Percutaneous Transluminal Coronary Arteriography

Anatomy and Physiology

Anatomy

The left main coronary artery arises from the left coronary sinus of the aorta and divides into a left anterior descending artery (LAD)and left circumflex artery (LCx). The left anterior descending artery gives off-diagonal branches, which supply arterial blood to the anterolateral myocardium, and anterior septal branches, which supply blood to the anterior interventricular septum and anterolateral papillary muscles. The terminal part of the LAD provides the left ventricular apex. The left circumflex artery divides into obtuse marginal branches. It supplies blood to the posterolateral side of the left ventricle (see Image. Left Coronary Angiogram, Various Orthogonal Views). [5]

The right coronary artery originates from the right coronary sinus of the aorta. It travels along the right atrioventricular groove and divides into the posterolateral branch and posterior descending artery. It also gives off the sinoatrial nodal artery and right ventricular marginal artery. The dominance of coronary circulation depends on the posterior descending artery. The right dominant circulation is widespread because, 80-85%of the time, PDA comes from the right coronary artery (see Image. Right Coronary Angiogram, Two Orthogonal Views).[5]

Anomalous coronary arteries are relatively rare ( 1-2%). Among them, Anomalous circumflex arteries coming off the right coronary sinus or right coronary artery are common. It is considered a benign clinical course. Very rarely, anomalous coronary arteries traverse between the aorta and pulmonary artery, which can be associated with a malignant clinical course.[5] 

Physiology

Epicardial coronary arteries (>400 micrometers) divide into small arteries (<400 micrometers)and eventually arterioles (<100 micrometers) which further divide into capillaries(<10 micrometers). Coronary blood flow is predominant during diastole compared to systole—the epicardial coronary artery transport blood to smaller arteries. Smaller arteries and arterioles control the coronary vascular blood flow by autoregulation. Small arteries, Arterioles, and capillaries determine the index of microcirculatory resistance. Coronary flow reserve (CFR) depends on blood transport, autoregulation, and metabolite exchange at the capillary level (see Graph. Coronary Macro and Microcirculation). Physiological assessment of epicardial coronary stenosis measured by fractional flow reserve (FFR)  and microvascular resistance measured by the index of microcirculatory resistance. Instantaneous wave-free ratio (IFR) can be used in place of fractional flow reserve.[6]

Indications

Coronary angiogram's common indications:

• Stable angina(Canadian cardiology society class II, III, or IV) on maximally tolerated antianginal therapy (preferable > two different classes of antianginals).
• Unstable angina.
• Non-ST-elevation MI.
• High-risk noninvasive testing (more than 3% annual MI or death).
  • Stress ischemia involves more than 10% of the myocardium or more than two coronary territories.   
  • Stress-induced left ventricular(LV) dysfunction (Ejection fraction less than 45% or >10% drop from the baseline).   
  • ST depressions more than 2 mm at low workload or persisting into recovery.
  • Coronary artery calcium scores more than 400 Agaston.
  • Stress-induced LV dilatation.
  • Inducible wall motion abnormalities in more than two coronary artery territories. 
  • Inducible wall motion abnormality at low-dose dobutamine or low heart rate.
  • Left-main more than 50% or multivessel disease with more than 70% stenosis.
  • Exercise-induced ventricular tachycardia, ventricular fibrillation, or ST elevations.
• Successful resuscitation of sudden cardiac death ( if favorable resuscitation features are present).
• Sustained ventricular tachycardia with no clear etiology.
• Chest pain syndrome with unclear etiology and equivocal noninvasive test.
• ST-elevation MI.[7][8]
• Acute coronary syndrome with mechanical complications like mitral regurgitation and ventricular septal defect.Cardiac shock with hemodynamic instability (In selective cases).
• Before surgical intervention when symptomatic valvular heart disease or pericardial disease is suspected.
• Before surgical intervention to ascending aorta with coronary artery involvement. 
• Preoperative and post-surgical evaluation for symptomatic cardiac transplant patients.  
• Suspicion for symptomatic congenital coronary anomalies.

Contraindications

Absolute Contraindication

•  Extremely limited life expectancy with no clinical benefit from coronary revascularization.   

Relative Contraindications (Applicable for non-emergent coronary angiograms)

•  Acute on chronic kidney injury; end-stage renal disease.
•  Active bleeding; severe anemia with unknown etiology.
•  Severe hemorrhagic disorder. Platelets less than 50,000. 
•  Recent direct oral anticoagulants (DOACs) or Coumadin use.
•  Recent thrombotic or hemorrhagic stroke. [8][9]
•  Severe sepsis and septic shock; Untreated bacteremia.
•  Altered mental status/ Unable to follow commands.
•  Acute pulmonary edema.
•  A patient who refused pre-treatment for contrast allergy.
•  Status post cardiac arrest with unfavorable resuscitation features present ( PH <7.2, elevated lactate  >7,  age more than 85, ESRD,> 30 min to ROSC, no bystander CPR, unwitnessed cardiac arrest).

Equipment

• Micro (25G) or macro (18G) puncture needles can be used for arterial access. 

• Vascular ultrasound for common femoral and radial artery vascular access is highly recommended.

• Low osmolar contrast agents (Iohexol and Iopamidol) and Iso-osmolar contrast agents (Iodixanol) are associated with lower contrast-induced nephropathy.

• Standard miscellaneous inventory for both femoral and radial approach: Band bag, 36 x 40 in., with tape; Bowl, guidewire, 2500cc; Bowl, sponge, 32oz., 1000cc; Clamps, towel, 41/2 in., plastic, blue, curved; Cover, setup, 54 x 90. drape, femoral angiography, 80 x 135 in. Forceps, Halstead mosquito, five in., curved.   Gowns, X-Large. Labels, a sheet of 22 waterproofs. Marker, skin, dual-tip Medicine cup, two oz., 60 ccs, graduated. Needle holder, nest, foam block. Needle, 18G x 11/2 in. Needle, 25G x 11/2 in. Scalpel, #11, safety. Sponges, 4 x 4 in., 4-ply. Syringe, control, luer lock, 10mL.Syringes, luer lock, 10mL.Syringes, luer lock, 20mL. Table cover, 50 x 90 in. Towels, absorbent, white. Towels, OR, blue. Manifold. Pressure bag. Pressure transducer.

• Fluoroscopy is common for femoral and radial approaches (see Image. Cardiac Catheterization Lab). 

Personnel

The cardiac catheterization laboratory team should include:

• Cath lab medical director 
• Cath lab nurse manager 
• Interventional /Invasive cardiologist 
• Cath lab nurse 
• Cath lab technician 
• Janitor 
• Chaplain 
• Pharmacist 
• Echo technician 
• Transporter

Preparation

Step 1

The Cath lab charge nurse or scheduler will contact the patient regarding preoperative instructions.

• Nothing by mouth for 6-8 hours.
• Not to take anticoagulants.
• Discuss patient transportation options before and after the procedure.
• Review of home medications with a patient.
• Review of patient allergies.
• Review of the patient's labs, chest x-ray, urinalysis, and other preoperative testing.
• Review of the indication for a coronary angiogram with the patient.
• Expected time of the procedure.
• Expected time to check in at the Cath lab.

Step 2

• The Cath lab nurse will accompany the patient from the check-in counter to the Cath lab.
• Safely lock the patient's items.   The patient wears a surgical gown.
• The nurse records the patient's vital signs (heart rate, blood pressure, temperature, and respiratory rate).
• Insertion of IV access, preferably one on both arms.
• Connect the patient to telemetry and blood pressure monitor.
• Obtain Baseline EKG.
• Review of all the blood work and preoperative testing with the patient.
• Brief physical examination.
• IV hydration will be started based on the patient's clinical condition ( Normal saline is preferable to N acetylcysteine and bicarbonate solution).

Step 3

• Interventional/Invasive cardiologist explains the procedure limitations and benefits in detail to the patient and obtains written consent.

Step 4

• Brief physical examination by the physician.  Modified Barbeau test for radial access.  Routine groin check for femoral access.   The physician finalizes the access route and the preferred catheters.

Step 5

• Cath lab technician connects pressure transducers and flushes all the diagnostic catheters.  They will prepare the inventory based on the physician's preference.

Step 6

• The patient will be supine on the Cath lab table and covered under a sterile drape.  The patient's groin or wrist will be prepped and sterilized for the procedure.  The Cath lab technician organizes the inventory table and also helps with rotating C-arm.

Step 7

• The Cath lab nurse will organize medications like lidocaine and moderate sedation and help prep vascular ultrasound.

Step 8

• Cath lab technician or nurse will do a Pre-procedure time-out.

Step 9

• The second technician or nurse will be ready to enter all the hemodynamic data in the Cath lab reading room.

Technique or Treatment

The patient will receive moderate sedation and local anesthesia before arterial access.

Arterial Access

• Common femoral artery access:
  • Under fluoroscopic and ultrasound guidance, obtain common femoral artery access with an 18 G large or 25 guide arch needle.
  • Once blood flow pulsatility conformed, advance 0.35 in J-wire or 0.14 in microwire through the needle into the common femoral artery and iliac arteries under fluoroscopy guidance. Remove the needle
  • Introduce 5 French or 6 French access sheaths over the wire into the common femoral artery in a retrograde fashion. Connect the access sheath side port to the IV pressure flush line.
  • Inject 50: 50 through the side port into the sheet and perform a femoral artery angiogram.
  • Flush the sheath frequently
• Radial or Ulnar artery access:
  • Under ultrasound guidance, obtain radial /ulnar artery access with  25 gueuze microneedle.
  • Once blood flow Pulsatility conformed, advance  0.14 in microwire through the needle into the radial/ulnar artery and remove the needle.
  • Introducing 5 French or 6 French access sheath over the wire into the radial/ulnar artery in a retrograde fashion. Connect the access sheath side port to the IV pressure flush line.
  • Inject radial cocktail ( nitroglycerin, nicardipine, or verapamil) and IV heparin through the side port.
  • Flush the sheath frequently.

Left main coronary artery cannulation:

• Advance diagnostic catheters ( JL, AL, Jacky, or Tiger) over the wire under fluoroscopy guidance. Once a catheter tip is in the left coronary sinus, remove  0.35 in support wire. Obtain aortic pressure and waveform for baseline measurements. Engage the left main coronary artery with a slow, steady clock, counter clock, and push and pull maneuver. Left anterior oblique view preferred to engage the left main coronary artery. Obtain angiogram pictures by injecting IV contrast into the left main with steady pressure. It is crucial to review pressure tracing an EKG before the injection. Avoid injecting contrast if pressure is dampened.   Obtain angiogram pictures in the right anterior oblique caudal, right anterior oblique cranial, left anterior oblique cranial, and left anterior oblique caudal. Exchange the catheter over the wire under fluoroscopic guidance. (Media Item 2)

Right coronary artery cannulation:

•  Advance diagnostic catheters (JR, AR, Jacky, or Tiger) over the wire under fluoroscopy guidance. Once a catheter tip is in the right coronary sinus, remove  0.35 in support wire. Obtain aortic pressure and waveform for baseline measurements. Engage the right coronary artery with slow and steady clock, counter clock, and push and pull movements. Left anterior oblique view preferred to engage the right coronary artery. Obtain angiogram pictures by injecting IV contrast into the right coronary artery with steady pressure. It is vital to review pressure tracing and EKG before the injection. Avoid injecting contrast if the pressure is dampened. Obtain angiogram pictures in the right anterior oblique,  left anterior oblique, and left anterior oblique cranial views. Exchange the catheter over the wire under fluoroscopic guidance. (Media Item 3)

Saphenous venous bypass graft (SVG) cannulation:

•  Advance diagnostic catheters over the wire under fluoroscopy guidance.    Preferably JR, AR, and AL  catheters are for SVG to left-sided grafts and multipurpose catheters for SVG to RCA grafts. Once a catheter tip is in the SVG ostium or near the radiopaque marker, remove  0.35 in support wire. Obtain aortic pressure and waveform for baseline measurements. Engage SVG with slow and steady clock, counter clock, and push and pull movements.    The right anterior oblique view is preferred to engage left-sided SVG grafts, and the Left anterior oblique is preferred to engage right-sided grafts. Obtain angiogram pictures by injecting IV contrast into the SVG  with steady pressure. It is crucial to review pressure tracing an EKG before the injection. Avoid injecting contrast if the pressure is dampened.   Obtain angiogram pictures in the right anterior oblique,  left anterior oblique, and left anterior oblique cranial or caudal views. Exchange the catheter over the wire under fluoroscopic guidance.

Internal mammary artery (IMA) cannulation:

• Advance diagnostic catheters ( AR or IMA catheters) over the wire under fluoroscopy guidance. Once a catheter tip is in the IMA  ostium, remove 0.35 in support wire. Obtain aortic pressure and waveform for baseline measurements. Engage IMA with slow and steady clock, counter clock, and push and pull movements.     Anteroposterior or Right anterior oblique view is preferred to engage LIMA and Left anterior oblique is preferred to engage RIMA. Obtain angiogram pictures by injecting IV contrast into the IMA  with steady pressure. It is essential to review pressure tracing an EKG before the injection. Avoid injecting contrast if the pressure is dampened.   Obtain angiogram pictures in right anterior oblique cranial and left anterior oblique cranial views. Exchange the catheter over the wire under fluoroscopic guidance.   Left radial access is preferred if the left internal mammary artery is present. Before engaging the internal mammary artery, one should engage the subclavian artery in the femoral access approach.

Post-angiogram steps:

•  Review angiogram pictures once it is completed.
•  Remove catheters over the wire under fluoroscopic guidance.   
•  Consider a closure device if the access site is optimal at the common femoral artery.
•  Apply TR band for radial or ulnar access site.
•  Transfer the patient to the postprocedure recovery area.
•  Watch for blood pressure, oxygen saturation, and rhythm changes carefully.
•  Once the patient recovers from sedation and vital signs are within normal limits, consider discharging the patient if inpatient care is unnecessary.
•  Discussed the angiogram results with the patient and family in detail.
•  Arrange outpatient follow-up.
•  Review the medications before discharge.

Complications

Early Complications

• Access site hematoma.
• Acute Kidney Injury.
• Stroke ( Embolic or Hemorrhagic).
• Thromboembolic events.
• Acute blood anemia requiring blood transfusion.
• Access site pain.
• Myocardial infarction (Abrupt closure of coronary artery).
• Acute pulmonary edema.
• Emergency Coronary artery bypass surgery.
• VT/Vfib.
• Atheroemboli.
• Radiation-related injuries.[8][9]
• A-V fistula.
• Pseudoaneurysm.
• Death

Delayed Complications

• Access site infection.
• Acute Kidney Injury.
• Access site hematoma.
• Radiation-related injuries ( It is common in obese patients, prolonged procedure time, etc.)
• Acute on chronic pulmonary edema. 
• Death

Clinical Significance

A coronary angiogram defines the coronary anatomy and determines the severity of the stenosis of coronary arteries. It would help interventional/invasive cardiologists to plan for appropriate revascularization strategy if indicated. Tools and techniques for coronary angiograms significantly evolved in the last two decades, and complication rates decreased significantly. A coronary angiogram is relatively safe and can be performed in a daycare setting. However, it is not entirely free of complications.

Enhancing Healthcare Team Outcomes

A coronary angiogram is a minimally invasive procedure and can be associated with severe complications. The heart team approach is essential to perform coronary angiograms effectively with minimal complications. The heart team approach consists of an interventional/invasive cardiologist, general cardiologist, cath lab nurse, cath lab technician, cardiothoracic surgeon, primary care physician, or referral physician. Close-loop communication between the heart team members can minimize unwanted complications. Meticulous patient selection is essential for coronary angiograms in stable angina patients. Always review the patient's allergies, home medications, renal function tests, hemoglobin and hematocrit,  platelets, and PT INR before the procedure to avoid common complications.   IV hydration prevents contrast-induced nephropathy. It is vital to watch for pressure tracing and rhythm strips before injecting contrast into the coronary artery ostium. Effective team communication is the key to better cath lab procedure outcomes.[8]

Nursing, Allied Health, and Interprofessional Team Interventions

The cath lab charge nurse or scheduler, or allied health care team member will contact the patient regarding preoperative instructions:

•  Nothing by mouth for 6-8 hours.
•  Not to take anticoagulants.
•  Patient transportation options before and after the procedure.
•  Review the home medications with a patient.
•  Review of patient allergies.
•  Review of the patient's labs, chest x-ray, urinalysis, and other preoperative testing.
•  Review of the indication for a coronary angiogram with the patient.
•  Expected time of the procedure.
•  Expected time to check-in at the cath lab.

On the day of the procedure: 

•  The cath lab nurse or Allied health care member will accompany the patient from the check-in counter to the cath lab.
•  Safely lock the patient's items.   Help the patient wears a surgical gown.
•   Insertion of IV access, preferably one on both arms.
•   Connect the patient to telemetry and blood pressure monitor.
•   Obtain Baseline EKG.
•   Review of all the blood work and preoperative testing with the patient.
•   Brief physical examination.
•   IV hydration based on the patient's clinical condition (Normal saline is preferable to N acetylcysteine and bicarbonate solution).
• Coordinate care and update it to the patient and the patient's family. 
• Administering medications during the procedure. 

Nursing, Allied Health, and Interprofessional Team Monitoring

• Before the procedure, the nurse obtains and monitors the patient's vital signs (heart rate, blood pressure, temperature, and respiratory rate).
• Reporting proceduralist if any pressure wave form dampening, blood pressure changes, or EKG rhythm changes.