Quantitative perfusion imaging assessing acquired discrete peripheral pulmonary artery stenosis.

We present the case an 8-yr-old boy evaluated for anastomotic stenosis of the right pulmonary artery after surgical repair of hemitruncus at 6 wk of age. Pulmonary angiography revealed only mild narrowing and a 10-mm pressure gradient across the anastomosis, but quantitative perfusion imaging demonstrated that the right lung only received 16% of pulmonary blood flow. Subsequently, balloon angioplasty of the anastomotic site was performed, resulting in complete resolution of the stenosis and gradient. Early postangioplasty perfusion imaging demonstrated increased perfusion of the right lung to 35% of total pulmonary blood flow. It is theorized that initially a chronically hyperperfused lung may develop more capacious vessels and recruit new capillaries during the years of hyperperfusion such that a "perfect" angioplasty may result in less than symmetric perfusion. The inexpensive, noninvasive quantitative perfusion study is more sensitive and accurate in evaluating acquired (postsurgical) pulmonary artery stenoses.

Potentially serious drug interactions secondary to high-dose diltiazem used in the treatment of pulmonary hypertension.

Two patients had potentially serious drug interactions (phenytoin, digoxin) that were probably attributable to changes in pharmacokinetics and pharmacodynamics caused by high-dose calcium channel blocker therapy (diltiazem) in the treatment of pulmonary hypertension. Even in the approved normal dosages for the treatment of angina and hypertension, calcium channel blockers are known to cause significant changes in the metabolism of other drugs. Currently, no data exist on the effects of the very high dosages of these drugs, administered to patients with pulmonary hypertension, on the metabolism and clearance of other agents, although, based on our experience and literature reports, recommendations for monitoring therapy can be made.

Functional implications of the pulmonary microcirculation. An update.

The microscopic anatomy of the pulmonary circulation was reviewed, comparing the evidence for two competing models, the sheet-and-post paradigm and the tubular paradigm. Implications of the two paradigms were analyzed for function, including flow, recruitment, distension, and diffusion. We conclude that the pulmonary microcirculation is not essentially different from the systemic microcirculation except that two layers of tubular capillaries are arranged on a central layer of connective tissue, the alveolar wall. We find no morphologic basis or theoretic advantage for the sheet-and-post concept.

Surgical repair of anatomically corrected malposition of the great arteries.

Anatomically corrected malposition of the great arteries is a rare malformation in which the aorta and pulmonary artery arise from their appropriate ventricles but in an abnormal spatial relationship. This report describes 2 patients with anatomically corrected malposition who underwent closure of a ventricular septal defect and placement of a right ventricle-pulmonary artery conduit. A review of the literature indicates that surgical results have been good (92% survival) in those patients with situs solitus and atrioventricular concordance [S,D,L]. However, when there is atrioventricular discordance, that is, [S,L,D] or [I,D,L], hypoplastic right heart structures, or both conditions, the outcome after palliative procedures has been poor (29% survival). The results of surgical treatment should improve as this entity is recognized earlier and prompt surgical treatment is undertaken.

Doppler pressure gradient estimation in children. Accuracy, effect of activity and exercise, and the need for sedation during examination.

Noninvasive estimation of pressure drop has been shown to be an accurate and useful application of Doppler echocardiography. Most accuracy series have used patient-sedated catheterization gradient measurements as the standard of reference. Doppler gradient estimates, however, are commonly made without sedation of the patient when hemodynamics may differ from those present at catheterization. We questioned whether "unsedated" Doppler gradient estimates would correlate in a useful way with "sedated" catheter measurements, Doppler gradient estimates would vary with patient activity, exercise or crying, and Doppler gradient estimates made using chloral hydrate sedation would prove useful in predicting sedated catheter measurements. Twenty-five infants and children were examined under conditions 1 and 2 above, and 20 under condition 3. Sedated Doppler estimates, performed at the time of catheterization corresponded closely with catheter measurements (r = 0.97, SEE = 4.8), confirming the accuracy of the Doppler method. Gradients estimated by Doppler without sedation, or with activity, correlated poorly with sedated catheter measurements (SEE = 16.2, SEE = 34.9, respectively). Use of chloral hydrate sedation for Doppler estimates resulted in good correlation with subsequent sedated catheter measurements. The results demonstrate marked increases in noninvasive Doppler pressure gradient estimates under conditions other than sedation. Clinicians tend to think in terms of sedated catheter gradients as the standard of reference for evaluation of severity and need for surgery. Ultrasonic data can only be used if Doppler estimates are performed under similar physiologic conditions; in children this requires sedation.

Tetralogy of Fallot: selective staged management.

One hundred twenty-four patients with tetralogy of Fallot have undergone either primary total repair (61), shunt and later repair (30), or an initial shunt (33). The mean ratio of pulmonary anulus to descending thoracic aorta increased from 0.80 +/- 0.25 before the shunt to 1.22 +/- 0.26 before the repair (p less than 0.0001). The mean ratio in the primary repair group was 1.23 +/- 0.25. A transannular patch was necessary in only six of 91 patients (6.6%). Postrepair right ventricular/left ventricular pressure ratio averaged 0.50 +/- 0.11 in the shunt plus repair group and 0.43 +/- 0.12 in the primary repair group. Only four patients had a right ventricular/left ventricular pressure ratio less than 0.65. A significant inverse linear relationship existed between this ratio and the pulmonary anulus size measured at operation and normalized for the patient's height (p less than 0.01). Postoperative complications occurred in 21% of patients after a shunt and 20% of patients after open heart repair. The early mortality was 0.8% (1/124). An initial shunt in patients with a small pulmonary anulus can result in an increased anulus size and better hemodynamic result with frequent avoidance of a transannular patch. Staged repair may result in improved overall mortality rates.

Noninvasive estimation of peak pulmonary artery pressure by M-mode echocardiography.

In an attempt to predict peak pulmonary artery pressure from routine M-mode echocardiographic tracings, 95 infants and children with congenital heart disease were examined. Following the Burstin method for prediction of peak pulmonary artery pressure, which was originally based on the phonocardiogram and jugular phlebogram, M-mode echocardiography was used to measure the interval from pulmonary valve closure to tricuspid valve opening, namely, the period of isovolumic diastole. The measured interval was plotted on a modified table relating the interval, heart rate and predicted peak pulmonary artery pressure. The peak pulmonary artery pressure predicted by echocardiography was compared with that measured at cardiac catheterization. The correlation between predicted and actual peak pulmonary artery pressure was good (r = 0.86) for routine studies with the patient in the nonsedated state. All patients with a predicted peak pressure less than 40 mm Hg were found at catheterization to have a pressure less than 40 mm Hg. The correlation was better (r = 0.96) when comparing predictions made from the echocardiogram obtained while the patient was sedated for catheterization. Prediction of the magnitude of elevation of peak pressure was especially good when prediction and measurement were nearly simultaneous. Predictions were less accurate in the presence of tachycardia at rates of more than 155 beats/min. The method for estimating peak pulmonary artery pressure from M-mode echocardiographic tracings is reliable, relatively simple and clinically useful.

Hemodynamic effects of ketamine in children with congenital heart disease.

Pulmonary and systemic vascular responses to ketamine (2 mg X kg-1, intravenously) were studied during cardiac catheterization in 20 children with congenital heart lesions. Pulmonary and systemic resistances (Rp, Rs), ratios between pulmonary and systemic flows (Qp/Qs), and left to right (L----R) and right to left shunts (R----L) were calculated before and after ketamine administration. Statistically significant (P less than 0.05) but clinically minor increases in heart rate (106.8 to 109.9 beats/min), mean pulmonary artery pressure (20.6 to 22.8 mm Hg), and Rp/Rs (0.12 to 0.14) were seen after ketamine. There were no significant changes in systemic arterial pressure, Rs, Qp/Qs, L----R, R----L, or arterial oxygen or carbon dioxide tensions. No patient had any major untoward effects from ketamine administration. It is concluded that the hemodynamic alterations after ketamine administration in children undergoing cardiac catheterization are small and do not alter the clinical status of the patients or the information obtained by cardiac catheterization.

Pulsed Doppler echocardiographic evaluation of ventricular septal defect patches.

Doppler echocardiography has been shown to have high sensitivity and specificity for noninvasive detection of the flow disturbance of ventricular septal defect. After surgery for ventricular septal defect, one might expect loss of the ventricular septal defect flow disturbance. We used two-dimensional and pulsed Doppler echocardiography to evaluate 30 children undergoing surgery for ventricular septal defect to determine postoperative Doppler findings and the effect of ventricular septal defect patch material on those findings. Twenty-one patients had Dacron patches and nine pericardial patches. Doppler examinations were performed immediately after surgery and at intervals thereafter. The patches were imaged on two-dimensional echocardiograms and the Doppler method was used to evaluate flow at the patches. Doppler echocardiography was also used to estimate volume flow in the aorta and pulmonary artery to estimate postoperative ratio of pulmonary to systemic flow (Qp/Qs). Immediately after surgery 93% of patients had a flow disturbance detected by Doppler echocardiography in the region of the surgically placed patch. On postoperative day 1, 62% of Dacron-patched defects and 66% of pericardial patched defects showed evidence of residual shunting on Doppler examination. By the third postoperative day, this prevalence fell to 23% and 44%, respectively. By 2 weeks after surgery there was evidence of residual shunting in only two patients. In 26 of 30 early postoperative Qp/Qs estimates were under 1.6/1; all but two of these lost the Doppler-detected flow disturbance by 2 weeks after surgery. In three of 30 Qp/Qs estimates exceeded 1.9/1; two of these three required reoperation.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriohepatic dysplasia: phenotypic features and family studies.

Arteriohepatic dysplasia (AHD) is a disorder characterized by intrahepatic cholestasis and peripheral pulmonary artery stenosis. We have reviewed the phenotypic features in the 56 previously reported cases and 7 persons from our institutions with AHD to summarize the type of cardiac, hepatic, facial, ocular and skeletal manifestations observed in this disorder. Family studies evaluating first-degree relatives of patients with AHD are compatible with an autosomal dominant mode of inheritance with reduced penetrance and variable expressivity.

Noninvasive determination of pressure gradients in children: two methods employing pulsed Doppler echocardiography.

Pulsed Doppler echocardiography has been considered poorly suited for high velocity blood flow measurement, because of the problem of signal aliasing. Two methods for reduction of aliasing in a pulsed system were evaluated in an attempt to measure flow velocities characteristic of significant pressure gradients. With the angle correction method, carrier frequency, pulse repetition frequency and intercept angle were manipulated using a commercially available two-dimensional pulsed Doppler system. Forty children undergoing cardiac catheterization were studied. Gradients of 60 to 70 mm Hg were accurately predicted by this method, and gradients above 90 mm Hg were underestimated. Overall correlation (r) value was 0.95. The method is limited primarily by the introduction of potential error in measurement of intercept angle; it is advantageous in that it can be attempted using currently available pulsed Doppler echographic systems. With the multiple sample volume method, pulse repetition frequency was increased through the addition of extra sample volumes. Carrier frequency was minimized and angle correction was not employed. Thirty-nine children underwent cardiac catheterization using a prototype instrument. Excellent agreement between Doppler predictions and actual gradients was found for gradients up to 100 mm Hg (r = 0.99). Although this method requires new instrumentation, it is advantageous in that gradients are accurately predicted and cannot be overestimated. Both methods retain the advantages of pulsed Doppler study for comprehensive flow evaluation and reference their quantitative application within a two-dimensional echographic format. Neither method is simple, and each has been validated only in pediatric subjects.

Noninvasive evaluation of Blalock-Taussig shunts: determination of patency and differentiation from patent ductus arteriosus by doppler echocardiography.

Pulsed Doppler echocardiography has been used to detect continuous turbulent flow in the right pulmonary artery after Blalock-Taussig shunts. Since continuous turbulent flow could also arise from patent ductus arteriosus (frequently present in the neonate), continuous turbulent flow in the right pulmonary artery is not specific for Blalock-Taussig shunt function. We evaluated 35 Blalock-Taussig shunts from suprasternal or high parasternal approach for flow in the right pulmonary artery, and in the Blalock-Taussig shunts themselves. From precordial approach, Doppler evaluations of the main pulmonary artery were also made in search of flow characteristic of patent ductus arteriosus. Doppler detection of flow within the Blalock-Taussig shunts indicated shunt patency, and indicated that continuous turbulent flow in the right pulmonary artery was not due to only patent ductus arteriosus. Shunts were proven patent in 31 patients, occluded in four. Twelve patients also had patent ductus arteriosus. By Doppler, the right pulmonary artery had continuous turbulent flow in 30 of 31 patients in whom the right pulmonary artery was found. From the suprasternal or high parasternal approach, the right Blalock-Taussig shunts were detected by marked continuous turbulent flow directed away from the transducer, between the aortic and superior vena caval flow signals. Left Blalock-Taussig shunts had similar directional continuous turbulent flow. Prosthetic shunts were identified by the dense shunt material. Twenty-four of 31 functional shunts were identified, and all contained continuous turbulent flow. Three left-sided shunts were missed. All four occluded shunts were identified by Doppler, and had no lumen flow within.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary microcirculation: tubules rather than sheet and post.

We examined latex casts of the pulmonary microcirculation with the scanning electron microscope (SEM). Mature rats were anesthetized and ventilated; the pulmonary vasculature was washed out with lactated Ringer solution and then filled with a mixture of Geon latexes. The airways were filled with glutaraldehyde with resulting transmural vascular pressures of 10 cmH2O. After critical-point drying and corrosive removal of the lung tissue, SEM studies of the vascular replicas revealed two distinct patterns of pulmonary microcirculation: 1) sparse, long, tubular capillaries that comprise the thin subpleural layer and appear as "filler" in the peribronchial spaces; and 2) alveolar microcirculation that is composed of tightly matted, intersecting tubules, shorter but of the same diameter as type 1, in spherical array in two layers. The alveolar capillaries at low magnification appear superficially as sheets; however, the detailed morphology is not consistent with the sheet-and-post model. We conclude that the basic component of the pulmonary microcirculation is tubular and not different from other capillary beds except in density.

Left ventricular performance in endotoxin shock in dogs.

Endotoxin shock, with maximal velocity of contraction (Vmax) as our index of contractility, showed no myocardial depression in an earlier 4-h study (Guntheroth, Proc. Soc. Exp. Biol. Med. 157: 610--614, 1978). Because of reports of late deterioration, we studied six dogs until spontaneous death (9--18 h). Heart rate nearly doubled and left ventricular filling pressure and aortic mean pressure fell, but Vmax did not change significantly. Because of concern that the marked increase in heart rate may have contributed to an artifactual maintenance of Vmax (due to its frequency dependence, inherent in dp/dt), we studied a final group of five dogs with three additional indicators of contractility. End-systolic pressure-diameter ratio (Emax), ejection fraction (sonar-determined from the minor axis of the left ventricle), and frequency-normalized average rate of generation of power density (FARPD) all fell early and remained low until death. We conclude that myocardial contractility is significantly reduced in endotoxin shock, early and sustained. Its presence is masked somewhat in the untreated subject by the reduced work load, secondary to hypovolemia.

Prognosis in primary ventricular tachycardia in the pediatric patient.

Five male pediatric patients with primary ventricular tachycardia are described. Although three were initially in congestive heart failure due to the tachycardia and were extremely difficult to manage, all have completely recovered, are not taking medication, and are free of arrhythmia. Three of the patients required long-term management with quinidine, with a therapeutic goal of controlling the heart rather than abolishing the arrhythmia. No growth disturbances were found in those three patients. A review of reported cases revealed 71 infants and children with ventricular tachycardia not associated with heart disease or systemic disorders; only four deaths were reported (5.6%). In the primary form of ventricular tachycardia in children, complete pharmacologic suppression may not be achieved without seriously endangering the normal electrophysiologic functions. Controlling the rate to an asymptomatic level with pharmacologic means is safer for a problem that may be self-limited.

Evaluation of ejection murmurs by pulsed Doppler echocardiography.

A common problem is a soft basal ejection murmur in an asymptomatic child with a normal electrocardiogram and chest x-ray films. If the diagnosis is aortic stenosis, there is a need for prophylaxis for subacute bacterial endocarditis and concern about development of calcific aortic stenosis. In 40 consecutive children referred for this differential diagnosis, aortic stenosis was diagnosed in 30, based on an ejection murmur at the second right interspace (not necessarily louder than at the second left), which transmitted well to the neck, accompanied by a normal second heart sound. Pulsed Doppler echocardiography confirmed turbulence at the aortic valve in 26. In the 10 children diagnosed clinically as having an innocent murmur, three had evidence on pulsed Doppler echocardiography for an abnormal aortic valve. The conventional echocardiographic findings of an eccentric aortic orifice were present in only 21 of 29 patients with aortic turbulence. Though our current clinical criteria are reasonably specific (87%), they are not as sensitive (70%). Pulsed Doppler echocardiography provides powerful non-invasive assistance for this important differential diagnosis.

The role of respiratory infection in intrathoracic petechiae. Implications for sudden infant death.

Intrathoracic petechiae are characteristic of the postmortem changes found in sudden infant death syndrome. The presence and distribution of these petechiae have been claimed as evidence for airway obstruction as the mechanism of death. In a group of young, mature rats that were free of infection, hypoxic asphyxia produced an insignificant number of petechiae, whereas in all littermates infected with an enzootic virus (Sendai) large numbers of petechiae with hypoxic asphyxia developed. Rats similarly infected, but killed with an overdose of pentobarbital sodium, had no petechiae. Most importantly, infected rats with unremitting airway obstruction were free of petechiae. Thus, the experimental conditions necessary for the presence of intrathoracic petechiae are profound hypoxia and infection, with persistent circulation and respiratory effort; persistent airway obstruction does not produce petechiae, with or without infection.

Pulsed Doppler echocardiographic diagnosis of patent ductus arteriosus: sensitivity, specificity, limitations, and technical features.

To determine the diagnostic features, sensitivity, and specificity of pulsed Doppler echocardiographic (PDE) diagnosis of patent ductus arteriosus (PDA), 110 infants with heart disease were examined by PDE from the precordial and suprasternal notch approaches. On precordial examination, PDA was diagnosed upon recording of diastolic ductal flow into the pulmonary artery. From the suprasternal approach, PDA was suspected upon recording of continuous turbulent flow in the right pulmonary artery. A PDA was proved by invasive means in 45 of 110 cases. Precordial PDE had diagnosed PDA in 43 of 45 cases. In eight of 110, continuous turbulent flow was present in the pulmonary artery from the precordial approach, but no PDA jet was recorded. In two of eight, PDA was present, and in six of eight others systemic-to-pulmonic communications were present. Precordial PDE diagnosis of PDA had a sensitivity of 96%, specificity of 100%, positive predictive index of 100%, and negative predictive index of 97%. From the suprasternal notch approach, PDA was suspected in 51 cases, with six false-positive diagnoses, yielding a sensitivity of 100%, specificity of 91%, positive predictive index of 88%, and negative predictive index of 100%. Since the diastolic ductal jet flowing into the pulmonary artery was specific for PDA in all patients in whom it was recorded from a precordial approach, that approach and diagnostic feature, with sensitivity and positive predictive index of 100%, would seem preferred for PDE diagnosis of PDA. This would be especially important if the PDE diagnosis of PDA were to be used in place of invasive documentation of PDA, and in the differential diagnosis of PDA and other systemic-to-pulmonic communications. The suprasternal approach, while not specific for PDA, may have the advantage of sensitive detection or exclusion of a variety of systemic-to-pulmonic communications.