4.2 Cardiovascular Disorders & Management

Heart Failure

Heart failure (HF) is the heart's inability to pump enough blood to meet metabolic demands. Classify it by ejection fraction:

• HFrEF (reduced EF, 40% or less) — systolic failure; the ventricle cannot contract effectively
• HFpEF (preserved EF, 50% or more) — diastolic failure; the ventricle is stiff and cannot fill
• HFmrEF — mildly reduced EF, 41-49%

NYHA Functional Classification

Monitoring and Self-Care Teaching

• Daily weight: same time, same scale, similar clothing, after voiding. Report a gain of 2-3 lb in 24 hours or 5 lb in a week
• Fluid restriction of 1.5-2 L/day is typical for advanced or hyponatremic HF; restrict sodium to about 2 g/day
• Left-sided failure produces pulmonary symptoms: dyspnea, orthopnea, crackles, S3, and pink frothy sputum. Right-sided failure produces systemic congestion: JVD, peripheral edema, hepatomegaly, and ascites

Key Drug Classes

• ACE inhibitors (lisinopril) and ARBs (losartan): reduce afterload and ventricular remodeling; monitor potassium and creatinine. A dry cough is common with ACE inhibitors; angioedema is a stop-the-drug emergency
• ARNI (sacubitril/valsartan): requires a 36-hour washout after the last ACE-inhibitor dose to prevent angioedema
• Beta blockers (metoprolol succinate, carvedilol): start low and titrate up; hold for bradycardia or hypotension; never stop abruptly (rebound tachycardia and ischemia)
• Loop diuretics (furosemide): monitor potassium; rapid IV push can cause ototoxicity
• Spironolactone: potassium-sparing aldosterone antagonist; watch for hyperkalemia and gynecomastia
• SGLT2 inhibitors (dapagliflozin, empagliflozin): reduce HF hospitalizations even in patients without diabetes
• Digoxin: therapeutic level 0.5-2.0 ng/mL. Toxicity (above 2.0) causes anorexia, nausea, vomiting, bradycardia, and yellow-green visual halos; hypokalemia potentiates toxicity even at normal levels. Take an apical pulse for a full minute and hold the dose if below 60 beats/min. The antidote for severe toxicity is digoxin immune Fab

Acute Coronary Syndrome

ACS spans unstable angina (no troponin rise), NSTEMI (elevated troponin without persistent ST elevation), and STEMI (ST elevation of 1 mm or more in two contiguous leads from total coronary occlusion). Reperfusion timelines: door-to-balloon (PCI) within 90 minutes; door-to-fibrinolytic (needle) within 30 minutes. Time is muscle.

The classic MONA mnemonic has been updated: morphine is reserved for refractory pain (not routine); oxygen only if SpO2 is below 90%; nitroglycerin 0.4 mg sublingual every 5 minutes for up to 3 doses — hold if systolic BP is under 90 mm Hg, if a phosphodiesterase inhibitor (sildenafil, tadalafil) was used in the last 24-48 hours, or if right ventricular infarction is suspected; aspirin 162-325 mg chewed (non-enteric) remains first-line.

Dysrhythmias

• Atrial fibrillation: irregularly irregular rhythm with no P waves. Goals are rate control (metoprolol, diltiazem) and stroke prevention with anticoagulation guided by the CHA2DS2-VASc score. If duration exceeds 48 hours or is unknown, provide therapeutic anticoagulation for about 3 weeks (or confirm no thrombus with TEE) before cardioversion, and continue anticoagulation at least 4 weeks after
• First-degree AV block: constant PR interval above 0.20 s; usually monitor only
• Second-degree Mobitz I (Wenckebach): PR progressively lengthens until a beat is dropped; atropine if symptomatic
• Second-degree Mobitz II: dropped QRS complexes without PR lengthening; high risk of progressing to complete block — prepare for a pacemaker
• Third-degree (complete) heart block: AV dissociation; atropine is often ineffective — use transcutaneous then transvenous pacing
• Ventricular fibrillation and pulseless ventricular tachycardia: shockable rhythms — immediate CPR, unsynchronized defibrillation, and epinephrine 1 mg IV every 3-5 minutes
• Asystole and PEA: NOT shockable — CPR and epinephrine while searching for reversible causes (the Hs and Ts)
• Tachycardia with a pulse: vagal maneuvers and adenosine for stable SVT; synchronized cardioversion for unstable patients who still have a pulse. Never cardiovert a pulseless patient — defibrillate instead

Hypertension

ACC/AHA thresholds: normal is below 120/80 mm Hg; elevated is 120-129 with diastolic under 80; Stage 1 is 130-139 or 80-89; Stage 2 is 140 or higher, or 90 or higher. Confirm readings with proper technique: seated with back supported, feet flat, correct cuff size, arm at heart level, and no caffeine or smoking within 30 minutes.

• Hypertensive urgency: severe elevation (often 180/120 mm Hg or higher) without acute target-organ damage; treat with oral agents and lower pressure gradually over 24-48 hours
• Hypertensive emergency: severe elevation with acute target-organ damage (encephalopathy, aortic dissection, pulmonary edema, eclampsia, acute MI); admit to the ICU and use IV agents (nicardipine, labetalol, nitroprusside). Reduce mean arterial pressure by no more than 20-25% in the first hour — faster drops risk ischemic stroke and coronary hypoperfusion

Peripheral Arterial vs Venous Disease

Teach patients with PAD to follow structured walking programs, stop smoking, practice meticulous foot care, and avoid crossing the legs or wearing constrictive clothing.

Clinical Pearls

• Store nitroglycerin in its dark glass bottle, expect a tingling or burning sensation under the tongue, and replace the supply about every 6 months
• Teach patients on digoxin to report visual changes, nausea, or a slow pulse before taking the next dose
• Never massage a swollen, tender calf — if the cause is a deep vein thrombosis, massage can dislodge the clot and cause a pulmonary embolism