A DDDR pacemaker takes over some of the heart's natural pacemaker functions when this organ is not beating correctly. Sometimes called a dual chamber rate adaptive pacemaker, it can be programmed by a cardiologist specifically for the patient, to apply just the pacing needed to make up for the heart's insufficiency, and it can work in both the right and left ventricles. A DDDR pacemaker also can work in the right and left atriums of the heart, which are the reservoirs of blood for the ventricles. It is said to be rate adaptive as it can adjust and regulate pacing automatically. This is one of the most commonly used types of pacemakers, as it can address the widest range of heart pacing issues.
The letters DDDR identify the type of pacemaker it is, according to what are called NBG codes or Generic Codes categorizations that have been set up by two medical pacing and electrophysiology groups in North America and Britain. These letters correspond to the functions or uses of a DDDR pacemaker. The letters mean Dual chamber-paced, Dual chamber-sensed, Dual response, and Rate modulated.
Since this pacemaker is designated as dual chambered, it has wires to both an atrium and a ventricle, pacing each as the heart's natural pacemaker would. Placed between the fat of the chest area and the underlying muscles and bones, it is usually powered by a lithium battery. There, a sensing amplifier receives input from electrodes of what pacing the heart is doing on its own, and then modifies by means of its output circuitry any correcting pulses needed through those same electrodes. Once corrective pulses have corrected atrial arrhythmias, for instance, the pacemaker returns to its listening, tracking, and sensing activity once again.
These functions of the DDDR pacemaker are programmed into the device by the cardiologist by means of what are called automatic mode-switching algorithms for both the atria and the ventricles. The cardiologist can choose which algorithms to use according to the individual patient's heart conditions. Then, beat after beat, the heart is regulated as it normally would have been, if its own natural pacemaking ability had not been compromised. Pacemakers can be recalibrated remotely on an outpatient visit by the cardiologist after implantation, when or if conditions change. DDDR pacemakers also keep a record of all anomalies, which can be extracted by the cardiologist during an outpatient visit thorough a process called pacemaker interrogation.