Assessment of myocardial viability with 99mTc sestamibi in patients undergoing cardiac transplantation. A scintigraphic/pathological study.

BACKGROUND: 99mTc sestamibi and 201 Tl are tracers that allow equivalent detection of myocardial infarction. However, because sestamibi does not undergo as much time-dependent redistribution as does 201Tl, it has been considered suboptimal for the detection of myocardial viability. METHODS AND RESULTS: Fifteen consecutive patients with ischemic cardiomyopathy who underwent orthotopic cardiac transplantation received an intravenous injection of 99mTc sestamibi at 1 to 6 hours before transplantation. Rotational tomography of the excised, intact, native hearts was performed to quantify the extent of myocardial hypoperfusion. The hearts were then sliced and reimaged on a gamma camera, followed by pathological quantification of the extent and severity of scarred and normal myocardium. Samples of normally and abnormally perfused myocardium underwent gamma well counting to determine tissue radioactivity and were examined under light microscopy for delineation of myocardial structure after trichrome staining. The mean extent of scintigraphic scar quantified through the use of rotational tomography was 45 +/- 14% of the left ventricle and correlated closely with pathological scar size (r = .89), despite a slight overestimation. Scintigraphic scar size determined with planar imaging of the individual myocardial slices also correlated closely with pathological scar size (r = .88). A good correlation existed between tissue 99mTc sestamibi activity determined through well counting and histological evidence of myocardial viability (r = .89). Most hypokinetic and 40% of akinetic/dyskinetic myocardial segments contained scintigraphically and histologically normal myocardium. CONCLUSIONS: 99mTc sestamibi scintigraphy can be used to accurately quantify the extent of myocardial scarring. Furthermore, the relative sestamibi activity in perfusion defects, measured several hours after administration, is a good indicator of myocardial viability determined with microscopy.

Long-term follow-up of heart transplant recipients requiring permanent pacemakers.

BACKGROUND: Permanent pacemaker implantation after heart transplantation is contentious. Indications for these devices in this population are uncertain. The goals of this project were to (1) analyze the time course of donor sinus node dysfunction and atrioventricular block after heart transplantation; (2) evaluate which selected parameters (donor age, ischemic time, heart rate before pacer insertion, and number of rejection episodes) might relate to persistent permanent pacing need, and (3) assess pacemaker complications during follow-up. METHODS: A retrospective analysis of pacemaker implantations (22 cases) was performed in 286 consecutive heart transplantations performed between February 1984 and April 1994 at The Methodist Hospital and Baylor College of Medicine, Houston, Texas. RESULTS: Permanent pacemakers were inserted early after transplantation in 19 patients (mean 24 days); 14 pacemakers were for sinus node dysfunction (bradycardia in five, sinus arrest with junctional escape in eight, and optimization of hemodynamics in one). Symptomatic complete heart block prompted insertion late in two patients (3 and 47 months), and symptomatic sinus pause was the indication for late insertion in one. Recipient mean age was 52.4 years, with mean donor age 29.7 years in patients with pacemakers. By 3 months, 13 of 19 patients receiving pacemakers early (mean preinsertion heart rate 58.3 beats/min) became pacer independent with subsequent mean intrinsic heart rate of 97 beats/min. Recipient or donor age, ischemic time, and rejection episodes did not appear related to long-term pacing need early or late after transplantation. CONCLUSIONS: Inferences from these observations include the fact that many patients with early sinus node dysfunction and bradycardia are not pacer dependent at 3 months. However, those with atrioventricular block early appear to require long-term pacing support. However, the possibility that more aggressive and long-term oral chronotropic medication use after transplantation would obviate early permanent pacemaker need is not addressed. Finally, prospective clinical trials are necessary to precisely characterize benefit of permanent pacemakers and define optimal pacing modes after heart transplantation.

Clinical impact of transesophageal echocardiography in the diagnosis and management of infective endocarditis.

Transesophageal echocardiography (TEE) has assumed a prominent role in the diagnosis and management of infective endocarditis (IE). The impact of negative TEE findings on the management of patients suspected of having IE is not clear. To better understand how a negative TEE examination would influence patient management, the medical records of 93 consecutive patients undergoing TEE to evaluate for IE were examined. The influence of TEE was assessed based on changes in diagnosis, antibiotic therapy, or the need for surgical intervention during hospitalization. The negative predictive value of TEE was found to be 100% in native valves and 90% in prosthetic valves. The overall impact of negative TEE findings was significant in terms of final diagnosis and duration of antibiotic therapy (a negative TEE resulted in 60% reduction in antibiotic duration, p = 0.0001). These findings suggest that in patients with native heart valves, a negative TEE examination virtually excludes IE. In patients with prosthetic valves, a negative TEE significantly decreases the likelihood of IE but does not completely exclude the diagnosis; therefore, in this setting, a negative finding should be closely correlated with the clinical course.

Heterotopic heart transplantation: catheterization, endomyocardial biopsy, and coronary angiography of the donor heart.

UNLABELLED: Follow-up after heart transplantation presently requires invasive techniques to assess graft viability and function. As the heterotopic transplant technique assumes a more important therapeutic role for patients not eligible for an orthotopic allograft, an understanding of the inherent challenges associated with management of these patients is mandatory to optimize patient care. Heterotopic transplant technique was used in 19 of 135 (14%) consecutive heart transplant procedures over a 41 month period. Invasive diagnostic procedures performed in follow-up revealed 1) adequate tissue for histologic evaluation in 140/158 (89%) biopsy procedures, 2) successful pulmonary wedge pressure measurements in 142/158 (90%) right heart catheterizations, and 3) successful coronary arteriography in 18 patients undergoing angiography (both vessels in 12 and one vessel in six patients). Thus, biopsy and surveillance procedures are feasible and productive in patients who have undergone heterotopic heart transplantation. BACKGROUND: Although heterotopic heart transplantation has become an increasingly utilized therapy for some patients with heart failure, there are no guidelines for routine biopsy and angiographic techniques in these patients. The objective of this study was to determine the feasibility of angiographic and endomyocardial biopsy procedures in heterotopic heart transplant recipients. METHODS: The complete experience with heterotopic heart transplant recipients at Baylor College of Medicine and The Methodist Hospital over a 41 month period including endomyocardial biopsy, right heart catheterization, and selective coronary arteriography results were analyzed. RESULTS: Eighteen patients underwent 310 procedures without significant complications. Of 158 biopsy procedures, 140 (89%) yielded tissue adequate for histologic evaluation. Right heart pressures were obtained in almost all patients undergoing right heart catheterization. Pulmonary wedge pressures were obtained in 137 (90%). A rapid decrease in right heart pressures was noted following transplant; however, a gradual but significant rise in mean arterial pressure occurred. Eighteen selective coronary arteriogram procedures were performed; 12 (66%) resulted in successful cannulation of both coronary arteries. Of 12 patients followed for at least 1 year, five (40%) have developed evidence of allograft arteriopathy. The 1 and 2 year survival rates were 67% and 53%, respectively. CONCLUSIONS: Invasive diagnostic techniques can be performed safely and reliably and should not preclude the use of heterotopic heart transplantation in selected patients who are otherwise unsuitable for orthotopic transplantation.

Is intravascular ultrasound better than quantitative coronary arteriography to assess cardiac allograft arteriopathy?

Optimal methods to detect and quantify allograft arteriopathy have not been established. Both arteriography and intravascular ultrasound have been used to evaluate vessel lumen diameter and area and arterial wall thickness in patients following cardiac transplantation, although due to the anatomically diffuse nature of this disease, neither technique has been accepted as the diagnostic "gold standard". To determine the usefulness of quantitative angiography to detect transplant-related coronary artery disease compared to intravascular ultrasound, 25 patients underwent both procedures following cardiac transplantation (20 < 1 year, 5 > 1 year). Lumen diameter and area measurements of proximal coronary artery segments were compared using both techniques. Overall, lumen diameter and area measurements correlated closely between the two procedures, both for the early and late follow-up patients. However, because of the ability to characterize changes more precisely in coronary vessel shape and wall thickness, intravascular ultrasound offered distinct advantages over routine coronary angiography and is probably the technique of choice to evaluate allograft arteriopathy.

What are the implications of cardiac infection with cytomegalovirus before heart transplantation?

To elucidate prognostic implications of recipient cytomegalovirus infection before heart transplantation, we prospectively followed the clinical outcome of 21 transplant recipients whose explanted hearts (myocardium and coronary arteries) were first examined for the presence of cytomegalovirus DNA with polymerase chain reaction. Subsequently, serial endomyocardial biopsy tissue samples obtained from the allograft during routine evaluation for rejection were analyzed by polymerase chain reaction for both an immediate early and late cytomegalovirus gene region of cytomegalovirus DNA. Humoral cytomegalovirus immunoglobulin G antibodies were also measured by radioimmunoassay. Both early and late antigens were present in 14 of 21 (67%) explants from patients with (12 of 15 explants) and without (2 of 6 explants) pretransplant cytomegalovirus antibodies. Although the presence of both early and late antigens was uncommon in allografts the first week after transplantation (5 of 20 allografts, 25%), their presence significantly increased at 1 month (14 of 21 allografts, 67%) and 2 to 3 months (13 of 17 allografts, 77%) regardless of pretransplantation cytomegalovirus antibody status. The presence of both early and late antigens in explant tissue strongly predicted allograft virus status during the follow-up periods. Of five patients in whom clinical cytomegalovirus disease subsequently developed, all had explants positive for both early and late antigens, and all allografts were positive for early and late antigens within 1 month after transplantation. These are the first prospective data to correlate pretransplantation serum antibodies and explant polymerase chain reaction status with the development of future allograft infections and overall clinical outcome.

Transesophageal echocardiographic demonstration of right coronary artery-to-coronary sinus fistula in a heart transplant recipient.

A fistula between the distal right coronary artery and coronary sinus was detected by transesophageal echocardiography in a heart transplant recipient. Cineangiograms confirmed this finding to be new since the time of angiography one year earlier. Although coronary artery-to-right ventricular fistulas are not an uncommon complication of endomyocardial biopsy, the echocardiographic findings of a fistula involving the coronary sinus have not been previously described.

Calcium infusion increases plasma atrial natriuretic factor in spontaneously hypertensive rats.

The effect of calcium on plasma atrial natriuretic factor (ANF) concentration was determined in spontaneously hypertensive rats (SHR) and their control, Wistar-Kyoto (WKY) rats. CaCl2 10.5 mg (0.095 mmol) in 0.54 ml 5% glucose or an equal volume of vehicle alone was infused intravenously for 30 minutes into conscious precannulated SHR (vehicle, n = 16; CaCl2, n = 16) and WKY rats (vehicle, n = 25; CaCl2, n = 15). Direct systolic blood pressure was measured throughout the infusion period. Blood samples for serum total calcium and plasma ANF were obtained at the end of each experiment. The systolic blood pressure did not change significantly during infusion of the vehicle or CaCl2 in either strain. No significant difference was observed in serum total calcium concentration between SHR and WKY rats after vehicle (9.8 +/- 0.1 [mean +/- SEM] mg/dl vs. 10.0 +/- 0.1) or after CaCl2 infusion (12.2 +/- 0.3 vs. 12.2 +/- 0.2). Plasma ANF concentrations after both vehicle and CaCl2 infusion were significantly higher in SHR than in WKY rats (vehicle, 211 +/- 24 pg/ml vs. 129 +/- 11, p less than 0.05; CaCl2, 395 +/- 21 vs. 278 +/- 33, p less than 0.05). There were high degrees of correlation between serum total calcium and plasma ANF both in SHR (r = 0.77, p less than 0.001) and in WKY rats (r = 0.76, p less than 0.001). No significant difference was observed in the slopes of the regression lines of ANF as a function of the serum total calcium concentration between SHR and WKY rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Children's vision--a 20/20 outlook.

Twenty years ago, A. M. Skeffington, O.D., talked about the "uniqueness" of optometry which included prevention, remediation and enhancement. Fifteen years ago, Arnold Gesell, M.D., urged optometry to pay attention to the preschool years and to examine and supervise (with optometric expertise) the vision of these children and to learn to identify those children who would present difficulties in learning. At the same time, Darell Boyd Harmon, Ph.D., suggested that optometry "gear up" for an expected avalanche of visually-related learning problems. Optometry did listen and learn, the avalanche is here and developmental optometry has prospered. This paper briefly explores some of the long and short-range benefits of vision therapy.