Search PubMed⌕ Search

Biomedical subjects

P H Heintzen

Publications and source records attributed to P H Heintzen.

At least 19 recordsLinked to original sources
PubMed1993

Superior function of a bicuspid over a monocuspid patch for reconstruction of a hypoplastic pulmonary root in pigs.

In an experimental study in pigs, the function of monocuspid and bicuspid patches was compared to improve surgical reconstruction of a hypoplastic pulmonary root. Segments from glutaraldehyde-treated porcine aortic roots served as monocuspid and bicuspid patches. Their leaflets and commissures were marked with radiopaque metal clips. Marker movements were recorded at 100 frames/sec. Quantification of pulmonary insufficiency, right ventricular stroke volume, as well as pressures in the right ventricle, pulmonary artery, and aorta was performed before and after patch plasty. The cyclic motion of the leaflets showed a three-phase pattern in monocuspid and bicuspid patches: (1) a rapid opening motion with a significantly longer distance to be covered in monocuspid patches (7.5 mm in monocuspid versus 4.9 mm in bicuspid patches); (2) a slow closing motion that was significantly greater in monocuspid patches (31.5% of maximal displacement in monocuspid versus 18.2% and 23.8% in bicuspid patches); (3) a similar rapid closure motion in both types of patches. The commissural expansion was less than 6% for monocuspid and bicuspid patches and began 10 to 20 msec before valve opening. Considerable irregularities in the movement of the different leaflet markers, especially in monocuspid patches, indicated leaflet buckling as a result of redundant leaflet tissue. There was a significant pulmonary regurgitant fraction only in monocuspid patches (19% in monocuspid versus 7% in bicuspid patches) that occurred during early diastole. No pressure gradients were observed across either type of patch. In monocuspid patches, a greater leaflet displacement during rapid closure was correlated with an increased pulmonary insufficiency (r = 0.8875). In conclusion, the function of a bicuspid patch is superior to that of a monocuspid patch for repair of a hypoplastic pulmonary root and allows the construction of a competent and stenosis-free valve mechanism.

Animals↗
PubMed1992

Performance of a stentless xenograft aortic bioprosthesis up to four years after implantation.

Conventional biologic and mechanical prostheses have important limitations with regard to their hemodynamic characteristics and long-term durability. We evaluated the hemodynamic function of a stentless porcine aortic prosthesis in 10 patients by invasive pressure measurements and angiography with videodensitometry 8 +/- 4 days after operation, as well as by Doppler echocardiography 35 +/- 15 months after valve replacement. The early postoperative invasive study revealed a mean gradient of 8 +/- 6 mm Hg across the prosthesis, no regurgitation in eight patients, and mild regurgitation, defined as less than 20% regurgitant fraction, in the remaining two patients. The late postoperative Doppler echocardiographic study revealed a mean gradient across the aortic prosthesis of 6 +/- 3 mm Hg, mean Doppler-derived valve orifice area of 1.8 +/- 0.6 cm2, and color Doppler flow velocity mapping suggested no regurgitation in eight patients and mild regurgitation in two patients corresponding to early postoperative angiography. None of the 10 patients received anticoagulation therapy. The clinical course of all patients was without incident. This stentless aortic bioprosthesis may offer hemodynamic advantage; however, further studies are needed to allow comparison with conventional mechanical and biologic prostheses.

Adult↗
PubMed1991

Determination of cardiac ejection and valvular regurgitant fraction by on-line digital densitometry--methodology, validation, and application.

Videodensitometry allows to obtain both left and right ventricular ejection fraction (EF) and aortic or pulmonary regurgitant fraction (RGF) from the wash-out curve of contrast medium. We developed this technique to digital densitometry and integrated it in the standard digital image acquisition system 'Digitron' using Siemens user's library. Sources of error like scatter radiation, veiling glare, accumulation of iodine in tissue, and inhomogeneous contrast mixing were considered by using ECG gated image subtraction, background reference regions, data fit to ideal wash-out curves and calculation of EF and RGF exclusively from density differences. The method was validated by phantom studies in which simulated angiocardiograms were generated with given values of EF (50 to 70%) and RGF (0 to 45%). The results tended to overestimate RGF by up to 10 percent points, when image contrast was high and the ventricle was masked poorly by the lead shutters. In the clinical setting, the reliability of the results can be judged from the fit of the wash-out curve presented automatically on the screen on a semi-logarithmic scale. The technique is available to the physician in the catheterization laboratory on-line during or immediately after the examination, which facilitates routine use.

Absorptiometry, Photon↗
PubMed1988

Comparison of digital with conventional ventriculography for quantitative right ventricular studies.

To assess the feasibility of quantitative central venous digital angiocardiography, right ventricular spatial orientation, size, and shape were compared with measurements based on conventional angiocardiography, both obtained during routine cardiac catheterization in 21 children with various congenital heart defects. Without systematic error, correlations for end-diastolic and end-systolic volumes were excellent, at r = 0.986 and 0.969, respectively. Ejection fractions were similarly closely correlated. Premature ventricular contractions were common in conventional angiocardiography and absent in digital and angiocardiography. The amount of contrast medium was 36% of that used for conventional angiocardiography. Digital angiocardiography using reduced amounts of contrast medium given through a central venous catheter allows accurate assessment of right ventricular size and function.

Adolescent↗
PubMed1988

Up to 9 years of follow-up after anatomic correction of simple transposition of the great arteries.

For a continued assessment of the two-stage anatomic correction, we have evaluated the postoperative results in terms of clinical status, ECG, ventricular function, aortic root size and stiffness for up to 9 years in all 18 survivors. Weight and height were normal, the ECG was normal except for complete (n = 3) and incomplete (n = 11) right bundle branch block and supraventricular tachyarrhythmias post Blalock-Hanlon septectomy (n = 1) and p-wave abnormalities (n = 6). The pressures and ejection fraction of the left and right ventricles were within normal limits. The end-diastolic and endsystolic left ventricular volume and the muscle volume index were elevated. Six of 17 patients were outside the normal range of the left ventricular ejection fraction-endsystolic stress relationship. The diameter of the aortic root was larger than normal in all patients. There was a relation between the size of the patients at banding and the stiffness of the aortic root after anatomic correction. Patients with simple transposition of the great arteries up to 9 years after anatomic correction develop normally without atrio-ventricular conduction delay, arrhythmias or signs of coronary and myocardial insufficiency. The stiff and enlarged aortic roots do not seem to dilate. The reasons for the elevated left ventricular volumes and muscle volume indices are not clear at present. Primary anatomic correction may prevent these abnormalities.

Aorta↗
PubMed1987

Verapamil-induced ventricular tachycardia in hypertrophic cardiomyopathy.

A 17-year old boy with hypertrophic obstructive cardiomyopathy (HOCM) developed repeated short runs of self terminating ventricular tachycardia 12 hours after starting oral verapamil, which was substituted for propranolol therapy. It is suggested that alterations in sympathetic tone induced by changing from a beta-blocker to a calcium antagonist might have increased myocardial irritability thus favouring genesis of severe ventricular arrhythmias. Verapamil is often considered to be more effective than propranolol in the treatment of HOCM. However, if propranolol is replaced by verapamil one has to take account of the possibility of serious arrhythmias as demonstrated by our case.

Adolescent↗
PubMed1987

Cardiac hypertrophy in the developing heart.

To gain information on physiologic postnatal cardiac growth in humans and to characterize the left ventricle (LV) when subjected to various types of overload during that period, angiocardiographic volume parameters in infants, children, and adolescents were analyzed. In normal subjects, the relationships between end-diastolic volume (EDV), end-systolic volume (ESV), and stroke volume (SV) of the LV and right ventricle (RV), as well as the muscle volume (MV) of the LV and body surface area (BSA) were best fit by power functions with exponents of between 1.2 and 1.3. The EDV and ESV of the LV were smaller than those of the RV. Ejection Fraction (EF), muscle volume index (MVI = MV/EDV), and cardiac index (CI) were constant. In pressure loaded LVs, the MVI was elevated, and increased with increasing pressure load. The ESV tended to be smaller and EF tended to be higher than normal. There was no correlation between EF and EDV. In volume loaded LVs, MV was increased; the MVI, as well as the EF, was normal. The EDV and ESV were elevated without correlation between EF and EDV. In complete transposition of the great arteries. MVI diminished, increasing within months as a response to pressure underloading and overloading. In all groups, there was a negative correlation between EF and ESV, as well as between EF and the shape parameter elongation in systole. During postnatal growth, the normal heart grows overproportionally with respect to BSA, with the LV ejecting the same SV as the RV at a higher EDV and ESV. EF, MVI, and CI are age-independent parameters for assessment of cardiac function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Cardiac rhythm and conduction after two-stage anatomic correction of simple transposition of the great arteries.

To assess postoperative arrhythmias and AV-conduction defects associated with anatomic correction of simple transposition of the great arteries, 207 standard 12-lead surface and 43 24-hour electrocardiograms of all 17 patients followed after anatomic correction for up to 6.5 years were reviewed. No dysrhythmias or AV-conduction delays definitely attributable to anatomic correction were observed. One patient with a severe complex supraventricular tachyarrhythmia after a Blalock-Hanlon procedure has improved markedly, exhibiting respiratory AV-dissociation and 5 premature atrial complexes/minute 5 years after anatomic correction.

Arrhythmias, Cardiac↗
PubMed1986

Up to 7 years of follow-up after two-stage anatomic correction of simple transposition of the great arteries.

In 16 patients, constituting 100% of children followed for up to 7 years after two-stage anatomic correction of complete transposition of the great arteries, clinical and electrocardiographic data, as well as cardiac catheterization data in 12 patients, were analyzed. None of them has had signs or symptoms of coronary or myocardial insufficiency after an adaptation phase of 6 months after anatomic correction. Body weight normalized 3 to 6 months after anatomic correction, and was normal in most cases after 1 year. No atrioventricular conduction delays or arrhythmias definitely attributable to anatomic correction were observed. Peak systolic pressure in the right ventricle was slightly elevated in 10 of 12 patients studied due to residual pulmonary stenosis from the band site. End-diastolic and end-systolic volumes as well as ejection fraction and end-diastolic pressure of the right ventricle were normal. End-diastolic and end-systolic volumes of the left ventricle were elevated (p less than .01), while muscle volume, ejection fraction, and end-diastolic pressure were normal. The pulmonary root was distended during the banding stage and did not dilate as did the aortic root after anatomic correction. Patients with complete transposition of the great arteries up to 7 years after anatomic correction develop normally without atrioventricular conduction delays, arrhythmias, or signs of coronary and myocardial insufficiency. The enlarged aortic root does not seem to dilate. The reasons for elevated left ventricular volumes are not clear at the present time. Earlier operation may prevent these changes.

Body Weight↗
PubMed1985

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.

Age Factors↗