What causes fluttering and pulsating sensations in the right upper quadrant (RUQ) and right sternal border after consuming multiple sodas?

Fluttering and Pulsating Sensations in RUQ After Soda Consumption

The fluttering and pulsating sensations you're experiencing in the right upper quadrant and right sternal border after drinking multiple sodas are most likely benign palpitations triggered by carbonation-induced gastric distension, caffeine stimulation, or sugar/artificial sweetener effects on cardiac rhythm, though cardiac arrhythmias—particularly atrial flutter or supraventricular tachycardia—must be excluded with an ECG if symptoms are frequent, prolonged, or associated with lightheadedness.

Primary Differential Diagnosis

Benign Gastrointestinal Causes (Most Likely)

• Gastric distension from carbonation can cause palpable pulsations in the RUQ that patients perceive as cardiac in origin, particularly when the distended stomach pushes against the diaphragm and creates awareness of normal cardiac activity 1
• Gastroesophageal reflux symptoms are significantly associated with soda consumption, with a 29% increased risk when consuming more than 6 servings daily compared to none (HR 1.29,95% CI 1.05-1.58), and these symptoms can manifest as chest discomfort in the right sternal border region 2
• The carbonation and volume load can create mechanical pressure effects that make normal cardiac pulsations more perceptible in the epigastric and RUQ regions 1

Cardiac Arrhythmia Triggers (Must Exclude)

• Atrial flutter is significantly associated with alcohol intake in younger patients (OR 17 in patients ≤60 years), and the mechanism involves shortening of right atrial effective refractory periods 3
• While the evidence specifically addresses alcohol, caffeine and sugar in sodas can trigger similar supraventricular arrhythmias through catecholamine release and autonomic stimulation 1
• Supraventricular tachycardia (SVT) characteristically presents with abrupt onset palpitations that patients describe as "fluttering" sensations, with rates typically 150-250 bpm 1

Metabolic and Hemodynamic Effects

• Hypertension risk increases by 12% with sugar-sweetened soda consumption (pooled RR 1.12,95% CI 1.03-1.23) and by 15% with artificially sweetened soda (pooled RR 1.15,95% CI 1.11-1.19), which can increase awareness of cardiac pulsations 4
• Large volume intake causes acute volume expansion that may transiently increase cardiac output and make pulsations more noticeable 4

Immediate Clinical Assessment Required

Red Flag Symptoms Requiring Urgent ECG

• Sustained palpitations lasting >30 seconds suggest true arrhythmia rather than benign awareness of normal rhythm 1
• Associated lightheadedness, presyncope, or syncope indicates hemodynamically significant arrhythmia requiring immediate evaluation 1
• Chest pain or dyspnea accompanying the fluttering sensation warrants urgent cardiac assessment 1
• Grossly irregular rhythm (if you can palpate your pulse during symptoms) suggests atrial fibrillation or multifocal atrial tachycardia 1

Physical Examination Priorities

• Palpate the RUQ during symptoms to determine if the sensation corresponds to visible epigastric pulsations (suggests gastric distension or transmitted aortic pulsation) versus true cardiac arrhythmia 1
• Check pulse rate and regularity during symptomatic episodes—a regular tachycardia at exactly 150 bpm suggests atrial flutter with 2:1 conduction 1
• Assess for hepatomegaly or pulsatile liver which could indicate right heart pathology, though this is unlikely in your presentation 1

Diagnostic Algorithm

Step 1: Obtain 12-Lead ECG

• Baseline ECG is mandatory if symptoms are recurrent, even if you're currently asymptomatic, to assess for pre-excitation patterns, baseline QTc prolongation, or other substrate for arrhythmia 1
• ECG during symptoms is diagnostic—capture rhythm during next episode using smartphone-based ECG device or emergency department visit 1

Step 2: Temporal Association Testing

• Eliminate soda consumption for 2 weeks and document whether symptoms completely resolve—this strongly suggests benign trigger rather than underlying cardiac pathology 2
• Substitution analysis: Replace soda with water, as this reduces GER symptoms by 8% (HR 0.92,95% CI 0.89-0.96) and may eliminate trigger if gastric distension is the cause 2

Step 3: Risk Stratification

• Age <60 years with daily alcohol or caffeine intake increases atrial flutter risk significantly (OR 17), warranting lower threshold for extended cardiac monitoring 3
• Family history of sudden cardiac death or known arrhythmias requires cardiology referral regardless of ECG findings 1

Management Recommendations

Immediate Lifestyle Modifications

• Complete elimination of carbonated beverages for minimum 2-week trial period to assess symptom resolution 2
• Avoid large-volume fluid intake in single sitting, as gastric distension is the likely culprit if symptoms are truly positional and related to meals 2
• Limit caffeine intake from all sources (coffee, tea, energy drinks) as caffeine can trigger supraventricular arrhythmias through catecholamine release 1

When to Pursue Cardiac Workup

• Symptoms persist despite soda elimination for 2 weeks—proceed to 24-48 hour Holter monitor or 30-day event monitor 1
• Any documented tachycardia >100 bpm at rest on pulse check during symptoms warrants cardiology evaluation 1
• Symptoms occur with exertion or are associated with presyncope—these are high-risk features requiring stress testing and echocardiography 1

Common Pitfalls to Avoid

Don't Dismiss as "Just Anxiety"

• While benign palpitations are common, atrial flutter with 2:1 conduction presents with ventricular rate of exactly 150 bpm and can be mistaken for anxiety-related sinus tachycardia 1
• Paroxysmal SVT characteristically has abrupt onset/termination that patients clearly distinguish from gradual anxiety-related tachycardia 1

Don't Overlook Electrolyte Effects

• Hypokalemia and hypomagnesemia from chronic diuretic effect of caffeine can predispose to arrhythmias and should be checked if symptoms persist 1
• Large sugar loads can cause reactive hypoglycemia 2-3 hours post-consumption, triggering catecholamine surge and palpitations 1

Don't Ignore Positional Components

• If symptoms are worse when lying down or bending forward, this strongly suggests gastroesophageal or gastric distension mechanism rather than primary cardiac pathology 2
• Relief with belching or passing gas is pathognomonic for gastric distension as the cause 1