Week 5: A Case Worth Noting

It started with drugs.  The list of pharmaceuticals circulating in the patient’s bloodstream was impressive.   Out on the streets, the same substances would undoubtedly have any narcotics cop reaching for handcuffs.  As I stood in the hospital ward watching my mentor question a patient prior to a procedure scheduled for that day, I could see that the pain medication was affecting the patient’s ability to focus.  The patient answered the questions appropriately, but the answers seemed to require exhaustive effort, given in a barely audible mumble.  Besides the medications, the patient’s chart indicated a number of other issues.

Most notably, the patient’s white count was high indicating possible infection, which in general is a contraindication for any sort of surgical procedure.  However, Dr. Sista was uncertain that the patient would become any more stable with time.  A quick phone consultation with the primary care physician confirmed that the high white count and lethargy had become the patient’s baseline.  Dr. Sista decided to proceed.

An hour before the patient even arrived, the preparations began.  I talked to the anesthesiologists as they set up their ventilator. Thinking that the painkillers already in the patient’s system would at least partially combat the pain associated with the procedure, I asked the anesthesiologists if they would need to use a lower dose for this case.  Surprisingly, I learned that the opposite was true.  Long-term use of pain medication had increased the patient’s tolerance to the drugs to the point that a higher dose would likely be needed to keep the patient asleep. 

As the physicians entered the angiosuite to begin the procedure, a final check of the patient’s vitals and lab results revealed another surprise.  The patient’s creatinine levels were abnormally high.  Creatinine is a protein filtered by the kidneys and is used as a marker of renal function.  The high levels indicated a reduced ability of the patient’s kidneys to filter toxins from the bloodstream.  Consequently, the amount of contrast agent injected into the patient had to be severely limited if not eliminated altogether.  Contrast is the dye that enables interventional radiologists to visualize arteries and veins that would otherwise be invisible on the fluoroscope.  Without contrast, I half expected the procedure to be cancelled.  However, Dr. Sista barely hesitated, instead requesting that a CO₂ tank be brought to the room.  Carbon dioxide naturally is of much lower density than blood or tissue and does not attenuate x-rays.  Consequently, compared to the surrounding tissue the CO₂ gas would appear bright white on the flouroscope.  Furthermore, CO₂ rapidly dissolves in the bloodstream and is later exhaled through the lungs without affecting kidney function.

With the patient’s peculiar challenges handled, the procedure began.  Entering through the femoral vein with an intravascular ultrasound (IVUS) catheter, Dr. Sista investigated the patient’s vessels from the inside looking for clots and other obstructions to blood flow.   Even with my limited experience, I was shocked at how narrow the vessels appeared to be, sometimes not much larger than the catheter itself.  Furthermore, gray splotches within the otherwise black lumen of the vessel indicated the presence of clots.  Wielding a device not unlike the coils used by plumbers to clear blocked pipes, Dr. Sista attempted to physically break apart the clot while simultaneously injecting tissue plasminogen activator (tPA), an anticoagulant.  Unfortunately, a second investigation of the vessel with IVUS revealed that the thrombosis had only worsened and the vessel was as obstructed as ever.

In order to hold the vessel open, stents were clearly needed.  However, a stent cannot be effective unless it is exposed to free flowing blood.  Thus, to place the stents, the precise position of the thrombosis needed to be identified.  Finding the first open area of vasculature upstream of the clot with the IVUS, Dr. Sista turned to the flouroscope to visualize the IVUS tip.  The x-ray image revealed that in order to reach a clear lumen, the catheter had been drawn all the way back into the sheath used to access the vessel in the first place.  In other words, there was no point downstream of the point where the femoral vein had been accessed that was sufficiently clear for stent placement.  Another access point was needed. 

Withdrawing the catheters and wires from the femoral access point, the physicians rapidly cleaned and prepared the patient’s neck for a jugular vein access.   As the access wire slid through the patient’s inferior vena cava (IVC) toward the obstructed vessel, a familiar basket-like device appeared on the flouroscope screen.  It was an IVC filter, a device designed to catch clots before they can make their way to the heart, lungs and other vital organs and potentially resulting in a deadly embolism.  With the build-up of thrombus in the patient’s vasculature, the filter was more critical than ever, but it now stood in the path that Dr. Sista needed to traverse in order to stent the obstructed vessel.  Maneuvering as carefully as possible, Dr. Sista and the assisting fellow began ballooning open the vessel and positioning stents.  Despite their care, a balloon caught the filter as it was extracted, knocking the filter askew.  As soon as all the stents were in place, Dr. Sista extended a new device into the patient’s IVC, known as a tip deflecting wire.  As the name suggests, a tip deflecting wire can be bent around corners by deflecting the wire tip with a specialized handle at the wire’s opposite end.  Curving around the deformed IVC filter, Dr. Sista managed to push it back into its original position.  Not wanting to leave a potentially damaged filter inside the patient, he removed it with a lasso-like snare in a process I had seen several times as its own procedure, and replaced it with a new one. 

With stents in place, the blood flow was restored to some extent, but was not yet perfectly clear. The patient remained pro-thromobotic, forming clots faster than they could be removed.  Throughout the procedure, the patient was given repeated injections of heparin, a protein that helps prevent clot formation yet it wasn’t enough.  Dr. Sista prescribed lovenox, a drug used to treat deep vein thrombosis as well as other blood clots, and decided to observe the patient over the next couple of days. 

Later in the week I saw the patient again during morning rounds.  Due to tachycardia (high heart rate) and hypotension (low blood pressure) the patient had remained intubated (the breathing tube used to anesthetize the patient was kept in place) since the procedure, but was being weaned off the ventilator and was scheduled to be extubated (have the tube removed) that day.  I can only hope that as time passes the patient’s condition continues to improve.