Quantitative Echocardiographic Features of ARVCD

RV dilatation is a common finding in individuals with ARVC/D [2,4,5]. The echocardiographic study from the North American ARVC/D Registry provided potential quantitative parameters to differentiate probands from matched controls [3]. Table 14.2 shows the mean RV dimensions at end-systole and end-diastole in probands and matched controls. An enlarged right ventricular outflow tract (RVOT) was found in 100% of probands. RVOT long axis dimension of >30mm had a sensitivity of 89% and specificity of 84% for ARVC/D. Since there have been no large population studies on normal RV dimensions with normalization for gender or body size, determining appropriate cut off values for mild or moderate enlargement in order to apply the Task Force criteria remains challenging. Based on the preliminary data available from the North American ARVC/D registry patients, an RVOT dimension greater than 2 and less than 3 standard deviations above the mean value in the control subjects should be considered mildly enlarged.

Highly trained athletes can present an important diagnostic challenge when considering the diagnosis of ARVC/D. RV enlargement has been described as an adaptation to endurance sports [6]. However, ARVC/D with RV enlargement has been associated with ventricular arrhythmias and sudden death in athletes, particularly from the Veneto region of Italy

Imaging Arvc With Echocardiography

Fig. 14.1 • Echocardiography views from probands meeting Task Force criteria for ARVC/D.(a) RVOT enlargement from the parasternal long axis view,(b) RVOT enlargement from the parasternal short axis view, (c) Apical four-chamber view showing a focal RV apical aneurysm (arrows), (d) Apical four-chamber view showing excessive trabeculations (arrows). (e) Apical four-chamber view showing a hyperreactive moderator band (arrow). LV, left ventricle; RV, right ventricle; RVOT, right ventricular outflow tract; AoV, aortic valve; RA, right atrium; LA, left atrium. Reprinted from [3], © 2005, with permission from the American College of Cardiology Foundation

[7, 8]. A careful medical and family history, as well as application of the Task Force diagnostic criteria exclusive of RV structure and function, may help distinguish normal adaptation from disease. In the future, novel echocardiographic parameters such as tissue Doppler and strain imaging may help better refine diagnostic utility of echocardiography in this situation.

Global RV dysfunction is also often noted in individuals with ARVC/D. Because of the geometry of the RV and problems with complete RV visualization in some individuals, estimation of RV volume by echo is challenging, thus making accurate estimation of an RV ejection fraction difficult. The RV fractional area change (FAC) from the parasternal long axis view has been shown to be a useful correlate of RV function [9], and is increased in individuals with ARVC/D compared with controls [3]. Table 14.3 shows the mean values for RV FAC in probands compared with controls from the North

Arvc Echo Images

Table 14.1 • Frequency of qualitative echocardiography abnormalities in individuals with ARVD (n=29)

Number Percent

Table 14.1 • Frequency of qualitative echocardiography abnormalities in individuals with ARVD (n=29)

RV global function:

Normal

11

38

Mildly reduced

8

28

Severely reduced

10

34

RV Regional WMA

23

79

RVOT

13

45

Anteroseptal

16

55

Anterior

20

70

Apex

21

72

Septal

16

55

Inferior Basal

17

59

Inferior Apical

15

52

Hyperreflective moderator band

9

31

Excessive/abnormal trabeculations

15

54

Sacculations

5

17

RV,right ventricular; RVOT,right ventricular outflow tract; WMA, wall motion abnormality.Reprinted from [3],© 2005,with permission from the American College of Cardiology Foundation

Table 14.2 • Quantitative echocardiography abnormalities

Right heart dimensions

ARVC/D probands (mean±SD)

Matched controls (mean±SD)

P-value

Reference values (mean±SD)

% of probands enlarged

RA medial-lateral (mm)

44.8±11.4

36.6±6.9

0.0035

37±4

41%

RA superior-inferior (mm)

51.3±10.6

45.7±5.8

0.023

42±4

45%

RVOT-PLAX diastole (mm)

37.9±6.6

26.2±4.9

0.00001

22±1.5

100%

RVOT-PLAX systole (mm)

32.8±7.2

20.1±4.0

0.00001

NA

RVOT-PSAX diastole (mm)

38.9±4.7

31.1±4.7

0.00001

27±1

96%

RVOT-PSAX systole (mm)

28.3±6.1

19.0±5.1

0.00001

NA

RVOT/aortic valve

1.28±0.2

1.04±0.2

0.0001

NA

RVIT PLAX diastole (mm)

57.0±12.2

49.2±8.8

0.0065

45±2.5

73%

RVIT PLAX systole (mm)

46.5±12.6

34.2±6.8

0.0001

NA

RVIT PSAX diastole (mm)

37.3±8.5

28.1±5.2

0.0004

30±1.5

60%

RVIT PSAX systole (mm)

32.3±8.5

21.6±5.6

0.0004

NA

RV medial-lateral -Apical 4 Chamber diastole (mm)

34.0±8.9

25.1±4.0

0.00001

30±5

18%

RV medial-lateral -Apical 4 Chamber systole (mm)

27.26± 9.8

17.6±3.9

0.00001

24±3

36%

RV LAX length -Apical 4 chamber diastole (mm)

79.2± 15.6

76.1 ±7.6

0.2281

71±8

24%

RV LAX length -Apical 4 chamber systole (mm)

66.7±15.8

61.2±6.0

0.0802

55±8

38%

LAX, long axis; NA, not available; PLAX, parasternal long axis; PSAX, parasternal short axis; RA, right atrial; RV, right ventricular; RVIT, right ventricular inflow tract; RVOT, right ventricular outflow tract; SD, standard deviation. Reprinted from [3],© 2005,with permission from the American College of Cardiology Foundation

ARVC/D probands (mean±SD)

Matched controls (mean±SD)

P-value

Reference value

RV end diastolic area (cm2)

25.2±7.7

17.9±3.5

0.00001

19.5±4.3

RV end systolic area cm2)

18.9±8.4

10.5±2.3

0.00001

10.5±3.0

RV FAC (%)

27.2±16

41.0±7.1

0.0003

46.5±7.1

Percent with FAC >32

35%

97%

Percent with FAC 26%-32%

24%

3%

(mildly impaired)

Percent with FAC <26

41%

0%

(severely impaired)

FAC, fractional area change; RV, right ventricular;SD, standard deviation. Reprinted from [3],© 2005, with permission from the American College of Cardiology Foundation

American ARVC/D Registry. In this study, RV FAC was measured from the apical four-chamber view. An RV FAC <32% was present in 65% of probands and only 3% of matched controls. As mentioned previously for RV enlargement, there have been no large population studies on normal values for RV FAC with normalization for gender or body size. Thus, determining appropriate cut off values for mild or moderate RV dysfunction in order to apply the Task Force criteria remains challenging.

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