Biomedical subjects

J M Isner

Publications and source records attributed to J M Isner.

347 records · Page 20Linked to original sources

PubMedDate not supplied

The relation of clinical outcome to dissection and thrombus formation during coronary angioplasty. Heparin Registry Investigators.

BACKGROUND: Although the development of thrombus or dissection during percutaneous transluminal coronary angioplasty (PTCA) increases the risk of abrupt vessel closure, the magnitude of the effect is difficult to define. OBJECTIVE: The aim of the study was to determine prospectively the effect of the development of thrombus or dissection on PTCA procedural outcome. METHODS: Data from 591 consecutive angioplasty procedures involving 756 lesions at 9 clinical centers were included in a prospective registry with a core angiographic laboratory. RESULTS: Clinical success (defined as < 50% stenosis of all target lesions assessed in a core angiographic laboratory, with no major complications of death, Q wave or non-Q wave myocardial infarction or emergency CABG) was achieved in 497 patients (84%). Major complications occurred in 45 (7.6%). Abrupt vessel closure, including both established closure (TIMI grade 0 or I flow) and impending closure (> 50% stenosis, TIMI grade 0-2 flow, plus use of additional interventions) occurred in 65 patients (11%). Angiographically visible dissections developed in 40% of lesions; more severe grades of dissection were associated with reduced success rates, and increased incidence of and abrupt vessel closure and major complication. Angiographic evidence of thrombus (filling defects) developed in 12.3% of lesions; the presence of thrombus was associated with significantly lower procedural success (61% vs. 86%) and significantly higher rates of abrupt vessel closure (28% vs 7%) and major complications (24% vs. 6%). With multivariable analysis, thrombus was identified as an independent predictor of procedural success, abrupt vessel closure, and major complications. CONCLUSIONS: The development of severe dissections or thrombus following PTCA is associated with significantly lower procedural success rates and higher rates of abrupt vessel closure and major complications. Patients who develop severe dissection or thrombus may be appropriate candidates for more aggressive forms of therapy.

Adult↗

PubMedDate not supplied

Gene therapy to prevent restenosis, the Boston experience.

The delivery of genetic material to the vessel wall is being explored as a means to treat disorders of the vasculature. Gene therapy offers the possibility to directly or indirectly influence the molecular pathways that are disregulated. With regard to postangioplasty restenosis, gene therapy is most often aimed at inhibition of vascular smooth muscle cell (VSMC) proliferation. Here, we review the results of studies in our laboratories that have investigated a number of different strategies to inhibit proliferative vessel wall lesions. These strategies include the administration of genes that block cell cycle progression, induce apoptosis, or promote the growth of vascular endothelium.

Adenoviridae↗

PubMedDate not supplied

Magnetic resonance imaging in ischemic injury after heart transplantation in rats.

Magnetic resonance imaging with and without gadolinium (Gd)-DTPA has been shown to enable detection of coronary occlusive ischemic injury and heart transplant rejection. This study was performed to examine findings on magnetic resonance images associated with ischemic injury after heart transplantation in rats. Magnetic resonance imaging was performed immediately before death in 22 rats, between 1 and 90 days after isogeneic (Lewis grafts, Lewis host; or Fischer graft, Fischer host) heterotopic heart transplantation. Ischemic injury, characterized histologically by cellular infiltration or myocyte necrosis, correlated inversely with graft duration. It was graded as moderate to severe in 5 of 5 rats killed at 1 to 2 days, and in 0 of 9 animals killed at greater than or equal to 30 days. T2-weighted myocardial signal intensity (TR = 2.3 seconds; TE = 90 milliseconds) correlated inversely with graft duration and was significantly greater in grafts with moderate or severe histologic abnormalities than in grafts with absent or minimal changes. GD-DTPA-induced myocardial enhancement was judged on T1-weighted images (TR = 0.5 seconds, TE = 25 milliseconds). Areas of intense enhancement were present in all seven grafts with severe histologic abnormalities, but in only 3 of 15 grafts with absent to moderate histologic abnormalities. In conclusion, after heart transplantation in rats, ischemic injury causes increased T2-weighted signal intensity and Gd-DTPA-induced T1-weighted signal enhancement--findings similar to those described in transient coronary occlusive ischemia and in graft rejection. Abnormalities seen on magnetic resonance images during the first few posttransplant weeks may represent ischemic injury rather than rejection.

Animals↗

PubMedDate not supplied

Heterotopic heart transplantation: electrophysiologic changes during acute rejection.

To identify electrophysiologic (EP) measurements sensitive to heart transplant rejection, heterotopic thoracic heart transplantation was performed in 11 dogs. Endocardial biopsies were performed daily for up to 9 days, and the severity of rejection was classified as mild, moderate, or severe. Late diastolic thresholds; refractory periods of the left ventricle and right atrium; and conduction times from the right atrium to left atrium, left ventricle to right ventricle, and right atrium to right ventricle were measured daily in transplanted and recipient hearts. The amplitude of the left atrium and right ventricular electrograms was recorded daily. In the recipient hearts no significant EP changes were observed after the second postoperative day. Left ventricular and right atrial refractory periods in both hearts did not change. In the transplanted hearts the conduction times of the right and left atria (but not the conduction time of the left to right ventricles) and right atrium to right ventricle identified moderate rejection; right atrial diastolic threshold was a marker only for severe rejection. Amplitudes of the left atrial and right ventricular electrograms decrease significantly only with severe rejection. At postmortem histologic evidence for rejection was greater in the atria than the ventricles. EP changes in the atria and atrioventricular conduction are more sensitive indicators of acute rejection than ventricular EP changes and correlate with the histologic grade of rejection. None of the measurements evaluated, however, was shown to be a sensitive marker of mild rejection.

Acute Disease↗

PubMedDate not supplied

Directional coronary atherectomy in heart transplant recipients.

Cardiac allograft vasculopathy is one of the most common obstacles to the long-term survival of heart transplant recipients. Percutaneous transluminal angioplasty has been used as a palliative treatment for discrete lesions caused by this disease, but it is often complicated by restenosis. This report describes two cases in which directional coronary atherectomy was used to treat the discrete lesions and explores the possible advantages of this intervention in lieu of the traditional approach. Our results suggest that directional coronary atherectomy is a feasible alternative to conventional balloon angioplasty.

Atherectomy, Coronary↗