What could be causing a sensation of feeling my heartbeat in my left ear while pregnant?

Pulsatile Tinnitus in Pregnancy

The sensation of hearing your heartbeat in your left ear during pregnancy is most likely pulsatile tinnitus caused by normal physiological changes—specifically increased blood volume, enhanced cardiac output, and bounding pulses that characterize normal pregnancy—and typically requires only reassurance unless accompanied by concerning symptoms.

Understanding the Physiological Basis

During normal pregnancy, your cardiovascular system undergoes dramatic changes that can create this sensation:

• Blood volume increases by approximately 40-50%, creating a hyperdynamic circulatory state with bounding pulses and widened pulse pressure 1
• Cardiac output rises significantly, with stroke volume increasing by 27-35% depending on gestational age, particularly when lying on your left side 1
• Heart rate increases by 10-20 beats per minute above baseline, contributing to the perception of pulsations 1
• Systemic vascular resistance falls, with disproportionately greater lowering of diastolic blood pressure, creating the characteristic wide pulse pressure and bounding quality 1

Physical Examination Findings in Normal Pregnancy

The physical examination of a normal pregnant woman characteristically reveals findings that explain pulsatile sensations:

• Bounding pulses and widened pulse pressure are expected findings 1
• Hyperkinetic precordial impulse with louder first heart sounds 1
• Continuous murmurs may be heard, including cervical venous hums (best in right supraclavicular fossa) and mammary souffles (over engorged breasts), both representing normal vascular flow sounds that can be obliterated with position changes or pressure 1

These normal findings can create audible pulsations, particularly when blood vessels near the ear are engorged or when lying in certain positions.

When to Seek Immediate Evaluation

While pulsatile tinnitus is usually benign in pregnancy, you should seek urgent medical attention if accompanied by 2, 3:

• Sudden onset dizziness or lightheadedness with the pulsations
• Documented rapid heart rate (pulse >120 bpm at rest)
• Chest discomfort, dyspnea, or severe fatigue
• Syncope or near-syncope episodes
• Abnormal blood pressure readings suggesting hemodynamic instability
• Severe or persistent headaches, particularly with visual changes

Positional Factors

The sensation may be more pronounced in certain positions due to:

• Inferior vena caval compression when lying supine, which can cause abrupt decreases in cardiac preload and compensatory changes 1
• Enhanced blood flow when lying on the left side, which is actually the optimal position for maternal-fetal circulation 1
• Cervical venous hums that are position-dependent and can be eliminated by turning your head or applying gentle pressure over the jugular vein 1

Recommended Management Approach

For isolated pulsatile tinnitus without concerning symptoms 2, 4:

1. Reassurance that this represents normal physiological changes of pregnancy
2. Lifestyle modifications: Avoid stimulants including excessive caffeine, as these can exacerbate the sensation 4
3. Positional adjustments: Experiment with head elevation during sleep and avoid positions that worsen symptoms
4. Hydration and adequate rest, as dehydration can worsen palpitations and related sensations 4

If symptoms are bothersome or associated with documented tachycardia, evaluation should include 2, 3:

• 12-lead ECG to assess for underlying arrhythmias or electrical abnormalities
• Continuous cardiac monitoring if palpitations are frequent
• Echocardiography to rule out structural heart disease or peripartum cardiomyopathy if clinically indicated 4, 3

Important Caveats

• Arrhythmias are more common in pregnancy, occurring in 10-60% of women with underlying heart conditions and up to 80% during pregnancy itself, due to hemodynamic, hormonal, and emotional changes 1
• Most palpitations in pregnancy are benign, typically caused by atrial or ventricular extrasystoles 4
• Peripartum cardiomyopathy can present late in pregnancy or postpartum with new symptoms, though this typically includes more than just pulsatile tinnitus 1, 3
• The postpartum period (first 4 weeks) carries particular risk for cardiac complications, so symptoms persisting or worsening after delivery warrant evaluation 1

Red Flags Requiring Cardiology Referral

Seek specialist evaluation if you have 1, 2:

• History of structural heart disease or congenital heart conditions
• Previous arrhythmias or family history of sudden cardiac death
• Thyroid disease, as hyperthyroidism can cause or exacerbate cardiac symptoms
• Persistent symptoms despite reassurance and lifestyle modifications
• Any hemodynamic instability or syncope with the pulsations

The key distinction is between normal physiological changes causing audible pulsations versus pathological tachyarrhythmias requiring intervention. In the absence of concerning associated symptoms, pulsatile tinnitus in pregnancy is typically a benign manifestation of the hyperdynamic circulation.