GUEST LECTURE IN FULL

ULTRASOUND STETHOSCOPY

J.R.T.C. Roelandt*, MD, FACC, Chairman Department of Cardiology, Thoraxcentre, Erasmus MC, Rotterdam, The Netherlands

Echocardiography is currently the most widely used and cost-effective diagnostic imaging tool in cardiology. Since it is often the best or even the only applicable method, it has largely supplanted other imaging modalities in a wide variety of health care environments. Miniaturization and digital techniques recently resulted in the development of high resolution battery-powered personal ultrasound imaging devices with excellent grey-scale and color blood flow imaging capabilities.
 These personal imagers are appropriately named "ultrasound stethoscopes" since they make it possible to look into the chest (stethos=chest and skopein=see) and see the heart and its pathology during physical examination.
 They can be used anytime anywhere just like a conventional stethoscope.
1 We will discuss the potential of these small ultrasound imaging devices in different clinical scenarios and how they may extend the physical examination and the practice of cardiology.

       ULTRASOUND STETHOSCOPES

       CLINICAL USES

       DISCUSSION
       References

ULTRASOUND STETHOSCOPES

Two small hand-held ultrasound imagers have recently been introduced (SonoHeartTM, SonoSite, Inc. Bothell, WA, USA and OptiGoTM, Agilent Technologies, Andover, MA, U.S.A.) (fig 1). They are based on miniaturized digital technology and make use of phased array transducers providing high-resolution two-dimensional dynamic grey-scale tissue imaging combined with color Doppler flow imaging (directional for the SonoHeartTM). 
The upgraded SonoHeart PlusTM device features second harmonic imaging and has integrated M-mode and pulsed-wave Doppler capabilities as well as an electrocardiographic reference lead.
 The devices operate on a rechargeable battery or AC current and have measurement packages including linear measurement callipers. The internal memory of the SonoHeartTM allows storage up to 120 images, which can be downloaded into a PC and there is a video output, which can be connected to a monitor or to a VCR for permanent recording. 
The OptiGoTM allows images to be documented on a CompactFlash card. Other companies are also developing miniaturised ultrasound imaging systems. 
The TerasonTM device (Teratech Corp, Burlington, MA, USA) has the micro-miniaturised ultrasound system incorporated in the transducer and connects to a notebook PC (fig 1). The small ultrasound devices should not be confused with the portable desktop systems which are full featured systems.

Figure 1

Figure 1. Photographs of the (A) MinivisorTM developed in 1978.32-34 and currently available hand-held ultrasound devices (B) OptiGoTM, (C) SonoHeartTM and (D) TerasonTM.

The examination procedure with these devices is the same as with standard echocardiography and all precordial windows can be used for structure and blood flow imaging. Our experience with the SonoHeartTM and OptiGoTM device indicates that morphologic data obtained in standard cardiac views and basic linear measurements of structures and cavities adequately compare with those documented with standard equipment.2

CLINICAL USES

The physical examination remains the cornerstone of the initial evaluation of a patient with suspected cardiovascular disease. However, notable shortcomings in examination skills and more particularly in auscultation have been documented even after training with innovative instructional methods.3-6 In addition, over the years, echo/Doppler studies have brought out the limitations of the physical examination in many cardiac conditions, particularly in the early stages of disease and no quantitative information is obtained.7 “Visualising the heart” with the ultrasound stethoscope as part of the physical examination provides additional information beyond what we can perceive with palpation and auscultation and permits rapid confirmation of a cardiac abnormality (valve disease, shunt (fig 2), cavity dilatation, hypertrophy, pericardial effusion, wall motion abnormality) and a specific diagnosis in any clinical setting can be made (table 1 and fig 3).

Incidental findings are also regularly recognized.8,9 The routine physical cardiac examination can be extended by imaging and by obtaining limited quantitative measurements of the inferior vena cava, liver, spleen and abdominal aorta. The loss of inspiration narrowing of the inferior vena cava is a reliable and sensitive marker of elevated central venous pressure and right heart failure (fig 4).10 The major strength of a limited echo/Doppler examination is its specificity that allows exclusion of a cardiac abnormality with great certainty after limited training. However, it is crucial to have sensitive color flow imaging capabilities. Standard echocardiography involves a comprehensive examination with complex equipment by an operator with considerable training and experience. However, the diagnosis

Figure 2

TABLE 1. THE ULTRASOUND STETHOSCOPE

Figure 3

Figure 4

and follow-up of many cardiac conditions requires only a fraction of the potential of these expensive facilities and a specific clinical question can often be answered within little time and with little examination protocols. 9,11-13 The ultrasound stethoscope is very suitable for such a “focussed” or “goal-oriented” examination.
 The resolution of a pericardial effusion after a pericardiocentesis (fig 5), cardiac dimensions and left ventricular (LV) function both of which are important parameters in the follow-up of many patients are rapidly assessed at the bedside (agreement for semi-quantitative LV size assessment between standard echocardiography and SonoHeartTM in 111 consecutive patients was 99%; kappa value 0.970 and for ejection fraction 93%; kappa value 0.871)1.
 Patients with hypertension and LV hypertrophy have an increased risk of a cardiovascular event and the success or failure of their antihypertensive treatment can be assessed by wall thickness measurements (figure 6).9,12,14 “Goal-oriented” echocardiography will undoubtedly become part of the initial physical examination by primary care physicians to identify or exclude a cardiac condition who will use telecommunication technology for consultation in the future.
15 The ultrasound stethoscope can effectively

Figure 5

Figure 6

assist in the initial evaluation and rapid diagnosis of potentially life threatening conditions in the intensive care environment or in situations where quick-decision making is essential. In many such situations standard echocardiography is not rapidly available. 
The ultrasound stethoscope carried by the attending cardiologist provides data inaccessible by clinical examination and allows immediate diagnosis or exclusion of emergent tamponade, a dilated heart, and valvular pathology (e.g. calcific aortic stenosis in low output state) (fig7 and 8). Pericardiocentesis can be guided and the effects of acute interventions (e.g. fluid challenge n hemodynamically compromised patients, inotropic drugs) monitored through estimation of cavity dimensions, ejection fraction and wall dynamics (fig 9). In a recent study by Goodkin et al16, the potential of a hand-held device to rapidly obtain important clinical information during the physical examination in critically ill patients was demonstrated. However, proper management of these patients often requires hemodynamic data which are obtained with standard equipment. 

Immediate echocardiographic assessment in the emergency room has been reported to considerably shorten the time to diagnosis of penetrating cardiac injury and to improve the chances of survival.17-20 Right ventricular involvement in acute myocardial infarction and the mechanical complications of a myocardial infarction are readily diagnosed in the coronary care unit.
 Echocardiography of the right heart is of great value in patients with acute pulmonary embolism.21 The demonstration of right ventricular dilatation and paradoxical septal motion in patients clinically suspected raises the level of suspicion significantly while their absence does not exclude pulmonary embolism. On the other hand, many conditions that clinically mimic pulmonary embolism are rapidly identified.22 Regional wall function abnormalities are reliably detected (90% agreement in 204 segments of 34 patients), a potential which can be utilized in chest pain clinics for rapid screening in the context of acute chest pain and a non-diagnostic electrocardiogram in chest pain clinics.3 The ultrasound stethoscope could be used for

Figure 7

Figure 8

screening and identifying unexpected cardiac disorders with a low prevalence in a specific population. However, the sensitivity of these devices for identifying certain conditions is still to be defined and the competence and training level of the examiner is an important aspect to consider. The feasibility of community screening for asymptomatic LV dysfunction has been demonstrated.23 The ultrasound stethoscope allows rapid screening for an occult aortic abnominal aneurysm in patient groups “at risk” (patients with coronary artery disease, hypertension, elderly) (fig 10).24-26 Physical examination is notably insensitive in moderately enlarged aneurysmata and obese patients. Aortic diameter measurements compared well to those obtained with standard equipment (agreement 97% in 100 consecutive patients; kappa value 0.810) and are obtained in a few minutes during a routine physical examination.

Figure 9

Figure 10

Figure 11

Limited echocardiography allows to screen for left ventricular hypertrophy (agreement with standard echocardiography in 100 consecutive patients 92%, kappa value 0.730) and to follow the effect of treatment in office practice.12 Mitral valve prolapse is often suspected in otherwise asymptomatic individuals. This disorder can be excluded or confirmed in a limited number of standard views (figure 11).27 Potentially dangerous conditions can be identified in preparticipation screening of athletes. Hypertrophic cardiomyopathy, a dilated ascending aorta (Marfan) (figure 12) and valvular abnormalities (bicuspid valve, mitral valve prolapse) are the most common disorders and are reliably detected by experienced examiners.24-28 However, screening for cardiac disorders in young athletes and asymptomatic individuals involves a high risk of a false positive diagnosis.

Figure 12

DISCUSSION

In 1904, W. Rollins described the “Seehear”, a device combining a fluoroscope with a standard stethoscope extending the clinical perception of the auscultation with seeing. Clearly, ultrasound offers obvious advantages over x-rays. We developed and used an ultrasound stethoscope (MinivisorTM, Organon Teknica) as early as 1978.29-32 and in 1988, a hand-held sector scanner (ScanMateTM, Damon Corp) was introduced by the Rochester group.30,31 However limited imaging performance and reimbursement issues did not stir the enthusiasm of cardiologists who were confronted in those days with the rapidly expanding capabilities and applications of the high-end ultrasound systems. 
Now, technology allows to construct small personal imaging systems with excellent structure and blood flow imaging. Expanding our routine physical examination with a small personal imager will significantly strengthen our diagnostic capabilities (table 2) On the basis of normal structure and functional findings in the absence of blood flow turbulence, all of which can be tested in a limited number of imaging views, a cardiac disorder can be excluded with a high degree of certainty.
 This high negative predictive value is ideal for rapid screening to avoid referral of normals and for a more cost-effective use of our expensive diagnostic imaging facilities. 
Personal imagers will therefore have an impact not only on the physical examination but also on

TABLE 2. The ultrasound stethoscope Seeing the invisible during the physical examination provides:

the use of echocardiography and other imaging modalities by targeted referral. A major application will become its use in a critical care environment. 
Direct diagnosis or exclusion of some life-threatening conditions will shorten delays in proper management and therapy and lead to important cost-savings.
 These devices are extremely suited for a limited “focussed” ultrasound examination to follow the course of a disease or to test the effect of therapy in the outpatient clinic in office practice. Obviously, a small ultrasound imager must be used as an adjunct of the physical examination and cannot substitute for the high-end ultrasound systems.
15 Therefore, its use involves some compromises which will be learned when applications are expanding. Training of non-echocardiographers may become an important issue and should focus on criteria of normalcy and identifying both major and acute cardiac disorders. In fact, the device should be used in a way comparable to auscultation; whenever there is doubt, further echo/Doppler is examination is indicated. Training programs and continuing medical education including performance testing can be organized with modern electronic means.
n the future, advances in communications and software will allow for diagnostic support from experienced laboratories or intensive care units. It should be remembered that the real value of any imaging technology is intimately dependent on our intellectual contribution: how, when and what clinical scenario it will have its optimal clinical impact.

References

1.   Roelandt JRTC. A personal ultrasound imager (ultrasound stethoscopy). 
      A revolution in the physical cardiac diagnosis! Eur Heart J 2001;in press.

2.   Vourvouri EC, Poldermans D, De Sutter J, et al. 
      Experience with an ultrasound stethoscope. 
      J Am Soc Echocardiogr, 2001;14:in press.

3.   Hu BS, Altiel F, Popp RL. 
      Effectiveness of limited training in echocardiography for cardiovascular diagnosis.
      Circulation 1996;94 (suppl):I 253.

4.   Mangione S, Nieman LZ. Cardiac auscultatory skills of internal medicine and family 
      practice trainees. A comparison of diagnostic proficiency. JAMA 1997;278:717-22.

5.   St. Clair EW, Oddone EZ, Waugh RA, et al. Assessing housestaff diagnostic skills
      using a cardiology patient simulator. Ann Int Med 1992;117:751-6.

6.   Spencer KT, Anderson AS, Bhargava A, et al.
      Physician- performed point-of-care echocardiography using a laptop platform
      compared with physical examination in the cardiovascular patients.
      J Am Coll Cardiol 2001;37:2013- 8.

7.   Popp RL. The physical examination of the future: 
      echocardiography as part of the assessment. ACC Current Rev 1998;7:79-81.

8.   Bossone E, Marcovitz P, Bach DS. Occult cardiac abnormalities are 
      not uncommon  in critically ill patients:
      echocardiographic evaluation of 467 consecutive patients admitted to 
      a medical intensive care. J Am Coll Cardiol 1997;29:438A.

9.   Kimura BJ, Pezeshki B, Frack SA, DeMaria AN. Feasibility of “limited” echo imaging:
      characterization of incidental findings.
      J Am Soc Echocardiogr 1998:11;746- 50.

10.   Kircher BJ, Schiller NB, Himelman MB.
        Noninvasive estimation of right atrial pressure from the inspiration collapse 
        of the inferior vena cava.
        Am J Cardiol 1990;66:493-6.

11.   Black HR, Weltin G, Jaffe CC. The limited echocardiogram:
        a modification of standard echocardiography for use in the routine evaluation 
        of patients with systemic hypertension. 
        Am J Cardiol 1991;67:1027-30.

12.   Sheps SG, Frohlich ED. Limited echocardiography for hypertensive left 
        ventricular hypertrophy. 
        Hypertension 1997;29:560-3.

13.   Vourvouri EC, Poldermans D, Schinkel AFL, Koroleva L, Sozzi FB, Bax JJ, 
        Roelandt JRTC. Left ventricular hypertrophy screening using a hand-held
        ultrasound device (Eur Heart J 2001, submitted).

14.   De Simone G, Devereux RB, Ganau A, et al. Estimation of left ventricular 
        chamber and stroke volume by limited M-mode echocardiography and 
        validation by two- dimensional and Doppler echocardiography. 
        Am J Cardiol 1996;78:801-7.

15.  Pezeshki B, Blanchard DG, Kimura BJ. Can a brief, single-view “screening” 
       echo detect significant echo findings?
       Implications regarding telemedicine  evaluation.
       Circulation 1998;98:I-844.

16.   Goodkin GM, Spevack DM, Tunick PA, Kronzon I. How useful is 
        hand-carried bedside echocardiography in critically ill patients?
        J Am Coll Cardiol 2001;37:2019- 22.

17.  Rozycki GS, Pchsner G, Schmidt JA, et al.
       A prospective study of surgeon-performed ultrasound as the primary adjuvant
       modality for injured patient assessment.
       J Trauma 1995;39:492-500.

18.   Rozycki GS, Pchsner G, Schmidt JA, et al. A prospective study 
        of surgeon-performed ultrasound as the primary adjuvant modality for 
        injured patient assessment. 
        J Trauma 1995;39:492-500.

19.   Rozycki GS, Feliciano DV, Schmidt JA, Cushman JG, Sisley AC,
        Ingram W, Ansley JD.
        The role of surgeon- performed ultrasound in patients with possible cardiac 
        wounds.
        Ann Surg 1996;223:737-46.

20.   Rugolotto M, Liang DH, Hu BS, Chang CP, Schnittger I. 
        Bedside point-of-care echocardiography performed with a new generation
        hand-carried device: impact on the management of patients hospitalized
        for acute cardiac care. 
        Eur Heart J 2001; 22 (suppl):S 707.

21.   JACC/AHA guidelines for the clinical application of echocardiography:
        executive summary.
        J Am Coll Cardiol 1997;29:862-79.

22.   Ribeiro A. The role of echocardiography Doppler in pulmonary embolism.
        Echocardiography 1998;15:769- 77.

23.   Lahiri A, Galasko GIW, Senior R. Portable echocardiography- 
        and innovative tool in the assessment of left ventricular dysfunction 
        in the community. 
        Eur Heart J 2001; 22 (suppl):S 706.

24.   Bruce CJ, Spittell PC, Montgomery SC, et al. Personal ultrasound imager:
        abdominal aortic aneurysm screening.
        J Am Soc Echocardiogr 2000;13:674-9.

25.   Vourvouri EC, Poldermans D, Schinkel AF, Sozzi FB, Bax JJ, van Urk H, 
        Roelandt JR.
        Abdominal aortic aneurysm screening using a hand-held ultrasound device,
        A pilot study. Eur J Vasc Endovasc Surg. 2001;22:352-4.

26.   Sianos G, Vourvouri E, Nieman K, Ligthart JM, Thuri A, de Feyter PJ, 
        Serruys PW, Roelandt JR. Aneurysm of the abdominal aorta.
        Circulation 2001;104:E10-1.

27.  Kimura BJ, Scott R, Willis CL, DeMaria AN. Accuracy and cost-effectiveness 
       of single-view echocardiographic screening for suspected mitral valve prolapse.
       Am J Med 2000108:331-3.

28.  Murry PM Cantwell JD, Heath DL, Shoop J.
       The role of limited echocardiography in screening athletes. 
       Am J Cardiol 1995;76:849-50.

29.  Weidenbener EJ. Krauss MD, Waller BF, Taliercio CP. 
       Incorporation of screening echocardiography in the preparticipation exam. 
       Clin J Sport Med 1995;5:86-9.

30.  Maron BJ, Bodison SA, Wesley YE, Tucker E, Green KJ. 
       Results of screening a large group of intercollegiate competitive athletes 
       for cardiovascular disease. 
       J Am Coll Cardiol 1987;10:1214-21.

31.   Ligtvoet CM, Rijsterborgh H, Kappen L, Bom N.
        Real time ultrasound imaging with a hand-held scanner.
        Part I – technical description. Ultrasound Med Biol 1978;4:91- 2.

32.   Roelandt J, Waldimiroff JW, Baars AM. Ultrasounic real time imaging with 
        a hand-held scanner. II: Initial clinical experience. 
        Ultrasound Med Biol 1978;4:93-6.

33.   Roelandt J, Cate FJ ten, Hugenholtz PG, et al. The ultrasonic stethoscope:
        a miniature hand-held device for real time cardiac imaging. 
        Roelandt J, Cate FJ ten, Hugenholtz PG, Bom N, Ligtvoet CM. 
        Circulation 1978;58:II-75.

34.   Roelandt J, Bom N, Hugenholtz PG. 
        The ultrasound cardioscope: a hand-held scanner for real-time cardiac imaging. 
        J Clin Ultrasound 1980;8:221-5.

35.  Schwarz KQ, Meltzer RS. Experience rounding with 
       a hand-held two-dimensional cardiac ultrasound device.
       Am J Cardiol 1988;62:157-9.

36.   Xie F, Breese MS, Nanna M, Lichtenberg GS, Allen MN, Meltzer R.
        Blinded comparison of an “ultrasound stethoscope”
        and standard echocardiographic instrument. 
        Chest 1988;94:270-4.

37.   Sorelli VL, Reeves WC. Noninvasive right and left heart catheterization: 
        taking the echo lab beyond an image- only laboratory. 
        Echocardiography 2001;18:31-41.

The audience, Ritz-Carlton Hotel, Doha, Qatar