Unmasking the severity of aortic stenosis by pharmacological elimination of left ventricular outflow tract obstruction: a case report

Abstract

Background

Left ventricular outflow tract (LVOT) obstruction may occur with aortic stenosis (AS). However, the severity of AS is difficult to determine in this condition because the dynamic pressure gradient in LVOT obstruction influences the blood flow across the aortic valve.

Case summary

A 74-year-old woman was referred to our hospital having complaints of exertional dyspnoea and chest pain. Transthoracic echocardiography demonstrated LVOT obstruction with peak pressure gradient of 93 mmHg and ‘moderate’ AS with 3.9 m/s peak velocity and mean pressure gradient of 26 mmHg. Coronary angiography did not indicate any significant coronary artery disease. The pressure gradients at LVOT and aortic valve were measured as 34 mmHg and 76 mmHg via a pressure wire-pullback analysis, respectively. Intravenous 2 mg propranolol and 70 mg cibenzoline were administered to minimize the LVOT obstruction. Subsequently, these pressure gradients changed to 2 mmHg and 96 mmHg, respectively. The patient was finally diagnosed with ‘severe’ AS concomitant with LVOT obstruction. Therefore, surgical aortic valve replacement and myectomy were performed to remove the double obstruction.

Discussion

Herein, we present a case of ‘double’ LVOT obstruction due to dynamic myocardial component and fixed aortic component. Although the severity of AS is known to be influenced by LVOT obstruction, the present case is novel to demonstrate the phenomenon by using a pressure wire during pharmacological intervention. An accurate evaluation of the AS severity is important to provide adequate treatment. Therefore, the severity of AS should be evaluated while minimizing the LVOT obstruction.

Introduction

Left ventricular outflow tract (LVOT) obstruction occasionally exists with aortic stenosis (AS).¹ However, transthoracic echocardiography (TTE) is difficult to evaluate the ‘double’ obstruction separately, because the doppler ultrasound flow created by each obstruction is almost coaxially recorded. Furthermore, the severity of AS is difficult to evaluate in this condition because the LVOT obstruction influences the blood flow across the aortic valve. Herein, we present a case of the ‘double’ obstruction, in which the severity of AS deteriorated during minimizing LVOT obstruction by pharmacological intervention, demonstrated by using a pressure wire.

Timeline

Case report

A 74-year-old woman, who had a history of dyslipidaemia and systemic hypertension treated with 10 mg amlodipine for 10 years, was referred to our facility by a primary care doctor for exertional dyspnoea and chest pain. Her heart failure condition, according to the New York Heart Association Classification (NYHA), was considered stage III, and the symptoms continued for 3 months. A right parasternal pansystolic murmur and bilateral leg oedema were detected on physical examination. Serum N-terminal pro-brain natriuretic peptide (NT-proBNP) was found to be as high as 2826 pg/mL (normal range, 0–125 pg/mL), while the chest X-ray demonstrated cardiac enlargement with bilateral pleural effusion. Electrocardiogram showed normal sinus rhythm with a heart rate of 90 beats per minute with strain-pattern ST-segment depression in V4–V6 leads (Figure 1). Transthoracic echocardiography on admission demonstrated normal left ventricular ejection fraction, global left ventricular hypertrophy with 14.5 and 15.1 mm of septal and posterior wall thickness, LVOT obstruction with a peak pressure gradient of 93 mmHg, and ‘moderate’ AS with 3.9 m/s peak velocity and mean pressure gradient of 26 mmHg (see Video S1, Figure 2). Asymmetric septal hypertrophy in LVOT and a systolic anterior movement of the mitral valve leaflet were also recorded. Coronary angiography did not show any significant coronary artery disease (Figure 3). The severity of LVOT obstruction and AS was evaluated by the following: (i) A pressure wire (PressureWire™ X, Abbott, USA) was placed into the left ventricle through an angiographic diagnostic catheter with a 0.014 inch wire to stably record the simultaneous pressure between the left ventricle (LV) and aorta (Figure 4). (ii) Intraventricular pressures were measured by pressure-wire pullback from LV to aorta. The systolic, diastolic, and mean pressures at each point were as follows: 202/4/83 mmHg at LV, 168/10/81 mmHg at LVOT, and 92/53/69 mmHg at the ascending aorta (Figure 5A). Right cardiac catheterization was subsequently performed, in which cardiac output (CO) and pulmonary artery wedge pressure (PAWP) were measured as 5.44 L/min and 21 mmHg. Aortic valve area (AVA) was estimated as 1.32 cm² calculated by the Gorlin equation.² (iii) Intravenous 2 mg propranolol and 70 mg cibenzoline were administered to minimize the LVOT obstruction. (iv) Intraventricular pressures were measured again, and the respective pressures were changed as follows: 192/9/83 mmHg at LV, 190/9/81 mmHg at LVOT, and 94/58/69 mmHg at ascending aorta (Figure 5B). CO and PAWP were measured as 4.08 L/min and 20 mmHg, and the estimated AVA was changed to 0.90 cm².

Oral 5 mg bisoprolol and 300 mg cibenzoline were prescribed after the cardiac catheterization. Follow-up TTE on Day 9 demonstrated LVOT obstruction with a peak pressure gradient of 29 mmHg and severe AS with 4.4 m/s of peak velocity and 50 mmHg of mean pressure gradient. Based on these invasive and non-invasive evaluations, the patient was diagnosed as ‘severe’ AS concomitant with LVOT obstruction. Therefore, surgical aortic valve replacement and myectomy were performed on Day 22. During the procedure, severe calcified aortic valve was replaced with INSPIRIS RESILIA 19 mm, and myectomy was performed to the massive myocardium in LVOT. The patient underwent cardiac rehabilitation without any significant periprocedural complications, and her heart failure condition had improved to NYHA Class I, continuing oral 5 mg bisoprolol and 10 mg amlodipine. She was discharged from our hospital without any dyspnoea or angina on Day 32. Her heart failure condition was well-controlled without bilateral leg oedema or gain weight 1 month after the discharge. Serum NT-proBNP was decreased to 1458 pg/mL, and cardiac enlargement was improved on chest X-ray. Transthoracic echocardiography demonstrated LVOT obstruction with 12 mmHg peak pressure gradient and mild AS with 2.5 m/s of peak velocity and 25 mmHg of mean pressure gradient.

Discussion

Although genetic examination or biopsy was not performed on the patient, her myocardial hypertrophy was considered hypertensive hypertrophy due to long period of systemic hypertension and severe AS. In addition, concomitant septal bulge may lead the LVOT obstruction in the present case. Indeed, early studies (autopsy and echocardiography) have estimated that approximately 10% of patients with haemodynamically significant valvular AS also have septal hypertrophy, thereby creating a risk for LVOT obstruction.¹ Hence, the evaluation of the concomitant AS severity is important because the elimination of both obstructions would be necessary if the patient with LVOT obstruction had severe AS. However, the evaluation of AS severity delivers uncertain results because the LVOT obstruction can change the blood flow across the aortic valve. It is difficult to predict how the elimination of LVOT obstruction affects the concomitant AS severity. Indeed, published cases demonstrate worsened and unchanged AS after treatment of the concomitant LVOT obstruction.^3,4 Therefore, AS severity should be evaluated while minimizing the concomitant LVOT obstruction.

The previously reported beta-blockade and/or cibenzoline stress echocardiography was performed for trying to evaluate the severity of AS while minimizing LVOT obstruction.^5,6 However, accurate evaluation is difficult under this condition because the two velocity profiles of both AS and LVOT obstruction might overlap by TTE.⁷ Therefore, invasive evaluations using a pressure wire were performed with intravenous propranolol and cibenzoline to minimize LVOT obstruction in the present case.⁸ Both medications have a negative inotropic effect on cardiac contractility; thus, LVOT obstruction caused by hypertrophic septal myocardium would be relieved. As a result, the pressure gradient at the aortic valve increased and the estimated AVA decreased, whereas the pressure gradient at LVOT decreased due to the pharmacological intervention. The patient finally underwent surgical aortic valve replacement in addition to septal myectomy. However, if the diagnosis of ‘severe’ AS had been missed, she would have undertaken only alcohol septal ablation for the LVOT obstruction and would have possibly developed worsened AS.

This invasive evaluation has some potential advantages. First, pressure gradients at each point in LVOT are clearly demonstrated. This aspect is helpful when the Doppler echo has a difficulty distinguishing AS from LVOT obstruction. Second, the real-time pressure gradients were visualized during the pharmacological intervention. Therefore, an interventionist can predict whether a patient needs invasive treatment for AS after removing LVOT obstruction. Further, this method is easy to perform because it can be completed using single arterial puncture.

Conclusion

The present case demonstrated that the pharmacological treatment to minimize the concomitant LVOT obstruction unmasked ‘severe’ AS in the catheter laboratory. The severity of AS should be evaluated while minimizing the LVOT obstruction not to miss the true ‘double’ obstruction.

Lead author biography

Yoshihiro Harano is a general cardiologist who graduated from Gifu University School of Medicine, Gifu, Japan, in 2018. Since 2021, he has worked at Gifu Heart Center (Gifu, Japan) as a senior resident with specific interest in catheter intervention. Memberships: 2019 The Japanese Society of Internal Medicine, 2019 The Japanese Heart Rhythm Society, 2020 The Japanese Circulation Society, and 2021 The Japanese Association of Cardiovascular Intervention and Therapeutics.

Supplementary material

Supplementary material is available at European Heart Journal – Case Reports.

Acknowledgements

We acknowledge all the medical staff who contributed to our patient care at the Department of Cardiology in the Gifu Heart Centre.

Slide sets: A fully edited slide set detailing this case and suitable for local presentation is available online as Supplementary data.

Consent: The authors confirm that written consent for submission and publication of this case report, including images and associated text, has been obtained from the patient according to the COPE guidelines.

Funding: None declared.

References

Author notes