ventricular contractions (PVCs) are extra, abnormal heartbeats originating in the ventricles.
They disrupt the heart's regular rhythm and typically have not been a
reason for concern.
However, recent research has demonstrated
that PVCs are an important predictor of heart failure and mortality and
can cause very bothersome symptoms. Further, such early beats occurring
continuously for more than 30 seconds is a potentially serious cardiac
condition called ventricular tachycardia (VT).
‘A common treatment for irregular heartbeats known as catheter ablation may result in the formation of brain lesions when it is performed on the left side of the heart.’
A common treatment for irregular heartbeats known as catheter
ablation may result in the formation of brain lesions when it is
performed on the left side of the heart, according to new research at UC
San Francisco. Importantly, there also is evidence these lesions may be
associated with cognitive decline, meaning they may not be benign.
In a small study of patients undergoing catheter ablation for common
abnormal heartbeats from the lower chamber of the heart, researchers found a significantly
higher rate of seemingly asymptomatic brain injury due to embolism among
the patients whose therapy occurred on the left ventricle of the heart,
which supplies blood to the brain, compared to patients whose therapy
was conducted on the right ventricle, which pumps blood to the lungs.
The researchers recommend further study on the impact of these
lesions and strategies to avoid them. Their study appears online January
24, 2017, in the American Heart Association journal Circulation
"The rate of asymptomatic emboli in similar procedures for other
types of heart rhythm disturbances tends to be 10-20%," said
study senior author Gregory Marcus, a UCSF Health cardiologist
and director of clinical research in the UCSF Division of Cardiology.
"Our study finding is relevant to a large number of patients
undergoing this procedure and hopefully will inspire many studies to
understand the meaning of and how to mitigate these lesions," Marcus
said. "This also will become an important consideration as we think
about how to optimally help the large number of people out there with
Given growing recognition of all these phenomena, catheter ablation
for PVCs and VT is mainstream and becoming even more common, with well
more than 235,000 such procedures performed annually. It is also
increasingly used for patients with heart failure due to weak heart
muscle that may improve after frequent PVCs are eradicated.
In this minimally invasive procedure, thin, flexible wires called
catheters are inserted into a vein and threaded into the heart. The tip
of the catheter either delivers heat or extreme cold to destroy tissue
responsible for starting or maintaining the abnormal heart rhythm. The
procedure can result in the complete and permanent cessation of the
PVCs/VT that are targeted and is generally considered low risk.
An "embolism" occurs when an object moves through the bloodstream
from one part of the body to another. Catheters placed in the left side
of the heart may lead to brain injury if something that can occlude a
blood vessel is either formed, such as a blood clot, or dislodged by the
catheter and travels to the brain. Because the right side of the heart
leads to the lungs, not the brain, brain emboli generally are not a
Data from previous left heart-based procedures has shown that brain
injury thought to be due to embolism rarely occurs. Those emboli
generally have been attributed to either issues with the particular
patient populations studied or the risks inherent to treating another
common heart rhythm disturbance, atrial fibrillation, with ablation.
In this Circulation
study, Marcus and his colleagues enrolled
18 patients scheduled for VT or PVC ablation over a nine-month period.
The average patient age was 58, with half being men, half having a
history of hypertension, and a majority having no known vascular disease
or heart failure. Most patients were generally healthy.
Left ventricular (LV) ablation was performed in 12 patients compared
to a control group of six patients who underwent right ventricular (RV)
ablation. Pre- and post-procedural brain magnetic resonance imaging
(MRI) was performed on each patient within a week of the ablation, along
with a complete neurological examination.
Overall, seven of the 12 patients (58%) who underwent LV
ablation experienced 16 brain embolisms combined, compared to zero
patients who underwent the RV ablation. Seven of 11 patients (63%) who underwent a retrograde approach to their LV ablation
developed at least one new brain lesion.
"Further research is important to understanding the long-term
consequences of these lesions and determining optimal strategies to
avoid them," said lead author Isaac Whitman, UCSF cardiac