The Expert: Dr. Carolyn Brockington, M.D., a neurologist based at New York’s Mt. Sinai Hospital, testifies as to the propriety of the defendant neurologist’s treatment.
In a 2016 trial over claims medical negligence led a patient with deep vein thrombosis to suffer a stroke, Dr. Carolyn Brockington, a vascular neurologist from New York’s Mt. Sinai Hospital, testified for the defense. In this clip, her testimony focuses on the use of the anticoagulant heparin to prevent strokes in patients who have existing blood clots, as well as the purpose, timing, and placement of a vena cava filter in such a patient.
A key question the defense attorney raises, and likely one in jurors’ minds, is how post-stroke placement of a vena cava filter, meant to trap blood clots, could be within the standard of care. With clarity of voice and mind, Brockington assures the jury that the defendant used “first-line therapy” by treating the patient with intravenous heparin before the stroke. The patient was known to have had a deep vein thrombosis and a pulmonary embolus, a blood clot that travels to the lung and gets caught there, as well as a transient ischemic attack, or TIA, the result of a clot travelling to the brain arteries that briefly caused neurologic symptoms. All of these can be the result of a hypercoagulable state, and the standard of care provides that intravenous heparin is used as the primary treatment to prevent further clotting consequences in such a situation.
The use of an IVC [inferior vena cava filter] filter was not indicated at that point, Brockington says, but when the patient subsequently suffered a stroke, the treating physician reconsidered. Since there was evidence of internal bleeding requiring transfusions while the patient was on heparin, as signified by a drop in blood count and retroperitoneal hemorrhage noted on a CAT scan, the treating physician decided to discontinue the anticoagulant heparin and have an IVC filter placed to prevent further embolisms from the large deep veins of the lower extremities. The testifying expert says this was “absolutely” the right thing to do. A physician should not continue to give an anticoagulant to an actively bleeding patient, even if not giving it leaves the patient at risk for clotting episodes. Placing the IVC filter would provide an impediment to further embolic phenomenon, although it would have no effect on the patient’s natural ability to clot anywhere in the body.
In explaining these choices, Brockington discusses how heparin works. Clotting causes sluggish blood flow and attracts more clots, thus propagating the clot, in other words, making it become longer. These long clots then have a propensity to break off near their ends, which creates a travelling clot or embolism. Heparin is designed to prevent the propagation and thus decrease the chance of embolization throughout the body. The testifying expert then contrasts that with the IVC filter, which does not prevent blood clotting, but solely prevents clots that have already formed from moving beyond it.
Since this filter was placed at the level of the pelvis, it could only stop those clots that existed below it and were attempting to move above it. The filter would have no effect on stopping clots from forming elsewhere in the body, nor could it stop an embolism from originating in other areas that formed clots.
Brockington cautions that the IVC filter will not stop all clots from getting through the device. Very small clots can still pass through and cause embolic phenomenon. She further describes how very small clots can cause catastrophic strokes. A small but critical area of the brain may be deprived of its circulation, yet have a more profound effect on body function than a larger, but less critical area would. “Location, Location, Location,” she says, will determine the clinical extent of the damage, not the size of the area deprived of blood flow. Silent strokes can occur if the location of the circulatory disruption is so inconsequential that it goes unnoticed by the patient. Both silent strokes and catastrophic stokes, which result in permanent brain injury, can be caused by clots as small as 2mm, depending upon the area that is affected.
This patient had a TIA two days prior to her stroke. The vascular neurology specialist explains that something temporarily interrupted the blood flow to a part of the patient’s brain at that time, and this should never happen even for a moment. The treating physician appropriately took this as a sign that the patient was at high risk for a stroke, and started heparin. The heparin was stopped once the patient had bleeding complications, but once those bleeding complications resolved, it became appropriate to place the patient back on an anticoagulant since the IVC filter will do nothing to prevent the body from developing clots in other places, or small clots that can get through the filter.
A verdict for the defense in this case was certainly influenced by Brockington’s authoritative demeanor, her depth of knowledge, and her logic as she carried the torch for the accused physician.
Gary Gansar, MD, is residency-trained in general surgery. He served as Chief of Surgery and Staff at Elmwood Medical Center and on the Medical Executive Committee at Touro Infirmary and Mercy Hospital in New Orleans, LA. Dr. Gansar was Board Certified in general surgery while in active practice. He joined AMFS in 2015 as a Physician Medical Director.
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