Investigating & Intervening:
Cardiac Tools in Action

Cardiac investigations, without the murmur of confusion

Biomarkers: tiny proteins, big decisions:

Biomarker Indications/Interpretation Notes
Troponin T
Troponin I		 A protein found in myocardial cells. Can indicate myocardial injury (ACS, MI). Also elevated in myocarditis, pericarditis, cardiac contusion, defibrillation, PE, CHF, sepsis, renal failure. Rises within 3–6 hours, peaks at 12–24 hours, stays elevated 7–10 days. Troponin I is more specific to cardiac tissue.
Myoglobin Early marker of general muscle injury (MI, trauma, rhabdomyolysis). Rises within 2 hours, peaks at 6–9 hours, normalizes by 24 hours.
Creatinine Kinase (CK) Non-specific marker of muscle injury (MI, trauma, rhabdomyolysis, surgery). Peaks at 12–24 hours, returns to baseline in 2–3 days.
CK-MB More specific than CK, useful in diagnosing reinfarction. Rises within 3–6 hours, peaks at 12–24 hours, back to normal within 47–72 hours.
B-type Natriuretic Peptide (BNP) Marker of heart failure. Released in response to increased strain on the ventricles. NT-ProBNP can be used (longer half-life).

Seeing is believing: cardiac imaging explained:

Imaging Technique Description Indications
Transthoracic Echocardiogram (TTE) Non-invasive ultrasound on chest wall. First-line for structural and functional assessment of cardiac chambers, valves, pericardial effusion, LV function, wall motion abnormalities.
Transesophageal Echocardiogram (TEE) Ultrasound through the esophagus (closer proximity to heart, better resolution). Better visualization of left atrial appendage, prosthetic valves, endocarditis, aortic dissection, interatrial septum defects.
Coronary Angiogram X-ray visualization of coronary arteries through injecting with radiopaque dye via arterial access. Gold standard for coronary artery disease, acute coronary syndromes, pre-CABG evaluation.
Cardiac CT Cross-sectional imaging using X-rays. Assessment of coronary artery calcium (CAC) score, structural heart disease, pre-procedural planning.
CT Coronary Angiogram Non-invasive coronary artery visualization with contrast. Low-to-intermediate risk chest pain, CAD evaluation in stable angina.
Cardiac MRI High spatial resolution. Uses Gadolinium to visualize scarred tissue. Myocarditis, cardiomyopathies, viability assessment, congenital heart disease, pericardial disease.
Myocardial Perfusion Imaging (MIBI) Uptake of radioactive tracer (e.g. Tc-99) allows assessment of myocardial perfusion. Ischemia detection, risk stratification in CAD, viability assessment.

The tools, the wires, the why: cardiac procedures explained:

Procedure Description Indications
Transcatheter Aortic Valve Replacement (TAVR)
aka Transcatheter Aortic Valve Implantation (TAVI)		 Using arterial access (typically femoral) to collapse the existing diseased aortic valve and replace it with a collapsable bioprosthetic valve.
  • Intermediate or high risk for surgical valve replacement
  • Life expectancy >1 year + significant benefit (see PARTNER trial)
Percutaneous Coronary Intervention (PCI) Using arterial access to visualize coronary circulation and open stenotic arteries using balloons or stents.
  • Acute coronary syndromes
  • Symptomatic CAD with suitable anatomy
  • Unstable angina refractory to medical therapy
Coronary Artery Bypass Graft (CABG) Surgical procedure using arterial or venous grafts from the patient to bypass obstructed coronary arteries.
  • ≥50% stenosis of left main coronary artery
  • ≥70% stenosis in three-vessel disease (± LAD involvement)
  • ≥70% two-vessel disease with proximal LAD involvement
  • Sudden cardiac death or life-threatening arrhythmias with ≥70% stenosis
  • Acute MI with failed/not possible PCI and ongoing ischemia or instability
  • Post-MI mechanical complications (e.g. VSR, papillary rupture)
  • Cardiogenic shock in CABG candidates
  • Life-threatening ischemic ventricular arrhythmias with left main or 3VD
Ablation Using heat or cryoenergy to destroy arrhythmogenic foci via transarterial access.
  • Supraventricular arrhythmias (AVNRT, WPW, A-Flutter, focal AT)
  • Afib refractory to Class I or III antiarrhythmics
Implantable Cardioverter Defibrillator (ICD) Device that delivers a shock during life-threatening ventricular arrhythmia.
  • Primary prevention in HFrEF patients on optimal therapy
  • Secondary prevention after VT/VF cardiac arrest
Cardiac Resynchronization Therapy (CRT) Stimulates both ventricles to improve cardiac output; CRT-D includes defibrillator function.
  • HFrEF with EF < 35% and QRS ≥ 130 ms (esp. LBBB) despite optimal therapy