An automated method for the measurement of ventricular volume

Automatic contour definition on left ventriculograms by image evidence and a multiple template-based model

An algorithm which utilizes digital image processing and pattern recognition methods for automated definition of left ventricular (LV) contours is presented. Digital image processing and pattern recognition techniques are applied to digitally acquired radiographic images of the heart to extract the LV contours required for quantitative analysis of cardiac function. Knowledge of the image domain is invoked at each step of the algorithm to orient the data search and thereby the complexity of the solution. A knowledge-based image transformation, directional gradient search, expectations of object versus background location, least-cost path searches by dynamic programming, and a digital representation of possible versus impossible ventricular shape are exploited. The digital representation, composed of a set of characteristic templates, was created using contours obtained by manual tracing. The algorithm was tested by application of three sets of 25 images each. Test set one and two were used as training sets for creation of the model for contour correction. Model-based correction proved to be an effective technique, producing significant reduction of error in the final contours.

Variability and reproducibility of quantitative left ventricular angiography

To evaluate the reproducibility of left ventricular angiography for the assessment of left ventricular (LV) function and regional wall motion, two ventriculographies were performed in the 30 degrees right anterior oblique (RAO) projection, at 15-minute intervals, in 19 patients undergoing coronary angiography. Heart rate, left ventricular systolic pressure, and end-diastolic pressure were measured 15 minutes after the first angiography returned to the baseline values (71.0 +/- 14.1 vs. 72.2 +/- 15.5 beats/minute, 153.6 +/- 18.0 vs. 152.8 +/- 19.9 mm Hg, 21.7 +/- 8.6 vs. 20.9 +/- 7.3 mm Hg, respectively). Global and regional LV performance was analyzed by two observers with a computer-assisted technique. Intraobserver mean variation of end-diastolic volume and ejection fraction was less than 3% of the control value. Interobserver mean variations for the same parameters were less than 4% of control values. For both observers, there was no significant variation of LV end-diastolic volume and ejection fraction from one study to the other. Under stable hemodynamic conditions, the mean observed variations were, depending on the observer, 5-6% of the control value for LV end-diastolic volume and 5% for ejection fraction. Analysis of segmental wall motion was also highly reproducible. The mean intraobserver variation (% of control value) of wall motion ranged from 4.4% to 9.2%, depending on the sectors studied. The mean interobserver variation, whatever the sector, ranged from 6.9% to 13.5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular features of homozygous familial hypercholesterolemia: analysis of 16 patients

Familial hypercholesterolemia (FH) is characterized by an autosomal codominant inheritance, an abnormality in low-density lipoprotein (LDL) receptor function, elevated plasma cholesterol levels and premature atherosclerosis. Sixteen patients with homozygous FH were studied to correlate the extent of their atherosclerotic disease with their lipid levels and receptor function. The age range at initial presentation was 3 to 38 years (mean 12), and at the last examination, 6 to 43 years (mean 20). The mean pretreatment total plasma cholesterol concentration for all patients was 729 +/- 58 mg/dl (+/- standard error of the mean), and the mean LDL cholesterol level was 672 +/- 58 mg/dl (normal 60 to 176). High-density lipoprotein cholesterol was 28 +/- 3 mg/dl (normal 30 to 74). In the 7 patients with FH who had symptoms of myocardial ischemia (Group I), the mean pretreatment LDL cholesterol value (817 +/- 62 mg/dl) was higher than that of the 9 asymptomatic patients (Group II) (560 +/- 74 mg/dl). In Group I, 5 of 7 patients had left or right coronary ostial narrowing and 3 had significant left ventricular outflow obstruction. Most coronary arterial narrowing occurred in the right coronary and left anterior descending arteries and the least amount in the left circumflex coronary artery. A femoral bruit was the physical finding that correlated best with the Group I population; brother:sister pairs revealed a milder clinical course for the female. Seven of the 16 patients have survived into their third decade without symptoms. Comparison of these persons with those in whom angina developed reveals a marked heterogeneity in their clinical course, which appears to be associated with receptor negative/defective status.

Prognosis of asymptomatic or mildly symptomatic patients with coronary artery disease

One hundred forty-seven asymptomatic or mildly symptomatic patients with coronary artery disease, who did not have significant left main coronary occlusion and had an ejection fraction greater than 20 percent, were followed up prospectively for 6 to 67 months (average 25). Significant obstruction of one coronary artery was present in 28 percent of patients, of two coronary arteries in 31 percent and of three coronary arteries in 41 percent. Ejection fraction was 55 percent or greater in 69 percent of patients. During the follow-up there were eight deaths (annual mortality rate 3 percent for the entire group, 1.5 percent for patients with single and double vessel disease but 6 percent for those with triple vessel disease). Better definition of high and low risk subgroups of patients with three vessel disease was accomplished with exercise testing. Despite a history of mild symptoms, 25 percent of the patients with triple vessel disease exhibited poor exercise capacity on exercise testing after administration of beta adrenoceptor blocking agents and nitrates was discontinued; of these, 40 percent either died (20 percent) or had progressive symptoms requiring operation (20 percent) (annual mortality rate 9 percent). Of the patients with good exercise capacity, only 22 percent either died (7 percent) or had progressive symptoms (15 percent) (annual mortality rate 4 percent). Thus, prognosis is excellent in patients with no or mild symptoms who have one or two vessel coronary disease. Patients with three vessel disease who have good exercise capacity documented by objective testing have an annual mortality rate of 4 percent. However, because patients with three vessel disease and poor exercise capacity have an extremely grave prognosis, it would appear reasonable to recommend coronary bypass surgery for this subgroup, even in the absence of supporting data derived from a definitive randomized study.

Comparison of digital boundary detection and semi-automated analysis of left ventricular cine angiograms

A technique has been developed to analyze automatically 35 mm left ventricular cine angiograms with an image dissector and digital computer. The analysis procedure detected the ventricular boundary and aortic valve position, then calculated the projected left ventricular area and estimated volume, and performed a polar wall motion analysis as a function of time. The automated method was compared to a semi-automated method using a technician-operated electronic cursor linked to a mini-computer. The two methods were used to analyze a set of idealized ventricular models as well as normal and abnormal angiographic data. The volumetric and wall motion data for the idealized models calculated by the two methods were equivalent (r greater than 0.99). Volumetric analysis of the patients' ventriculograms produced correlation coefficients of 0.88-0.99. Corresponding wall motion data produced correlation coefficients of 0.72-0.94. The time necessary to analyze 30 frames of cine ventriculogram was approximately 30 minutes for each method.

Error propagation in quantitative biplane cineroentgenography

The propagation of errors in quantitative biplane cineroentgenography was investigated to see which variables were the most critical. The analysis was carried out both for the propagation of root-mean-square errors and for errors as derived by a Taylor expansion of the reconstruction equations. The reconstruction is most sensitive to the measured values of the coordinates, as opposed to the parameters of the physical system. It was found that decreasing the error in one parameter to zero does not significantly affect the accuracy of the reconstruction; it is more efficient to reduce the errors for all of the parameters simultaneously.

Automatic data processing in the cardiac catheterization laboratory

A review of automatic data processing in the cardiac catherization lab is presented. The emphasis placed on on-line manometry, indicator dilution and off-line quantitative ventriculography. The system organization is described and several specific examples given to illustrate the level of detail necessary to specify such a system. The clinical use of the system is described together with an evaluation of the original design goals in terms of the actual performance of the system. A few unexpected benefits have emerged with respect to quality control and reliability, but one of the original design goals, speeding up the catheterization procedure, has proven to be unrealistic. The next logical steps in the software and hardware evolution are described with the emphasis placed on making the system a more effective tool for the clinician.

Real-time radionuclide cineangiography in the noninvasive evaluation of global and regional left ventricular function at rest and during exercise in patients with coronary-artery disease

Although coronary angiography defines regions of potential ischemia in patients with coronary-artery disease, accurate assessment of the presence and functional importance of ischemia requires appraisal of regional and global left ventricular function during stress. To perform such assessment, we developed a noninvasive real-time radionuclide cineangiographic procedure permitting continuous monitoring and analysis of left ventricular function during exercise. In 11 patients with coronary disease who had normal regional and global ventricular function at rest, new regions of dysfunction developed during exercise (P less than 0.001), and in 10, global ejection fraction dropped 7 to 47 per cent. Fourteen age-matched normal subjects were studied; during exercise none had regional dysfunction, and each increased global ejection fraction (average increase, 23 +/- 3 per cent [+/-S.E.], P less than 0.001 as compared with patients with coronary disease). Radionuclide cineangiography during exercise permits accurate assessment of the presence and functional severity of ischemic heart disease.

Prognostic implications of left ventricular function in endomyocardial disease in infants and children

Hemodynamic factors measured at cardiac catheterization in 40 infants and children with chronic endomyocardial disease were analyzed in regard to subsequent clinical condition. The patients were followed for periods ranging from 2 months to 11 years (average 4.3 years) after initial cardiac catheterization. There were no statistically significant differences in left ventricular end-diastolic volume among survivors with no symptoms, survivors with persistent congestive heart failure, and nonsurvivors. Ejection fractions were depressed in about four fifths of patients with chronic endomyocardial disease and were significantly lower in the group of patients who died subsequently. LVEDP in patients who did not survive was significantly higher than in asymptomatic survivors, but there was too much overlapping of individual values to be of prognostic value. Left ventricular pressure-volume loops appeared to offer an improved, although more tedious, method of assessing LV function. In addition to offering information on LVEDV, LVEDP, and EjF, LV stroke work may easily be estimated from pressure-volume loops. There was generally good correlation between hemodynamic status assessed from pressure-volume loops and subsequent clinical outcome.

Quantification of ventricular performance: a computer-based system for the analysis of angiographic data

A computer-based quantitative angiography system for the acquisition and analysis of ventriculographic data has been developed. In addition to the apparatus normally required for angiography and left ventricular pressure recording, a digitizing tablet, PDP 11/20 mini computer, and TV monitor with a hard-copy device is employed. Four modes of operation are currently in use: data acquisition, analysis, mini cine, and data tape editor. Data acquisition facilitates forming a magnetic tape record of the digitized pressure, timing, and event identification, together with anywhere from 4 to 100 digitilized LV contours. A number of error checks and feedbacks are incorporated to provide some measure of quality control. In the event an error is written onto the magnetic tape record, the data tape editor can be used to review the record and correct most errors. Analysis of the generated data tape consists of several options which include: pump function, muscle function, pressure derived indices of contractility and systolic time intervals, and contour pattern recognition which is still under development. If the complete analysis option is chosen, a summary of the analysis, referred to as the quick-sight list, is also presented. The so called mini cine option employs a separate and independent acquisition-analysis program. This requires only the end-diastolic (with a segment of wall) and end-systolic contours (without pressure data) to extract the most essential parameters (EDV, EF, CI, HR, and wall mass). As a result of the relative straightforward processing and inherent simplicity, the mini cine option is most frequently used. This system has done much to reduce the time required for analysis of angiographic data, while at the same time maintaining and even improving the quality of the results. Other less tangible benefits include: the possibility to build a readily accessible library of patient data files facilitating a posteriori studies, precise and uniform definition of the rules to input and analyze data, and finally providing a useful step towards fully automatic ventriculographic processing.