Angiographic Features of Wall Structure and Wall Motion in ARVCD

A variety of morphological and structural RV an-giographic features have been reported to be suggestive of ARVC/D. These include global and regional dilatation, dilatation of the outflow tract, localized akinetic or dyskinetic bulges and outpouchings, polycyclic contours ("cauliflower aspect"), and tra-becular hypertrophy and/or disarray with deep horizontal fissures ("pile d'assiettes") as well as dye persistence due to delayed contrast evacuation.

In the first publications on RV angiography in ARVC/D, the diagnostic value of these findings was not validated against normal controls. However, several subsequent studies utilized a more systematic approach, including qualitative and quantitative analyses and a comparison of the results with a normal control group to validate the diagnostic accuracy of RV angiographic findings in ARVC/D [15-17]. However, none of these studies clearly defined mild, moderate, or severe RV dysfunction.

Dye Persistence

Regionally delayed contrast evacuation ("dye persistence") of the RV is a frequent angiographic finding in ARVC/D. However, it also occurs in normal control subjects, particularly in the inferobasal area, and therefore lacks specificity. In such cases, the finding appears to be related to the physiologic asynchronous contraction of the RV wall. Therefore, localized dye persistence should only be considered as a finding indicative for ARVC/D if it occurs in an area of abnormal RV structure or function.

Trabecular Hypertrophy

The diagnostic value of trabecular hypertrophy is also controversial [17] because it is very difficult to define and to distinguish abnormal from normal RV trabeculation.

Transverse orientation of hypertrophic trabeculae separated by deep horizontal fissures create the so-

it called "pile d'assiettes" image that is considered a frequent but not very specific finding mainly located in the anterior and anteroseptal areas (Fig. 16.4). In a study by Daliento et al. [16], this finding was the qualitative variable most significantly associated with ARVC/D, although with a low sensitivity of only 56%.

At the same time, this study confirmed that simple transverse trabecular arrangement was not a useful diagnostic parameter in ARVC/D because it was a nonspecific finding present in 23% of normal controls and also in RV dilatation irrespective of the underlying disease. Similar findings were reported by Daubert et al. [17] in a critical analysis of the angio-graphic criteria in ARVC/D. In this study, trabecular hypertrophy was present in 62% of patients with ARVC/D but also in 30% of normal control subjects.

Probably because of this large variability of normality and the subjective assessment and interpretation, this feature was not included as a diagnostic an-giographic finding in the Task Force criteria for the diagnosis of ARVC/D [11].

However, in the association with trabecular hypertrophy (thickness of >4 mm) and in presence of deep fissures or so-called Y-shaped giant trabeculae, transverse trabecular arrangement is considered to be of much higher diagnostic value (Fig. 16.4). This is particularly true when these angiographic features are located in the apical and supra-apical RV areas where they are considered to reflect abnormal hypertrophy of the papillary muscles and the moderator band, which are more specific and highly suggestive for ARVC/D.

Fig. 16.4 • Right ventricular angiogram (30° RAO view) demonstrating transverse trabecular hypertrophy (arrows) with horizontal fissures ("pile d'assiettes") and "giant tra-becula"(b/'g arrow) in the anteroseptal,apical,and outflow tract areas of the RV in a patient with ARVC/D

Polycyclic Contours

In areas of more severe structural remodeling, multiple sacculations or round opacified areas merge to produce a polycyclic contour of the RV, also described as a "cauliflower" aspect (Figs. 16.5,16.6). This finding is also considered a specific and diagnostic an-giographic feature strongly suggestive of ARVC/D.

Structure Right Ventricle
  1. 16.5 • Regional right ventricular wall motion abnormalities and polycyclic contours in ARVC/D. RV angiography (30° RAO view; left panel) in a patient with ARVC/D demonstrating moderate global RV enlargement and regional wall motion abnormalities with outpouchings and polycyclic contours in the inferior and apical RV.Magnetic resonance imaging (short axis view; right panel) shows focal signal increase of RV myocardium in corresponding areas indicating fatty tissue replacement. Adapted and reproduced from [9] with kind permission of Springer Science and Business Media
  2. 16.5 • Regional right ventricular wall motion abnormalities and polycyclic contours in ARVC/D. RV angiography (30° RAO view; left panel) in a patient with ARVC/D demonstrating moderate global RV enlargement and regional wall motion abnormalities with outpouchings and polycyclic contours in the inferior and apical RV.Magnetic resonance imaging (short axis view; right panel) shows focal signal increase of RV myocardium in corresponding areas indicating fatty tissue replacement. Adapted and reproduced from [9] with kind permission of Springer Science and Business Media
Arvcd Angiogram
Fig. 16.6 • Right ventricular (RV) angiography (30° RAO view, end systole) in a patient with ARVC/D showing polycyclic contours and moderate hypokinesia in the RV outflow tract

However, it is not very sensitive because it mainly occurs in patients with manifestations of more advanced disease.

Regional Hypokinesia

Blomstom-Lundqvist et al. [18] assessed the reproducibility of global and regional angiographic findings within and between observers in patients with

ARVC/D. Poor correlations were found particularly with regard to the motion of the apex and the anterior wall.

This is probably due to the nonuniform contraction of the normal RV which is in contrast to the uniform contraction of the LV. This was clearly demonstrated in the quantitative analysis of regional RV wall motion in normal control subjects published by Indik et al. [19]. The study showed significant differences of wall motion in the various regions of the RV. Inflow tract areas contributed to systolic contraction much more than midanterior and outflow tract areas as measured by the normalized change in total contour area of RV angiograms (Fig. 16.7). Furthermore, the relative timing of contraction was non-homogeneous. Strain as another measure of nonuniform contraction was also found to vary significantly in different locations, thus also reflecting the heterogeneous motion of the RV wall. The same study also demonstrated no differences in RV wall motion between normal control subjects and patients with idiopathic RV outflow tract tachycardia [19].

Therefore, mild hypokinesia in the apical, anterior, or outflow-tract region (Fig. 16.6) is not a pathologic but rather a normal finding of RV wall motion. This wide overlap with normality makes it particularly difficult to differentiate mild forms of localized ARVC/D from normal RV wall motion. Therefore, more detailed quantification of regional RV wall motion is required to evaluate and correctly diagnose such patients.

Normal Wall Motion
  1. 16.7 • Regional systolic right ventricular (RV) wall motion in normal control subjects.The normalized change in total contour area (in %) within each zone indicates the heterogeneous and nonuniform contraction of different RV regions. Mean values (±SEM) are shown within each zone.The tricuspid valve zones (zones 1-3:Sup-TV,Lat-TV,and IL-TV) show the greatest movement during contraction, and the mid-anterior (Mid-Ant, zone 4) and outflow-tract (Mid-AS, zone 7) regions show the least movement. Adapted from [19]
  2. 16.7 • Regional systolic right ventricular (RV) wall motion in normal control subjects.The normalized change in total contour area (in %) within each zone indicates the heterogeneous and nonuniform contraction of different RV regions. Mean values (±SEM) are shown within each zone.The tricuspid valve zones (zones 1-3:Sup-TV,Lat-TV,and IL-TV) show the greatest movement during contraction, and the mid-anterior (Mid-Ant, zone 4) and outflow-tract (Mid-AS, zone 7) regions show the least movement. Adapted from [19]

Tricuspid Annulus Plane Systolic Excursion

RV base-to-apex shortening plays a key role in RV contraction and emptying. Hebert et al. [20] investigated 85 patients with ARVC/D and demonstrated a strong relationship between the tricuspid annulus plane systolic excursion (TAPSE) and RV ejection fraction. The sensitivity and specificity of TAPSE <12 mm in identifying patients with a RV ejection fraction <35% were 96% and 78%, respectively. Decreased TAPSE <12 mm and a diffuse RV outflow tract aneurysm were sensitive and specific indicators of RV ejection fraction <35% and LV ejection fraction <40%, respectively.

Bulgings and Aneurysms

In contrast to regional hypokinesia, localized akinetic or dyskinetic areas, appearing as aneurysms, bulgings, outpouchings, or sacculations (Figs. 16.2, 16.5, 16.8, 16.9), have not been found in normal control subjects and are rare angiographic findings in other diseases affecting the RV. These features, which are mainly located in the "triangle of dysplasia" (Fig. 16.2), are therefore specific and diagnostic for ARVC/D.

In a discriminate analysis, Daliento et al. [16] investigated the diagnostic value of different RV an-giographic features in patients with ARVC/D in comparison to those with dilated cardiomyopathy, atrial septal defect, and normal controls. Apart from transverse-oriented hypertrophic trabeculae, bulgings of the infundibular anterior wall and the subtricuspid (inferobasal) region were the only other independent variables indicative for ARVC/D. Coexistence of these signs was associated with a sensitivity of 88% and a

Fig. 16.8 • Right ventricular (RV) angiogram (30° RAO view) demonstrating a localized RV outflow tract aneurysm as well as inferobasal (subtricuspid) akinesia with mild tricuspid regurgitation in a patient with ARVC/D (arrows)

specificity of 96% for the correct diagnosis of ARVC/D [16] (Table 16.1).

No correlation was demonstrated between histology and specific wall motion abnormalities. In particular, aneurysms were associated with fibrous as well as adipose tissue. However, histological findings may be useful in confirming the diagnosis and assessing the activity of the cardiomyopathic process. In a stable phase of ARVC/D, fibrofatty replacement is the predominant finding, whereas in phases of active disease and progression, histological signs of (sub)acute necrosis, apoptosis, and inflammation, as well as electrical instability may be present [21].

Table 16.1 • Diagnostic accuracy of RV angiography in ARVC/D. Adapted from [16]

ARVC/D (n=32)

DCM (n=27)

ASD (n=28)

Control (n=18)

p-value

EDV-RV (ml/m2)

131

165

141

95

NS

ESV-RV (ml/m2)

62

104

66

38

NS

EF-RV (%)

53

38

54

60

NS

RVOT-diameter (cm)

5

6

5

2

NS

Long axis RV (cm)

12

14

12

5

NS

Dyskinesia RV-apex (%)

41

7

0

0

<0.0001

Dyskinesia RV-inferior (%)

28

7

0

0

<0.0001

Bulging RVOT (%)

75

11

18

11

<0.0001

Bulging inferobasal (%)

91

56

14

5

<0.0001

Tricuspid prolapse (%)

41

7

22

0

<0.001

ARVC/D, arrhythmogenic right ventricular cardiomyopathy/dysplasia; ASD, atrial septal defect; DCM,dilated cardiomyopathy; £DV,end diastolic volume; £F,ejection fraction; £SV,end systolic volume; RV,right ventricle; RVOT,right ventricular outflow tract

ARVC/D, arrhythmogenic right ventricular cardiomyopathy/dysplasia; ASD, atrial septal defect; DCM,dilated cardiomyopathy; £DV,end diastolic volume; £F,ejection fraction; £SV,end systolic volume; RV,right ventricle; RVOT,right ventricular outflow tract

Moderate Tricuspid Regurgitation

Tricuspid Regurgitation

In ARVC/D, tricuspid regurgitation results from two mechanisms: a dilated tricuspid annulus secondary to RV enlargement, and fibrotic involvement of tricus-pid papillary muscles. Therefore, clinically relevant tricuspid regurgitation mainly occurs in patients with advanced stages of ARVC/D (Fig. 16.9).

Left Ventricular Involvement

LV involvement of ARVC/D has been reported to be more frequently present than clinically diagnosed [3,10]. The main findings are localized abnormalities of wall motion (hypokinesia, localized dyskinesia) in the anterior, basal, and apical walls (Fig. 16.10). However, global LV function is rarely affected.

A review of LV cine angiograms performed by the group in Padua [22] showed unusual aspects of parietal motion in at least 60% of cases. LV end diastolic volumes (90±29 ml/m2) and ejection fractions (60±6%) as well as stress/end systolic volume ratios (5.4±2) and mass/volume ratios (0.8±0.1) were normal in a group of patients with ARVC/D less than 20 years old. In an older group (age 38±13 years), only the end diastolic volume was slightly increased (93±36 ml/m2). Statistical analysis showed overlapping of the functional indices in the young and adult groups [22]. However, an increase of dyskinetic areas was observed in the adult group. During a follow-up period of 11.5 years

Fig. 16.9 • Right ventricular (RV) angiogram (30° RAO view, systole) showing global RV enlargement and severe dysfunction in ARVC/D. There is pronounced dilatation of the RV outflow tract, akinesia of the inferior and subtricuspid walls and functional tricuspid regurgitation (grade 2) due to annulus dilatation

Right Ventricular Wall Motion
Fig. 16.10 • Left ventricular (LV) angiogram (30° RAO view, end systole) showing LV involvement with anteroapical akinesia (arrows) in a patient with a long history of progressive ARVC/D and severe global right ventricular enlargement and dysfunction

(range 4 to 17 years), RV and LV angiography was repeated in four patients and demonstrated deterioration of RV or LV function in two patients each.

These findings are consistent with the experience in Münster, where LV involvement of ARVC/D was mainly detected in patients with a long history of, and advanced stages of, RV dysfunction.

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