Europace Advance Access originally published online on November 14, 2007
Europace 2008 10(1):96-98; doi:10.1093/europace/eum246
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ELECTROCARDIOGRAPHY
Precordial low voltage in patients with ascites
Department of Cardiology, Kantonsspital Luzern, 6000 Luzern 16, Switzerland
Manuscript submitted 1 August 2007. Accepted after revision 16 October 2007.
* Corresponding author. Tel: +41 412055106; fax: +41 412052234. E-mail address: paul.erne{at}ksl.ch
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Abstract |
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Aims: Electrocardiographic (ECG) changes in patients with ascites are not well studied. The aim of this study was to evaluate ECG changes in patients with ascites.
Methods and results: Prospective analysis of patients with ascites who were referred for paracentesis. Three ECGs were recorded before paracentesis. ECG 1 was a standard 12-lead ECG. For ECG 2 the precordial leads were placed 1 intercostal space (ICS) and for ECG 3, 2 ICS cranially. The sums (
) of the QRS in ECG1 were compared with ECG 2 and 3. In six patients the same ECG protocol was performed after removal of ascites. Ten hospitalized patients without ascites served as controls. Twenty patients with ascites were analysed. Limbs leads low voltage was present in 11 patients and precordial low voltage in four patients. Cranial placement of the precordial electrodes increased QRS in all patients with ascites. The most prominent voltage changes appeared in the leads V4–V6 (+62%). Paracentesis of ascites normalized precordial leads low-voltage, while limbs leads low voltage remained. Cranial placement of the precordial electrodes in patients without ascites decreases V1–V6.
Conclusion: We describe a phenomenon of precordial voltage changes in patients with ascites, not reported in the literature yet. By placing the precordial electrodes 1 and 2 ICS cranially the voltage changes can be ‘corrected’ and this should be done in all patients prior to further diagnostic workup. Removal of the ascites normalizes the precordial leads low voltage.
Key Words: Ascites, ECG, Precordial low voltage, Intercostal space
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Introduction |
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Low voltage on the surface electrocardiogram (ECG) is defined as a QRS amplitude <10 mm in the precordial and <5 mm in all limbs leads.1
Limbs leads low voltage is not uncommon in clinical practice and its differential diagnosis includes conditions such as obesity, lung emphysema, pericardial effusion, hypothyroidism and amyloidosis. Low voltage of the precordial leads is less common than limbs leads voltage and might be a feature of cardiac tamponade2 or appear temporarily after defibrillation or cardioversion.3
Little is known about the prevalence of low voltage in patients with ascites. Recently, Madias4 described two patients with liver cirrhosis, ascites, and peripheral oedema, who presented with low voltage. The low voltage phenomenon was accounted to peripheral oedema and not to ascites in these patients.
To our knowledge, an association of low voltage of the precordial leads with ascites has not been described before. Ascites leads to an increase in intra-abdominal pressure and has a negative impact on cardiac haemodynamics and renal function.5,6
Since an increase in intra-abdominal pressure has effects on intrathoracic pressure,7 we hypothesized that ascites influences the anatomical position of the heart and thus the electrical axis of the heart.
The aim of this prospective study was to evaluate ECG changes in the precordial leads of patients with ascites.
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Patients and methods |
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Between March and September 2007 we recorded ECGs of patients with ascites who were referred for paracentesis. In those patients with low voltage, an echocardiography was performed to exclude pericardial effusion.
ECG
The ECGs were recorded before paracentesis by a Schiller CS 100 ECG recorder. In each patient, a total of three 12-lead ECGs were performed. The first ECG was a 12-lead standard ECG. The limbs leads were placed on the extremities for all three recordings. For the second ECG the six precordial electrodes were moved 1 intercostal space (ICS) cranially and for the third ECG these electrodes were moved 2 ICS cranially compared with standard recording. In eight patients with ascites, the ECG recordings were performed after ascites was removed as mentioned above.
Ten hospitalized patients without ascites served as controls and underwent the same protocol of ECG recordings.
The sum () of the QRS amplitudes was created in all patients for the leads V1–V3 and V4–V6. The sums at baseline (ECG 1) were then compared with the sums of ECG 2 and 3. The increase in voltage was calculated as percentage (%).
In eight patients voltage change after paracentesis of ascites is reported.
In patients with low voltage criteria (QRS amplitude < 10 mm in all precordial and <5mm in all limbs leads1), echocardiography was performed and pericardial effusion was excluded in all cases.
Statistical analysis
Age is reported median, while the minimum and maximal values are given in brackets. The increase in voltage compared with baseline is reported as percentage (%). STATVIEW software from the SAS Institute (www.statview.com) was used for statistical analysis. For comparison of voltage increase between the different nominal groups an unpaired t-test was used. A P-value <0.05 was used as significance level.
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Results |
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Patient characteristics
We included a total of 20 consecutive patients (seven females) with a median age of 62 years (range: 40–85 years). The aetiology of the ascites was accounted to a malignant process in 10 patients. In the other 10 patients ascites was due to alcoholic liver cirrhosis. Lung emphysema was present in six patients. Limbs oedemas were present in all patients. The control group (n = 10, three females) had a median age of 61 years.
Electrocardiographic effects of ascites
The mean sum of the QRS amplitude for the leads V1–V3 was lower in patients with ascites compared with the control group (27.3 ± 9.1 vs. 44.6 ± 11.9 mm, P < 0.002). The sum of the QRS amplitudes was also lower in patients with ascites when the leads V4–V6 were analysed (18.0 ± 8.5 vs. 55.0 ± 21.5 mm, P < 0.0001).
Limbs leads low voltage was present in 11 patients (54%) and precordial low voltage in four patients (36%) with ascites. The median QRS axis was 35°.
Effects of upward shift of the precordial electrodes on the QRS voltage
The mean QRS for V1–V3 was 27.3 ± 9.1 mm at baseline. When the electrodes were shifted 1 ICS cranially the sum increased to 30.7 ± 7.9 (P = 0.042). The mean QRS for the leads V4–V6 was 18.0 ± 8.5 at baseline and it increased to 24.4 + 7.9 after shifting the electrodes 1 ICS cranially (P = 0.0002).
Comparison of increments of the QRS amplitude (in %) when moving the precordial electrodes 1 and 2 ICS cranially is presented in Figure 1 for all patients. The largest increase (+62%) of QRS is achieved when the electrodes V4, V5, and V6 are placed 2 ICS cranially. Voltage changes of patients from the control group (without ascites) when precordial leads are placed 1 and 2 ICS cranially are shown on the right side of Figure 1. Cranial placement of the electrodes leads to a decrease in QRS (–21% for QRS V4–V6 when the electrodes are placed 2 ICS cranially).
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No significant difference was observed between patients with or without emphysema (+56 vs.+64%, P = 0.88 for
QRS when V4–V6 electrodes are placed 2 ICS cranially).
Effects of fluid evacuation on the electrocardiogram
A median of 6200 mL ascites was removed (range 3000–6000 mL). Compared with the initial standard ECG, QRS increased 98% for V1–V3 and 134% for QRS of V4–V6. Paracentesis of ascites corrected precordial low voltage in all patients.
QRS for the limbs leads was similar before and after ascites paracentesis (26.8 vs. 27.0 mm, P = 0.94). The median QRS axis was 50° after evacuation of ascites.
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Discussion |
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TopAbstractIntroductionPatients and methodsResultsDiscussionReferences |
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We describe a phenomenon of pseudo voltage-loss in the precordial leads in patients with ascites of malignant and non-malignant aetiology. Four patients had precordial low voltage, defined as QRS amplitude <10 mm in all precordial leads. Removal of ascites corrects low voltage in these patients. To our knowledge, precordial low voltage has not been related to ascites so far.
Many studies on QRS amplitude have been performed in patients with other conditions that present with oedema and/or volume overload.4,8–13 Changes had been mostly attributed to the effect of generalized fluid retention and not to ascites. Recently, Madias4 described two patients with liver cirrhosis, ascites, and peripheral oedema, who had low voltage in the limbs leads. The low voltage phenomenon was accounted to peripheral oedema and not to ascites in these patients. In our series, all patients had limbs oedema but only 11 subjects had limbs low voltage.
We believe that the reason for the low voltage in the precordial leads is a shift of the anatomical heart axis in response to the abdominal pressure. Because the ECG is recorded in the supine position, the abdominal pressure causes a cranial movement of the diaphragm and thus cranial shift of the heart apex. To prove this hypothesis, we recorded two additional ECGs moving the precordial leads 1 and 2 ICS cranially, with a more prominent increase in leads V4, V5, and V6 which indicates that this is due to a change in the anatomical axis. The fact that the voltage returns to normal value after ascites has been removed supports our hypothesis. Figure 2A shows an impressing example of a patient with ascites and precordial low voltage. In Figure 2B (recorded just 1 min later), by moving the precordial electrodes 2 ICS cranially, QRS voltage markedly improves. In Figure 2C the ECG after ascites removal is presented. The amplitude has dramatically improved compared with the ECG in Figure 2A.
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Patients without emphysema had higher increases in QRS voltage when the precordial electrodes were placed 2 ICS higher but the difference was not significant. The reason that patients with emphysema have less increase in voltage is probably related to the over inflated lungs and flat diaphragm in these patients. Because the motion of the diaphragm is limited in patients with emphysema,14
higher intra-abdominal pressure is needed to move the diaphragm (and thus the heart apex) cranially.
Clinical implications
We believe that for the care of patients suffering from ascites the knowledge of this phenomenon is of relevance. In patients with ascites, precordial low voltage could suggest a cardiac pathology (i.e. pericardial effusion, pericardial tamponade or chronic coronary artery disease). While limbs leads low voltage could be associated to limbs oedema, low voltage of the precordial leads is related to ascites and can be corrected if the leads are placed 1 or 2 ICS cranially or the ECG is recorded after ascites has been removed. The fact that voltage returns to normal on a standard ECG after ascites is removed, confirms our hypothesis.
Conflict of interest: none declared.
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References |
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[1] Eisenberg MJ, de Romeral LM, Heidenreich PA, Schiller NB, Evans GT Jr. The diagnosis of pericardial effusion and cardiac tamponade by 12-lead ECG. A technology assessment. Chest (1996) 110:318–24.[Web of Science][Medline]
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