What are the immediate treatment steps for a patient with tachycardia, shortness of breath, and a heart rate of 127, who also experiences a feeling of stretching in the neck without chest pain?

Immediate Management of Tachycardia with Neck Pulsations

This patient's presentation of tachycardia (HR 127), shortness of breath, and neck stretching/pulsations without chest pain is highly suggestive of supraventricular tachycardia (SVT), most likely AVNRT, and should be treated immediately with vagal maneuvers followed by adenosine if unsuccessful. 1

Initial Assessment and Stabilization

• Place the patient supine immediately and assess hemodynamic stability by evaluating for hypotension, altered mental status, acute heart failure, or signs of shock 1
• Apply supplemental oxygen and monitor oxygen saturation, as hypoxemia is a common cause of tachycardia 1
• Establish IV access and attach continuous cardiac monitoring 1
• The neck pulsations ("stretching in the neck") are characteristic of SVT, specifically suggesting atrial contraction against a closed AV valve, which releases atrial natriuretic peptide 1

Determining Hemodynamic Stability

At HR 127 with preserved mental status and no chest pain, this patient appears hemodynamically stable 1. The 2010 AHA guidelines note that when heart rate is <150 bpm, symptoms are unlikely to be primarily caused by the tachycardia unless ventricular function is impaired 1. However, the shortness of breath warrants immediate intervention.

First-Line Treatment: Vagal Maneuvers

Initiate vagal maneuvers immediately as Class I recommendation 1:

• Valsalva maneuver: Have patient bear down against a closed glottis for 10-30 seconds, generating at least 30-40 mmHg intrathoracic pressure 1
• Carotid sinus massage: After confirming absence of carotid bruit by auscultation, apply steady pressure over the carotid sinus for 5-10 seconds 1
• Ice-cold towel to face: Apply ice-cold wet towel to trigger diving reflex 1
• Success rate is approximately 27.7% when switching between techniques 1

Second-Line Treatment: Adenosine

If vagal maneuvers fail, administer IV adenosine immediately (Class I recommendation) 1:

• Adenosine terminates AVNRT in approximately 95% of patients 1
• Serves both therapeutic and diagnostic purposes by unmasking atrial activity 1
• Critical caveat: Adenosine should be used with caution if severe coronary artery disease is present and may precipitate atrial fibrillation 1
• Avoid adenosine if patient has severe asthma 1

Third-Line Treatment: IV Calcium Channel Blockers or Beta-Blockers

If adenosine fails or is contraindicated, administer IV diltiazem or verapamil (Class IIa recommendation) 1:

• These agents are particularly effective for converting AVNRT to sinus rhythm 1
• IV beta-blockers are reasonable alternatives but less effective than diltiazem 1
• Critical warning: Do NOT use calcium channel blockers or beta-blockers if pre-excited atrial fibrillation is suspected, as this can cause hemodynamic collapse and ventricular fibrillation 1
• Avoid in patients with suspected systolic heart failure 1

If Medical Management Fails

Proceed to synchronized cardioversion if pharmacological therapy fails (Class I recommendation) 1:

• Synchronized cardioversion is highly effective for terminating SVT 1
• Administer sedation if patient is conscious 1
• Success rates of 80-98% are expected with pharmacological agents, making cardioversion rarely necessary in stable patients 1

Essential Diagnostic Steps During Treatment

• Obtain 12-lead ECG during tachycardia to confirm diagnosis, but do not delay treatment 1
• Record ECG during vagal maneuvers or drug administration, as the response aids diagnosis even if arrhythmia doesn't terminate 1
• If tachycardia terminates with a P wave after the last QRS, this favors AVRT or AVNRT 1

Critical Pitfalls to Avoid

• Do not assume sinus tachycardia without ECG confirmation—the neck pulsations strongly suggest SVT 1
• Never use IV calcium channel blockers and beta-blockers together due to potentiation of hypotensive and bradycardic effects 1
• Do not delay treatment to obtain extensive workup in symptomatic patients 1
• Avoid adenosine in severe asthmatics—use calcium channel blockers instead 1
• Do not use AV nodal blocking drugs if pre-excitation (WPW syndrome) is suspected on baseline ECG 2

Post-Conversion Management

• Monitor for recurrence after successful conversion 2
• Consider echocardiography to exclude structural heart disease if SVT is sustained 1
• Refer to cardiac electrophysiologist if episodes are recurrent, drug-resistant, or patient desires definitive therapy 1