Means for load variation during echocardiographic assessment of the Frank-Starling relationship.

Because minimally invasive methods of preload variation are not validated for load-insensitive indexes of cardiac performance, intravenous nitroglycerin (NTG), phenylephrine, and saline solution (VOL) boluses were used in blocked and intact autonomic states to alter load and were compared with vena caval occlusion in the assessment of preload recruitable stroke work relationships between stroke work and left ventricular end-diastolic volume in dogs. In both autonomic states NTG and VOL produced comparable linear relationships. NTG and saline solution were combined with noninvasive measurements of left ventricular pressure and volume to construct echocardiographic relationships between stroke work and left ventricular end-diastolic cross-sectional area; NTG produced linear relationships similar to vena caval occlusion. Therefore NTG and VOL reliably alter load in constructing preload recruitable stroke work relationships, and NTG may be used with noninvasive measurements to provide load-insensitive estimates of cardiac function in a minimally invasive manner.

Assessment of the Frank-Starling relationship by two-dimensional echocardiography.

The Frank-Starling relationship between left ventricular stroke work and end-diastolic minor-axis cross-sectional area was evaluated as a load-insensitive measure of inotropic state by two-dimensional echocardiography in 10 conscious dogs. Stroke work was calculated as the product of systolic change in cross-sectional area and either (1) beat-to-beat mean arterial pressure or (2) initial systolic blood pressure. Both Frank-Starling relationships were highly linear during preload variation (mean r = 0.96), sensitive to the inotropic state (slope increase with calcium 51% +/- 43% and 62% +/- 53%, respectively), and insensitive to afterload (r < 0.4, slope or x intercept versus afterload). Thus the Frank-Starling relationships derived from two-dimensional echocardiographic images and peripheral arterial pressure may be a useful and practical means of assessing inotropic state with minimally invasive measurements.

Intraoperative echocardiography during congenital heart operations: experience from 1,000 cases.

BACKGROUND: This article provides an overview of the application of intraoperative echocardiography during repair of congenital heart defects based on our experience with 1,000 patients. METHODS: The patients in this study all underwent repair of a congenital heart defect between 1987 and 1994 at Duke University Medical Center. Echocardiography was performed on all patients in the operating room both before and after repair using epicardial or transesophageal imaging (or both). Hospital costs and outcome data were obtained for all patients. RESULTS: Overall, 44 patients (4.4%) underwent intraoperative revision of their repair based on echocardiographic findings. There was an initial learning phase during which 8.5% of repairs needed to be revised. With experience, the number of revisions fell to as low as 3% to 4%, but need for revision continued to occur throughout the series. Thirty-nine patients (88.6%) had a successful revision. It was not possible for the surgeon to predict the need for a revision based on his confidence in the repair: in 2.6% of patients thought by the surgeon to have a good repair, intraoperative echocardiography revealed the need for operative revision. The average cost for patients who return to the operating room during their hospitalization for revision of a repair is significantly greater than for those whose repairs are revised before they leave the operating room ($94,180.28 +/- $33,881.63 versus $21,415.79 +/- $8,215.74). There were no significant complication attributable to intraoperative echocardiography. CONCLUSIONS: In an era where complete repair of congenital heart defects is emphasized, intraoperative echocardiography provides information that can guide successful operative revision so that babies leave the operating room with optimal results.

Does hypotension during dobutamine stress echocardiography correlate with anatomic or functional cardiac impairment?

The development of hypotension during various exercise stress tests has been correlated with the presence of multivessel coronary artery disease and impaired left ventricular contractility. Hypotension may also occur during dobutamine stress echocardiography; however, its anatomic and functional significance remains unknown. As part of an ongoing study of restenosis, dobutamine stress echocardiography and diagnostic cardiac catheterization were performed on the same day in 105 outpatients approximately 6 months after percutaneous coronary revascularization (balloon angioplasty or directional coronary atherectomy) to determine the anatomic and functional significance of dobutamine-induced hypotension. Dobutamine was infused in stepwise increments to a maximum rate of 30 micrograms/kg/min. Hypotension was defined as a reduction in systolic blood pressure of > or = 15 mm Hg. Anatomic abnormalities were defined by quantitative coronary angiography and functional abnormalities by digitized two-dimensional stress echocardiography. Clinical, angiographic, hemodynamic, and electrocardiographic data underwent multivariable regression analysis to determine their ability to predict independently the development of dobutamine-induced hypotension. Dobutamine-induced hypotension was not associated with the presence of severity of coronary artery disease or with echocardiographic wall motion abnormalities. Univariable predictors of stress-induced hypotension included high baseline systolic blood pressure, advanced age, and high left ventricular ejection fraction. Only a high baseline systolic blood pressure contributed independent predictive information in multivariable stepwise logistic regression analysis. Therefore, the development of hypotension during dobutamine stress echocardiography, unlike that during traditional exercise stress tests, is not associated with the presence of significant coronary artery disease or left ventricular dysfunction.

Improved cardiac anthropomorphic phantom.

An improved cardiac sonographic phantom is described that simulates the anatomy of the human heart for applications as a low cost quality assurance and training tool in echocardiography. The major new feature in the phantom is the development of a polyurethane sponge left ventricle, which mimics the myocardium during sonographic imaging while undergoing hydraulic pumping. The left ventricle, including prosthetic mechanical mitral and aortic valves, is housed in an optically transparent Lexan chamber or in a tissue mimicking polyurethane rubber torso. Additional new features include a port for transesophageal imaging, and an adjustable calibrated stroke volume on the piston pump, which can serve as a standard for echocardiographic stroke volume measurement. B-scans of the phantom show excellent image quality in all three standard echocardiographic views as well as in transesophageal scanning.

Measurement of left ventricular volume in normal and volume-overloaded canine hearts.

Serial studies of adaptation to aortic regurgitation (AR) were undertaken to determine whether sonomicrometry and echocardiography could be combined to measure changes in left ventricular (LV) cavitary volume (Vlv) and wall mass using the geometric formula [Vlv = K pi b2 alpha--wall volume], where K is a constant depending on the geometric model and a and be are epicardial major- and minor-axis diameters, respectively. Postmortem studies were performed in six normal dogs and in nine with AR; ultrasonic ventricular dimensions were measured as Vlv was varied with an intracavitary balloon. Three models were tested: 1) ellipsoid (model I; K = 1/6), 2) cylinder-ellipsoid (model II; K = 5/24), and 3) cylinder (model III; K = 1/4). The slope of the relationship between calculated Vlv and balloon volume varied between models (I, 0.71 +/- 0.11; II, 0.89 +/- 0.14; III, 1.07 +/- 0.17), and empiric determination of K to produce a slope of 1.0 resulted in a value of 0.26 +/- 0.04, not significantly different from the cylindrical model. Serial measurements of LV dimensions in 10 chronically instrumented conscious dogs revealed no significant change in end-diastolic or end-ejection LV shape after up to 16 wk of AR. Sonomicrometry and echocardiography can be integrated using a cylindrical geometric model to accurately estimate changes in end-diastolic or end-ejection Vlv during chronic volume overload.

Opacification and border delineation improvement in patients with suboptimal endocardial border definition in routine echocardiography: results of the Phase III Albunex Multicenter Trial.

OBJECTIVES: This study was designed to assess the safety and efficacy of intravenously administered sonicated human serum albumin for enhancing echocardiographic delineation of the left ventricular endocardium and improving assessment of wall motion in patients with incomplete depiction of noncontrast echocardiography. BACKGROUND: Echocardiographic regional wall motion analysis is impaired by incomplete endocardial definition in as many as 10% of patients. Sonicated human serum albumin is a stable contrast material that, unlike other agents, opacifies the left ventricle when administered intravenously. METHODS: One hundred seventy-five patients were enrolled at eight centers on the basis of incomplete echocardiographic endocardial depiction. Sonicated 5% human serum albumin, a stable preparation of air-filled microspheres (size range 1 to 10 microns), was administered intravenously in divided doses: 0.08 ml/kg body weight in all patients, followed by 0.14 and 0.08 ml/kg or a single dose of 0.22 ml/kg, depending on the result of the initial dose. Investigators and independent reviewers blinded to the protocol scored the echocardiograms for degree of left ventricular opacification and improvement of endocardial border depiction. RESULTS: Overall, 81% of patients had at least moderate left ventricular chamber opacification with at least one contrast dose, and endocardial definition was improved in 83%. In the subgroup with inadequate left ventricular opacification from the initial dose, a second, larger dose (0.22 ml/kg) improved endocardial depiction in 64%. No significant side effects occurred. CONCLUSIONS: In patients with incomplete echocardiographic endocardial definition, sonicated human serum albumin is a safe, effective contrast agent that, when administered intravenously, produces left ventricular chamber opacification, improves endocardial depiction and enhances regional wall motion analysis.

Etiology of large pericardial effusions.

PURPOSE: To determine the effectiveness of the preoperative evaluation and overall diagnostic efficacy of subxiphoid pericardial biopsy with fluid drainage in patients with new, large pericardial effusions. DESIGN: A prospective interventional case series of consecutive patients admitted with new, large pericardial effusions. PATIENTS AND METHODS: Fifty-seven of 75 consecutive patients admitted to a university tertiary-care center and a university-affiliated Veterans Administration Medical Center with new, large pericardial effusions were studied over a 20-month period. Each patient was assessed by a comprehensive preoperative evaluation followed by subxiphoid pericardiotomy. The patients' tissue and fluid samples were studied pathologically and cultured for aerobic and anaerobic bacteria, fungi, mycobacteria, mycoplasmas, and viruses. RESULTS: A diagnosis was made in 53 (93%) patients. The principle diagnoses consisted of malignancy in 13 (23%) patients; viral infection in 8 (14%) patients; radiation-induced inflammation in 8 (14%) patients; collagen-vascular disease in 7 (12%) patients; and uremia in 7 (12%) patients. No diagnosis was made in four (7%) patients. A variety of unexpected organisms were cultured from either pericardial fluid or tissue: cytomegalovirus (three), Mycoplasma pneumoniae (two), herpes simplex virus (one), Mycobacterium avium-intracellulare (one), and Mycobacterium chelonei (one). The pericardial fluid yielded a diagnosis in 15 (26%) patients, 11 of whom had malignant effusions. The examination of pericardial tissue was useful in the diagnosis of 13 (23%) patients, 8 of whom had an infectious agent cultured. Of the 57 patients undergoing surgery, the combined diagnostic yield from both fluid and tissue was 19 patients (33%). CONCLUSIONS: A systematic preoperative evaluation in conjunction with fluid and tissue analysis following subxiphoid pericardiotomy yields a diagnosis in the majority of patients with large pericardial effusions. This approach may also result in the culturing of "unusual" infectious organisms from pericardial tissue and fluid.

The learning curve for intraoperative echocardiography during congenital heart surgery.

Our group has previously reported a large prospective experience with the use of intraoperative echocardiography with Doppler color-flow imaging (IE-DCFI) during the repair of congenital heart defects. We have now performed IE-DCFI in 621 patients and have observed a major change in the impact of this technology, which has stabilized during our most recent experience (the last 207 patients). To evaluate the surgical learning curve with IE-DCFI, we divided patients into three groups: group 1, patients 1 through 207; group 2, patients 208 through 414; and group 3, patients 415 through 621. There were no major differences between groups with respect to age or disease entities. The average time needed to perform an IE-DCFI examination decreased from 3.75 +/- 1.77 minutes in group 1 to 3.35 +/- 1.52 minutes in group 2 and has remained stable. The number of patients requiring revisions in the operating room (based on IE-DCFI findings) decreased from 17 (8%) in group 1 to 7 (3%) in group 2 to 5 (2%) in group 3. Furthermore, revisions were 100% successful in correcting the problem in groups 2 and 3, whereas 18% of group 1 patients left the operating room with persistent residual defects by IE-DCFI. Surgeons can acquire the ability to interpret the results of IE-DCFI themselves and use it to enhance their operative repair of congenital heart defects, but this requires an experience of at least 200 cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnosis and management (by subxiphoid pericardiotomy) of large pericardial effusions causing cardiac tamponade.

To determine the clinical features, course and outcome of patients with cardiac tamponade, 57 consecutive patients with new, large pericardial effusions were prospectively studied. Twenty-five patients (44%) developed cardiac tamponade with venous hypertension and a pulsus paradoxus greater than 10 mm Hg. Electrocardiography, radiographic studies and echocardiography did not differentiate patients with and without tamponade. All 57 patients underwent thorough diagnostic evaluation followed by subxiphoid pericardial biopsy and drainage. A diagnosis was obtained in 53 patients (93%). Collagen vascular disease was significantly more frequent in the 25 patients with than in the 32 without cardiac tamponade (24 vs 3%; p less than 0.05). The frequency of malignant and uremic effusions was equal in both groups, whereas radiation-induced effusions seldom produced tamponade. At 1-year follow-up, 3 patients (12%) with tamponade had recurrent effusions, and 1 needed reoperation. This was not significantly different from the 32 patients without tamponade. Twelve-month mortality was also similar in both groups (36 vs 44%). This prospective series disclosed several unexpected findings: (1) Cardiac tamponade occurred in almost 50% of patients with new large pericardial effusions; (2) both malignancy and collagen vascular disease occurred with equal frequency as etiologies, whereas radiation-induced tamponade was unusual; (3) thorough clinical evaluation resulted in few idiopathic etiologies; and (4) subxiphoid pericardiotomy was effective for both diagnosis and therapy of tamponade.

Subxiphoid pericardiotomy in the diagnosis and management of large pericardial effusions associated with malignancy.

To determine the safety, diagnostic value, and clinical outcome of patients with malignancy undergoing subxiphoid pericardiotomy for large pericardial effusions, we prospectively studied 25 consecutive patients with malignancy and new, large pericardial effusions diagnosed by echocardiography. Twenty-two of the 25 operations were done under local anesthesia, and no patient died at surgery. Pericardial fluid cytology revealed malignant cells in 11 patients (44 percent), while tumor was seen in only five (45 percent) of these 11 patients on pathologic examination. The remaining 14 patients showed no evidence of pericardial invasion with tumor. Evidence of intrathoracic disease by CT or MRI scanning, tamponade, a sanguineous pericardial fluid character, and an elevated serum and pericardial fluid lactate dehydrogenase level all were suggestive of malignant invasion of the pericardium. All 25 patients were followed at least 12 months postoperatively. Effusions recurred in three patients (12 percent), and one patient required reoperation. Overall mortality was 72 percent with a 91 percent (10 of 11) mortality for those with malignant effusions and a 57 percent (8 of 14) mortality for those with nonmalignant effusions. Diagnostically, subxiphoid pericardiotomy has little advantage over examination of pericardial fluid alone in this group of patients. Therapeutically, however, it is a low morbidity procedure which is safe and effective in treating patients with malignancy and large pericardial effusions.

Safety and efficacy of sonicated albumin microspheres in perfusion and vein graft patency assessments.

This study was designed to identify a concentration of sonicated albumin microspheres that is safe, useful in determining graft patency, and provides an estimate of regional myocardial perfusion. The study included 8 patients between 50 and 72 years of age who were undergoing coronary artery bypass grafting. All patients were hemodynamically stable with left ventricular ejection fractions greater than or equal to 0.35. None had congestive heart failure or myocardial infarction within 4 months prior to the study. All had normal baseline neurologic and renal functions, and none had experienced allergic reactions to blood products or contrast dyes. A standard median sternotomy was performed for exposure of the heart at surgery, and saphenous veins were harvested and used for grafting. Intraoperative epicardial echocardiography (EE), always in the left ventricle short-axis at midpapillary level, was performed before and after grafting to determine regional myocardial wall motion. Sonicated albumin microspheres were prepared and injected into a single vein graft using an 18-gauge needle; 20 x 10(6), 100 x 10(6), and 200 x 10(6) microspheres were injected into the first graft sequentially. All other vein grafts were injected once with the dose that gave optimal contrast enhancement in the initial graft studied. In each patient, a minimum of 3 and maximum of 5 injections were performed, and graft perfusion was studied using EE. Graft flow, blood pressure, and electrocardiographic (ECG) measurements were continuously monitored, with a final EE performed after weaning the patient off cardiopulmonary bypass to assess wall motion. Preliminary results showed that no patient had adverse effects during or after the study and all remained hemodynamically stable.(ABSTRACT TRUNCATED AT 250 WORDS)

Routine use of intraoperative epicardial echocardiography and Doppler color flow imaging to guide and evaluate repair of congenital heart lesions. A prospective study.

Routine epicardial two-dimensional echocardiography, Doppler, and Doppler color flow imaging studies were performed before and after cardiopulmonary bypass in 328 patients undergoing operations for congenital heart disease. Ages ranged from 1 day to 59 years (mean 5.9 years); the smallest patient was 1.8 kg. Complete examinations were conducted in 3.6 +/- 1.7 minutes. Prebypass examinations demonstrated previously unappreciated details of anatomy in 60 patients (18%), which did not relate to whether catheterization had been performed, and they were believed to play a role in surgical planning in 143 patients (44%). Discovery of previously unrecognized features of anatomy increased the impact of echo-Doppler color flow imaging on operative planning by 2.5 times. After bypass, echo-Doppler color flow imaging disclosed unsuspected residual defects in 22 patients (7%) who were doing well clinically and enabled an attempt at immediate revision of the procedure. When ultimate clinical outcome was compared to postbypass findings of echo-Doppler color flow imaging, the presence of a residual defect, right or left ventricular dysfunction, or any concern with the heart by echo-Doppler color flow imaging appeared to serve as a predictor of unfavorable outcome (p less than 0.001 for each when compared with absence of these difficulties). Thus routine intraoperative echo-Doppler color flow imaging is useful in aiding the planning, conduct, and assessment of results in operations for congenital heart disease.

The use of intraoperative echo with Doppler color flow imaging to predict outcome after repair of congenital cardiac defects.

Surgical repair of congenital cardiac defects (CCD) has undergone a remarkable evolution in the past decade. Major defects are now often completely corrected in early infancy with continually improving rates of survival. It has become clear that the next major focus will be improvements in the long-term quality of life and this has promoted many innovations in surgical technique and approach. One advance is the use of intraoperative echo with Doppler color flow imaging (echo-DCFI) to evaluate the exactness of operative repair. Aside from anecdotal reports, very little information is available regarding the interpretation of images produced by this technology in the operating room. Furthermore there have been no studies addressing the predictive value of intraoperative echo-DCFI findings with respect to outcome for patients undergoing repair of CCD. The prospective data obtained by following the course of 273 patients receiving intraoperative echo-DCFI has been reviewed after repair of a variety of CCD (age range, 1 to 53 years; mean 5.3 years; smallest patient, 1.8 kg). Forty-seven patients (17%) had initially unacceptable results, by echo, at the completion of their repair. Eighteen of these patients (7% of entire series) had no clinical problems and the defects were discernible only by echo. Twenty-six patients with initially unacceptable results had their repairs revised in the operating room and left with an acceptable result by echo. Twenty-one patients were allowed to leave the operating room with echo-discernible defects. Follow-up of these patients demonstrated a significantly higher (p less than 0.006) rate of reoperation (42% vs. 3%) and of early death (29% vs. 10%) for those patients whose defects were left unrepaired compared to those whose problems were corrected before leaving the operating room. Sixty-eight patients (25%) had some alteration of ventricular function (compared to their prebypass evaluation) at the completion of their repair. Regardless of whether the dysfunction was limited to the right ventricle, left ventricle, or was biventricular, patients in this group had a significantly higher incidence (p less than 0.004) of early, but not late, death compared to patients without alteration of ventricular function (35% vs. 4%). Patients who left the operating room with no problems of concern by echo-DCFI had a greater than 90% likelihood of a long-term acceptable outcome compared to patients who had any problem of concern (residual defect, anatomic or technical imperfection, ventricular dysfunction, and so on) whose long-term likelihood of an acceptable outcome approached 50% (p less than 0.0125).(ABSTRACT TRUNCATED AT 400 WORDS)

Intraoperative prebypass and postbypass epicardial color flow imaging in the repair of atrioventricular septal defects.

The use of intraoperative epicardial Doppler echocardiography with color flow imaging both before and after cardiopulmonary bypass to assist repair of congenital heart defects in infants and small children has not been reported. To demonstrate its simplicity and utility, we obtained immediately prebypass and postbypass examinations from 18 consecutive patients undergoing repair of atrioventricular septal defects between March 1987 and March 1988 (aged newborn to 3 years, smallest 2.4 kg, 11 patients less than 1 year old). Direct application of a sterile transducer to the epicardial surface eliminates any restriction imposed by the transesophageal approach, and the routine use of color flow imaging enables the operating surgeon to directly evaluate intracardiac anatomy and flows in a variety of orientations. Average examination time was 3.95 +/- 1.96 minutes. Prebypass studies disclosed that a short-axis inspection through the common atrioventricular valve orifice produced a unique visualization of the dynamic commitments of atrioventricular valve tissue throughout systole and diastole that was helpful in planning valve allocation during repair. In addition, echocardiography demonstrated features not previously appreciated in seven of 18 patients (39%). In all, image quality and resolution were vastly superior to preoperative chest wall studies. Postbypass studies revealed significant residual interventricular shunts in two of 18 patients (11%). Views obtained from various orientations directed specific and efficient repair immediately so that all patients left the operating room with documented, surgically acceptable results. Comparison of ventricular function between prebypass and postbypass studies enabled appropriate application of pharmacologic agents in the operating room if necessary. All patients survived their operation. There have been two late deaths, and 16 patients are alive and doing well (follow-up: 9 to 21 months). These experiences indicate that intraoperative epicardial Doppler color flow imaging (1) can be easily learned and applied by the surgeon, (2) enhances the repair of atrioventricular septal defect by providing unique spatial, anatomic, and flow information in the beating heart at the time of repair, (3) increases confidence of a surgically acceptable repair before the patients leave the operating room, (4) guides specific surgical or anesthetic adjustments to optimize results, and (5) works as a valuable aid that may help reduce poor results in the repair of complex congenital cardiac lesions.