Severe Midventricular Hypertrophic Obstructive Cardiomyopathy and Apical Aneurysm.

A 40-year-old man was found to have hypertrophic cardiomyopathy (HCM) with severe mid ventricular obstruction. The obstruction produced two distinct left ventricular chambers with an estimated 60 mmHg continuous wave (CW) Doppler intraventricular gradient. Pulsed wave (PW) Doppler showed high velocity systodiastolic flow from apex to base and flow from base to apex confined mostly to the second half of diastole. Cardiac magnetic resonance (CMR) showed midventricular obstruction, due to septal, parietal, and to an hypertrophic, double posteromedial papillary muscle; an apical aneurysm was detected. Aneurysm is underdiagnosed by echocardiography in HCM and an accurate anatomic definition is needed if surgery is planned; thus, a CMR should always be obtained in these patients.

A 40-year-old man underwent an echocardiogram because of dyspnea and chest pain on effort; Electrocardiogram (ECG) showed left ventricular hypertrophy with secondary changes of repolarization. Echocardiogram showd midventricular obstruction of the left ventricle (LV); continuous wave (CW) Doppler showed high velocity jet (3,8 m/s), originating at the level of obstruction, with a peak estimated gradient of about 60 mmHg; pulsed wave (PW) Doppler showed systolic flow in the apical chamber directed from apex to base, continuing well after the end of electrical systole and flow from base to apex mostly in the second half of diastole [Figure 1a and b]. Cardiac magnetic resonance (CMR) showed midventricular obstruction, due to hypertrophy of septum, LV lateral wall, and double posteromedial papillary muscle; producing two distinct proximal and distal chambers [Figure 2a and b]. Maximal septal thickness was 22 mm at midventricular level. Apical hypertrophy of the right ventricle was also shown [Figure 2]. An apical aneurism (AA) of the LV was found [Figures 2–3]. No LV outflow tract obstruction was present.

Figure 1

Echocardiogram two-dimensional (2D), continuous wave (CW) and pulsed wave (PW) Doppler; four chamber view. (a): CW 3.8 m/s jet directed towards left ventricle (LV) base is shown; flow velocity is maximal in proto- and end-systole, with marked attenuation in mid-systole, accordingly with midventricular obstruction. (b) PW, sampling in the apical chamber, just apical to obstruction. High velocity systolic flow directed from apex to base is seen; flow continues well after the end of electrocardiogram (ECG) T wave (thus during electrical diastole). Base to apex flow is mostly in end diastole (arrows)

Figure 2

Cine sequence, four chamber view. (a) End diastolic frame and (b) systolic frame. Midventricular hypertrophy with septal leftward bulging and hypertrophic double posteromedial papillary muscle are shown; severe systolic obstruction with double-chambered appearance of LV is caused by joining of septum and papillary muscle. Systolic expansion of tinned apex is also shown, as well as apical and mid right ventricle hypertrophy

Figure 3

Inversion recovery-contrast enhanced 3D sequence, four chamber view. Late enhancement of thinned left ventricular apex is shown. Intermediate intensity signal of border zone is shown (arrows). No thrombus is detected

Repeated Holter recordings showed only infrequent, isolated diurnal ventricular ectopic activity. No history of familiar sudden death was reported.

Midventricular obstruction of the LV is an increasingly encountered phenotypic variant of hypertrophic cardiomyopathy (HCM).[12] Abnormal and hypertrophic papillary muscles commonly are seen in these cases[13] impinging in a ventricular cavity reduced by mid ventricular septal and free wall hypertrophy. Apical dilation is common and AA occurs in severe cases;[245678910] such as the present one. AA occurs uncommonly in HCM patients as a whole, but is common in midventricular obstruction cases. Maron et al.,[5] found an AA in 28 (2%) of 1,299 HCM patients, but each one of these 28 patients had midventricular (19, 68%) or apical (9, 32%) hypertrophy. Maximal wall thickness was similar in AA patients with midventricular and apical hypertrophy (18 and 20 mm, respectively). AA is thought to be the result of repeated ischemia resulting from reduced capillary density, hyperplasia of the arterial media, increased perivascular fibrosis, and myocardial bridging.[567] AA should be looked for in every case of midventricular HCM because it portends a severe arrhythmic risk, most probably due to reentry through the border zones of the AA, containing fibrous tissue interspersed with vital muscle.[8910] Thrombotic apposition in AA is not uncommon[158] and can be associated with embolism.[5]

AA in HCM is considered a potential sudden death risk modifier that can contribute to resolution of ICD decision.[5678910] At the site of obstruction a flow disturbance is seen, that can even present as paradoxic flow, that is, systolic flow towards the apex and diastolic flow from the apex to base.[1112] Paradoxic flow is related to the diskynesia of the apex due to the AA. In the present case a mixed pattern was seen, with systolic flow in the apical chamber directed from apex to base continuing well after the end of electrical systole and flow from base to apex mostly in the second half of diastole [Figure 1b]. This pattern, representing an almost continuous flow, is similar to the one described by Hsieh et al.,[13] Flow from apex to base during systole and isovolumic relaxation has been described in midventricular obstruction-no AA HCM,[14] thus a continuum of flow patterns seems to exist in this disease, spanning from totally paradoxic flow to delayed empting and filling of the apical chamber. The variable pattern of flow arguably is the end result of the complex interaction between variable obstruction severity, AA, delayed relaxation, and contraction of apical chamber.

An issue is the relatively poor sensitivity of echocardiography in imaging AA, as an AA was recognized by echocardiography in only 16 of 28 patients (57%), but by CMR in the 12 patients undetected by echocardiography.[5]

Surgical treatment by transaortic midseptal and papillary muscle reduction has been used in some cases.[15] More recently an apical approach to septal surgical remodeling, alone or combined with other procedures including AA repair, has been utilized with excellent results and no mortality.[16] Intraventricular gradient was reduced from 64 ± 32 mmHg before myectomy to 6 ± 12 mmHg.[16]

In the present case, a temptative treatment with propranolol 160 mg/day in divided doses reduced symptoms but not the gradient. The patient is now on list for surgery.