The Article, “Can No-Reflow Be Silent” explains what
no-reflow phenomenon is and how it is important in my field of being a
cardiovascular technologist. Explanation of no-reflow will be further discussed
along with the signs and symptoms and treatment in the cardiovascular field.

No-flow phenomenon, also called “slow-flow” is when there is
no blood flow down a vessel that has been treated by stenting, angioplasty, or
other intervention such as Rotablator atherectomy. No-reflow usually occurs when
restoring blood flow in patients with a ST elevation myocardial infarction
(STEMI), stenting degenerated saphenous vein grafts or percutaneous coronary
intervention with thrombus that is distal in the vessel. No-reflow is defined
as a TIMI (thrombolysis in myocardial infarction) grade less than or equal to
2. According to the Article “Can No-Reflow Be Silent”, the frequency of
no-reflow ranges from 12-25%, and studies have showed that 4-7% of the treated
lesions has a TIMI flow less than or equal to 2. Studies have also showed that
higher rates have been noted when using other flow measurements such as
myocardial contrast echocardiography. The TIMI grade scale is used to access
coronary artery perfusion beyond the point of occlusion in the vessel. TIMI
grade 2 stands for partial perfusion in which there is delayed antegrade flow
with complete filling distally. TIMI grade 1 is penetration without perfusion
where there is faint antegrade flow beyond the occlusion with incomplete
filling distally. The last or lowest TIMI grade of 0 refers to no perfusion
beyond the occlusion. With no-reflow having a TIMI grade less than 2, we know
that there is little to no flow distally in the vessel, even after intervening.
With that being said, complications can arise when this happens, like treating
a STEMI patient or working with saphenous vein graft (SVG) interventions.

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No-reflow is considered a
devastating complication with treating ST-elevation myocardial infarction
(STEMI) patient or working with saphenous vein graft interventions. Patients can
present with one of the two types of no-reflow. Reperfusion-related no-reflow
(RNR) and primary no-reflow (PNR). In RNR there is impaired myocardial
perfusion due to epicardial coronary obstruction like there is when a patient
is having a STEMI. If the obstruction is opened after an intervention, distal
myocardial tissue remains compromised. The left ventricular systolic
dysfunction and the size of the infarct is significantly increased with RNR. In
PNR, the normal perfused vessel unexpectedly undergoes no-reflow after
intervention.  In PNR, PCI related
barotrauma is suspected of precipitating distal embolization of atheroma and
thrombus. Obstruction more than 50% of the microvasculature is required to
decrease myocardial blood flow. The rate of no-reflow ranges 0.6% to 2% and is
more commonly observes with the use of stents, atherectomy and PCI in saphenous
vein grafts (SVG).

Patients can
present with signs and symptoms of no-reflow in multiple ways. In the
catheterization lab, the clinical presentation of no reflow in STEMI patients
is sudden and dramatic. You will be able to see the contrast stop in the
coronary artery, then the patient will feel chest pain, and hemodynamic
compromise will follow. The sudden hemodynamic deterioration may be related to atheroembolism
and slowing of blood flow in the healthy arteries.  It is often associated with new or persistent
ST elevation, chest pain, and decreased left ventricular function with low
blood pressure. It is rare for a patient to have no-reflow, and not present
with symptoms such as the ones listed above. These signs and symptoms of
no-reflow doesn’t always present while in the catheterization lab. Some
patients do not have any signs of no-reflow until they are in the holding room
after their intervention has been done, and these are normally less
dramatic.  After thrombolytics are given,
the patient will have ST-segment elevation and may have hemodynamic
deterioration that will lead to new Q waves. No-reflow phenomenon is also
linked to ventricular arrhythmias, early congestive heart failure, and even
cardiac rupture.

I have not personally been involved with a case where
no-reflow was present after intervention. The best approach in treating
no-reflow is to prevent its occurrence in the first place. It can be prevented
or minimized with pharmacological and mechanical pre/post treatment. When
possible, a native vessel PCI should be attempted rather than going after a
severely declining saphenous vein graft with a large thrombus. Minimizing the
door-to-balloon time in an acute MI reduces the chances of RNR. During stenting
of high risk lesions, inflations should be of low diameter and pressure which
would minimize distal embolization. Patients can be pretreated with
intracoronary calcium channel blockers for the treatment of saphenous vein
grafts. During rotational atherectomy, no-reflow can be prevented by lowering
rotational speed to around 140,000 rpm. Pharmacological preventive measures
during rotational atherectomy include abciximab, intra-coronary adenosine, and
a cocktail including nitrate, verapamil, and heparin. The treatment for no
reflow depends on what is causing the no reflow, so it can be treated in a few
different ways. If no reflow is due because of plaque rupture causing thrombus
distally in the vessel, catheter aspiration is done to vacuum the clot out.
Additional anticoagulants such as heparin, ReoPro, or Aggrastat should be given
and rechecking activating clotting time levels is necessary. If no reflow is
due to a dissection, then additional stenting down the vessel is required. If
no reflow is due to severe spasm, nitroglycerin (100mcg/cc) is recommended to
relieve the spasm but it has not been shown to help no-reflow phenomenon unless
given in 100 microgram boluses multiple times. Inserting distal protection
devices or proximal protection is the most common mechanism when performing
interventions on saphenous vein grafts or acute STEMIs. This can help reduce
clots and prevent no reflow from happening.

No reflow phenomenon, as well as most other cardiovascular
complications are still being studied for the best treatment. Every patient is
different when treating these issues but the treatments listed in the above
paragraph are the cardiovascular teams “go-to” when treating no-reflow
phenomenon. Filters are still being tested in STEMI but are not standard,
however it is always better to be prepared for the worst.

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