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“Low Voltage ECG” and Pericardial Effusion

1979; Elsevier BV; Volume: 75; Issue: 2 Linguagem: Inglês

10.1378/chest.75.2.113

1931-3543

David H. Spodick,

Cardiomyopathy and Myosin Studies

A nyone dealing with large numbers of electrocardiograms must be aware of the myriad of problems with voltage, both high and low. While progressive changes in voltage (in either direction) carry certain implications, every clinician is aware of frequently tantalizing day-to-day R-wave fluctuations. For example, in diagnosing left ventricular hypertrophy, the unreliability of isolated voltage criteria and short-term variability of R-wave voltage are notorious. Low voltage, although pluricausal and rather common in hospitalized populations, has been a comparatively neglected phenomenon. Unverferth and colleagues (see page 157) investigated the role of low voltage in the diagnosis of pericardial effusions, including the sensitivity and specificity of this electrocardiographic datum in the diagnosis of pericardial effusion. They have employed reasonable criteria for the interpretation, "low voltage," which might well be generally adopted. In 64 patients with pericardial fluid, echocardiographic estimation of the volumes of effusions was not quantitatively related to electrocardiographic voltage; after pericardiocentesis in 22 patients, frontal-plane and precordial voltages increased only slightly. The low specificity of a low-voltage ECG" was confirmed in 36 other patients with low voltage, among whom only 13 had pericardial effusion by echocardiographic findings. In discussing their findings, Unverferth et al ably dealt with the relationship of low voltage to pericardial effusion. Three other considerations bear on this relationship. First, a decrease in voltage is common in fluid-retention states of almost any pathogenesis, eg, cirrhosis of the liver, nephrotic syndrome, and congestive heart failure. Secondly, cardiac tamponade is not discussed in this report, although one might guess that this was a principal reason for pericardiocentesis. In tamponade, the decrease in voltage may be largely on the basis of the hemodynamic impairment itself, rather than simple accumulation of fluid.1Spodick DH Pathogenesis and clinical correlations of the elect***rocardiographic abnormalities of pericardial disease.in: Rios G Clinico-Electrocardiographic Correlations. FA Davis Co, Philadelphia1977: 201-214Google Scholar This was demonstrated by recording from endocardial sites, which could not be affected by the insulating effect of pericardial fluid.2Toney JC Kolmen SN Cardiac tamponade: Fluid and pressure effects on electrocardiographic changes.Proc Soc Exper Biol Med. 1966; 121: 642Crossref Scopus (5) Google Scholar Thus, patient-to-patient variability in the degree of cardiac compression could have confounded the relation of the volume of effusion to voltage. Thirdly, spurious change in voltage may result (although probably not of great magnitude) from a shift of the QRS axis after pericardiocentesis.3Spodick DH Acute cardiac tamponade: Pathophysiology, diagnosis and management.Prog Cardiovas Dis. 1967; 10: 64-96Abstract Full Text PDF PubMed Scopus (82) Google Scholar The foregoing considerations serve to supplement a successful effort to deal with the important general problem of low voltage and the specific problem of pericardial effusion. Unverferth et al have ably performed a much needed study and have employed a quantitative approach to what previously could only have been inchoate clinical impressions.