NON-COMPACTION OF VENTRICULAR MYOCARDIUM, CLINICAL AND ECHOCARDIOGRAPHIC FEATURES OF 8 CASES

SKM Ali, J duPlessis, MJ GodmanKing Abdulaziz Cardiac Center, Riyadh, Kingdom of Saudi Arabia

Non-compaction of the ventricular myocardium (NVM) is a rare cardiomyopathy characterized by prominent trabeculations and deep intertrabecular recesses. In this study 8 cases of NVM were followed prospectively. The age of presentation ranged from birth to 10 months. Male to female ratio was 1:3. Clinical presentation was variable; one asymptomatic infant (patient 1) was identified incidentally because of associated patent ductus arteriosus. One infant (patient 2) presented with mild congestive heart failure attributed to associated multiple ventricular septal defects and three patients with isolated NVM (patients 3, 4 and 5) presented with heart failure. In a further three patients (patients 6, 7 and 8) NVM was associated with complex cyanotic congenital heart disease. In all patients diagnosis was confirmed echocardiographically by calculating a ratio of non-compacted to compacted layer thickness of 2 or more. In patients 1 and 2 the ventricular function was normal while it was impaired in the others. Short-term outcome reflected the heterogeneous nature of the disease; patient 1 is doing well with a normal ventricular function, patient 2 showed clinical improvement of congestive heart failure. Patient 3 died with severe myocardial dysfunction at the age of 7 days. Patients 4 and 5 are alive with severely impaired function. Patient 6 died with ventricular arrhythmia following a Blalock-Taussing shunt insertion. Patients 7 and 8 are alive with impaired myocardial function.

NVM may not be as rare as is thought. It should be considered in infants presenting with either congenital heart disease or cardiomyopathy in whom the echocardiographic features suggest excessively prominent trabeculations with or without left ventricular dysfunction.

PREDICTION OF SYMPTOM ONSET IN AORTIC STENOSIS: BASELINE AND SERIAL ECHOCARDIOGRAPHY IN 97 PATIENTS

P Das, H Rimington, J ChambersValve Study Group, Guy’s and St Thomas’ Hospitals, London, UK

Background: It remains unclear which echocardiographic variables are of prognostic significance in asymptomatic aortic stenosis (AS). This prospective study aimed to identify variables from baseline and serial echocardiography that differed in patients who subsequently became symptomatic.

Methods: 97 patients aged 65 years (range 27–81) were studied. All denied symptoms and had normal left ventricular systolic function. A transthoracic echocardiographic study was made at baseline and six monthly intervals. Mean pressure drop was calculated using the Bernouilli formula and effective orifice area (EOA) from the continuity equation. Patients were reviewed and questioned for symptoms every six months.

Results: Mean follow up was 20 months (range 5–30). 80 patients had 2 or more echocardiograms. 24 patients developed symptoms and 73 remained asymptomatic. Peak aortic velocity and mean resistance were significantly greater for patients developing symptoms whilst EOA and left ventricular long axis excursion (LAE) were lower. There were no differences in rate of change of peak aortic velocity or EOA.

Conclusion: Baseline effective orifice area, peak aortic velocity, mean resistance and left ventricular long axis function were significantly different in patients with AS who became symptomatic. However, the rate of change of peak velocity and EOA did not have prognostic significance.

CARDIAC CAVITY SIZE INDEX TO DIAMETER OF THE SUBAORTIC ANNULUS

B Jiang, C Gale, K GodfredMRC Environmental Epidemiology Unit, Southampton General Hospital, Southampton, UK

Introduction: The aortic velocity integral remains constant during growth in childhood. This suggests that the aorta grows to accommodate the change in cardiac output necessary for the metabolic demands of the body. It may be logical to use the size of the aorta as a physiological index in place of body surface area.

Methods: We therefore assessed aortic size and left ventricular structure in 215 healthy children (112 boys and 103 girls), aged between 8 and 9 years. Echocardiograms were performed with an Acuson 128 XP system using a 3.5 MHZ probe. Cavity dimensions were averaged over 5 consecutive cardiac cycles using the ASE convention.

Results: There were wide differences in height (115–157 cm) and weight (20.0–55.8 kg). Left atrial diameter ranged between (LA 1.60–3.09 cm) and left ventricular diastolic diameter between (LVDd 3.35–4.83 cm). Both left atrial and left ventricular diameters were correlated with body surface area: LA 9=(r=0.502, p<0.001), LVDd (r=0.632, p<0.001). There were similar correlation with subaortic annulus diameter: LA (r=0.365, p<0.001), LVDd (r=0.530, p<0.001). The correlations with body surface area were no longer apparent after indexing the raw dimension to subaortic annulus diameter: LA/annulus (r=0.109, p=0.10), LVDd/annulus (r=0.144, p=0.05).

Conclusion: Indexing to subaortic annulus diameter is a simple and convenient method of adjusting cardiac chambers for body size during childhood and this may be a clinically useful alternative to indexing to body surface area.

BIVENTRICULAR PACING: THE EFFECTS OF LEAD POSITION AND PACING INTERVALS ON CARDIAC PERFORMANCE

RE Lane, AWC Chow, I Wright, RJ Schilling, NS Peters, J Mayet, DW DaviesSt. Mary’s Hospital and Imperial College School of Medicine, London, UK

Introduction: In patients with heart failure (HF) and left bundle branch block (LBBB), left ventricular (LV) asynchrony contributes to systolic impairment. Biventricular pacing (BVP) is now an established treatment, however, the optimal LV lead position and interventricular pacing interval (IPI) have yet to be established. Tissue Doppler imaging (TDI) was used to assess the effects of different LV lead positions and IPIs on regional LV systolic function.

Methods: 9 patients (age 74±7years; 4 with ischaemic heart disease and 5 with dilated cardiomyopathy) with chronic HF (NYHA III–IV, LVEF <30%) and LBBB (QRS 169±26ms) were studied. Pulsed wave TDI were measured at the level of the mitral valve annulus at baseline and during BVP. Temporary BVP from RV and 2 different LV positions at 5 IPIs were examined: RV-LV intervals were set at +80, +40, 0, −40 and −80ms with reference to RV pacing. LV pacing was performed from the lateral (n=9) and the inferoposterior walls (n=7).

Results: Systolic velocities for septum at RV-LV 0, −40 and −80ms and posterior wall at −80ms were significantly increased from baseline with both LV pacing sites. Neither LV pacing site nor IPI significantly altered lateral or RV wall systolic velocities.

Conclusion: During BVP, septal and posterior wall systolic velocities are increased irrespective of LV pacing site. Greatest improvement in LV systolic function occurs when LV precedes RV pacing.

ECHOCARDIOGRAPHIC CHARACTERISTICS OF DYSSYNCHRONY CAUSED BY LEFT BUNDLE BRANCH BLOCK IN PATIENTS UNDERGOING CARDIAC RESYNCHRONISATION PACING

DT Chin, J Allen, JE DaviesUniversity Hospitals of Leicester NHS Trust, Leicester, UK

Background: There is convincing evidence that cardiac resynchronisation pacing (CRT) reduces morbidity in patients with class III/IV heart failure, left ventricular ejection (LVEF) ≤35% and left bundle branch block (LBBB), width ≥150 ms. CRT improves cardiac efficiency by improving atrial priming, reducing mitral regurgitation and LV volumes, increasing LVEF and forward cardiac output. However, up to one third of patients selected by the above criteria do not respond as measures of electrical delay may not identify the mechanical abnormality that can be reversed by CRT. We propose that routine echo may aid selection by identifying mechanical dyssynchrony in LBBB.

Methods: We studied the echo characteristics of LBBB in 16 heart failure patients indicated for CRT (group A) and 15 patients investigated for chest pain (group B). LV wall motion score index (WMSI), the average score (1=normokinesis, 2=hypokinesis, 3=akinesis, 4=dyskinesis) of 16 LV segments, was used to detect the dyskinesis associated with LBBB. LVEF (Method of disks) in the 4 and 2 chamber views were obtained to study regional contractile dyssynchrony. Doppler cardiac output (CO) and interventricular pre-ejection delay were measured.

Results: Group A patients had mean LV diastolic diameters of 6.4±1.1 cm and significantly worse WMSI, LVEF and CO than group B. In these CRT patients, interventricular dyssynchrony was detected as left sided pre-ejection delays of 50±23 ms. Atrioventricular dyssynchrony was manifest as presystolic mitral regurgitation in 56% and as a uniphasic mitral Doppler inflow due to e/a fusion in 50%. LV dyssynchrony was seen with an average of 6.7±3.7 LV segments showing paradoxical contraction, particularly in the 4 and 3 chamber views. 14/16 group A patients, compared to 3/15 group B patients exhibited significant paradoxical LV contraction.

Conclusion: Routine echo can detect mechanical evidence of interventricular, atrioventricular and LV evidence of dyssynchrony associated with LBBB.

THE DETECTION OF SYMPTOMATIC LEFT VENTRICULAR INTRACAVITY GRADIENTS DURING DOBUTAMINE STRESS ECHOCARDIOGRAPHY

DG Platts, KM Rance, MJ MonaghanCardiology Department, King’s College Hospital, London, UK

Dobutamine stress echocardiography (DSE) is a routine investigation to assess for the presence of reversible myocardial ischaemia. However, there are instances where the patient’s symptoms are reproduced despite the absence of any wall motion abnormality. It is in this subgroup of patients that left ventricular cavity dynamics were further assessed in response to stress. 59 patients had a DSE over a 5-month period, utilising a graded DSE protocol. 18 were positive and 41 negative for wall motion abnormalities. In 5 out of 20 patients with reproduction of their symptoms but normal wall motion, marked systolic cavity obliteration was noted at peak stress. In these patients, continuous wave Doppler (CW) was performed to evaluate intracavity gradients (ICG) or for left ventricular outflow tract obstruction (LVOTO). CW monitoring was also continued during recovery. Baseline characteristics of these 5 patients: 2 male, 3 female, av. age 54 (range 35-65), LVH-severe (2), moderate (1), mild (1), normal (1). Peak ICG range 50-143 mmHg (mean 119). SAM present in 3/5. Symptoms: chest pain (2), dyspnoea (3). All 5 had systolic cavity obliteration resulting in a significant ICG and/or LVOTO. These features resolved fully during recovery in all patients. These cases demonstrate the anatomical (LV wall thickness and cavity size) and physiological (ICG and SAM of MV) parameters that can be assessed during a DSE that may account for the patient’s symptoms if wall motion is normal. In 25% of patients (i.e. 5 out of 20) with a negative but symptomatic DSE, these haemodynamic anomalies were identified. There appeared to be no correlation between the presence and degree of LVH and the development or degree of any ICG or LVOTO. We recommend the monitoring such left ventricular dynamics in these patients.

MODERATE OR SEVERE AORTIC STENOSIS? DOBUTAMINE STRESS ECHOCARDIOGRAPHY IN PATIENTS WITH MILD SYMPTOMS

P Das, H Rimington, S Gallagher, J ChambersValve Study Group, Guy’s and St Thomas’ Hospitals, London, UK

Background: Distinguishing moderate from severe aortic stenosis (AS) in patients with mild symptoms can be difficult. Previous studies suggested that dobutamine stress echocardiography could help identify severe AS. We compared resting measures and the mean pressure drop/flow slope (PFS) to surgical findings.

Method: 25 patients with isolated AS were studied because of mild symptoms and uncertainty over the severity of stenosis. Resting transthoracic echocardiography was repeated. Dobutamine was infused in increments of 5 mcg/kg/min to a maximum of 40 mcg/kg/min. Doppler studies were repeated at each stage. Transaortic flow at each stage was plotted against mean pressure drop and the PFS derived from the linear regression equation. The anatomic degree of stenosis on visual inspection at surgery was recorded where noted as moderate or severe.

Results: Resting peak transaortic velocity was 3.5±0.7 m/s, mean pressure drop 29.7±12.7 mmHg and effective orifice area (EOA) 0.9±0.2 cm². Resting left ventricular function was normal in all cases. There were no complications during dobutamine stress. There was a linear mean pressure/flow slope in 22 cases, mean 0.14 mmHg/mls⁻¹. 17 patients were subsequently listed for surgery and 14 underwent valve replacement, of which 9 were described as having severe and 4 moderate stenosis. Patients with surgically severe vs moderate stenosis had similar peak transaortic velocity (3.8 vs 3.5m/s, p=0.6), mean pressure drop (34.0 vs 28.3 mmHg, p=0.4) and resting EOA (0.78 vs 0.95 cm², p=0.18). PFS was significantly greater in severe stenosis (0.19 vs 0.06 mmHg/mls⁻¹, p=0.015).

Conclusion: This small study suggests that dobutamine stress echocardiography can be used in management of patients with apparently moderate aortic stenosis and equivocal symptoms. A PFS of >0.1 mmHg/mls⁻¹ reliably identified patients with anatomically severe stenosis at surgery.

BRAIN NATRIURETIC PEPTIDE IS A USEFUL MARKER OF LEFT VENTRICULAR DYSFUNCTION FOLLOWING MITRAL VALVE REPAIR

A Macnab, NP Jenkins, C Reeves, BG Keevil, BJ Bridgewater, TL Hooper, SG RayWythenshawe Hospital, Manchester, UK

Background: Following successful mitral valve repair surgery, even mild left ventricular (LV) dysfunction carries a poor prognosis. One of the most powerful predictors of this is reduced pre-operative ejection fraction (EF). We assessed the role of baseline Brain Natriuretic Peptide (BNP) as an additional marker of LV dysfunction 6 months following mitral repair.

Methods: 33 patients had pre-operative N-terminal pro-BNP measured using a commercial enzyme-linked immunosorbent assay. All patients had severe mitral regurgitation (Regurgitant fraction >55%) due to degenerative valve disease. Patients with hypertension, previous myocardial infarction, renal or hepatic disease were excluded. Patients who had peri-operative infarction or unsuccessful repair as evaluated by a pre-discharge echocardiogram were also excluded. LV EF was calculated by biplane method of discs immediately prior to surgery and repeated after 6 months. An EF of <50% was considered significant.

Results: Baseline patient data was as follows: mean (SD) age 62 (13) years, 73% sinus rhythm and 3 patients with concomitant coronary disease. Mean (SD) BNP was 255 (236) fmol/ml. Post-operative EF was significantly less than at baseline {mean(SD) 60(8)% vs 52(11)% respectively; p<0.001}. At 6 month follow-up 1 patient died and 11 had an EF<50%. In the post-operative LV dysfunction group, baseline BNP concentration was significantly greater and pre-operative EF was significantly lower {mean(SD) 420(298) vs 169(148) fmol/ml for BNP, p=0.021 and 62(1)% vs 55(3)% for EF, p=0.039}. Log(BNP) was inversely associated with post-operative EF, independently of age and baseline EF in a multiple regression model (R² =0.468, p=0.047).

Conclusion: BNP has incremental value in the prediction of LV dysfunction following successful mitral repair surgery for degenerative valve disease.

OBJECTIVE ASSESSMENT OF PULMONARY REGURGITATION IN REPAIRED TETRALOGY OF FALLOT PATIENTS

ZI Khan, GA Wharton, GJ WilliamsYorkshire Heart Centre, Leeds, UK

Introduction: The presence and severity of pulmonary regurgitation (PR) in repaired tetralogy of Fallot (rTOF) patients has been shown to be a factor in the reduced exercise performance experienced by these patients. Patients with restrictive right ventricular (RV) physiology have reduced PR therefore improved exercise haemodynamics. Apart from MRI there is no easily accessible non-invasive method of assessing the severity. We therefore looked at a group of adult rTOF patients with a view to defining a simple measurement to assess severity.

Method: All subjects underwent echocardiography prior to cardiopulmonary exercise testing. Images were digitally stored & analysed off line. Peak PR velocity (v), acceleration time (ac.t), deceleration time (dt), deceleration slope (dv/dt) and pressure half time (p1/2t) were measured & averaged from 3 cardiac cycles. Restrictive (R-) RV physiology was defined as antegrade flow in the pulmonary artery coinciding with atrial systole.

Results are expressed as mean (±SD). 26 rTOF subjects (31.08±9.42yrs) were investigated of which 13 had R-RV physiology. Peak PR v was reduced in the R-RV group (1.60±0.59 m/s v 1.98±0.33 m/s, p<0.04). There was no significant difference in dt, dv/dt or p1/2t between the groups. Peak PR v correlated with peak oxygen consumption (VO₂) (r=−0.4, p<0.04) & cardiac reserve (r=−0.5, p<0.02). dv/dt correlated with exercise time (r=−0.5, p<0.01), peak VO₂ (r=−0.5, p<0.02), peak cardiac output (r=−0.6, p<0.01) & cardiac output reserve (r=−0.7, p<0.01). dt correlated with peak cardiac output (r=0.4, p<0.05) and p1/2t with rest & percentage predicted heart rate (r=−0.6, p<0.01 & r=−0.4, p<0.05 respectively).

Conclusion: The reduction in peak PR v along with the negative correlation with peak VO₂ & cardiac reserve confirm the superior exercise haemodynamics experienced by the restrictive group. Deceleration slope and pressure halftime are independent of RV diastolic physiology yet both correlate significantly with exercise haemodynamics. This may prove an invaluable measurement in the continual assessment of these patients.

THE IMPACT OF DOBUTAMINE STRESS ECHOCARDIOGRAPHY (DSE) RESULTS ON PATIENT MANAGEMENT: DOES A POSITIVE DSE LEAD TO SUBSEQUENT INTERVENTION?

J Byrne, D Platts, K Rance, J Hancock, M MonaghanKing’s College Hospital, London, UK

DSE is a well-established technique for detecting reversible ischaemia and viable myocardium. However, the impact of a DSE result on patient management is less well documented. We performed a retrospective analysis of all patients undergoing a DSE over a 14-month period (April 2000-June 2001) at our institution. This was facilitated by utilising the Enconcert digital echocardiography storage system coupled with the search program Crystal Reports. In all patients undergoing a DSE, a search of the angiography database was also performed. In those not having angiography after a positive DSE, case notes were reviewed. 114 DSE were performed. 55 positive, 59 negative. Of the 55 positive DSE, 44 had angiography – 10 were part of a PMR trial and not included in this analysis. The DSE correctly predicted the territory of significant angiographic stenosis in 21/34. A positive DSE led to percutaneous intervention on the correctly identified culprit lesion in 16/21 (76%). Of the remaining 13 positive DSE, there was discordance between the DSE predicted territory and angiographic findings in 8 and 5 (14.7%) had a normal angiogram. 9 had a negative DSE with subsequent angiography – 5 were normal, 4 had significant single vessel disease (SVD) but no intervention was performed in light of the DSE result. A positive DSE led to revascularisation (PCI or CABG) in 19/34 (56%). Of the remainder most lesions were considered inappropriate for intervention or no longer clinically indicated. In conclusion, a positive DSE had a significant impact on patient management leading to revascularisation in just over half the cases. Conversely, where the DSE did not detect significant SVD, the result dictated that no intervention was undertaken. Finally, in three quarters of the cases where the DSE confirmed the physiological presence of a lesion, intervention was undertaken to that lesion.

HOW DO AGE AND HEART RATE AFFECT REGIONAL SYSTOLIC AND DIASTOLIC MYOCARDIAL FUNCTION?

B Wasan, R Lane, A Zambanini, R Foale, S Thom, J MayetImperial College and St Mary’s Hospital, London, UK

Background: Tissue Doppler echocardiography (TDE) allows the non-invasive accurate and objective assessment of regional left and right ventricular systolic and diastolic function, enabling subtle changes to be measured. Global left ventricular diastolic function, classically measured by transmitral pulsed wave Doppler flow, reduces with increasing age. It is not known whether this occurs uniformly across different myocardial territories. Systolic velocities are not thought to be normally influenced by the ageing process but do increase with heart rate.

Methods: 60 volunteers aged 20 to 80 were studied. All had normal ECGs and 2D echocardiograms and were not on any medications. Pulsed wave TDE images were obtained from the apical echocardiographic window and systolic (S) and early diastolic (E) myocardial velocities were measured at the septal (sep), lateral (lat) and inferior (inf) aspects of the mitral valve annulus and the free wall of the tricuspid annulus (RV).

Results: Heart rates varied between 55 and 100 beats per minute. Correlation coefficients (r) for the relationship between S and E velocities with age: sep(S) r=−0.40, p=0.003; sep(E) r=−0.73, p<0.0001; lat(S) r=−0.26, p=0.06; lat(E) r=−0.71, p<0.0001; inf(S) r=−0.25, p=0.06; inf(E) r=−0.79, p<0.0001; RV(S) r=0.10, p=0.5; RV(E) r=−0.38, p=0.0039. Correlation coefficients (r) for regional velocities as a function of heart rate in normals: sep(S) r=0.5, p<0.0001; sep(E) r=0.06, p=0.6; lat(S) r=0.21, p=0.1; lat(E) r=0.13, p=0.3; inf(S) r=0.25, p=0.06; inf(E) r=0.07, p=0.6; RV(S) r=0.42, p=0.001; RV(E) r=0.16, p=0.2.

Conclusions: In contrast to current thinking, left ventricular systolic function does in fact subtly decrease with normal ageing. This reduction is not apparent in the right ventricle. Hence, in the assessment of regional systolic function, both age and heart rate must be taken into account. Normal heart rate variation does not influence regional diastolic velocities and the changes seen with age appear to occur in a uniform fashion.

DISTURBANCE OF CARDIAC AND LARGE ARTERY FUNCTION IN HEART FAILURE.

SL Cunningham¹, KH Parker², J Mayet¹, RA Foale¹, SAMcG Thom¹, AD Hughes¹¹St Mary’s Hospital, London,²Physiological Flow Studies Unit, Imperial College, London, UK

It has been proposed that altered pressure wave reflection, due to abnormalities of large artery function, could contribute to impaired cardiac function in heart failure (HF). Wave intensity analysis (WIA) is a recently described non-invasive technique that provides information on the working state of the heart, wave reflections, and arterio-ventricular interaction. Wave intensity is a measure of the energy carried by a wave and is the product of instantaneous changes in pressure and flow velocity at any arterial site. We used WIA to investigate the possibility of altered wave reflection and to further understand the haemodynamic changes that occur in HF. 29 patients with HF (NYHA class II–III, mean EF 35%) (60±9yrs) were compared to 29 age-matched subjects (60±9yrs) with normal systolic function (N). Brachial blood pressure, carotid arterial pressure (P) and flow velocity (U) were measured by sphygmomanometry, tonometry and pulsed wave Doppler respectively. The intensities of forward and backward waves and carotid pulse wave velocity (c) were calculated. Data are means ± SD, p was calculated by Student’s t-test. P was lower in the HF group [129±21 (N); 120±24mmHg (HF); p=0.10]. c did not differ [13.6±5.5 (N); 13.2±6.3ms-1 (HF)], suggesting that the elastic properties of the artery were unchanged. Peak U was significantly reduced in the heart failure group [0.70±0.15 (N); 0.56±0.17ms-1 (HF), p=0.006]. Ventricular wave power was dramatically reduced in HF [29.2±9.8 (N); 15.4±7.7mWm-2 (HF); p<0.00001], as was wave work [232±80 (N); 124±66 Jm-2 (HF); p<0.00001]. Wave reflection from the head [13.3±7.5 (N); 17.5±11.7% (HF), p=0.08] and the body [1.5±1.7 (N); 5.4±6.1% (HF), p=0.001] were increased in the HF group. Heart failure is associated with a dramatic impairment in the ability of the heart to generate pressure waves. In addition wave reflection is increased, consistent with widespread vasoconstriction. This places an additional load on the ventricle that may further impair its function. WIA is a novel, simple way of providing important haemodynamic information in heart failure.