Poor R Wave Progression
Poor R wave progression is a common EKG pattern in which the expected increase of R wave amplitude in precordial leads does not occur 1.
In a normal EKG, the R wave progressively increases in amplitude from lead V1 toward leads V5 and V6, and the S wave decreases from the right toward the left precordial leads 2.
At some point, generally around the V3 or V4 position, the QRS complex changes from predominately negative to predominately positive.
It is important to note that poor R wave progression is a non-specific finding on an EKG and requires clinical correlation to determine the underlying cause. A detailed medical history, physical examination, and further diagnostic testing may be required to establish a diagnosis.
The situations in which poor R wave progression may be seen are as follows:
Causes of Poor R Wave Progression
Poor R wave progression may be found in approximately 7% of in asymptomatic subjects with no disease and proper electrode application, and was unrelated to patient morphology 3 4.
However, poor R wave progression may be a marker of unrecognized structural or electrical abnormalities and should prompt further evaluation 3.
Poor R wave progression in newborn and infant
Term newborn infants usually demonstrate right ventricular preponderance with prominent R waves in the right precordial leads and deep S waves in the left lateral precordial leads 2 5.
The amplitude of R waves in the right precordial leads of normal children decreases with age while the amplitude increases in the left precordial leads 6.
Similar but inverse changes occur in respect of the S wave amplitude. There is substantial individual variation in the rate at which these changes occur 6.
The absence of R waves in leads V1, V2, and even V3 or V4 in persons without heart disease is often caused by relatively high placement of electrodes in relation to the heart 2.
This means that when the diaphragm position is low, even the correctly placed precordial electrodes may face not the ventricles but the atria or the great vessels 2.
V1 and V3 Leads Reversal
This is one of the more common errors involving lead placement. This erroneous switching produces an EKG pattern in which the normal R and S wave progressions in the precordial leads V1 to V3 is lost.
It may be recognized by biphasic P waves in lead V3, while R waves in leads V1 and V2 are upright 2.
Anterior Wall Myocardial Infarction
A significant portion of patients with previous anterior wall myocardial infarction will masquerade merely having as poor R wave progression on surface EKG 4.
On the other hand, only 20% of patients with poor R wave progression have anterior myocardial infarction 1.
R waves are significantly lower in all precordial leads in patients with prior anterior myocardial infarction than those without 7.
In patients with prior anterior myocardial infarction, poor R wave progression usually reflects large myocardial infarct size and severely impaired left ventricular systolic function 7.
Left ventricular hypertrophy
Related article: Left ventricular hypertrophy.
Poor progression of the R wave in precordial leads occurs commonly with left ventricular hypertrophy and is associated with a leftward shift of the transitional zone in the precordial leads 2.
In left ventricular hypertrophy, the electrical activity is redirected due to the thickening of the left ventricular wall, which can lead to a lack of normal progression of the R wave from the right precordial leads to the left precordial leads.
Occasionally, R waves are absent in leads V1, V2, and even V3, resulting in a QS deflection in these leads that mimics anteroseptal myocardial infarction 2.
More information: Left ventricular hypertrophy.
Right ventricular hypertrophy
Related article: Right ventricular hypertrophy.
In right ventricular hypertrophy, there is an increase in the size and thickness of the right ventricle, which can lead to a shift in the electrical axis of the heart towards the right side. This can result in a lack of normal progression of the R wave from the right precordial leads to the left precordial leads.
Electrocardiographic manifestations of right ventricular hypertrophy includes right axis deviation, tall R waves in the right precordial leads (V1 and V2), deep S waves in the left precordial leads (V5 and V6), and a slight increase in QRS complex duration 2.
More information: Right ventricular hypertrophy.
A left-sided pneumothorax may cause poor R wave progression in precordial leads due to rotation of the heart by intrathoracic air. This situation may mimic an anterior wall myocardial infarction 8.
The electrocardiographic abnormalities described in left pneumothorax include poor R wave progression, T wave inversion in precordial leas, phasic QRS voltage variation. QRS voltage ratio (aVF/DI) greater than 2 has high sensitivity and specificity 9.
Electrocardiographic changes are secondary to several factors including clockwise rotation axis of the heart, dilated right ventricle, posterior displacement of the mediastinum, hypoxemia, and decreased coronary blood flow 9.
Electrocardiographic findings immediately improved after simple aspiration 8.
The most common EKG finding of pericardial effusion with or without cardiac tamponade is low voltage QRS complexes 10. Poor R progression in precordial leads can also be observed.
The presence of low voltage and sinus tachycardia should always raise concern about pericardial effusion with tamponade 10.
Another EKG finding that can occur with pericardial effusion and cardiac tamponade is electrical alternans. Electrical alternans with sinus tachycardia is a highly specific electrocardiographic sign of cardiac tamponade, but its absence does not exclude pericardial tamponade 10.
Poor R wave progression in precordial leads caused by emphysema are related to anatomic changes in heart position 11.
In emphysema, a significantly higher R/S ratio is observed in leads V1-V4, whereas in anterior myocardial infarction this higher ratio is observed in leads V5-V6 11.
Poor R wave progression with QS complexes in precordial leads V1-V4 (“pseudo-infarction” pattern) is a common finding in patients with dilated cardiomyopathy.
Low QRS voltages in peripheral and precordial leads have also been described, being the electrocardiographic expression loss of vital myocardium and its replacement by fibrotic tissue 12.
Congenital heart disease
While the specific mechanisms can vary depending on the type and severity of the defect, congenital heart diseases may sometimes be associated with poor R-wave progression on an EKG.
One possible reason for poor R wave progression in congenital heart diseases is the abnormal orientation of the electrical activity caused by the structural defects. The altered position and size of the heart chambers can affect the normal progression of the R wave on the precordial leads.
Furthermore, certain types of congenital heart diseases, such as right ventricular outflow tract obstruction or pulmonary hypertension, may lead to right ventricular hypertrophy. Right ventricular hypertrophy can also contribute to poor R wave progression.
Other Causes of Poor R Wave Progression
Left bundle branch block and Wolff-Parkinson-White syndrome, are characterized by recognizable intraventricular conduction patterns, in both cases, poor R wave progression in precordial leads can be observed 2.
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