Alterations in Cardiovascular Function & Perfusion

Cardiovascular Anatomy and Physiology Overview

• Heart Location and Anatomical Landmarks:

  • Situated in the mediastinal area of the chest cavity, positioned between the sternum, spinal cord, and lungs.

  • The apex, which serves as the point of maximal impulse (PMI), is located at the 5th intercostal space along the midclavicular line.

• Layers of the Heart:

  • Endocardium: The innermost layer composed of epithelial tissue; lines the internal cardiac chambers and heart valves.

  • Myocardium: The thickest and middle layer of the heart wall; composed of muscular tissue responsible for cardiac pumping activity.

  • Epicardium: The external serous layer that protects the outer heart surface.

  • Pericardium: The external fibrous sac surrounding the heart, consisting of two sub-layers:

    • Visceral Layer: Directly covers the outer cardiac surface.

    • Parietal Layer: Lines the pericardial sac and anchors the heart by attaching to the great vessels, diaphragm, sternum, and vertebral column.

• Heart Chambers:

  • Divided into 4 distinct chambers: Right Atrium (RA), Right Ventricle (RV), Left Atrium (LA), and Left Ventricle (LV).

  • Atria: Superior chambers responsible for receiving blood returning from the body and lungs.

  • Ventricles: Inferior chambers that receive blood from the atria and pump it outward into the pulmonary and systemic circulations.

  • Septum: Muscular wall that separates the right side (RA and RV) from the left side (LA and LV) of the heart.

• Heart Valves:

  • Atrioventricular (AV) Valves:

    • Include the Mitral (Bicuspid) valve and the Tricuspid valve.

    • Positioned between the atria and the ventricles.

    • During diastole, the mitral valve closes; during systole, the tricuspid valve closes.

  • Semilunar Valves:

    • Include the Pulmonic valve and the Aortic valve.

    • Positioned between the RV and the pulmonary artery, and between the LV and the aorta, respectively.

• Vascular System and Coronary Circulation:

  • Composed of arteries, veins, and capillaries, each exhibiting distinct structural and functional roles.

  • Coronary arteries deliver oxygenated blood flow directly to the myocardium via the Right Coronary Artery (RCA) and Left Main Coronary Artery (LMCA).

  • Left Main Coronary Artery Branches:

    • Left Anterior Descending (LAD) Artery: Supplies blood flow to the anterior wall of the left ventricle.

    • Circumflex Artery: Supplies blood flow to the left lateral side, including the left atrium and the posterior-lateral aspect of the left ventricle.

  • Right Coronary Artery Branches:

    • Passes along the right side of the heart and branch into the marginal artery and posterior descending artery.

    • Marginal Artery: Supplies blood to the lateral right side of the heart.

    • Posterior Descending Artery: Supplies blood to the posterior aspect of the heart.

• Cardiac Electrophysiology:

  • Sinoatrial (SA) Node: Located in the right atrium; functions as the primary intrinsic pacemaker setting the rate and rhythm of the heart.

  • Atrioventricular (AV) Node: Receives electrical impulses from the SA node; introduces a brief delay in conduction to allow the atria to fully contract and empty blood into the ventricles.

  • Bundle of His: Receives impulses from the AV node and bifurcates into the Right and Left Bundle Branches within the interventricular septum, directing impulses toward the RV and LV.

  • Purkinje Fibers: The terminal conduction network that distributes electrical impulses throughout the ventricular myocardium, resulting in ventricular contraction.

Hemodynamic Principles and Calculations

• Cardiac Cycle:

  • Consists of 2 alternating phases: Systole (the contraction phase) and Diastole (the relaxation phase).

  • One complete cardiac cycle corresponds to 1 full heartbeat.

• Cardiac Output (CO):

  • Defined as the total volume of blood ejected from a ventricle per unit time, expressed in liters per minute ($\text{L/min}$).

  • Dependent on intrinsic cardiac function, the vascular system, and venous return volume.

  • Typical normal baseline CO ranges between $5\,L/min$ and $6\,L/min$, fluctuating based on metabolic demand.

  • Calculated using the standard formula:         $CO = SV \times HR$

  • Factors directly influencing CO include vasoconstriction, arterial compliance, and arterial pressure (afterload).

• Stroke Volume (SV):

  • Defined as the specific volume of blood ejected by a ventricle during a single heartbeat.

  • Governed by three distinct physiological variables: preload, afterload, and myocardial contractility.

• Preload:

  • The degree of ventricular myocardial muscle stretch present at the end of diastole.

  • Ventricular volume reaches its peak at end-diastole, creating the maximum stretch on myocardial fibers.

  • Quantitatively measured using Pulmonary Capillary Wedge Pressure (PCWP).

• Afterload:

  • The resistance or pressure that the ventricles must generate to overcome vascular resistance and eject blood into the peripheral circulation.

  • Directly related to systemic arterial blood pressure and vascular vessel diameter.

• Contractility:

  • The intrinsic force generated by the myocardium during contraction.

  • Enhanced (increased) by Sympathetic Nervous System (SNS) stimulation and positive inotropic agents.

  • Depressed (decreased) by tissue hypoxia and negative inotropic agents.

Cardiac Sounds and Auscultation Findings

• Normal Heart Sounds:

  • S1 (First Heart Sound / "Lub"): Produced by the closure of the mitral and tricuspid atrioventricular valves at the onset of systole.

  • S2 (Second Heart Sound / "Dub"): Produced by the closure of the aortic and pulmonic semilunar valves at the onset of diastole.

• Abnormal Heart Sounds:

  • S3 and S4: Extra heart sounds indicative of altered ventricular compliance or fluid overload states.

  • Murmurs: Auscultated as a "whooshing" sound caused by turbulent blood flow moving across normal or structurally abnormal cardiac valves.

    • Systolic Murmurs: Heard specifically between S1 and S2.

    • Diastolic Murmurs: Heard specifically between S2 and S1.

  • Pericardial Friction Rub: Auscultated as a distinct high-pitched "grating" sound, typically heard best along the left sternal border; indicates pericardial inflammation.

Cardiac Electrophysiology and ECG Analysis Protocols

• Electrocardiogram (ECG/EKG) Fundamentals:

  • Non-invasive recording of the heart's electrical activity over time.

  • Depolarization: The electrical impulse activation triggering heart muscle contraction.

  • Repolarization: The electrical recovery phase leading to heart muscle relaxation.

• Components of the Cardiac Cycle on ECG:

  • Isoelectric Line: The flat baseline reading corresponding to electrical quiescence.

  • P Wave: Represents SA node firing and atrial depolarization.

  • PR Interval: The time measurement spanning from the start of atrial depolarization to the start of ventricular depolarization.

  • QRS Complex: Represents the time required for ventricular depolarization.

  • ST Segment: Represents the period between ventricular depolarization and the onset of ventricular repolarization. Elevation above baseline is diagnostic of ST-Elevation Myocardial Infarction (STEMI).

  • T Wave: Represents ventricular repolarization (may not always be clearly visible in every lead).

  • QT Interval: Represents the total duration of both ventricular depolarization and ventricular repolarization.

• Heart Rate Calculation Method:

  • Count the total number of QRS complexes within a $6\text{-second}$ ECG strip.

  • Multiply the counted number of complexes by $10$ to determine the total heart rate in beats per minute ($bpm$ or $\text{beats/min}$).

• Systematic 9-Step ECG Interpretation Method:

  1. Calculate heart rate.

  2. Determine if the heart rhythm is regular or irregular.

  3. Assess for the presence and uniformity of P waves.

  4. Measure the PR interval duration.

  5. Measure the duration of the QRS complex.

  6. Assess the ST segment for elevation or depression.

  7. Observe for morphologic changes in the T wave.

  8. Measure the length of the QT interval.

  9. Formulate an accurate overall rhythm interpretation.

• Normal ECG Reference Ranges:

  • Heart Rate: $60\text{ to }100/min$

  • Rhythm: Regular

  • P Waves: One uniform P wave preceding every QRS complex

  • PR Interval: $0.12\text{ to }0.20\,s$

  • QRS Complex: $0.06\text{ to }0.10\,s$ (must be strictly $< 0.12\,s$)

  • ST Segment: Isoelectric; no ST elevations or inversions

  • QT Interval: Varies according to age and biological sex:

    • Prepuberty: Less than $0.45\,s$

    • Postpubertal Males: Less than $0.46\,s$

    • Postpubertal Females: Less than $0.47\,s$

Normal Sinus Rhythm (NSR) Characteristics

• Diagnostic Criteria:

  • Heart Rate: $60\text{ to }100/min$

  • Rhythm: Strictly regular

  • P Waves: One consistently shaped P wave present prior to every QRS complex

  • PR Interval: Duration measures strictly between $0.12\text{ to }0.20\,s$

  • QRS Complex: Duration measures strictly between $0.06\text{ to }0.10\,s$

Sinus Bradycardia: Pathology, Clinical Manifestations, and Nursing Management

• ECG Diagnostic Criteria:

  • Heart Rate: Falls below $60/min$

  • Rhythm: Regular

  • P Waves: One consistently shaped P wave present prior to every QRS complex

  • PR Interval: Measures between $0.12\text{ to }0.20\,s$

  • QRS Complex: Measures between $0.06\text{ to }0.10\,s$

• Clinical Presentation and Health Impact:

  • Clients may present as entirely asymptomatic or severely symptomatic.

  • Symptomatic manifestations include fatigue, progressive shortness of breath, dizziness, chest pain, near-syncope, and acute mental status changes.

  • Primary safety risk: High risk for patient falls secondary to decreased cerebral perfusion.

• Pharmacological and Etiological Drivers:

  • Medications Causing Bradycardia: Parasympathomimetics (acetylcholine), Beta-blockers (e.g., metoprolol), Digitalis glycosides (e.g., digoxin), Calcium channel blockers (e.g., diltiazem), Antiarrhythmics (e.g., amiodarone), Chemotherapy agents (e.g., thalidomide), and Lithium.

  • Diagnostic Testing Required: Serum electrolyte panel, thyroid hormone panel (TSH/T4), serum troponin, along with blood and urine toxicology screens.

  • Patient Assessment History: Physical activity frequency/intensity, toxin/drug exposures, tick bite exposure (Lyme disease), systemic medical conditions (hypothyroidism, eating disorders).

• Nursing Process Implementation:

  • Recognize Cues (Assessment): Perform a focused assessment evaluating signs of reduced cardiac output (dizziness, chest pain, near-syncope, altered mental status, dyspnea) and identify predisposing risk factors.

  • Analyze Cues (Analysis): Obtain pulse rates and analyze continuous ECG waveforms.

  • Prioritize Hypotheses (Analysis): Categorize the client as hemodynamically stable or unstable.

  • Generate Solutions (Planning): Evaluate if cardiac output is sufficient for vital organ tissue perfusion; plan continuous vital sign/ECG monitoring, fluid administration, or cardiac pacing.

  • Take Action (Implementation):

    • Implement fall precautions for all symptomatic clients.

    • Maintain continuous vital signs and cardiac rhythm monitoring.

    • Insert a peripheral venous catheter (saline lock) anticipating intravenous fluid delivery.

    • Asymptomatic Clients: Maintain close clinical observation.

    • Unstable Clients: Administer IV Atropine $1\,mg$ every $3\text{ to }5\text{ minutes}$ up to a maximum cumulative dose of $3\,mg$. If the client remains unstable and symptomatic, prepare for immediate temporary transcutaneous pacing.

  • Evaluate Outcomes (Evaluation): Goal is to stabilize the heart rate above $60\,bpm$ while maintaining continuous telemetry monitoring.

Sinus Tachycardia: Pathology, Clinical Manifestations, and Nursing Management

• ECG Diagnostic Criteria:

  • Heart Rate: Greater than $100\,bpm$ (typically ranging from $>100\text{ to }<150\,bpm$)

  • Rhythm: Regular

  • P Waves: One consistently shaped P wave before every QRS complex

  • PR Interval: Measures between $0.12\text{ to }0.20\,s$

  • QRS Complex: Measures between $0.06\text{ to }0.10\,s$

• Clinical Presentation and Health Impact:

  • Symptomatic clients present with heart rates above $100\,bpm$ accompanied by palpitations, lightheadedness, dizziness, elevated body temperature, chest pain, or dyspnea.

  • Fall risk is increased; fall prevention protocols must be initiated.

  • Precipitating factors include recent infections, chronic medical disorders, physical stress, acute pain, anxiety, and specific drug effects.

• Nursing Process Implementation:

  • Recognize Cues (Assessment): Assess for signs of hemodynamic instability: elevated respiratory rate, dyspnea, hypotension, decreased level of consciousness, chest pain, decreased urine output, and signs of dehydration.

  • Analyze Cues (Analysis): Analyze heart rate trends and ECG tracing to establish hemodynamic stability status.

  • Prioritize Hypotheses (Analysis): Determine the precise underlying physiological cause driving the sinus tachycardia.

  • Generate Solutions (Planning): Establish a clinical plan to ensure essential tissue perfusion.

  • Take Action (Implementation):

    • Instruct symptomatic clients to reduce physical activity intensity and perform positional changes slowly.

    • Teach and assist with vagal maneuvers.

    • Ensure functioning IV access (saline lock).

    • Implement non-pharmacological interventions to treat fever, pain, stress, fear, or anxiety.

    • Administer prescribed medications: IV Adenosine or Beta-blockers (e.g., metoprolol).

    • Prepare for Catheter Ablation if indicated to destroy hyper-excitable cardiac tissue cells causing elevated rates.

  • Evaluate Outcomes (Evaluation): Maintain continuous monitoring of vital signs and heart rate responses.

Premature Ventricular Contractions (PVCs): Etiology, Patterns, and Clinical Management

• Pathophysiology and ECG Features:

  • Occur when early electrical impulses originate from ectopic, irritated ventricular myocardial cells prior to the next expected SA node impulse.

  • The ectopic QRS complexes appear prematurely in the cardiac cycle and display a abnormally wide, bizarre morphology compared to normal QRS complexes.

• ECG Presentation Patterns:

  • Bigeminy: Every second complex is a premature ventricular contraction ($\text{every other complex} = \text{PVC}$).

  • Trigeminy: Every third complex is a premature ventricular contraction ($\text{every 3rd complex} = \text{PVC}$).

• Etiology and Contributing Factors:

  • Hypertension, myocardial infarction (MI), cardiomyopathy, ventricular tachycardia, chronic obstructive pulmonary disease (COPD), pulmonary hypertension, sleep apnea, electrolyte disturbances, thyroid disorders, caffeine sensitivity, nicotine use, alcohol consumption, and illicit drug use.

• Clinical Presentation and Diagnostics:

  • Many clients remain completely unaware of PVCs; symptomatic clients report palpitations, lightheadedness, chest pain, or shortness of breath.

  • Laboratory Testing: Blood tests cannot detect PVCs directly but evaluate underlying triggers: serum potassium levels, serum magnesium levels, and thyroid panels.

  • Diagnostic Modalities: standard 12-lead ECG or continuous Holter monitor to analyze the frequency, pattern, and timeline of ectopic events.

• Nursing Process Implementation:

  • Recognize Cues (Assessment): Palpate peripheral pulses, auscultate apical heart sounds, gather timelines of patient symptoms, and document current chronic health conditions and complete medication lists.

  • Analyze Cues (Analysis): Examine ECG strips to identify PVC frequency/patterns; evaluate lab values for electrolyte abnormalities.

  • Prioritize Hypotheses (Analysis): Identify underlying pharmacological/physiological triggers and stabilize client condition.

  • Generate Solutions (Planning): Maintain adequate cardiac output; prepare for intravenous electrolyte repletion if deficiencies are identified.

  • Take Action (Implementation): Address modifiable triggers: advise smoking cessation, eliminate illicit drug use, reduce caffeine consumption, minimize alcohol, and replace depleted electrolytes.

  • Evaluate Outcomes (Evaluation): Monitor for improvement, deterioration, or unchanged ectopic activity.

• Pharmacological and Invasive Treatments:

  • Medications: Beta-blockers, Class IC antiarrhythmics (Flecainide, Propafenone), Class III antiarrhythmics (Amiodarone).

  • Catheter Ablation: Recommended when antiarrhythmic pharmacotherapy proves ineffective after a $30\text{-day}$ trial.

Premature Atrial Contractions (PACs): Etiology, Clinical Features, and Nursing Interventions

• Pathophysiology and Characteristics:

  • Benign cardiac rhythm events where irritated atrial tissue discharges an early electrical impulse before the next scheduled SA node contraction.

  • Exact etiology is unknown, but atrial irritability is commonly induced by underlying structural or metabolic alterations such as MI, HTN, DM, or Congestive Heart Failure (CHF).

  • Medication Triggers: Digoxin, beta-blockers, chemotherapy agents, and certain antidepressants.

  • Epidemiologically observed most frequently in pediatric/infant populations and older adults.

• Clinical Presentation and ECG Features:

  • Usually benign, asymptomatic, and poses no direct safety threat; often identified incidentally during routine physical examinations.

  • Symptomatic clients may report a brief "fluttering" feeling in the chest.

  • ECG Morphology: Underlying rhythm is typically normal; the P wave associated with the PAC may be abnormal, hidden in the preceding T wave, or unidentifiable; the PR interval of the premature beat is shortened ($< 0.12\,s$) or unmeasurable.

• Nursing Process Implementation:

  • Recognize Cues (Assessment): Review chronic disease history, medication lists, and subjective reports of palpitations.

  • Analyze Cues (Analysis): Analyze telemetry strips to calculate the exact frequency and count of PACs.

  • Prioritize Hypotheses (Analysis): Pinpoint specific lifestyle or disease triggers.

  • Generate Solutions (Planning): Ensure cardiac output remains adequate to maintain systemic organ perfusion.

  • Take Action (Implementation): Provide clinical reassurance; assist with lifestyle alterations; administer beta-blockers if clinically indicated.

  • Client Guidance: Advise the client to contact their healthcare provider if chest fluttering or dyspnea interferes with activities of daily living (ADLs).

  • Evaluate Outcomes (Evaluation): Classify status as improved, worsened, or unchanged.

First-Degree Heart Block: Conduction Delay and Nursing Care

• Pathophysiology and ECG Findings:

  • Occurs when conduction through the AV node is abnormally delayed or prolonged during impulse transmission from the right atrium to the ventricles.

  • It does not involve a complete electrical block; it represents a slowing or delay of conduction.

  • Pathognomonic ECG Finding: PR interval is consistently prolonged greater than $0.20\,s$ ($\text{PR interval} > 0.20\,s$).

• Etiological and Contributing Factors:

  • Associated with dietary intake high in sodium, cholesterol, or saturated triglycerides.

  • Can be induced by medications that slow AV nodal conduction.

• Nursing Process Implementation:

  • Recognize Cues (Assessment): Obtain past medical history, audit complete medication lists, record vital signs, auscultate heart sounds, and analyze ECG tracings.

  • Analyze Cues (Analysis): Measure exact PR interval durations across multiple cardiac cycles.

  • Prioritize Hypotheses (Analysis): Identify medications or conditions precipitating the AV conduction delay.

  • Generate Solutions & Take Action (Implementation):

    • Implement fall precautions.

    • Withhold and discontinue medications identified as causing PR interval prolongation.

    • Educate the client on lifestyle modifications: adopt a low-cholesterol diet, avoid excessive physical fatigue, abstain from smoking, and eliminate alcohol intake.

  • Evaluate Outcomes (Evaluation): Evaluate rhythm for improvement, worsening, or stability.

Atrial Fibrillation (A-Fib): Pathophysiology, Diagnostics, Complications, and Management

• Pathophysiology:

  • A common cardiac dysrhythmia resulting from failure of the SA node to act as the primary pacemaker.

  • Multiple ectopic foci throughout the atria fire rapid, chaotic, and irregular electrical impulses simultaneously.

  • Prevents effective atrial systole (contraction), leading to blood stasis within the atria, reduced stroke volume, and decreased overall cardiac output.

• Complications:

  • Stagnant blood within the atria forms mural thrombi (blood clots).

  • Embolization of atrial thrombi into systemic circulation can cause embolic strokes or severe ischemic organ damage to the brain, lungs, kidneys, or visceral vascular beds.

• Clinical Presentation:

  • Clients may present asymptomatic or severely impaired.

  • Signs and symptoms: Irregular pulse, hypotension, palpitations, elevated heart rate, chest discomfort, shortness of breath (occurring at rest or during exertion), exertional fatigue, anxiety, dizziness, lightheadedness, syncope, peripheral edema/weight gain, and decreased urinary output.

  • Clinical manifestations frequently restrict the ability to perform basic ADLs.

• Laboratory and Diagnostic Evaluation:

  • Blood Diagnostics: Serum Thyroid Stimulating Hormone (TSH), Thyroxine ($T_4$), Complete Blood Count (CBC), Serum Creatinine, Blood Glucose, and International Normalized Ratio (INR).

  • Transthoracic Echocardiogram (TTE): Measures structural atrial and ventricular dimensions and estimates ejection fraction.

  • Transesophageal Echocardiogram (TEE): Provides high-resolution imaging to detect micro-thrombi localized within the left atrium/left atrial appendage prior to cardioversion.

  • ECG Features: Irregularly irregular ventricular rhythm; absence of discrete P waves (replaced by fibrillatory atrial activity); ventricular rate may be controlled ($60\text{ to }100/min$) or elevated ($100\text{ to }200/min$).

  • Rapid Ventricular Response (RVR): Defined as Atrial Fibrillation presenting with a concurrent ventricular response rate exceeding $100/min$ ($> 100/min$).

• Nursing Process Implementation:

  • Recognize Cues (Assessment): Auscultate heart sounds, take blood pressure, assess peripheral pulses, measure for a pulse deficit (difference between apical heart rate and peripheral pulse rate), and interpret ECG strips.

  • Analyze Cues (Analysis): Screen ECG for rhythm changes and evaluate physical symptoms for acute thromboembolic events.

  • Prioritize Hypotheses (Analysis): Focus interventions on optimizing cardiac perfusion and preventing thromboembolic stroke complications.

  • Generate Solutions (Planning): Outline frequency for vital sign monitoring; plan administration schedules for antiarrhythmic and anticoagulant drugs; prepare patient safety education.

  • Take Action (Implementation):

    • Enforce fall precautions.

    • Bleeding Precautions for Anticoagulated Clients: Educate on using electric razors instead of open blades, using soft-bristled toothbrushes, avoiding vigorous dental flossing, avoiding contact sports, and monitoring for occult or overt bleeding.

    • Advise total avoidance of over-the-counter stimulants, alcohol, tobacco, and unprescribed herbal supplements.

    • Administer prescribed negative chronotropes, antiarrhythmics, and systemic anticoagulants.

  • Evaluate Outcomes (Evaluation): Determine if ventricular rate control, sinus conversion, and organ perfusion are achieved.

• Medical and Invasive Therapies:

  • Rhythm/Rate Control Therapies: Direct-Current Electrocardioversion, Catheter Ablation.

  • Pharmacotherapy: Chronic oral anticoagulants, antiarrhythmic agents.

  • Lifestyle: Dietary alterations to reduce cardiovascular stress.

Atrial Flutter (A-Flutter): Conduction Dynamics and Nursing Care

• Pathophysiology and Conduction Mechanics:

  • A supraventricular dysrhythmia characterized by a rapid, highly regular atrial rate.

  • Triggered by a macro-reentrant circuit firing multiple rapid electrical impulses in the atria faster than the AV node can conduct.

  • Atrial Rate: Ranges between $240\text{ to }400\,bpm$.

  • Ventricular Rate: Typically controlled between $60\text{ to }100\,bpm$ due to AV nodal refractoriness blocking a portion of impulses.

  • Rhythm: Regular overall rhythm.

  • ECG Features: Absence of normal P waves; replaced by classic uniform "sawtooth" or "flutter" waves (F-waves) preceding QRS complexes.

• Clinical Presentation:

  • Lightheadedness, palpitations, hypotension, dizziness, chest discomfort, and dyspnea.

• Nursing Process Implementation:

  • Identical clinical management, bleeding precautions, safety considerations, and pharmacological strategies as Atrial Fibrillation.

  • Recognize Cues: Obtain history for causative risk factors, log medications, monitor vital signs and $SpO_2$, interpret telemetry.

  • Take Action: Monitor vital signs, administer antiarrhythmics and anticoagulants, and prepare the client for synchronized electrocardioversion if hemodynamically compromised.

Supraventricular Tachycardia (SVT): Pathophysiology, Clinical Features, and Emergency Interventions

• Pathophysiology and Classification:

  • A category of dysrhythmias classified as narrow-complex tachycardias originating above the ventricles, specifically involving the AV node.

  • Creates hyper-excitability of atrial tissue resulting in rapid heart rates.

  • Paroxysmal SVT (AV Nodal Reentrant Tachycardia / AVNRT): Characterized by sudden, abrupt onset and spontaneous termination without identifiable external precipitating factors.

• ECG Diagnostic Criteria:

  • Heart Rate: Elevated, ranging between $100\text{ to }220\,bpm$

  • Rhythm: Strictly regular

  • QRS Complex: Narrow morphology, measuring less than $0.12\,s$ ($< 0.12\,s$)

  • P Waves: Undiscernible (buried within preceding QRS complexes or T waves)

• Clinical Presentation and Diagnostics:

  • Manifestations occur abruptly: severe dizziness, lightheadedness, syncopal episodes, significant hypotension, dyspnea, and sudden palpitations.

  • High risk for patient falls secondary to sudden drop in cerebral perfusion.

  • Diagnostic Testing: No specific blood tests diagnose SVT; serum panels (blood glucose, thyroid function, renal function tests) are drawn to detect secondary metabolic precipitants such as hyperthyroidism, diabetes, or renal failure.

• Nursing Process Implementation:

  • Recognize Cues (Assessment): Evaluate acute complaints, check vital signs immediately, and obtain rapid 12-lead ECG.

  • Analyze Cues (Analysis): Identify narrow-complex tachycardic features and assess current hemodynamic stability.

  • Prioritize Hypotheses (Analysis): Focus on restoring hemodynamic stability and converting the rhythm to Normal Sinus Rhythm.

  • Generate Solutions (Planning): Plan emergency measures to prevent cardiac ischemia, dyspnea, and profound hypotension.

  • Take Action (Implementation):

    • Continuously monitor blood pressure and pulse rate.

    • Instruct and assist the client with non-invasive vagal maneuvers (e.g., modified Valsalva maneuver).

    • Pharmacological Management: Administer IV Adenosine as a rapid, direct IV push at a dose of $6\,mg$ delivered over $1\text{ to }3\text{ seconds}$, immediately followed by a rapid $20\,mL$ $\text{0.9\% Normal Saline (NS)}$ flush.

    • If rhythm conversion fails to occur within $1\text{ to }2\text{ minutes}$, administer a second dose of IV Adenosine at $12\,mg$ rapidly, followed immediately by a $20\,mL$ NS flush.

    • Emergency Precaution: Adenosine causes transient heart block/asystole; emergency resuscitation equipment and a defibrillator must be present at the bedside prior to administration.

    • Alternative Intravenous Medications: IV Diltiazem, IV Esmolol, or IV Metoprolol.

  • Evaluate Outcomes (Evaluation): Re-assess cardiac rhythm for successful conversion to sinus rhythm and monitor for stabilization of blood pressure.

Epidemiological, Etiological, and Disease Risk Factors in Cardiovascular Care

• Nonmodifiable Risk Factors:

  • Advanced Age

  • Biological Sex

  • Family History of premature cardiovascular disease

  • Race and Ethnicity

• Modifiable Risk Factors:

  • Physical Inactivity / Sedentary Lifestyle

  • Poor Sleep Hygiene or Chronic Sleep Deprivation

  • Tobacco Use (smoking or chewing)

  • Obesity

  • Atherogenic Lipid Profiles (Hyperlipidemia)

  • Hypertension (HTN)

  • Diabetes Mellitus (DM)

  • Unmanaged Psychological Stress

  • Elevated Plasma Homocysteine Levels

• Chronic Comorbidities and Disease States:

  • Hyperlipidemia

  • Thyroid Diseases (Hypothyroidism / Hyperthyroidism)

  • Clinical Depression

  • Joint Pain / Osteoarthritis

  • Elevated Body Mass Index (BMI of $30$ or greater)

  • Gout

  • Malignancy (Cancer)