Bernard D. Kosowsky

Acetylcysteine to prevent angiography-related renal tissue injury (the APART trial)

NAC reduces the risk of postcardiac catheterization nephropathy in patients with chronic renal insufficiency and decreased ejection fraction. Thus, it should be considered as routine prophylaxis in patients with chronic renal insufficiency undergoing cardiac catheterization.

Three-dimensional reconstruction of human coronary and peripheral arteries from images recorded during two-dimensional intravascular ultrasound examination

Background Intravascular ultrasound provides high-resolution images of vascular lumen, plaque, and subjacent structures in the vessel wall; current instrumentation, however, limits the operator to viewing a single, tomographic, two-dimensional image at any one time. Comparative analysis of serial two-dimensional images requires repeated review of the video playback recorded during the two-dimensional examination, followed by a “minds eye” type of imagined reconstruction. Methods and Results Computer-based, automated three-dimensional reconstruction was used to generate a tangible format with which to assess and compare a “stacked” series of two-dimensional images. Three-dimensional representations were prepared from sequential images obtained during intravascular ultrasound examination in 52 patients, 50 of whom were studied before and/or after percutaneous revascularization. Conventional two-dimensional ultrasound images were acquired by means of a systematic, timed pullback of the ultrasound catheter through the respective vascular segments. Images were then assembled in automated fashion to create a three-dimensional depiction of the vessel lumen and wall. Computer-enhanced three-dimensional reconstructions were generated in both sagittal and cylindrical formats. The sagittal format resulted in a longitudinal profile similar to that obtained during angiographic examination; in contrast to angiography, however, the. sagittal reconstruction offered 360° of limitless orthogonal views of the plaque and arterial wall as well as the vascular lumen. The cylindrical format yielded a composite view of a given vascular segment, and a hemisected version of the cylindrical reconstruction enabled en face inspection of the reconstructed luminal surface. Sagittal reconstructions facilitated analysis of dissections and plaque fractures resulting from percutaneous revascularization, and the hemisected cylindrical reconstructions enhanced analysis of endovascular prostheses. Conclusions This preliminary experience demonstrates that computer-based three-dimen-sional reconstruction may further augment the use of intravascular ultrasound in assessing vascular pathology and guiding interventional therapy.

Long-Term Use of Procaine Amide following Acute Myocardial Infarction

The safety of long-term prophylactic antiarrhythmic therapy with procaine amide was studied in 78 patients recovering from acute myocardial infarction. Patients were randomly allocated to a control or treatment group and followed monthly for up to 2 years with ambulatory ECG monitoring and measurement of serum drug level, antinuclear antibody (ANA) titer, LE preparation, blood count, BUN, and SGOT. Early reactions forced discontinuation of therapy in nine of 39 treated patients within the first 3 weeks. Late reactions were observed in 14 of 16 patients who took procaine amide for 3 months or longer. Every patient on therapy for 1 year or longer demonstrated elevation in ANA titer. Comparison of monitoring data between these two groups revealed no difference in the incidence of occasional or frequent premature ventricular beats. However, during the first 6 months, treated patients tended to have fewer major arrhythmias. There were fewer sudden deaths among treated patients, but this difference did not reach statistical significance at the 5% level. It is concluded that the high incidence of toxic reactions precludes widespread use of long-term prophylactic procaine amide therapy. More precise identification of a sudden death-prone population might justify such therapy in such selected cases.

Combination balloon-ultrasound imaging catheter for percutaneous transluminal angioplasty. Validation of imaging, analysis of recoil, and identification of plaque fracture.

BackgroundWe investigated the hypothesis that an ultrasound transducer positioned within an angioplasty balloon could be used to perform quantitative assessment of arterial dimensions before and after percutaneous transluminal angioplasty (PTA) and to identify certain mechanical alterations consequent to PTA, including vascular wall recoil and the initiation of plaquefractures. Methods and ResultsA combination balloon-ultrasound imaging catheter (BUIC) that houses a 20-MHz ultrasound transducer within and halfway between the proximal and distal ends of an angioplasty balloon was used to perform PTA in 10 patients with peripheral vascular disease. Each PTA site was also evaluated before and after PTA by standard (nonballoon) intravascular ultrasound (IVUS) technique. In eight patients in whom satisfactory images were recorded with the BUIC before PTA, luminal cross-sectional area (XSA) of stenotic sites (0.10 ± 0.01 cm2) did not differ significantly from measurements of XSA by IVUS (0.09 ± 0.01 cm2, p=NS). Likewise, minimum luminal diameter (Dmin) measured by BUIC (0.34 ± 0.02 cm) was similar to that measured by IVUS (0.33 ± 0.01 cm, p=NS). In nine patients in whom satisfactory images were recorded with the BUIC after PTA, XSA measured by BUIC (0.29 ± 0.03 cm2) did not differ significantly from XSA measured by IVUS (0.30 ± 0.03 cm2, p=NS). Dmin measured by BUIC after PTA (0.57 ± 0.02 cm) was also similar to D.,. measured by IVUS (0.57 ± 0.03 cm, p=NS). After PTA, XSA and Dmin measured immediately after deflation were significantly less than balloon XSA and diameter at full inflation, indicating significant elastic recoil of the dilated site. For the nine patients in whom post-PTA images were satisfactory for quantitative analysis, including four patients in whom recoil was 39%o, 46%, 50%, and 61%, percent recoil measured 28.6 ± 7.2%. Finally, plaque fractures were identified on-line in six of 10 patients (60%); in each case, initiation of plaque fracture was observed at inflation pressures of 2 atm or less. Conclsions. The results of this preliminary human investigation indicate that an ultrasound transducer positioned within an angioplasty balloon can be used to perform quantitative and qualitative analyses of lumen-plaque-wall alterations immediately preceding, during, and immediately after PTA in patients with peripheral vascular disease.

Atrioventricular conduction in man: Effect of rate, exercise, isoproterenol and atropine on the P-R interval☆

Abstract Atrioventricular conduction was studied in 14 patients. A bipolar electrode catheter was placed in the right atrium, and the heart rate was controlled by atrial pacing. Increases in the sinus heart rate were associated with decreases in atrioventricular conduction time. When the heart rate was increased by atrial pacing, there were progressive increases in atrioventricular conduction time. Exercise, isoproterenol and atropine shortened atrioventricular conduction time. In those cases where atrioventricular conduction block occurred during atrial pacing, there was a 1:1 atrioventricular response during exercise at the same paced heart rate. Stimuli which increase the rate of discharge of the sinus pacemaker also enhance atrioventricular conduction. It is concluded that there is a fine balance between heart rate and A-V conduction. When the heart rate is increased by neurohumoral stimuli, there is a corresponding enhancement of A-V conduction. When the heart rate is increased by artificial stimulation of the atria and neurohumoral effects are not altered, there is a progressive increase in conduction time and eventual blockage of conduction at the A-V nodal region.

Termination of atrial flutter by rapid electrical pacing of the atrium

Abstract A technic has been developed for converting atrial flutter to normal sinus rhythm utilizing an intra-atrial electrode catheter and rapid impulses 10 milliamperes in magnitude delivered directly to the atrial wall. Atrial flutter has been converted to normal sinus rhythm in 3 patients after premedication with small doses of quinidine or procainamide. No anesthesia is required, the ventricle is at no time depolarized by the shock, and there is no ventricular irritability produced.

Re-evaluation of the atrial contribution to ventricular function: Study using His bundle pacing☆

The atrial contribution to ventricular function was studied in the presence of normal and abnormal ventricular depolarization in 8 dogs. The use of His bundle pacing made it possible to pace the ventricles and yet maintain a normal pattern of ventricular activation. Ventricular function, measured by peak left ventricular pressure, left ventricular dp/dt and aortic flow, was significantly decreased in the presence of a very short P-R interval with both right ventricular and His bundle pacing. Under both circumstances ventricular function improved as the P-R interval approached normal. However, the variations in function were more pronounced with aberrant ventricular depolarization. At any P-R interval ventricular function was better in the presence of normal ventricular depolarization than with right ventricular pacing. The improvement was more pronounced at short than at near normal P-R intervals, even in the presence of compensatory phenomena. It is apparent that the temporal relation between atrial and ventricular contraction and the pathway of ventricular depolarization are both important determinants of ventricular function. The role of either factor is accentuated when the contribution of the other is least effective. Certain clinical implications of these findings are suggested.

Results and complications of intraaortic balloon pumping in surgical and medical patients.

The intraaortic balloon was attempted for therapy in 94 patients and successfully placed in 86. The balloon catheter could not be passed through the femoral or iliac artery in 12 patients (13 percent) of the group; in 4 of these the balloon was inserted through an aortic arch graft. The medical indications were cardiogenic shock and preinfarction angina. Ten of the 14 patients in the group with shock survived when treated with an aortic balloon without emergency surgery. Indications for balloon pumping in the surgical group included inability to wean the patient from the pump-oxygenator, postoperative shock and prophylactic placement of the balloon for poor ventricular function. Inability to remove a patient from pump-oxygenator support was the most common surgical indication, and 47 percent of patients were long-term survivors. Only 1 of the 17 patients for whom balloon pumping was used prophylactically died. Complications occurred in 17 percent of the entire group of 86 patients although the rate for medical patients with cardiogenic shock was 50 percent. The most common complication was arterial insufficiency requiring removal of the balloon. Four patients had permanent damage to the legs from ischemia, one patient requiring bilateral amputation. The overall incidence of serious arterial obstruction was 10 percent. Other complications included balloon displacement with arterial obstruction and pericardial tamponade from anticoagulant agents resulting in death.

The Relation of Heart Rate to Cardiovascular Dynamics Pacing by Atrial Electrodes

Hemodynamic studies were carried out as heart rates were controlled by atrial pacing on 10 normal patients at rest and during exercise. Each patient served as his own control. In both states tested the cardiac index, left ventricular work, and peripheral resistance were not significantly altered by changes in heart rate. The stroke index and mean systolic ejection rate decreased linearly with heart rate. During exercise the cardiac index increased up to 98% and again remained constant at all paced heart rates tested. At comparable heart rates the tension-time index, left ventricular work, stroke index, and mean systolic ejection rate were higher during exercise than at rest. At comparable heart rates[see figure in the PDF file]peripheral resistance was 38% lower during exercise than at rest. Myocardial oxygen consumption, as inferred from the tension-time index, increased with heart rate in both states.

Atrial Fibrillation Produced by Atrial Stimulation

Twenty-six episodes of atrial fibrillation and flutter-fibrillation, each lasting less than 23 sec, were recorded in three normal subjects during atrial pacing studies. The cause of these atrial arrhythmias was determined to be the result of stimulation within the atrial vulnerable period.