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:
- Chest pain
- 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
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.
Monomorphic Ventricular Tachycardia
Symptoms associated with MVT include:
- Palpitations, often described as pounding, racing, or fluttering
- Chest pain or tightness
- Presyncope or syncope
- Cardiac arrest
Signs on exam:
- achycardia with narrow QRS complex on ECG (rate usually 140-250 bpm)
- Hemodynamic instability – hypotension, acute heart failure
Associated risk factors and conditions:
- Structural heart disease – prior myocardial infarction, cardiomyopathy
- Electrolyte abnormalities – hypokalemia, hypomagnesemia
- Drugs that prolong QT interval
- Congenital syndromes – long QT syndrome, Brugada syndrome
- Men are more commonly affected than women
- Mean age of presentation is 65 years old
MVT can present across a spectrum from asymptomatic ectopy to unstable rhythms causing syncope, chest pain, shortness of breath, hypotension, or sudden cardiac death. It is crucial to obtain a 12-lead ECG, which will demonstrate a regular, monomorphic wide complex tachycardia. Hemodynamic instability warrants urgent electrical cardioversion.
Polymorphic Ventricular Tachycardia
- Symptoms associated with polymorphic VT include palpitations, lightheadedness, syncope, and chest pain. Hemodynamic instability with hypotension, altered mental status, and shock can occur.
- Polymorphic VT often presents with a rapid ventricular rate between 150-250 beats per minute.
- The ECG shows a irregular, continuously changing QRS morphology and axis – the complexes appear to twist around the isoelectric line.
- Prolongation of the QT interval is usually seen prior to initiation of polymorphic VT episodes.
- Risk factors include structural heart disease, electrolyte disturbances (hypokalemia, hypomagnesemia), drugs that prolong QT interval, bradycardia, pauses, congenital long QT syndromes.
- More common in older adults but can occur at any age. Slight male predominance.
- Sudden cardiac death can be the initial presentation in patients with undiagnosed congenital channelopathies.
- Syncope, cardiac arrest, or sudden death can occur if polymorphic VT deteriorates into ventricular fibrillation.