7 Cardiovascular Clinical Practice Cases

Assess the patient before the rhythm

These cases are for learning and do not replace local protocols, clinical judgment, or emergency care. In a real emergency, activate the response system and follow current institutional procedures.

Start with the patient’s condition rather than the monitor. Assess airway, breathing, circulation, mental status, blood pressure, oxygen saturation, symptoms, and perfusion. Check for a pulse: pulselessness means cardiac-arrest management, not a pulse-based rhythm algorithm.

Describe the rhythm by its rate, regularity, QRS width, and, when visible, the relationship between P waves and QRS complexes. Then decide whether the patient is unstable. Hypotension, shock, acute altered mental status, ischemic chest discomfort, or acute heart failure can signal instability; treat the patient, not just the monitor.

For unstable tachyarrhythmia with a pulse, synchronized cardioversion is generally the priority. Defibrillation is used for pulseless ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT).

Stable regular tachycardia

A patient with sudden palpitations, a regular rhythm at $\frac{190\ \text{beats}}{\text{min}}$, narrow QRS complexes, blood pressure of $122\ \text{mm Hg systolic}$ and $76\ \text{mm Hg diastolic}$, alertness, and no chest pain or signs of heart failure has stable regular narrow-complex tachycardia. A re-entrant supraventricular tachycardia is possible.

Continue monitoring, obtain IV access and a 12-lead ECG if available, and try a vagal maneuver. If the rhythm persists, adenosine may be used under the applicable protocol. Reassess the rhythm and symptoms after each intervention.

Adenosine is intended for regular rhythms and is not a general treatment for irregular tachycardia. It may sometimes be considered for regular, monomorphic wide-complex tachycardia under an expert protocol. Confirm regularity, monitor continuously, and be ready for brief rhythm changes.

Unstable atrial fibrillation

A rhythm that is irregularly irregular at $\frac{170\ \text{beats}}{\text{min}}$, together with blood pressure of $78\ \text{mm Hg systolic}$ and $46\ \text{mm Hg diastolic}$, confusion, and cool, clammy skin, indicates atrial fibrillation with rapid ventricular response and hemodynamic instability.

Call for emergency support and prepare for immediate synchronized cardioversion. Do not delay lifesaving cardioversion to try routine rate-control medication. Provide airway and breathing support and attach monitoring. Consider sedation when feasible without delaying treatment.

Anticoagulation and longer-term rhythm or rate management require subsequent clinician assessment. A sudden-onset, regular narrow rhythm differs from atrial fibrillation, which is characteristically irregularly irregular.

Bradycardia with compromise

Dizziness and confusion with a heart rate of $\frac{34\ \text{beats}}{\text{min}}$ and blood pressure of $82\ \text{mm Hg systolic}$ and $50\ \text{mm Hg diastolic}$ indicate bradycardia with cardiopulmonary compromise. Possible causes to consider include ischemia, hypoxia, medication effects, and electrolyte disturbance.

Support airway and breathing, monitor the patient, obtain IV access, and treat reversible causes. Under the 2025 AHA adult algorithm, atropine is used for persistent bradycardia with compromise. If it is ineffective, proceed to transcutaneous pacing and/or dopamine or epinephrine infusion, and consider expert consultation or transvenous pacing.

Do not let an ECG or medication review delay needed stabilization. For symptomatic bradycardia, if atropine is ineffective, do not delay pacing or infusion support when indicated.

Suspected acute coronary syndrome

Central chest pressure, sweating, nausea, and shortness of breath, together with ST-segment elevation in contiguous leads on a 12-lead ECG, indicate suspected ST-elevation myocardial infarction, a time-critical acute coronary syndrome.

Activate emergency ACS and reperfusion pathways immediately. Obtain and interpret an ECG promptly, maintain continuous monitoring, and arrange urgent coronary reperfusion according to the local STEMI system. Give aspirin when indicated and not contraindicated, following protocol. ACS antiplatelet plans commonly include aspirin plus a P2Y12 inhibitor, but bleeding risk and the treatment strategy matter.

Oxygen is not routine treatment for every patient: assess oxygenation and provide oxygen when indicated. Before nitroglycerin, assess blood pressure and contraindications, including possible right-ventricular infarction or recent phosphodiesterase-5 inhibitor use. Nitroglycerin symptom relief does not rule out myocardial infarction and must not delay reperfusion.

Acute decompensated heart failure

Worsening breathlessness, difficulty lying flat, crackles, leg edema, and low oxygen saturation in a person with known heart failure indicate acute decompensated heart failure with pulmonary congestion. Assess for hypoxia, poor perfusion, ischemia, and arrhythmia.

Sit the patient upright, assess airway and breathing, monitor oxygenation and rhythm, and obtain urgent clinical assistance. Give oxygen for hypoxemia and consider noninvasive ventilation when clinically appropriate and available. Clinicians may use IV loop diuretics for congestion; vasodilators may be considered in selected patients with adequate blood pressure. Avoid reflexively giving a fluid bolus when pulmonary congestion is present.

Once the patient is stabilized, guideline-directed therapy for heart failure with reduced ejection fraction (HFrEF) includes an angiotensin receptor–neprilysin inhibitor, or an ACE inhibitor or ARB when appropriate; an evidence-based beta-blocker; a mineralocorticoid receptor antagonist; and an SGLT2 inhibitor. Treatment is individualized. Beta-blocker initiation or titration is generally not an acute response to shock or severe decompensation.

Pulseless ventricular fibrillation

Sudden collapse with unresponsiveness, no normal breathing, and no pulse, alongside a chaotic, disorganized rhythm without identifiable QRS complexes, indicates cardiac arrest with VF, a shockable rhythm.

Activate the code response, begin high-quality CPR, and defibrillate as soon as possible. Resume CPR immediately after each shock and follow the current cardiac-arrest algorithm. For shockable arrest, 2025 AHA guidance supports prioritizing early defibrillation; epinephrine is reasonable after initial defibrillation attempts have failed.

Continue rhythm checks and address reversible causes. Do not delay compressions or shock delivery for IV/IO access or medication preparation.

Medication choices and cautions

Medication choice depends on rhythm, hemodynamics, contraindications, and protocol. Assessment and monitoring remain essential alongside the medication decision.

• Adenosine: For selected regular narrow-complex tachycardia; sometimes considered for regular, monomorphic wide-complex tachycardia under expert protocol. Confirm rhythm regularity, monitor continuously, and be ready for brief rhythm changes.

• Atropine: For symptomatic bradycardia with compromise. If ineffective, do not delay pacing or infusion support when indicated.

• Beta-blockers: Used in chronic HFrEF therapy and selected rate-control situations. Check heart rate, blood pressure, conduction, and signs of acute decompensation; do not assume they are appropriate during shock.

• ACE inhibitors, ARBs, or ARNI: HFrEF disease-modifying therapy. Monitor blood pressure, kidney function, and potassium; avoid combining an ACE inhibitor with an ARNI.

• Mineralocorticoid receptor antagonists: HFrEF disease-modifying therapy; monitor potassium and kidney function.

• SGLT2 inhibitors: HFrEF therapy, including for patients without diabetes. Review renal status, volume status, and patient-specific contraindications.

• Aspirin plus a P2Y12 inhibitor: A common antiplatelet strategy after ACS. Weigh bleeding risk; duration and choice are individualized.

• Nitroglycerin: May relieve symptoms in selected ischemic or congestive presentations. Check blood pressure and contraindications; it does not replace ACS evaluation or reperfusion.

• Loop diuretics: May relieve fluid congestion in heart failure. Assess volume status, blood pressure, renal function, and response.