Echocardiographic Evaluationof Ventricular Septal Aneurysms

A. REBECCA SNIDER, M.D., NORMAN H. SILVERMAN, M.D., NELSON B. SCHILLER, M.D.,AND THOMAS A. PORTS, M.D.

SUMMARY The spontaneous closure of ventricular septal defects is frequently associated with septalaneurysm formation. In this paper we discuss the M-mode and two-dimensional echocardiographic findings innine children with aneurysms of the ventricular septum in association with ventricular septal defects. In allpatients the diagnosis was confirmed by angiography. The ventricular septal aneurysms were detected by bothM-mode and two-dimensional echocardiography. With M-mode echocardiography, septal aneurysms could berecognized by a pattern of multiple systolic echoes within the right ventricle. With two-dimensional echocar-diography, the protrusion of the septal aneurysm into the right ventricle could be seen from several views andthe location and the relative size of the aneurysm assessed. Echocardiographic techniques useful in the detec-tion of ventricular septal aneurysms are discussed and examples presented.

RECENT STUDIES of the natural history of ventric-ular septal defects suggest a continuing rate of spon-taneous closure throughout childhood.' 4 Diminutionand spontaneous closure of membranous ventricularseptal defects through aneurysm formation have beenwell documented.5`7 The formation of a ventricularseptal aneurysm is frequently the prelude to completeclosure of the septal defect or partial closure withdiminution in the size of left-to-right shunt.5Therefore, if a ventricular septal aneurysm can bedetected reliably by a noninvasive technique, repeatedcardiac catheterization may be avoided. In this paperwe present the M-mode and two-dimensional echocar-diographic findings of nine patients with ventricularseptal aneurysm in association with ventricular septaldefect. The reliability of both echocardiographictechniques is assessed.

Materials and Methods

Nine patients with ventricular septal aneurysm inassociation with ventricular septal defect were studiedby M-mode and two-dimensional echocardiography.They ranged in age from 1 week to 13 years. Allpatients underwent cardiac catheterization for evalua-tion of the severity of the ventricular septal defect.Complete cardiac catheterization data, including oxi-metric shunt determinations and biplane right and leftventricular cineangiograms, were available for allpatients. The catheterization and angiographic studieswere done within 2 weeks of the echocardiograms. Thediagnosis of ventricular septal aneurysm was based onthe angiographic demonstration of tissue with distinc-tive margins protruding from the membranous ven-tricular septum into the right ventricle with eachsystole' 9 (fig. 1).

All patients had M-mode and two-dimensional

From the Departments of Pediatrics and Medicine and the Car-diovascular Research Institute, University of California, San Fran-cisco, California.

Address for reprints: Rebecca Snider, M.D., C-344, University ofCalifornia, San Francisco, California 94143.

Received April 21, 1978; revision accepted December 8, 1978.Circulation 59, No. 5, 1979.

echocardiographic studies before cardiac catheteriza-tion. The echocardiograms were interpreted by twoobservers who did not know the angiographic results.M-mode echocardiograms were performed using anEkoline 20A ultrasonoscope interfaced with a stripchart recorder. A variety of transducers of differingfocal length and frequency appropriate for thepatient's size were used. Recordings were performedwith the patient in the left lateral decubitus position,with the transducer positioned in the third or fourthintercostal space at the left sternal border. The ultra-sound beam was directed to obtain the left ventric-ular, mitral valve and aortic root echoes in the usualmanner and then angled to the patient's right to obtainechoes in the plane of the tricuspid valve.'0 From thisposition the transducer was then angled toward theleft shoulder to obtain a sweep of the right ventricularoutflow tract.

All patients were studied by two-dimensionalechocardiography with a prototype of a VarianAssociates 32-element, phased-array, wide-angle (80°)sector scanner, now commercially available. Thepatients were examined in the left lateral decubitusposition with the transducer in the second or third in-tercostal space. Two-dimensional images were ob-tained in the long-axis, or sagittal, plane by directingthe tomographic plane between the apex and base ofthe heart. Short-axis, or transverse, views were ob-tained by directing the plane of sweep along a linedrawn between the right hip and left shoulder, perpen-dicular to the long axis of the left ventricle." Theapical four-chamber view was also obtained in allpatients. For this view the transducer was placed overthe cardiac apex and angulated in such a way as tovisualize simultaneously all four of the cardiacchambers.'2 The two-dimensional echocardiographicimages were permanently recorded on videotape forfuture analysis. The illustrations presented here wereobtained from Polaroid photographs of stop-action,single-frame, scan images made from the videotaperecordings. This photographic process results in amarked reduction in image quality, as well as a loss ofthe visual appreciation of motion normally present inthese phased-array, real-time recordings.

920

by guest on May 24, 2018

http://circ.ahajournals.org/D

ownloaded from

ECHO EVALUATION OF SEPTAL ANEURYSMS/Snider et al.

WYV

FIGURE 1. The top panel shows a lateral right ventricularangiogram with a filling defect caused by protrusion of a

ventricular septal aneurysm (arrows) into the right ventric-ular outflow tract. The bottom panel is a lateral left ventric-ular angiogram from the same patient.

Results

All patients had technically adequate M-mode andtwo-dimensional echocardiograms. Table 1 sum-marizes the clinical and hemodynamic data.

M-mode Echocardiographic Findingsof Ventricular Septal Aneurysm

Ventricular septal aneurysms were characterized onM-mode echocardiography in all cases by a pattern ofmultiple linear echoes moving into the right ventriclein systole. In the echocardiographic sweep of the rightventricle at the level of the tricuspid valve, the echoes

from the septal aneurysm appear anterior to theclosed systolic tricuspid valve echo and show a patternof abrupt systolic motion similar to the systolicanterior motion of the mitral valve seen in patientswith idiopathic hypertrophic subaortic stenosis.Figure 2 is a representative M-mode echocardiogramillustrating this pattern. The systolic anterior motionof the ventricular septal aneurysm was found in allnine patients. Often, abrupt systolic anterior motionof the echoes from the septal aneurysm permitted itsdifferentiation from the more gradual sloping systolicmotion of the closed tricuspid valve echoes. Withrespiratory variation in right ventricular cavity size,we observed an increase in the excursion of the septalaneurysm into the right ventricle with inspiration. Themultiple echoes from the ventricular septal aneurysmconsistently showed a high-frequency, low-amplitudeflutter (fig. 3).

Two-dimensional Echocardiographyof Ventricular Septal Aneurysms

Long-Axis View of Ventricular SeptalA neurysms

Using the long-axis view of the heart, in seven ofnine patients we visualized a saccular protuberancewith a rapid flicking motion extending into the rightventricle in systole and realigning with the ventricularseptum in diastole. This pattern was felt to represent aventricular septal aneurysm. Figure 4 is a systolicstop-frame image illustrating the ventricular septalaneurysm extending into the right ventricle from thehigh ventricular septum, just beneath the aortic valve.

Apex Four-Chamber View ofVentricular Septal AneurysmsWith cranial angulation from the apical four-

chamber view, the membranous interventricular sep-tum is visualized. The systolic bulging of the mem-branous septal aneurysms into the right ventricle wasvisualized in all nine patients with this modified apexfour-chamber view. In diastole the aneurysm realignswith the rest of the septum. This systolic expansionand diastolic realignment of the septal aneurysm wasseen in all patients with the apex four-chamber view.Figure 5 illustrates the two-dimensional echocardio-graphic appearance of a saccular aneurysm of themembranous septum as seen from the apex fourchamber view in a 5-year-old child.

Short-Axis View of Ventricular Septal AneurysmsWith the short-axis view of the heart at the level of

the aortic valve, the membranous interventricular sep-tum is viewed in cross section along with portions ofthe right ventricular outflow tract. As the septalaneurysm moved out of this plane in systole, the short-axis view permitted visualization of only four of thenine membranous septal aneurysms bulging into theright ventricular outflow tract. The protrusion of theseptal aneurysm into the right ventricle was seen withthis view, but the point of origin of the aneurysm fromthe interventricular septum could not be appreciated.

921

by guest on May 24, 2018

http://circ.ahajournals.org/D

ownloaded from

VOL 59, No 5, MAY 1979

TABLE 1. Clinical, Electrocardiographic, and Catheterization Data in Nine Patients with Ventricular Septal Aneurysm

Hemodynamic dataAge Diagnosis by QP/Qs PA pressure

Patient (years) ECG catheterization Recent Previous Recent Previous

JR 1 WNL VSD, VSA 2.5 26/14,20DD 13 WNL VSD, VSA 1.3 2.2 20/8,14 24/8,15AJ 5 RVCD, cannot VSD, VSA 1.3 2.7 45/20,35 75/40,50

rule out RVHTM 1 week WNL VSD, VSA 3.0 30/8,18DW 13 LAD, CC loop VSD, VSA 3.2 80/40,55

RVCD, cannot (LV = 130/4)rule out RVH

PH 12 LAD, BAE, 1-TGA, VSD, severe PS, 1.0 0.6 20/10,14 16/10,12LAH VSA

DP 11 WNL VSD, PDA, mild PS, 3.3 3.0 30/8,18 32/10,17VSA

MM 1 RVH ASD, VSD, VSA, 4.0 10.0 76/35,54 44/12,30reactive PAH

TW 9 WNL MS, VSD, VSA, post-op 1.0 25/12,16coarctation repair

Abbreviations: ASD - atrial septal defect; BAE = biatrial enlargement; CC loop = counterclockwise vector loop; LAD =left-axis deviation; LAH = left anterior hemiblock; 1-TGA = 1-transposition of great arteries; LV = left ventricular; MS =

mitral stenosis; PA = pulmonary artery; PAH = pulmonary artery hypertension; PDA = patent ductus arteriosus; PS pul-monic stenosis; Qp/Qs = pulmonic-to-systemic blood flow ratio; RVCD = right ventricular conduction delay; RVH rightventricular hypertrophy; VSA = ventricular septal aneurysm; VSD = ventricular septal defect; WNL = within normal limits.

In none of our patients did the septal aneurysmocclude the right ventricular outflow tract.

DiscussionAneurysms of the membranous interventricular

septum are small conical projections of thin mem-brane which arise from the margins of ventricular sep-tal defects. These aneurysms are generally small and

bulge 1-2 cm into the right ventricle in systole.'3 Thelength of these aneurysms, however, varies greatly,and some have been reported to extend considerabledistances into the right ventricle and produce someobstruction to the right ventricular outflow tract.14Aneurysms of the membranous ventricular septumwere initially believed to be congenital. There is nowevidence to suggest that aneurysms may develop in thecourse of spontaneous partial or complete closure of

FIGURE 2. M-mode echocardiogram dem-onstrating the abrupt systolic anterior mo-tion of the echoes from a ventricular septalaneurysm. The systolic excursion of theechoes from the ventricular septal aneurysmin this example is equal to the tricuspid valvediastolic excursion. MV= mitral valve;TV= tricuspid valve, VSA = ventricularseptal aneurysm.

CIRCULATION922

*0I

by guest on May 24, 2018

http://circ.ahajournals.org/D

ownloaded from

ECHO EVALUATION OF SEPTAL ANEURYSMS/Snider et al.

~~- - -. - -'

~~/

VSA_V , .'

VSAC,92~~~~~'~ .. 4~ ;T

ventricular septal defects, although their exactanatomic basis is controversial.6 7 Several series havereported that aneurysm formation is associated withdiminution in the functional size of membranous ven-tricular septal defects, and it appears that the forma-tion of aneurysms of the membranous septum is onemechanism of closure of ventricular septal defect.3' I

FIGURE 3. M-mode echocardiogram fromthe region of the tricuspid valve illustratingthe coarse systolic flutter of the echoesfromthe ventricular septal aneurysm. The systolicexcursion of the aneurysm is not clearly seenin this example. TV tricuspid valve;VSA = ventricular septal aneurysm.

Although anatomic closure of a ventricular septaldefect is not assured by the formation of a septalaneurysm, natural history studies of these aneurysmssuggest that they are usually associated with a benignasymptomatic course and left-to-right (Qp/Qs) shuntsof less than 2.0.1 7

Our series includes only those patients who were

FIGURE 4. Systolic, stop-frame image of the heart in the long axis. Note the ventricular outflow tract. Theaneurysm originates from the membranous interventricular septum just below the aortic root. Ao = aorta,LA = left atrium; LV = left ventricle; MV = mitral valve; R V right ventricle; Sept = septum;VSA= ventricular septal aneurysm.

923

A

by guest on May 24, 2018

http://circ.ahajournals.org/D

ownloaded from

VOL 59, No 5, MAY 1979

FIGURE 5. Systolic, stop-frame image of the heart in the apicalfour-chamber view. The ventricular septalaneurysm appears as a conical projection of the ventricular septum toward the right ventricle in systole.LA = left atrium; LV= left ventricle; MV = mitral valve; PV pulmonary veins; RA right atrium;RV = right ventricle; TV = tricuspid valve; VSA = ventricular septal aneurysm.

catheterized and, therefore, more likely to havehemodynamically significant left-to-right shunts. Fourof the nine patients with ventricular septal defect andventricular septal aneurysm had several associatedcardiac lesions (table 1). Of the five patients withisolated ventricular septal defect and ventricular sep-tal aneurysm, only one patient (DW) had significantlyelevated pulmonary artery pressures. This child alsohad Down's Syndrome, which may have contributedto the elevated pulmonary artery pressure. Two of thefive patients with isolated ventricular septal defect hadevidence on serial cardiac catheterization of decreas-ing ventricular shunt size and decreasing pulmonaryartery pressures accompanied by septal aneurysm for-mation. Complete closure of a ventricular septaldefect by septal aneurysm formation was not observedin our patients. Therefore, we do not know theechocardiographic appearance of the ventricular sep-tal aneurysm once complete closure has occurred. Theechocardiographic appearance of the ventricular sep-tal aneurysm in older children (DD, TW) with nearcomplete closure of the ventricular septal defect wassimilar to that of the younger children in the series.

Echocardiography can be an accurate noninvasivemethod of detecting ventricular septal aneurysms.Assad-Morell and colleagues reported a largeaneurysm of the membranous interventricular septumdetected by M-mode echocardiography.16 Sapire andBlack reported a series of seven aneurysms of themembranous ventricular septum that were detected byM-mode echocardiography.'6 In their series echocar-diography was 100% accurate, neither missing norerroneously diagnosing a single case. We believe thatthis important early work was too optimistic in es-timating the sensitivity of M-mode echocardiographyas a diagnostic tool in the detection of ventricular sep-

tal aneurysms. The previously published echocar-diograms of Sapire and Black'6 and our own examples(figs. 2 and 3) show that there could be several pitfallsto accurate interpretation. Lateral resolution errorsintroduced by the M-mode beam width could easilylead to misinterpretation of echoes from the aorticroot, tricuspid valve apparatus or the septum itself, fortrue septal aneurysms. In our experience the most con-sistent M-mode finding of a ventricular septalaneurysm is the presence of coarse fluttering echoeswith abrupt systolic anterior motion anterior to thetricuspid valve echo. However, we have observed theseM-mode patterns in four patients who did not have aventricular septal aneurysm. In these patients, thesystolic motion of the aortic root or chordae tendinaemimicked septal aneurysms; however, the charac-teristic coarse flutter was not noted. These errors maybe minimized if a careful right ventricular outflowtract sweep is performed, because the bulging septalaneurysm is most easily separated from the tricuspidvalve in the region of the right ventricular outflowtract. We have also found that an expanded view, as il-lustrated by figure 3, and rapid paper speed are helpfulin differentiating systolic tricuspid valve from thebulging systolic septal aneurysm. A 3.5 MHz non-focused transducer is of further help in accuratelydelineating these anterior structures. Although the M-mode echocardiogram may misdiagnose ventricularseptal aneurysms, it is nonetheless a useful screeningtechnique for their detection.

Two-dimensional echocardiography, because of itsreal-time format and spatial anatomic display,provides an even more complete noninvasive means ofdetecting ventricular septal aneurysms. We found two-dimensional echocardiography to be a sensitivetechnique, enabling us to detect all patients with a ven-

924 CIRCULATION

I

by guest on May 24, 2018

http://circ.ahajournals.org/D

ownloaded from

ECHO EVALUATION OF SEPTAL ANEURYSMS/Snider et al.

FIGURE 6. Systolic, stop-frame image of the heart in the apicalfour-chamber view from a patient with apartial endocardial cushion defect and tricuspid pouch. The tricuspid pouch has an appearance in-distinguishable from a ventricular septal aneurysm. ASD 1° - primum atrial septal defect; LA - leftatrium; LV = left ventricle; RA = right atrium; RV = right ventricle.

tricular septal aneurysm found at cardiac catheteriza-tion. We have observed the systolic bulging of the sep-tum in all cases of proven ventricular septalaneurysms.We believe, for maximum diagnostic accuracy,

multiple two-dimensional echocardiographic viewsmust be used. The thinness and rapid motion of theseptal aneurysms and overall cardiac motion maycause a single view to miss the aneurysm. We havefound the short-axis and apical four-chamber views tobe the most helpful in visualizing the area of the mem-branous septum. Careful cranial transducer angula-tion from the long-axis and apical views will allow thebest identification of the membraneous septum. Thelocation of the aneurysm and the dynamic nature of itsbulging into the right ventricle during systole can beappreciated with this technique.The specificity of two-dimensional echocardiog-

raphy is difficult to assess from our series. A potentialsource of error we have encountered is the raretricuspid pouch lesion.17 Tricuspid pouches in associa-tion with partial endocardial cushion defects mayproduce a pattern of septal motion indistinguishableon M-mode and two-dimensional echocardiographyfrom membranous septal aneurysms. These pouches,however, can usually be distinguished from septalaneurysms associated with simple ventricular septaldefects by virtue of the associated findings of endo-cardial cushion defect.'8 19 Figure 6 illustrates atricuspid valve pouch found in a patient with partialendocardial cushion defect.With the addition of two-dimensional echocardiog-

raphy to supplement M-mode techniques, thediagnosis of ventricular septal aneurysms can be ac-complished noninvasively, eliminating the need forrepeated invasive studies. This technique should bevaluable not only in the assessment of the individual

patient with ventricular septal defect, but also in thelongitudinal study of this defect.

AcknowledgmentsThe authors gratefully acknowledge the critical review of Dr.

Catherine Covey in preparing this manuscript and the secretarialassistance of Ms. Mary Hurtado.

References1. Freedom RM, White RD, Pieroni DR, Varghese PJ, Krovetz

LJ, Rowe RD: The natural history of the so-called aneurysm ofthe membranous ventricular septum in childhood. Circulation49: 375, 1974

2. Hoffman JIE, Rudolph AM: The natural history of ventricularseptal defects in infancy. Am J Cardiol 16: 634, 1965

3. Lambert ME, Widlansky S, Frankin EA, Hurwitz R, NielsonR, Nasser WK: Natural history of ventricular septal defectsassociated with ventricular septal aneurysms. Am Heart J 88:566, 1974

4. Bloomfield K: The natural history of ventricular septal defectsin patients surviving infancy. Circulation 29: 914, 1964

5. Varghese PJ, Rowe RD: Spontaneous closure of ventricularseptal defects by aneurysmal formation of the membranous sep-tum. J Pediatr 75: 700, 1969

6. Miora KP, Hildner FJ, Cohen LS, Narula OS, Samet P:Aneurysm of the membranous ventricular septum: amechanism for spontaneous closure of the ventricular defect. NEngl J Med 283: 58, 1970

7. Nugent EW, Freedom RM, Rowe RD, Wagner HR, Rees JK:Aneurysm of the membranous septum in ventricular septaldefect. Circulation 56 (suppl I): 1-82, 1977

8. Baron MG, Wolf BS, Grishman A, Van Mierop LHS:Aneurysm of the membranous septum. Am J Roentgenol 91:1303, 1964

9. Cornell SH, Durnin RD: Aneurysm of the membranous inter-ventricular septum. Radiology 91: 915, 1968

10. Feigenbaum H: Echocardiography, 2nd ed. Philadelphia, Leaand Febiger, 1976, pp 55-85

11. Maron BJ, Henry WL, Griffith JM, Freedom RM, Kelley DT,Epstein SE: Identification of congenital malformation of thegreat arteries in infants by real-time two-dimensional echocar-diography. Circulation 52: 671, 1975

12. Silverman NH, Schiller NB: Apex echocardiography: a two-

925

by guest on May 24, 2018

http://circ.ahajournals.org/D

ownloaded from

VOL 59, No 5, MAY 1979

dimensional technique for evaluating congenital heart disease.Circulation 57: 503, 1978

13. Rudolph AM: Congenital diseases of the heart. Chicago, YearBook Medical Publishers, Inc, 1974, p 218

14. Varghese PJ, Izukawa T, Celermajer J, Simon A, Rowe RD:Aneurysm of the membranous ventricular septum: a method ofspontaneous closure of small ventricular septal defects. Am JCardiol 24: 531, 1969

15. Assad-Morell JL, Tajik AJ, Giuliani ER: Aneurysm of mem-branous interventricular septum, echocardiographic features.Mayo Clin Proc 49: 164, 1974

16. Sapire DW, Black IFS: Echocardiographic detection ofaneurysms of the interventricular septum associated with ven-tricular septal defect. Am J Cardiol 36: 797, 1975

17. Kudo T, Yokoyama M, Ionai Y, Konno S, Sakakibara S: Thetricuspid pouch in endocardial cushion defect. Am Heart J 87:544, 1974

18. Williams RG, Rudd M: Echocardiographic features of en-docardial cushion defects. Circulation 49: 418, 1974

19. Pieroni DR, Homcey E, Freedom RM: Echocardiography inatrioventricular canal defect: a clinical spectrum. Am J Cardiol35: 54, 1975

Effects of Nitroglycerin on Echocardiographic Measurementsof Left Ventricular Wall Thickness and Regional Myocardial

Performance During Acute Coronary IschemiaR. ROGER KOMER, M.D., AMY EDALJI, M.D., AND WILLIAM B. HOOD, JR., M.D.

SUMMARY The effects of nitroglycerin on regional left ventricular performance, assessed by echocardio-graphic techniques, were investigated in anesthetized, open-chest dogs during acute myocardial ischemia. Dur-ing transient occlusion of the left anterior descending coronary artery, there was end-diastolic thinning andmarked reduction in systolic thickening in the central ischemic zone. Similar changes of lesser degree werenoted in the border zone. The normal zone was unaffected. Infusion of nitroglycerin during ischemia in dosagesof 2.5-50 ,ug/kg/min reduced left ventricular end-diastolic pressure without changing the abnormalities ofsystolic wall thickening. Effects of bolus injections of 20 and 50 ,ag/kg of nitroglycerin were similar, althoughthis also lowered aortic pressure. In a subgroup of animals in which nitroglycerin infusion was unaccompaniedby tachycardia, there was also no evidence that ischemic dysfunction was altered. We conclude that nitro-glycerin does not improve regional myocardial performance in acutely ischemic canine myocardium. Thedecrease in preload is probably entirely due to the peripheral effects of the agent.

NITROGLYCERIN HAS BEEN USED in thetreatment of angina pectoris for longer than a century.Recently, however, many clinical and experimentalstudies have suggested that the agent may be beneficialin the treatment of left ventricular failure due to bothacute myocardial infarction1-8 and chronic ischemicheart disease.9"'5 These studies have shown thatnitroglycerin causes a reduction in left ventricular fill-ing pressure, a decline in arterial pressure of varyingdegree (depending on route and speed of drug ad-ministration), variable changes in cardiac output, andin many of the studies, evidence of improved perfor-mance of areas of ischemic left ventricular dysfunc-tion. The mechanism for these changes is not known,but has been attributed to increased venous

From the Cardiology Department, Thorndike MemorialLaboratory, and the Department of Medicine, Boston CityHospital, Boston University School of Medicine, Boston,Massachusetts.

Supported by USPHS grants NOI HV 53001, HL 14646, and HL18318.Address for reprints: William B. Hood, Jr., M.D., Cardiology

Department, Boston City Hospital, Boston, Massachusetts 02118.Received October 7, 1977; revision accepted June 22, 1978.Circulation 59, No. 5, 1979.

capacitance, afterload reduction and favorable effectson myocardial oxygen supply/demand ratio.Our study was designed to test whether nitro-

glycerin directly affects segmental myocardial perfor-mance in a canine myocardial ischemia preparation.Performance was assessed by examining left ventric-ular systolic and diastolic wall thickness using ultra-sound techniques during transient occlusion of the leftanterior descending coronary artery. The results showthat ischemic segment dysfunction is not affected bynitroglycerin, and suggest that improved overall leftventricular performance in this preparation is theresult of the peripheral vascular effects of the agent.

Materials and MethodsThe study was performed using 24 mongrel dogs

weighing 21.5 ± 0.9 kg (SEM). The animals wereanesthetized with a mixture of chloralose 30 mg/kgand urethane 450 mg/kg intravenously, afterpremedication with morphine sulphate 3 mg/kg givensubcutaneously. One hour later, a second dose ofmorphine (1.5 mg/kg) was injected subcutaneously.The animals were ventilated using a 40% oxygen-airmixture through a Bennett respirator. A #9 NIHcatheter was introduced through the femoral arteryinto the ascending aorta for continuous measurement

926 CIRCULATION

by guest on May 24, 2018

http://circ.ahajournals.org/D

ownloaded from

A R Snider, N H Silverman, N B Schiller and T A PortsEchocardiographic evaluation of ventricular septal aneurysms.

Print ISSN: 0009-7322. Online ISSN: 1524-4539 Copyright © 1979 American Heart Association, Inc. All rights reserved.

is published by the American Heart Association, 7272 Greenville Avenue, Dallas, TX 75231Circulation doi: 10.1161/01.CIR.59.5.920

1979;59:920-926Circulation. 

http://circ.ahajournals.org/content/59/5/920the World Wide Web at:

The online version of this article, along with updated information and services, is located on

  http://circ.ahajournals.org//subscriptions/

is online at: Circulation Information about subscribing to Subscriptions: 

http://www.lww.com/reprints Information about reprints can be found online at: Reprints:

  document. Permissions and Rights Question and Answer information about this process is available in the

located, click Request Permissions in the middle column of the Web page under Services. FurtherEditorial Office. Once the online version of the published article for which permission is being requested is

can be obtained via RightsLink, a service of the Copyright Clearance Center, not theCirculationpublished in Requests for permissions to reproduce figures, tables, or portions of articles originallyPermissions:

by guest on May 24, 2018

http://circ.ahajournals.org/D

ownloaded from