Left Ventricular Transverse Diameter Research Articles

Comparison of cardiovascular metrics on computed tomography pulmonary angiography of the updated and old diagnostic criteria for pulmonary hypertension in patients with chronic thromboembolic pulmonary hypertension.

In the 2022 European Society of Cardiology (ESC) and the European Respiratory Society (ERS) guidelines, the diagnostic criteria for pulmonary hypertension (PH) included a reduced mean pulmonary artery pressure (mPAP) of 20 mmHg (mPAP >20 mmHg). This study aimed to reassess cardiovascular metrics on computed tomography pulmonary angiography (CTPA) for chronic thromboembolic pulmonary hypertension (CTEPH) to optimize the timely diagnosis of patients with suspected PH. Patients with suspected CTEPH who underwent CTPA and right heart catheterization (RHC) between January 2019 and December 2022 in China-Japan Friendship Hospital were retrospectively included. They were grouped into CTEPH and non-PH groups according to the new and old criteria (2022 and 2015 ESC/ERS guidelines) for the diagnosis of PH. Cardiovascular metrics including the main pulmonary artery diameter (MPAd), Cobb angle, and right ventricular free wall thickness (RVWT), among others, were measured. The correlation of these metrics with hemodynamic data was analyzed with Spearman rank correlation analysis, while the differences in cardiovascular metrics between the updated (mPAP >20 mmHg) and old PH criteria (mPAP ≥25 mmHg) were compared with independent samples t-test or the Mann-Whitney test. Receiver operator characteristic (ROC) curve analysis was performed for the prediction model. The study enrolled 180 patients (males n=86; age 55.5±12.0 years old). According to the old guidelines, 119 patients were placed into the PH group (mPAP ≥25 mmHg) , while according to the new guidelines, 130 patients were placed into the PH group (mPAP >20 mmHg). Cardiovascular metrics on CTPA between the updated and old guidelines were comparable (P>0.05). Compared to other metrics, an MPAd of 30.4 mm exhibited the highest area under the curve (AUC: 0.934±0.021), with a sensitivity of 0.88 and specificity of 0.90. MPAd [odds ratio (OR) =1.271], transverse diameter of the right ventricle (RVtd; OR =1.176), Cobb angle (OR =1.108), and RVWT (OR =3.655) were independent factors for diagnosing CTEPH (P<0.05). Cobb angle, right and left ventricular transverse diameter ratio, and right and left ventricular area ratio moderately correlated with mPAP (r=0.586, r=0.583, r=0.629) and pulmonary vascular resistance (PVR) (r=0.613, r=0.593, r=0.642). Cardiovascular metrics on CTPA were comparable between the new and old guidelines for CTEPH diagnosis. Cardiovascular metrics on CTPA can noninvasively assess the hemodynamics of patients with CTEPH.

Clinical features and CT findings of fibrosing mediastinitis associated pulmonary hypertension

Objective: To investigate the clinical features and CT findings of pulmonary hypertension (PH) in patients with fibrosing mediastinitis (FM). Methods: Thirteen patients with FM diagnosed between September 2015 and June 2022 were studied retrospectively, including patients with PH (FM-PH group) and patients without PH (FM group) confirmed on right heart catheterization. The t test of two independent samples, Mann-Whitney U rank sum and Fisher's test were used to compare the general information, symptoms, laboratory examination, right ventricular and pulmonary artery measurement data and pulmonary artery CT findings between the two groups, respectively. Results: Compared with the 7 FM patients aged 28-79 (60.00±17.69) years, the 6 patients in the FM-PH group, aged from 60 to 82 (68.83±8.35) years, had more peripheral edema, lower percentage of PaO2, wider inner diameters of pulmonary artery and right ventricle, a higher ratio of right ventricle and left ventricular transverse diameter, faster tricuspid regurgitation velocity and higher estimated systolic pulmonary artery pressure (P<0.05). There were no differences in BNP levels and tricuspid annular plane systolic excursion between groups (P>0.05). Of the 6 patients with PH, 5 had precapillary PH and 1 had mixed PH. Except that the pulmonary vascular resistance in patients of the FM-PH group was significantly higher than that in the FM group (P<0.05), there were no significant differences in cardiac output, mixed venous oxygen saturation and pulmonary capillary wedge pressure between the two groups. CT pulmonary angiography (CTPA) showed pulmonary artery and vein stenosis. Patients in the FM-PH group had more severe stenosis and occlusion of pulmonary artery and pulmonary vein (P<0.05), and more involvement of multiple pulmonary veins (P<0.05). Conclusions: The clinical manifestation of FM complicated with PH is related to the degree of involvement of pulmonary artery, vein and airway. It is recommended that the disease be evaluated in combination with multiple parameters such as clinical manifestations, cardiac ultrasound, right cardiac catheter and CTPA.

Efficacy of transcatheter pulmonary valve perforation in neonates with pulmonary atresia with intact ventricular septum

Objective: To explore the efficacy and safety of transcatheter pulmonary valve perforation in the treatment of neonatal pulmonary atresia with intact ventricular septum (PA-IVS). Methods: The clinical data on surgical treatment and follow-up in 16 patients with PA-IVS who underwent transcatheter pulmonary valve perforation in Women and Children's Hospital, Qingdao University from October 2018 to October 2021 were analyzed retrospectively. The right ventricular systolic pressure and percutaneous oxygen saturation (SpO2) were compared before and after operation. In addition, the SpO2 and echocardiographic data at preoperative and the last follow-up were compared. Comparisons between groups were performed using paired-samples t test. Results: Among the 16 patients (10 males and 6 females) with the age at operation of 19 (14, 26) days, 12 cases underwent transcatheter pulmonary valve perforation successfully, 2 cases were transferred to surgery department for open-heart pulmonary valvulotomy, and the remaining 2 cases were transmitted to surgery department for transthoracic pulmonary valve perforation. The age at operation of the 12 patients who underwent transcatheter pulmonary valve perforation was 18 (14, 27) days, and the weight was (3.6±0.4) kg. The immediate postoperative right ventricular systolic pressure decreased significantly ((57±16) vs. (95±19) mmHg (1 mmHg=0.133 kPa), t=7.49, P<0.001), and the postoperative SpO2 was improved effectively (0.90±0.48 vs.0.75±0.09, t=-5.61, P<0.001). The follow-up time was 22 (7, 33) months for 12 patients who underwent transcatheter pulmonary valve perforation successfully. At the last follow-up, the ratio of right to left ventricular transverse diameter was significantly higher than that before operative (0.55±0.05 vs. 0.45±0.05, t=-3.27,P=0.007). Furthermore, the Z-scores of pulmonary valvular diameter (-0.78±0.23 vs. -1.73±0.56, t=-8.52, P<0.001) and the tricuspid valvular diameter (-0.52±0.12 vs. -1.46±0.38, t=-10.40, P<0.001) were all significantly higher than preoperative data. At last, all the patients achieved biventricular circulation without death or major complications. Conclusion: Transcatheter pulmonary valve perforation is a safe and effective therapy for neonatal PA-IVS, and its curative effect has been confirmed by the medium follow-up data.

Fetal cardiac evaluation in HIV-positive women under HAART therapy in a Romanian hospital.

Human immunodeficiency virus (HIV) is an RNA (ribonucleic acid) virus that causes acquired immunodeficiency syndrome (AIDS). This disease has a major socioeconomical impact. The aim of the present study was to assess the fetal heart structure and function in HIV-positive pregnant women on highly active antiretroviral therapy (HAART). This is a prospective study conducted between January, 2018 and December, 2019. The hearts of fetuses from 14 HIV-positive pregnant women on HAART were assessed. Statistically significant sex-related cardiac changes in HIV-exposed uninfected fetuses of pregnant women on HAART were found. A narrow aorta was detected in female fetuses and a smaller left ventricular transverse diameter in male fetuses. Overall, the myocardial performance index remained unaltered. The impact of antiretroviral therapy on fetal heart seems to be sex-related. Accurate and complete information about the risks and benefits of antiretroviral treatment and management strategies to improve fetal outcomes may also ensure better compliance of the mothers to this treatment.

Evaluation of Real-Time Three-Dimensional Echocardiography in Right Ventricular Function and Hemodynamics in Patients with Idiopathic Pulmonary Hypertension

Objective: Oriented with the assessment on real-time echocardiography based upon three dimensions (RT-3DE) in estimating right ventricular function and hemodynamics in the patients undergoing idiopathic pulmonary hypertension. Methods: Sixty patients living with idiopathic pulmonary hypertension admitted to our hospital from September 2018 to June 2019 were enrolled. Another 20 healthy examiners were selected as healthy controls. According to pulmonary systolic blood pressure, 60 patients were divided into 20 mild patients, 20 moderate ones as well as 20 severe ones. RT-3DE was used to measure right heart structure related parameters in all subjects, including left ventricular transverse diameter (LVTD), right ventricular transverse diameter (RVTD), right ventricular global end diastolic volume (EDV), right ventricular ejection fraction (RVEF). End-systolic volume (ESV), stroke volume (SV), as well as hemodynamic parameters, including pulmonary systolic pressure (SPAP), right heart output (RCO), pulmonary diastolic blood pressure (DPAP), pulmonary arterial pressure (MPAP). The differences in right heart structure parameters and hemodynamic parameters betwixt the PH Group and the healthy control Group were compared. In addition, conventional two-dimensional echocardiography (2DE) and RT-3DE were used to compare the images of the patients who had serious pulmonary hypertension and those of the Control Group to analyze the tricuspid annulus systolic displacement (TAPSE), the Tei index, and the tricuspid annulus systolic peak velocity (S’) value. The Result is that SPAP, DPAP, and MPAP achieved higher level in the PH Group compared to those in the Healthy Group, and P &lt; 0005, the difference took on statistical significance. Those data of SPAP, DPAP and MPAP in the moderate and severe PH Group were higher than those in the mild PH Group, and P &lt; 0005, the difference was of statistical significance. The RCO of the patients from the PH Group as well as the Healthy Group got under comparison, and P &lt; 0005. They presented statistics-based dramatic difference. In addition, RCO showed a gradual decline in the patients who came down with mild, moderate, and serious PH, and the results were statistically significant. In addition, the comparison between RT-3DE and conventional echocardiography shows that RT-3DE has higher accuracy and diagnostic value.

Efficacy of transcatheter pulmonary valve perforation by micro-guidewire and balloon dilation in neonates with pulmonary atresia with intact ventricular septum

Objective: To investigate the safety and efficacy of transcatheter perforation of pulmonary valve by micro-guidewire and balloon dilation in the treatment of neonatal pulmonary atresia with intact ventricular septum (PA-IVS). Methods: The retrospective study included 21 neonates (14 males and 7 females) with PA-IVS who underwent transcatheter micro-guidewire pulmonary valve perforation and balloon dilation in Xinhua Hospital from January 2012 to December 2018. All patients underwent the pulmonary valve perforation by micro-guidewire through the Simmons catheter. During the follow-up period at 1, 3, 6, 12 months postoperatively and annually thereafter, the operative efficacy and the development of the right ventricle (RV) were evaluated by echocardiography. Statistical analyses were performed using t test. Results: A total of 21 neonates with PA-IVS were enrolled, and 13 cases were diagnosed prenatally. The median age of surgery was 6 days, the weight was (3.2±0.5) kg. The balloon/valve ratio was 1.19±0.12, and the RV pressure measured by catheter was (121±33) mmHg (1 mmHg=0.133 kPa) . The immediate postoperative RV pressure was (47±13) mmHg. The median follow-up time was 30 months. All the cases enrolled achieved biventricular circulation without death and serious complications. According to the last follow-up data including 16 cases who were followed up for 1 year or longer, the pulmonary artery transvalvular pressure was (29±15) mmHg. The postoperation ratio of right to left ventricular transverse diameter was significantly higher than that before operation (0.86+0.10 vs. 0.73+0.13, t=-2.96, P=0.006). Compared with preoperative data, the postoperation pulmonary valvular diameter Z-score was significantly higher (-1.41±0.89 vs. -2.83±1.06, t=-3.65, P=0.001) and the tricuspid valvular diameter Z-score was significantly higher (-0.52±0.29 vs. -1.34±0.81, t=-3.55, P=0.001). Conclusion: Transcatheter perforation of pulmonary valve by micro-guidewire and balloon dilation is a safe and effective initial therapy for neonatal PA-IVS.

Correlation between pulmonary arterial presure and right ventricular function by echocardiography in chronic thromboembolic pulmonary hypertension

Objective To discuss the correlation between right ventricular function and systolic pulmonary artery pressure (PASP) in patients with chronic thromboembolic pulmonary hypertension (CTEPH) and explore the change of right ventricular function under different degree of PASP. Methods One hundred and thirty-seven CTEPH patients were divided into four groups by PASP: Group Ⅰ (50 mmHg≤PASP<70 mmHg), 20 cases; Group Ⅱ (70 mmHg≤PASP<90 mmHg), 35 cases; Group Ⅲ, 55 cases (90 mmHg≤PASP<110 mmHg); Group Ⅳ (PASP≥110 mmHg), 27 cases. Echocardiographic parameters include: PASP, tricuspid regurgitation area (ATR), left ventricular transverse diameter (LVTD), right ventricular transverse diameter (RVTD), inner diameter of main pulmonary artery (DMPA), inner diameter of left arterial branch (DLPA), inner diameter of right pulmonary arterial branch (DRPA). Right ventricular function parameters include: tissue Doppler-derived tricuspid lateral annular systolic velocity (s'), tricuspid annular plane systolic excursion (TAPSE), RV index of myocardial performance (RIMP) and right ventricular fractional area change (FAC). Results There were significant differences in RVTD, TAPSE, FAC and RIMP in CTEPH patients under different PASP(P<0.05). RV structure and function was significantly correlated with PASP in CTEPH patients. With the elevation of PASP, RV was significantly enlarged and RV function becomes worse. Conclusions Echocardiography may contribute to evaluate RV function in CTEPH patients and provide basis for clinical treatment and prognosis evaluation. Key words: Echocardiography; Pulmonary embolism; Hypertension, pulmonary; Ventricular function, right

Echocardiographic parameters in patients with pulmonary arterial hypertension: correlations with right ventricular ejection fraction derived from cardiac magnetic resonance and hemodynamics.

BackgroundEchocardiography is the most convenient method used to evaluate right ventricular function, and several echocardiographic parameters were studied in previous studies. But the value of these parameters to assess the right ventricular function in patients with pulmonary arterial hypertension (PAH) has not been well defined.MethodsPatients with PAH were observed prospectively. Right heart catheterization, echocardiography and cardiac magnetic resonance (CMR) were performed within 1 week interval. The correlations between echocardiographic parameters and right ventricular ejection fraction (RVEF) derived from CMR as well as hemodynamics were analyzed.ResultsThirty patients were enrolled including 24 with idiopathic PAH, 5 with PAH associated with connective tissue diseases and 1 with hereditary PAH. All echocardiographic parameters except right ventricular myocardial performance index (RVMPI) correlated significantly with RVEF (tricuspid annual plane systolic excursion [TAPSE], r = 0.440, P = 0.015; tricuspid annular systolic excursion velocity [S’], r = 0.444, P = 0.016; isovolumic acceleration [IVA], r = 0.600, P = 0.001; right ventricular fraction area change [RVFAC], r = 0.416, P = 0.022; ratio of right ventricular transverse diameter to left ventricular transverse diameter [RVETD/LVETD], r = −0.649, P<0.001; RVMPI, r = −0.027, P = 0.888). After adjusted for mean right atrial pressure, mean pulmonary arterial pressure and pulmonary vascular resistance (PVR), only IVA and RVETD/LVETD could independently predict RVEF. Four echocardiographic parameters displayed significant correlations with PVR (TAPSE, r = −0.615, P<0.001; S’, r = −0.557, P = 0.002; RVFAC, r = −0.454, P = 0.012; RVETD/LVETD, r = 0.543, P = 0.002).ConclusionsThe echocardiographic parameters IVA and RVETD/LVETD can reflect RVEF independently regardless of hemodynamics in patients with PAH. In addition, TAPSE, S’, RVFAC and RVETD/LVETD can also reflect PVR in PAH patients.

Cardiovascular parameters of computed tomographic pulmonary angiography to assess pulmonary vascular resistance in patients with chronic thromboembolic pulmonary hypertension

ObjectivesThe purpose is to identify the role of cardiovascular parameters of computed tomographic pulmonary angiography (CTPA) to assess pulmonary vascular resistance (PVR) in patients with chronic thromboembolic pulmonary hypertension (CTEPH). BackgroundThe assessment of PVR is of great importance in the management of patients with CTEPH. The role of CPTA in assessment of PVR of CTEPH remains to be explored. MethodsClinical and radiological data of 90 patients (55 men, age 17–84years) with CTEPH were retrospectively reviewed in this study. All patients received CTPA before right-heart catheterization. Cardiovascular parameters and Pulmonary Artery Obstruction Indices including Qanadli Index and Mastora Index were evaluated on CTPA. Hemodynamic PVR was calculated with the standard formula according to data from right-heart catheterization. The correlation of cardiovascular parameters of CTPA and PVR was analyzed. ResultsIn Cardiovascular parameters, neither Qanadli Index(r=0.134, p=0.208) nor Mastora Index (r=0.149, p=0.90) did correlate with PVR. Cobb angle(r=0.613, p=0.000), the ratio of right to left ventricular area(r=0.422, p=0.000)and the ratio of right to left ventricular transverse diameter (r=0.410, p=0.000) respectively correlated with PVR. By receiver operating characteristic curve analysis, a Cobb angle cutoff value of 67.55° had a sensitivity of 72.5% and a specificity of 84.0% to determine PVR ≥1000 (dyn.sec/cm5) and its Area Under Curve is (0.800±0.048). By stepwise linear regression analysis, Cobb angle was only one variable (R=0.601) shown to be independently associated with PVR, leading to the following equation: PVR=25.796×Cobb angle−585.935(F=37.929, p=0.000). ConclusionThe analysis of CTPA-derived cardiovascular parameters, especially the Cobb angle, is a reliable tool for estimating PVR in patients with CTEPH, but Pulmonary Artery Obstruction Indices do not correlate with PVR.

Echocardiographic determinants of successful balloon dilation in pulmonary atresia with intact ventricular septum

Pulmonary atresia with intact ventricular septum (PA-IVS) is a complex congenital heart malformation with multitude therapeutic approaches. Recently, balloon valvotomy has been used as an alternative to primary surgery. This study aimed to identify echocardiographic markers of balloon dilation success in PA-IVS. The echocardiograms of 26 patients diagnosed with PA-IVS who underwent primary pulmonary balloon valvotomy were reviewed. Tricuspid annulus Z-score, pulmonary annulus Z-score, right ventricular (RV) to left ventricular (LV) length ratio, RV to LV transverse diameter ratio, and tricuspid valve (TV) to mitral valve (MV) annulus diameter ratio were measured. The tricuspid Z-score, pulmonary Z-score, RV/LV length ratio, RV/LV diameter ratio, and the TV/MV ratio were significantly different in the group which had successful balloon dilation compared with that failed. Based on decision trees using the Weka classifier package, only RV/LV diameter ratio >0.76 predicts a 92.3% success rate. In contrast, an RV/LV diameter ratio < or =0.76 associated with RV/LV length ratio < or =0.70 predicts 100% failure. Successful balloon dilation in membranous type PA-IVS can be predicted by a scoring system using RV/LV diameter ratio and RV/LV length ratio.

Left ventricular endocardial longitudinal and transverse changes during isovolumic contraction and relaxation: a challenge

Left ventricular (LV) longitudinal and transverse geometric changes during isovolumic contraction and relaxation are still controversial. This confusion is compounded by traditional definitions of these phases of the cardiac cycle. High-resolution sonomicrometry studies might clarify these issues. Crystals were implanted in six sheep at the LV apex, fibrous trigones, lateral and posterior mitral annulus, base of the aortic right coronary sinus, anterior and septal endocardial wall, papillary muscle tips, and edge of the anterior and posterior mitral leaflets. Changes in distances were time related to LV and aortic pressures and to mitral valve opening. At the beginning of isovolumic contraction, while the mitral valve was still open, the LV endocardial transverse diameter started to shorten while the endocardial longitudinal diameter increased. During isovolumic relaxation, while the mitral valve was closed, LV transverse diameter started to increase while the longitudinal diameter continued to decrease. These findings are inconsistent with the classic definitions of the phases of the cardiac cycle.

Echocardiographic Predictors of an Adverse Response to a Nifedipine Trial in Primary Pulmonary Hypertension: Diminished Left Ventricular Size and Leftward Ventricular Septal Bowing

The clinical course in primary pulmonary hypertension (PPH) is improved by calcium channel blocker therapy in those with a favorable hemodynamic response during a trial of high-dose oral nifedipine. Although trials of nifedipine are performed only in patients who demonstrate pulmonary vasodilator reserve to short-acting agents, this response does not predict the safety of nifedipine treatment, which can result in severe first-dose hypotension and death. To identify echocardiographic parameters that predict first-dose nifedipine-induced hypotension in patients with PPH. The pretrial echocardiograms of 23 consecutive PPH patients (mean age, 42.3 +/- 13 years; 77% female) undergoing evaluation of pulmonary vasodilator reserve with nifedipine were analyzed. Patients were classified as those who suffered first-dose nifedipine hypotension (group 1) and those who did not (group 2). Echocardiographic measures of chamber size and septal geometry in the two groups were compared. Five measures reflecting diminished left ventricular (LV) size and leftward ventricular septal bowing were found to be associated with nifedipine hypotension: LV transverse diameter in systole (LVDs; p = 0.007), LV transverse diameter in diastole (LVDd; p = 0.05), LV area in systole (LVAs; p = 0.009), LV area in diastole (LVAd; p = 0.03), the ratio of RV to LVAs (p = 0. 02), and leftward ventricular septal bowing (p = 0.01). The LV dimensions found to best predict nifedipine-induced hypotension were LVDs < 2.7 cm, LVDd < 4.0 cm, LVAs < 15.5 cm(2), and LVAd < 20.0 cm(2). Readily available echocardiographic parameters in patients with PPH are predictive of nifedipine-induced hypotension, and can be used to select patients in whom a trial of nifedipine should be avoided.

Left ventricular remodelling in the year after myocardial infarction

The factors that influence infarct expansion early after myocardial infarction have been identified; however, there is less information about late-phase left ventricular enlargement. This study was designed to identify the clinical, haemodynamic, echocardiographic, and radionuclide angiographic criteria that predict the progress of left ventricular dilation after discharge for a first-anterior myocardial infarction. Sixty-seven patients with first Q-wave acute anterior myocardial infarction not treated with thrombolytic agents underwent baseline echocardiographic, haemodynamic, and radionuclide angiographic evaluation 4-7 days after the onset of symptoms. The echocardiographic and radionuclide evaluations were repeated after 1 year in the 55 patients who completed the follow-up. By multivariate stepwise linear regression analysis, left ventricular end-diastolic volume after 1 year and change from baseline were modelled as a function of baseline left ventricular end-diastolic volume and other potential predictors. A model including left ventricular end-diastolic pressure, global wall motion score, baseline left ventricular end-diastolic volume, and a Thrombolysis in Myocardial Infarction (TIMI) score of 0-1 was able to predict 84% of the left ventricular end-diastolic volume at the follow-up; a TIMI score of 0-1, the transverse end-diastolic diameter, global wall motion score, and the number of coronary vessels with 70% stenosis accounted for 81% of the variation in left ventricular end-diastolic volume from baseline, while the transverse end-diastolic diameter was inversely related to this parameter. The results of this study demonstrate that after an anterior myocardial infarction, the patency of the infarct-related artery is the major determinant of late left ventricular dilation, while left ventricular end-diastolic pressure influences early left ventricular dilation and baseline end-diastolic volume. Therefore, to improve left ventricular remodelling, it appears necessary to increase the patency of the infarct-related artery and improve the diastolic loading of the left ventricle at an early stage in the infarction. The inverse relationship between baseline left ventricular transverse diameter and the change in left ventricular volume after discharge indicates that the higher the baseline left ventricular volume, the less it changed during the follow-up. The global wall motion score appears to be a non-invasive parameter that is useful for identifying patients with a high risk of progressive left ventricular dilation.

Long-term canine model for echocardiography

A reliable long-term canine model for the echocardiographic evaluation of myocardial dimensions has not been previously described. Because of the configuration of the dog's chest wall, surface echocardiography is difficult to perform. Therefore, a small ultrasound transducer was designed for both short- and long-term experimental studies. In six dogs, a 1.7 by 0.5 cm, 2.25 megahertz lead titanate-zirconate echo transducer was sutured to the anterior epicardial surface of the right ventricle. The transducer was positioned to measure septal thickness, left ventricular posterior wall thickness and left ventricular transverse diameter in a manner similar to that used in clinical echocardiography. The animals were studied 2 weeks to 3 months postoperatively in the closed chest unanesthetized state. Echocardiographic determinations of septal and left ventricular wall thickness were in close agreement with results obtained at necropsy.

Measurement of internal left ventricular diameter by a tracking sonomicrometer.

An ultrasonic system for the measurement of internal left ventricular transverse diameter in animals is described. The ventricular endocardial transducers are implanted easily and with minimal trauma via the left atrium. A tracking gate, instead of a conventional threshold detector, is used to follow the received signal. Reliable signals, including the first derivative of diameter, have been obtained in 90% of subjects.