Human heart

The heart has a specialised nodal (cardiac) musculature that generates and conducts the impulse.
It consists of the sino-atrial node (SAN), the atrio-ventricular node (AVN), the atrio-ventricular bundle, its right and left branches and the Purkinje fibres.
The atrio-ventricular bundle continues from the AVN, passes through the atrio-ventricular septa and divides into right and left bundles; together with the Purkinje fibres these are known as the bundle of His.
It conducts the impulse from the AVN to the ventricular muscles.
Hence the bundle of His is a part of the heart.

The tricuspid valve guards the opening between the right atrium and the right ventricle.
The chordae tendinae are tendinous cords that attach the flaps of the valve to the papillary muscles of the ventricle; they keep the flaps from turning back into the atrium when the ventricle contracts.
If they are partly non-functional, the valve will not close properly during ventricular systole and some blood will leak back into the right atrium.
Less blood will then be pumped from the right ventricle into the pulmonary artery.
The aorta and the left atrium are on the left side of the heart and are not directly affected, and the pacemaker (SA node) is independent of the valve.
Hence the flow of blood into the pulmonary artery will be reduced.