Diagnosis and prognosis of ventricular infarction · evidentin 50%ofpatients studied byradionuclide...

Br Heart J 1986; 56: 19-26

Diagnosis and prognosis of right ventricularinfarction

E A RODRIGUES,* N G DEWHURST,t L M SMART,* W J HANNAN,$A L MUIR,t

From the Departments of *Cardiology, tMedicine, and tMedical Physics and Medical Engineering, RoyalInfirmary, Edinburgh

SUMMARY The values of several non-invasive methods for the diagnosis of right ventricularnecrosis in inferior myocardial infarction were compared in 51 consecutive patients whounderwent serial radionuclide ventriculography, pyrophosphate scintigraphy, and cross sectionalechocardiography. In addition a unipolar electrocardiographic lead V4R was recorded onadmission, daily, and during episodes of further pain. Profound right ventricular dysfunction wasevident in 50% of patients studied by radionuclide methods after inferior myocardial infarctionbut recognition on clinical groups alone was poor. Functionally important right ventricularinfarction was best detected and followed serially by radionuclide ventriculography.Echocardiographic methods for evaluating right ventricular ejection fraction correlated poorlywith radionuclide methods. Increased uptake of radioactivity by the right ventricle onpyrophosphate scintigraphy usually indicated poor right ventricular function, but a scan that wasnegative in the right ventricular territory did not exclude dysfunction. ST segment elevation inV4R was not specific for right ventricular infarction and its routine use may lead to overdiagnosisof this condition. Serial measurements suggest that profound right ventricular dysfunctionpersists after acute inferior infarction and is associated with considerable morbidity andmortality. Of 25 patients with severe right ventricular dysfunction, six died in the late hospitalperiod. In the remaining 19 patients mean right ventricular ejection fraction over a two monthperiod did not improve; six patients had persistent right ventricular dyskinesia and features ofchronic right ventricular failure developed in three survivors.

Right ventricular necrosis has been recognised atnecropsy for many years,1 2 but it was not until 1974that Cohn et al first described its potentially serioushaemodynamic consequences.3 Since then aware-ness of right ventricular infarction has increased andthe reported incidence in patients with acute inferiormyocardial infarction is 25X53%.4-6 Early recog-nition of right ventricular dysfunction is importantbecause the time of onset of its often profound hae-modynamic sequelae is unpredictable and these maybe prevented by the administration of an appropri-ate intravenous volume load. If right ventricular

Requests for reprints to Dr A L Muir, Department of Medicine,Royal Infirmary, Edinburgh EH3 9YW.

Accepted for publication 18 March 1986

infarction is neglected or treated as left heart failurewith diuretics cardiogenic shock may supervene.

Clinical recognition of right ventricular infarctionnow rests largely on a typical, though not uniformlypresent, clinical picture backed by evidence of rightventricular dilatation and dysfunction. Because rou-tine right heart catheterisation in every patientpresenting with acute inferior infarction is imprac-ticable, non-invasive diagnosis by electro-cardiographic or radioisotopic methods to detect orto raise the suspicion of important right ventricularnecrosis at an early stage would be helpful. Such anelectrocardiographic method was suggested byErhardt in 1974 who proposed that right ventricularinfarction could be diagnosed by elevation of the STsegment in the right precordial bipolar chest leadCR4R,7 and more recently there have been favour-able preliminary reports of the use of the more con-

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ventional unipolar chest lead V4R.8 In additioncross sectional echocardiography may be used tovisualise the right ventricle and assess its func-tion.9 10

In search of a reliable non-invasive diagnosticmethod we prospectively evaluated radioisotopeventriculography, pyrophosphate scintigraphy,echocardiography, and the electrocardiographic leadV4R to determine the prevalence, clinical impli-cations, and prognosis of right ventricularinvolvement in acute infarction of the inferior myo-cardial wall.

Patients and methods

PATIENT POPULATIONWe studied 51 consecutive patients (13 women and38 men, mean age 59 (range 36-73)) admitted to acoronary care unit with acute infarction of the infe-rior myocardial wall. None had evidence of previousmyocardial infarction. In all patients ischaemic chest

Rodrigues, Dewhurst, Smart, Hannan, Muir

pain lasted longer than 30 min and was followed byelectrocardiographic abnormality in leads II, III,and aVF with evolutionary ST segment/T wavechanges or the appearance of Q waves or both.Myocardial infarction was confirmed in all cases bya significant rise in serum activity of at least twoenzymes (creatine kinase, aspartate aminotransfer-ase, or lactate dehydrogenase). Clinical right ven-tricular infarction was diagnosed if three or more ofthe following were present simultaneously within 48hours of admission-persisting hypotension (sys-tolic blood pressure < 100 mm Hg), raised jugularvenous pressure, clear lung fields (clinically andradiographically), and oliguria (< 300 ml urine per24 hours or <10 ml urine per hour for two con-secutive hours).

ELECTROCARDIOGRAPHYA unipolar right chest lead V4R was recorded with aconventional 12 lead electrocardiogram on admis-sion, daily for four days, and during any further epi-

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*X.><U:,:' :'^'t,,u,.';<.^....'.ts.!'X,.'.:-''<~~~~~~~~~~~~~~~~~....Fig. 1 Pyrophosphate scintigrams showing positive and negative pyrophosphate uptake. R V, rightventricle; LV, left ventricle.



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Diagnosis and prognosis of right ventricular infarction

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ELRight ventricular ejection fraction (RNV)

Fig. 2 Distribution of right ventricular ejection fractiondetermined byfirst pass radionuclide angiography 2-4 daysafter inferior infarction. RNV, radionuclideventriculography .

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sodes of chest pain. ST segment elevation wasregarded as important if it was > 0 5 mm above theisoelectric line.

NUCLEAR VENTRICULOGRAPHYRight ventricular function was initially estimated atday 2-4 from a gated bolus of 800 MBq oftechnetium-99m pyrophosphate imaged in the 300right anterior oblique projection over 7-15 cardiaccycles by a Siemens high resolution LEM gammacamera that was appropriately positioned after atransmission scintigram had been obtained from aposteriorly positioned flood source. Right ventricu-lar ejection fraction was derived from the first passdata by the techniques previously described by thislaboratory.'1 Thereafter right and left ventricularejection fractions were calculated from a gated bloodpool equilibrium study with phase analysis ofimagesgenerated over 500 cardiac cycles and acquired inthe 300 left anterior oblique projection by means of

V4 R Negative V3 R Pbsitive V3 R Negative

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Fig. 3 Comparison between radioisotopically determined right ventricular ejectionfraction and STelevation in leads V4R and V3R. RNV, radionuclide ventriculography.

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Positive Negativepyrophosphate scintigraphy

Fig. 4 Comparison between radioisotopically determinedright ventricular ejection fraction and results ofpyrophosphate scintigraphy. RNV, radionuclideventriculography.


450 left anterior oblique projection, radioactivitywas present anterior to the interventricular septumand posterior and directly adjacent to the bony chestwall (Fig. 1).

ECHOCARDIOGRAPHYCross sectional echocardiography was attempted in38 patients during their hospital stay (days 3-5) andrepeated eight weeks later using an Irex 3 real timephased array imaging system and a 2'5 MHz trans-ducer. Cross sectional echocardiograms of the rightventricle were obtained in the parasternal long axisview, parasternal short axis views at the level of theaortic and mitral valves, and in the apical four cham-ber view. Echocardiograms were recorded on video-tape for subsequent play back. End systolic and enddiastolic dimensions of the right ventricle were mea-sured in each view by means of stop frame analysis,and we used average chamber dimensions to calcu-late right ventricular ejection fraction by the formulashown9: RVEF= (]Ded2-fles2) . fed2, where f5edis mean end diastolic dimension and 15es is meanend systolic dimension.Electrocardiography, scintigraphy, blood pool

ventriculography, and echocardiography were per-formed and interpreted by independent observers.Statistical analysis was performed by the pairedStudent's t test and conventional linear regressionformulas.

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single region of interest methods. Estimation ofright and left ventricular ejection fractions wererepeated at day seven and at week eight by gatedblood pool ventriculography after the injection of800 MBq of 99mTc labelled human serum albumin.

PYROPHOSPHATE SCINTIGRAPHYMyocardial infarct scintigraphy was performed atday 2-4, two hours after the injection of 800 MBq of99mTc pyrophosphate. Images were recorded in theanterior and 450 left anterior oblique projections.Scintigrams were graded on a scale from 0 to 4 onthe basis of the level of radioactivity in the cardiacregion: 0, no activity; 1, slight indefinite activity; 2,definite activity but less intense than bone; 3, activ-ity equal to bone; 4, activity greater than bone. Scin-tigrams graded > 3 were considered to be abnormal.In addition, the area of increased left ventricularuptake was described as inferior or inferolateral witheither anterior or posterior extension. Right ventric-ular infarction was deemed to be present if, in the

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0 0-1 0.2 0-3 0.4RVEF (echo)

I i I0*5 0*6 0.7

Fig. 5 Comparison between right ventricular ejectionfraction (RVEF) determined by radionuclideventriculography (RNV) and echocardiography (echo).

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o LVEFo RVEF- Equilibrium blood pool ventriculography-x- First passventriculography--- Echocardiogruphy

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Time (week)

Fig. 6 W-RigJRVEF) andieft ventricular ejection fraction(LVEF) one week and eight weeks-after acute inferiormyocardial infarction.

Results

Figure 2 shows the range of right ventricular ejec-tion fractions determined by radionuclide nwhodsin the acute stage. Severe right ventricular 3dys-function was noted in 25 patients in whom the-meanright ventricular ejection fraction was <0 25 (nor-mal range 0'53-0 71).- The condition was diagnosedclinically in only three of these patients (mean rightventricular ejection fraction 0 16). All three weretreated by volume loading, which greatly improvedtheir clinical state. In retrospect eight other patients-with mean right ventricular ejection fraction of 0 16had some of the clinical features of right ventriculardysfunction which were not recognised clinically atpresentation, and without exception they had a com-plicated acute phase with persisting hypotension andoliguria. A further 14 patients with a mean rightventricular ejection fraction of 0X21 had no clinicalfeatures of right ventricular dysfunction.

ELECTROCARDIOGRAPHYForty eight patients developed new abnormal Qwaves in the inferior leads. Acute ST/T changes inthe absence of Q waves developed in two patientsand one patient had left bundle branch block. Figure3 shows the results of radioisotopically determinedright ventricular ejection fraction and the presenceor absence of ST segment changes in the right chestlead. When the ST segment elevation in lead V4Rwas > 0-5 mm it had a sensitivity of92% for diagno-sis of severe right ventricular dysfunction (right

23ventricular ejection fraction < 025) but a specificityof only 40%. Compared with pyrophosphate scin-tigraphy ST elevation in V4R had a similar sensi-tivity (88%) but specificity was 42%.

PYROPHOSPHATE SCINTIGRAPHYPyrophosphate scintigraphy confirmed inferiorinfarction in all 51 patients and increased right ven-tricular uptake was noted in 25. Uptake wasincreased in the following regions of the left ventri-cle: inferior (39), inferolateral (5), posterior exten-sion (3), anterior extension (2), diffuse uptake (2). Ascan positive in the right ventricular territory usu-ally indicated poor right ventricular function butthree patients with right ventricular dysfunction hadnegative scans (Fig. 4).

ECHOCARDIOGRAPHYEchocardiography was attempted in 38 patients, andin two patients echocardiograms were of inadequatequality for examination. The right ventricular ejec-tion fraction that was determined echocardio-graphically correlated poorly with that measured bythe radioisotope technique (r = 0 43) (Fig. 5).

FOLLOW UPSerial measurements in this group showed that therewas a significant improvement in both right and leftventricular ejection fraction in the two months afterinfarction that was detected by first pass and equi-librium blood pool ventriculography and by echo-cardiography (Fig. 6). There was a significant cor-relation between first pass and equilibriumradionuclide methods for measuring right ventricu-lat ejection fraction (r = 0-93). Improvement inright ventricular function, however, was limited tothose patients who had moderate to good right

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PoorRV function(RVEF <0-25)

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Moderate to goodRV function(RVEF >0.25)

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. ~~I i1 8 1 8

Time (weeks)

Fig. 7 Right ventricular ejection fraction (RVEF) oneweek and eight weeks after acute inferior infarction. Theresponse of those with initially poorfunction is compared withthat of those with initially goodfunction.



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ventricular ejection fraction soon after infarction(Fig. 7). In those with early severe right ventriculardysfunction no improvement was detected. In thisgroup there were six late hospital deaths, and threeof the survivors developed features of predominantchronic right heart failure.

Discussion

Necropsy studies have shown that involvement ofthe right ventricle in acute inferior myocardialinfarction is more common2 1213 than its recog-nition and treatment in routine clinical practicewould suggest. In the clinical setting there is no sub-stitute for right heart catheterisation to identify thederanged haemodynamic function produced byright ventricular infarction and to monitor treat-ment, but use of this technique in all patientspresenting with acute inferior myocardial infarctionis impracticable and unnecessary. In addition, with-out fluoroscopy interpretation of the pressure tracemay be misleading3 and ascertaining the preciselevel of right ventricular end diastolic pressure maybe difficult,'4 but this is critical if this variable is tobe used as the only haemodynamic index of rightventricular infarction. Moreover, in the series ofCandell-Riera et al eight of 18 patients with inferiorinfarction and scintigraphic evidence of right ven-tricular involvement had no definite haemodynamicevidence of right ventricular dysfunction.'5 Thus itmay be that pressure monitoring will detect onlygross dysfunction of the right ventricle, whereas theejection fraction may be abnormal long before thereis any increase in pressure. Using haemodynamiccriteria alone, Candell-Riera et al found that 36% ofpatients had right ventricular infarction,'5 whereasErhardt and Isner and Roberts in their necropsyseries reported rates of 45% and 50%respectively.7 16 Reliance on invasive haemo-dynamic measurements alone may therefore lead tounderdiagnosis.We found that the right ventricle was affected in

50% of patients with acute inferior wall infarction asdetected by radionuclide ventriculography or pyro-phosphate scintigraphy and this accords with thestudies of Sharpe et al, Garty et al, and Croft et alwho have reported frequencies of 40%, 52-7%, and47.6% respectively.5 17 18

CLINICAL FEATURESThe clinical signs of right ventricular decom-pensation have already been mentioned. Clinicalrecognition of right ventricular infarction is pooreven when the whole syndrome is present. In ourstudy only 12% of cases of severe right ventriculardysfunction were detected clinically and all of these


patients responded well to an appropriate intra-venous volume load. A further eight patients had acomplicated acute phase with some of the clinicalfeatures of right ventricular involvement; they didnot receive volume loading and they were sub-sequently shown to have poor right ventricular func-tion. In cases in which the clinical index of suspicionis high further evidence from invasive or non-invasive investigation may be necessary to overcomereluctance to administer an appropriate volumeload.

ELECTROCARDIOGRAPHYST elevation in the right precordial lead V4R hasbeen reported to be a sensitive and specific index ofright ventricular infarction.7 8 Other workers havefound the test to be less specific, however, with 10%of patients with acute anterior infarction showing asimilar elevation.'7 Similarly, false positives mayoccur in patients with pericardial diseases and leftbundle branch block. Our study suggests that STelevation in V4R is a more sensitive indicator ofright ventricular dysfunction than radioisotopemeasurements but that its lack of specificity maylead to overdiagnosis.

PYROPHOSPHATE SCINTIGRAPHYVarious workers have pointed out the special role ofpyrophosphate scintigraphy in the diagnosis of rightventricular infarction.5 19 20 As an isolated pro-cedure, however, it has limitations for detecting allpatients with right ventricular necrosis, mainlybecause it depends on the delineation of a smallamount of radioisotope in the right ventricular freewall that is partly concealed by the bony skeleton. Inaddition, maximum pyrophosphate accumulationoccurs in myocardial regions where blood flow isreduced to 30-40% of normal.2' With lower flowrates pyrophosphate uptake falls despite theincreasing degree of necrosis. The chance ofdetecting necrosis is highest between 36-72 hoursafter the onset of chest pain.22 Any delay in scanningfor whatever reason will lead to false negative scans.Furthermore, other conditions (for example unsta-ble angina and defibrillation) have been shown togive false positive pyrophosphate scans. Given theselimitations, we have shown that right ventricularpositive pyrophosphate scans are usually indicativeof poor right ventricular function but a scan with noapparent uptake in the right ventricular territorydoes not exclude the diagnosis.

ECHOCARDIOGRAPHYA few studies have assessed the value of echo-cardiography in the detection of right ventricularinfarction.'0 23 24 The limitations of M mode echo-



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Diagnosis and prognosis of right ventricular infarction 25

cardiography in evaluating patients with coronaryartery disease and segmental wall motion abnormal-ities are well recognised. Various abnormalities havebeen demonstrated by cross sectional echo-cardiography in patients with right ventricularinfarction; these include segmental dyskinesia,paradoxical septal motion, dilatation of the rightventricle, tricuspid incompetence, and localisedpericardial effusions. Using cross sectional echo-cardiography, we obtained images of the right ven-tricle in several views. Patient build, relative inac-cessibility of the adult right ventricle, its complexgeometry, and difficulty in delineating endocardialsurfaces accurately may have accounted for the poorcorrelation with first pass and equilibrium radio-nuclide methods that are unaffected by such vari-ables.

RADIONUCLIDE VENTRICULOGRAPHYRadionuclide ventriculography has been used exten-sively to study both left and right ventricular func-tion and count based methods have been used toovercome some of the problems of complex geome-try of the right ventricle.25 Because of the theoreticaldifficulties with gated blood pool studies for analysisof right ventricular function, we performed bothfirst pass and gated studies in our patients. We suc-cessfully excluded right atrial counts by phase anal-ysis, and this gave a good correlation (r = 0-9)between the two radionuclide methods for deter-mining right ventricular ejection fraction.

Right ventricular ejection fraction varies widely innormal subjects25 26; in our laboratory the normalrange is 0-530-71. Garty et al regarded a right ven-

tricular ejection fraction of <045 as evidence ofright ventricular infarction; thus they includedpatients with very mild right ventricular dys-function.'7 When they used this criterion theyfound that low right ventricular ejection fraction hasa low specificity for detection of right ventricularinfarction. For the purposes of our study, severeright ventricular dysfunction was taken to be a rightventricular ejection fraction of <0-25, and 50% ofour patients fell into this category. Our date showthat use of stricter criteria for right ventricular dys-function enhances the specificity of the test.On the basis of radioisotopically determined right

ventricular function, it was possible to categorisepatients into low and high risk groups and thusobtain some indication of prognosis. Previous stud-ies have shown that patients with right ventricularinfarction have a higher complication rate andpoorer prognosis than those in whom the right ven-tricle is not affected.8 16 Our data suggest thatpatients with right ventricular infarction fall intotwo groups: those with slight impairment of func-

tion whose clinical condition improves as the rightventricular ejection fraction increases and those withearly severe right ventricular dysfunction who havea higher late hospital mortality (24%) and in whomlow right ventricular ejection fraction persists withassociated complications after discharge from hospi-tal.We found radionuclide angiography to be a useful

non-invasive investigation for the detection of rightventricular infarction in patients with inferiorinfarction that was better than electrocardiographicor echocardiographic methods. The technique isuseful for indicating which patients may benefitfrom invasive haemodynamic monitoring and it alsoindicates short term prognosis after inferiorinfarction.

This work was supported by a grant from theScottish Home and Health Department.

References

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