Bernhard A

Dimensions of the great arteries, semilunar valve roots, and right ventricular outflow tract during growth: Normative angiocardiographic data

SummarySystolic and diastolic diameters of the right and left pulmonary arteries (RPAD, LPAD), descending thoracic aorta (DTAD), right ventricular infundibulum (RVID), and pulmonary and aortic valve roots at the proximal, commissural and distal levels were estimated from angiocardiograms in 24 infants, children, and adolescents without heart disease, and correlated with body surface area (BSA), stroke volume (SV), cardiac output (CO), and ventricular volumes.The relationships between cardiovascular diameters and BSA were better expressed by a power function than by the other functions tried. We obtained different exponents for pulmonary and aortic valve annuli and the more distally measured great arteries (RPAD, LPAD, and DTAD), suggesting different growth patterns. The right ventricular infundibular shortening fraction (RVISF) was weakly correlated with BSA (r=-0.328), and the values obtained indicated constancy during normal growth. There was a direct proportional relationship between the pulmonary valve annulus diameter and the cube root of the right ventricular volume (r=0.952), as well as between SV and cross-sections of the right pulmonary artery (RPAC;r=0.916), left pulmonary artery (LPAC;r=0.878) and descending thoracic aorta (r=0.962). RPAC and LPAC were strongly correlated (r=0.940), the RPAC being significantly larger than the LPAC.

Left and right ventricular adaptation to right ventricular overload before and after surgical repair of tetralogy of Fallot

On the basis of angiographic projections, left (n = 43) and right (n = 56) ventricular volume data were obtained in patients with tetralogy of Fallot before and after surgical repair. The postoperative patients were divided into 3 groups according to the degree of an additional volume load secondary to a residual ventricular septal defect or pulmonary insufficiency, or both. The decreased left ventricular ejection fraction (p less than 0.01) in preoperative tetralogy of Fallot in the presence of a normal sized left ventricle suggests depressed global myocardial function, which is not improved after surgical repair, even if excellent results are achieved. A certain functional reserve, however, seems to be preserved, since the ejection fraction did not decrease further with increasing additional volume loads. Similar enlargement of the right ventricle secondary to comparable degrees of pulmonary insufficiency and residual ventricular septal defect indicates similar effects of additional diastolic and systolic filling on right ventricular function in patients with tetralogy of Fallot after surgical repair. Even in patients with excellent surgical results, such as those without significant right ventricular outflow tract obstruction and additional volume load, right ventricular pump function is depressed, the ejection fraction being significantly (p less than 0.01) lower than normal. The further decrease of global myocardial function with increasing volume load suggests a loss of functional reserve. Attempts to minimize right ventricular volume load after surgical repair seem advisable.

A new device for slow progressive narrowing of vessels

SummaryThe purpose of this work was to develop a device which allows slow progressive banding of a great artery in infants within 4 to 5 weeks. Employed was the hygroscopic casein ameroid. When brought in contact with fluids, an ameroid cylinder expands characteristically. An early phase of fast expansion proceeds gradually to a phase of slow growth. Size, shape, and encasement of ameroid as well as temperature and type of surrounding fluid modify but do not alter the typical pattern of expansion. The developed constrictor (weight: 5.8 kg, length: 18 mm, diameter: 12 mm) includes a stainless steel socket containing an ameroid cylinder (length: 8.5 mm, diameter: 8 mm). The expanding ameroid pushes a piston with a concave extension (makrolon) a maximum of 2 mm against the artery, which is fixed to the metal housing by a teflon band (width: 4 mm, thickness: 0.5 mm). The band runs in 2 fitting grooves on the metal housing to which it is fixed by a metal ring with a precisely manufactured internal thread allowing exact tightening and loosening of the band around the artery.Utilization of inert materials like teflon, makrolon, and stainless steel warrents experimental and possibly clinical application of the developed small constrictor.

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.

Influence of the two-stage anatomic correction of simple transposition of the great arteries on left ventricular function

To evaluate the influence of the 2-stage anatomic correction of simple transposition of the great arteries on left ventricular (LV) function, pressure and angiocardiographic volume data were analyzed during resting conditions shortly before banding of the pulmonary trunk (n = 12) and before (n = 17) and after anatomic correction (n = 11), and compared with data from controls (n = 12). Age at banding and anatomic correction was between 1 and 44 months (mean 16 +/- 10) and between 13 and 47 months (mean 24 +/- 10), respectively. The interval between anatomic correction and the investigation ranged from 10 to 29 months (mean 20 +/- 7). After banding, LV ejection fraction decreased (p less than 0.01) and LV peak systolic pressure (p less than 0.01) as well as LV end-diastolic pressure (p less than 0.05) increased. After anatomic correction, these variables and LV end-systolic wall stress were not significantly different from control values. The LV end-systolic wall stress-ejection fraction relation in 7 of 11 patients after anatomic correction was within control range. The highest values were found in the youngest patients at banding and at anatomic correction. In contrast to measures of global myocardial function, such as LV ejection fraction and LV end-diastolic pressure data, the LV end-systolic stress-ejection fraction relation suggest that LV function may not be normal in some patients 20 months after anatomic correction. Young age at operation, however, appears to be advantageous in preserving LV function. Hemodynamic alterations after banding probably reflect LV adaptation to systemic pressures in a hypoxemic circulation.

Response of the right ventricle to progressive pressure loading in pigs

SummaryThe purpose of this study was to determine the speed and duration of progressive pressure loading of the right ventricle to systemic pressure levels, which allows right ventricular adaptation without myocardial impairment at rest.In 8 pigs with an average weight of 22 kg progressive right ventricular pressure loading of different speeds and durations was induced with a newly developed constrictor. Pressures in the right atrium, right ventricle, and pulmonary artery as well as angiocardiographic volume parameters of the right ventricle were determined weekly over a period of 4 to 7 weeks. A fast progressive right ventricular pressure increase of 3.4 mm Hg/day during 3 weeks was associated with a 20–30% reduction of ejection fraction and a 100% increase of the end-systolic volume. Increase of end-diastolic pressure was 3 to 5 fold. A slow progressive pressure increase of 1.5 to 2.2 mm Hg/day to 100 mm Hg within 4 to 5 weeks was associated with an increase of the end-diastolic pressure to a level observed in systemic ventricles, while change of ejection fraction and end-systolic volume was minimal. The faster the increase of right ventricular pressure the flatter was the peak systolic pressure/end-systolic volume relationship.It is concluded that in contrast to sudden and fast progressive increase of afterload slow progressive increase of afterload to systemic levels does not impair right ventricular myocardial function.

Continuous venovenous haemofiltration in neonates with renal insufficiency resulting from low cardiac output syndrome after cardiac surgery.

Acute renal insufficiency is a common complication after surgery for congenital cardiovascular defects in neonates and is associated with a high incidence of morbidity and mortality. The authors reviewed their experience with continuous venovenous haemofiltration in neonates and infants with acute renal insufficiency resulting from low cardiac output following cardiovascular surgery. Twelve critically ill patients with pharmacologically intractable fluid overload were treated with continuous venovenous haemofiltration over a period of 42 months. All patients were mechanically ventilated and dependent on high doses of catecholamines. Continuous venovenous haemofiltration was started 64.2(28.2) h postoperatively and maintained for a period of 8 to 195 h. A negative fluid balance was achieved in all patients (2.1(0.5) ml/kg per h). No complications relating to continuous venovenous haemofiltration were evident during the treatment. The survival rate was 59% (seven of 12). Continuous venovenous haemofiltration is a valid and simple method for controlling fluid overload in neonates and infants with low cardiac output.

Atrial natiuretic peptide release at rest and with exercise after cardiac transplantation with bicaval anastomoses

Bicaval anastomoses in orthotopic cardiac transplantation offer the advantage of preserving the right atrial geometry. To elucidate the impact of this anastomotic technique on atrial natriuretic peptide plasma levels at rest and with exercise, nine patients were submitted to a symptom-limited supine exercise test. Atrial natriuretic peptide plasma levels in samples obtained from the right atrium were elevated at rest (274.4 +/- 60.4 pg/ml), at peak exercise (438.1 +/- 71.7 pg/ml), and thereafter (328.1 +/- 71.2 pg/ml) with respect to normal reference values of 21 +/- 1 pg/ml at rest and 92 +/- 14 at peak exercise. Renin, angiotensin, and aldosterone plasma levels were almost normal and did not indicate any pathologic processes in volume homeoostasis. Right-sided hemodynamic parameters were not correlated with atrial natriuretic peptide secretion. An adverse relationship between cold ischemic time of the donor organ and atrial natriuretic peptide release was found (r = 0.88, p < 0.0008), indicating that endocrine cardiocytes are sensitive to prolonged ischemia. Atrial natriuretic peptide release may thus be independent of the surgical approach, and other unique characteristics of the transplanted heart, such as denervation, are more likely to be responsible for elevated atrial natriuretic peptide plasma concentrations after orthotopic heart transplantation.

Unstented and Partial Stented Bioprostheses for Aortic Valve Replacement-Up to 6 Years of Follow-Up

Since January 8,1985, three different designs of unstented (type A, n = 9) and partial stented (type B, n = 4; and type C, n = 3) glutaraldehyde preserved porcine aortic valves were used for aortic valve replacement in 16 patients with acquired aortic valve lesions. Type A and type B prostheses were Implanted using a two suture row technique. In type C prostheses, only a single suture row was necessary for implantation, facilitating surgery considerably. In all patients, the fully flexible commissures of the bioprostheses were secured to the aortic wall of the recipient. There was no hospital mortality. Two patients with type A bioprostheses died due to noncardiac causes, 4 and 24 months postoperatively. One bioprosthesis in this group had to be replaced after 3 months because of insufficiency. Serial Doppler echocardiographic studies were performed up to 6 years after implantation. No significant leaflet calcification was observed. In three type A bioprostheses, a mild insufficiency without progression was recorded. The latest mean/peak transprosthetic pressure gradients were: type A: 6 ± 4 mmHg/12 ± 6 mmHg; type B: 6 ± 3 mmHg/14 ± 5 mmHg; and type C: 11 ± 5 mmHg/18 ± 8 mmHg. The functional results of the type A and type B bioprostheses have proven to be satisfactory. The slightly higher pressure gradients in patients with a type C bioprosthesis give rise to further refinements of its design. These results confirm the usefulness of imitating normal anatomy by using unstented or partial stented bioprostheses.

Repair of anomalous origin of the right pulmonary artery from the ascending aorta associated with subtotal left cor triatriatum.

A unique case of anomalous origin of the right pulmonary artery from the ascending aorta associated with subtotal left cor triatriatum and severe pulmonary hypertension in a 4-month-old infant was successfully repaired using cardiopulmonary bypass and circulatory arrest.