Biomedical subjects

Michael J Kelly

Publications and source records attributed to Michael J Kelly.

4 recordsLinked to original sources

PubMed2004

Demonstrating time sequence and extent of sustained decrease in native heart ejection fraction after heterotopic transplantation.

BACKGROUND: In this study we investigate the time sequence and extent of the sustained decrease in native heart ejection fraction (EF) after heterotopic heart transplantation (HHTx) when using gated cardiac blood pool scanning (GCBPS) and transthoracic echocardiography (TTE) One case report of 2 patients used post-operative GCBPS and TTE and found a significant deterioration in native heart EF post-operatively over the course of several years. Comparison with pre-operative measurements using these techniques in a series of patients has not been performed previously. METHODS: Thirteen of 16 HHTx patients with adequate pre- and post-operative GCBPS follow-up were included in this study. All patients also underwent TTE post-operatively and the GCBPS results were correlated with the TTE findings. RESULTS: GCBPS demonstrated a marked (21.1 +/- 4.7% vs 10.5 +/- 3.7%, p < 0.0001) decrease in native EF post-HHTx. Spontaneous echo contrast in the native left ventricle and/or poor opening of the mitral/aortic valves was noted at Day 1 in 4 of 5 patients who had a TTE at this stage. No further decline was noted between the first and last post-operative GCBPS (10.8 +/- 3% vs 8.6 +/- 2.1%, p = NS). CONCLUSIONS: A dramatic decrease in native heart EF post-HHTx occurs as early as Day 1 post-transplant. Dissociation of ventricular contraction is the most likely cause. Studies have demonstrated that paced linkage (counterpulsation) between the ventricles results in improved hemodynamics. This may have clinical implications as to the timing of ejection of blood from a left ventricular assist device (LVAD) and for providing the best hemodynamics for the ventricle being assisted and for optimizing its chances of long-term recovery.

Echocardiography↗

PubMed2002

Ten-year experience of endoscopic transanal resection.

OBJECTIVE: To audit the results of endoscopic transanal resection of tumor (ETAR) performed by a single surgeon at a specialized colorectal unit during a 10- year period. SUMMARY BACKGROUND DATA: A minimally invasive surgical technique, ETAR has enabled much progress to be made in the development of local treatment strategies for rectal neoplasia. It can be used in both the curative and palliative management of rectal lesions and is a treatment option for patients who would be unable to tolerate major surgery. METHODS: The surgical outcome of 104 patients (43 women, 61 men) undergoing ETAR under the care of a single surgeon between 1989 and 1999 was reviewed. Patients were identified from the consultant's personal records and cross-referenced with operating room logs. Data were collected retrospectively and no patients were lost to follow-up. RESULTS: One hundred four patients underwent 163 procedures during the study period. Follow-up ranged from 6 months to 10 years. Seventy-five patients with a pre-ETAR diagnosis of benign rectal adenoma underwent resection. In 60 patients, the diagnosis was confirmed to be benign; 30 of these were treated with a single resection and 28 with multiple resections. There were two technical failures, both a result of high mobility of the lesion. In no patients did carcinoma subsequently develop. In the remaining 15 patients the final histology demonstrated a malignancy; 9 patients underwent an open surgical rectal resection and 5 had complete endoscopic resection of their lesion. No carcinomas that were fully resected endoscopically have recurred (follow-up 13 months to 8years). The final patient had an extensive rectal cancer and was palliated for 2 months by ETAR. Twelve patients (8 men, 4 women) underwent ETAR for anastomotic strictures; successful treatment was achieved in 11. The one failure was in a Park's pouch that was subsequently refashioned. Seventeen patients underwent 30 ETARs for palliation of nonresectable rectal adenocarcinoma. Successful palliation of symptoms was achieved in 13 patients and the remainder underwent colostomy formation. One patient died of a myocardial infarction. There were two further complications (blood transfusion for postoperative bleeding, postoperative cerebrovascular accident). CONCLUSIONS: Endoscopic transanal resection of tumor is safe and effective and offers successful palliation or definitive treatment of rectal lesions with low rates of death and complications when performed by a dedicated surgeon.

Adenoma↗

PubMed2002

Effect of mechanically simulated diaphragmatic respiratory motion on myocardial SPECT processed with and without attenuation correction.

UNLABELLED: The goal of this study was to assess the effect of diaphragmatic respiratory motion on inferior wall cold artifact in myocardial SPECT and to assess the ability of attenuation correction (AC) to correct for this artifact in the presence of diaphragmatic motion. METHODS: We used an anthropomorphic phantom with ventricular wall activity, variable ventricular caudal tilt, attenuating liver and spleen cold inserts, and variable vertical (diaphragmatic) motion amplitude and pattern. Cardiac SPECT images were acquired on a gamma camera with dual scanning transmission line sources and commercially available AC software (with scatter correction and iterative reconstruction). The acquired data were processed either using filtered backprojection or with the AC software. The resulting myocardial activity maps were processed with polar plots and with standardized inferior-to-anterior and anterior-to-lateral wall ratios. RESULTS: Subdiaphragmatic attenuation reduces inferior wall counts and this component of inferior wall artifact is fully corrected by AC relative to anterior wall counts both with and without diaphragmatic respiratory motion. In the phantom, diaphragmatic motion artifact manifests as reduction in relative count density in both the anterior wall and the inferior wall relative to the lateral wall, which is not corrected by AC. This artifact becomes more marked with increasing respiratory amplitude and its symmetry depends on the pattern of diaphragmatic motion. CONCLUSION: Images with AC acquired at small respiratory amplitudes (approximately 2 cm) in the phantom resemble images with AC found in published normal patient databases. These results support a clinical need for respiratory gating of myocardial SPECT images.

Adult↗

PubMedDate not supplied

Contributions of subdiaphragmatic activity, attenuation, and diaphragmatic motion to inferior wall artifact in attenuation-corrected Tc-99m myocardial perfusion SPECT.

BACKGROUND: Subdiaphragmatic activity and diaphragmatic motion both contribute to inferior wall artifacts in technetium 99m myocardial perfusion single photon emission computed tomography (SPECT). METHODS AND RESULTS: We used an anthropomorphic phantom with ventricular wall activity, liver/spleen inserts containing variable Tc-99m activity, and variable vertical (diaphragmatic) motion amplitude. SPECT and transmission scans were obtained on a GE Optima NX camera. Data were processed by use of filtered backprojection or attenuation correction (AC). Resulting myocardial activity maps were analyzed with standardized inferior-anterior and anterior-lateral wall ratios. At a subdiaphragmatic-myocardial activity ratio of 0.5:1, inferior wall attenuation predominates, producing a cold artifact. AC corrects inferior wall activity to the level of the anterior wall irrespective of diaphragmatic motion. At a subdiaphragmatic-myocardial activity ratio of 1:1, inferior wall counts vary widely depending on the proximity of subdiaphragmatic activity to the ventricle. With increasing diaphragmatic amplitude, the overlap of subdiaphragmatic activity and inferior wall worsens, leading to a complex mixture of cold and hot artifacts, not corrected by AC. CONCLUSIONS: Concentration and proximity of subdiaphragmatic Tc-99m activity relative to myocardium comprise a major factor in the nature and severity of inferior wall artifacts. If the subdiaphragmatic Tc-99m concentration is equivalent to that in the myocardium, complex, potentially uninterpretable hot and cold inferior wall artifacts are produced.

Artifacts↗