Final answer:
The diagnosis of an arrhythmia through ECG involves understanding the normal electrical conduction established by the SA node, recognizing abnormal patterns and frequencies on the ECG for atrial fibrillation or SVT, and identifying PVCs by their distinct wide QRS complexes.
Step-by-step explanation:
Diagnosing the correct cardiac arrhythmia on an electrocardiogram (ECG) requires an understanding of the normal electrical conduction of the heart, as well as the characteristics of various arrhythmias. The normal heart rhythm, established by the sinoatrial (SA) node, is called sinus rhythm. This rhythm results in the methodical contraction of the heart muscle, indicated by a normal sequence in an ECG that includes a P wave, followed by a QRS complex and a T wave for each heartbeat. In arrhythmias like atrial fibrillation, the ECG demonstrates an abnormal, irregular electrical pattern prior to the QRS complex and an increased frequency between QRS complexes. Atrial flutter would show a sawtooth-like pattern in the atrial activity, but is not characterized by increased frequency between the QRS complexes. Supraventricular Tachycardia (SVT) shows a rapid series of consecutive QRS complexes without noticeable P waves. If premature ventricular contractions (PVCs) are present, this would be evident by abnormal, wide QRS complexes at irregular intervals. Therefore, for a diagnosis involving atrial fibrillation with PVCs or SVT with PVCs, we would look for such ECG signs in deciding between options B and D.