Right and left ventricular function was assessed at cardiac catheterization in 33 asymptomatic patients 0.5 to 11 years (mean 4.6) after the Mustard operation for complete transposition of the great arteries. Ages at operation had ranged from 0.5 to 16 years (mean 4.2 years). Right ventricular function was assessed using videodensitometric determination of ejection fraction and ventricular volume data. Ventricular volumes were obtained by computerized video analysis utilizing Simpson's rule. The right ventricular ejection fraction was 37 +/- 11 percent (standard deviation), as assessed with videodensitometry and 42 +/- 10 percent as assessed with ventricular volume--both values less than normal (P less than 0.001). Right ventricular end-diastolic volume was significantly greater than normal (P less than 0.001) and averaged 202 +/- 70 percent, but left ventricular end-diastolic volume averaged only 125 +/- 53 percent. These observations after the Mustard operation indicate that right ventricular function is seriously decreased with relatively preserved left ventricular function. They support efforts for surgical correction utilizing the left ventricle as the systemic ventricle.

Right and left ventricular function after the Mustard procedure in transposition of the great arteries.

A high-fidelity video digitizer/processor extracts spatial and gray-scale information from high resolution dynamic video imagery. The 15-MHz bandwidth 60/s images(fields) are low pass filtered to minimize aliasing and digitized in real-time at 20 million samples pe second (MS/s), 9 bits/sample; sequential fields are transferred to memory, retrieved from memory after computer image processing, and reconstituted at up to 40 MS/s into 60 field/s video of 525, 875, or 1225 lines/frame (two interlaced fields). A/D and D/A converters are synchronized with memory by a high-speed interface, composed of a central data interchange (DI), and 8 rarially connected I/O ports. The DI connects the data paths of one or more ports, each communicating with one or more external devices. Separate 16-bit, 40 megawords/s, input and output data buses between each port and the DI allow data entry through any port to the DI and output from the DI through any port(s), even the same port from which the input originated. The A/D and D/A are served by a single port. Two other ports communicate with CDC 3500 and CDC 1700 computers. Yet another port controls up to two megawords of core/solid-state memory, of which 358K word may be accessed at the full data rate. Storage rates into existing memory of 40 MS/s are achieved for 16-32 ms.

A Real-Time Hardware System for Digital Processing of Wide-Band Video Images

Conventional methods for calculating left ventricular (LV) ejection fraction (EF) require accurate edge definition and geometric assumptions, which may be compromised in the presence of dyssynergy. Computer densitometric analysis (CDA) of digital subtraction angiography offers the potential for calculation of EF, independent of LV shape, by comparing summated brightness for regions of interest at end diastole and end systole. Therefore, the accuracy of CDA was validated for 2 mechanical heart models of differing geometry, spherical and rectangular. Both models confirmed the close correlation between calculated and measured EF (r = 0.98 and r = 0.99, respectively). Subsequently, the CDA was compared with single and biplane area-length EF calculations in 72 patients, half with a previous myocardial infarction. In patients without previous myocardial infarction, CDA correlated closely with both single-plane and biplane EF (r = 0.91 and 0.93, respectively). The close correlation was maintained regardless of whether CDA was applied to direct LV injection or intravenous digital subtraction angiography. However, in 36 patients with previous myocardial infarction, CDA correlated less closely with single-plane (r = 0.74) than with biplane (r = 0.86) area-length EF. Thus, CDA permits calculation of EF without geometric assumptions, and may be superior to the area-length method in patients with LV dyssynergy after myocardial infarction.

Determination of left ventricular ejection fraction by computer densitometric analysis of digital subtraction angiography: Experimental validation and correlation with area-length methods

New Horizons for Study of the Cardiopulmonary and Circulatory Systems

Contrast echocardiography is a sensitive indicator of intracardiac shunts. It has allowed the precise definition of the site of intracardiac shunts and visual, subjective assessment of shunt size [1, 2]. A photometric analysis of two-dimensional echocardiography has demonstrated indicator-dilution type curves for assessment of appearance and disappearance with time [3]. Previously, our group [4] reported an attempt to quantitatively assess shunt size. We applied computer-based roentgen videodensitometric techniques to video recordings of contrast two-dimensional echocardiography to quantitate left-to-right shunts. For this preliminary study, patients with ventricular septal defect were selected for assessment of shunt size, because comparative data would be available during cardiac catheterization [4]. For contrast two-dimensional echocardiography, indocyanine green dye (1 ml) with a sahne flush was selectively injected by catheter into the left ventricular cavity. Parasternal long-axis and short-axis scans, as well as subxiphoid and suprasternal scans, were recorded with sequential dye injections. Two-inch videotape recordings were obtained and subsequently transferred to video disc for replay.

Videodensitometric Quantitation of Left-to-Right Shunts with Contrast Echocardiography

Left ventricular ejection fraction and values proportional to mitral and aortic flow were measured throughout the cardiac cycle by videodensitometric analysis of left ventricular roentgen angiograms. The technique was used simultaneously with measurement of the dimensions of the ventricle to provide absolute values for comparison. Sensitivity of the technique was tested by the ability to detect the atrial contribution to mitral flow and left ventricular chamber volume. Roentgen videodensitometry has the advantages that much information can be extracted from videoangiograms in real-time (on-line, if need be), it requires relatively low concentration of contrast medium, and it is self-calibrating.

Joachim H. Bürsch

Papers

Videodensitometric determination of left ventricular ejection and filling characteristics.