A case of hypertrophic obstructive cardiomyopathy with aortic stenosis

Abstract

A 78-year-old woman complained of experiencing dyspnea (New York Heart Association II) and faintness. Echocardiography revealed she had asymmetric left ventricular hypertrophy, and a dynamic left ventricular outflow tract (LVOT) obstruction due to systolic anterior motion of the mitral valve. It also revealed calcification of the noncoronary cusp and a high-flow velocity in the LVOT (6.3 m/s). The planimetry measurement with transesophageal echocardiography was 0.89 cm² (aortic valve area/body surface area: 0.69 cm²/m²). Later, she was diagnosed with hypertrophic obstructive cardiomyopathy (HOCM) and aortic stenosis (AS). However, during the catheterization, the transvalvular pressure gradient (PG) was only 25 mmHg. In order to solve this, we performed a percutaneous transluminal septal myocardial ablation. As a result, the PG of the LVOT decreased from 152 mmHg to 25 mmHg.

We first thought that the LVOT obstruction had reduced the flow passing through the aortic valve, and restricted the motion of the aortic valve leaflets. We also considered the possibility that the aortic valve area had been underestimated. The hemodynamic study played an important role in the decision for the treatment plan. The present case was a combination of HOCM and “mild” AS.

<Learning objective: We know that we can distinguish between a left ventricular outflow tract obstruction and aortic stenosis using continuous-wave Doppler according to the phase of the peak gradient. However, if both are present, it is uncertain whether we can distinguish between them. It is necessary to measure the subaortic pressure and flow passing through the aortic valve accurately by catheterization in order to know which is the chief pathology.>

Introduction

Hypertrophic cardiomyopathy (HCM) is a primary disorder of the myocardium caused by a missense mutation in the cardiac sarcomere [1], [2]. This phenotypic expression occurs in 1 out of every 500 adults in the general population [3], [4]. Hypertrophic obstructive cardiomyopathy (HOCM) is characterized by asymmetric septal hypertrophy (ASH), systolic anterior motion (SAM) of the mitral valve, and a left ventricular outflow tract (LVOT) obstruction [4]. These abnormalities reduce the left ventricular (LV) diastolic performance and cause a high LV diastolic pressure, mitral regurgitation (MR), and low cardiac output, which lead to dyspnea, chest pain, and syncope [5], [6]. The diagnosis can be confirmed by abnormalities on the echocardiogram, which show not only an abnormal morphology, but also a high jet velocity in the LVOT. We here report a case of HOCM with aortic stenosis (AS). Further, we will discuss the pathology and treatment plan.

Case report

A 78-year-old woman diagnosed with HOCM was admitted for an evaluation of the severity of her AS. Six years previously, she initially experienced chest discomfort. She was diagnosed with HOCM by echocardiography because it revealed ASH, SAM, and a systolic pressure gradient (PG) in the LVOT (64 mmHg). We chose conservative drug therapy as the first-line approach, and she began to take beta-blockers (carvedilol 10 mg). However, after 6 years, the symptoms became worse and she also had dyspnea [New York Heart Association (NYHA) II] and faintness when she was admitted. She did not have a family history of sudden death. A physical examination revealed a midsystolic murmur (Levine III/IV) which significantly increased during the Valsalva maneuver and when standing up. Her blood pressure was 118/50 mmHg and heart rate was 78 beats/min. A laboratory test revealed mild anemia (hemoglobin 11 g/dl) and a high N-terminal-pro B-type natriuretic peptide level (4822 pg/ml). The electrocardiogram at rest exhibited normal sinus rhythm. There was ST-segment depression and terminal T-wave negativity in leads II, III, aVF, V5, and V6. The chest X-ray did not reveal any cardiomegaly. Transthoracic echocardiography (TTE) revealed ASH (the septal wall thickness was 17 mm and posterior wall thickness 13 mm). The LV diameters were 37 mm in the end-diastolic phase and 23 mm in the end-systolic phase. The ejection fraction was 60%. The mitral valve exhibited a significant SAM phenomenon, with complete systolic septal contact. The MR was mild. There was a calcification change in the noncoronary cusp of the aortic valve. The aortic valve area (AVA) was unclear due to the calcification change. Continuous-wave Doppler echocardiography revealed that the PG in the LVOT was 159 mmHg at rest (Fig. 1). Magnetic resonance imaging also depicted an obstructive LVOT, ASH, and SAM, but we could not confirm any delayed contrast enhancement of the hypertrophic cardiac muscle. We also performed transesophageal echocardiography (TEE) to measure an accurate AVA. The planimetry measurement of the TEE showed that the AVA was 0.89 cm² (AVA/body surface area: 0.69 cm²/m²). It also revealed that there was a calcification change in the noncoronary cusp and the leaflet motion was slightly decreased. We could confirm a mosaic flow in the LVOT (Fig. 2). The Holter electrocardiography showed that the total heartbeats were 93,252/day. The minimum heart rate was 56 bpm and maximum heart rate 86 bpm. The Holter electrocardiography did not reveal any ventricular tachycardia.

Fig. 1.

The transthoracic echocardiograms. (a) The transthoracic echocardiogram in the parasternal long-axis view during the mid-systolic period reveals asymmetric septal hypertrophy, systolic anterior motion (SAM) of the mitral valve, and a left ventricular outflow tract (LVOT) obstruction. (b) The short-axis view of the aortic valve reveals a calcification of the noncoronary cusp. (c) This three-chamber view also shows SAM and an LVOT obstruction. There were calcific changes in the aortic valve. (d) Continuous-wave Doppler echocardiography revealed that the pressure gradient was 159 mmHg (6.3 m/s) at rest.

Fig. 2.

The transesophageal echocardiograms. (a) The transesophageal echocardiogram in the long-axis view during the mid-systolic period also shows systolic anterior motion and left ventricular outflow tract (LVOT) obstruction. (b) The short-axis view shows the calcific changes of the aortic valves, especially that of the noncoronary cusp. (c) The color Doppler in the long-axis view exhibits a mosaic signals in the LVOT.

We performed a cardiac catheterization and hemodynamic study (we used a specific catheter similar to a pig-tail catheter). Firstly, we measured the right atrial pressure (RAP), right ventricular pressure (RVP), pulmonary artery pressure (PAP), and pulmonary capillary wedge (PCWP) pressures and cardiac output (CO) using a Swan-Ganz catheter (RAP: 9 mmHg, RVP: 72/5–11 mmHg, PAP: 70/26(48) mmHg, PCWP: 42 mmHg, CO: 5.17 L/min) The hemodynamic study revealed a high RAP, evidence of pulmonary hypertension, high left atrium pressure (the mean PCWP was 42 mmHg even though the end-diastolic pulmonary artery pressure was 26 mmHg) and adequate CO. We then placed one catheter in the ascending aorta, and another into the LV cavity. We measured the intra-ventricular pressure and ascending aortic pressure at the same time. When we placed the catheter in the LV apex, the peak to peak PG was 132 mmHg. However, when we pulled it back to the subaortic valve, the PG decreased to 25 mmHg (Fig. 3a and b). We thought that the true transvalvular PG was 25 mmHg. Coronary angiograms revealed no arteriosclerotic changes or narrowing of the extramural coronary arteries. Left ventriculography, as well as the echocardiogram, revealed SAM and an LVOT obstruction. It also revealed grade II MR due to the SAM.

Fig. 3.

The pressure measurements of the left ventricular (LV) cavity and ascending aorta. (a) The pressure measurement of the LV apex and ascending aorta before the procedure. The difference between the two peak pressures was 132 mmHg. (b) The pressure measurement of the left ventricular outflow tract (LVOT) and ascending aorta before the procedure. The difference between the two peak pressures was only 25 mmHg. (c) The pressure measurement of the LV cavity and ascending aorta after the procedure. The catheter was pulled from the LV apex to the LVOT. The pressure gradient between the LV cavity and ascending aorta improved, and there was no difference between the LV apex and LVOT. The pressure gradient between the LVOT and ascending aorta did not change.

As a result, we determined that the AS was not so severe. Through the informed consent process, we decided to perform a percutaneous transluminal septal myocardial ablation (PTSMA).

We performed an elective PTSMA with myocardial contrast echocardiography (MCE). First, we inserted a temporary pacemaker into the right ventricle. Following that, we introduced a balloon catheter into the first septal branch of the left anterior descending coronary artery. After the balloon was inflated, the distribution of the first septal branch was verified by contrast two-dimensional echocardiography after an injection of an echo contrast agent. After confirming which territory of the basal septum contributed to the LVOT obstruction, we infused 1.7 ml of alcohol selectively through an over-the-wire catheter with the balloon inflated. We injected a little morphine hydrochloride because the patient complained of crushing pressure in her precordial chest. We confirmed the complete ablation of the basal septum with the MCE.

Immediately after the PTSMA, we measured each intra-cardiac pressure and the PG between the LV cavity and ascending aorta with the catheters again, and recognized a significant decrease from 132 mmHg to 25 mmHg (Fig. 3c). (RAP: 12 mmHg, RVP: 47/6–12 mmHg,PAP: 52/25(36) mmHg, PCWP: 23 mmHg,CO: 4.90 L/min).

After the procedure, the patient was monitored in the coronary care unit for one day. No complications occurred, in particular, no atrio-ventricular block. The maximum increase in the creatine kinase level was 1091 IU/L, 7 hours after the procedure. The systolic murmur decreased from III to I–II. The echocardiography revealed a maximum LVOT gradient of 25 mmHg at rest. The motion of the aortic valve leaflet improved unexpectedly. The patient was discharged from the hospital without any complications. The patient received drug therapy (bisoprolol 5 mg/day and cibenzoline 100 mg/day) after discharge. We followed up the PG with TTE. There was no recurrence of the dyspnea or faintness during a follow-up period of 20 months. Currently, her NYHA grade has improved to I and she is trying to do yoga exercises.

Discussion

The present case was an elderly female patient that appeared to have HOCM complicated with AS. The cardiac catheterization allowed us to make an accurate estimate of the PG and its severity. Properly speaking, patients with valvular AS who undergo a retrograde catheterization of the aortic valve have a substantial risk of experiencing a clinically apparent cerebral embolism, and frequently have silent ischemic brain lesions [7], [8], [9]. In addition to this, it was reported that the Doppler-derived AVA calculated by the continuity equation correlated well with the catheterization-derived AVA calculated by the Gorlin equation [8], [9], [10]. So currently, it is common that catheterization to assess the severity of the AS is not performed. However, in this case, it was difficult to assess the severity of the AS using the continuity equation because of the LVOT obstruction. To begin with, continuous-wave Doppler echocardiography measures the peak blood acceleration on its cursor line [10]. So the LVOT and aortic valve are too close to each other to estimate the PG of each with continuous-wave Doppler echocardiography. Further, the blood flow passing across the aortic valve is not a straight flow because of the LVOT obstruction. We know that we can distinguish between HOCM and AS in order to confirm the phase of the peak PG. In other words, if the peak occurs during the early to middle systolic period that means the Doppler wave is the flow passing through the aortic valve. Further, if the peak is during the end-systolic period, that means the Doppler wave is the flow passing through the LVOT. In this case, we could confirm that the peak of the Doppler wave was during the end-diastolic period. So we guessed that the chief pathology was HOCM, and the AS was not as severe as it seemed. However, it was not known whether a differential diagnosis was appropriate for patients with coexisting HOCM and AS. We thought that performing assessments with continuous-wave Doppler echocardiography was not applicable in cases with a combination of HOCM and AS.

Furthermore, we thought that there were some possibilities of underestimating the AVA with the TEE planimetric method as well as the TTE continuity equation. We speculated that the blood flow across the aortic valve became weaker with the LVOT obstruction, so the motion of the aortic valve might have become reduced. In addition to that, we sometimes find that the aortic valve in HOCM patients is not adequately open during the mid-end systolic phase due to SAM phenomena. As a result, we could have underestimated the AVA. To determine this, we performed a catheter test and measured the stroke volume (SV) and CO and sub-aortic pressure. In this case, the force used in pushing the aortic valve was adequate (the SV was 70 ml and CO 5.17 L/min) and the PG of the AV was 25 mmHg. That meant that we could trust the AVA measurements obtained by the TEE planimetric method. In other words, if the aortic valve was not adequately opened with an adequate output, then there was a problem with the aortic valve itself.

We experienced 3 cases with a combination of HOCM and AS. We followed up each transvalvular PG because we wondered whether or not it increased when the PG in the LVOT became reduced (we measured the transvalvular PG after the PTSMA procedure). However, in all 3 cases, the transvalvular PG decreased for a period (Fig. 4). In other words, there was almost no difference in the transvalvular PG between that before and after the procedure. This meant that a procedure reducing the PG in the LVOT does not increase the transvalvular PG. However, there is the possibility of increasing the transvalvular PG after the PTSMA in cases in which there is extremely severe calcific changes in the valves. We recommend measuring the transvalvular PG immediately after the PTSMA and to perform periodic follow-up evaluations using the TEE planimetry method.

Fig. 4.

The changes in the transvalvular pressure gradient (PG) in 3 cases. We measured the transvalvular PG before and after the procedure. In all cases the transvalvular PG decreased after the percutaneous transluminal septal myocardial ablation (PTSMA), and did not increase.

Conflict of interest

Authors declare no conflict of interest.