Br HeartJ 1984; 52: 136-9

Computed tomography in patients with hypertrophiccardiomyopathyDAVID L STONE, M C PETCH, G I VERNEY, A K DIXON

From the Departments of Cardiology and Radiology, Papworth and Addenbrooke's Hospitals, Cambridge

SUMMARY Computed tomography was undertaken in nine patients (age range 33-69 (mean 48.7)years) with hypertrophic cardiomyopathy. The ventricular septum was demonstrated in each patientand shown to be thickened (mean 25 mm at maximum width). The results agreed with thoseobtained by echocardiography, except in two patients in whom computed tomography showedpreferential thickening of the mid-portion of the ventricular septum. The ventricular free wall was

not clearly seen.Computed tomography may prove a valuable technique in the assessment of patients with hyper-

trophic cardiomyopathy.

Computed tomography has proved to be a valuabletechnique in the diagnosis of aortic dissection,'<1pericardial disorders,45 and cardiac tumours.6 It mayidentify patent coronary artery bypass grafts7 and leftventricular thrombus.8 We report its use in patientswith hypertrophic cardiomyopathy diagnosed byechocardiography or at cardiac catheterisation.

Patients and methods

Nine patients were studied (eight men, one woman).Their ages ranged from 33-69 (mean of 48-7) years.The Table shows the clinical data. In all the patientsthe diagnosis had been made on clinical criteria andconfirmed by M mode echocardiography and in fivecases by cardiac catheterisation.

All the investigations were carried out on a SiemensSomaton 2 CT scanner. This is a rotate-rotate com-puted tomographic system capable of rapid sequencescans. For the studies in this report, the scan timeused was 5 s and the slice thickness 8 mm, and allimages were obtained at full inspiration. The patientwas initially positioned within the gantry and 3-4 pre-contrast images were obtained at differing anatomicallevels. These were used to estimate the position of the

ventricular septum before the contrast study. Fifty

Requests for reprints to Dr D L Stone, Regional Cardiac Unit, Pap.worth Hospital, Papworth Everard, Cambridge CB3 8RE.

Accepted for publication 23 March 1984

millilitres of contrast medium (Conray 420) were theninjected into a large peripheral arm vein, 30 ml as abolus and the remaining 20 ml more slowly during thenext 20 s. The first scan was obtained immediatelyafter the bolus, again at full inspiration. Five furthercontrast enhanced images were then obtained asrapidly as possible during the next minute. Ourmachine has a 5 s interscan time thus allowing normalrespiration between scans. The six postcontrastimages were obtained at 5 mm anatomical incrementsso that there was every chance of getting at least twosatisfactory images of the septum. In some patients anattempt was made to align the plane of the scan to thelong axis of the heart by gantry angulation after aninitial lateral scanogram.Measurements of septal thickness were subse-

quently made with electronic calipers on the evalua-tion console. A standard window width (256Hounsfield Units) was used for viewing. The level wasthen adjusted until the contrast medium in the cham-bers was in the middle of the grey scale (often around+ 100 HU).

Results

The Table and Figs. 1-5 show the results. In fourpatients, the septum was appreciably thickened (Figs.1-4). In case 7, the septum had a "diamond"configuration measuring 28 mm at its maximum (Fig.1). In all patients the septum was thickest in its mid-portion, and the values shown in the Table are themaximum widths of the septum. In case 2 there was

136

on Decem

ber 25, 2020 by guest. Protected by copyright.

http://heart.bmj.com

/B

r Heart J: first published as 10.1136/hrt.52.2.136 on 1 A

ugust 1984. Dow

nloaded from

Computed tomography in patients with hypertrophic cardiomyopathyTable Clinical data and results ofechocardiography and computed tomography in nine patients with hypertrophic cardiomyopathy

Case Age Sex Symptoms Signs Cardiac ECG M mode Rest PESP Cowony LV ComWutedNo (yr) diameter echoadogp pressre (mm Hg) artey angogram tomography

(cm)* gradient disease (septal size)(mmg Hg)

1 48 M Palpitation Ejection - LA +, LVH Septum 22 mm 110 170 LAD, HCM 23 mmmurmur RCA

2 62 M Dyspnoea, Pansystolic 14-5 LA +, LVH Septum not 80 - RCA HCM 25 mm,angina murmur defined, calcium present

calcium invalve ring

3 42 M Dyspnoea, Ejection 12.5 Left axis Septum 20 mm, - - - - 33 mm, diamondchest pain murmur deviation, SAM, aortic configuration

septal valve closureQ waves

4 69 M Dyspnoea, Pansystolic 14 Normal Small LV, 10 105 Minor HCM 17 mmangina, syncope murmur septum

17 mm5 49 M Tiredness Ejection 165 LVH Septum 30 mm - - - - 36 mm (inter-

murmur, atrial septumjerky enlarged)carotid pulse

6 34 M Congestive Ejection 18 LVH Septum 27 mm 85 106 None HCM, 26 mmfailure murmur MR

7 33 F Congestive Ejection 15 LVH, left axis Septum 18 mm, 100 150 None HCM 28 mm, diamondfailure, murmur, LV + deviation SAM, small LV configurationdyspnoea and jerky

carotid pulse8 50 M Dyspnoea, Ejection 15 LVH Septum 20 mm - - - - 19 mm

palpitation, murmuratypical chestpain

9 51 M Syncope Systolic 17 LVH Septum 20 mm - - - - 19 mmmurmur, LV +

*Radiographic.LVH, left ventricular hypertrophy; SAM, systolic anterior motion of the mitral valve; LA+, left atrial hypertrophy; LV+, clinical left ventricularenlargement; LAD, left anterior descending; RCA, right coronary artery; HCM, hypertrophic cardiomyopathy; MR, mitral regurgitation; PESP,postextrasystolic pressure gradient.

pronounced intracardiac calcification, which pro-duced linear artefacts (Fig. 2). The thick septum is,however, clearly seen. In case 5 there was some thick-ening of the interatrial septum as well as gross thick-ening of the interventricular septum (Fig. 3). Thiswas not so prominent in any of the other patients. Incase 3 there was once again a diamond configuration

Fig. 1 Case 7 (33 year old woman): computed tomogramshowing the intervuricular septum (S) most thickened (28 mm)in its mid-portion so forming a "diamond"configuraion. R,right ventricle; L, left ventricle.

with an appreciably thickened septum and a poorlydefined left ventricular free wall (Fig. 4). The septummeasured 33 mm at its maximum thickness.The Table shows the results of M mode echocar-

Fig. 2 Case 2 (62year old man): computed tomogram showingltnear artefactsfrom mitral nng caktfication (C), which degradethe image; neverthekss, the septum (S) is well seen (25 mmmaximmt). R, right ventrick; L, kft ventrick.

137

on Decem

ber 25, 2020 by guest. Protected by copyright.

http://heart.bmj.com

/B

r Heart J: first published as 10.1136/hrt.52.2.136 on 1 A

ugust 1984. Dow

nloaded from

Stone, Petch, Verney, Dixon

Fig. 5 Normal subject: computed tomogram clearly showingthe septum (S) (measured at II mm) between the right (RV) andleft (LV) ventricles.

Fig. 3 Case 5 (47year old man): comPuted tomogram showing

that the intermentricular septum (S) becomes progressively thickertowards the apex (reaching 36 mm). Posteriorly the ventricularseptum merges with quite a thick interatrial septum. R, rightventricle; L, left ventricle.

Fig. 4 Case 3(42year old man): computed tomogram showvinga diamond shape to the septum (S). R, right ventricle; L, leftventicle.

diography as well as computed tomography. In allnine patients the septum was clearly seen on com-puted tomography, and in eight of the nine patientsMmode echocardiography identified the septum. Thepresence of other echocardiographic abnormalitiessuch as systolic anterior motion of the mitral valve or

early closure of the mitral valve is evident, but they donot bear any fixed relation to septal thickness. There

is agreement between the two methods except in cases3 and 7. Although both these had abnormally thick-ened septa on M mode echocardiography with systolicanterior motion of the mitral valve, the valuesobtained by computed tomography for septal thick-ness were greater. In both cases a diamond configura-tion was seen on computed tomography. For com-parison, Fig. 5 shows a cardiac computed tomogramfrom a normal subject. The septum is clearly definedand measures 11 mm at its maximum thickness.

Discussion

The computed tomographic findings in these patientswith hypertrophic cardiomyopathy diagnosed by clin-ical criteria, cardiac catheter, or echocardiographyshow that excellent tomographic images of the heartmay be obtained which provide adequate definition ofthe interventricular septum. In our studies the scantime was 5 s, which is of course extremely long forcardiac imaging. Despite this, the pictures are of ade-quate quality to allow measurement of the septum,and comparison with real time echocardiographyshows remarkably good agreement. The normal(mean (SD)) septal width has been previouslyreported as 0 8 (0 6) cm, and in all our cases the sep-tum was appreciably thickened.9 The technique wasable to demonstrate the septum far more clearly thanthe free wall. A possible explanation for this may bethat the movement of the septum is less than the freewall, and therefore it is more clearly seen despite thelong data acquisition time. Certainly in patients withleft ventricular aneurysms the free wall of the aneur-ysm is clearly seen, presumably because it is relativelyimmobile.

138

on Decem

ber 25, 2020 by guest. Protected by copyright.

http://heart.bmj.com

/B

r Heart J: first published as 10.1136/hrt.52.2.136 on 1 A

ugust 1984. Dow

nloaded from

Computed tomography in patients with hypertrophic cardiomyopathyIt must not be forgotten that the information

obtained is anatomical, and the technique is there-fore limited in its application to such a dynamic organas the heart. The use of stop action or electrocardiog-ram gated tomography'01' has been described forcardiac computed tomography. These techniques,however, increase the overall scan time substantiallyand also do not eliminate motion artefacts due torespiration.The two cases in which the computed tomographic

measurements exceeded those of M mode echocar-diography are of interest. In both, a diamond septalconfiguration was seen on computed tomography.The variability in septal thickness has been reportedpreviously by angiographic techniques in hyper-trophic obstructive cardiomyopathy,'2 a possiblereason being that the echocardiographic beam did nottransverse the thickest part of the septum and there-fore the value obtained was less than that for com-puted tomography.A comparison of the relation of septal to free wall

thickness, as has been reported for echocardio-grams,'3 14 could not be made because of the rela-tively poor definition of the free wall. A septal to freewall ratio > 1.3: 1 is, however, now not felt to be diag-nostic of hypertrophic cardiomyopathy,'5 16 and ourfindings would suggest that this may be due to thevariable thickness of the septum in its different parts,as suggested by certain echocardiographicreports. 17 18

Intracardiac calcium, as seen in case 2, is notunusual in patients with hypertrophic car-diomyopathy, particularly if they are elderly.'9Calcification is readily detected by computed tomo-graphy, but Fig. 2 shows the linear artefacts that mayarise and which may prove a limitation in patientswith prosthetic valve rings or clips on vein grafts.Despite the artefacts we were able to define septalthickness in the patient in case 2, when the echocar-diogram was unable to show the septum adequately.

In conclusion, this study has shown that computedtomograhy may define the interventricular septum inpatients with hypertrophic cardiomyopathy. Theinformation it provides is anatomical but may be valu-able in patients with this condition especially ifechocardiography is technically difficult or unexpec-tedly normal.References

1 Moncada R, Salinas M, Churchill R, et al. Diagnosis ofdissecting aortic aneurysm by computed tomography.Lancet 1981; i: 238-41.

2 Heiberg E, Wolverson M, Sundaram M, Connors J,Susman N. CT findings in thoracic aortic dissection.AJR 1981; 136: 13-7.

3 Egan TJ, Neiman HL, Herman RJ, Malave SR, SandersJH. Computed tomography in the diagnosis of aorticaneurysm dissection or traumatic injury. Radiology 1980;136: 141-6.

4 Tomoda H, Hoshiai M, Furuya H, et al. Evaluation ofpericardial effusion with computed tomography. AmHeart J 1980; 99: 701-6.

5 Houang MTX, Arozena X, Shaw DG. Demonstration ofthe pericardium and pericardial effusion by computedtomography. 7 Comp Asst Tomogr 1979; 3: 601-3.

6 Godwin JD, Axel L, Adams JT, Schiller NB, SimpsonPC Jr, Gertz EW. Computed tomography: a new methodfor diagnosing tumor of the heart. Circulation 1981; 63:448-5 1.

7 Kahl FR, Wolfman NT, Watts LE. Evaluation of aor-tocoronary bypass graft status by computed tomography.Am J Cardiol 1981; 48: 304-10.

8 Nair CK, Sketch MH, Mahoney PD, Lynch JD, MoossAN, Kenney NP. Detection of left ventricular thombi bycomputerised tomography. BrHeartJ 1981; 45: 535-41.

9 Guthaner DF, Wexler L, Harell G. CT demonstration ofcardiac structures. AJR 1979; 133: 75-81.

10 Harell GS, Guthaner DF, Breiman RS, et al. Stop-actioncardiac computed tomography. Radiology 1977; 123:5157.

11 Sagel SS, Weiss ES, Gillard RG, et al. Gated computog-raphy of the human heart. Investigative Radiology 1977;12; 56-3-6.-

12 Redwood DR, Scherer JL, Epstein SE. Biventricularcineangiography in the evaluation of patients withasymmetric septal hypertrophy. Circulation 1974; 49:1116-21.

13 Henry WL, Clark CE, Epstein SE. Asymmetric septalhypertrophy. Echocardiographic identification of thepathognomonic anatomic abnormality of IHSS. Circula-tion 1973; 47: 225-33.

14 Abbasi AS, MacAlpin RN, Eber LM, Pearce ML. Leftventricular hypertrophy diagnosed by echocardiography.N Engl J Med 1973; 289: 118-21.

15 Feizi 0, Emanuel R. Echocardiographic spectrum ofhypertrophic cardiomyopathy. Br Heart J 1975; 37:1286-302.

16 Shah PM. Echocardiography in the diagnosis of hyper-trophic obstructive cardiomyopathy.Am J Med 1977; 62:830-5.

17 Tajik AJ, Seward JB, Hagler DJ. Detailed analysis ofhypertrophic obstructive cardiomyopathy by wide-angletwo-dimensional sector echocardiography [Abstract]. AmJ Cardiol 1979; 43: 348.

18 Taylor RD, Child JS, Shah PM. Variations in septalhypertrophy in hypertrophic obstructive car-diomyopathy [Abstract]. Am Jf Cardiol 1979; 43: 348.

19 Kronzon I, Glassman E. Mitral ring calcification inidiopathic hypertrophic subaortic stenosis. Am J Cardiol1978; 42: 60-6.

139

on Decem

ber 25, 2020 by guest. Protected by copyright.

http://heart.bmj.com

/B

r Heart J: first published as 10.1136/hrt.52.2.136 on 1 A

ugust 1984. Dow

nloaded from