A systematic approach to echocardiography in hypertrophic cardiomyopathy: a guideline protocol from the British Society of Echocardiography.

Hypertrophic cardiomyopathy (HCM) is a relatively common inherited cardiac condition with a prevalence of approximately one in 500. It results in otherwise unexplained hypertrophy of the myocardium and predisposes the patient to a variety of disease-related complications including sudden cardiac death. Echocardiography is of vital importance in the diagnosis, assessment and follow-up of patients with known or suspected HCM. The British Society of Echocardiography (BSE) has previously published a minimum dataset for transthoracic echocardiography, providing the core parameters necessary when performing a standard echocardiographic study. However, for patients with known or suspected HCM, additional views and measurements are necessary. These additional views allow more subtle abnormalities to be detected or may provide important information in order to identify patients with an adverse prognosis. The aim of this Guideline is to outline the additional images and measurements that should be obtained when performing a study on a patient with known or suspected HCM.

Introduction

The British Society of Echocardiography (BSE) Education Committee has previously published a minimum dataset for a standard adult transthoracic echocardiogram (1). This Guideline specifically states that the minimum dataset is usually sufficient only when the echocardiographic study is entirely normal. The aim of the BSE Education Committee is to publish a series of appendices to cover specific pathologies supporting this minimum dataset.

The intended benefits of such supplementary recommendations are to:

Support cardiologists and echocardiographers to develop local protocols and quality control programs for adult transthoracic study.

Promote quality by defining a set of descriptive terms and measurements, in conjunction with a systematic approach to performing and reporting a study in specific disease states.

Facilitate the accurate comparison of serial echocardiograms performed in patients at the same or different sites.

This Guideline gives recommendations for the image and analysis dataset required in patients either being assessed for, or with a known diagnosis of hypertrophic cardiomyopathy (HCM). The views and measurements are supplementary to those outlined in the minimum dataset and are given assuming that a full study will be performed in all patients.

When the condition or acoustic windows of the patient prevent the acquisition of one or more components of the supplementary dataset, or when measurements result in misleading information (e.g. off-axis measurements), this should be stated.

This document is a guideline for echocardiography in HCM and will be updated in accordance with changes directed by publications or changes in practice (Table 1).

Table 1

Additional views and measurements to be obtained in patients with known or suspected hypertrophic cardiomyopathy

View (modality)	Measurement	Explanatory note	Image
PLAX (2D/MM)	IVSd	IVSd measure >3 cm is a key marker of increased risk (2) Demonstrate if ASH is presentMeasure RV wall thickness if on axis
PLAX (2D/MM)	LA size	Measure LA size (anterior–posterior diameter). LA diameter is one of the criteria used to estimate risk of sudden cardiac death (3)
PLAX (MM and CFM)	MV leaflet tips and AV leaflet tips	Demonstrate if SAM is present on M-Mode and for colour flow turbulence within the LVOTDemonstrate if early closure of the AV
PSAX MV (2D)	Frozen 2D image: obtain wall thickness measurements from level of the basal LV. Measure at four points, using clock face references (12, 3, 6, 9 o'clock)	To assess for asymmetric and symmetric segmental LV hypertrophySegmental hypertrophy >1.5 cm (2) with normal or small LV internal cavity dimensions is strongly suggestive of HCM (in absence of other pathologies such as hypertension)
PSAX PM (2D)	2D frozen image at the mid-LV level. Measure at four points, using clock face references (12, 3, 6, 9 o'clock)	Avoid off-axis measurements, papillary muscle and trabeculations
PSAX Apex (2D)	Apical-level measure at two points (12 and 6 o'clock)	Apical hypertrophy may be present if apical/basal lateral ratio is >1.5. Consideration should be given to use of LV opacification contrast
Modified PSAX (2D and PW/CW)	RV wall thickness and RVOT forward flow velocities	Modify both the RV inflow and outflow to assess for RVH and RVOT obstruction. RVH present if >0.5 cm
Modified A4C (2D)	RV wall thickness	If clear images can be obtained, measure RV wall thickness. Otherwise measurement from PLAX and subcostal views is preferred. RVH present if >0.5 cm
A4C and A2C (2D)	LA volume	Index LA volume to BSA (4)
A4C (CFM)	Aetiology and severity of mitral regurgitation	If SAM is present, MR may be eccentric and is usually mid/late systolic
A4C (PW TDI)	Systolic (s'), early (e') and atrial (a') relaxation velocities at anterolateral LV annulus	Reduction in s' or e' velocities below normal range for age and sex (5) Assess for elevated LVEDp by measuring E/e'. Average septal and lateral velocities for e'. Abnormal if >10 (4)
A4C (PW TDI)	Systolic (s'), early (e') and atrial (a') relaxation velocities at inferoseptal LV annulus	Reduction in Sa or Ea velocities below normal range for age and sex (5) Assess for elevated LVEDp by measuring E/e'. Average septal and lateral velocities for e'. Abnormal if >10 (4)
A5C and A3C (CFM)		Locate turbulent flow both within the LV cavity and the LVOT
A5C and A3C (PW/CW)	Quantify LVOT/LV intracavity dynamic flow gradient	Sample PW Doppler throughout the LV cavity, paying particular attention to areas with turbulent flow. HPRF/CW Doppler may be appropriate if aliasing occurs. Take care not to include MR jet in sample volume. A Valsalva manoeuvre should be performed in the sitting and semi-supine position (and then on standing if no gradient is produced) to assess dynamic LVOT gradients. The peak gradient (rest or Valsalva) should be recorded. In addition, exercise stress echocardiography should be considered in patients with LVOT gradients <50 mmHg at rest (with or without Valsalva) (3)
A2C (PW TDI)	Systolic (s'), early (e') and atrial (a') relaxation velocities at inferior LV annulus	Reduction in s' or e' velocities below normal range for age and sex (5)
A2C (PW TDI)	Systolic (s'), early (e') and atrial (a') relaxation velocities at anterior LV annulus	Reduction in s' or e' velocities below normal range for age and sex (5)

Abbreviations

Views
A2C	Apical two chamber
A4C	Apical four chamber
A5C	Apical five chamber
A3C	Apical three chamber or apical long axis
PLAX	Parasternal long axis
PSAX	Parasternal short axis
SC	Subcostal
SSN	Suprasternal
Modality
CFM	Colour flow Doppler
CW	Continuous-wave Doppler
PW	Pulse wave Doppler
TDI	Tissue Doppler imaging
Measurement and explanatory text
a'	Lateral and/or septal late annular relaxation velocity
Ao	Aorta
ASH	Asymmetrical septal hypertrophy
AV	Aortic valve
BSA	Body surface area
DT	Deceleration time
e'	Lateral and/or septal early annular relaxation velocity
HCM	Hypertrophic cardiomyopathy
HPRF	High pulse repetition frequency
IVC	Inferior vena cava
IVSd	Interventricular septal width in diastole
LA	Left atrium
LLPV	Left lower pulmonary vein
LPA	Left pulmonary artery
LUPV	Left upper pulmonary vein
LV	Left ventricle
LVEDp	Left ventricular end-diastolic pressure
LVIDd/s	Left ventricular internal dimension in diastole and systole
LVOT	Left ventricular outflow tract
LVPWd	Left ventricular posterior wall width in diastole
MAPSE	Mitral annular plane systolic excursion
MR	Mitral regurgitation
MV	Mitral valve
PA	Pulmonary artery
PAP	Pulmonary artery pressure
PHT	Pressure half-time
PR	Pulmonary regurgitation
PS	Pulmonary stenosis
PV	Pulmonary valve
RA	Right atrium
RLPV	Right lower pulmonary vein
RUPV	Right upper pulmonary vein
RV	Right ventricle
RVH	Right ventricular hypertrophy
RVIDd	Right ventricular cavity diameter in diastole
RWMA	Regional wall motion abnormality
RVOT	Right ventricular outflow tract
RVOTd	Right ventricular outflow tract dimension
s'	Lateral and/or septal systolic annular velocity
SAM	Systolic anterior motion
STJ	Sinotubular junction
SVol	Stroke volume
TAPSE	Tricuspid annular plane systolic excursion
TR	Tricuspid regurgitation
TV	Tricuspid valve
Vmax	Maximum velocity
VSD	Ventricular septal defect
VTI	Velocity time integral