Chapter 36: Dysrhythmias and Valvular Disorders

Dysrhythmias involve abnormal heart rhythms originating from disrupted electrical conduction and are classified by their anatomical origin and clinical significance. Atrial dysrhythmias include atrial fibrillation, characterized by rapid irregular contractions that eliminate coordinated atrial pumping and create significant risk for thromboembolic stroke, necessitating anticoagulation strategies guided by risk stratification tools such as the CHA2DS2-VASc score. Supraventricular tachycardias comprise rapid rhythms above the ventricular level, often involving reentrant pathways such as those found in Wolff-Parkinson-White syndrome, and respond initially to vagal maneuvers or adenosine administration. Ventricular dysrhythmias range from premature contractions to life-threatening monomorphic and polymorphic ventricular tachycardia, with increased mortality risk particularly in post-myocardial infarction patients. Conduction disturbances or heart blocks obstruct electrical transmission between atrial and ventricular chambers, ranging from asymptomatic first-degree blocks to complete third-degree blocks requiring permanent pacemaker insertion. Valvular disorders result from stenotic narrowing or regurgitant incompetency of cardiac valves, disrupting normal blood flow patterns and creating audible murmurs. Specific pathologies include aortic stenosis producing characteristic crescendo-decrescendo systolic murmurs and left ventricular hypertrophy, mitral stenosis narrowing left ventricular filling, and mitral valve prolapse representing the most prevalent structural valve abnormality. Diagnostic approaches rely heavily on electrocardiographic interpretation and echocardiographic imaging to differentiate pathological murmurs from benign functional murmurs occurring during high-output states. Management strategies differentiate between asymptomatic and symptomatic presentations, employing pharmacological interventions including rate-control agents, vasodilators, and diuretics for medical stabilization, alongside invasive procedures such as valvuloplasty or surgical valve replacement for severe disease. Endocarditis prophylaxis with antimicrobial agents protects high-risk populations from infectious complications following invasive procedures.