Cardiac catheterization

Cardiac catheterization is a procedure used in the diagnosis and treatment of cardiovascular conditions. It involves the insertion of a catheter into a cardiac vessel (coronary catheterization) or chamber by way of a suitable vascular access (usually a femoral or radial artery). Once in position, a cardiac catheter can help evaluate the blood supply to the cardiac musculature (angiography) or open up narrowed or blocked segments of a coronary artery by means of a coronary angioplasty with stenting (percutaneous coronary intervention, or PCI). Additionally, it can be used to perform a cardiac tissue biopsy, open narrowed heart valves via valvuloplasty, examine electrophysiological pathways, or measure pressure and oxygen levels in different chambers (hemodynamic assessment). The procedure is associated with a low rate of complications, with the most common among these being bruising and bleeding at the site of access. Rarer, more severe complications include arrhythmias, cardiac arrest, embolization of existing plaques, and infection.

General

• Arterial catheter insertion sites
  • Most common: femoral artery
  • Radial artery
  • Brachial artery (access generally via cutdown approach)
• Imaging: A contrast dye is injected via the catheter, and is visualized with serial x-ray imaging.
• Preprocedural testing
  • ECG
  • Laboratory tests: complete blood count, INR/prothrombin time, serum urea, and creatinine

Coronary angiography/ventriculography

• Description: Contrast-enhanced radiological analysis of the heart cavities (ventriculography) or coronary arteries (coronary angiography).
• Indications
  • Coronary artery disease: to assess the exact location and extent of coronary vessel narrowing before possible PCI/surgery
    • Patients with unstable angina
    • Patients with adverse effects from medical therapy
    • Patients in which conservative control of symptoms has failed
    • High-risk patients (those with signs of ischemia during stress ECG)
  • Valvular or myocardial diseases with symptoms (e.g., shortness of breath)
  • Recurring chest pain of unidentified cause
  • Preoperative evaluation prior to noncardiac and planned cardiac surgery (CABG) in high-risk patients
  • To detect and quantify the presence of an intracardiac shunt

Coronary angiography is not a screening method for coronary heart disease in asymptomatic patients!

Percutaneous coronary intervention (PCI)/percutaneous transluminal coronary angioplasty (PTCA)

• Description: : A therapeutic procedure carried out during cardiac catheterization; in which a blocked coronary vessel is opened and appropriate blood flow is restored. A balloon catheter is used to dilate the narrowed section, with/without the placement of a stent to keep it patent.
• Indications
  • Acute and chronic occlusion of coronary arteries
    • Myocardial infarction (primary revascularization or primary PCI)
    • Occlusion of bypass grafts and stents
    • Recurrent ischemia after PCI or bypass surgery
• Procedure: a catheter is inserted through the access site → a deflated balloon catheter is advanced into the obstructed artery → balloon is inflated at the obstructed/narrowed section → the narrowing is relieved → stent may/may not be deployed to keep the blood vessel open
• Types of stents
  • Bare metal stent (BMS): bare-surfaced, metallic stent that provides a mechanical framework to keep the artery open.
    • After placement, endothelial cells begin to cover the bare surface of the stent (stent endothelialization) → ↓ exposure time of the foreign, thrombogenic material → ↓ risk of stent thrombosis → ↓ time of post-placement anticoagulation
    • Thus, bare metal stents are better suited to patients who are not compliant with long-term oral medications and/or those who may need to undergo surgery in the near future.
  • Drug-eluting stent (DES): stents that are coated with antiproliferative substances (immunosuppressant drugs, cytostatic drugs) that prevent excessive intimal hyperplasia

Electrophysiological study

• Description: testing of the electrical conduction system of the heart to assess electrical activity and conduction pathways via a cardiac catheter
• Indications
  • Diagnostic: to evaluate various, repeat refractory cardiac arrhythmias
  • Therapeutic
    • Radioablation of areas of accessory pathways (areas that generate and conduct the arrhythmias)
    • Placement of intracardiac pacemakers or defibrillators

Right heart catheterization

• Description: The passing of a balloon-tipped, multi-lumen catheter (Swan-Ganz catheter) into the right side of the heart and the pulmonary artery to monitor pressure within the heart (intracardiac pressure) and pulmonary arterial pressure.
• Indications
  • For patients with heart failure, cardiomyopathy, congenital heart disease, and valvular disease: helps measure pressure, oxygen, and cardiac output of the right heart to assess the severity of dysfunction.
  • It also helps measure pulmonary capillary wedge pressure (PCWP), which can be used to diagnose the severity of left ventricular failure and mitral stenosis.
  • In suspected pulmonary hypertension: helps measure mean pulmonary arterial pressure (mPAP) and central venous pressure (CVP)
• Procedure: venipuncture (groin, arm, neck) → advancement of the Swan-Ganz catheter into the right heart

References:^{[1][1][2][3][4]}

• Absolute contraindication: patient refuses to undergo the procedure
• Relative contraindications: comorbidities in which the risks associated with coronary angiography are greater than the benefits of securing the diagnosis
  • Decompensated heart failure
  • Acute renal failure
  • Uncontrolled, severe hypertension
  • Bleeding disorder or anticoagulated state
  • Allergy to radiographic agents
• Special consideration: Abnormal results on a modified Allen test are a contraindication for radial access.

References:^[2][5]

We list the most important contraindications. The selection is not exhaustive.

Periprocedural complications

Complications at the site of vascular access

• Superficial hematoma formation
• Retroperitoneal hematoma ^[6][7]
  • Epidemiology: Most common cause of unexpected mortality after diagnostic or interventional cardiac catheterization
  • Clinical features
    • Often asymptomatic
    • Suprainguinal tenderness and fullness
    • Sudden flank or back pain with hemodynamic instability
  • Diagnostics: Prompt diagnosis is a priority: CT scan with contrast of the abdomen and pelvis in hemodynamically stable patients or sonography in unstable patients
  • Treatment
    • Predominantly supportive treatment: careful monitoring, fluid resuscitation, blood transfusion, and normalization of coagulation factors if abnormal
    • Surgical repair
      • Endovascular management options like intra-arterial embolization or stent-grafts to stop the bleeding
      • Open surgery to control active bleeding and/or to remove a large retroperitoneal hematoma
• Pseudoaneurysms ^[8]
• Arterial injury; (can include laceration, arteriovenous fistula formation, or thrombosis)

Complications at the cardiac level

• Myocardial infarction
• Arrhythmias can be induced by catheter introduction into the right or left ventricle.
• Spontaneous coronary artery dissection (SCAD) in the artery affected by acute coronary occlusion
• Injury to coronary vasculature by the catheter (e.g., dissection of coronary artery wall)

Other complications

• Hypersensitivity to contrast media
• Acute kidney injury (see also contrast nephropathy)
• Cholesterol embolization syndrome

Delayed complications

• Restenosis (most common complication)
• Stent thrombosis (0.5–5%)
• Vascular complications
  • Spontaneous coronary artery dissection (SCAD; ∼ 5% after PTCA) → increased risk of infarction
  • Systemic embolisms: stroke due to cerebral emboli (< 1%)
• Infection (localized or generalized bacteremia)

We list the most important complications. The selection is not exhaustive.

Coronary artery bypass graft (CABG)/aortocoronary bypass (ACB)

• See also “Procedure” in coronary artery bypass graft.