Introduction:
The cardiac pacemaker, responsible for initiating and regulating the heartbeat, can sometimes fail to function normally. In such cases, an artificial pacemaker is often grafted into the patient to restore the normal rhythm of the heart. The location at which the artificial pacemaker is to be grafted depends on several factors, including the specific site of the malfunction and the desired outcome.

(a) Atrioventricular Bundle:
The atrioventricular (AV) bundle, also known as the Bundle of His, is a specialized bundle of fibers that conducts the electrical signals from the atria to the ventricles. Grafting an artificial pacemaker at the side of the AV bundle would allow for the electrical impulses to be directly transmitted to the ventricles, bypassing any malfunctioning components. However, this location is not commonly chosen for pacemaker grafting due to the technical difficulties associated with accessing and implanting the pacemaker leads in this region.

(b) Purkinje System:
The Purkinje system consists of specialized fibers that transmit electrical impulses rapidly throughout the ventricles, allowing for coordinated contraction. Grafting an artificial pacemaker within the Purkinje system would ensure efficient and synchronized activation of the ventricles, overcoming any malfunctioning of the natural pacemaker. However, this location is also not commonly chosen for pacemaker grafting due to the technical challenges and potential complications associated with accessing and implanting the leads within the intricate network of Purkinje fibers.

(c) Sinoatrial Node:
The sinoatrial (SA) node is the natural pacemaker of the heart, responsible for initiating the electrical impulses that regulate the heartbeat. If the SA node fails to function normally, grafting an artificial pacemaker at the site of the SA node can effectively take over the role of initiating and regulating the heartbeat. This is the most common location for pacemaker grafting as it allows for easy access and implantation of the leads. The artificial pacemaker would generate electrical impulses that stimulate the atria, ensuring proper contraction and coordination of the heart.

(d) Atrioventricular Node:
The atrioventricular (AV) node acts as a relay station between the atria and the ventricles, slowing down the electrical impulses before they are transmitted to the ventricles. In cases where the AV node fails to function properly, grafting an artificial pacemaker at the side of the AV node can help regulate the electrical conduction from the atria to the ventricles. This location is less common for pacemaker grafting compared to the SA node, as it may result in a slower heart rate due to the AV node's intrinsic delay in conduction.

Conclusion:
In the given scenario, if the patient's cardiac pacemaker fails to function normally, the most likely location for grafting an artificial pacemaker would be at the site of the sinoatrial (SA) node. This ensures the proper initiation and regulation of the heartbeat. However, the final decision regarding the specific location for pacemaker grafting would depend on the individual patient's condition and the recommendations of the treating physicians.