Real-time three-dimensional myocardial contrast echocardiography: is it clinically feasible?

AIMS: Real-time 3D echocardiography (RT3DE) and 2D low mechanical index (LMI), contrast specific, myocardial perfusion imaging are now both accepted techniques. We evaluated the feasibility of an RT3DE LMI implementation in unselected patients. METHODS AND RESULTS: Forty-six patients undergoing contrast enhanced dobutamine stress echo were imaged with novel 3D LMI power modulation software. All patients underwent contrast enhanced 2D and RT3DE acquisitions, in left ventricular opacification (LVO), and LMI perfusion modes. The data sets were evaluated segmentally for wall motion (WM) and myocardial contrast enhancement. Of the 736 evaluated segments, WM could be assessed in 726 (98.6%) of the 2D and 708 (96.2%) 3D segments (P = 0.007). Perfusion could be assessed in 721 (98%) of 2D and 701 (95.2%) of 3D segments (P = 0.006). Six hundred and sixty-one segments had normal WM and thickening in 2D and of these RT3DE demonstrated normal myocardial opacification in 77.2% of basal, 85% of mid, and 91.8% of apical segments. Thirty-four segments were akinetic, with no evidence of perfusion in 2D, and of these RT3DE revealed a perfusion defect in 31 (91%, P = NS). CONCLUSION: LMI RT3DE evaluation of myocardial perfusion is feasible in most segments. It has the potential to accurately locate and possibly quantify perfusion defects.

Impact of 3D echocardiography on grading of mitral stenosis and prediction of clinical events

Background: The mitral valve orifice area (MVOA) is difficult to assess accurately by 2D echocardiography because of geometric assumptions; therefore, 3D planimetry may offer advantages. We studied the differences in MVOA measurements between the most frequently used methods, to determine if 3D planimetry would result in the re-grading of severity in any cases, and whether it was a more accurate predictor of clinical outcomes. Methods: This was a head-to-head comparison of the three most commonly used techniques to grade mitral stenosis (MS) by orifice area and to assess their impact on clinical outcomes. 2D measurements (pressure half-time (PHT), planimetry) and 3D planimetry were performed retrospectively on patients with at least mild MS. The clinical primary endpoint was defined as a composite of MV balloon valvotomy, mitral valve repair or replacement (MVR) and/or acute heart failure (HF) admissions. Results: Forty-one consecutive patients were included; the majority were female (35; 85.4%), average age 55 (17) years. Mean and peak MV gradients were 9.4 (4) mmHg and 19 (6) mmHg, respectively. 2D and 3D measures of MVOA differed significantly; mean 2D planimetry MVOA was 1.28 (0.40) cm2, mean 3D planimetry MVOA 1.15 (0.29) cm2 (P = 0.003). Mean PHT MVOA was 1.43 (0.44) cm2 (P = 0.046 and P < 0.001 in comparison to 2D and 3D planimetry methods, respectively). 3D planimetry reclassified 7 (17%) patients from mild-to-moderate MS, and 1 (2.4%) from moderate to severe. Overall, differences between the two methods were significant (X2, P < 0.001). Only cases graded as severe by 3D predicted the primary outcome measure compared with mild or moderate cases (odds ratio 5.7). Conclusion: 3D planimetry in MS returns significantly smaller measurements, which in some cases results in the reclassification of severity. Routine use of 3D may significantly influence the management of MS, with a degree of prediction of clinical outcomes.

Real-time three-dimensional echocardiography: a novel technique to quantify global left ventricular mechanical dyssynchrony.

BACKGROUND: Left ventricular (LV) mechanical dyssynchrony (LVMD) has emerged as a therapeutic target using cardiac resynchronization therapy (CRT) in selected patients with chronic heart failure. Current methods used to evaluate LVMD are technically difficult and do not assess LVMD of the whole LV simultaneously. We developed and validated real-time 3D echocardiography (RT3DE) as a novel method to assess global LVMD. METHODS AND RESULTS: Eighty-nine healthy volunteers and 174 unselected patients referred for routine echocardiography underwent 2D echocardiography and RT3DE. RT3DE data sets provided time-volume analysis for global and segmental LV volumes. A systolic dyssynchrony index (SDI) was derived from the dispersion of time to minimum regional volume for all 16 LV segments. Healthy subjects and patients with normal LV systolic function had highly synchronized segmental function (SDI, 3.5+/-1.8% and 4.5+/-2.4%; P=0.7). SDI increased with worsening LV systolic function regardless of QRS duration (mild, 5.4+/-0.83%; moderate, 10.0+/-2%; severe LV dysfunction, 15.6+/-1%; P for trend <0.001). We found that 37% of patients with moderate to severe LV systolic dysfunction had significant dyssynchrony with normal QRS durations (SDI, 14.7+/-1.2%). Twenty-six patients underwent CRT. At long-term follow-up, responders demonstrated reverse remodeling after CRT with a significant reduction in SDI (16.9+/-1.1% to 6.9+/-1%; P<0.0001) and end-diastolic volume (196.6+/-17.3 to 132.1+/-13.5 mL; P<0.0001) associated with an increase in LV ejection fraction (17+/-2.2% to 31.6+/-2.9%; P<0.0001). CONCLUSIONS: RT3DE can quantify global LVMD in patients with and without QRS prolongation. RT3DE represents a novel technique to identify chronic heart failure patients who may otherwise not be considered for CRT.

Impact of mitral geometry and global afterload on improvement of mitral regurgitation after trans-catheter aortic valve implantation.

OBJECTIVE: To assess the impact of mitral geometry, left ventricular (LV) remodelling and global LV afterload on mitral regurgitation (MR) after trans-catheter aortic valve implantation (TAVI). METHODS: In this study, 60 patients who underwent TAVI were evaluated by 3D echocardiography at baseline, 1 month and 6 months after procedure. The proportional change in MR following TAVI was determined by examining the percentage change in vena contracta (VC) at 6 months. Patients having a significant reduction of at least 30% in VC were defined as good responders (GR) and the remaining patients were defined as poor responders (PR). RESULTS: After 6 months of TAVI, 27 (45%) patients were GR and 33 (55%) were PR. There was a significant decrease in 3DE-derived mitral annular diameter and area (P = 0.001), mitral valve tenting area (TA) (P = 0.05), and mitral papillary muscle dyssynchrony index (DSI) (P = 0.05) in the GR group. 3DE-derived LVESV (P = 0.016), LV mass (P = 0.001) and LV DSI, (P = 0.001) were also improved 6 months after TAVI. In addition, valvulo-arterial impedance (ZVA) was significantly higher at baseline in patients with PR (P = 0.028). 3DE-derived mitral annular area (ß: 0.47, P = 0.04), mitral papillary DSI (ß: -0.65, P = 0.012) and ZVA (ß: 0.45, P = 0.028) were the strongest independent parameters that could predict the reduction of functional MR after TAVI. CONCLUSION: GR patients demonstrate more regression in mitral annulus area and diameter after significant decrease in high LVEDP and trans-aortic gradients with TAVI. PR patients appear to have increased baseline ZVA, mitral valve tenting and restriction in mitral valve coaptation. These factors are important for predicting the impact of TAVI on pre-existing MR.

Determination of successful reperfusion after thrombolysis for acute myocardial infarction: a noninvasive method using ultrasonic tissue characterization that can be applied clinically.

BACKGROUND: The aim of the present study was to determine the use of cyclic variation in ultrasonic integrated backscatter (IBS), which is reduced in ischemic myocardium, to predict an occluded infarct-related artery (IRA) after thrombolysis for acute myocardial infarction (AMI). This is important, because patency of the IRA 90 minutes after thrombolysis has been shown to predict outcome. METHODS AND RESULTS: One hundred thirteen patients with AMI had peak-to-peak cyclic IBS measured in the myocardial territory supplied by their IRA as well as a remote territory with normal function from the parasternal long- or short-axis view. This analysis took 5 to 10 minutes. Wall motion score index was assessed, and coronary angiography, to determine patency of the IRA, was performed in all patients. Cyclic IBS in the IRA territory was much lower in segments supplied by an occluded IRA (3.3 versus 4.6 dB, P<0.00001). Using a difference in cyclic IBS between infarcted and normal segments of 15% (or 1.5 dB) as a cutoff, the sensitivity, specificity, positive and negative predictive values to determine an occluded IRA were 92%, 75%, 81%, and 89%, respectively. CONCLUSIONS: The difference in cyclic IBS between IRA and remote normal segments, which can be analyzed rapidly, can be used to predict patency of the IRA in patients with AMI. This provides a noninvasive method to determine those patients who may require urgent invasive investigation.

Doppler echocardiographic appearance of cusp tears in tissue valve prosthesis.

Characteristic Doppler echocardiographic abnormalities were noted in five patients with a failing tissue prosthesis shown to have severe regurgitation and no evidence of obstruction. The audio signal was musical in quality and the regurgitant flow pattern was bidirectional and striated. There were 4 to 6 striations in the mitral and 18 in the aortic regurgitant jets per 100 cm/s length of signal. Pulsed Doppler ultrasound localized the jet to the valve in all cases although angiography failed to localize it in one of four cases. At surgery each valve had a tear in or partial disintegration of one cusp whereas the other two cusps were intact, mobile and of normal thickness. The Doppler appearance is thought to be caused by fluttering of the disrupted cusp leading to the shedding of families of vortices in both a retrograde and an orthograde direction. It is suggested that this is likely to be a useful sign for the diagnosis of cusp tears.

Evaluation of myocardial, hepatic, and renal perfusion in a variety of clinical conditions using an intravenous ultrasound contrast agent (Optison) and second harmonic imaging.

OBJECTIVE: To assess the potential of intravenous Optison, a second generation ultrasound contrast agent, and various ultrasound imaging modes to determine myocardial, kidney, and liver perfusion in normal subjects and patients with left ventricular dysfunction or chronic pulmonary disease together with renal or hepatic dysfunction. METHODS: Five normal subjects and 20 patients underwent grey scale echocardiographic imaging of myocardium, kidney, and liver during 505 intravenous injections of Optison. Images were assessed qualitatively by two independent observers and quantitatively using video densitometry to determine the peak contrast enhancement effect. RESULTS: Qualitative analysis showed that intermittent harmonic imaging was superior to either conventional fundamental or continuous harmonic imaging for all organs. Quantitative analysis showed that the peak change in echocardiographic intensity v baseline during continuous harmonic imaging was 11 units for myocardium (p < 0.03), 7 units for kidney (NS), and 14 units for liver (p < 0.05). During intermittent harmonic imaging the peak change was significantly greater, being 33 units for myocardium (p < 0.0001), 24 units for kidney (p < 0.0002), and 16 units for liver (p < 0.001). CONCLUSIONS: Organ tissue perfusion can be demonstrated following intravenous injection of Optison, particularly when used in combination with intermittent harmonic imaging techniques. This contrast agent is effective in a variety of clinical conditions.

Atrial and pulmonary mass: intracardiac thrombus mimicking myxoma on multiplane transesophageal echocardiography.

Transesophageal echocardiography is the method of choice for investigating suspected intracardiac masses. It also plays a valuable role in the detection of central pulmonary artery embolism. We present a case that highlights the use of transesophageal echocardiography for imaging of a mass in the right atrium and the right pulmonary artery.

Transesophageal echocardiography in the detection and surgical management of a papillary fibroelastoma of the mitral valve causing partial mitral valve obstruction.

Primary mitral valve tumors are rare. We describe the transesophageal appearances of a papillary fibroelastoma (Lambl's giant excrescence) of the anterior mitral valve leaflet causing partial mitral valve obstruction. Transesophageal echocardiography proved particularly useful in identifying the limited attachment of the tumor to the anterior mitral valve leaflet and excluding its attachment to the interatrial septum. These features helped to exclude the possibility of the tumor being a left atrial myxoma, the primary differential diagnosis of the lesion. Transesophageal echocardiography enabled the planned surgical option to be mitral valve repair and also allowed intraoperative monitoring to assess the results of the surgical repair.

Aortoatrial fistulae diagnosed by transthoracic and transesophageal echocardiography: advantages of the transesophageal approach.

Aortoatrial fistulae are uncommon, providing a difficult diagnostic challenge both in the clinical diagnosis and in the choice of an imaging modality that fully delineates the abnormal anatomy and flow patterns. This report describes four cases of aortoatrial fistula resulting from three different underlying causes. The fistula communicated with the right atrium in three cases and the left atrium in one. We also describe the diagnostic information obtained during both transthoracic and transesophageal echocardiography and stress that full detail of the abnormal anatomy and shunting could be obtained only with the transesophageal approach, with its improved image quality of the aortic root. No extra information, other than the coronary anatomy, was obtained during aortography in the two patients who underwent cardiac catheterization. Transesophageal echocardiography should, therefore, be the investigation of choice in patients in whom there is a suspicion of aortoatrial shunting after clinical examination and routine transthoracic studies, and it may avoid the need for invasive investigation in these potentially hemodynamically unstable patients.

The value of transthoracic echocardiography during percutaneous balloon mitral valvuloplasty.

Percutaneous balloon mitral valvuloplasty is a standard alternative to surgery in a selected group of patients with symptomatic dominant rheumatic mitral stenosis. With careful transthoracic and transesophageal echocardiographic selection of patients, there is a low complication and high success rate. Echocardiography has also been established as extremely useful in the long-term follow-up of patients. We present four cases that highlight our view that transthoracic echocardiography should be performed during the procedure, after each balloon inflation, and before and after the intervention. In our experience transthoracic echocardiography during balloon mitral valvuloplasty is invaluable in assessing commissural separation, increasing mitral valve area, new mitral regurgitation, and occasional unexpected anatomic sequelae of balloon inflation.

Left atrial spontaneous echo contrast assessed by TEE in patients with either native mitral valve disease or mitral valve replacement.

The incidence of spontaneous echo contrast in the left atrium, the factors with which it is associated, and its clinical significance were studied in 128 patients with native mitral valve disease or mitral valve replacement. All patients underwent both transesophageal and transthoracic echocardiography. Spontaneous echo contrast was visualized in 42 patients (33%) during transesophageal and in none during transthoracic echocardiography. Patients with spontaneous echo contrast had a significantly larger left atrial diameter (6.1 [1.1] cm vs 4.9 [0.9] cm, p < 0.001) and a greater incidence of both atrial fibrillation (54% vs 4%, p < 0.001) and left atrial thrombi (60% vs 28%, p < 0.01) compared with patients without spontaneous echo contrast. Multivariant analysis confirmed that these factors were independently associated with spontaneous echo contrast (left atrial size, p < 0.001; atrial fibrillation, p < 0.001; left atrial thrombus, p < 0.01). Patients with pure mitral regurgitation did not have any spontaneous echo contrast and anticoagulation did not influence its incidence. Spontaneous echo contrast was the only factor that was associated with a previous history of systemic embolization (history of systemic emboli in 28.6% of patients with spontaneous echo contrast vs 13.9% without spontaneous echo contrast, p < 0.05). In conclusion, spontaneous echo contrast is a common finding in the left atrium of patients with mitral valve disease or mitral valve replacement and represents a marker of increased thromboembolic risk in these patients.

Potential value of oral beta 2-adrenoceptor agonists in congestive heart failure: a haemodynamic and metabolic study.

This study was designed to investigate and compare the haemodynamic and metabolic responses to pirbuterol and salbutamol in patients with congestive heart failure and coronary artery disease. Attention was directed towards the effects these beta 2-adrenoceptor agonists have on left ventricular systolic function, systemic and coronary haemodynamics and myocardial substrate metabolism. Sixteen patients were randomly allocated to treatment with either pirbuterol 20 mg or salbutamol 6 mg. Since no statistically significant differences between the responses to these drugs were observed, combined data for both agents are presented. Ninety minutes after the drug intervention cardiac index increased from 2.2 +/- 0.1 to 2.9 +/- 0.2 1/min per m2 (P less than 0.001) in association with marked reductions in systemic vascular resistance (from 22 +/- 1 to 15 +/- 1 units, P less than 0.001) and increments in left ventricular dp/dtmax (from 1074 +/- 85 to 1422 +/- 133 mm Hg/sec, P less than 0.05). Modest reductions in left ventricular end-diastolic pressure (from 21 +/- 1 to 15 +/- 1 mm Hg, P less than 0.01) were observed. Heart rate increased from 82 +/- 5 to 91 +/- 4 beats/min (P less than 0.01) but the small fall in mean arterial pressure (from 86 +/- 3 to 78 +/- 3 mm Hg) was not significant. Drug-induced coronary vasodilatation reduced coronary coronary vascular resistance from 0.65 +/- 0.06 to 0.47 +/- 0.04 units (P less than 0.01) and led to a marked increase in coronary sinus blood flow (from 124 +/- 9 to 155 +/- 9 ml/min, P less than 0.05). Arterial levels of free fatty acids increased from 0.78 +/- 0.13 to 1.05 +/- 0.18 mmol/l (P less than 0.05) resulting in the preferential utilization of this substrate as a myocardial energy source. Despite the substantial haemodynamic improvement, however, no significant increase in myocardial oxygen uptake or lactate production was observed. Thus, in patients with coronary artery disease and congestive heart failure pirbuterol and salbutamol improve left ventricular function by a combination of afterload reduction and positive inotropism such that no appreciable deterioration in myocardial energetics occurs.

Sonovue improves endocardial border detection and variability in assessing wall motion score and ejection fraction during stress echocardiography.

BACKGROUND: Stress echocardiography is useful for assessing patients with coronary artery disease unable to undergo formal exercise testing. Considerable skill is required to avoid large intra- and inter-observer variability due to poor endocardial definition. Intravenous ultrasound contrast agents are now available which may improve this variability. AIM: To study intravenous Sonovue in assessing wall motion score and ejection fraction (EF) during stress echocardiography. METHODS: Thirty-eight patients undergoing arbutamine stress echocardiography for known or suspected coronary artery disease were studied. Echocardiographic analysis of wall motion score index, endocardial border detection (EBD) and EF was performed at rest and at peak stress before and after intravenous injection of Sonovue, by experienced and inexperienced observers. RESULTS: All three observers noted an improvement in endocardial border definition following Sonovue (p=<0.001). At baseline, there was a significant difference in wall motion score index between experienced and inexperienced observers at rest (p=0.01) and at peak stress (p=0.001). Following Sonovue administration this was no longer significant (p=0.07, p=0.114). Intra-observer variability of end diastolic, end systolic volumes (ESV) and EF improved following contrast (p<0.05) at rest and during stress. CONCLUSION: Sonovue significantly improved EBD and reduced intra-observer variability of EF at rest and during peak arbutamine infusion.

Echocardiography.

Imaging echocardiography is an important extension of the clinical examination and will answer most questions in an emergency-for example, whether an enlarged cardiac shadow on the chest radiograph represents ventricular dilatation or an effusion. Doppler ultrasonography is essential for hospitals with an interest in cardiology because it provides direct haemodynamic data that are complementary to imaging. It requires more skill than imaging and may also be time consuming. Colour flow Doppler mapping is speedy and simple to use and aids the interpretation of continuous wave Doppler. It is therefore a natural companion to conventional Doppler, but there would have to be a high clinical load to justify its purchase.

Balloon dilatation of the aortic valve for inoperable aortic stenosis.

The place of balloon dilatation of the aortic valve in the treatment of calcific aortic stenosis is controversial. Thirty two patients (mean age 76) in whom valve replacement was contraindicated were followed up for three to 24 months (mean 8); 25 were in functional class III or IV according to the New York Heart Association's classification. Major complications of the procedure occurred in four patients. Echocardiography and Doppler studies were performed before operation and before discharge in 28 patients, and the area of the valve was measured again six to 50 (mean 23) weeks after operation in 11 patients. The peak to peak aortic pressure gradient fell from a mean of 65 (SD 24) to 46 (20) mm Hg, but the area of the aortic valve, measured by Doppler echocardiography, in 18 patients showed a modest but significant increase, from 0.61 (0.16) to 0.74 (0.23) cm2. One month after dilatation, 29 patients were alive, of whom 17 had improved symptoms. Only two had lasting clinical benefit. Sixteen patients died, 12 of a cardiac cause. The estimated one year survival rate was 49%. Six patients underwent or required valve replacement because of persisting symptoms. In view of its limited long term efficacy balloon dilatation of the aortic valve should be used only for patients with severe symptoms whose life expectancy is limited by other disease or who are considered to be unsuitable for valve replacement. It may have a role in improving the condition of patients who present with cardiogenic shock or pulmonary oedema before valve replacement is undertaken.

Three-dimensional echocardiography.

Over the past two to three decades echocardiography has come a considerable distance from the early M-mode machines, and has become an indispensable diagnostic tool in any cardiovascular department. It has long been proved to be safe and cost-effective, and its clinical versatility has steadily increased with the continued integration of newer techniques, such as two-dimensional and harmonic imaging, Doppler and much more. One of the more recent developments in the field is three-dimensional echocardiography (3DE). 3DE, in various forms, has been used as a research tool for many years now, but lately improvements in software and transducer technology have begun to facilitate its integration into clinical practice. As with any technique, 3DE has its strengths and weaknesses, and these must be fully appreciated if it is to be utilised effectively.

Effects of cardiac resynchronisation therapy in patients with heart failure having a narrow QRS Complex enrolled in PROSPECT.

INTRODUCTION: Current guidelines recommend cardiac resynchronisation therapy (CRT) in patients with severe symptomatic heart failure, depressed left ventricular (LV) systolic function and a wide QRS complex (>or=120 ms). However, patients with heart failure having a narrow QRS complex might also benefit from CRT. DESIGN SETTING PATIENTS INTERVENTIONS: During the Predictors of Response to Cardiac Resynchronisation Therapy (PROSPECT) trial, 41 patients were enrolled in a 'narrow' QRS sub-study. These patients had a QRS complex <130 ms, but documented evidence of mechanical dyssynchrony by any of seven pre-defined echocardiographic measures. RESULTS: After 6 months of CRT, 26 (63.4%) patients showed improvement according to the Clinical Composite Score, 4 (9.8%) remained unchanged and 11 (26.8%) worsened. In patients with paired data, the 6-min walking distance increased from 334+/-118 m to 382+/-128 m, (p=0.003) and quality-of-life score improved from 44.2+/-19.7 to 26.8+/-20.2 (p<0.0001). Furthermore, there was a significant decrease in LV end-systolic diameter (from 59+/-9 to 55+/-12 mm, p=0.002) and in LV end-diastolic diameter (from 67+/-9 to 63+/-11 mm, p=0.007). CONCLUSION: The results suggest that CRT may have a beneficial effect in heart failure patients with a narrow QRS complex and mechanical dyssynchrony as assessed by echocardiography. The majority of patients improved on clinical symptoms, and there was an evident reduction in LV diameters. Larger studies are needed to clearly define selection criteria for CRT in patients with a narrow QRS complex.