Cardiac resynchronization therapy
What is cardiac resynchronization therapy and how is it done
Some patients with heart failure develop ventricular conduction blocks,
which makes the contraction and relaxation of the left and right
ventricles asynchronous, which exacerbates the symptoms of heart failure.
The ventricular resynchronization rhythm regulator developed in recent
years can be set to make the left and right ventricles contract
synchronously and strengthen the function of the heart.
This therapy differs from traditional pacemakers in that the stimulation
of the ventricles is only initiated by the right ventricle, so the activation
of the entire ventricle is conducted from the right ventricle to the
the left ventricle, which is quite different from normal physiology.
In synchronous therapy, wires are placed in the left ventricle
(entering through the coronary sinus of the right atrium and placed on
the vein on the surface of the left ventricle) and the right ventricle by
way of cardiac catheterization to achieve synchronous contraction of the
left and right ventricles.
Current research shows that this treatment is helpful for left ventricular
systolic function, heart failure symptoms, exercise tolerance,
and quality of life, and the number of rehospitalizations of patients due
to worsening heart failure can also be significantly reduced. In terms of
health insurance payment, this treatment is currently subject to prior review,
and the medical department needs to submit it for review in advance,
and then the National Health Insurance Bureau decides to approve the device.
What kind of patients are suitable for cardiac resynchronization therapy?
Consideration may be given to patients with the following conditions:
■Symptoms of heart failure with poor left ventricular systolic function
and difficulty controlling drugs (required)
■With abnormal ventricular conduction function
■Left bundle branch block (LBBB) with QRS duration > 130 milliseconds.
■Non-LBBB, and QRS duration > 150 milliseconds.
■Combined atrioventricular block (AV block) is expected to be highly dependent
on pacemaker stimulation of ventricular contraction, and resynchronization
stimulation will be superior to traditional pacemakers at this time.
What are the possible complications?
Since resynchronization therapy adds a lead from the left ventricle to a
conventional pacemaker, the complications are similar and include:
■Infection
■Wound hematoma
■The lead is displaced so that reoperation is required
■Pneumothorax
■Pericardial effusion
Medical treatment is changing with each passing day. In recent years, many new drugs
have injected vitality into the treatment of heart failure. However, there are still
a large number of patients still suffer from heart failure after appropriate
drug treatment. At this time, patients can discuss with outpatient physicians.
If they meet the indications for cardiac resynchronization therapy, they can be
referred to the outpatient department of cardiology for evaluation. Through this
Treatment to improve the quality of life and achieve the effect of
increasing cardiac output.
Development History
Cardiac pacing has been used to treat chronic heart failure for 30 years [1] :
In 1990, Hochleitner et al proposed that the use of double-chamber pacing and
the short atrioventricular interval could improve cardiac function, which marked
the beginning of the era of cardiac pacing in the treatment of heart failure.
In 1998, the American College of Cardiology ( ACC )/ American Heart Association
(AHA) pacing guidelines listed drug-refractory heart failure as a Class IIb
indication for pacing. In 1998, Daubert et al. first successfully implanted a
left ventricular epicardial pacing leads through the cardiac vein, realizing synchronous
pacing of the left and right ventricles.
In 2001, the first commercial biventricular pacing device came out in the United States
and was approved by the US Food and Drug Administration ( FDA ) the following year.
Clinical trials such as Path-CHF, Insync, MUSTIC, and MIRACLE were carried out during
and after that, which proved that biventricular pacing can improve the cardiac function
and quality of life of patients with chronic heart failure with prolonged QRS duration.
In 2002, ACC/AHA/NASPE listed chronic heart failure with prolonged QRS duration as a Class
II indications for CRT.
and the CARE-HF study in 2005 showed that CRT can not only improve the symptoms of
chronic heart failure, reduce the hospitalization rate, but also significantly
reduce the mortality rate.
In 2005, the guidelines for the treatment of chronic heart failure formulated by the
European Society of Cardiology (ESC) and ACC/AHA successively listed some chronic
heart failure with cardiac asynchrony as Class I indications for CRT.
In 2007, the ESC guidelines for cardiac pacing and resynchronization therapy and the
2008 ACC/AHA/American Heart Rhythm Society (HRS) guidelines for the treatment of
abnormal cardiac rhythm devices both defined left ventricular ejection fraction
(left ventricular ejection fraction, LVEF) decline and QRS time limit Prolonged
heart failure patients are listed as Class I indications for CRT, which fully affirms
the therapeutic significance of CRT again.
In 2010, the ESC guidelines for the treatment of chronic heart failure devices
listed mild heart failure patients with cardiac function class II ( NYHA classification )
as Class I indications for CRT for the first time.
for the Treatment of Abnormal Cardiac Rhythm Devices listed some patients with mild heart
failure as Class I adaptations of CRT. At the same time, it is emphasized that patients
with left bundle branch block (LBBB) pattern benefit most from CRT, and there are stricter
requirements for the QRS duration in class I indications.
In 2013, the 2013 ESC/European Heart Rhythm Association (EHRA) guidelines for cardiac
pacing and cardiac resynchronization therapy, the 2016 ESC guidelines for the diagnosis
and treatment of acute and chronic heart failure and the 2018 ACC/AHA/HRS bradycardia
re-emphasized the characteristics of the CRT class I indication population, namely LBBB
pattern and prolonged QRS duration. At the same time, the indication levels for specific
populations such as patients with atrial fibrillation, patients with upgraded pacemakers,
and patients with a high proportion of ventricular pacing but mildly decreased LVEF were defined.
principle
Cardiac resynchronization therapy adds left ventricular pacing based on traditional
dual-chamber pacing. The left ventricular pacing electrode passes through the opening of the
coronary sinus of the right atrium and enters the posterior wall of the coronary vein and the
lateral branch of the left ventricle to pace the left ventricle. , through left and right
ventricular electrode pacing to restore ventricular synchronous contraction
and reduce mitral regurgitation.
complication
The complications of cardiac resynchronization therapy implantation are higher than
those of ordinary pacemakers. Except for the complications similar to conventional
pacemaker implantation, the complications of cardiac resynchronization therapy are
mainly related to left ventricular pacing leads and coronary sinus.
1. Coronary sinus dissection and perforation
Coronary sinus dissection can be caused by pushing the tip of the guiding catheter
or injecting contrast material too violently against the vessel wall. Coronary sinus
dissection occurs in 2% to 5% of cases but usually heals well. Coronary sinus perforation is rare.
2. Left ventricular lead dislocation
Left ventricular leads have a higher rate of dislocation than atrial or right
ventricular leads and dislocation tend to occur shortly after insertion.
3. Puncture bleeding, nerve injury
Insertion of wire through subclavian vein puncture has been widely used in clinical practice.
Although it is relatively safe and simple, it still needs to be vigilant. The main complications
include mispunctuate of the subclavian artery, hemothorax, pneumothorax,
hemopneumothorax, nerve injury, etc.
4. Infection
The incidence of infection for the first insertion is 0.5% to 1% but prolonged
operation will increase the risk.
5. Phrenic nerve stimulation
Phrenic nerve irritation is a common problem that may not be readily apparent in sedated and supine
patients at insertion and may only become apparent when the patient moves and changes position.
0 Comments