Common arterial trunk in a cat: a high-resolution morphological analysis with micro-computed tomography

A 6-month-old female cat presented with respiratory distress. Physical examination showed a grade 5/6 holosystolic murmur with prominent precordial impulse over the left cranial chest wall. Echocardiography revealed bilateral hypertrophy of the ventricular walls, a dilated ascending aorta overriding the interventricular septum, a membranous ventricular septal defect and no obvious pulmonary trunk or pulmonary artery branches. Turbulent blood flow was detected around the ventricular septal defect and ascending aorta. Follow-up assessment, 12 months later, revealed marked and progressive biatrial dilation and biventricular hypertrophy. Four months after that, the cat died of severe congestive heart failure. To make a definitive postmortem diagnosis, we performed contrast enhanced micro-computed tomography (CT) on the ex vivo heart with micron-scale spatial resolution imaging and three-dimensional reconstruction. Micro-computed tomography analysis confirmed a common arterial trunk that bifurcated into the left pulmonary artery and aorta 5-mm distally from the truncal valve. The pulmonary trunk was absent. Slightly distal to the first branching, the common arterial trunk further branched into the right pulmonary artery and ascending aorta, indicating the aortic dominant form. Although CT angiography would be a preferred imaging modality for living animals, micro-computed tomography is a valuable tool for the ex vivo diagnosis of complex cardiac anomaly, such as presented in this cat.

Aging change of left ventricular function in children evaluated by acoustic quantification method

BACKGROUND

There are few reports about acoustic quantification (AQ) in the area of pediatrics. We aim to determine normal values of AQ analysis and investigate the aging change of left ventricular function in children.

METHODS

The subjects in this study included 137 patients (aged 29 days to 18 years) who had normal cardiac function and no cardiac load. None of the patients were receiving medical therapy. The instrument used was a PH-6500 (Philips, Andevor). Change of left ventricular area in short-axis view was detected by AQ analysis. From the mitral inflow, peak early (E) and peak late (A) diastolic velocities were measured, and E/A was calculated.

RESULTS

End-diastolic area (EDA) and end-systolic area (ESA) increased with age. Fractional area change (FAC) decreased with age. Peak ejection rate (PER) and peak rapid filling rate (PRFR) decreased with age up to 10 years. Atrial filling fraction (AFF) decreased and E/A increased with age up to 5 years.

CONCLUSIONS

Maturational or developmental alterations in LV diastolic properties were found up to 5 years old. AQ analysis is one of the useful indexes for investigating left ventricular diastolic function.

Characteristics of Doppler myocardial echocardiography in patients with tricuspid atresia after total cavopulmonary connection with preserved systolic ventricular function

BACKGROUND

Doppler myocardial echocardiography (DME) may be an excellent additional means of assessing determinants of systolic and diastolic ventricular function in patients with tricuspid atresia (TA) after total cavopulmonary connection (TCPC).

METHODS AND RESULTS

Thirty-three patients with TA and normal systolic shortening/ejection fraction (M-mode) after TCPC were studied by DME at a median age of 7.6 years (range 1.5-17 years). These results were compared to 16 age matched normal controls. Median time under a cavopulmonary shunt was 5.2 years (range 0.6-13.3 years). Isovolumic acceleration and isovolumic velocity did not differ significantly. All other systolic (S-wave acceleration-velocity and S-wave duration) and diastolic DME indices (E-deceleration-velocity, A-velocity and E/A ratio) were significantly lower in TCPC patients in comparison to normals (p<0.0001). Furthermore, isovolumic relaxation time (IRT) was significantly prolonged in the patient group (p<0.0001). Even though there was a significant correlation between the time of volume unloading and left ventricular end-diastolic diameter, exclusion of all patients with short period of volume unloading and relatively large systemic ventricles did not alter the results.

CONCLUSIONS

Patients with TA after TCPC and normal shortening and ejection fraction have normal isovolumic acceleration. Load dependent DME indices of systolic and diastolic function, however, were significantly reduced. These findings suggest that the described DME indices mirror the "normal" hemodynamics after TCPC in patients with TA. It needs to be assessed, whether this is an index of adverse prognosis in long-term surveillance of these patients.

Filling patterns in left ventricular hypertrophy: a combined acoustic quantification and Doppler study

OBJECTIVES

The purpose of this study was to evaluate the potential of acoustic quantification compared with Doppler echocardiography for assessment of left ventricular diastolic dysfunction.

BACKGROUND

Diastolic dysfunction usually accompanies left ventricular hypertrophy. Although Doppler echocardiography is widely used, it has known limitations in the diagnosis of diastolic abnormalities. The ventricular area-change waveform obtained with acoustic quantification technology may provide an alternative to assess diastolic dysfunction.

METHODS

Potential acoustic quantification variables (peak rate of area change and mean slope of area change rate during rapid filling, amount of relative area change during rapid filling and atrial contraction) were obtained and compared with widely used Doppler indexes of ventricular filling (isovolumetric relaxation time, pressure half-time, peak early diastolic velocity/peak late diastolic velocity ratio, rapid filling, atrial contribution to filling) in 16 healthy volunteers and 30 patients with left ventricular hypertrophy.

RESULTS

Criteria for abnormal relaxation were present in 68% of patients by acoustic quantification and in 64% of patients by Doppler echocardiography. However, abnormal relaxation was identified in 80% of patients by one or both methods. Acoustic quantification indicated abnormal relaxation in the presence of completely normalized Doppler patterns and in patients with mitral regurgitation or abnormal rhythm with unreliable Doppler patterns.

CONCLUSIONS

Acoustic quantification potentially presents a new way to assess diastolic dysfunction. This technique may be regarded as complementary to Doppler echocardiography. The combined use of the methods may improve the diagnosis of left ventricular relaxation abnormalities.

Comparison of acoustic quantification and Doppler echocardiography in assessment of left ventricular diastolic variables

OBJECTIVE

To assess the haemodynamic correlations of the waveforms of left ventricular area change obtained by automated boundary detection with newly developed acoustic quantification technology.

DESIGN

The timing of events in the cardiac cycle was identified on the wave-form automated boundary detection and was correlated with the corresponding timing derived from pulsed wave Doppler flow velocity traces of the mitral valve and left ventricular outflow tract. The amounts of area change during the rapid filling phase and during atrial contraction were correlated with the time-velocity integrals of early and late diastolic ventricular filling obtained from Doppler tracings of the mitral inflow.

SETTING

A university medical school echocardiography laboratory.

SUBJECTS

16 healthy volunteers and 19 patients referred for echocardiographic studies.

RESULTS

A significant correlation was found between the methods for measurement of the time from the R wave to mitral valve opening (r = 0.72, p < 0.01), isovolumic relaxation time (r = 0.62, p < 0.01), and ejection time (r = 0.54, p < 0.01). The change of total area that occurred during rapid filling and atrial filling phases measured from the acoustic waveform correlated with the time-velocity integrals of the early and late diastolic mitral valve inflow velocity derived from Doppler echocardiography (r = 0.60 and r = 0.80, respectively).

CONCLUSION

The waveform of left ventricular area obtained by the automated boundary detection technique identifies the phases of the cardiac cycle and correlates with Doppler values of left ventricular diastolic function. Therefore, this new method of automated boundary detection has potential uses in the assessment of left ventricular diastolic function.

Doppler echocardiographic patterns of left ventricular filling in patients early after acute myocardial infarction

Diastolic function is routinely assessed using Doppler-derived left ventricular (LV) filling patterns. Ratios between peak flow velocities during early filling and atrial contraction (E/A) of less than 1 are considered pathologic and diagnostic of impaired relaxation. Myocardial stiffness can normalize the E/A ratio, and thus, in some clinical settings, a normal E/A ratio may identify patients with high filling pressures. LV filling patterns were studied with Doppler echocardiography in 15 healthy subjects and 38 patients with recent acute myocardial infarction. The results were correlated with clinical and hemodynamic variables. E/A ratio less than 1 was found in 14 patients (37%) and in only 1 control subject; E/A ratio greater than 2 found in 5 patients (13%) and in only 1 control subject; 19 patients (50%) had an apparently normal E/A ratio. No correlation was found between LV filling pattern and ejection fraction or presence of diabetes or arterial hypertension. LV end-diastolic pressures were low to normal in patients with an E/A ratio less than 1 and were usually greater than 15 mm Hg in those with normal or abnormally increased (greater than 2) E/A ratios. Thus, an apparently normal E/A ratio in patients after myocardial infarction may identify those with more severe LV diastolic dysfunction and increased LV filling pressure.

Studies on blood rheology in patients with primary pulmonary hypertension

The rheologic properties of blood were studied in 6 patients with primary pulmonary hypertension (PPH) and compared with those of a control group of 10 healthy subjects. Blood viscosity was studied with a rotational viscometer and blood cell deformability with a filtrometer giving values for clogging particles (CP) and red cell transit time (RCTT). Blood viscosity at varying shear rates was found to be increased both at natural (p less than 0.025-0.005) and standardized hematocrit, 45% (p less than 0.05 at 40 s-1) in patients with PPH. Red cell deformability was reduced as indicated by a significant increase of RCTT (p less than 0.01). Increased values for hematocrit (p less than 0.001), hemoglobin concentration (p less than 0.001), and erythrocyte count (p less than 0.005) were found and decreased values for mean corpuscular hemoglobin concentration (MCHC) (p less than 0.025) and HDL cholesterol (p less than 0.005). Plasma viscosity, white cell deformability, white cell count, mean corpuscular volume (MCV), and plasma fibrinogen concentration did not significantly differ from the values found in the control group. It is concluded that patients with PPH have impaired blood rheology. The hemorheologic abnormalities in these patients may be of hemodynamic significance.

Doppler echocardiographic evaluation of congenital cardiac disease. An introduction

M-mode and two-dimensional echocardiography have greatly enhanced the evaluation of animals with congenital cardiac disease. Structural abnormalities can be seen and hemodynamic alterations inferred, e.g., ventricular wall concentric hypertrophy indicating pressure overload to the respective ventricle. Interrogation of the diseased heart by Doppler echocardiography allows acquisition of more direct hemodynamic information without cardiac catheterization, which enables the clinician to give a more precise description of a congenital abnormality. The purpose of this study is to illustrate and describe abnormal blood-flow patterns in selected congenital cardiac defects in animals. Basic background information concerning Doppler echocardiographic principles, flow patterns, and calculations will be briefly discussed. For more detailed descriptions other references should be sought. Interpretation of Doppler echocardiography in animals is based primarily on data derived from human studies since studies involving measurable numbers of veterinary patients have not yet been completed.

Transmitral velocities measured by pulsed Doppler in healthy volunteers: effects of acute changes in blood pressure and heart rate

The effect of a two minute cold pressor test on transmitral velocities measured by pulsed Doppler was studied in 11 healthy volunteers. Blood pressure increased significantly during cold immersion but peak atrial and peak early diastolic transmitral velocities and their ratio (A:E) were unchanged. There was no correlation between changes in Doppler variables and changes in calculated mean arterial blood pressure during the test. Heart rate changes were variable and not related to changes in blood pressure. In individual people the change in pulse interval during cold immersion was significantly and inversely correlated with the change in the A:E ratio. The large acute increase in arterial pressure seen during the cold pressor test in normal volunteers had no consistent effect on the transmitral velocity profile although small changes in heart rate were associated with large changes in A:E ratio. The effect of small changes in heart rate may be of considerable importance in determining transmitral velocity profiles. Thus in clinical and experimental studies in which the heart rate is not controlled, Doppler data on transmitral flow should be interpreted with caution.