Biomedical subjects

M M Cayton

Publications and source records attributed to M M Cayton.

8 recordsLinked to original sources

PubMed1997

Transmyocardial laser revascularization: historical background and future directions.

Transmyocardial laser revascularization (TMLR) was investigated as a possible treatment alternative for patients with refractory coronary artery disease. This paper is a summary of nearly four decades of research by the authors. Beginning in 1969 experimental studies were conducted on the beating heart. A prototype 450 W carbon dioxide laser was used to create channels in the ischemic myocardium. Initial clinical studies began in 1984. A protocol was developed for TMLR as an adjunct to CABG in those patient who had at least one vessel which could be bypassed and areas of ischemia which were not amenable to bypass. In the early 1990's the development of a 850 W CO2 laser for clinical use allowed us to begin investigation of TMLR on the beating heart. Patients with end stage coronary artery disease who were not candidates for other forms of treatment were selected. The early results are encouraging with patient followup of from 3 months to 5 years. There are numerous controversies regarding the effects of TMLR on myocardial function and perfusion. To quantify these effects the authors have performed acute and chronic studies on swine using sophisticated techniques with 3D cine magnetic resonance imaging. We concluded TMLR improved left ventricular function and perfusion in acute and chronic ischemia.

Animals↗

PubMed1993

Transmyocardial laser revascularization: a review.

There is an increasing number of treatment alternatives available for those with ischemic heart disease. Surgical procedures are more sophisticated, a wide array of medications are available, and numerous catheter techniques have evolved to treat patients with coronary artery disease. Technical advances and lifestyle modifications have contributed to a decline in age-adjusted death rates. Despite these advances, there remain a significant number of patients with myocardial ischemia who are not candidates for conventional therapies. Transmyocardial laser revascularization may be a viable adjunct or alternative therapy. In performing this technique, channels are made, from the epicardial surface of the heart through the left ventricle and endocardium, with the CO 2 laser. Perfusion is from the blood supply in the left ventricle via the channels. Postoperative thallium stress tests and left ventriculography indicate that the channels remain patent and protect the ischemic muscle. Experimental and early clinical results of transmyocardial laser revascularization suggest that a group of patients may benefit from this treatment.

Follow-Up Studies↗

PubMed1990

Evaluation of clinical results following laser recanalization of the peripheral arteries.

As experience is gained with laser-assisted angioplasty and as long-term follow-up results become available, a realistic and objective view of its role in the treatment of patients with occlusive disease of arteries in the peripheral vascular tree is becoming available. Comparison with results of conventional treatment methods is warranted. Experience in treating patients with vascular lesions is helpful in patient selection, management during the procedure, and follow-up care. Evaluation of experience in 169 procedures, with a follow-up time of 1 month to 3 years indicates what direction evolving patency rates are taking.

Adult↗

PubMed1988

New concepts in revascularization of the myocardium.

The concept of direct revascularization of ischemic myocardium by transmural left ventricular conduits has been investigated by several researchers. Early success was followed by closure of the pathways by fibrosis and scarring caused by mechanical trauma. The CO2 laser was examined as an alternative method of creating channels. Early experiments supported the hypothesis that laser channels would perfuse ischemic areas and would remain patent. Histological examination showed patent, endothelialized channels more than 2 years following operation in the experimental model. A clinical protocol was designed to assess the results of laser revascularization in a series of 12 patients. Patients selected were candidates for bypass grafting, but because of the coronary artery pathology involved, it was thought bypass grafting alone would result in incomplete revascularization. None of the 12 patients have died. Follow-up ranges from 3 to 32 months. Postoperative thallium stress tests and left ventriculography indicate that channels have remained patent and that they perfuse the myocardium. Direct laser revascularization of the myocardium may offer a viable adjunct in the treatment of ischemic heart disease.

Adult↗

PubMed1986

Laser myocardial revascularization.

A significant number of patients with ischemic heart disease are not candidates for coronary artery bypass or percutaneous transluminal angioplasty and do not respond to medical management. This group includes those who have diffuse coronary artery disease, those with poor ventricular function, and those who have had poor results from previous surgery. Developing a method to directly revascularize the myocardium by creating channels through the ventricular wall has challenged many investigators. Early methods, including needle acupuncture, were successful in the acute phase, but long-term patency could not be achieved. Closure of the channels was due to fibrosis and scarring. Experiments in our laboratory demonstrated that myocardial channels, made with the CO2 laser, remained patent up to five years. Histopathologic examination of the channels showed minimal damage to the surrounding cells in the acute phase. Studies at intervals of two months to two years showed patent endothelialized channels, with no evidence of fibrosis. Channels created in the myocardium protected the ventricle against an ischemic event when the left anterior descending branch of the coronary artery was ligated. Clinical experience with direct myocardial revascularization by CO2 laser indicates it may be a viable method of treating those patients with ischemic heart disease who are not candidates for other forms of management. The treatment and early postoperative follow-up in one patient are described.

Aged↗

PubMed1982

Transventricular revascularization by laser.

Transventricular acupuncture or revascularization by the method of producing channels between the ventricular cavity and the ischemic myocardium has challenged several investigators. The concept of producing these channels using high-energy CO2 laser was based on the finding that the laser beam could produce small channels devoid of debris, and fibrosis would not occur. Four groups of mongrel dogs with six animals in each group were studied. In three groups the left anterior descending (LAD) branch of the coronary arteries was ligated above the first diagonal, and channels were made in the myocardium according to the protocol for each group. The fourth group was the control, the LAD was ligated but the myocardium was not exposed to laser treatment. In the control group all animals died within 20 minutes of LAD ligation. Animals in the other groups survived ligation with laser, and were subsequently sacrificed at varying intervals. At autopsy the epicardial component of the channels was visible. Penetration through the myocardium could be demonstrated. Microscopically the channels were patent and endothelialized. Further investigations are in process, but we believe laser channels protect and nourish the ischemic myocardium.

Animals↗

PubMed1981

Revascularization of the heart by laser.

The possibility of revascularizing the myocardium with high-energy laser was investigated based on the finding that the laser beam could produce small channels in the tissue of the myocardium that were devoid of debris and scarring. The technique was investigated in 4 groups of 6 mongrel dogs each. In 3 of the groups, the left anterior descending (LAD) coronary artery was ligated above the first diagonal branch and the myocardium was treated with the laser energy according to the protocol of that group. In the fourth control group, the LAD artery was ligated but the myocardium was not subjected to laser treatment. In the first 3 groups, the myocardium was protected by the channels produced by the application of the laser energy. The animals were subsequently sacrificed at various intervals. In the control group, all of the animals died within 20 minutes of ligation of the artery. At autopsy, the epicardial sites of the channels created by the laser were clearly visible and a lack of charring in the channels was demonstrated. The penetration through the endocardial surface could be demonstrated. Microscopically, the channels were patent and endothelialized. It is concluded that the channels created in the myocardium effectively helped to protect the myocardium from acute coronary artery occlusion in this model in dogs.

Animals↗

PubMedDate not supplied

Nursing responsibilities in laser surgery.

The increasing use of lasers in surgery requires a knowledgeable surgical team. An essential member of this team is the nurse, who has specific responsibilities to ensure safety during laser use. In addition, the nurse must serve as the liaison between the medical staff, hospital administration, patient, and other personnel. Such a role requires that the nurse have an understanding of lasers, their clinical applications and surgical techniques, and most specifically their safe use.

Eye Protective Devices↗