5.2 Left Heart Catheterization & Coronary Angiography
Key Takeaways
- Left heart catheterization combines hemodynamic measurement (LV and aortic pressures) with selective coronary angiography to assess anatomy, stenosis, and ventricular function
- Standard diagnostic cath access is radial (preferred) or femoral; the RCIS candidate must know sheath sizes, closure devices, and anticoagulation targets
- Coronary angiography uses iodinated contrast injected through selective catheters to opacify vessels; injection rate, volume, and pressure must match vessel size
- Significant coronary stenosis is generally defined as ≥50% diameter reduction for hemodynamic relevance; ≥70% is typically flow-limiting for ischemia assessment
- Left heart cath is indicated for chest pain evaluation, abnormal stress testing, valvular disease workup, cardiomyopathy, and pre-operative assessment
Left heart catheterization (LHC) is the definitive invasive study for coronary artery disease, valvular heart disease, and cardiomyopathy. As an RCIS technologist, you set up the lab, prepare the patient, assist with vascular access, operate hemodynamic recording systems, and support contrast injections while monitoring for complications. Understanding what the physician is measuring—and why—separates a credential-ready specialist from someone who only passes equipment.
Components of a Complete Left Heart Cath
A standard diagnostic left heart catheterization includes:
- Hemodynamic measurements — LV pressure, aortic pressure, and often pulmonary artery and wedge pressures if right heart cath is combined
- Selective coronary angiography — opacification of the LCA and RCA (and grafts if post-CABG)
- Left ventriculography — when wall motion, mitral regurgitation, or LV function assessment is needed
- Aortography — when aortic regurgitation, aneurysm, or dissection is suspected
Many labs perform combined right and left heart cath in a single session for heart failure, valvular disease, or pulmonary hypertension workup.
Vascular Access
| Access Site | Advantages | Considerations |
|---|---|---|
| Radial | Lower bleeding risk, early ambulation, preferred in many labs | Allen test, spasm management, smaller catheters |
| Femoral | Larger sheath options, familiar backup route | Bed rest, retroperitoneal bleed risk, closure device use |
| Brachial | Alternative when radial/femoral unavailable | Higher complication rate; less common |
Sheath sizes commonly range from 5 Fr to 7 Fr for diagnostic work. Interventional cases may require 6–8 Fr systems. Anticoagulation with heparin is standard; ACT targets vary by lab protocol (often 250–300 seconds for diagnostic cath, higher for PCI).
Hemodynamic Measurements
Before coronary injection, the physician obtains pressure tracings:
Left Ventricular Pressure
- Normal peak systolic: ~100–140 mmHg (varies with blood pressure)
- Normal LVEDP: 1–12 mmHg (elevated in diastolic dysfunction, aortic stenosis, mitral regurgitation)
- A wave / V wave patterns on wedge tracings reflect atrial and mitral valve pathology
Aortic Pressure
- Normal systolic: ~100–140 mmHg
- Normal diastolic: ~60–90 mmHg
- Pulse pressure widens in aortic regurgitation and severe anemia; narrows in aortic stenosis and low stroke volume states
Derived Findings from Pressure Tracings
| Finding | Pressure Pattern | Common Cause |
|---|---|---|
| LV-aortic gradient | Peak-to-peak or mean gradient across LV outflow | Aortic stenosis, HOCM |
| Wide pulse pressure | ↑ systolic, ↓ diastolic | Aortic regurgitation |
| Elevated LVEDP | ↑ end-diastolic pressure | Diastolic HF, AS, MR, ischemia |
| Dip-and-plateau (square root sign) | Constrictive pattern on LV/RV | Constrictive pericarditis |
You must recognize artifact (catheter whip, dampening, catheter in wall) and notify the physician when tracings appear unreliable.
Selective Coronary Angiography
Coronary angiography uses iodinated contrast injected through a selectively positioned catheter to opacify the coronary tree. Key technical points:
- Catheter engagement — tip seated at the ostium without deep seating that blocks flow or dissects the vessel
- Injection technique — hand injection or power injector; rate matched to vessel size (typically 3–6 mL/s for LCA, 3–5 mL/s for RCA)
- Contrast volume — minimize total dose (especially in renal insufficiency and heart failure)
- Multiple projections — each stenosis must be viewed in at least two orthogonal views to avoid foreshortening
Stenosis Interpretation
| Stenosis Severity | Typical Significance |
|---|---|
| <50% | Generally not hemodynamically significant |
| 50–69% | Intermediate; may require physiologic testing (FFR/iFR) |
| ≥70% | Typically considered flow-limiting; revascularization candidate when symptoms or ischemia correlate |
| Left main ≥50% | High-risk lesion; often revascularized |
Angiography visualizes luminal diameter only. Intravascular ultrasound (IVUS) and optical coherence tomography (OCT) add plaque burden detail but are beyond basic diagnostic cath scope.
Clinical Indications
Left heart cath and coronary angiography are indicated for:
- Chest pain with high pretest probability or inconclusive noninvasive testing
- Abnormal stress test (ST changes, perfusion defects, stress echocardiography wall-motion abnormalities)
- Acute coronary syndrome — STEMI goes directly to PCI; NSTEMI/unstable angina may go urgently to cath
- Valvular disease — assess coronary disease before valve surgery (especially age >40 or risk factors)
- Cardiomyopathy — exclude ischemic etiology
- Pre-operative assessment — major noncardiac surgery in high-risk patients
- Surveillance — post-transplant vasculopathy, known CAD progression
Relative contraindications include active bleeding, uncontrolled hypertension, contrast allergy without premedication, and refusal. Absolute contraindications are rare in emergent ACS.
Patient Preparation and RCIS Responsibilities
Your pre-procedural checklist includes:
- Verify consent, NPO status, medications (especially metformin and anticoagulants per protocol)
- Confirm creatinine/eGFR for contrast risk
- Prepare hemodynamic transducers—zero at phlebostatic axis, level with LA
- Set up contrast manifold, waste system, and injection syringes
- Confirm radiation protection (lead, shields, dose tracking)
- Perform time-out: patient identity, procedure, access site, allergies
During the case, monitor the patient for chest pain, arrhythmia, hypotension, and contrast reactions. Document hemodynamic values, contrast volume, and fluoroscopy time in the report.
Complications During Left Heart Cath
Recognizing complications early is a scored RCIS competency:
| Complication | Early Sign | Initial Action |
|---|---|---|
| Coronary dissection | Chest pain, ST changes during injection | Stop injection; notify physician; prepare IIb/IIIa or emergent PCI |
| Ventricular arrhythmia | PVCs, NSVT during wire/catheter manipulation | Notify physician; ensure defibrillator pads applied |
| Contrast reaction | Urticaria → bronchospasm → hypotension | Stop contrast; airway assessment; epinephrine per protocol |
| Vascular access bleeding | Hematoma, ↓ BP, tachycardia | Hold anticoagulation; apply pressure; vascular surgery if retroperitoneal |
| Stroke/TIA | Focal neuro deficit post-manipulation | Activate stroke protocol; document air/thrombus embolization risk |
Radial access spasm is managed with verapamil/nitroglycerin intra-arterial cocktail per lab protocol. Femoral closure requires post-procedure bed rest and distal pulse checks per institutional policy.
Which component is NOT routinely part of a standard diagnostic left heart catheterization?
A coronary lesion showing 75% diameter stenosis on angiography is best classified as:
An elevated left ventricular end-diastolic pressure (LVEDP) during left heart cath most commonly suggests which of the following?