Transcatheter occlusion of a post-Fontan residual hepatic vein to pulmonary venous atrium communication using the Amplatzer septal occluder.
A residual hepatic vein to left atrial communication may result in progressive cyanosis after the Fontan procedure. This problem has usually been treated surgically by ligation or re-inclusion of the residual hepatic vein in the Fontan circulation. Previous attempts at transcatheter closure of such veins have been unsuccessful. An Amplatzer septal occluder was successfully used for transcatheter closure of a post-Fontan hepatic vein to pulmonary venous atrium fistula in an 8 year old boy. (+info
Effects of respiratory cycle on pulmonary venous flow and cardiac cycle on pulmonary venous diameter of dogs: a transesophageal echocardiography study.
We investigated 12 anesthetized normal dogs using transesophageal echocardiography to understand the effects of respiration on the pulmonary venous flow. Additionally, we observed whether the diameter of the pulmonary vein changes with the heart beat. The pulsed Doppler wave form of pulmonary venous flow predominantly demonstrated two backward flows, with one peak occurring during ventricular systole and another during ventricular diastole. Sometimes a small forward flow occurred during left atrial contraction. In comparison with expiration, the peak velocity and velocity-time integral of the flow wave under inspiration occurred during both systole and diastole were significantly smaller. The diameter of the pulmonary vein decreased during left atrial contraction and increased during left ventricular systole and diastole. (+info
Site of functional bronchopulmonary anastomoses in sheep.
The location of bronchopulmonary anastomoses has long been a topic of discussion, and pre-, post-, and capillary sites have all been demonstrated in postmortem examinations. However, there have been few studies that have provided insight into the patency and function of these anastomoses in the intact lung. To identify these functional sites where the bronchial circulation anastomoses with the pulmonary circulation, we studied sheep lungs in situ serial sectioned with high-resolution computed tomography (CT). Differences in radiodensities of blood, air, and nonionic contrast medium were used to differentiate and localize airways and vessels and to identify the effluent from the bronchial circulation. After an initial series of scans to identify the pulmonary arteries and veins adjacent to airways 2-12 mm in diameter, contrast material was infused into the bronchial artery. In three sheep, the major accumulation of contrast medium was found in pulmonary veins. In one of the sheep, a comparable number of pulmonary arteries and veins contained contrast medium. Serial histologic sections were able to identify small bronchial venules lying within subepithelial bronchial folds that drain directly into pulmonary veins. These results using serial CT and histologic images suggest that drainage from the intraparenchymal bronchial vasculature is predominantly into postcapillary pulmonary vessels. (+info
Pulmonary venous flow in hypertrophic cardiomyopathy as assessed by the transoesophageal approach. The additive value of pulmonary venous flow and left atrial size variables in estimating the mitral inflow pattern in hypertrophic cardiomyopathy.
AIMS: This study was conducted to assess the characteristics of the pattern of pulmonary venous flow and to document the interaction of this flow and left atrial function with the pattern of mitral inflow in hypertrophic cardiomyopathy. METHODS AND RESULTS: Pulmonary venous and mitral flows were evaluated by the transoesophageal approach in 80 patients with hypertrophic cardiomyopathy. Left atrial size and function were measured by the transthoracic approach. Their values were compared with those obtained from 35 normal controls. Twelve patients showed significant (> 2+) mitral regurgitation. As a group, hypertrophic cardiomyopathy patients showed increased atrial reversal flow and longer deceleration time of the diastolic wave, but a wide variability of pulmonary venous flow patterns were observed. Thirty patients (37.5%) had pseudonormal mitral flow patterns. Stepwise multilinear regression analysis identified the ratio of systolic to diastolic pulmonary venous flow velocity, the ratio of velocity-time integrals of both flow waves at atrial contraction, the left atrial minimal volume and the systolic fraction as independent predictive variables of the mitral E/A wave velocity ratio (r = 0.82). By logistic regression, the former three variables were selected as independent predictive covariates of a pseudonormal mitral flow pattern (sensitivity: 83%, specificity: 90%). The ratio of velocity-time integrals of both atrial waves was the most important predictive variable in both analyses. CONCLUSIONS: The observed variability in the configuration of pulmonary venous flow velocity waveform is related to what occurs in transmitral flow in patients with hypertrophic cardiomyopathy. Significant mitral regurgitation is not an independent correlate of pseudonormal mitral inflow patterns in these patients. Our results further emphasize the complementary, additive value of the pulmonary venous flow velocity pattern and left atrial size in the interpretation of the mitral flow velocity pattern, and indirectly suggest the underlying increased left ventricular filling pressures of patients with hypertrophic cardiomyopathy and pseudonormal mitral flow patterns. (+info
The functional anatomy of the bronchial circulation of the domestic fowl.
The bronchial circulation was studied in 25 adult domestic fowls. The right and left bronchial arteries originated caudal to the syrinx from a bronchoesophageal artery which is a branch of the right common carotid artery. Each bronchial artery ramified on the wall of the extrapulmonary part of the corresponding primary bronchus and finally anastomosed directly with a branch of the pulmonary artery at the hilus of the lung. Thr bronchial artery did not accompany the intrapulmonary part of the primary bronchus. The branches of each bronchial artery formed an anastomosing network on the wall of the extrapulmonary part of the primary bronchus. The calibre of the bronchial artery at its anastomosis with the branch of the pulmonary artery was greater than at its origin from the bronchoesophageal artery. Intravenous injections of Lycopodium spores indicated that the blood flows from the pulmonary artery into the bronchial artery. Small bronchial veins drained the extrapulmonary part of the primary bronchus into the pulmonary vein and the oesophageal veins. The intrapulmonary part of the primary bronchus was supplied by branches of the pulmonary artery and drained by tributaries of the pulmonary vein. The blood supply to the primary bronchus could constitute a shunt capable of passing blood from the pulmonary artery into the pulmonary vein without going through the exchange tissue. The parabronchial (atrial) muscles received a blood supply directly from the exchange tissue via septal venules which formed a network underneath the muscle bundles, without actually penetrating between the muscle cells. These venules drained into atrial veins which were tributaries of the pulmonary vein. The atrial muscles probably also received oxygen by direct diffusion from the parabronchial lumen. The pleura was supplied by the oesophageal branches of the bronchoesophageal artery, and by small twigs from the internal thoracic and intercostal arteries. (+info
Defibrillation-guided radiofrequency ablation of atrial fibrillation secondary to an atrial focus.
OBJECTIVES: Our aim was to evaluate a potential focal source of atrial fibrillation (AF) by unmasking spontaneous early reinitiation of AF after transvenous atrial defibrillation (TADF), and to describe a method of using repeated TADF to map and ablate the focus. BACKGROUND: Atrial fibrillation may develop secondary to a rapidly discharging atrial focus that the atria cannot follow synchronously, with suppression of the focus once AF establishes. Focus mapping and radiofrequency (RF) ablation may be curative but is limited if the patient is in AF or if the focus is quiescent. Early reinitiation of AF has been observed following defibrillation, which might have a focal mechanism. METHODS: We performed TADF in patients with drug-refractory lone AF using electrodes in the right atrium (RA) and the coronary sinus. When reproducible early reinitiation of AF within 2 min after TADF was observed that exhibited a potential focal mechanism, both mapping and RF ablation were performed to suppress AF reinitiation. Clinical and ambulatory ECG monitoring was used to assess AF recurrence. RESULTS: A total of 44 lone AF patients (40 men, 4 women; 32 persistent, 12 paroxysmal AF) with a mean age of 58+/-13 years underwent TADF. Sixteen patients had early reinitiation of AF after TADF, nine (20%; 5 paroxysmal) exhibited a pattern of focal reinitiation. Earliest atrial activation was mapped to the right superior (n = 4) and the left superior (n = 3) pulmonary vein, just inside the orifice, in the seven patients who underwent further study. At the onset of AF reinitiation, the site of earliest activation was 86+/-38 ms ahead of the RA reference electrogram. The atrial activities from this site were fragmented and exhibited progressive cycle-length shortening with decremental conduction to the rest of the atrium until AF reinitiated. Radiofrequency ablation at the earliest activation site resulted in suppression of AF reinitiation despite pace-inducibility. Improved clinical outcome was observed over 8+/-4 months' follow-up. CONCLUSIONS: Transvenous atrial defibrillation can help to unmask, map, and ablate a potential atrial focus in patients with paroxysmal and persistent AF. A consistent atrial focus is the cause of early reinitiation of AF in 20% of patients with lone AF, and these patients may benefit from this technique. (+info
Prostanoid receptors involved in the relaxation of human pulmonary vessels.
1. To characterize the prostanoid receptors on human pulmonary smooth muscle involved in vasodilatations, isolated arteries and veins were contracted with norepinephrine (10 microM) and vessels were subsequently challenged with different prostanoid-receptor agonists in the absence or presence of selective antagonists. 2. Prostaglandin D2 (PGD2) and the selective DP-receptor agonist, BW245C, induced relaxations in the contracted human pulmonary venous preparations. The pD2 values were: 6.88+/-0.11 (n=17) and 7.31+/-0.12 (n=5), respectively. The relaxant responses induced by PGD2 were reduced by the selective DP-receptor antagonist, BWA868C, and the estimated pA2 value was 7.84+/-0.16 (n=4). PGD2 and BW245C did not relax contracted human pulmonary arteries. 3. The selective IP-receptor agonists, iloprost and cicaprost, both induced relaxations in the contracted human vascular preparations. The pD2 values for iloprost were: 7.84+/-0.08 (n=6) and 8.25+/-0.06 (n=4) and for cicaprost: 8.06+/-0.12 (n=5) and 8.11+/-0.09 (n=5) in arteries and veins respectively. 4. Prostaglandin E2 (PGE2) and the EP2/EP3-receptor agonist, misoprostol, partially relaxed the contracted venous preparations and the pD2 values were: 8.10+/-0.15 (n=15) and 6.24+/-0.33 (n=3), respectively. These relaxations suggest the presence of an EP receptor in the human pulmonary veins. The contracted human pulmonary arteries did not relax when challenged with PGE2. 5. In human pulmonary venous preparations, the PGE2-induced relaxations were neither modified by treatment with TP/EP4-receptor antagonist, AH23848B (10 and 30 microM, n=6), nor by the DP/EP1/EP2-receptor antagonist, AH6809 (3 microM, n=6). 6. These data suggest that the relaxation induced by prostanoids involved DP-, IP-receptors and to a lesser extent an EP-receptor on human pulmonary venous smooth muscle. In contrast, only the IP-receptor is involved in the prostanoid induced relaxations on human pulmonary arterial smooth muscle. (+info
Fetal pulmonary venous flow into the left atrium relative to diastolic and systolic cardiac time intervals.
OBJECTIVE: To establish the nature and gestational age dependency of the pulmonary venous flow velocity pattern into the left atrium relative to systolic and diastolic phases of the cardiac cycle. DESIGN: This was a cross-sectional study of Doppler measurements of fetal pulmonary venous inflow velocities, which were correlated with simultaneous recordings of transmitral and aortic flow velocity waveforms based on an equal cardiac cycle length (+/- 5%). RESULTS: Successful recordings were obtained in 28 out of 60 (47%) normal singleton pregnancies at 20-36 weeks of gestation. Reproducibility of waveform analysis of the various phases of the cardiac cycle was satisfactory, within-patient variance ranging between 1.7% and 6.5%. A statistically significant increase (p < 0.05) in pulmonary venous time average velocity and velocity integral with advancing gestational age was established. A statistically significant increase (p < 0.05) of the pulmonary flow velocity integral was also found when related to each of the systolic and diastolic segments of the cardiac cycle, with the exception of isovolemic relaxation time. The duration of each of the diastolic and systolic segments of the cardiac cycle, as well as the pulmonary venous velocity integral expressed as a percentage of the cardiac cycle, remained constant with advancing gestational age. CONCLUSIONS: The second half of pregnancy is characterized by pulmonary venous inflow into the left atrium throughout the cardiac cycle. Pulmonary venous inflow into the left atrium occurs predominantly during the filling and ejection phases of the cardiac cycle. Absolute cardiac diastolic and systolic time intervals as well as the percentage distribution of pulmonary venous flow velocity integrals between these cardiac time intervals remain unchanged with advancing gestational age. (+info