Cardiovascular Pathophysiology and Clinical Management: Shock, HTN, CAD, Angina, Angiography, and Related Therapies

Shock: Pathophysiology, assessment, and treatment

  • Definition: Acute failure of the circulatory system leading to inadequate tissue perfusion and oxygen delivery
  • Types (overview): hypovolemic, cardiogenic, distributive (septic, anaphylactic), obstructive, and mixed etiologies
  • Pathophysiology stages
    • Initial stage: reduced perfusion triggers anaerobic metabolism; lactate accumulation
    • Compensatory stage: autonomic nervous system and RAAS activation cause tachycardia, vasoconstriction, and limited drop in BP
    • Progressive stage: reversal of organ perfusion; multi-organ dysfunction begins
    • Refractory stage: life-threatening failure despite therapy
  • Key assessment components
    • Vital signs (BP, HR, RR, O2 sat)
    • Mental status and level of consciousness
    • Urine output and renal function markers
    • Skin perfusion (cool/clammy skin) and capillary refill
    • Laboratory markers (lactate, base deficit, ABG, electrolytes)
  • General treatment principles
    • Rapid identification and stabilization of underlying cause
    • Fluids for hypovolemic shock if tissue perfusion improves with volume, cautious use if cardiogenic/shock due to pump failure
    • Vasopressors for persistent hypotension after fluid optimization (e.g., norepinephrine)
    • Inotropes for cardiac output support when needed (e.g., dobutamine)
    • Ongoing monitoring in ICU with continuous telemetry and frequent reassessment

Hypertension (HTN): Stages, Diagnosis, S/S, Treatment, patient education

  • Definition: Persistently elevated arterial blood pressure with risk of cardiovascular complications
  • Diagnostic stages (ACC/AHA-style ranges)
    • Normal: BP < 120/80 ext{ mmHg}
    • Elevated: 120/80extmmHg<br/>ightarrow129/79extmmHg120/80 ext{ mmHg} <br /> ightarrow 129/79 ext{ mmHg}
    • Stage 1: 130−139extsystolicextor80−89extdiastolic130-139 ext{ systolic} ext{ or } 80-89 ext{ diastolic}
    • Stage 2: extSystolic≥140extorextdiastolic≥90ext{Systolic} \geq 140 ext{ or } ext{diastolic} \geq 90
    • Hypertensive crisis: >180 ext{ systolic} ext{ and/or } >120 ext{ diastolic}
  • Diagnosis and monitoring
    • Repeated measurements in calm conditions; confirm with ambulatory BP monitoring if needed
    • Screen for end-organ damage (ECG for LVH, labs for kidney function, lipids, glucose)
  • S/S (often asymptomatic in early stages; may include)
    • Headache, dizziness, blurred vision, epistaxis, fatigue
  • Treatment principles
    • Lifestyle modifications: weight reduction, DASH dietary pattern, sodium reduction, physical activity, moderation of alcohol
    • Pharmacologic classes (first-line considerations):
    • Angiotensin-converting enzyme inhibitors (ACE inhibitors) or Angiotensin II receptor blockers (ARBs)
    • Thiazide-like diuretics
    • Calcium channel blockers (dihydropyridines or non-dihydropyridines, depending on patient profile)
    • Individualized targets based on comorbidities (diabetes, CKD, coronary disease)
  • Patient education
    • Importance of medication adherence and regular BP monitoring at home
    • Avoiding NSAIDs and other agents that raise BP
    • Home BP log and recognizing warning signs (fainting, chest pain, shortness of breath)

Coronary Artery Disease (CAD): Pathophysiology, risk factors, assessment

  • Pathophysiology
    • Atherosclerotic plaque buildup in coronary arteries → reduced myocardial blood flow, especially during exertion
    • Imbalance between myocardial oxygen supply and demand can precipitate ischemia or myocardial infarction
  • Major risk factors
    • Modifiable: smoking, hypertension, diabetes, dyslipidemia, obesity, physical inactivity, poor diet
    • Non-modifiable: age, male sex, family history of premature CAD
  • Clinical implications
    • Stable angina, unstable angina, myocardial infarction (STEMI/NON-STEMI), sudden cardiac death risk
  • Assessment focus
    • Chest pain characteristics, radiation, duration, provoking factors, relief with rest or nitroglycerin
    • Associated symptoms: diaphoresis, dyspnea, nausea, syncope
    • Risk factor appraisal and baseline functional status

Angina: S/S, types, and CAD connection

  • Types of angina
    • Stable angina: predictable pattern with exertion or stress; relieved with rest or nitroglycerin
    • Unstable angina: occurring at rest or with increasing frequency/intensity; not reliably relieved by rest or nitro; higher risk of evolving MI
    • Variant (Prinzmetal) angina: vasospastic; occurs at rest; often at same time of day; may be triggered by vasospasm
  • Assessment focus during angina
    • Location, quality, intensity, duration, radiation pattern
    • Associated autonomic symptoms (sweating, pallor, nausea)
    • Response to nitroglycerin and activity changes

Diagnostic tests

  • Electrocardiogram (EKG/ECG)
    • Acute ischemia: ST-segment depression or T-wave inversion; STEMI may show ST-elevation
  • Cardiac enzymes
    • Troponin I/T elevations indicating myocardial injury; serial measurements to track dynamics
  • Lipid panel
    • LDL-C, HDL-C, triglycerides to assess atherogenic risk and guide lipid-lowering therapy
  • Chest imaging and functional testing
    • Echocardiography: wall motion abnormalities, LV ejection fraction (LVEF)
    • Exercise or pharmacologic stress testing: assessment of ischemia/functional reserve
  • Coronary angiography
    • Gold standard for localization and characterization of atherosclerotic lesions; guides revascularization decisions

Angiography: Pre- and post-care, labs, EKG, nursing assessments

  • Pre-procedure care
    • Informed consent and patient education
    • NPO status; assess for allergies (contrast dye, iodine), assess renal function
    • Review anticoagulation/antiplatelet therapy; hold certain meds if needed
    • Baseline vital signs, ECG, and laboratory values (coagulation profile, creatinine)
  • Intra-procedure considerations
    • Monitoring: continuous ECG, BP, oxygen saturation
    • Sterile technique and vascular access management
    • Contrast administration and potential reactions
  • Post-procedure care
    • Pressure dressing and puncture site assessment for bleeding/hematoma
    • Continuous monitoring for chest pain, rhythm disturbances, or contrast-related issues
    • Neurovascular checks and peripheral pulse assessment of the access limb
    • Respiratory status and renal function monitoring due to contrast exposure
    • Activity restrictions and gradual mobilization as ordered
  • Nursing assessments
    • Pain control, bleeding risk, hydration status, electrolyte balance
    • Monitoring for signs of myocardial ischemia or arrhythmias
    • Patient education on post-procedure expectations and activity limits

Medications to treat CAD/Angina

  • Nitrates (e.g., nitroglycerin)

    • Mechanism: venodilation with reduction of preload; higher doses may reduce afterload; improves myocardial oxygen balance
    • Indications: acute angina relief, prophylaxis before exertion
    • Administration/dosing: sublingual tablets or spray; common regimen includes up to 3 doses of 0.3–0.6 mg at 5-minute intervals; seek emergency care if pain persists after first dose
    • Side effects: headache, flushing, dizziness, hypotension; caution with PDE-5 inhibitors

  • Beta blockers (e.g., metoprolol, atenolol)

    • Mechanism: decrease heart rate, contractility, and myocardial oxygen demand
    • Indications: chronic stable angina, post-MI management, hypertension
    • Side effects: bradycardia, fatigue, hypotension, masking of hypoglycemia symptoms

  • Calcium channel blockers (CCBs)

    • Dihydropyridines (e.g., amlodipine, nifedipine): vasodilate coronary and peripheral vessels; may cause edema and reflex tachycardia
    • Non-dihydropyridines (e.g., diltiazem, verapamil): reduce heart rate and contractility; useful in rate control and certain variants of angina
    • Side effects: edema, constipation (especially with verapamil)

  • Antilipidemic agents

    • Statins (e.g., atorvastatin, simvastatin): inhibit HMG-CoA reductase; reduce LDL-C; plaque stabilization and anti-inflammatory effects
    • Monitoring: liver function tests; assess for myopathy
    • Other classes: bile acid sequestrants, fibrates, PCSK9 inhibitors (context-dependent)

Heparin: Action and drip calculation

  • Action
    • Anticoagulant that inhibits thrombin formation and factor Xa activity, reducing clot propagation in ACS and during invasive procedures
  • Drip calculation (infusion rate)
    • Concept: infusion rate in mL/hour is determined from desired units/hour and solution concentration
    • General formula:
      Rate (mL/hr)=Dose (units/hour)Concentration (units/mL)\text{Rate (mL/hr)} = \frac{\text{Dose (units/hour)}}{\text{Concentration (units/mL)}}
    • Monitoring and safety
    • Monitor activated partial thromboplastin time (aPTT) or anti-Xa levels per protocol
    • Adjust infusion to maintain therapeutic range
    • Antidote: protamine sulfate

Patient education

  • Angina and CAD management
    • Recognize triggers and early symptoms; use prescribed nitroglycerin at the onset of symptoms and call emergency services if symptoms persist
    • Adherence to medication regimens, including antiplatelets and statins
    • Lifestyle changes: smoking cessation, diet, exercise, weight management, blood pressure and glucose control
  • Post-diagnostic test expectations
    • What a diagnostic angiography, stress test, or echocardiography entails, including potential sensations and post-procedure care
  • Post-procedure care (laparoscopic or open CABG reference where applicable)
    • Deep breathing, incentive spirometry, gradual activity progression
    • Wound care, signs of infection, and when to seek help

Emergency meds to treat angina: Pre- and post-assessments

  • Pre-assessment considerations
    • Confirm chest pain characteristics, onset, duration, and relief with rest or nitroglycerin
    • Check blood pressure, heart rate, and oxygen saturation; assess mental status
    • Review current medications and contraindications (e.g., PDE-5 inhibitors with nitrates)
    • Verify access to emergency equipment and IV access
  • Acute management medications (typical approach)
    • Nitroglycerin for relief of chest pain; aspirin as early antiplatelet therapy unless contraindicated; consideration of morphine for pain if unrelieved by nitro and if needed
    • Oxygen if hypoxemic (SpO2 < 90% or as clinically indicated)
  • Post-assessment considerations
    • Reassess pain, vitals, and ECG changes after administration
    • Monitor for hypotension or reflex tachycardia; ensure patient safety during rapid changes in hemodynamics
    • Re-evaluate need for additional anti-anginal or anti-ischemic therapy according to protocol

Post-diagnostic tests: Angina, MI, CABG

  • Angina diagnostics follow-up
    • Use ECG and troponin trends to classify ischemia vs infarction progression
    • Reassess risk factors and optimize medical therapy; reinforce lifestyle recommendations
  • Myocardial infarction (MI) considerations
    • Immediate priorities: prompt reperfusion (PCI or thrombolysis), antiplatelet therapy, anticoagulation, and hemodynamic stabilization
    • Post-MI care: monitor for arrhythmias, heart failure symptoms, and LV function; begin/adjust rehab plan
  • Coronary Artery Bypass Grafting (CABG)
    • Indications: multi-vessel disease, failed PCI, or anatomy not amenable to stenting
    • Immediate and long-term post-op considerations: wound care, infection prevention, respiratory therapy, sternal precautions, gradual return to activity, and long-term cardiac rehabilitation

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