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Dual-chamber rate-modulated (DDDR) pacing is a mode that is programmed into a pacemaker and recommended for atrioventricular block and sinus node dysfunction
Dual-chamber rate-modulated (DDDR) pacing is a mode that is programmed into a pacemaker and recommended for patients with atrioventricular block and sinus node dysfunction.
DDDR modes include pacing and sensing capabilities in both the ventricles and atria:
- Dual response to detection (triggering and inhibition)
- Dual-chamber (atrial and ventricular) sensing
- Dual-chamber (atrial and ventricular) stimulation
Mentioned below are four rhythms seen in the DDDR pacing mode:
- No pacing (A sense, V sense) with normal sinus rhythm
- A native QRS (A pace, V sense) with atrial pacing and ventral sensing
- Ventricular pacing (A sense, V pace) with atrial sensing and native P wave
- Ventricular pacing (A pace, V pace) with atrial pacing
DDDR pacing maintains atrioventricular asynchrony not only at rest but also during exercise. The pacemaker follows the fastest rate that can be the intrinsic atrial rate or sensor-indicated rate. Both maximal tracking rate and sensor rate have to be programmed separately.
DDDR pacing requires careful monitoring because there is a high risk of complications associated with the implantation and follow-up procedures. Complications include problems with ventricular leads, ventricular dyssynchrony, and atrial lead dislodgement.
What is a pacemaker?
A pacemaker is a small device implanted in the chest to control the beating of the heart. Electrical impulses from the pacemaker stimulate myocardial contraction and prevent the heart from beating too slowly.
There are three types of pacemakers that can be implanted in the patient depending on their condition:
- Single-chamber pacemaker: Carries electrical impulses to the right ventricle of the heart
- Dual-chamber pacemaker: Carries electrical impulses to the right ventricle and atrium of the heart and controls the timings of contractions between the chambers
- Biventricular pacemaker (cardiac resynchronization therapy): Stimulates both right and left ventricles and helps the heart beat efficiently
How does a pacemaker work?
Pacemakers help store information about the heartbeat, which helps doctors better analyze the condition of the heart. Pacemakers can be divided into two parts:
- Wires (leads or electrodes) that are implanted in the heart and connected to a computer
- A small metal battery-operated computer implanted in soft tissues beneath the skin in the heart
If the heart is beating slowly, the pacemaker monitors the heartbeat and sends electrical energy as programmed to pace the rate. A pacemaker also helps treat symptoms such as fatigue and light-headedness.
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In the U.S., 1 in every 4 deaths is caused by heart disease.
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How is pacemaker surgery performed?
In order to determine the pacing mode needed for the pacemaker, certain tests may need to be ordered. Surgery is then performed in the following steps:
- Before the procedure begins, an intravenous sedative is administered. Anesthesia is usually given to numb the area where the incision is going to take place; general anesthesia can be administered as well.
- The chest is cleaned with a special soap.
- Under or near the collarbone, wires are inserted into the major vein and guided to the heart.
- One end of the wire is secured at an appropriate position in the heart, and the other end is attached to a pulse generator that is implanted under the skin.
- In a single capsule, there is a pulse generator and other pacemaker parts. A catheter is inserted in the vein of the groin, and the pacemaker is moved to the proper position in the heart.
Pacemaker surgery takes a few hours to complete. After the procedure, the patient is required to stay in the hospital for a few hours to be monitored for potential complications.
Patients are advised to avoid strenuous activities that can put pressure on the pacemaker. If a patient observes signs such as infections at the insertion site, swelling, or blood clots, they should seek immediate medical attention.