What are the implications and management of tachycardia?

Tachycardia at 135 bpm: Implications and Management

A heart rate of 135 beats per minute indicates a clinically significant tachycardia that requires prompt evaluation for underlying causes and appropriate management based on the specific mechanism and patient stability. 1

Classification and Initial Assessment

• Tachycardia is defined as a heart rate exceeding 100 beats per minute, with 135 bpm representing a moderate to severe elevation that warrants clinical attention 1
• Initial assessment should focus on patient stability, including signs of hypoperfusion, hypotension, altered mental status, chest pain, or heart failure 1
• Determine if the tachycardia is the primary cause of symptoms or secondary to an underlying condition (fever, dehydration, pain, etc.) 1
• Heart rates >150 bpm are more likely to directly cause hemodynamic compromise, but 135 bpm can still be clinically significant, especially with underlying cardiac dysfunction 1

Diagnostic Approach

• Obtain a 12-lead ECG to differentiate between:
  • Narrow-complex tachycardias (QRS <0.12 seconds): sinus tachycardia, atrial fibrillation, atrial flutter, AVNRT, accessory pathway-mediated tachycardia, atrial tachycardia 1
  • Wide-complex tachycardias (QRS ≥0.12 seconds): ventricular tachycardia, SVT with aberrancy, pre-excited tachycardias 1
• Assess rhythm regularity - regular tachycardias suggest sinus tachycardia, AVNRT, or VT; irregular rhythms suggest atrial fibrillation or multifocal atrial tachycardia 1

Common Causes of Tachycardia at 135 bpm

• Physiological sinus tachycardia: fever, dehydration, anemia, heart failure, hyperthyroidism, pain, anxiety 1
• Inappropriate sinus tachycardia: unexplained by physiological demands, often with symptoms of weakness, fatigue, lightheadedness 1
• Supraventricular tachycardias: AVNRT, AVRT, atrial tachycardia 1
• Atrial fibrillation or flutter with rapid ventricular response 1
• Ventricular tachycardia (especially in patients with structural heart disease) 1

Management Based on Stability and Mechanism

For Unstable Patients (hypotension, altered mental status, shock, acute heart failure)

• Immediate synchronized cardioversion is indicated regardless of the specific tachycardia mechanism 1
• If ventricular fibrillation or pulseless VT develops, proceed with unsynchronized defibrillation 1

For Stable Patients with Regular Narrow-Complex Tachycardia

• First-line: Vagal maneuvers (Valsalva, carotid sinus massage) 1
• If unsuccessful, adenosine IV (6 mg rapid push, followed by 12 mg if needed) 1
• Alternative agents: beta-blockers (metoprolol) or calcium channel blockers (diltiazem, verapamil) 1
• Caution: Avoid AV nodal blocking agents in suspected pre-excited atrial fibrillation/flutter 1

For Stable Patients with Regular Wide-Complex Tachycardia

• Presume ventricular tachycardia until proven otherwise, especially with structural heart disease 1
• Amiodarone 150 mg IV over 10 minutes (can repeat as needed) 1
• Procainamide 20-50 mg/min until arrhythmia suppression (maximum 17 mg/kg) 1
• Adenosine may be considered for diagnostic purposes in regular monomorphic wide-complex tachycardias 1

For Specific Tachycardia Types

• Sinus tachycardia: Identify and treat underlying cause (infection, dehydration, anemia, etc.) 1
• Inappropriate sinus tachycardia: Beta-blockers or ivabradine for symptom control 1
• Atrial fibrillation/flutter: Rate control with beta-blockers, calcium channel blockers, or digoxin 1
• AVNRT/AVRT: Acute termination with adenosine, long-term management with catheter ablation 1

Potential Complications and Monitoring

• Persistent tachycardia >120-130 bpm can lead to tachycardia-induced cardiomyopathy if sustained for days to weeks 2
• Elevated heart rates increase myocardial oxygen demand and can precipitate ischemia in patients with coronary artery disease 3
• Postoperative tachyarrhythmias often indicate underlying problems such as infection, hypotension, metabolic derangements, or hypoxia 1
• Monitor for electrolyte abnormalities (especially hypokalemia and hypomagnesemia) which can exacerbate tachyarrhythmias 1, 4

Follow-up Considerations

• All patients with significant tachyarrhythmias should be referred for heart rhythm specialist evaluation 5
• Long-term management depends on frequency of symptoms, risk stratification, and patient preference 5
• Catheter ablation is curative for many SVTs and should be considered for recurrent episodes 5
• Patients with resolved tachycardia-induced cardiomyopathy require careful long-term follow-up due to risk of recurrence 2