Frederick W. Arensman

Left ventricular contractility and contractile reserve in humans after cardiac transplantation.

Limited data are available concerning left ventricular contractility and contractile reserve in the chronically denervated, transplanted human heart. This is primarily because of the inability of traditional tests of left ventricular performance to distinguish changes in contractility from alterations in ventricular loading conditions. In this study, load-independent end-systolic indexes of left ventricular contractility were measured by echocardiography and calibrated carotid pulse tracings in 10 patients who had undergone orthotopic cardiac transplant (age 48 +/- 4 years; interval from operation to study 1.2 +/- 0.8 years) and in 10 normal control subjects (age 25 +/- 4 years) matched for donor heart age (25 +/- 6 years). None of the transplant patients had evidence of rejection as determined by endomyocardial biopsy. Baseline left ventricular contractility was assessed over a wide range of afterload generated by infusion of methoxamine. Contractile reserve was measured as the response to an infusion of dobutamine plus methoxamine. Before afterload challenge, baseline left ventricular percent fractional shortening was higher for the transplant patients than for the control subjects (36.5 +/- 5.7% vs 32.1 +/- 2.1%; p less than .05). These differences occurred at a time that end-systolic wall stress (a measure of afterload) was significantly lower for the transplant patients (38 +/- 16 vs 50 +/- 9 g/cm2; p less than .05). When the left ventricular end-systolic pressure-dimension and stress-shortening relationships were determined for the transplant and control subjects, no differences in contractility or contractile reserve were noted. Thus the chronically denervated, transplanted, nonrejecting human left ventricle demonstrates normal contractile characteristics and reserve.

Influence of two-stage anatomic correction on size and distensibility of the anatomic pulmonary/functional aortic root in patients with simple transposition of the great arteries.

To evaluate the results of the two-stage anatomic correction of simple transposition of the great arteries the size, distensibility, and histologic characteristics of the anatomic pulmonary root, which arises from the anatomic left ventricle and which we termed the functional aortic root after anatomic correction, were determined in seven patients before and twice after anatomic correction (mean 43 and 671 days) and the results were compared with those in normal control subjects. The diameter of the systolic sinus of the anatomic pulmonary root increased after banding on the average to 140% of normal, whereas the diameter of the diastolic sinus of the functional aortic root increased after anatomic correction on the average to 150% of normal. Diameters of both the systolic and diastolic sinuses of the functional aortic root remained 30% to 55% larger than normal after anatomic correction. Growth potential of the functional aortic root after anatomic correction was normal, whereas its distensibility, as assessed by determination of the percent change in radius and pressure-strain elastic modulus (stiffness index), was decreased after anatomic correction. This pressure-strain elastic modulus was directly related to the corresponding body surface area and age at banding. In four of five specimens of the anatomic pulmonary arterial wall that were obtained at the time of anatomic correction, fragmentation and shortening of elastic fibers were observed. The histologic characteristics of the pulmonary root in the patient with the smallest body surface area at banding and normal distensibility of the anatomic pulmonary/functional aortic root before and after anatomic correction revealed normal aortic configuration of the elastic tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheter evaluation of left ventricular shape and function 1 or more years after anatomic correction of transposition of the great arteries

Twenty-eight children were reinvestigated by cardiac catheterization and angiography greater than 1 year after anatomic correction of transposition of the great arteries (TGA). Seventeen patients with simple TGA underwent banding of the pulmonary trunk plus or minus systemic to pulmonary artery shunt to prepare the left ventricle for anatomic correction. In addition to TGA, 10 of the remaining 11 patients had a large ventricular septal defect and 1 had an aorticopulmonary window. They required no preparation of the left ventricle. Age at repair ranged from 2 to 120 months (mean 26). Catheterization 12 to 48 months after anatomic repair revealed a left ventricular end-diastolic pressure of 4 to 14 mm Hg (mean 9.5 +/- 2.5 [+/- standard deviation]). Ejection fraction ranged from 52 to 75% (mean 66 +/- 8). Frame-by-frame computer-assisted analysis of left ventricular (LV) contraction and relaxation was performed in 14 patients and compared with normal left ventriculograms. Shape index, derived as 4 pi X cavity area/perimeter2 X 100, was measured in 24 patients and showed a mean index of 89 +/- 3% at end-diastole and 79 +/- 8% at end-systole. A control group had a mean diastolic index of 86 +/- 6% and mean systolic index of 73 +/- 8%. It is concluded that LV shape after anatomic correction tends to be more globular than normal and changes little during systole. LV ejection fraction and end-diastolic pressure are normal.

Cardiac rhythm and conduction before and after anatomic correction of transposition of the great arteries

To assess pre- and postoperative arrhythmias associated with anatomic correction of transposition of the great arteries, 34 patients had 145 standard electrocardiograms (ECGs) and 24 of these patients had 46 24-hour ECGs from 11 months before to 54 months after anatomic repair. Twenty-two patients underwent balloon atrial septostomy and 7 surgical atrial septectomy before the initial 24-hour ECG. Anatomic correction included repair of a large ventricular septal defect in 16 patients and an aortopulmonary window in 1 patient. The preoperative standard ECG showed sinus rhythm in every patient. Preoperative 24-hour tapes revealed sinus arrhythmias in 2, sinus bradycardia at a rate of less than or equal to 50 beats/min in 1, junctional rhythm in 1 and rare premature ventricular contractions (PVCs) in 1. The postoperative 24-hour ECG showed atrioventricular dissociation in 1 patient, rare premature atrial contractions in 7, rare PVCs in 8 and sinus bradycardia with junctional escape in 1. Eight patients had PVCs on the postoperative ECG that were not noted on preoperative tapes. No patient had prolonged bradycardia (less than or equal to 50 beats/min), life-threatening arrhythmias or sudden death. Except for 1 patient with atrioventricular dissociation believed to be secondary to a preventable cause, 34 patients followed for 890 patient-months after anatomic correction for transposition of the great arteries had no significant arrhythmias.

76 DIGITIZED ECHOCARDIOGRAPHIC ASSESSMENT OF LEFT VENTRICULAR WALL MOTION IN INFANTS AND ADOLESCENTS WITH SICKLE CELL ANEMIA

To examine ventricular wall motion in sickle cell anemia (SS), two groups of SS patients (pts) underwent digitized echocardiographic analysis. Group I consisted of 30 SS infants (mean age 0.8 yrs). Group II consisted of 70 SS pts (mean age 13.8 yrs). When these groups were compared to nonanemic controls (C) of similar age, no differences were found in shortening fraction or systolic time intervals. Computer derived information included: R-R interval, maximum (Max) and minimum (Min) LV size, Max and Min septal and freewall thickness, Max rate of septal and freewall thickening and thinning. Timing of each event was normalized as a percentage of the total R-R interval. Mean value ± standard deviation and a p value for various groups are shown below:Adolescents with SS have abnormalities of LV dimension and wall motion which are not present in infancy. Systolic delay in achieving Min LV size may be secondary to increased stroke volume. The etiology of diastolic delay septal thinning and max cavity filling is unknown.

77 ASSESSMENT OF CORONARY AND AORTIC ANASTOMOSES FOLLOWING ANATOMIC CORRECTION OF TRANSPOSITION OF THE GREAT ARTERIES

Anatomic correction of transposition of the great arteries (TGA) is usually done at a young age and always entails circumferential anastomoses of the aorta and coronary arteries. Longterm success of this procedure is predicated on adequate growth of these anastomotic sites. To assess these anastomoses, 25 patients (pts) underwent one or two cardiac catheterizations frcm 1 to 53 months (mean 18.8 months) following anatomic correction. Early catheterizations (mean 12 months following repair) were performed in 23 pts and late studies (mean 30 months following repair) in 13. Age at repair ranged from 2 to 168 months, and 15 pts were less than one year of age. Fifteen pts had undergone previous pulmonary artery banding in preparation for anatomic repair. Five distinct aortic diameters were measured on AP and lateral angiograms. Measurements were made at the anastomotic site, proximal, and distal to the anastomosis. Nearly all diameters of the aorta were larger than control values. There were no differences in early and late postoperative measurements. There were no differences when previously banded pts were compared to non-banded pts. No patient had a pressure gradient measured across the aortic anastomosis. Subjective examination of the coronary arteries showed no areas of kinking, narrowing or tortuosity and there was never ECG evidence of ischemia.We conclude that coronary and aortic anastomoses allow for satisfactory growth following anatomic correction of TGA even when there has been prior pulmonary artery banding. The large ascending aorta does not appear to undergo progressive dialation following anatomic correction.