Novel imaging strategies for the detection of prosthetic heart valve obstruction and endocarditis.

Prosthetic heart valve (PHV) dysfunction remains difficult to recognise correctly by two-dimensional (2D) transthoracic and transoesophageal echocardiography (TTE/TEE). ECG-triggered multidetector-row computed tomography (MDCT), 18-fluorine-fluorodesoxyglucose positron emission tomography including low-dose CT (FDG-PET) and three-dimensional transoesophageal echocardiography (3D-TEE) may have additional value. This paper reviews the role of these novel imaging tools in the field of PHV obstruction and endocarditis.For acquired PHV obstruction, MDCT is of additional value in mechanical PHVs to differentiate pannus from thrombus as well as to dynamically study leaflet motion and opening/closing angles. For biological PHV obstruction, additional imaging is not beneficial as it does not change patient management. When performed on top of 2D-TTE/TEE, MDCT has additional value for the detection of both vegetations and pseudoaneurysms/abscesses in PHV endocarditis. FDG-PET has no complementary value for the detection of vegetations; however, it appears more sensitive in the early detection of pseudoaneurysms/abscesses. Furthermore, FDG-PET enables the detection of metastatic and primary extra-cardiac infections. Evidence for the additional value of 3D-TEE is scarce.As clinical implications are major, clinicians should have a low threshold to perform additional MDCT in acquired mechanical PHV obstruction. For suspected PHV endocarditis, both FDG-PET and MDCT have complementary value.

Diagnostic accuracy of transesophageal echocardiography during cardiopulmonary resuscitation.

OBJECTIVES: We sought to establish the diagnostic accuracy of transesophageal echocardiography (TEE) during cardiopulmonary resuscitation. BACKGROUND: Because of its bedside diagnostic capabilities, excellent cardiac images and lack of interference with resuscitation efforts, TEE is ideally suited to determine the cause of a circulatory arrest that is not due to severe arrhythmia. However, the diagnostic accuracy of TEE during resuscitation is unknown. METHODS: TEE was performed in patients with prolonged circulatory arrest. The TEE diagnoses were compared with diagnoses from autopsy, surgery and clinical follow-up. RESULTS: Of the 48 study patients (29 male, 19 female, mean age +/- SD 61 +/- 20 years), 28 had an in-hospital cardiac arrest and 20 an out-of-hospital onset of arrest. Forty-four patients eventually died; four survived to discharge. The diagnoses made with TEE were cardiac tamponade (n = 6), myocardial infarction (n = 21), pulmonary embolism (n = 6), ruptured aorta (n = 1), aortic dissection (n = 4), papillary muscle rupture (n = 1), other diagnosis (n = 2) and absence of structural cardiac abnormalities (n = 7). A definite diagnosis from a reference standard was available in 31 patients. The TEE diagnosis was confirmed in 27 of the 31-by postmortem examination (n = 19), operation (n = 2), angiography (n = 2) or clinical course (n = 4). In the other four patients the TEE diagnosis proved incorrect by postmortem examination. The sensitivity, specificity and positive predictive value of TEE were 93%, 50% and 87%, respectively. In 15 patients (31%), major therapeutic decisions were based on TEE findings. CONCLUSIONS: TEE can reliably establish the cause of a circulatory arrest during cardiopulmonary resuscitation.

Pathogenesis of mitral regurgitation in acute myocardial infarction: importance of changes in left ventricular shape and regional function.

The pathogenesis of mitral regurgitation (MR) was determined by quantitative echocardiography in 188 patients with acute myocardial infarction (AMI) within 48 hours after admission. MR was classified, by using color Doppler, as significant (grades 3 to 4) or trivial (grades 0 to 2). Left ventricular (LV) function (global and regional), volume, and shape, as well as mitral valvular features, were measured and analyzed by stepwise logistic regression. Significant MR occurred in 25 (13%) patients. Univariately, recurrent infarction (p < 0.01), LV dilation (p < 0.001) and sphericity (p < 0.001), inferoposterolateral asynergy (p < 0.001), mitral annular dilatation (p < 0.005), and mitral leaflet restriction (p < 0.05) were associated with significant MR. In regression analysis, only recurrent infarction (odds ratio 5.08), LV sphericity index (odds ratio 1.12), and inferoposterolateral asynergy (odds ratio 6.07) were independently associated with significant MR, whereas none of the mitral valvular features examined had an independent association. In conclusion, changes in LV shape and regional function and not mitral valvular changes are prime determinants of significant MR after AMI.

The orientation of the bi-leaflet CarboMedics valve in the mitral position determines left ventricular spatial flow patterns.

OBJECTIVES: In the mitral annulus bi-leaflet mechanical valves can be oriented in two ways: the anatomical orientation with the hinge line parallel to a line through the commissures of the native valve (90 degrees). The influence of this orientation on the left ventricular spatial flow pattern and valve leaflet opening was investigated in pigs. METHODS: In 9 pigs a CarboMedics mitral valve prosthesis was implanted in the ) degree position and in 9 pigs in the 90 degree orientation. Two dimensional echocardiographic and color Doppler recordings were performed before surgery, immediately after surgery and after 6 weeks. RESULTS: In the native valve the diastolic flow pattern was characterized by a central inflow and backflow away from the apex along the left ventricular wall. In the 0 degree orientation a diastolic flow pattern with an asymmetrical inflow was observed, resulting from a greater extension of the jet along the lateral wall compared to the jet along the interventricular septum. Mid-diastolic back-flow away from the left ventricular apex was directed towards the valve prosthesis. In the 2-dimensional echocardiographic recordings the opening angle of both prosthetic leaflets was different showing a larger opening angle of the posterior leaflet. In the 90 degree orientation a diastolic flow pattern with paradoxical flow directions was recorded, that could only be explained in a 3-dimensional way: one inflow jet along the anterior wall, one inflow jet along the posterior wall and back-flow away from the apex sandwiched in between the two inflow jets. In this orientation the 2-dimensional echocardiographic recordings showed symmetrical opening of the two leaflets of the prosthesis. CONCLUSIONS: The orientation of the CarboMedics bi-leaflet mechanical valve prosthesis in the mitral valve annulus determines the left ventricular spatial flow pattern. The flow pattern resulting from the 0 degree orientation, was associated with asymmetrical leaflet motion, while the 90 degree orientation flow pattern was associated with symmetrical leaflet motion. These findings may be of importance for prosthetic valve function as well as for left ventricular kinetics.

Office, nurse, basal and ambulatory blood pressure as predictors of hypertensive target organ damage in male and female patients.

The objective of this study was to assess the value of two substitutes for ambulatory blood pressure (BP) monitoring: nurse-measured BP and BP measured by an automated device during 1 h resting in the clinic (basal BP). Hypertensive patients in an academic out-patients clinic were selected consecutively. We compared the relation of indices of early target organ damage (echocardiographically determined left ventricular mass index (LVMI) and urinary albumin excretion (expressed as albumin/creatinine ratio: ACR) to physician measured and nurse measured basal and ambulatory BP. The relation of BP to LVMI and the logACR were also studied for both sexes separately. Sixty-two patients (28 men, 34 women) were included, all untreated for >3 months. Systolic office BP was not significantly related to the LVMI (r2 = 0.04, P > 0.05), whereas nurse measured (r2 = 0.11, P < 0.05), basal (r2 = 0.13, P < 0.01) and ambulatory daytime (r2 = 0.13, P < 0.05) and night time (r2 = 0.17, p < 0.001) SBP did have a significant relation to LVMI. There was no difference in the relation of office, nurse, basal or ambulatory BP to logACR. In contrast to the highly significant relation of SBP to LVMI for male patients (day: r2 = 0.29, P < 0.01, night: r2 = 0.46, P < 0.001) this relation was non-existent for female patients (day: r2 = 0.09, P > 0.05, night: r2 = 0.02, P > 0.05). The relation between BP and logACR did not differ between the sexes. We conclude that: (1) to some degree nurse measured and basal BP may be considered as better predictors of early hypertensive target organ damage than physician measured BP; and (2) there is a pronounced sex difference in the relation of BP to left ventricular mass.

Usefulness of combined two-dimensional echocardiography and transesophageal atrial stimulation early after acute myocardial infarction.

Transesophageal atrial stimulation (TRAS) was combined with 2-dimensional echocardiography in 69 consecutive patients on days 3 to 5 (mean 3.3) of their first, uncomplicated myocardial infarction, to determine if inducible remote asynergy (i.e., not directly adjacent to the infarcted area and supposedly related to another vascular territory) provides information regarding (1) extent of coronary artery disease, and (2) future ischemic events. Uncomplicated, adequate stress studies were performed in 59 of 69 patients (86%); all these patients had regional asynergy at rest. Remote asynergy at rest was present in 7 patients and during TRAS in 26 patients. Coronary angiography was performed within 2 to 3 weeks after the acute phase. Multivessel disease was present in 23 of these patients and absent in 3. Of the 33 patients without remote asynergy during TRAS, 5 had multivessel disease. Sensitivity of remote asynergy during TRAS for detecting multivessel CAD was 82%, specificity 90%, and predictive accuracy 86%. New ischemic events, defined as recurrent infarction, cardiac death, or revascularization within 12 to 18 months (mean 12.6) occurred in 24 patients (41%); remote asynergy during TRAS was present in 16 of these patients (67%). It is concluded that TRAS combined with 2-dimensional echocardiography can safely be performed in the early days of acute myocardial infarction; remote asynergy during TRAS reliably identifies patients with multivessel disease and future ischemic events.

Usefulness of mitral regurgitation in protecting against left ventricular thrombus after acute myocardial infarction.

In conclusion, we documented an increased incidence of LV thrombus in patients with MR after AMI.

Doppler left ventricular flow pattern versus conventional predictors of left ventricular thrombus after acute myocardial infarction.

OBJECTIVES: The value of Doppler-derived left ventricular spatial flow patterns in predicting left ventricular thrombus formation after myocardial infarction was compared with that of conventional clinical and echocardiographic variables. BACKGROUND: Assessment of left ventricular thrombosis risk after myocardial infarction is important because of potential embolic sequelae that are reduced by oral anticoagulant agents. METHODS: Clinical, two-dimensional and Doppler echocardiographic data were prospectively obtained in 104 patients with acute myocardial infarction within 48 h of admission. Ventricular flow was assessed by Doppler echocardiography and considered normal when brisk ventricular inflow with simultaneous onset at the mitral valve and apical levels was present, together with alternating directions of apical flow throughout the cardiac cycle. In addition to normal flow, two abnormal flow patterns were recognized: apical rotating flow and vortex ring formation. Oral anticoagulant agents were prescribed only to patients with abnormal flow at admission. The incidence of left ventricular thrombosis was assessed by echocardiography during 9 months of follow-up. RESULTS: Abnormal flow pattern had a positive predictive value of 63% and a negative predictive value of 99%. On stepwise logistic regression analysis, only abnormal flow pattern had an independent relation to left ventricular thrombus (odds ratio 92). CONCLUSIONS: Left ventricular flow pattern derived by Doppler echocardiography soon after admission is superior to conventional clinical and two-dimensional echocardiographic assessment in estimating the risk of left ventricular thrombosis after myocardial infarction.

Recombinant endotoxin-binding protein (rBPI23) attenuates endotoxin-induced circulatory changes in humans.

In the present study the protective effect of a recombinant endotoxin-binding protein rBPI23 on the circulatory changes in experimental endotoxemia in humans was investigated. In a controlled, blinded crossover study, eight volunteers were challenged twice with an intravenous bolus injection of endotoxin (40 EU/kg body weight), and concurrently received either rBPI23 (1 mg/kg) or placebo (human serum albumin, 0.2 mg/kg). Hemodynamic parameters were obtained non-invasively by means of M-mode, two-dimensional, and Doppler echocardiography. rBPI23 significantly reduced indices of the endotoxin-induced hyperdynamic circulation. rBPI23 treatment significantly reduced increase in cardiac index (P = 0.0156). rBPI23 treatment diminished the endotoxin-induced decrease in systemic vascular resistance index (P = 0.0304). rBPI23 did not prevent the endotoxin-induced rise in body temperature and systolic, diastolic and mean arterial pressure were not significantly different in the rBPI23- and placebo-treatment arm. Both treatment periods showed a small reduction in end diastolic and end systolic volumes. rBPI23 treatment slightly reduced the increase in M-mode ejection fraction and fractional shortening. These results indicate that rBPI23 is capable of attenuating the potentially deleterious circulatory effects of endotoxin in humans.

Doppler echocardiographic evaluation of left ventricular diastolic function after surgical correction of atrial septal defect during childhood.

Transmitral flow was studied using Doppler echocardiography with the A/E ratio as a parameter of left ventricular diastolic function in 21 patients (ages 2.5-30.0 years) who had undergone early surgical correction of an isolated secundum type atrial septal defect (ASD) compared to a healthy cohort of 21 subjects. Pre- and postoperative M-mode recordings were compared in 12 of the 21 patients to evaluate the effect of operation on interventricular septal motion (IVS) and left ventricular (LV) and right ventricular (RV) end-diastolic diameter ratio (LVDD/RVDD) as parameters of right ventricular volume overload. No significant difference in A/E ratio was found between the patient and control groups. IVS was shown to normalize in 11 of 12 patients postoperatively and to improve from paradox to flattened in 1 of 12. LVDD/RVDD increased from 1.26 +/- 0.31 to 2.10 +/- 0.51 (p = 0.0008), with no significant difference remaining between the control and patient groups postoperatively. These findings support the conclusion that an intrinsic abnormality of the left ventricle is not responsible for its diastolic dysfunction in patients with ASD who develop left ventricular failure, thereby implicating an acquired abnormality. Mechanical sequelae of right ventricular volume overload were shown to normalize in all patients subsequent to operation in the present study, and therefore cannot be excluded as a cause of left ventricular failure in ASD.

Mitral valve anatomy and morphology: relevance to mitral valve replacement and valve reconstruction.

An endoscope was used to study the anatomy and morphology of the native mitral valve inside an isolated pig heart working under physiological conditions. Annulus motion, valve leaflet function, and the anatomy of the chords and branching pattern are described. Anatomical and functional details relevant to mitral valve reconstruction and valve replacement are outlined. Because of the similarity with the human heart, we have assumed that the observations made in the pig heart also apply to humans.

Left atrial appendage blood flow determined by transesophageal echocardiography in healthy subjects.

Transesophageal echocardiography was performed in 46 healthy subjects to define characteristics of normal left atrial appendage blood flow. Three different flow wave patterns were observed that were heart rate dependent (p < 0.01). A quadriphasic pattern, consisting of 2 diastolic forward (emptying) flow waves each followed by a backward (filling) flow wave, was present in 36 subjects (78%). Triphasic appendage flow was observed in 6 subjects (13%) and biphasic flow in 4 (9%). Mean heart rates among subjects with quadri-, tri- and biphasic flows were 75 +/- 11, 95 +/- 6 and 112 +/- 7 beats/min, respectively. Analysis of pulsed Doppler recordings of subjects with quadriphasic or triphasic appendage flow patterns showed that the onset of transmitral early diastolic peak flow wave was followed at 17 +/- 15 ms by the onset of pulmonary venous diastolic flow and at 43 +/- 17 ms by the onset of the first diastolic forward flow in the appendage. This sequence was constant and independent of heart rate (p < 0.01), suggesting a causal relation between left ventricular relaxation and the first diastolic forward flow wave in the appendage. The second diastolic forward flow followed the P wave on the electrocardiogram at 79 +/- 23 ms. Thus, left atrial appendage blood flow pattern in normal subjects is heart rate dependent, and ventricular relaxation appears to initiate early diastolic emptying of the appendage.

Free vortex ring formation in the left atrium originating in the left auricle.

An 80-year-old woman was evaluated by transesophageal echocardiography after coronary artery bypass surgery and subsequent cardioembolic stroke. In addition to spontaneous echo contrast demonstrating a counterclockwise rotating blood flow pattern, we observed free vortex ring formation in the left atrium, originating in the left auricle. To our knowledge, this is the first reported case of abnormal free vortex ring type flow pattern in the left atrium.

Prediction of apical thrombus formation in acute myocardial infarction based on left ventricular spatial flow pattern.

The predictive value of the left ventricular spatial flow pattern for thrombus formation was determined in 62 patients with acute myocardial infarction. A normal flow pattern by pulsed Doppler echocardiography was characterized by 1) simultaneous onset of blood motion at the mitral valve and apical level, and 2) a discontinuous Doppler signal along the lateral wall and interventricular septum. The flow pattern was assessed by these criteria, within 24 h after the onset of complaints and after 6 and 12 weeks. In 46 of the 62 patients, a normal flow pattern was found at the first examination; none of these 46 patients developed a thrombus during the study period. An abnormal flow pattern was seen at the first examination in 16 patients; this pattern normalized during follow-up in 6 patients, none of whom developed a thrombus. In the other 10 patients the abnormal flow pattern persisted, and 7 of these developed a thrombus. These findings suggest that a normal left ventricular flow pattern in the setting of acute myocardial infarction is not associated with subsequent thrombus formation. This observation may be of importance if anticoagulation is considered.

Determinants of the occurrence of vortex rings in the left ventricle during diastole.

This study employs classical inviscid fluid dynamics theory to investigate whether LV diastolic inflow volume and the size of the LV play a role in vortex ring formation. Fluid injection across an orifice into a large container results in the generation of a vortex ring having a constant size and speed. Relations between the vortex size and speed and the injection were obtained by applying conservation laws regarding kinetic energy, impulse and vorticity; the initial state was computed using a bolus injection model, and the final state by using the Kelvin vortex model. An important parameter in the equations is the relative injection length, i.e., the ratio of the length of the injected bolus and the radius of the orifice (L/R). Its estimated highest value in man, L/R = 15, produces a rather thick vortex ring (relative thickness 0.77). Comparable results following from the Hill vortex model convinced us that the Kelvin vortex model can be applied in the whole range of injection lengths in the human left ventricle. In an in vitro model it is shown experimentally that vortex rings can be generated for L/R in the range from 2 to 16. The measured traveling speed of the vortex ring is in fair agreement with the theory, as well as the ring radius for large injections. A vortex ring located in a narrow channel cannot reach its proper traveling speed. The method of images is used to estimate the speed reduction of vortex rings within a cylinder. It turns out that propagation of vortex rings is possible when the ratio of orifice to cylinder radius is less than about 0.5.(ABSTRACT TRUNCATED AT 250 WORDS)