International Archives of

Int Arch Occup Environ Health 43, 167-175 (1979)

Oeupalnal

and Eilnmenta Health © Springer-Verlag 1979

Electrocardiographic Signs of Cor Pulmonale in Asbestosis K Kokkola and M S Huuskonen Laakso Hospital and Institute of Occupational Health, Haartmaninkatu 1, SF-00290 Helsinki 29, Finland

Summary A cross-sectional study examining the prevalence of electrocardiographic (ECG) signs of cor pulmonale and their correlation with ventilatory capacity was carried out with 130 asbestosis patients and 121 referents The ventilatory function of 120 of the 130 patients was measured, 41 having a normal FEVI o, 50 slight FEV O o impairment and 29 moderate or severe FEV Oo impairment The cor pulmonale signs were more prevalent in the asbestosis than in the reference group, the greatest differences being found in PII,III,aVF amplitude, PV, amplitude, AQRS deviation to the right and'shift of QRS transition to the left These differences were not, however, statistically significant The frequencies of electrocardiographic cor pulmonale findings in the three FEV Oo categories of asbestosis patients were established The atrial parameters P, II 1,a VF ' AP, and PV correlated the best with FEVo0 , but only the relationship PVI/FEV Oo was significant (P 80% of predicted), 50 (41 7%) had a slight FEV, o impairment (60-79 % of predicted) and 29 (24 1%) had a moderate or severe FEV, o impairment (< 60% of predicted) Thirteen of the 120 patients (10 8%) revealed obstruction, defined as a delta FEV% (predicted minus observed) of at least 13 %. Radiographs were classified according to ILO's classification (1972) Of the patients 64 (49 %) were found to have radiographically mild diffuse pulmonary fibrosis (profusion 0/1, 1/0 or 1/1), 47 (36%) moderate fibrosis (1/2, 2/1 or 2/2) and 19 (15%) diffuse fibrosis in an advanced stage (2/3 or more) The type of fibrosis was mostly irregular (107 = 82%). A matched referent (by sex and year of birth) was available for 121 asbestosis patients The physical characteristics of those asbestosis patients with a referent and the reference group are shown in Table 1.

Methods Electrocardiography The ECG's were made with a Mingograph 34-apparatus (Elema-Sch 6 nander, Sweden) The 12lead ECG's were taken with the subjects supine at rest; the recording speed was 50 mm/s. The analyses of ECG parameters were based on the so-called Minnesota Code (Blackburn et al , 1960; International Society of Cardiology, 1964; Rose and Blackburn, 1968), which was

Electrocardiographic Signs of Cor Pulmonale in Asbestosis

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169

170

K Kokkola and M S Huuskonen

supplemented with some ECG variables illustrating a cor pulmonale pattern The items analysed were the following: 1 Q or QS pattern (Minnesota Code 11,2,3) 2 High amplitude left R wave (Minnesota Code III,3) 3 S-T segment depression (Minnesota Code IV1,2,3) 4 Negative or isoelectric T wave (Minnesota Code V 2,3, only in leads I, II, a VL and V6) 5 A-V conduction defects (Minnesota Code VII-5 ) 6 Ventricular conduction defects (Minnesota Code VII- 6) 7 Disturbances of the basic rhythm (Minnesota Code VIII 2- 6) 8 AQRS (Minnesota Code II) 9 High amplitude right R wave (Minnesota Code 112) 10 P wave amplitude , 2 5 mm in any of leads II, III, aVF (Minnesota Code IX 3) 11 AP, according to the same classification as in AQRS 12 PV, (positive deflection) 1 mm 13 Premature beats, according to the Scandinavian Modification of the Minnesota Code (The Scandinavian Committee on ECG Classification 1967) 14 QRS transition zone: a) at V1 or between VI and V 2; b) at V2 or between V2 and V3 etc , six classes 15 R wave amplitude in leads V5 or V6 (minimum): a) >8 mm, b) 8 5mm, c) 80%

60-79 %

< 60 %

Numbera

Per cent

Numbera

Per cent

Numbera

Per cent

37/41 3/41 1/41

90 7 2

44/50 4/50 2/50

88 8 4

26/29 3/29 0/29

90 10 0

38/41 2/41 1/41

93 5 2

44/50 5/50 1/50

88 10 2

24/29 5/29 0/29

83 17 0

> 8 mm

24/41 14/41 3/41

59 34 7

42/50 7/50 1/50

84 14 2

18/29 10/29 1/29

62 34 3

Transition VI, or between V 1 and V2 V 2, or between V2 and V 3 V3, or between V3 and V4 V4,or between V4 and V5 Vs, or between Vs and V6 V6,or beyond

4/41 8/41 25/41 3/41 0/41 1/41

10 20 61 7 0 2

2/50 10/50 31/50 6/50 1/50 0/50

4 20 62 12 2 0

1/29 5/29 17/29 5/29 1/29 0/29

3 17 59 17 3 0

Terminal notching of the QRS Notching absent Notching present

33/41 8/41

80 20

44/50 6/50

88 12

28/29 1/29

97 3

AQRS -90 °

+890

+90-+

119 °

+120 °

150 °

RV 5 ,6 > 8 mm

8-5 mm < 5mm SV 5 ,6 < 5mm 5-8 mm

a

Number of findings / total number of observations

Electrocardiographic Signs of Cor Pulmonale in Asbestosis

173

The distributions of the ECG variables consistent with right ventricular overload are shown in Table 4 according to the ventilatory capacity categories of the asbestosis group AQRS deviation to the right (+90° or beyond) was infrequent in all three subgroups A large SV5,6 amplitude ( 5 mm) was quite common in the series (36 out of 120), but there were no differences between the subjects with normal and reduced ventilatory capacity The shift of the transition zone to V4 or further and the small RVs,6 amplitude were relatively more common in the subgroup with a decreased FEV1 o, but the differences observed were not significant A terminal notching of the QRS was not associated with impaired ventilatory capacity in this series. Discussion The literature on ECG alterations consistent with right ventricular overload and functional chronic disorders of pulmonary circulation is abundant The ECG abnormalities most often encountered are the various P wave changes, right axis deviation of the QRS, rS pattern in the chest leads, clockwise rotation of the QRS, and ventricular conduction defects (RBBB and IRBBB in particular) (Chappel, 1966 ; Kokkola, 1972; Scott, 1961) The items selected for this study included these and other indicators of cor pulmonale. The results obtained showed that the number of ECG abnormalities was higher among the subjects with asbestosis than among the referents, although the differences were not very large Low prevalences were found for high right R wave and right ventricular conduction defects, which are usually considered to be the most reliable indicators of right ventricular hypertrophy The rather low number of "pathological ECG" findings (in comparison with those of the referents) suggest that clinical cor pulmonale is not a very common disorder in asbestosis patients The analyses of the correlations between ECG and FEVL o lend support to this assumption as well The associations revealed were not strong In many instances the increase in the number of cor pulmonale findings was associated only with severe impairment in ventilatory capacity. Two aspects must be kept in mind when one assesses the relevance of the methodology used Firstly, the correlations between ECG and ventilatory function were examined according to classified variables This approach is obviously quite crude, since the limits for the categories are to a large extent arbitrary More accurate correlations could have been established in the regression analyses if the exact amplitude measures had been used for the ECG variables Secondly, as Punsar and Kokkola (1974) have demonstrated, the occurrence of concomitant left heart disease may affect the usefulness of the ECG variables in the diagnosis of pulmonary heart disease, particularly for the precordial variables In the present study the relatively small size of the asbestosis group did not allow this issue to be taken into consideration. Previous reports on ECG findings in asbestosis are very few in number. Tomasini and Sartorelli (1971) examined a series of 181 asbestosis patients and found right axis deviation of the QRS in 15, RBBB in two and P pulmonale in one patient They found no correlation between ECG signs and carbon monoxide

174

K Kokkola and M S Huuskonen

diffusion capacity Emara and El-Chawabi ( 1969) reported their observations on 29 asbestosis patients The most important findings consisted of left axis deviation of the QRS in nine, right axis deviation of the QRS in two, RBBB in four, and IRBBB in two cases P pulmonale was not present in any of the recordings The study group of Kleinfeld et al (1966) included 21 asbestos workers showing signs compatible with asbestosis No individual demonstrated ECG findings consistent with the major criteria of cor pulmonale Only one subject had a right-bundle-branch block. The results of the present paper do not completely concur with earlier findings The disparities are presumably attributable to differences in methodology and the materials included in the studies Of the patients 79 (65 8 %) revealed restrictive impairment and 13 (10 8 %) obstruction in lung function tests The pathogenesis of obstruction in these cases is not umbiguous, because smokers were not excluded from this study Consequently, the obstruction caused by asbestosis is probably less than 10 8 % among these patients. The basic patho-physiological mechanism for ECG alterations in chronic lung disease is the hypertrophy of the right ventricle, secondary to pulmonary hypertension However, numerous studies have demonstrated that ECG changes consistent with the cor pulmonale pattern can be elicited by other mechanisms as well Pulmonary hyperinflation due to airway obstruction and emphysema exert an undeniable effect on the ECG (Chappell, 1966 ; Kokkola, 1972 ; Kokkola and Sahlstr6 m, 1974 ; Millard, 1967 ; Schmock et al , 1971 a, 1971 b; Wasserburger et al., 1959 ; Zwi et al , 1971) The influence is either direct or due to positional alterations of the heart, e g , verticalisation, clockwise rotation, etc (Scott, 1961). Since the majority of earlier studies have dealt with the ECG in obstructive lung diseases, the differentiation of the basic mechanism is problematical. Wasserburger et al ( 1959) created the concept of ECG pentalogy for emphysema (P pulmonale, Ta in the inferior leads, vertical heart, clockwise rotation and low QRS amplitudes), which suggests that pulmonary emphysema and hyperinflation influenced ECG signs of cor pulmonale More recent papers have, to some extent, disagreed with the findings of Wasserburger et al Chappell ( 1966) stated that airway obstruction correlated with AP, P pulmonale and AQRS, but the presence or absence of emphysema did not influence ECG findings Very similar conclusions were obtained by Schmock ( 1971 b) and Zwi et al ( 1971) Schmock et al ( 1971 a) regarded P pulmonale as a sign of true RVH, while Millard ( 1967) suggested that only deep precordial S waves are correlated with emphysema in obstructive lung disease, the other ECG alterations being due to RVH This view was further supported by the findings of Kokkola and Sahlstr 6m ( 1974) in a series consisting of patients with pulmonary tuberculosis. The present series comprised patients with non-obstructive lung disease, asbestosis Thus, the ECG changes observed can be primarily attributed to "true cor pulmonale", although the series was not entirely free of subjects with some obstruction (e g , smokers) The ECG parameters exhibiting the best association with FEVL o were the P wave variables, transitional zone (clockwise rotation), and RV 5, 6 amplitude, while SV 56 amplitude failed to show any association with ventilatory capacity The result lends support to the conclusions drawn by Millard ( 1967), Schmock et al (1971 a), and Kokkola and Sahlstr 6 m ( 1974).

Electrocardiographic Signs of Cor Pulmonale in Asbestosis

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References Berglung, E , Birath, G , Bjure, J , Grimby, G , Kjellmer, J , Sandqvist, L , 56 derholm, B : Spirometric studies in normal subjects I Forced expirograms in subjects between 7 and 70 years of age Acta Med Scand 173, 185 (1963) Blackburn, H , Keys, A , Simonson, E , Rautaharju, P , Punsar, S : The electrocardiogram in population studies A classification system Circulation 21, 1160-1175 (1960) Chappell, A G : The electrocardiogram in chronic bronchitis and emphysema Br Heart J 28, 517-522 (1966) Emara, A , El-Chawabi, S : Correlation between the electrocardiogram and radiological picture in 29 cases of asbestosis J Egypt Med Assoc 52, 562-570 (1969) International Labour Office ILO-U/C international classification of pneumoconioses (Occupational safety and health series 22 (rev )), p 32 Geneva 1972 International Society of Cardiology: Research Committee, meeting at Makarska, September 1963, Br Heart J 26, 558-565 (1964) Kleinfeld, M , Messite, J , Shapiro, J : Clinical, radiological and physiological findings in asbestos Arch Intern Med 117, 813-819 (1966) Kokkola, K : Ventilatory function and electrocardiographic pattern of cor pulmonale in pulmonary tuberculosis Scand J Respir Dis lSuppl l 78 (1972) Kokkola, K , Punsar, S : Electrocardiographic low-frequency QRS notching and ventilatory impairment in patients with pulmonary tuberculosis Ann Clin Res 9, 73-78 (1977) Kokkola, K , Sahlstr 6 m, K : Pulmonary hyperinflation and the electrocardiogram in pulmonary tuberculosis Scand J Respir Dis lSuppl l 89, 227-233 (1974) Millard, J F C : The electrocardiogram in chronic lung disease Br Heart J 29, 43-53 (1967) Punsar, S , Kokkola, K : ECG pattern of cor pulmonale and ventilatory function in tuberculous patients with left heart disease Ann Clin Res 6, 86-92 (1974) Raunio, H : Initial and terminal notching of the QRS complex in the electrocardiogram. Academic dissertation, Kuopio 1970 Rose, G A , Blackburn, H : Cardiovascular survey methods World Health Organization, Geneva 1968 The Scandinavian Committee on ECG Classification: The Minnesota Code" for ECG classification Adaptation to CR leads and modification of the code for ECGs recorded during and after exercise Acta Med Scand lSuppl l 481 (1967) Schmock, C L , Mitchell, R S , Pomerantz, B , Pryor, R , Maisel, J C : The electrocardiogram in chronic airways obstruction The role of bronchitis and emphysema Chest 60, 335-340 (1971 a) Schmock, C L , Pomerantz, B , Mitchell, R S , Pryor, R , Maisel, J C : The electrocardiogram in emphysema with and without chronic airways obstruction Chest 60, 328-334 (1971 b) Scott, R C : The electrocardiogram in pulmonary emphysema and chronic cor pulmonale Am. Heart J 61, 843-845 (1961) Tomasini, M , Sartorelli, E : Frequenza dei segni electrocardiografici di cuore pulmonare cronico nell'asbestosis Med Lav 62, 549-553 (1971) Wasserburger, R H , Kelly, J R , Rasmussen, H K , Juhl, J H : The electrocardiographic pentalogy of pulmonary emphysema A correlation of roentgenographic findings and pulmonary function studies Circulation 20, 831-841 (1959) Zitting, A , Huuskonen, M S , Alanko, K , Mattsson, T : Radiographic and physiological findings in patients with asbestosis Scand J Work Environ Health 4, 275-283 (1978) Zwi, S , Kanarek, D J , Crosley, A I , Goldman, H I : The electrocardiogram in chronic bronchitis and emphysema S Afr Med J 45, 205-209 (1971) Received December 14, 1978 / Accepted February 5, 1979

Electrocardiographic signs of cor pulmonale in asbestosis.

International Archives of Int Arch Occup Environ Health 43, 167-175 (1979) Oeupalnal and Eilnmenta Health © Springer-Verlag 1979 Electrocardiograp...
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