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PubMed1992

Role of the septal leaflet in tricuspid valve closure. Consideration for treatment of complete atrioventricular canal.

A septal leaflet of the tricuspid valve is thought to work differently from other anterior and posterior leaflets. We studied its role in valve closure in dogs by means of a dynamic area meter. During the control state, the tricuspid valve orifice area increased twice in diastole coincidentally with either atrial systole or rapid ventricular filling. We observed several findings after the septal leaflet resection: (1) two peak area patterns of the tricuspid valve orifice in diastole, (2) no elevation of right atrial pressure on ventricular systole (there was no V wave), (3) no tricuspid valve regurgitation on right ventriculography. These findings suggest that a complete valve closure occurred without the septal leaflet in regular sinus rhythm. An elevation of the right ventricular pressure produced by pulmonary artery stenosis without septal leaflet, however, easily caused tricuspid valve regurgitation in contrast to the same pressure of the right ventricle with the normal tricuspid valve. The right ventricular pacing caused severe valve regurgitation without the septal leaflet. Results indicate that in the repair of the complete atrioventricular canal defect and other tricuspid valve lesions, the septal leaflet of the tricuspid valve rarely requires attention. An atrioventricular block should be avoided, however, because electrical cardiac pacing on the right ventricle causes severe valve regurgitation without the septal leaflet.

Animals↗
PubMed1992

[The right ventricle and tachyarrhythmias. The structural-functional characteristics studied by radionuclide ventriculography].

Radionuclide ventriculography was used to evaluate the functional structural parameters of the right ventricle systole and diastole in 100 patients with paroxysmal tachyarrhythmia without signs of cardiac insufficiency (42 with cardiac fibrillation, 35--supraventricular tachycardia, 23--with ventricular arrhythmia). Results indicate that radionuclide ventriculography allows to evaluate objectively the functional state of the right ventricle in patients with paroxysmal tachycardia, detect early signs of deterioration of its hemodynamic productivity and contractile capacity in patients refractory to treatment of cardiac arrhythmias.

Adolescent↗
PubMed1992

[Right ventricular volume determination by continuous 81mKr infusion and 99mTc blood pool imaging].

Our newly developed radionuclide method for the calculation of right ventricular (RV) volume was examined in this study. Using a semi-geometric count-based method, volume can be measured by the following equation: Cv = Cm/(L/d). V = (Ct/Cv) x d3 = (Ct/Cm) x L x d2. (V = volume, Cv = voxel count, Cm = the maximum count of a container, Ct = the total count of the container, L = maximum length of the image of the container obtained from a direction perpendicular to the direction where the count data were collected, and d = pixel size.) A phantom study was performed by setting a cylindrical container in a system which circulated 5 liters of water per minute. 81mKr solution was infused continuously into the container, and images of the container were collected for one minute. Cm and Ct were obtained and, because the container was cylindrical, the maximum width of the image of the container was measured as L. The volume of the container was calculated using the above equation. The container's true volume and the volume measured by this method showed a good correlation with r = 0.997 (n = 13, p < 0.001). This theorem was applied to RV images obtained in the 30 degree right anterior oblique position by continuous infusion of the 81mKr solution. Multiple gated acquisition was performed and RV end-diastolic maximum counts and total counts were obtained. The RV maximum width was measured as L on the end-diastolic cardiac pool image with 99mTc-D-HSA collected in the 40 degree left anterior oblique position.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Assessment of right ventricular function using gated blood pool single photon emission computed tomography in inferior myocardial infarction with or without hemodynamically significant right ventricular infarction].

Right ventricular function was assessed using gated blood pool single photon emission computed tomography (GSPECT) in 10 normal subjects and 14 patients with inferior myocardial infarction. Three-dimensional background subtraction was achieved by applying an optimal cut off level. The patient group consisted of 6 patients with definite hemodynamic abnormalities indicative of right ventricular infarction (RVI) and 8 other patients with significant obstructive lesion at the proximal portion of right coronary artery without obvious hemodynamic signs of RVI. Right ventricular regional wall motion abnormalities were demonstrated on GSPECT functional images and the indices of right ventricular function (i.e. the right ventricular ejection fraction (RVEF), the right ventricular peak ejection rate (RVPER) and the right ventricular peak filling rate (RVPFR)) were significantly reduced in the patient group, not only in the patients with definite RVI but also in those without hemodynamic signs of RVI. The present study indicates that inferior infarction is frequently associated with RVI, even in the absence of definite hemodynamic signs, when the proximal portion of right coronary artery is obstructed. It is concluded that GSPECT is reliable for the assessment of right ventricular function and regional wall motion, and is also useful for the diagnosis of RVI.

Hemodynamics↗
PubMed1991

[Radionuclide ventriculography in the diagnosis of hypertrophic cardiomyopathy].

Total and regional (by 7 zones) contractility of left ventricular functions in 25 patients with hypertrophic cardiomyopathy (HCMP) were characterized by a different combination of normal and elevated values of total and regional ejection fractions, rate indices of systolic expulsion. Normal or slightly changed values of the end-diastolic volume were combined with normal or elevated values of the stroke volume. Comparative analysis of the values characterizing cardiodynamics, led to working out criteria of differential diagnosis in HCMP patients with heart pain and in CHD patients with myocardial hypertrophy (predominance of the signs of left ventricular hyperfunction in the former and contractility hypofunction and asynergy in the latter). Changes in the diastolic filling of the left ventricle indicated its disturbed diastolic function in both groups of patients.

Adolescent↗
PubMed1991

[Primary cardiac tumor with singular findings on cardiac radionuclide scintigraphy].

We encountered a primary cardiac tumor originated from the right atrium or pericardium with singular findings on cardiac radionuclide scintigraphy. The patient was 43-year-old female who showed asymptomatic cardiomegaly and abnormal cardiac silhouette by chest X-ray. First pass radionuclide angiography using Tc-99m pertechnetate revealed the abnormal stain filled from the stem of ascending aorta inner and outer portion of the right atrium. Selective angiography showed that the main feeding artery of the tumor was right coronary artery and right internal mammary artery. The pathological diagnosis of the surgically resected specimen was angiosarcoma. It was suggested that detail evaluation of first pass radionuclide angiography give us a useful clinical information linked the feeding artery of cardiac tumor in this case.

Adult↗
PubMedDate not supplied

Application of a new nuclear scintigraphy camera to evaluate flow and mechanical pumping of artificial hearts.

To assist in the development of an artificial blood pump, The Milwaukee Heart (MH-1), a new nuclear scintigraphy camera was used to study the wash-in and wash-out patterns of the MH-1. These studies indicate the MH-1 has an ejection fraction of 59.3%, with a stroke volume of 72 +/- 3 ml, and an afterload of 130 mmHg. Flow through the device is highly uniform, with no areas of stagnation. Regional ejection fraction images demonstrate homogeneous ejection from apex to base. The ability to scan through the first pass images allows study of wash-in, mixing, and wash-out of the tracer. In conclusion, this technique may provide a new approach to evaluating artificial heart pumps.

Blood Flow Velocity↗
PubMed1991

[Right ventricular function in sleep apnea syndrome and chronic obstructive pulmonary disease].

The factors that contribute to the development of chronic cor pulmonale (CCP) in sleep apnea syndrome (SAS) are being continuously reviewed, as well as the role played by the coexistence of chronic obstructive pulmonary disease (COPD). Right ventricular function was evaluated in 20 SAS patients, 10 of whom presented associated (COPD). In all of them the following tests were performed while fasting: blood gasometry, spirometry, body mass index and isotopic ventriculography which included the determination of righ ventricular ejection fraction (RVEF). The RVEF of the group presenting COPD (mean +/- DS) (0.43 +/- 0.07) was not significantly different from the group without COPD (0.46 +/- 0.09). When the patients were regrouped according to the presence of hypoxemia during the day (paO2 less than 70 mmHg) a significant difference was evidenced between the mean value of the RVEF group with hypoxemia (n = 10) (0.40 +/- 0.02) and that of the group with normoxemia (n = 10) (0.50 +/- 0.09) (p less than 0.05). There were no statistically significant differences between the degree of obstruction and the BMI in either group. These results suggest that the worsening of RVF is more frequent in SAS patients who present daytime hypoxemia.

Adult↗
PubMed1991

Evaluation of right ventricular regional perfusion with technetium-99m-sestamibi SPECT.

To evaluate technetium-99m-sestamibi as a right ventricular perfusion imaging agent, 25 normal volunteers and 25 patients with suspected coronary disease were studied with both sestamibi and thallium-201 SPECT. All patients underwent cardiac characterization. Compared to thallium-201 images, visualization of the right ventricle was superior for sestamibi in all cases. After computer masking of the left ventricle, count profiles for each 6-mm right ventricular short-axis slice were extracted and plotted in a bull's-eye type polar map with images normalized to maximal right ventricular counts. On sestamibi right ventricular polar maps, 7 of 11 patients (64%) with right coronary stenosis had fixed or reversible inferior right ventricular defects. None of the 25 volunteers or patients without right coronary stenosis had right ventricular defects (true-negative rate = 100%). We conclude that sestamibi SPECT provides an accurate means to assess right ventricular regional perfusion, with data presentation and interpretation facilitated by the polar map display.

Adult↗
PubMed1991

[Evaluation of a single oral dose of nifedipine on the right- ventricular ejection fraction in patients with chronic obstructive lung diseases].

Nineteen patients (12 males, 7 females, mean age 59 +/- 10 years) with chronic obstructive lung disease and lowered ventilatory reserves in partial and full respiratory insufficiency (FEV1 f = 51 +/- 19%; MEF 50 = 23 +/- 13% pred. value, R(aw) = 220 +/- 120%; pO2 = 59 +/- 5; pCO2 = 41 +/- 10 mmHg) were included in the study. All had RVEF measured using radionuclide angiocardiography before and 60 minutes after oral administration of 20 mg of nifedipine. In all RVEF was initially reduced by 25%. After administration of NF in 12 patients a statistically significant increase of RVEF was seen (by a mean value of 12 = +/- 8%). iN 7 no significant increase could be seen. The two groups reactive and non-reactive to NF did not differ in age, sex, degree of ventilatory impairment, hypoxia, and initial decrease of RVEF.

Administration, Oral↗
PubMed1991

[Quantitative evaluation of right ventricular function by transesophageal echocardiography: report of a case with classical right ventricular infarction].

We were able to diagnose right ventricular infarction (RVI) by transesophageal echocardiography (TEE) in a patient with acute inferior infarction, and it was confirmed by cardiac catheterization. To evaluate right ventricular (RV) function quantitatively, area shortening (AS) and regional AS (rAS) were measured from RV images obtained by TEE. The AS correlated with RV ejection fraction obtained by radionuclide angiography (r = 0.72). The patient with RVI showed depressed RV function by AS measurement with decreased rASs of all regions in the acute phase. In the chronic phase, RV function of the patient improved, especially in the region of the ventricular septum and apex regions. These results indicate availability of TEE and that RV function can be evaluated by TEE.

Aged↗
PubMed1979

Validity of left-ventricular ejection fractions measured at rest and peak exercise by equilibrium radionuclide angiography using short acquisition times.

To validate ejection fraction (EF) calculations from 5 and 2 minutes of multiple-gated equilibrium radionuclide angiographic data and to establish its utility during alterations in cardiac performance, we studied 38 patients with chest pain suggestive of coronary artery disease. Twenty-four patients underwent contrast ventriculography (CV) as well as first-pass (FP) and equilibrium (EQ) radionuclide angiography at rest, and 14 additional patients had both radionuclide tests performed at rest as well as during peak supine bicycle exercise. The resting 5-min acquisition ejection fractions were compared between each method and the following correlations were generated: r = .92, n = 24 (CV-EQ), r = .92, n = 24 (CV-FP), and r = .95, n = 38 (FP-EQ). The variability of EQ-EF calculations between two independent observers was less than 2%; the mean absolute difference between two sequential 2-min acquisitions and the 5-min recordings was -.1 +/- 1.6%, and the reproducibility of sequential 2-min ejection fractions was excellent (r = .98). EQ and FP ejection fractions at symptom-limited exercise correlated well (r = .96, n = 14). We conclude that equilibrium radionuclide angiography is a valid method to measure EF both at rest as well as during peak exercise even when 2-min acquisition periods are used.

Adult↗
PubMed1991

Left ventricular dysfunction and blood glycohemoglobin levels in young diabetics.

Left ventricular function including regional wall motion (RWM) was evaluated by 99mTc first-pass and equilibrium gated blood pool ventriculography and glycohemoglobin (HbA1c) blood levels determined by a quantitative column technique in 25 young patients with insulin-dependent diabetes mellitus without clinical evidence of heart disease, and in healthy controls matched for age and sex. Phase analysis revealed abnormal RWM in 19 of 21 diabetic patients. The mean left ventricular global ejection fraction, the mean regional ejection fraction and the mean 1/3 filling fraction were lower and the time to peak ejection, the time to peak filling and the time to peak ejection/cardiac cycle were longer in diabetics than in controls. We found high HbA1c levels in all diabetics. There was no significant difference between patients with and without retinopathy and with and without peripheral neuropathy in terms of left ventricular function and HbA1c levels.

Adolescent↗
PubMed1992

Analysis of left ventricular function from gated first-pass and multiple gated equilibrium acquisitions.

99mTechnetium-sestamibi is a new myocardial perfusion imaging agent that offers significant physical advantages over 201thallium for myocardial perfusion imaging. One of these advantages is that it can be used in the assessment of ventricular function by means of first-pass radionuclide angiography (FPRNA), acquired during the injection of the tracer. In this study we compared gated list mode first-pass acquisition with 99mTc-sestamibi (FP-MIBI) to multiple gated equilibrium radionuclide ventriculography (MUGA) with 99mTc-labelled red blood cells for the determination of global left ventricular ejection fraction (LVEF). The study population consisted of 20 patients (mean age 54 years) who were submitted to stress-rest perfusion imaging. Resting FPRNA was performed using 99mTc-sestamibi and the reference data were acquired within a week with the MUGA technique. A linear correlation between FP LVEF and MUGA LVEF gave an r = 0.974 (p < 0.01). Diastolic and systolic timing and velocity parameters had lower correlations between these two methods. We conclude that global LVEF can be precisely measured with 99mTc-sestamibi when compared to usually employed MUGA technique with 99mTc-labelled red blood cells.

Cardiac Output↗
PubMed1978

Left-ventricular ejection fraction and segmental wall motion by peripheral first-pass radionuclide angiography.

A computerized edge-detection method was developed to obtain radionuclide ventriculograms for analysis of left-ventricular ejection fraction and segmental wall motion from first-pass studies following i.v. injection of radionuclide. The accuracy of this technique was examined in 21 patients undergoing cardiac catheterization. Tc-99m DTPA was injected into an antecubital vein, with data acquisition in the 30 degrees RAO projection by a gamma scintillation camera interfaced to a computer. A computerized profile analysis was used to determine objectively the edge of the left-ventricular blood pool. Time-activity curves were generated, and the ejection fraction was calculated from sequential end-diastolic and end-systolic count rates. The values for ejection fraction correlated well with those obtained by single-plane contrast ventriculography (r = 0.95). End-diastolic and end-systolic images were reconstructed from the time-activity curve. To analyze segmental wall motion, the left-ventricular outline was divided into five segments and the motion of each segment was graded qualitatively from 1 to 5. Seventy-five of 105 segments had the same grade as the wall motion determined by contrast angiography, and 102 of 105 were within one grade. (P less than 0.001). These findings demonstrate the accuracy of this improved technique for objective, rapid, and noninvasive determination of left-ventricular function.

Adult↗
PubMed1992

Presurgical identification of hibernating myocardium by combined use of technetium-99m hexakis 2-methoxyisobutylisonitrile single photon emission tomography and fluorine-18 fluoro-2-deoxy-D-glucose positron emission tomography in patients with coronary artery disease.

We tested the possibility of identifying areas of hibernating myocardium by the combined assessment of perfusion and metabolism using single photon emission tomography (SPET) with technetium-99m hexakis 2-methoxyisobutylisonitrile (99mTc-MIBI) and positron emission tomography (PET) with fluorine-18 fluoro-2-deoxy-D-glucose (18F-FDG). Segmental wall motion, perfusion and 18F-FDG uptake were scored in 5 segments in 14 patients with coronary artery disease (CAD), for a total number of 70 segments. Each subject underwent the following studies prior to and following coronary artery bypass grafting (CABG): first-pass radionuclide angiography, electrocardiography gated planar perfusion scintigraphy and SPET perfusion scintigraphy with 99mTc-MIBI and, after 16 h fasting, 18F-FDG/PET metabolic scintigraphy. Wall motion impairment was either decreased or completely reversed by CABG in 95% of the asynergic segments which exhibited 18F-FDG uptake, whereas it was unmodified in 80% of the asynergic segments with no 18F-FDG uptake. A stepwise multiple logistic analysis was carried out on the asynergic segments to estimate the postoperative probability of wall motion improvement on the basis of the preoperative regional perfusion and metabolic scores. The segments with the highest probability (96%) of functional recovery from preoperative asynergy after revascularization were those with a marked 18F-FDG uptake prior to CABG. High probabilities of functional recovery were also estimated for the segments presenting with moderate and low 18F-FDG uptake (92% and 79%, respectively). A low probability of functional recovery (13%) was estimated in the segments with no 18F-FDG uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗
PubMed1992

Left ventricular perfusion and performance from a single radiopharmaceutical and one camera.

To test the hypothesis that a small field of view portable multicrystal scintillation camera can perform stress/rest combined LV function by first-pass and perfusion studies using 99mTc-teboroxime, 26 patients with positive stress thallium studies within 2 wk and 8 healthy volunteers were studied. A 241Am point source marker over the sternum was used for motion correction. Dynamic dual-isotope (99mTc/241Am) acquisition was performed following injection of 15.6 +/- 2.3 mCi of 99mTc-teboroxime at peak treadmill exercise. Two minutes later (blood-pool clearance), while still standing on the flat treadmill, 3-4 40-sec planar images were acquired. One hour later patients were reinjected with 22.7 +/- 3.4 mCi of 99mTc-teboroxime while standing in front of the camera and the same dynamic/static acquisition protocol repeated. The planar images were interpolated from a 20 x 20 matrix to a 160 x 160 matrix, a sharpening filter and an interpolative background subtraction algorithm applied. The scans were divided into segments, each scored as normal, reversible and fixed. The agreement with thallium imaging for identifying an abnormal scan was 24/26 (92%) and for identifying abnormal vascular territories was 43/52, (83%). Fourteen patients had exercise LVEF less than 50% and all had either prior myocardial infarction, myocardial infarction plus ischemia or LAD ischemia. Diagnostic planar perfusion images and exercise LVEF can be acquired in less than 4 min using 99mTc-teboroxime and a portable multicrystal scintillation camera.

Adult↗