Assessment of Left Ventricular Structural Abnormalities

Myocardial Crypts

Myocardial crypts (or clefts) have been defined as discrete V-shaped extensions of the blood pool inserting more than 50% into the compact myocardial wall that tend to be less visible during systole and are not associated with local hypokinesis or dyskinesia. Increased prevalence of crypts has been reported in carriers of the gene for hypertrophic cardiomyopathy (as much as 81%). However, myocardial crypts also are seen in normal subjects, so their precise significance has yet to be determined.

For CCT images of myocardial crypts, see Figures 20-1 and 20-2 ;

Figure 20-1, Multiple composite images from a cardiac CT study in a patient with hypertrophic cardiomyopathy demonstrating a basal inferior crypt and an enlarged left atrium.

Figure 20-2, Composite images from a cardiac CT and cardiac MRI (CMR) demonstrate small crypt-like formations involving the inferior basal wall of the left ventricle. The underlying coronary arteries are normal. There was no history of hypertrophic cardiomyopathy. Similar findings were confirmed on CMR, with no delayed enhancement. See Video 20-1.

Myocardial Diverticulum

Congenital left ventricular (LV) diverticula are rare cardiac malformations characterized as outpouchings of the myocardium and can be fibrous or muscular. The prevalence has been reported between 0.02% and 0.04%. They are associated with other congenital abnormalities in about 70% of cases. Muscular diverticula typically are apical and have a full-thickness myocardial wall with preserved systolic contraction. Diverticula can be differentiated from crypts or clefts by a narrow mouth but a wide outpouching extending beyond the normal LV margins. Cardiac CT (CCT) has been proposed as useful for differentiating aneurysm from pseudoaneurysm by exclusion of coronary artery disease, visualization of the LV wall layers, and dynamic assessment of regional wall function ( Fig. 20-3 ).

Figure 20-3, A 29-year-old asymptomatic man was referred for treatment of Crohn’s disease. Before commencing treatment, the patient underwent cardiac assessment. A, An echocardiogram showed a localized low-echoic cavity with a discontinuity in the basal part of the left ventricular (LV) lateral wall close to the atrioventricular groove. B, Reconstructed multidetector CT clearly showed the spatial relationship between the coronary artery and the pseudoaneurysm ( arrows ). C and D, Color Doppler imaging showed bidirectional blood flow between the LV and the cavity through a narrow communication, consistent with a diagnosis of LV pseudoaneurysm. Coronary angiography showed no atherosclerotic stenosis. E and F, Remarkably, the proximal part of the left circumflex coronary artery ( arrows ) became very thin during systole due to a dyskinetic expansion of the pseudoaneurysm, indicating a myocardial bridging-like squeeze

Post-Infarction Ventricular Pseudoaneurysms, Septal Rupture, and Intramyocardial Hematoma

Pseudoaneurysms are an uncommon complication of acute myocardial infarction, occurring in less than 1% of cases. Cardiac surgery, penetrating or other trauma, and infection also can lead to the development of these abnormalities. The excellent spatial resolution of CT should be ideal for identifying the myocardial wall disruption. Single case reports have demonstrated the ability of CCT to depict post-infarction ventricular pseudoaneurysms, and coronary anatomy.

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Post-infarction septal rupture and intramyocardial hematoma also have been noted in single case reports.
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For CCT images of post-infarction pseudoaneurysms, see Figure 20-4 .
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For CCT images of post-infarction septal rupture, see Figures 20-5 and 20-6 ; ,