Pulmonary hypertension induced with an intra-arterial balloon: an alternate mechanism

The Laks catheter is a triple-lumen balloon catheter used to distend the canine main pulmonary artery while recording right ventricular pressure and the arterial pressure distal to the balloon. A rise in arterial pressure reported to occur during distension has been attributed to vasoconstriction rather than passive obstruction by the balloon. We tested this in six anesthetized dogs by inflating the Laks catheter-balloon while recording pressure distal to the balloon from the Laks catheter as well as from additional catheters in right and left pulmonary arteries placed retrogradely through lobar branches following thoracotomy. We found that balloon inflation increased pressures in the arterial port of the Laks catheter and in the left pulmonary artery catheter but reduced it in the right pulmonary artery. Tightening a snare around the right pulmonary artery had the same effects on pressures. Similar results were obtained while cardiac output was controlled by left ventricular bypass perfusion in four dogs. We conclude that the Laks catheter-balloon obstructs flow to the right lung and that the arterial pressure rise recorded in it during balloon inflation cannot be distinguished from that caused by occlusion of the right pulmonary artery.     

Arousal response to upper airway obstruction in young lambs: comparison of nasal and tracheal occlusion

Experiments were done on seven lambs to determine if site of occlusion--nasal versus tracheal--influences the cardiopulmonary and arousal responses from sleep to upper airway obstruction. Each lamb was anesthetized and instrumented for sleep staging and measurements of heart rate and arterial hemoglobin oxygen saturation. A tracheostomy was also done and a fenestrated tracheostomy tube placed in the trachea. Prior to an experiment, A 5F balloon-tipped catheter was inserted through the decannulation cannula into the tracheostomy tube so that tracheal occlusions could be accomplished by inflating the balloon. In addition, a 5F balloon-tipped catheter was inserted into the inlet of a pre-formed silicone mask sealed to the animals snout with silicone rubber foam so that nasal occlusions could be accomplished by inflating the balloon. During an experiment, measurements were made in quiet sleep and in active sleep during control periods of tidal breathing and during experimental periods of nasal or tracheal occlusion. Upper airway obstruction was terminated by deflating the balloon once the animal aroused from sleep. Arousal occurred sooner following nasal occlusion than during tracheal occlusion in quiet sleep; 64 percent of arousals occurred within five seconds of nasal occlusion whereas only 14 percent of arousals occurred within five seconds of tracheal occlusion in quiet sleep. In addition, SaO2 and heart rate decreased more before arousal following tracheal occlusion than following nasal occlusion. However, there was not a significant effect of site of obstruction on time to arousal or the change in SaO2 before arousal in active sleep.(ABSTRACT TRUNCATED AT 250 WORDS)     

MENTAL health services

In the diagnosis of congenital heart disease, the cardiologist was formerly concerned with distinguishing the operable from the inoperable cases. With the development of "open" heart operations under hypothermia and extracorporeal circulation, the majority of congenital heart lesions have become correctable. It is now necessary to make an exact anatomic diagnosis preoperatively. The present discussion reviews the diagnostic methods employed by the cardiac team in investigating a patient with congenital heart disease.     

Effect of pulmonary blood flow on leukocyte uptake and release by dog lung

The effect of pulmonary blood flow on leukocyte uptake and release by the lung was examined in 10 anesthetized spontaneously breathing dogs. Pulmonary arterial and pulmonary venous blood was sampled with catheters placed into the right ventricle and aorta, respectively. Pulmonary blood flow was lowered by inflating a balloon catheter located in the inferior vena cava. In five experiments simultaneous blood samples were drawn from the right ventricle and aorta at 10-s intervals during a control period, a 2- to 3-min period of low flow, and a recovery period. In five additional experiments, less frequent samples were taken over periods of 15-60 min. Total leukocyte concentrations and differential counts were determined for each blood sample. The study shows that large numbers of leukocytes become sequestered within the lung when pulmonary blood flow is low and that an equivalent number of cells are released from the lung after deflation of the balloon catheter. Both the polymorphonuclear leukocytes and the lymphocytes were taken up by the lung when pulmonary blood flow was reduced. We conclude that pulmonary blood flow has a marked effect on the uptake and release of leukocytes by the dog lung.     

Focused force angioplasty: theory and application

Focused force angioplasty is a technique in which the forces resulting from inflating an angioplasty balloon in a stenosis are concentrated and focused at one or more locations within the stenosis. While the technique has been shown to be useful in resolving resistant stenoses, its real value may be in minimizing the vascular trauma associated with balloon angioplasty and subsequently improving the outcome.     

Vessels of the heart and lung in some experimental defects]

Under study were changes of intraorganic blood vessels of the heart and lungs in some experimental defects (open arterial defect, coarctation of the aorta, simultaneous existence of these two defects, stenosis of the pulmonary trunk, defect of the interatrial septum, triad of Fallot, syndrom of Lutembachet). Morphological data correlated with blood pressure in the pulmonary circulation and cardiac chambers. The complex of compensatory-adaptational mechanisms consisting of comparatively active and passive zones is formed in the heart and lungs. In most cases the changes develop in the vessels already existing. In hypertrophy of the myocardium when there is hypertension and hypervolemia in coronary vessels, sinusoids perform the function of blood reservoir, to a certain degree balancing the blood pressure, and luminar ducts relieve the muscle from excessive blood. The changes in the vascular system of the lung are directly dependent upon the pressure in the pulmonary circulation and the duration of observation. The closing arteries are the most active link in the chain of compensatory-adaptational mechanisms.     

Measurement of bronchial arterial blood flow and bronchovascular resistance in sheep

We studied the bronchial arterial blood flow (Qbr) and bronchial vascular resistance (BVR) in sheep prepared with carotid-bronchial artery shunt. Nine adult sheep were anesthetized, and through a left thoracotomy a heparinized Teflon-tipped Silastic catheter was introduced into the bronchial artery. The other end of the catheter was brought out through the chest wall and through a neck incision was introduced into the carotid artery. A reservoir filled with warm heparinized blood was connected to this shunt. The height of blood column in the reservoir was kept constant at 150 cm by adding more blood. Qbr was measured, after interrupting the carotid-bronchial artery flow, by the changes in the reservoir volume. The bronchial arterial back pressure (Pbr) was measured through the shunt when both carotid-bronchial artery and reservoir Qbr had been temporarily interrupted. The mean Qbr was 34.1 +/- 2.9 (SE) ml/min, Pbr = 17.5 +/- 3.3 cmH2O, BVR = 3.9 +/- 0.5 cmH2O X ml-1 X min, mean pulmonary arterial pressure = 21.5 +/- 3.6 cmH2O, and pulmonary capillary wedge pressure (Ppcw) = 14.3 +/- 3.7 cmH2O. We further studied the effect of increased left atrial pressure on these parameters by inflating a balloon in the left atrium. The left atrial balloon inflation increased Ppcw to 25.3 +/- 3.1 cmH2O, Qbr decreased to 21.8 +/- 2.4 ml/min (P less than 0.05), and BVR increased to 5.5 +/- 1.0 cmH2O.ml-1.min (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Interventional radiology in congenital and acquired cardiovascular diseases

The paper outlines the present-day achievements in interventional radiology in cardiovascular diseases: balloon valvuloplasty in cardiac diseases (isolated pulmonary arterial stenosis, aortic and mitral stenosis), balloon vasodilatation (peripheral pulmonary arterial stenosis, aortic coarctation), embolization of the vessels and pathological communications, atrioseptostomy, transcatheter closure of atrial septal defects.     

Roentgeno-functional studies in ectopia of the anal canal in children

Analysis of x-ray data on 70 pediatric patients aged one day-15 yrs, was performed. In 55 cases the investigation was conducted before the correction of ectopia of the anal canal, in 11 cases after the previously described operation for forming the anal orifice (FAO), in 4 cases there was stenosis of the anal orifice without ectopia. Radiograms performed during irrigoscopy and (or) with a Foley catheter were assessed. Weakening and then complete incompetence of the puborectal muscle, determining incontinence of feces, were shown to be proportional to age and a degree of stenosis of the colon orifice. A necessity of radical operation in the second half-year of the life or measures to ensure adequate bowel evacuation were shown.     

OPEN HEART OPERATIONS—Results in 100 Consecutive Cases,Using Extracorporeal Circulation

In one hundred consecutive cases in which operations were done on the heart with the surgical field exposed to view and circulation was shunted to extracorporeal apparatus, there were six deaths. None were attributable to the by-pass procedure. The lesions were of various kinds, congenital and acquired. In one case a fibromyxosarcoma that was obstructing the right ventricular outflow tract and invading the main pulmonary artery was successfully excised.     

Expiratory muscle activity during pulmonary edema in the anesthetized dog.

The present study evaluated the reflex response of the expiratory muscles to pulmonary congestion and edema. The electromyograms of two thoracic and four abdominal expiratory muscles were recorded in 12 anesthetized dogs. Pulmonary edema was induced by rapid saline infusion in six dogs and injection of oleic acid into the pulmonary circulation in the remaining six dogs. Both forms of pulmonary edema reduced pulmonary compliance, interfered with gas exchange, and induced a rapid and shallow breathing pattern. The electrical activity of all abdominal muscles was suppressed during both forms of pulmonary edema. In contrast, the electromyogram activity of the thoracic expiratory muscles was not significantly affected by pulmonary edema. Acute pulmonary arterial hypertension produced in two dogs by inflating a balloon in the left atrium had no effect on ventilation or expiratory muscle electrical activity. In two vagotomized dogs, pulmonary edema did not inhibit the expiratory muscles. We conclude that pulmonary edema suppresses abdominal but not thoracic expiratory muscle activity by vagal reflex pathway(s). Extravasation of fluid into the lung appears to be more important than an increase in pulmonary vascular pressure in eliciting this response.     

Congenital heart disease cyanotic children

Cyanosis is often the only apparent symptom of congenital heart disease for which a child is brought to a physician. Some of the more common anomalies can be diagnosed from this and other symptoms by a general practitioner. Squatting after exertion is a sign of tetralogy of Fallot; severe disability with relatively mild cyanosis may indicate pure pulmonary stenosis. A brisk, short, rasping systolic murmur is characteristic of these conditions and of tricuspid atresia. Tetralogy of Fallot is further symptomatized by a boot-shaped heart, not greatly enlarged, and right axis deviation on electrocardiograms. Typically the lung fields are clear. The author's treatment of choice is aortic-pulmonary or subclavian-pulmonary anastomosis as indicated, preferably done after the child is three years old if the condition is not so severe as to require earlier operation. Pure pulmonary stenosis, which in some cases cannot be distinguished from tetralogy of Fallot except by cardiac catheterization and angiocardiography, may in more typical cases be diagnosed by convexity rather than concavity in the pulmonary segment and by differences in electrocardiograms. An expanding valvulotome is used to open the stenosed pulmonary valve, which is then dilated.A systolic murmur, a round heart and left axis deviation are usually found in tricuspid atresia. Shunt operations performed for relief of this condition may lead to later heart failure because of the devious rerouting of blood through the heart. The operations here outlined and others are statistically evaluated.     

Pulmonary neutrophil kinetics in sheep: effects of altered hemodynamics

We investigated the effect of elevated left atrial pressure and reduced cardiac output on pulmonary neutrophil kinetics in the sheep. Sheep neutrophils were isolated, labeled with 111In-oxine, and reinfused. Erythrocytes were labeled with [99mTc]pertechnetate. A gamma camera measured the lung activities of the labeled neutrophils and erythrocytes. The results indicated that 38.5% of the total injected neutrophils marginated in the lung. Pulmonary hemodynamics were altered by inflating a left atrial balloon three times in each sheep for 15-30 min to achieve 5- to 25-mmHg increments in pulmonary arterial wedge pressure. At least a 30-min recovery period was allowed between inflations. After each left atrial balloon inflation, neutrophil uptake remained unchanged from base line, despite decreased mean cardiac output to 0.67 +/- 0.24 (+/- SD) 1/min and increased pulmonary blood volume. The absence of pulmonary neutrophil uptake was confirmed by arterial-venous measurements. Increased pulmonary blood volume had little effect on lung neutrophil uptake, suggesting that most of the pulmonary neutrophils are marginated. We conclude that the lungs have a large marginated neutrophil pool compared with the circulating pool and that reduced cardiac output and elevated left atrial pressure have no effect on pulmonary neutrophil kinetics in the sheep.     

CONGENITAL HEART DISEASE IN CYANOTIC CHILDREN

Cyanosis is often the only apparent symptom of congenital heart disease for which a child is brought to a physician. Some of the more common anomalies can be diagnosed from this and other symptoms by a general practitioner. Squatting after exertion is a sign of tetralogy of Fallot; severe disability with relatively mild cyanosis may indicate pure pulmonary stenosis. A brisk, short, rasping systolic murmur is characteristic of these conditions and of tricuspid atresia.Tetralogy of Fallot is further symptomatized by a boot-shaped heart, not greatly enlarged, and right axis deviation on electrocardiograms. Typically the lung fields are clear. The author''s treatment of choice is aortic-pulmonary or subclavian-pulmonary anastomosis as indicated, preferably done after the child is three years old if the condition is not so severe as to require earlier operation.Pure pulmonary stenosis, which in some cases cannot be distinguished from tetralogy of Fallot except by cardiac catheterization and angiocardiography, may in more typical cases be diagnosed by convexity rather than concavity in the pulmonary segment and by differences in electrocardiograms. An expanding valvulotome is used to open the stenosed pulmonary valve, which is then dilated.A systolic murmur, a round heart and left axis deviation are usually found in tricuspid atresia. Shunt operations performed for relief of this condition may lead to later heart failure because of the devious rerouting of blood through the heart.The operations here outlined and others are statistically evaluated.     

Pulmonary hypertension: the role of the electrocardiogram

A 54-year-old female was referred to our centre for further evaluation of recently established severe pulmonary hypertension. Six months prior to presentation to the cardiologist of the referring centre, the patient had first experienced exertional dyspnoea. At the time of presentation to the referring cardiologist, the patient’s ECG showed signs of an increased right heart load. Interestingly, this patient had undergone a thorough cardiac evaluation in the referring centre seven years before when she presented with severe hyperthyroidism. At that time there were no symptoms or signs of pulmonary hypertension on ECG, echocardiography, or at heart catheterisation. Thorough evaluation in cooperation with the referring centre demonstrated that this patient was suffering from idiopathic pulmonary arterial hypertension, a rare form of pulmonary hypertension. We conclude this report with a discussion on the potential use of the ECG for the diagnosis of increased right heart load. (Neth Heart J 2008;16:250-4.)     

Comparison of isogravimetric and venous occlusion capillary pressures in isolated dog lungs

Venous occlusion capillary pressures (Pcv) were simultaneously compared with isogravimetric capillary pressures (PcI) in the same isolated perfused dog lung preparations. For 26 determinations, PcI averaged 1.23 +/- 0.22 (SE) mmHg higher than Pcv. However, the two measurements of capillary pressure were highly correlated (r = 0.99), and the following regression equation was obtained: Pcv = 1.12 PcI - 2.1. Pcv could be easily measured several times in the same preparation, either by total venous occlusion or regional venous occlusion using a Swan-Ganz balloon catheter. In addition, Pcv did not require an isogravimetric state for its determination. These data suggest that the major sites of filtration and vascular capacitance in the pulmonary circulation reside in the microvessels and that the more easily determined Pcv is an adequate measure of the average capillary filtration pressure in the lungs.     

Effects of pulmonary congestion on airway reactivity to histamine aerosol in dogs

We examined the effect of acute pulmonary vascular congestion on bronchial reactivity in dogs in a standard challenge protocol. Airway responsiveness to histamine whose concentration was varied in a stepwise incremental fashion was assessed from changes in pulmonary resistance (RL) and dynamic compliance (Cdyn) in 10 anesthetized dogs. Brief acute pulmonary congestion was created by inflating a balloon placed in the left atrium to raise left atrial pressure to 20-30 cmH2O for 1 min. Pulmonary congestion did not change RL in the control condition. However, after histamine inhalation, RL was further increased by pulmonary congestion, making the two effects synergistic. This phenomenon could not be observed with vagi cut. Pulmonary congestion decreased Cdyn in all dogs regardless of histamine concentration, with or without vagotomy. We conclude that pulmonary vascular congestion makes the bronchi hyperreactive through vagal reflexes. The reduction in Cdyn caused by pulmonary congestion appears to stem mainly from the narrowing of peripheral airways by adjacent vascular engorgement.     

Influence of alpha-chloralose on reflex control of the cardiovascular system in lambs

Alpha-chloralose is an anesthetic agent sometimes used for experiments in fetal and neonatal cardiovascular physiology. However, its effect on baseline cardiovascular variables and reflex control of the circulatory system has not been determined in young animals. We, therefore, investigated the effect of chloralose on blood pressure, heart rate and baroreflex activity in 12 lambs. Each lamb was anesthetized and a single-lumen catheter was placed in the inferior vena cava and a double-lumen balloon-tipped catheter was placed in the descending aorta. Following recovery from surgery for at least 48 h, blood pressure and heart rate were measured during quiet wakefulness and 30 min following the administration of polyethylene glycol-400 or alpha-chloralose (30, 60 or 90 mg/kg of body weight). Baroreflex activity was assessed by reflex slowing of the heart during an acute increase in blood pressure, produced by inflating the balloon in the descending aorta. Administration of polyethylene glycol-400 alone did not significantly affect blood pressure, heart rate or baroreflex activity. However, alpha-chloralose significantly decreased baroreflex activity in all the doses tested, compared to control responses obtained following the administration of polyethylene glycol-400 alone. Baseline blood pressure and heart rate were increased by 30 and 60 mg/kg of alpha-chloralose, whereas, 90 mg/kg decreased the blood pressure and did not change heart rate. We conclude that alpha-chloralose significantly alters baseline cardiovascular variables as well as reflex circulatory control in lambs. These effects should be taken into consideration when evaluating studies done during alpha-chloralose anesthesia.     

Furosemide reduces lung fluid filtration in lambs with lung microvascular injury from air emboli

To study the effects of furosemide on the neonatal pulmonary circulation in the presence of lung injury, we measured pulmonary arterial and left atrial pressures, cardiac output, lung lymph flow, and concentrations of protein in lymph and plasma of nine lambs that received furosemide, 2 mg/kg iv, during a continuous 8-h intravenous infusion of air. Air embolism increased pulmonary vascular resistance by 71% and nearly tripled steady-state lung lymph flow, with no change in lymph-to-plasma protein ratio. These findings reflect an increase in lung vascular protein permeability. During sustained lung endothelial injury, diuresis from furosemide led to a rapid reduction in cardiac output (average 29%) and a 2-Torr decrease in left atrial pressure. Diuresis also led to hemoconcentration, with a 15% increase in both plasma and lymph protein concentrations. These changes were associated with a 27% reduction in lung lymph flow. In a second set of studies, we prevented the reduction in left atrial pressure after furosemide by inflating a balloon catheter in the left atrium. Nevertheless, lymph flow decreased by 25%, commensurate with the reduction in cardiac output that occurred after furosemide. In a third series of experiments, we minimized the furosemide-related decrease in cardiac output by opening an external fistula between the carotid artery and jugular vein immediately after injection of furosemide. In these studies, the reduction in lung lymph flow (average 17%) paralleled the smaller (17%) decrease in cardiac output. These results suggest that changes in lung vascular filtration pressure probably do not account for the reduction in lung lymph flow after furosemide in the presence of lung vascular injury.(ABSTRACT TRUNCATED AT 250 WORDS)     

An update on cardiovascular malformations in congenital rubella syndrome

BACKGROUND : Congenital rubella syndrome (CRS) has long been characterized by the triad of deafness, cataract, and cardiovascular malformations (CVMs). While initial reports identified patent ductus arteriosus (PDA) as the primary CVM in CRS, the exact nature of the CVMs found in CRS has not been well established. METHODS : We searched the English literature from 1941 through 2008 to identify studies that used cardiac catheterization or echocardiography to evaluate the CVMs in CRS. RESULTS : Of the 121 patients in the 10 studies with catheterization data, 78% had branch pulmonary artery stenosis, and 62% had a PDA. In 49% of cases, both branch pulmonary artery stenosis and PDA were present, whereas isolated branch pulmonary artery stenosis and isolated PDA were found in 29 and 13% of cases, respectively. Of the 12 patients in the 10 studies with echocardiographic data, PDA was more common than branch pulmonary artery stenosis, but this finding is greatly limited by the small numbers of patients and limitations of echocardiography. Although published studies of CVMs in CRS have in general reported PDA as the CVM phenotype most commonly associated with CRS, among CRS cases evaluated by catheterization, branch pulmonary artery stenosis was actually more common than PDA. Moreover, although the combination of branch pulmonary artery stenosis and PDA was more common than either branch pulmonary artery stenosis or PDA alone, isolated branch pulmonary artery stenosis was twice as common as isolated PDA. CONCLUSION : Among children with suspected CRS, clinical evaluations for the presence of CVMs should include examinations for both branch pulmonary artery stenosis and PDA. Birth Defects Research (Part A), 2010. © 2009 Wiley‐Liss, Inc.