M. Bourgeois

Characteristics of Aortic Diastolic Pressure Decay with Application to the Continuous Monitoring of Changes in Peripheral Vascular Resistance

Large changes in stroke volume and peripheral vascular resistance were induced by varying the heart rate and by intra-aortically infusing acetylcholine or angiotensin II in six dogs with heart block and electromagnetic flowmeters chronically implanted around their ascending aortas. Changes in stroke volume, aortic and atrial pressures, and systemic resistance were monitored continuously for 3–6 hours under morphine-pentobarbital anesthesia. The characteristics of diastolic pressure decay at heart rates ranging from 60 beats/min to 200 beats/min and during transient periods of asystole were studied, especially with reference to the distortions caused by reflected pressure waves. The diastolic phase of pressure pulses recorded over a segment of the thoracic aorta several centimeters long centered about 4 cm cephalad to the dorsal insertion of the diaphragm could be closely approximated by a straight line on a semilogarithmic scale. Under the conditions of these experiments, changes in the slope of that line and of its reciprocal, the time constant, correlated well with concomitant variations in peripheral vascular resistance. This relationship appears to be of practical value for continuous monitoring of systemic resistance directly from the diastolic segments of pressure pulses recorded from the lower thoracic aorta.

Left ventricular diastolic dysfunction late after coarctation repair in childhood: Influence of left ventricular hypertrophy

OBJECTIVES Left ventricular systolic and diastolic function were evaluated late after successful operation for aortic coarctation in childhood. BACKGROUND Persistent arterial hypertension and left ventricular hypertrophy after coarctation repair might impair left ventricular function. METHODS Biplane angiography and simultaneous high fidelity pressure measurements were performed in 12 patients 3 to 12 years postoperatively (residual pressure gradient 4 mm Hg). Eight patients were normotensive and four had borderline hypertension. Data at rest and after nitroprusside infusion (1.7 micrograms/kg per min) were evaluated and compared with data from 12 control subjects. RESULTS Systolic left ventricular function (ejection fraction-end-systolic wall stress relation) was normal in all patients. However, left ventricular muscle mass (113 vs. 86 g/m2), right atrial pressure (5.2 vs. 1.9 mm Hg) and left ventricular end-diastolic pressure (16 vs. 11 mm Hg) were significantly higher in patients than in control subjects. There was a linear relation between muscle mass and left ventricular end-diastolic (r = 0.66, p < 0.001) or right atrial (r = 0.60, p < 0.01) pressure. Left ventricular relaxation and myocardial stiffness were normal. However, there was an upward shift of the diastolic pressure-volume curve when compared with control values, but this shift was reversed by the administration of nitroprusside. CONCLUSIONS Systolic function is normal late after coarctation repair. However, diastolic function can be abnormal with an upward shift of the diastolic pressure-volume curve that is reversed by nitroprusside administration and is probably due to residual left ventricular hypertrophy.

Volumetric analysis of the right ventricle in children with congenital heart defects: comparison of biplane angiography and transthoracic 3-dimensional echocardiography.

BACKGROUND Three-dimensional echocardiography is a non-invasive imaging technique. The fact that it permits volumetric analyses independently of geometrical assumptions makes it a putatively useful method for the precise measurement of the volumes of the irregularly shaped right ventricles in children. The aim of this study was to assess the feasibility of this method and its agreement with angiocardiography based estimates of right ventricular volume in children with congenital heart disease. METHODS We studied 102 children with congenital heart disease. The angiocardiographic right ventricular volumetry was performed using a biplanar technique using Simpsons rule and corrected with Langes correction factors. The echo data sets were registered trans-thoracically with a rotating transmitter. Volumes were calculated after manual planimetry by adding the volumes of the individual slices. RESULTS Calculation of right ventricular volume echocardiographically was possible only in 34% of patients, mostly infants and toddlers. In comparison to angiocardiography, the measured volumes were 1.1 +/- 6.9 ml (19.5 +/- 34.1%) or 6.3 +/- 9.4 ml (42.5 +/- 33.6%) smaller during systole or diastole, respectively. The limits of agreement were -12.5 and 13.6 ml, or 12.45 and 25.15 ml during systole or diastole, respectively. When plotted to a logarithmical scale, the correlation coefficients r2 were 0.70 for systolic and 0.79 for diastolic measurements. CONCLUSION Transthoracic 3-dimensional echocardiography with a rotating transmitter is feasible for volumetry only in small children. The volumes measured were significantly smaller than the ones calculated from the angiocardiographic images. The correlation between the two methods is moderate.

Volume Measurement of the Left Ventricle in Children with Congenital Heart Defects: 3-Dimensional Echocardiography versus Angiocardiography

Background: Volume measurement of the left ventricle is currently done by 2-dimensional echocardiography or angiocardiography. However, for the calculation of volumes by these methods, geometrical assumptions must be made. For a precise ventricular volumetry, independent of mathematical assumptions, imaging techniques as the 3-dimensional echocardiography (3D-echo) are required, which permit the imaging of the real ventricular shape. The aim of the study was therefore to detect, whether 3D-echocardiography is suitable for left ventricular volumetry in children with congenital heart disease and whether the 3D-echocadiographically measured volumes correlate sufficiently well with angiocardiographically measured left ventricular volumes. Methods: 102 children with congenital heart disease were investigated. For angiocardiographic left ventricular volume measurement Simpson’s rule was used. Results were corrected with Lange’s correction factors. The 3D-echo data sets were registered with a rotating transthoracic transducer. Ventricular volumes were calculated after manual planimetry by summation of the volumes of the single slices. Results: The left ventricular volume could be calculated by 3D-echo in 83% of patients of all ages. In comparison to angiocardiography, the measured volumes were 0.6 ± 3.3 ml (0.9 ± 25.8%) or 7.1 ± 28.4 ml (7.4 ± 12.1%) smaller during systole or diastole, respectively. The correlation coefficients r2 were 0.89 for systolic and 0.93 for diastolic measurements after logarithmic transformation. Pressure or volume overload did not influence significantly the difference between the two methods. Conclusion: Transthoracic 3D-echocardiography with a rotating transmitter is feasible for volumetry of the left ventricle in most children. The volumes measured by 3D-echo were significantly smaller than those calculated from the angiocardiography by Simpson’s rule. The measurements were not influenced by the kind of load of the ventricle. The correlation between the two methods is good.

Left ventricular thrombus in a 2-year-old boy with cardiomyopathy: Lysis with recombinant tissue-type plasminogen activator

A 2-year-old boy with cardiomyopathy and clinical signs of cardiac failure presented with an echodense structure in the left ventricle. This structure was seen from different echocardiographic views adjacent to a hypokinetic area of the apex and lateral free wall. It was different in texture and motion from the underlying myocardium and thus met the diagnostic criteria of a left ventricular thrombus. This thrombus protruded into the cavum and was partly mobile. In view of a high embolic risk, thrombolytic therapy with recombinant tissue plasminogen activator was started. The thrombus resolved within 72 h without any embolic or bleeding complications. No recurrence of the thrombus was observed during a 3-month follow up period.

Hypertrophic non-obstructive cardiomyopathy caused by disorder of the myofiber texture.

A case of hypertrophic non-obstructive cardiomyopathy caused by a disorder of the myofiber texture was observed in a 10 year old boy. The heart weighed 390 g and showed concentric hypertrophy of the left and right ventricles as well as of the ventricular septum. Additional findings consisted in an abnormal septum membranaceum and a accessory tricuspid valve leaflet. Severe cardic hypertrophy was associated with prominent interstitial and subendocardial fibrosis, and pronounced intimal fibrosis of the intramural arteries. Electron microscopy revealed various degrees and stages of hypertrophy of the myocardial cells combined with severe degenerative changes. Additional changes of the sinus node and conduction system were responsible for a tachycardia-bradycardia syndrome, complete left bundle branch block and final total AV-block.

Anomalous Origin of All Coronary Arteries from the Pulmonary Trunk

The origin of both coronary arteries from the pulmonary artery is a rare cardiac malformation. We report a baby who presented with an echocardiographically diagnosed perimembranous ventricular septal defect and normal left ventricular (LV) function. Later on the boy developed failure to thrive and increasing tachypnea. At the age of 5 weeks the ECG showed that LV strain and echocardiographic LV function had worsened (FS 18%). Echocardiography and heart catheterization showed that all coronary arteries originated from the pulmonary trunk. Intraoperative inspection revealed a single ostium for the right and left coronary artery in the nonfacing sinus of the pulmonary trunk. A tube was constructed connecting the coronary artery to the ascending aorta. Coronary perfusion was sufficient and the sinus rhythm was restored. However, in the early postoperative period there was a sudden deterioration of cardiac output followed by cardiac arrest. Reanimation was not successful.

Complete AV-block in two children with immunohistological proven myocarditis

We report two children with acquired third degree AV-block caused by acute myocarditis. The diagnosis was proven by endomyocardial biopsy. Severe lymphocytic myocardial infiltration was shown using immunohistological methods. One of the children was treated with prednisone. During therapy conduction disturbance nearly disappeared and infiltration was markedly reduced in a subsequent biopsy. In the other patient the parents refused immunosuppressive treatment and a permanent pacemaker was necessary for persistent bradycardia.

Balloon valvoplasty in infants with tetralogy of Fallot: effects on oxygen saturation and growth of the pulmonary arteries.

Balloon valvoplasty was undertaken in 27 patients with tetralogy of Fallot for first-stage palliation. Indications were arterial saturation of oxygen < 80%, hypoxic spells and duct-dependant pulmonary perfusion. The dilation was performed following diagnostic heart catheterization. Saturations improved from 75% +/- 8.5 before valvoplasty to 85% +/- 8.4 after the procedure, and worsened little to 83% +/- 9.6 at follow-up after 3.4 months. The pulmonary valvar orifice was hypoplastic in most patients (Z = -3.3 +/- 1.2), and did not change after the procedure. The cross-sectional area of the pulmonary arteries was diminished initially, reflected by a Nakata index of 186 +/- 95 mm2/m2. After valvoplasty, we found widening of the vessels (Nakata index 225 +/- 100 mm2/m2). At follow-up no further growth of the arteries was observed (Nakata index 209 +/- 109 mm2/m2). The procedure was complicated by hypoxic spells in three patients which were controlled by intravenous propranolol, and deep venous thrombosis in four patients. Our data demonstrate that balloon valvoplasty is feasible for initial palliation in patients with tetralogy of Fallot. It does not, however, produce growth of the pulmonary arteries or of the pulmonary valve.

Prolapsed valve of the foramen ovale in newborns and infants with coarctation of the aorta.

SummaryOut of 60 newborns and infants with symptomatic coarctation of the aorta, 34 had a significant left-to-right shunt at atrial level. In 20 of these 34 children, the atrial shunt had disappeared after surgical correction of the coarctation. All patients with this “reversible” shunt, thought to be secondary to an incompetent valve of the foramen ovale, were younger than 35 days at first cardiac catheterization. Left atrial pressure and left atrial volume of these patients did not differ significantly from those in a control group without atrial shunt. The conditions necessary for the development of a valve-incompetent foramen ovale include not only an increased left ventricular work load, but also a thin and pliable valve of the foramen ovale. It is only in infants younger than one month of age that the valve is thin and pliable enough to prolapse through the foramen ovale and form a channel between the two atria, which results in a left-to-right atrial shunt.