Chapter 7: Dysrhythmia Interpretation and Management

The heart's conduction system, initiated by pacemaker cells with automaticity, progresses sequentially through the sinoatrial node, atrioventricular node, bundle of His, and Purkinje fibers, with each component serving specific functions including impulse generation, conduction delay for ventricular filling, and rapid signal propagation. The autonomic nervous system modulates this process through sympathetic and parasympathetic influences on heart rate and contractility. Interpreting electrocardiographic recordings requires understanding standardized grid measurements, recognizing normal waveforms including the P wave, QRS complex, and T wave, and measuring critical intervals such as the PR interval and QT interval, which have defined ranges and whose abnormalities signal underlying pathology. Systematic dysrhythmia assessment involves evaluating heart rate using multiple calculation methods, determining rhythm regularity, measuring intervals precisely, and correlating findings with clinical symptoms of hemodynamic compromise such as hypotension or altered consciousness. Dysrhythmias are classified by their anatomical origin: sinus rhythms encompassing bradycardia and tachycardia; atrial dysrhythmias including the commonly encountered atrial fibrillation with its thromboembolic risks and atrial flutter; junctional rhythms originating from atrioventricular nodal tissue; ventricular dysrhythmias ranging from premature contractions to the immediately life-threatening ventricular fibrillation; and conduction blocks categorized by degree and location. Management approaches vary significantly based on dysrhythmia type and patient tolerance, ranging from careful observation to immediate interventions such as defibrillation. The chapter concludes with pacemaker technology, distinguishing temporary and permanent devices, explaining the meaning of pacer spikes on electrocardiographic tracings, identifying normal pacing patterns, and recognizing malfunction states including failure to pace, failure to capture, and failure to sense, all critical knowledge for critical care nurses providing comprehensive patient monitoring and safety.