Antoinette Kenny

Assessment of mitral regurgitation

Mitral regurgitation (MR) is the most commonly encountered valve lesion in modern clinical practice.1 The range of pathologies producing regurgitant mitral valve dysfunction is broad (table 1) and the condition may be met in virtually any medical speciality. As echocardiography is the most widely available cardiac imaging modality, it is the technique which is routinely used to assess patients with suspected or known MR. While echo-Doppler is an excellent technique for detecting the presence of MR and defining the underlying pathological cause, assessing and/or quantifying the severity of the leak by echocardiography can at times be difficult. This reflects the fact that regurgitant flow through the mitral valve is a complex and dynamically changing process which may be impossible to characterise fully using a two dimensional imaging modality. Nevertheless, if MR is discovered on an echocardiographic examination it is extremely important to make an assessment of severity as this will be required to guide the patient’s subsequent management. View this table: Table 1 Causes of mitral regurgitation What therefore is the optimal way to assess the severity of MR? Do potentially cumbersome quantitative echo-Doppler methods for calculation of regurgitant orifice area, regurgitant volume or regurgitant fraction add anything to a subjective assessment of severity (mild, moderate, severe) carried out by an experienced sonographer? Should already busy and overburdened echocardiography staff be stretching themselves further to perform complex quantitative techniques on MR patients? The answer is probably that detailed quantification is not necessary in the majority of patients. Non-cardiologists need to know whether the regurgitation is significant enough to warrant further cardiological assessment; this does not require detailed quantitative information. Cardiologists use echo-Doppler grading of regurgitation severity in conjunction with patient symptoms and signs and occasionally invasive haemodynamic information to make decisions on the need for and timing of mitral valve surgery. In the majority …

Profiles of coronary blood flow velocity in patients with aortic stenosis and the effect of valve replacement: a transthoracic echocardiographic study.

OBJECTIVE--To report the first non-invasive assessment by transthoracic Doppler echocardiography of coronary blood flow in patients with aortic stenosis and of the effects of valve replacement. DESIGN--High frequency transthoracic Doppler echocardiography was used to examine resting phasic flow in the left anterior descending coronary artery before and after replacement of the aortic valve in awake, unsedated patients with pure aortic stenosis and normal coronary arteries. SETTING--A tertiary referral cardiothoracic centre. METHODS--Eleven patients with pure aortic stenosis and normal coronary arteries (six men, five women, mean (range) age 69 (50-82) years), were studied the day before and 1 week after replacement of the aortic valve. These patients were selected from a cohort of 15 due to ease of imaging of the left anterior descending coronary artery. Seven had a history of angina. Haemodynamics, peak transvalvar aortic gradient, left ventricular mass index, ventricular dimensions, and profiles of coronary flow velocity were measured. Profiles of coronary flow velocity were also measured in a control population of 10 normal subjects (five men, five women, mean (range) age 58 (34-66) years). RESULTS--The control population showed forward flow throughout systole, but reversed early systolic flow (mean velocity 20.6 (3.6) cm/s) was seen in six patients with aortic stenosis. Only three of these patients had a clinical history of angina. Peak and mean systolic and diastolic forward flow velocities were not significantly different in the control group and in patients with aortic stenosis. The time from the start of systole to the onset of forward systolic flow was significantly longer in patients with aortic stenosis than in the control population (185 (8.5) v 85 (10) ms, p < 0.01). The time from the onset of diastolic flow to peak diastolic velocity was also significantly longer in the aortic stenosis group (146 (16) v 74 (13) ms, p < 0.01). These abnormalities in profiles of coronary flow were reversed by replacement of the aortic valve. There was no correlation between changes in flow profiles in patients with aortic stenosis and preoperative clinical history, transvalvar gradient, left ventricular mass index, or ventricular dimensions. CONCLUSIONS--Coronary flow profiles in patients with aortic stenosis were characterised by reversed early systolic flow and delayed forward systolic flow and attainment of peak diastolic velocity. Reversal of these abnormalities by replacement of the aortic valve may reflect altered left ventricular and aortic haemodynamics and contribute to the relief of angina when left ventricular hypertrophy persists. Further studies may correlate abnormalities of coronary flow with preoperative clinical and haemodynamic state.

How to quantitate valve regurgitation by echo Doppler techniques

Echo Doppler techniques have revolutionised the non-invasive investigation of valvular heart disease and have become widely accepted and used as part of modem clinical cardiology. There is no single method that provides an entirely accurate quantitative assessment of the severity of valve regurgitation, and the complex interaction of anatomic and haemodynamic variables can add to these potential difficulties. Although cardiac ultrasound techniques do provide important clinical information in patients with valve regurgitation it is very important that the results are interpreted with a knowledge not only of the clinical findings but also of the advantages and limitations of cardiac ultrasound. This article attempts to provide a practical perspective of the current value of echo Doppler techniques in the assessment of valve regurgitation and to provide an. insight into the relative merits of individual methods of quantitation.

Prevalence of left ventricular dysfunction in a UK community sample of very old people: the Newcastle 85+ study

Objective Heart failure (HF) prevalence rises sharply among those aged 85 years and over. Previous population based echocardiographic studies of left ventricular (LV) dysfunction, the substrate for HF, have included only small numbers in this age group. We used domiciliary echocardiography to estimate the prevalence of LV systolic and diastolic dysfunction in 87–89 year olds and the proportion remaining undiagnosed. Design Cross sectional analysis of data from Newcastle 85+ Study. Setting Primary care, North-East England. Participants 376 men and women aged 87–89 years. Measures Domiciliary echocardiography was performed and LV systolic and diastolic function was graded. The presence of limiting dyspnoea was assessed by questionnaire. Previous diagnoses of HF were abstracted from general practice (GP) records. Results 32% of participants (119/376) had LV systolic dysfunction (ejection fraction (EF) ≤50%) and a further 20% (75/376) had moderate or severe LV diastolic dysfunction with preserved EF. Both echocardiographic assessment of LV function and dyspnoea status were available in 74% (278/376) of participants. Among these participants, limiting dyspnoea was present in approximately two thirds of those with significant (systolic or isolated moderate/severe diastolic) LV dysfunction. 84% (73/87) of participants with significant LV dysfunction and limiting dyspnoea did not have a pre-existing HF diagnosis in their GP records. Overall, 26% (73/278) of participants with both echocardiographic and dyspnoea data had undiagnosed, symptomatic, significant LV dysfunction. Conclusion Significant systolic and diastolic LV dysfunction is much commoner in community dwelling 87–89 year olds than previous studies have suggested. The majority are both symptomatic and undiagnosed.

Dobutamine Stress Echocardiography: Improved Endocardial Border Definition and Wall Motion Analysis with Tissue Harmonic Imaging

BACKGROUND We performed a study to determine whether tissue harmonic imaging (THI) facilitates wall motion analysis at rest and whether these benefits extend through the stages of a dobutamine stress echocardiography (DSE) study. We also assessed the impact of THI on the feasibility of DSE in technically difficult patients. Finally we tested the hypothesis that THI by improving endocardial border definition (EBD) could enhance the interobserver agreement between trainees and experienced operators for interpreting DSE studies. METHODS Twenty unselected patients underwent DSE by standard protocol. Parasternal and apical views were obtained with the use of fundamental mode (FND) and THI at baseline, low dose, and peak stress. Segmental EBD was characterized as 1 to 4 (1 = excellent) and segmental wall motion was characterized as 1 to 4/x (1 = normal, x = unable to interpret) by a consensus of 2 experienced observers. A trainee in stress echocardiography independently scored all segments, and these results were compared with the consensus of the experienced readers. RESULTS EBD improved with THI in 26 +/- 6.7 of 48 segments per patient (54%, 95% confidence interval [CI] 0.40 to 0.68) and deteriorated with THI in only 2 +/- 2.7 (4%, 95% CI 0 to 0.09). Of the total of 48 segments per patient, a mean of 10 +/- 5.7 (21%, 95% CI 0.10 to 0.31) were of inadequate quality to be interpreted for wall motion on FND, and this changed to 4 +/- 3.4 (6%, 95% CI 0.06 to 0.12) on THI (P <.001). EBD improved in a similar degree in all DSE stages 53%, 54%, and 53% for rest, low dose, and peak stress, respectively. Six of the 20 study patients were deemed unsuitable for DSE on FND, and all were changed to suitable subjects on THI. Of the 205 segments deemed unsuitable for interpretation on FND, 140 (68%) were of the anterior and lateral walls of the LV. Improvement with THI was also more prominent on these walls. The mean coefficient of agreement (kappa) for wall motion analysis was 0.82 +/- 0.14 on FND and improved to 0. 92 +/- 0.09 on THI (P <.001). CONCLUSIONS THI dramatically improves EBD and the ability to confidently score segmental wall motion. Interobserver agreement is also significantly enhanced. These benefits extend to the peak stage of a DSE study. Routine use of THI may enhance the diagnostic accuracy of DSE and extend its application to technically difficult patients previously deemed unsuitable.

Accuracy of real-time, three-dimensional Doppler echocardiography for stroke volume estimation compared with phase-encoded MRI: an in vivo study.

To the editor: Accurate measurement of cardiac output (CO) is important in clinical medicine. Current methods of calculation use two-dimensional echocardiography and ventricle volumetry or spectral Doppler pulse wave. Phase-encoded MRI is an accurate technique for volume assessment; however, is not suitable for many clinical situations, such as in those who are critically ill. Previous work by our group has shown that real-time, three-dimensional Doppler echocardiography (RT3DDE) can accurately compute stroke volume (SV) and CO in an animal model against a “gold standard” of aortic flow probe using the left ventricular outflow tract colour Doppler signal,1 and this technique can be used in patients transthoracically.2 3 We tested the accuracy of RT3DDE of the left ventricular outflow tract for calculation of SV in a series of patients and healthy volunteers against a “gold standard” of phase-encoded MRI. Two patients and 12 healthy volunteers took part in the study. The patients were undergoing MRI as part of their clinically indicated investigations for cardiac disease (both patients for aortic coarctation). All subjects gave written informed consent in accordance with the local Institutional Review Board. The Philips Live 3D 7500 Sonos echocardiography system with a 3000-element 2–4 MHz xMATRIX transthoracic probe (Philips Medical Systems, Andover, Massachusetts, USA) was used for imaging. Subjects underwent echocardiography immediately before MRI. Between three and five ECG-gated, three-dimensional colour Doppler volumes were acquired from …

Dobutamine stress echocardiography for the detection of myocardial viability in patients with left ventricular dysfunction taking β blockers: accuracy and optimal dose

Objective: To assess the accuracy of dobutamine stress echocardiography (DSE) and the optimal dose of dobutamine to detect myocardial viability in patients with ischaemic left ventricular (LV) dysfunction who are taking β blockers, using the recovery of function six months artery revascularisation as the benchmark. Patients: 17 patients with ischaemic LV dysfunction (ejection fraction < 40%) and chronic treatment with β blockers scheduled to undergo surgical revascularisation. Setting: Regional cardiothoracic centre. Methods: All patients underwent DSE one week before and resting echocardiography six months after revascularisation. A wall motion score was assigned to each segment for each dobutamine infusion stage, using the standard 16 segment model of the left ventricle. The accuracy of DSE to predict recovery of resting segmental function was calculated for low dose (5 and 10 μg/kg/min) and for a full protocol of dobutamine infusion (5 to 40 μg/kg/min). Results: Of the 272 segments studied, 158 (58%) were dysfunctional at rest, of which 79 (50%) improved at DSE and 74 (47%) recovered resting function after revascularisation. Analysis of results with a low dose showed a significantly lower sensitivity and negative predictive value than with a full protocol (47% v 81%, p < 0.001 and 65% v 82%, p < 0.05, respectively). The accuracy in the full protocol analysis was comparable with that reported in patients no longer taking β blockers but was significantly lower than that in the low dose analysis (78% v 66%, p < 0.001). Conclusions: Findings suggest that β blocker withdrawal is not necessary before DSE when viability is the clinical information in question. However, a completed protocol with continuous image recording is required to detect the full extent of viability.

Accuracy of 3-dimensional color Doppler-derived flow volumes with increasing image depth

We and others have reported on the use of digital color Doppler sonography from real‐time 3‐dimensional (3D) echocardiography and its use in accurately calculating cardiac flow volumes, namely stroke volume (SV) and, hence, cardiac output. However, in some patients, image depth is higher than average, and this may affect the accuracy of volume calculation. We sought to investigate the impact of image depth and the accompanying change in signal strength, spatial resolution, and pulse repetition frequency on the accuracy of SV calculation from 3D color Doppler data in an in vitro model.

Detection of myocardial viability by dobutamine stress echocardiography: incremental value of diastolic wall thickness measurement

Objective: To assess the diagnostic accuracy of baseline diastolic wall thickness (DWT) alone and as an adjunct to dobutamine stress echocardiography (DSE) for prediction of myocardial viability in patients with ischaemic left ventricular (LV) dysfunction, with the recovery of resting function after revascularisation as the yardstick. Patients: 24 patients with ischaemic LV dysfunction (ejection fraction < 40%) scheduled for surgical revascularisation. Setting: Regional cardiothoracic centre. Methods: All patients underwent DSE before and resting echocardiography six months after revascularisation. DWT was measured in each of the 16 LV segments. A receiver operating characteristic (ROC) and a multi-ROC curve were generated to assess the ability of DWT alone and in combination with DSE to predict myocardial viability. Results: DWT > 0.6 cm provided a sensitivity of 80%, a specificity of 51%, and a negative predictive value of 80% for the prediction of viability in akinetic segments. DSE had an excellent specificity (92%) but a modest sensitivity (60%) in akinetic segments. A combination of improvement at DSE or DWT > 0.8 cm improved sensitivity (90% v 60%, p < 0.001) and negative predictive value (92% v 78%, p  =  0.03) in akinetic segments compared with DSE alone. This was achieved with some loss in specificity (75% v 92%, p  =  0.01) and positive predictive value (71% v 82%, p  =  0.79). Conclusions: DWT measurement may improve the sensitivity of DSE for the detection of myocardial viability. Akinetic segments with DWT > 0.8 cm have a good chance of recovery despite the absence of contractile reserve during DSE. Further testing may be required before excluding myocardial viability in these cases.

Three dimensional colour Doppler echocardiography for the characterisation and quantification of cardiac flow events

The accurate non-invasive quantification of cardiac flow volumes is an important goal in clinical cardiology. Computation of laminar volume flow through the ventricular outflow tracts would allow direct measurement of stroke volume and cardiac output. Grading of valvar regurgitation and follow up of patients with regurgitant lesions may be more accurately performed through calculation of regurgitant volume and fraction, and regurgitant orifice area. While estimates of these parameters can be made by conventional two dimensional (2D) echocardiographic techniques, these methods may be unreliable when applied to complex, dynamic, three dimensional (3D) flow events (table1).1-13 View this table: Table 1 Conventional 2D echo-Doppler cardiac flow quantification methods The advent of three dimensional echocardiography (3DE) provides a solution to this basic limitation. 3DE generates a scan volume (as opposed to a two dimensional scan sector) which produces a three dimensional dataset containing entire cardiac structures.14 15 Surface rendering may then be performed to produce an image with feature contours and depth perspective. Such an approach has proved useful in the representation of complex cardiac structural pathology and in the generation of images which reflect typical “surgeons eye” views of the heart.16 In addition, the 3D dataset may be transected by cut planes orientated in any direction within the volume (“anyplane imaging”). As the entire structure under study is encompassed in the dataset, volume calculations may be made without the need to make geometric assumptions regarding its morphology. A number of studies have confirmed the accuracy of 3D echocardiography for the calculation of cardiac chamber volumes.17-20 3D flow quantitation methods are currently under development and it seems reasonable to assume that these will be superior to the 2D methods listed in table 1. We review these new approaches to the quantification of cardiac flow events and indicate how they may ultimately …