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What is a heart cath?

September 29, 2012

Heart catheterization has become a relatively common diagnostic procedure.  I’d like to explain in detail what a heart cath is, why it is done, and what the experience is like.

In brief, this is a procedure in which a catheter is inserted into an artery or vein (depending on which part of the heart you want to look at) and threaded up to the heart with the aid of fluoroscopy (live action xray).  A special dye called contrast, that shows up on xray, is injected through the catheter so structures can be seen under fluoroscopy. There are some procedures such as angioplasty and stenting of narrowed arteries that can be done during the cath.

Heart catheterization is done as both a diagnostic procedure (to get information) and as an interventional procedure (to fix structural abnormalities).  This procedure is performed by a cardiologist who has had additional training in invasive procedures.  This type of cardiologist is called an interventional cardiologist.  A more specialized interventional cardiologist is the electrophysiologist (EP).  The EP specialist is an expert in heart rhythm and conduction problems and performs procedures such as EP studies (heart cath where the electrical conduction of the heart is studied in detail), ablations (destruction of heart conductive tissue that is causing rhythm problems), and pacemaker or internal cardiac defibrillator (ICD) insertion.  There are also invasive diagnostic cardiologists, cardiologists who perform diagnostic caths but do not do procedures such as angioplasty.

There are several reasons why a heart cath may be done.  Some are done emergently, when someone is having a heart attack.  In this case, the hope is that there is a coronary artery that is blocked that can be opened through angioplasty and stenting.  In some cases, the blockage is not in a suitable place for stenting and open heart surgery by a cardio-thoracic surgeon is required.  Sometimes the blockage is in too small a vessel for stenting or bypass and the patient is treated with medications.  My first heart cath was emergent, when I had my heart attack.

Heart caths are done diagnostically if a narrowed coronary artery is suspected.  In this case a patient may have been having symptoms suspicious of angina or had an abnormal test such as an EKG or stress test. A diagnostic cath may also be done when someone is preparing to have another surgery or procedure and it is vitally important to know the condition of the heart.  During a diagnostic cath, if a critically narrowed artery is found, it may be stented immediately if this is deemed appropriate for the patient.

It is possible to gather information about different parts of the heart depending on the approach used.  A left heart cath (the most common) requires the catheter to be advanced through an artery, arriving at the heart through the aorta.

Arterial access for left heart catheterization.

From the aorta, the catheter may be advanced into the left ventricle through the aortic valve in order to measure the pressures in the ventricle and measure its size.  Ejection fraction, the amount of blood ejected from the ventricle each time the heart pumps, is measured also.

The coronary arteries are accessed from the aorta where they take off, close to the aortic valve, just outside the heart.  Here the catheter can be advanced through the right and left coronary arteries and the various branchings can be seen by injecting contrast and viewing the flow via fluoroscope.

A right heart cath is performed to make similar measurements of the right ventricle and to measure pressure in the pulmonary artery.  Access is gained through the femoral vein in the groin, or the internal jugular vein in the neck.  The catheter is advanced to the vena cava and then into the right atrium.  Pressures are measured in right side of the heart as the catheter is moved through the right atrium and right ventricle, then into the pulmonary artery as it exits the heart.  Right heart catheterization may be performed to evaluate

Coronary arteries.

congestive heart failure or pulmonary hypertension or conditions such as shock in a critically ill patient.

The patient’s experience may differ depending on the circumstances of the procedure.  Emergent caths may happen minutes after one arrives in the emergency room, in my case 23 minutes (or so I’m told).  In a non-emergency situation, the procedure may be planned weeks in advance and performed outpatient with the patient going home the same day.  The

Right heart catheterization.

patient’s experience in the cath lab will be similar in either case.

The inside of the cath lab looks a lot like an operating room, though usually smaller and with dimmer lights.  The fluoroscopy equipment takes up most of the room and there are tv screens next to where the patient bed is.  The room will probably be cold, but you’ll be given warm blankets.  An IV is needed for the procedure and this is usually inserted before going into the lab.  The area where arterial or venous access will be gained will be shaved and cleaned.  You will be moved onto a flat bed and positioned under the fluoroscopy equipment.  Monitor leads will be applied and you’ll receive oxygen.  Sterile drapes are put over your entire body except where the cardiologist will puncture the skin.  You’ll be given medication through the IV for pain and to help you relax.  The doctor injects local anesthetic to numb the skin before accessing the artery or vein.  That injection stings, but after that there usually is no more pain.  If you want to, you can watch on the tv screen as the catheter is advanced to the heart.  In my first cath, I felt an increase in chest pain while the balloon was inflated inside my blocked artery.  That lasted less than a minute and I felt no more pain during the rest of the procedure.  After the cath is completed, the sheath that was placed in the artery or vein may be removed or it may need to be left in place for a few hours.  When the sheath is removed it is necessary to apply pressure until the area stops bleeding.  Sometimes a closure device is used, such as Angioseal.  This is a small collagen plug that is inserted through the sheath to block the hole left in the vessel as the sheath is removed.  I found that painful as it was done, then the area was achy afterward.  The closure device decreases bleeding and pressure is held at the site for a shorter time.  The patient will then be taken to a recovery area or to their hospital room.  It is necessary to move the site as little as possible for a few hours to minimize the chance of severe bleeding.  Sometimes a pressure device or a sandbag is placed over the site.

After a heart cath, it is important to keep an eye on the puncture site until it heals.  It needs to be kept clean and dry.  Swelling, redness, pain, or bleeding at the site needs to be reported to the doctor right away.  Follow your instructions regarding activity and lifting restrictions and site care.  If all goes well, the puncture should be healed in a few days.

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