|INTERESTING CASE REPORT
|Ahead of print publication
Unusual Mechanism and Unusual Combination of Two Common Diseases: Mystery of the Missed Diagnosis
Satish K Parashar1, Samanjoy Mukherjee2
1 Senior Consultant Cardiologist and Director, Non-Invasive Cardiac Laboratory, Metro Hospital and Heart Institute, New Delhi, India
2 Senior Consultant Cardiologist, Manipal Hospital; Visiting Consultant, Metro Hospital and Heart Institute, New Delhi, India
|Date of Submission||21-Jun-2020|
|Date of Acceptance||25-Jun-2020|
|Date of Web Publication||09-Jun-2021|
Satish K Parashar,
Non-Invasive Cardiac Laboratory, Metro Hospital and Heart Institute, New Delhi
Source of Support: None, Conflict of Interest: None
Balloon mitral valvuloplasty (BMV) is an accepted treatment for certain subsets of patients of mitral stenosis. Prior to BMV, a full clinical and echocardiographic evaluation is done. This 36-years old lady of severe mitral stenosis had two BMV's including a three-dimensional transesophageal echocardiography at leading cardiac centers. However, an important echocardiographic finding was missed which would have altered the course of management. These details are discussed.
Keywords: Diastolic left ventricular outflow tract obliteration, echocardiography, hypertrophic cardiomyopathy, mitral stenosis
|How to cite this URL:|
Parashar SK, Mukherjee S. Unusual Mechanism and Unusual Combination of Two Common Diseases: Mystery of the Missed Diagnosis. J Indian Acad Echocardiogr Cardiovasc Imaging [Epub ahead of print] [cited 2021 Jul 23]. Available from: https://www.jiaecho.org/preprintarticle.asp?id=318100
| Introduction|| |
Hypertrophic cardiomyopathy (HCM) is a genetic disorder of the heart muscle, characterized by a small left ventricular (LV) cavity and marked hypertrophy of the myocardium, generally 1.5 cm or more, which is not explained by another cause. It is frequently accompanied by dynamic LV outflow tract (LVOT) obstruction. It is this obstruction to LVOT that is a major hallmark of the disease. The primary component of the obstruction, in the majority of patients, is systolic anterior motion (SAM) of the anterior mitral leaflet (AML), which contacts the septum during mid-to-late systole. The following case is an uncommon and intriguing combination of two diseases, resulting in a diagnostic challenge.
| Case Report|| |
A 36-years-old lady presented with shortness of breath for the last 3 months. There was no history suggestive of coronary artery disease or hypertension. She gave a classical history of rheumatic arthritis in 1992. In 2005, she started having progressive shortness of breath and was diagnosed as a case of mitral stenosis (MS). In 2006, she underwent balloon mitral valvuloplasty (BMV) at a leading cardiac centre with symptomatic relief. In 2010, she had recurrence of symptoms in the form of shortness of breath. She was diagnosed as having recurrence of severe MS, and a BMV was repeated in 2011, again with symptomatic relief. In May 2019, she underwent three-dimensional (3D) transesophageal echocardiography (TEE), which revealed severe MS with orifice area of 0.8 cm2, mean transvalvular gradient of 11 mmHg, peak systolic pulmonary artery pressure of 70 mmHg, and a soft left atrial appendage (LAA) clot with no other significant abnormality.
In February 2020, she reported to our institution for further management. Clinically, she was comfortable at rest. Jugular venous pulse was not raised, heart rate was 92/min, and blood pressure was 120/75 mmHg. No carotid bruit was heard. There were no signs of heart failure. P2 was normal. There was a prolonged 3/6 diastolic murmur in mitral area, with a grade 3–4/6 systolic murmur. Prior to echocardiogram, this systolic murmur was thought to be a murmur of mitral regurgitation. Electrocardiogram (ECG) [Figure 1] showed sinus rhythm, right axis deviation, left atrial (LA) enlargement, and an initial “R” wave in lead V1. There was no evidence of LV hypertrophy (LVH). An echocardiogram was performed, which revealed marked thickening of the interventricular septum (IVS) (about 20 mm) with asymmetrical septal hypertrophy and diastolic doming of AML [Figure 2]. The LV cavity was small, whereas LA was significantly overloaded. Other signs of significant MS with an orifice area of 0.8 cm2 were present. There was no SAM of AML [Figure 3]. Mid-systolic closure of the aortic valve was intermittently seen [Figure 4]. The aortic valve was not thickened and there was no evidence of subaortic membrane. However, significant late-systolic turbulence was present just below the LVOT. The continuous-wave Doppler interrogation across the LVOT yielded a peak gradient of 113 mmHg [Figure 5]. The pulsed-wave Doppler interrogation at the aortic valve revealed a velocity of only 2.41 m/sec. On a careful, frame-by-frame analysis of the images, the turbulence was noted to result from approximation of the papillary muscles with the thickened IVS [Figure 6]. Based on these findings, a diagnosis of MS + hypertrophic obstructive cardiomyopathy (HOCM) was made. A TEE was repeated to look for LA and or/appendage clot, any missed subaortic membrane, which is a well-known mimicker of HCM, and for LVOT anatomy. There was no LAA clot, nor any subaortic membrane and basal IVS showed significant hypertrophy with obliteration of LV outflow during late systole. Spontaneous echocardiographic contrast was present in the LA. She was started on sustained-release diltiazem 90 mg daily and sustained release metoprolol 50 mg daily; warfarin was continued. Digoxin was stopped and diuretic reduced. Although she had no symptoms at rest, but in view of severe MS and marked LV outflow gradient, she was advised to undergo MV replacement together with septal myomectomy. However, due to the current coronavirus disease 2019 crisis, and she being from another state, financial implications were present which delayed the surgical management. Possibly, due to subsequent strain of movement and the disease process, she developed acute pulmonary edema and could not be resuscitated.
|Figure 2: A zoomed parasternal long-axis view with significant thickening of interventricular septum (horizontal arrow), diastolic doming of anterior mitral leaflet (vertical arrow), a small left ventricular cavity, and left atrial overload|
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|Figure 3: Parasternal long-axis view showing absence of systolic anterior motion of anterior mitral leaflet as shown by arrow. A small left ventricular cavity and significant thickening of interventricular septum is also seen. MV: Mitral valve – anterior mitral leaflet|
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|Figure 4: Intermittent mid-systolic closure of the aortic valve is seen (arrow)|
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|Figure 5: A left ventricular outflow gradient of 113 mmHg present as recorded by continuous-.wave Doppler. Antegrade mitral flow is also seen. LVOT: left ventricular outflow tract|
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|Figure 6: Mechanism of left ventricular outflow obstruction in this patient. A- Parasternal long-axis view showing approximation of papillary muscle with the interventricular septum (arrow) during late-systole (please note the red marker on electrocardiographic trace for event timing); B- same finding seen in the apical long-axis view; C- color Doppler image in apical long-axis view clearly localizing the site of left ventricular outflow obstruction|
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| Discussion|| |
This patient had an uncommon combination of rheumatic MS and HOCM with an LV outflow gradient of about 113 mmHg whose value could be influenced by MS. Several cases of HOCM have been reported with other primary lesions of cardiac valves such as aortic stenosis, fixed subvalvular aortic stenosis, and mitral annular calcification. However, rheumatic MS has rarely been found to coexist with it. Only two cases could be traced from India. Goswami et al. in 1993 reported the first case of rheumatic MS and HCM with anomalous muscle bundle in the right ventricle, but without any significant resting LVOT obstruction, confirmed by hemodynamic studies. However, their patient showed LVH on ECG, which was a leading finding, but was not present in our case. Sharma et al. in 2016 reported a case of MS with HOCM in an imaging section, but no other details were mentioned, except that the patient had SAM of AML.
Hong et al., in their study extending over more than 22 years, at Mayo Clinic, could identify only 12 patients of HOCM with MS with an average LVOT gradient of about 75 mmHg. However, the average age of their patients was 70 ± 7.6 years. In view of this age group and rarity of rheumatic heart disease in America, the most likely explanation of MS in their patients was a degenerative MS rather than of rheumatic etiology. They proposed four mechanisms of LVOT obstruction when septal hypertrophy and significant mitral stenosis coexist: (a) classic SAM of mitral valve leaflets, (b) SAM of the tip of the mitral leaflet with severe limitation of leaflet motion, (c) septal encroachment toward the LVOT, and (d) calcific mitral leaflet distortion toward the LVOT. However, mitral leaflet SAM is unlikely to occur in severe rheumatic MS because mitral leaflets tips are invariably thickened, and the commissures are fused. In our patient also, LV outflow obstruction occurred because of papillary muscle approximation with the IVS and not because of mitral leaflet SAM. The obstruction was exacerbated by decreased LV cavity size and volume due to underlying severe MS and administration of diuretics. Possibly, digoxin could have also played a minor role.
The rarity of a combination of rheumatic MS with HOCM and lack of SAM as the cause of LV outflow obstruction resulted in a missed diagnosis of HOCM in our patient; otherwise, the patient could have undergone MV replacement and simultaneous septal myomectomy much earlier, and a life might have been saved. This teaches us to go beyond a focused echocardiographic examination and avoiding a “tunnel vision” and not getting biased by previous echocardiographic findings. The suggestive features for this combination of diagnosis include (a) awareness of this rare combination, (b) signs of MS, (c) LV type of apex beat, (d) ejection systolic murmur at the left mid sternal border, and (e) ECG signs of LVH.
| Conclusion|| |
A rare combination of rheumatic MS and HOCM with significant LV outflow gradient at rest, in a non-hypertensive patient, is described, who despite having multiple interventions in the past, had a missed diagnosis of HOCM. The unusual mechanism of LV outflow obstruction in this patient is discussed and the suggestive diagnostic features are also discussed. The ideal treatment in this case would be MVR and septal myomectomy. The septal myomectomy can itself be less extensive as compared to when performed as a stand-alone procedure.
As the patient expired and in the interest of this being an unusual case, the consent of the patient was not possible. However, all efforts have been made to conceal the identity of the patient.
Financial support and sponsorship
Conflicts of interest
Dr. Satish K. Parashar is an Editorial Board Member of the Journal of The Indian Academy of Echocardiography & Cardiovascular Imaging. The article was subject to the journal's standard procedures, with peer review handled independently of this editor and their research groups.
There are no other conflicts of interest.
| References|| |
Goswami KC, Reddy KS, Shrivastava S. Rheumatic mitral stenosis associated with hypertrophic cardiomyopathy and anomalous muscle bundle in the right ventricle. Int J Cardiol 1993;38:189-92.
Sharma J, Tewari S, Kapoor A. Unusual coexistent rheumatic mitral stenosis and hypertrophic cardiomyopathy. Asian Cardiovasc Thorac Ann 2016;24:290-1.
Hong J, Schaff HV, Ommen SR, Abel MD, Dearani JA, Nishimura RA. Mitral stenosis and hypertrophic obstructive cardiomyopathy: An unusual combination. J Thorac Cardiovasc Surg 2016;151:1044-8.
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]