Clinical Presentation: Supraventricular Arrhythmias

Atrial Fibrillation

The clinical manifestations of AF span a wide spectrum. Some patients are completely asymptomatic while others experience severe, debilitating symptoms related to rate, irregularity, and loss of atrial contraction:

• Palpitations
• Dyspnea
• Fatigue
• Dizziness
• Chest pain
• Polyuria
• Exercise intolerance

Symptoms like palpitations and dyspnea correlate with higher ventricular rates. Rapid, uncontrolled rates can precipitate myocardial ischemia, heart failure exacerbation, hypotension, and cardiomyopathy. Irregular R-R intervals also reduce cardiac output. Loss of atrial kick further compromises hemodynamics, especially in patients with diastolic dysfunction or conditions like mitral stenosis that rely heavily on atrial contraction.

• Risk factors: hypertension, obesity, smoking, cardiac disease, diabetes, chronic kidney disease, alcohol consumption, sleep apnea
• Signs: irregularly irregular pulse, rapid ventricular response

Supraventricular Tachycardia– AVNRT

Patients with AVNRT typically present with sudden onset palpitations, often described as a “pounding” or “racing” sensation in the chest. Episodes most often start and stop abruptly, lasting from a few seconds to hours. Other associated symptoms may include dizziness, lightheadedness, dyspnea, chest pain, and anxiety. Syncope can occur but is less common than in AVRT. Some patients may be asymptomatic and the tachycardia is discovered incidentally on ECG.

AVNRT can occur at any age but is most prevalent in middle-aged adults, with a mean age of onset around 50 years. There is a strong female predominance, with 60-80% of cases occurring in women. Many patients have no structural heart disease, however AVNRT can also occur in patients with underlying cardiovascular conditions. Triggering factors include caffeine, alcohol, exercise, emotional stress, fever, electrolyte imbalances, and medications including digoxin, beta-agonists, and antiarrhythmics.

On physical exam during an acute episode, typical findings include a rapid but regular pulse rate, normal blood pressure, and no murmurs, rubs, or gallops. Jugular venous pressure may be elevated due to impaired ventricular filling time. Abrupt termination of the episode may result in a brief pause before resumption of normal sinus rhythm. Some patients may develop hypotension or other signs of hemodynamic instability during prolonged episodes.