The clinical value of ultrasonic tissue characterization in the management of heart transplant patients

The purpose of this study was to evaluate the rejection process by ultrasonic tissue characterization. Serial 2D echocardiographic images were obtained within 24 h prior to an endomyocardial biopsy. The end-diastolic echoframes were digitized into a computer matrix. A region of interest was placed into the anteroseptal segment of each scan. Image texture was analysed by four major groups of texture analysis (first-order histogram, co-occurrence matrix, run-length statistic, power spectrum). In 23 patients, 408 biopsies were taken after each examination, so that correlation between the ultrasonic tissue measurements and the histological state of the tissue could be determined. When rejection occurred, heterogeneity, brightness and contrast of texture increased. Of 117 texture parameters originally claculated, three parameters (inverse difference moment, run-length non-uniformity, ring sums of power spectrum) that characterized rejection were determined by means of discriminance analysis. Compared with biopsy findings, echocardiographic sensitivity for moderate rejection was 93.3% and specifity 83.6%. Our study indicates that acute rejection is associated with changes in echocardiographic texture. Serial echocardiographic texture analysis can reliably identify heart transplant rejection.

Transmyocardial laser revascularization in ischemic cardiomyopathy

BACKGROUND

In ischemic cardiomyopathy (left ventricular ejection fraction [LVEF] < or = 30%), myocardial revascularization by coronary artery surgery has better results than heart transplantation, provided there is sufficient ischemic but viable myocardium. The mode of action of transmyocardial laser revascularization (TMR) is still being debated, but if the procedure induces improved myocardial perfusion it could be a "bridge," or alternative, to heart transplantation.

METHODS

We retrospectively analyzed 194 patients, who underwent TMR between July 1997 and October 1999. Patients with TMR as an adjunct to coronary artery surgery (n = 30) and those who did not provide written consent to the procedure (n = 8) were excluded; 126 patients had normal or moderately reduced left ventricular function, and 30 patients with ischemic cardiomyopathy (LVEF < or = 30%) were included.

RESULTS

After 12 months, the Canadian Cardiovascular Society (CCS) score dropped significantly from 3.6 (3 to 4) to 2.4 (1 to 4) and maximum work load increased significantly from 58 W (25 to 100 W) to 73 W (25 to 120 W). However, thallium score and LVEF did not improve significantly (27% [15% to 30%] to 32% [15% to 45%]). Prior to the TMR procedure, all 30 patients had a "low risk" or "medium risk" of death according to the Aaronson classification. The 30-day, 1-year, and 2-year survival rates were 83%, 50%, and 47%, respectively.

CONCLUSIONS

We conclude that TMR in ischemic cardiomyopathy (LVEF < or = 30%) has a perioperative risk comparable to that for heart transplantation, but there is no improvement of myocardial performance or life expectancy. Therefore, TMR cannot be regarded as a "bridge," or alternative, to transplantation. However, in individual cases with contraindications for transplantation the anti-anginal effect may justify use of the procedure.

Measuring left ventricular function after heart transplantation via digitization of M-mode echocardiograms

The aim of the study was to assess the usefulness of M-mode echocardiography for noninvasive diagnosis of cardiac rejection. For this purpose, 292 M-mode images of 26 heart transplant recipients were analyzed. The echocardiographic images were digitized into an image analysis system. The curves of left ventricular diameter changes were obtained and its first differential calculated. A total of 23 parameters were measured. The most important parameters were: peak velocity of systolic diameter change, peak velocity of diastolic diameter change, time to peak velocity of systolic diameter change, time to peak velocity of diastolic diameter change (TPEAK-D), isovolumetric relaxation time (IVRT), rapid filling time (RFT), shortening fraction (SF), and mean velocity of circumferential fiber shortening (MVCF). The echocardiographic parameters were compared to biopsy results. In 18 patients, 23 biopsy-proven moderate rejections occurred. When rejection occurred, IVRT decreased 23% +/- 6% (P < 0.05), SF decreased 13% +/- 14% (P<0.05), MVCF decreased 18% +/- 18% (P<0.05), and TPEAK-D increased 27% +/- 27% (P<0.05). We concluded that the analysis of digitized M-mode images can identify heart transplant rejection.

Transmyocardial laser revascularization in the treatment of end-stage coronary artery disease

Transmyocardial laser revascularization has been used in 171 patients suffering from severe angina pectoris unresponsive to medical therapy at Deutsches Herzzentrum Berlin within the period from 7/1994 to 12/1997. In all patients conventional bypass surgery or PTCA, did not seem to offer the possibility of success. Postoperatively, the majority of the patients experienced a significant decrease in angina and better physical endurance. A statistically significant increase in myocardial perfusion or left ventricular contractility has not been detected. Perioperative mortality after TMR decreased from 8% among the first 40 patients to 2.5% among the 40 patients operated on most recently, with an overall mortality of 7%. The relief of angina symptoms and the improved quality of life after TMR seems to justify the use of the method in patients who presented with urgent indications for CABG surgery, although their coronary vessel status did not seem to promise success for this procedure. However, considering its experimental foundation and long-term effects, it seems that a conclusive assessment of TMR is not yet possible.

Secondary transmyocardial laser revascularization in the treatment of end-stage coronary artery disease

Transmyocardial laser revascularization (TMR) has received more acceptance within the last few years. The vast majority of TMR users report impressive clinical benefits. The underlying mechanism for benefit by TMR, however, remains somewhat unclear. Between July 1994 and September 1997, 165 patients underwent TMR at our institution. In three of our TMR patients after an initial angina-free interval of 1 to 2 years we decided to repeat the laser operation. This article focuses on the three re-TMR patients who underwent a second TMR operation 12 to 14 months after the first one. Two of the three patients are well and experience significantly less angina than preoperatively.

Clinical value of echocardiographic tissue characterization in the diagnosis of myocarditis

Inflammatory changes in the myocardium have been visually observed as alterations on echocardiograms. The goal of this study was to determine how these myocardial changes affect the texture of echocardiographic images, and how these could be described through quantitative texture analysis. The results of 142 endomyocardial biopsies were compared with those of texture analysis in echocardiograms of 106 patients suspected of having myocarditis. There were 52 cases of biopsy-proven acute myocarditis, 12 of persistent myocarditis, nine of healed myocarditis without fibrosis, 17 of healed myocarditis with fibrosis, and 35 cases of cardiomyopathy. Eight myocardial biopsies exhibited no pathological changes and nine patients had other cardiac problems. The echocardiograms of a control group of 24 healthy subjects were also evaluated by texture analysis. Three texture parameters were able to differentiate between normal and abnormal myocardium. The mean grey value, i.e. average brightness, was appreciably higher in cases of myocarditis than in control subjects, whereas one co-occurrence and one run length feature had markedly decreased. We conclude that myocarditis and fibrosis induce changes in echocardiographic image texture, i.e. increases in brightness, heterogeneity, and contrast. Performing digital image texture analysis of echocardiograms makes it possible to distinguish between myocarditis and normal myocardium.

Noninvasive diagnosis of cardiac rejection through echocardiographic tissue characterization

Ultrasonic tissue characterization is based on the assumption that microscopic tissue structures are identifiable by their acoustic properties. Our study group consisted of 23 cardiac recipients. Two-dimensional images were obtained within 2 hours of endomyocardial biopsy. The end-diastolic echo frames were digitized into the matrix of an image-processing system. A region of interest was placed into the anteroseptal segment of the left ventricle. The texture within the region of interest was analyzed using four major groups of texture analysis (first-order histogram, co-occurrence matrix, run-length statistic, and power spectrum). A total of 408 echocardiographic examinations were compared with histologic findings. The 117 initially calculated texture parameters were reduced incrementally using a series of discriminant analyses. A set of three texture parameters (inverse difference moment undirected, run-length nonuniformity vertical, and sector sum) was able to describe changed echocardiographic texture when rejection occurred. Using these three parameters, echocardiographic sensitivity was 89.0% and specificity was 83.6% for moderate rejection. We conclude that cardiac rejection is associated with echocardiographic texture alterations and that serial echocardiographic texture analysis can reliably identify rejection.

Clinical heart transplantation without routine endomyocardial biopsy

In a prospective clinical study, routine endomyocardial biopsy (EMB) for early detection of cardiac allograft rejection was replaced by two noninvasive diagnostic techniques. In 32 patients who underwent transplantation during a 6-month period, intramyocardial electrogram (IMEG) amplitude was recorded with the telemetry function of a dual-chamber pacemaker system. An amplitude decrease of more than 8% below the individual range of variability in overnight long-term recordings served as an indicator of rejection. A prolongation of the time interval Te--the time span between maximal posterior wall contraction and peak retraction velocity--of more than 20 msec was used as an additional indicator of rejection-related left ventricular dysfunction. For patient safety, routine EMBs were still performed but remained undisclosed to the transplantation team. The pathologist was asked to intervene in cases of discrepancies between biopsy results and medical decisions, but no such intervention was necessary. Twenty-seven rejection episodes were treated medically, of which 22 were diagnosed noninvasively. In four patients, EMB, ordered because noninvasive parameters remained inconclusive, led to medical treatment. No false negative IMEG results were observed. Retrospective correlation with rejection gave a 100% negative predictive value for IMEG and a 96.9% negative predictive value for echocardiographic diagnosis. We conclude that omission of a schedule of routine biopsies is justified, if the described techniques of IMEG and echocardiography are meticulously applied and indicate normal cardiac function. EMB remains indicated if noninvasive parameters are not conclusive or if false-positive IMEG results, which were observed in the presence of infection or arrhythmias, are suspected. The frequency of EMB can be reduced by 90%, compared to conventional routine biopsy schedules. Diagnostic safety is increased because the additional information gained from IMEG and echocardiography is helpful in the interpretation of EMBs.

[Ultrasound sonographic diagnosis of myocarditis using quantitative texture analysis of 2-dimensional echocardiography images]

In a prospective study we tested the possibility to differentiate myocardial tissue by means of the quantitative texture analysis of two-dimensional echocardiographic images. 12 patients with a bioptically ascertained myocarditis and 12 healthy patients of a control group were echocardiographically examined. The results demonstrated that the echocardiographic image texture in myocarditis is characterized by an increase of the texture parameters entropy, second difference moment and long-run emphasis as well as by a decrease of the parameters angular second moment, inverse difference moment and run-length nonuniformity as well as by different values of the ring and sector sums of the power spectre. The digital image processing of echocardiography images seems thus to open a new way to the noninvasive diagnostic of myocarditis.