandatory but increases the risk of spontaneous bleeding.

Epidemiology and Comorbidities

• $33\,million$ people globally have AFib.
• There are over $750,000$ annual hospitalizations related to the condition.
• It is more prevalent in those over $65$ and those who are overweight or obese.
• Associated conditions: Hypertension, diabetes, hyperthyroidism, obstructive sleep apnea ($\text{OSA}$), COPD, kidney disease, and recovery from cardiac surgery.

Clinical Presentation

• P waves on an ECG are unidentifiable/indiscernible.
• Irregular apical pulse (checked at the $5^{th}$ intercostal space).
• Symptoms include hypotension, palpitations, chest discomfort, exertional fatigue, lightheadedness, and fainting.
• Weight gain and increased urination may be reported.

Diagnostics

• ECG: Shows indiscernible P waves between QRS complexes.
• Echocardiogram: Measures the size of atria and ventricles and valve health.
• Transesophageal Echocardiogram (TEE): A detailed ultrasound via the esophagus for high-quality heart images.
• Labs: CBC, creatinine, glucose, T3, T4, TSH, and INR for those on anticoagurants.

Management and Anticoagulation

• Cardioversion: Synchronized electrical shock delivered on the R wave to disrupt the irregular cycle. Used if the patient is unstable.
• Pharmacology: Beta blockers, calcium channel blockers, digoxin, and amiodarone.
• Bleeding Precautions: For patients on anticoagulants, use soft-bristle toothbrushes, electric razors, and avoid contact sports or high-risk activities.
• Antidote: Vitamin K is the antidote for vitamin K antagonist anticoagulants (like warfarin) to manage spontaneous bleeding.

Atrial Flutter

• Extremely similar to AFib, but the atrial quivering is slightly more pronounced, appearing as "saw-tooth" waves on an ECG.
• Atrial rates range from $240$ to $400\,bpm$.
• The rapid impulses are sent too quickly for the AV node to process effectively.

Etiology and Treatment

• Causes: Recent MI, post-op cardiac surgery, cardiomyopathy, pericarditis, and chronic conditions like hypertension or diabetes.
• Certain meds used for AFib (digoxin, amiodarone) can actually predispose a patient to atrial flutter.
• Treatment follows the AFib protocol: anticoagulants, antiarrhythmics, rate control (beta blockers, calcium channel blockers), synchronized cardioversion, or cardiac ablation.

Supraventricular Tachycardia (SVT)

• SVT is a rapid heart rate ranging from $100$ to $220\,bpm$ (or higher) with a narrow QRS complex.
• It often starts and ends abruptly without warning; it is also known as AV nodal reentrant tachycardia.
• Impulses originating from the AV node cause excessive excitability of atrial tissues.

Presentation and Hazards

• Hemodynamic instability: The ventricles do not dilate long enough to allow for proper blood filling.
• Minimal cardiac output leads to unstable blood pressure and poor perfusion.
• Symptoms: Shortness of breath, feeling of passing out, lightheadedness, and anxiety.
• Comorbidities: Pregnancy, chronic lung disease, coronary artery disease, and hyperthyroid disease.

Medical and Nursing Interventions

• Vagal Maneuvers: These target the vagus nerve (cranial nerve X) which connects the abdomen to the heart.
  • Valsalva Maneuver: Bearing down as if having a bowel movement.
  • Forceful coughing or gagging.
  • Carotid massage.
• Adenosine: Administered via IV as part of the treatment algorithm.
• Pharmacology: If maneuvers/adenosine fail, IV Cardizem or beta blockers are used.
• Nursing Care: Implement fall precautions and monitor vital signs/cardiac rhythm before, during, and after maneuvers.