ECG criteria
- ST elevation ≥ 1 mm in V4R (J point, measured relative to the TP segment, or PR if the TP is indistinguishable) is the most sensitive and specific sign
- The same applies to V3R–V6R, but V4R provides the best balance of sensitivity and specificity
- ST elevation in V1 in the setting of inferior MI (the only standard chest lead facing the right ventricle)
- The magnitude of ST elevation in V1 is greater than in V2 (in isolated inferior MI without RV involvement, the reverse is usually true: depression or smaller elevation in V1)
- ST elevation in V4R often resolves rapidly, especially after reperfusion, so right-sided leads should be recorded as early as possible from symptom onset; a negative result, especially later on, does not rule out RV infarction
- Associated signs of inferior STEMI: ST elevation in II, III, aVF with reciprocal depression in I, aVL
- Classic clinical triad of RV infarction: hypotension, elevated jugular venous pressure, and clear lung fields with an intact left ventricle; Kussmaul's sign (paradoxical rise in jugular venous pressure during inspiration) may be present
What it looks like on ECG
Standard 12-lead ECGs do not include a lead directly facing the right ventricle (except partially V1). Therefore, in any inferior STEMI (ST elevation in II, III, aVF), additional right-sided chest leads should be recorded: V3R, V4R, V5R, V6R — with electrodes placed symmetrically to the left chest leads, but on the right hemithorax.
| Lead | Position |
|---|---|
| V2R | 4th intercostal space at the right sternal border |
| V3R | midway between V2R and V4R |
| V4R | 5th intercostal space at the right midclavicular line |
| V5R | 5th intercostal space at the right anterior axillary line |
| V6R | 5th intercostal space at the right midaxillary line |
V4R, V5R, and V6R are placed as mirror images of the corresponding left chest leads.
ST-segment elevation ≥ 1 mm in V4R (J point, measured relative to the TP segment, or PR if the TP is indistinguishable; at a standard calibration of 10 mm/mV, 1 mm vertically corresponds to 0.1 mV, with a standard paper speed usually of 25 mm/s) is a key diagnostic criterion. This sign is most sensitive and specific in the first hours of infarction: ST elevation in V4R often regresses rapidly, especially after reperfusion, so right-sided leads should be recorded as early as possible after symptom onset. A negative ECG in right-sided leads, particularly when recorded later, does not rule out prior RV infarction — the diagnosis is additionally assessed based on clinical presentation, hemodynamics, echocardiography, and coronary angiography findings.
In standard leads, RV infarction is suspected indirectly if, in the setting of inferior STEMI, ST elevation in V1 is more pronounced than in V2, or if there is ST elevation in V1 while it is absent or minimal in V2–V3.
Mechanism
In most cases, the right ventricle is supplied by branches of the right coronary artery (RCA): right ventricular branches originating proximally, prior to the acute marginal branch. Occlusion of the RCA proximal to these branches causes ischemia and necrosis not only of the inferior wall of the left ventricle, but also of the free wall of the right ventricle. The right ventricle operates under low pressure in the pulmonary circulation and often tolerates acute ischemia better than the left ventricle; upon restoration of blood flow, stunned myocardium and RV dysfunction frequently recover partially or substantially, and faster than analogous LV injury. An additional factor may be variable collateral circulation, but it is not an obligatory feature of the RV.
Causes
- Proximal right coronary artery occlusion (prior to the right ventricular branches) is the primary cause
- Less commonly, occlusion of a dominant circumflex artery in left coronary dominance
- Accompanies inferior or inferoposterior myocardial infarction; isolated RV infarction without involvement of the inferior LV wall is rare
Differential diagnosis
- Isolated inferior MI without RV involvement — no ST elevation in V4R, hemodynamics are more stable
- PE with acute right heart strain — ECG is nonspecific: typically signs of RV strain (tachycardia, SI-QIII-TIII pattern, RBBB, T-wave inversions in V1–V4); infarction-type ST elevation in right-sided chest leads is uncharacteristic, though nonspecific ST changes may occasionally occur; the diagnosis of PE is established via clinical presentation and diagnostic algorithms rather than ECG findings alone
- Pericarditis — diffuse concordant ST elevation without reciprocal depression and without an isolated pattern in right-sided leads
- Right ventricular hypertrophy with strain — chronic, stable ST-T changes in V1–V3 without acute dynamics
Clinical significance and management
RV infarction changes management in inferior STEMI. The right ventricle relies predominantly on preload, so a decrease in venous return can lead to a drop in cardiac output and arterial hypotension. The clinician should:
- in the presence of hypotension or a hemodynamically significant RV infarction, avoid nitrates and other preload-reducing agents; avoid diuretics in preload-dependent states and hypovolemia
- monitor blood pressure and signs of congestion, and cautiously administer fluid therapy guided by hemodynamic parameters when necessary, rather than routine volume loading
- promptly consider cardiac pacing in the presence of bradycardia and AV block (a frequent association with proximal RCA occlusion)
- perform primary PCI within standard timelines for STEMI, specifically restoring blood flow in the RCA
RV infarction is associated with higher in-hospital mortality in inferior STEMI, but with effective reperfusion, RV function often recovers more completely than LV function in anterior infarction.
Common interpretation errors
- Failing to record right-sided leads in inferior STEMI, even though it should be routine
- Recording V4R too late, when ST elevation has already resolved, and mistakenly ruling out RV involvement
- Administering nitrates in inferior STEMI with hypotension without considering potential RV infarction
- Confusing changes in V1 during RV infarction with signs of anteroseptal infarction
- Failing to recognize concurrent AV block as a sign of proximal RCA occlusion with RV involvement
1. Which ECG criterion is most specific for right ventricular infarction?
ST-segment elevation ≥ 1 mm in the right chest lead V4R is the key and most specific sign of right ventricular infarction.
2. Which coronary artery most frequently causes right ventricular infarction?
Right ventricular branches arise proximally from the right coronary artery, so its occlusion prior to these branches causes RV ischemia along with the inferior wall of the LV.
3. What is the appropriate approach regarding nitroglycerin in right ventricular infarction with hypotension?
In hypotension or hemodynamically significant RV infarction, nitroglycerin decreases preload, which is critically important for cardiac output, and may provoke a drastic worsening of hypotension.
Frequently asked questions
When to record V4R during an ECG?
In any inferior STEMI (ST elevation in II, III, aVF) — immediately upon detection, before the ST segment returns to the baseline. The earlier the ECG is recorded from symptom onset, the higher the chance of observing ST elevation in V4R.
Why should one be cautious with nitrates in right ventricular myocardial infarction?
During infarction, the right ventricle often relies on preserved preload. Nitrates dilate veins and reduce venous return, which can sharply decrease cardiac output and cause severe hypotension up to shock — therefore, they are not used in hypotension or hemodynamically significant RV infarction.
Is right ventricular myocardial infarction dangerous?
Yes, it increases the risk of hypotension, cardiogenic shock, and AV block in inferior STEMI and is associated with higher in-hospital mortality. At the same time, RV function often recovers better than LV function following successful reperfusion.
How to distinguish right ventricular myocardial infarction from PE on ECG?
In RV infarction, there is a direct ST-segment elevation in the right chest leads (V4R) against the background of an inferior STEMI. In PE, the ECG is non-specific: signs of acute right heart overload are more commonly detected — the S1Q3T3 pattern, new right bundle branch block, negative T waves in V1–V4 — and the diagnosis is established based on the clinical picture and PE diagnostic algorithm rather than a single ECG pattern.
Can right ventricular myocardial infarction be suspected without right-sided leads?
Indirectly — yes, if in an inferior STEMI the ST-segment elevation in V1 is more pronounced than in V2, or if ST elevation is present in V1 while absent in V2–V3. However, an accurate diagnosis requires recording V3R–V6R.
ECG Course
Interpretation from basics to myocardial infarction — learn to read any ECG using a systematic algorithm.
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Related terms
More in the section "Ischemia and Myocardial Infarction"
Sources
- Goldberger's Clinical Electrocardiography, 9th ed.
- Surawicz B., Knilans T. Chou's Electrocardiography in Clinical Practice, 6th ed.
- ESC Guidelines for the management of acute coronary syndromes in patients presenting with ST-segment elevation (ESC 2023)
- Orlov V.N. Guide to Electrocardiography
Educational material for medical students and physicians. Does not replace clinical guidelines and physical examination; the ECG must always be interpreted in conjunction with the clinical picture.