John O. Pastore

Right ventricular infarction: Clinical diagnosis and differentiation from cardiac tamponade and pericardial constriction

Twelve patients with a clinical diagnosis of right ventricular infarction are described. All had acute inferior wall myocardial infarction associated with the bedside findings of jugular venous distension, clear lungs on auscultation, and arterial hypotension. Hemodynamically, there was elevation of right-sided filling pressures not explained by normal or minimally elevated pulmonary wedge pressures. Four patients had an incorrect diagnosis of acute cardiac tamponade. However, a review of the data showed that the hemodynamic features of right ventricular infarction more closely resemble those of pericardial constriction, a point that may be helpful in distinguishing right ventricular infarction from cardiac tamponade. Invasive and noninvasive techniques that exclude the presence of pericardial fluid and suggest enlargement and abnormal contractility of the right ventricle were helpful in establishing the diagnosis of right ventricular infarction in several patients.

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.

In vivo Magnetic Resonance Imaging and Surgical Histopathology of Intracardiac Masses: Distinct Features of Subacute Thrombi

We evaluated intracardiac masses in vivo, in situ and histologically to determine tissue properties revealed by magnetic resonance (MR) imaging. In 15 consecutive patients scheduled for cardiotomy, the cardiac chambers were studied preoperatively with MR imaging and echocardiography. Visual examination of one or more chambers was performed during cardiotomy for mitral valve replacement, aneurysmectomy, atrial septal repair and atriotomy. Six thrombi (1 atrial appendage, 5 ventricular) and 2 atrial myxomas were removed and subjected to histological analysis. All masses were detected preoperatively by MR imaging. The smallest was a subacute 3-mm mural clot in the left ventricle and was undetected by transesophageal and transthoracic echocardiography. The 3 subacute clots had homogeneously low MR signals, did not enhance with gadolinium and exhibited magnetic susceptibility effects; histopathology confirmed these clots to be avascular and laden with dense iron deposition related to hemoglobin breakdown products. The 3 organized clots had intermediate and heterogeneous MR signals and multiple areas of gadolinium enhancement. The 2 myxomas had low MR signals and gadolinium enhancement in the core and septal attachment; these areas had dense neovascular channels. Subacute thrombi appear to have MR features that are distinct from organized thrombi and myxomas, and MR images of subacute thrombi contrast sharply with normal cardiac structures, enabling detection of thin mural clots that may be echographically occult. These findings may be of value, because a subacute clot may be more likely than an organized thrombus to give rise to an embolus.

Intraoperative Multiplane Transesophageal Echocardiography for Guiding Direct Myocardial Gene Transfer of Vascular Endothelial Growth Factor in Patients with Refractory Angina Pectoris

Gene transfer for therapeutic angiogenesis represents a novel treatment for patients with chronic angina refractory to standard medical therapy and not amenable to conventional revascularization. We sought to assess the role of intraoperative multiplane transesophageal echocardiography (MPTEE) in guiding injection of naked DNA encoding vascular endothelial growth factor (VEGF) into the left ventricular (LV) myocardium of patients with refractory angina. After exposing the LV myocardium via a limited lateral thoracotomy, each of 17 patients in this series received 4 separate injections of VEGF DNA into different myocardial sites. Initial injections in the first patient produced intracavitary microbubbles, indicating injection of DNA into the LV chamber. Subsequently, each injection was preceded by a test injection of agitated saline. The absence of microbubbles while visualizing the LV cavity during the test injection verified that the ensuing injection of DNA would not be inadvertently squandered in the LV chamber itself. Intracavitary LV microbubbles were observed by MPTEE in 13 of 64 (20.3%) saline test injections and in 8 of 16 (50.0%) patients in which saline test injection was used, leading to adjustments in needle position. MPTEE imaging detected a previously unknown large, apical left ventricular thrombus in one patient, thereby preventing inadvertent injection of VEGF DNA through the myocardium into the thrombus. Imaging during and after injection verified no deleterious impact on LV function. We conclude that MPTEE is a useful tool for ensuring that myocardial gene therapy performed by direct needle injection results in gene transfer to the LV myocardium.

Differentiation of constrictive pericarditis from restrictive cardiomyopathy by computed tomographic imaging

Differentiation of restrictive cardiomyopathy from constrictive pericarditis is notoriously difficult. Evaluation of such patients by noninvasive means including physical examination, electrocardiography, chest x-ray examination, and echocardiography has been shown to be unreliable.‘e7 Even cardiac catheterization may not be decisive in determining whether impaired diastolic filling is due to a cardiomyopathic process as opposed to thickening of the pericardium,“” and thoracotomy may be required to establish the diagnosis.*“* l3 Recent experience with computed tomographic imaging of the heart suggests that this diagnostic modality provides accurate definition of pericardial thickness.**-lfi We therefore undertook the present study to determine whether computed tomographic imaging of the chest could accurately differentiate patients in whom impaired ventricular diastolic filling was due to constrictive pericarditis from those with a restrictive cardiomyopathy.

Catheter-based intravascular ultrasound discriminates bicuspid from tricuspid valves in adults with calcific aortic stenosis

A catheter-based intravascular ultrasound transducer was used to study aortic valve morphology in adults with calcific aortic stenosis. Examination of 14 postmortem specimens disclosed that intravascular ultrasound consistently identified the number of cusps or the presence of a calcified median raphe in the conjoined cusp, or both, and thereby distinguished a calcified bicuspid from a calcified tricuspid aortic valve. These postmortem findings were then employed to identify valvular morphology in 15 patients undergoing diagnostic cardiac catheterization or balloon aortic valvuloplasty, or both. Reproduction of criteria established in vitro allowed discrimination of congenital valvular morphology in all 15 patients, including 7 in whom assessment by intravascular ultrasound was confirmed by subsequent pathologic examination. Identification of aortic valvular morphology by intravascular ultrasound has potential therapeutic implications for patients considered to be candidates for operative or nonoperative aortic valvuloplasty.

Limitations of color flow doppler imaging in the quantification of valvular regurgitation: Velocity of regurgitant jet, rather than volume, determines size of color doppler image*

The objective of this study was to determine the validity of estimation of regurgitant volume by visual assessment of color flow Doppler display. An experimental apparatus was designed that is capable of ejecting precise volumes of echogenic material from one chamber to another under continuous color flow Doppler monitoring. The velocity of flow was altered independently by changing either the size of the orifice through which flow occurred or the ejection rate. In this manner the differential effects of volume and velocity on the color flow Doppler image could be examined. The maximum area encompassed by the color flow Doppler pattern for each ejection was planimetered by using commercially available on-line software. In addition the reviewer in each case applied a subjective grade to the appearance of the color flow jet (1+ to 4+). Comparison was then made of the color flow Doppler appearance of equal volumes flowing at different velocities and of different volumes flowing at different velocities. In the initial series a solution of agitated hetasarch was used. When equal volumes were imaged at different velocities the higher-velocity jet appeared larger, both subjectively (3+ vs 1+) and by measuring the area encompassed in the Doppler flow profile (40.3 +/- 1.8 vs 22.0 +/- 1.4 cm2, p = 0.0001). Furthermore, when different volumes were imaged at different velocities, the smaller volume (3 ml vs 6 ml) appeared larger when it was flowing at higher velocity (3+ vs 2+, 40.3 +/- 1.8 vs 32.4 +/- 1.3 cm2, p = 0.0006). These experiments were repeated with blood, confirming the results of the initial study.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive assessment of peripheral vascular disease by color flow Doppler/two-dimensional ultrasound

Abstract The development, in 1985, of phased array scanning in a linear format 1 established the potential for acquiring high quality color flow Doppler (CFD) maps of the vasculature in the lower extremities. Subsequently, however, little information has been published 2,3 describing examination of the peripheral arteries by CFD, whether in linear, sector or anular format. Accordingly, the present study was undertaken to evaluate the utility of CFD in combination with 2-dimensional ultrasound (2DU) for the assessment of peripheral vascular disease.

Echocardiographic detection of a retained left atrial catheter

An 18-year-old woman underwent the repair of traumatic lacerations of the mitral valve, tricuspid valve, and interventricular septum. At the time of surgery, an indwelling left atrial catheter was placed for postoperative hemodynamic manangement. An attempt to remove the catheter completely several days following surgery was unsuccessful, but it was initially assumed by the surgeon that the tip of the catheter had been withdrawn from the left atrium. When the patient developed neurologic signs suggesting a cerebral embolism, an echocardiogram was performed. Echo demonstration of the catheter in the left atrium led to repeat thoracotomy for removal of the retained line. Baseline echocardiograms are indicated in cardiac surgical patients with indwelling left atrial catheters and echo study can be diagnostic if catheter retention occurs.

Effect of local lidocaine anesthesia on ventricular escape intervals during permanent pacemaker implantation in patients with complete heart block

Transient asystole is often noted during the course of permanent pacemaker implantation in patients with complete heart block. Since subcutaneous lidocaine is frequently used as the local anesthetic agent for permanent pacemaker implantation, the effect of this drug on ventricular escape intervals was studied. Ventricular escape intervals after transient cessation of pacing were studied in 9 patients with complete heart block before and 10, 30, and 45 minutes after subcutaneous lidocaine administration for permanent pacemaker implantation. The total lidocaine dose ranged from 170 to 400 mg (1.9 to 9.5 mg/kg of body weight). Therapeutic blood levels were achieved in 7 patients. The mean ventricular escape interval before lidocaine was 1.83 +/- 0.32 seconds, which increased to 2.58 +/- 1.35, 2.96 +/- 1.06, and 2.68 +/- 1.27 seconds at 10, 30, and 45 minutes after lidocaine (p less than 0.02). The mean maximal escape interval before lidocaine was 2.06 +/- 0.30 seconds, which increased to 3.80 +/- 1.44 seconds (p less than 0.01), a mean increase of 84%. The percent increase in maximal escape interval was related directly to the peak lidocaine level achieved. After lidocaine administration, 5 patients had asystole greater than 4 seconds and 1 required resumption of pacing. Thus, subcutaneous lidocaine contributes to the occurrence of asystole seen during permanent pacemaker implantation. It is advisable to limit the amount of lidocaine administered during permanent pacemaker implantation to the minimum necessary to achieve adequate local anesthesia. Strong consideration should be given to the use of a temporary pacemaker in patients with complete heart block during permanent pacemaker implantation even in the absence of previous asystole.