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Biomedical subjects

R Abben

Publications and source records attributed to R Abben.

9 recordsLinked to original sources
PubMed1990

Recent developments in coronary atherectomy.

Percutaneous coronary atherectomy (PCA) is one of the newest treatments for coronary artery disease. In this technique, arterial plaque is mechanically removed from the interior of the artery by a tool located on the tip of a catheter placed inside the coronary artery nonsurgically. Clinical studies of several coronary atherectomy devices are in process in the United States and abroad. As atherosclerotic material is removed or debulked, abrupt reclosure or restenosis rates may potentially be lower compared with conventional percutaneous transluminal coronary angioplasty (PTCA). PCA may also clear longer and more diffuse lesions, with long-term clinical success, than are successfully being treated by PTCA. Due to the rigidity of the atherectomy catheter, only lesions in major coronary arteries may be approached with these devices at present. It is hoped that PCA may supplement current methods of treating coronary artery disease, including coronary artery bypass graft surgery and PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1990

Functional cardiac imaging in coronary disease: increased sensitivity of first-pass radionuclide angiography utilizing sequential regional left ventricular early diastolic filling rate images.

In 127 patients, 113 with greater than or equal to 50% coronary artery stenosis (CAD), 14 with normal coronaries, cardiac catheterization and first-pass radionuclide angiography (RNA) utilizing left ventricular (LV) regional ejection fraction, first half systolic LV regional mean transit time and ejection rate images were performed. Additionally, the incremental value of a new technique, sequential regional LV filling rate images focusing on the first third of diastole, was established. Diastolic imaging improved RNA sensitivity from 88% (100/113) to 96% (109/113). Single vessel disease sensitivity increased from 77% (23/30) to 90% (27/30), whereas multivessel disease RNA positivity changed from 93% (77/83) to 99% (82/83). LAD system (LAD/D) sensitivity improved by 24% to 94% (79/84); RCA system (RCA/PDA) sensitivity increased 17% to 84% (59/70); circumflex system (CFX/OM) sensitivity was 83% (67/81), an improvement of 5%. Specificity was well maintained despite the increased sensitivity, as 86% (12/14) of patients with normal coronaries were normal by RNA. Furthermore, in the 113 CAD patients, 81% (84/104) of the vessels with insignificant or no stenosis were normal by RNA. We conclude sequential regional LV diastolic filling images substantially increase RNA sensitivity for CAD, while specificity is satisfactorily maintained.

Coronary Disease↗
PubMed1985

Usefulness of transstenotic coronary pressure gradient measurements during diagnostic catheterization.

A difficult problem in coronary arteriography is the assessment of the hemodynamic significance of stenoses that appear angiographically to be of only moderate severity (25 to 75% diameter narrowing). This is particularly important in patients who may be candidates for invasive therapy, such as percutaneous transluminal coronary angioplasty (PTCA) or coronary bypass surgery. To determine the significance of such lesions, we measured transstenotic coronary pressure gradients in 15 patients with angiographically moderate stenoses. For comparison, similar measurements were made in 17 patients with severe stenoses (more than 75% diameter narrowing) being considered for PTCA. The transstenotic pressure gradients were measured with a 2.0Fr polyvinyl chloride catheter cleared of microbubbles of air by flushing with carbon dioxide and degassed saline solution and attached to a low-volume displacement transducer for optimal frequency response. Mean transstenotic pressure gradients greater than 10 mm Hg at rest or more than 20 mm Hg under conditions of high coronary blood flow, as induced by Renografin 76, appeared to be associated with objective evidence of myocardial ischemia and symptomatic relief from PTCA. Smaller pressure gradients occurred in patients whose symptoms probably were not ischemic in nature. Transstenotic pressure gradient determination performed at the time of diagnostic catheterization may provide assistance in clinical decision-making in selected patients with angiographically moderate stenoses.

Angioplasty, Balloon↗
PubMed1985

Percutaneous transluminal coronary angioplasty with an over-the-wire system.

The original Gruentzig coaxial catheter system for percutaneous transluminal coronary angioplasty (PTCA) utilized a blunt, closed-end, inner balloon catheter with a short guide wire attached to its tip. Options for safely crossing severe stenoses with this large, nonmaneuverable catheter were limited. More recently, over-the-wire systems have been developed in which the lesion initially is crossed with a small-caliber floppy or steerable guide wire, then by the balloon catheter advanced over the wire. Technical success was achieved in 78 of our first 100 PTCAs with this system. Significant cardiac complications occurred in ten patients, seven of whom required emergency coronary bypass surgery. A recently published survey of all PTCA techniques reported a technical success rate of 62%. Our higher success rate may be attributed to certain advantages of the over-the-wire system, which are discussed in detail. A learning curve is associated with this procedure: our success rate was 65% in the first 20 cases but 81% thereafter. These results can be considered typical of those expected at hospitals now beginning PTCA programs with advanced over-the-wire technology.

Angioplasty, Balloon↗
PubMed1979

Evaluation of criteria for diagnosis of myocardial infarction: study of 256 patients with intermittent left bundle branch block.

In an attempt to elucidate the specificity and sensitivity of atypical findings during left bundle branch block (LBBB) with respect to myocardial infarction (MI), we analyzed ECGs from patients with intermittent LBBB obtained by mail solicitation of cardiologists. The group consisted of 256 patient files fulfilling the following criteria: 1) complete LBBB present on one or more 12-lead ECGs, and 2) at leat one 12-lead ECG taken subsequent to a LBBB tracing exhibiting absence of LBBB (non-LBBB). The sensitivity of atypical LBBB for predicting presence of MI was 0.41, the specificity 0.64, and the accuracy 0.59. No specific atypical finding was significantly better than any other in predicting MI. We conclude that atypical findings present during LBBB are of little value in predicting the presence of MI (as diagnosed by significant Q waves present during non-LBBB conduction).

Bundle-Branch Block↗