Minimally Invasive Repair of Pectus Carinatum in Patients Unsuited to Bracing Therapy

Background

We used an Abramson technique for minimally invasive repair of pectus carinatum in patients who preferred surgery to brace therapy, had been unsuccessfully treated via brace therapy, or were unsuitable for brace therapy because of a rigid chest wall.

Methods

Between July 2011 and May 2015, 16 patients with pectus carinatum underwent minimally invasive surgery.

Results

The mean age of the patients was 24.35±13.20 years (range, 14–57 years), and all patients were male. The percentage of excellent aesthetic results, as rated by the patients, was 37.5%, and the percentage of good results was 56.25%. The preoperative and postoperative Haller Index values were 2.01±0.19 (range, 1.60–2.31), and 2.22±0.19 (range, 1.87–2.50), respectively (p-value=0.01), and the median hospital stay was 7.09±2.91 days (range, 5–15 days). Only one patient experienced postoperative complications.

Conclusion

Minimally invasive repair is effective for the treatment of pectus carinatum, even in adult patients.

Prosthetic graft interposition of the brachiocephalic veins or superior vena cava combined with resection of malignant tumours: graft patency and risk factors for graft occlusion

BACKGROUND

We aimed to assess graft patency in patients undergoing prosthetic graft interposition of the brachiocephalic veins (BCVs) or the superior vena cava (SVC) combined with resection of malignant tumours.

METHODS

A retrospective analysis was conducted on 16 patients who underwent prosthetic graft interposition of the BCVs or the SVC between 1998 and 2012.

RESULTS

Among a total of 20 grafts in 16 patients (unilateral graft interposition in 12, bilateral graft interposition in 4), 8 grafts were occluded in 8 patients. Overall graft patency rate was 64.6%, 42.4% at the 2- and 5-year follow-up. Graft patency rate of the left BCV was significantly lower than that of the right BCV or the SVC (2-year patency, 38.1% vs. 81.8%, P=0.024). In univariate analysis, the superior anastomosis site [left BCV vs. right BCV; hazard ratio (HR) =2.312; 95% confidence interval (CI), 1.015-5.265; P=0.046], the inferior anastomosis site (right atrial appendage vs. SVC; HR =2.409; 95% CI, 1.124-5.161; P=0.024), and interruption of warfarin (HR =5.015; 95% CI, 1.106-22.734; P=0.037) were significant risk factors for graft occlusion. Graft occlusive symptoms were identified in 4 patients who underwent unilateral graft interposition.

CONCLUSIONS

Prosthetic graft interposition between the left BCV and the right atrial appendage resulted in a significant rate of graft occlusion. Prosthetic graft interposition of the bilateral BCVs and long-term warfarin therapy may be necessary to prevent graft occlusive symptoms.

Significance of KIT exon 17 mutation depends on mutant level rather than positivity in core-binding factor acute myeloid leukemia

KIT exon 17 mutation is a poor prognostic factor in core-binding factor acute myeloid leukemia. However, the mutation detection method used for risk assessment is not assigned. It is necessary to verify the analytical and clinical performance before applying new methods. Herein, we firstly applied a highly sensitive allele-specific, real-time quantitative PCR (AS-qPCR) assay to analyze KIT mutations, which demonstrated excellent sensitivity and specificity. Much higher incidence of KIT mutations (62.2%, 69/111) and prevalence of multiple mutations (43.5%, 30/69) were observed using AS-qPCR, which meant the existence of multiple KIT mutant subclones. The relative KIT mutant level was variable (median, 0.3 per control allele 100 copies, 0.002–532.7) and was divided into two groups: high (⩾10, n=26) and low (<10) mutant level. Interestingly, rather than mutation positivity, mutant level was found to be associated with clinical outcome. High mutant level showed significantly inferior overall survival (P=0.005) and event-free survival (P=0.03), whereas low level did not influence the prognosis. The follow-up data showed that the mutant level were along with fusion transcripts in the majority (n=29), but moved separately in some cases, including the loss of mutations (n=5) and selective proliferation of minor clones (n=2) at relapse. This study highlighted that the KIT mutation should be analyzed using sensitive and quantitative techniques and set a cutoff level for identifying the risk group.

Quantitative fragment analysis of FLT3-ITD efficiently identifying poor prognostic group with high mutant allele burden or long ITD length

Mutation of the fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), which is one of the most frequent genetic alterations, strongly contributes to an increased risk of treatment failure and to poor prognosis. In this study, we established quantitative fragment analysis of FLT3-ITD simultaneously measuring mutant allele burden and length, verified the analytical performance and evaluated the clinical significance in adult acute myeloid leukemia (AML) patients. FLT3-ITD was detected in 73 of 363 adult AML patients (20.1%) and high mutant allelic burden (⩾50%, n=13) and long ITD length (⩾70 base pairs, n=15) were significantly associated with inferior overall survival (OS; P=0.002 and 0.005, respectively) and event-free survival (EFS; P=0.004 and 0.007, respectively). FLT3-ITD poor prognostic group was identified as patients with high allele burden or long ITD length (n=24), which revealed significant adverse clinical outcome for both OS (P<0.001) and EFS (P<0.001). In cytogenetically normal AML, even FLT3-ITD low allele burden and short length was associated with poorer OS (P=0.037) and EFS (P=0.044) than wild type, whose influence was overcome when hematopoietic stem cell transplantation was performed. In minimal residual disease monitoring, FLT3-ITD negativity after consolidation therapy was a valuable predictor of better OS (P<0.001) and EFS (P<0.001). FLT3-ITD poor prognostic group with high mutant allele burden or long ITD length is efficiently identified by quantitative fragment analysis.

A comparison of the proposed classifications for the revision of N descriptors for non-small-cell lung cancer

OBJECTIVES

Several new classifications have been proposed for revision of the N descriptors for non-small-cell lung cancer (NSCLC), but external validation is required. The aim of this study was to validate various newly proposed nodal classifications and to compare the discrimination abilities of these classifications.

METHODS

A retrospective analysis was conducted of 1487 patients who underwent complete resection with systematic lymph node dissection for NSCLC between 2000 and 2008. Four nodal classifications based on the following categories were analysed: zone-based classification (single-zone N1, multiple-zone N1, single-zone N2 and multiple-zone N2), number-based classification (the number of metastatic lymph nodes; 1-2, 3-6 and ≥7), rate-based classification (ratio of the number of metastatic lymph nodes to the total number of resected lymph nodes; ≤15, 15-40 and >40%) and the combination of location- and number-based classification (N1: 1-3, N1: ≥4, N2: 1-3 and N2: ≥4). Concordance (C)-index and net reclassification improvement (NRI) index were used to assess the discrimination abilities of the models.

RESULTS

In multivariate analysis, all of the newly proposed classifications were independent predictors (P < 0.001) of overall survival (OS) after adjustment for significant variables (age, tumour histology and pathological T status). The C-indices of the classifications based on the nodal zone, nodal number, rate and location alongside the number of metastatic lymph nodes were 0.6179, 0.6280, 0.6203 and 0.6221, respectively; however, the differences in the C-indices were statistically insignificant. Compared with the zone-based classification, the NRI for OS of classifications based on the nodal number, rate and location with number were 0.1101, 0.0972 and 0.0416, respectively.

CONCLUSIONS

All four proposed classifications based on the nodal zone, nodal number, rate and the combination of location and number are prognostically valid and could serve as future N descriptors after complete resection of NSCLC. The discrimination ability was not significantly different among the four proposed classifications, although the number-based classification tended to have a higher predictive ability compared with the zone-based classification. Future studies with an in-depth discussion are needed to clarify optimal future N descriptors for NSCLC.

Video-assisted thoracic surgery for bronchogenic cysts: is this the surgical approach of choice?

OBJECTIVES

Although there is no consensus on the management of bronchogenic cyst, most surgeons advocate early removal, even in asymptomatic patients. To evaluate the feasibility and safety of video-assisted thoracic surgery (VATS) in the management of bronchogenic cysts and long-term follow-up, a retrospective analysis was performed.

METHODS

From January 1995 to April 2013, we retrospectively reviewed the charts of 113 patients who underwent VATS resection of bronchogenic cysts in our institution. Resection of the bronchogenic cysts by VATS was initially performed in patients who had a cyst in the thoracic cavity and no evidence of severely dense adhesion to other organs or tissues on a CT scan. Also, patients with a history of previous thoracic surgeries, in addition to those with concomitant diseases requiring surgical treatment, were enrolled in our series. Operations were carried out using the conventional three-port technique and histological examinations confirmed the diagnosis of benign bronchogenic cyst containing a ciliated columnar epithelial lining.

RESULTS

The median size of the cysts was 3.7 cm in their greatest diameter (range, 1-10 cm). One hundred and nine patients with bronchogenic cyst were resected completely by VATS. In 4 cases, VATS was converted to open thoracotomy or median sternotomy: major adhesion to the bronchus in 2, left innominate venous injury in 1 and repair of bronchial tear by surgery in 1. We identified 5 intraoperative complications of tracheobronchial tear, vascular injury and oesophageal laceration. The median operation time was 96.8 min (range, 15-320 min). There were no operative mortalities or major postoperative complications. Patients with VATS excision were discharged after a median of 3.7 days postoperatively. The long-term follow-up ranged from 1 to 11 years, with a median follow-up of 4.2 years. There were no late complications or recurrences.

CONCLUSIONS

Considering the low conversion and complication rate, VATS was safe and effective in the resection of the bronchogenic cysts. The size and the location of cysts were not important considerations in selecting the surgical method. VATS excision should be considered the primary therapeutic option in the management of patients with bronchogenic cysts.

Chylothorax complicating pulmonary resection for lung cancer: effective management and pleurodesis

BACKGROUND

Chylothorax associated with pulmonary resection for lung cancer, although rare, must be considered as a potential complication during thoracic surgery. In the present study, we investigated the effectiveness of a conservative approach (diet or pleurodesis) to the management of chylothorax.

METHODS

Between January 2000 and December 2010, 3,120 consecutive patients underwent pulmonary resection and mediastinal lymph node dissection at our institution. Among them, 67 patients with confirmed chylothorax were retrospectively reviewed.

RESULTS

Right-sided chylothorax was more common than left-sided chylothorax (p=0.033). All patients were initially treated with nil per os (NPO; n=46) or a low long-chain triglyceride (LCT) diet (n=21). In the NPO group, 24 patients were successfully treated with diet alone and 20 underwent pleurodesis. In the LCT group, 10 patients were successfully treated with diet alone; of the 11 remaining patients, 4 patients improved after NPO. The 7 patients who did not improve with NPO underwent pleurodesis. No significant differences in chest tube output before and after initial treatment, length of stay, or success rate were observed between patients initially treated with NPO and those receiving low LCT. All 32 pleurodeses performed in 27 patients were successful. Two patients underwent surgery without pleurodesis after dietary treatment failure. Postoperative air leakage or drainage for 5 days greater than 21.6 mL/kg were independent risk factors for dietary treatment failure.

CONCLUSIONS

Conservative treatment, including pleurodesis, should be the first choice of treatment for chylothorax complicating pulmonary resection.

Gastric conduit cancer after oesophagectomy for oesophageal cancer: incidence and clinical implications

OBJECTIVES

Gastric conduit cancer (GCC), which is a carcinoma that arises in the gastric conduit after oesophagectomy, often negatively affects long-term survivors of oesophageal cancer. The aim of this study was to evaluate the incidence and clinical implications of GCC.

METHODS

We reviewed data for 863 patients who underwent an oesophagectomy and a reconstruction of the gastric conduit from 1993 to 2011 for oesophageal cancer.

RESULTS

A total of 18 cases of GCC in 18 patients were identified. Cumulative incidence rates of GCC were 2.4% at 5 years and 5.7% at 10 years. The median interval between oesophagectomy and detection of gastric tube cancer was 5.0 years (range, 1-16 years). Ten patients were incidentally diagnosed with GCC under periodic endoscopy. All cases of gastric tube cancer were adenocarcinoma and 12 cases were located at the antrum of the gastric conduit. For GCC treatment, endoscopic submucosal dissection was performed in 6 patients, total gastric conduit gastrectomy with colon interposition in 3 patients and chemotherapy in 6 patients. Five patients received conservative treatment alone. The 5-year survival rate of all patients was 22.2%. The 3-year survival rates of the patients who underwent endoscopic resection, total gastrectomy with colon interposition or chemotherapy or conservative treatment were 100, 50, and 9.1%, respectively (P = 0.003).

CONCLUSIONS

Patients had a constant risk of GCC occurrence after oesophagectomy for oesophageal cancer. Endoscopic or surgical resection for early GCC showed favourable outcomes compared with chemotherapy or conservative treatment for advanced GCC. A regular and long-term follow-up, including detailed endoscopy, is essential for the early detection of GCC in patients who underwent oesophagectomy for oesophageal cancer.

Esophageal Cancer Associated with Multiple Primary Cancers: Surgical Approaches and Long-term Survival

BACKGROUND

The presence of multiple primary cancers (MPCs) in patients with esophageal cancer often presents physicians with a difficult therapeutic decision, because little is known about the appropriate treatment and long-term survival. The purpose of this study was to evaluate appropriate surgical approaches and long-term survival after surgery for esophageal cancer associated with MPCs.

METHODS

Data from 622 patients who underwent surgery for primary esophageal cancer between 1989 and 2008 were reviewed retrospectively to identify the presence of MPCs.

RESULTS

A total of 96 MPCs were identified in 90 (14.5 %) patients. The three leading MPCs were stomach cancer (n = 36, 37.5 %), head and neck cancer (n = 18, 18.8 %), and lung cancer (n = 18, 18.8 %). The rate of curative resections for both esophageal cancer and MPCs was 87.5 % (28/32) in patients with stomach cancer, 47.1 % (8/17) in head and neck cancer, and 52.9 % (9/17) in lung cancer (P = 0.006). The 5-year survival rates after surgery for esophageal cancer in patients associated with stomach, lung, and head and neck cancer were 52.7, 27.0, and 9.2 %, respectively (P = 0.011).

CONCLUSIONS

A range of surgical approaches for esophageal cancer is available in patients associated with MPCs. However, curative resections for primary esophageal cancer associated with MPCs are feasible in highly selected patients. Therefore, a multidisciplinary team management approach is essential for customized treatment strategies in patients with esophageal cancer associated with MPCs.

Surgical outcomes of pulmonary mucoepidermoid carcinoma: a review of 23 cases

BACKGROUND

The aim of the present study was to evaluate the oncologic characteristics of pulmonary mucoepidermoid carcinoma (PMEC) and the efficacy of surgical resections.

MATERIALS AND METHODS

The surgery for PMEC was performed in 23 patients at Asan Medical Center from January 2000 to December 2010. They accounted for 0.8% of all surgically resected pulmonary neoplasm in the center. The medical records of these patients were reviewed retrospectively.

RESULTS

This study group was composed of 13 males (56.5%) and 10 females (43.5%). Median age was 41 years (range, 10 to 75 years). Complete resection with systematic mediastinal lymph node dissection was performed in all patients. There were three postoperative complications: atelectasis in one patient and chylothorax in two patients. There was no postoperative mortality. The median follow-up duration was 68 months (range, 13 to 115 months). In one patient, recurrent disease was found 73 months after surgery. All patients were followed without mortality until the end of this study. The 5- and 8-year disease-free survival rates were 100 and 90.9%, respectively.

CONCLUSION

Complete surgical resection with systematic lymph node dissection is an effective treatment for patients with PMEC and provides favorable prognosis.

Gastric tube cancer after esophagectomy for esophageal cancer: A single-center experience with meta-analysis of 145 cases

e14573

Background: Gastric tube cancer (GTC) defined as carcinoma arising in the gastric conduit after esophagectomy, is often crucial in long-term survivors of esophageal cancer. The aim of this study was to determine the optimal approach to manage GTC. Methods: We reviewed data of 863 patients who underwent esophagectomy and reconstruction with the gastric conduit for esophageal cancer at Asan Medical Center from 1993 to 2011 and identified 28 cases of GTC. We also searched through the PubMed database and included additional 117 cases of GTC from 13 studies to conduct meta-analysis. Results: In our cases, the incidence rate of GTC was 3.2%. The median interval between esophagectomy and GTC detection was 3.1 (0.6-15.2) years. Twelve (42.9%) patients were asymptomatic and diagnosed by periodic endoscopy. The Most common histologic type of GTC was adenocarcinoma (57.1%) and fifteen (53.6%) were located on the lower third of gastric tube. Chemotherapy, total gastrectomy or palliative treatment was performed in 10, 5, 2 patients, respectively. Eleven (39.3%) patients refused the further treatment for GTC. Mean survival duration of 28 patients after the diagnosis of GTC was 29.1 months. In meta-analysis, The cumulative occurrence of 5, 8 years was 59.5%, 87.8%, respectively. Two-year survival rate of the patients who underwent endoscopic resection, surgical resection or palliative treatment was 100%, 61.6%, 5.2%, respectively. The patients who underwent endoscopic resection had a better prognosis than those who underwent surgical resection or those who received palliative treatment (p=0.047, p=0.000, respectively). Conclusions: After esophagectomy for esophageal cancer, patients had a constant risk of GTC occurrence up to 8 years approximately. The patients who diagnosed as advanced-state GTC had a poor prognosis. However, endoscopic resection as a minimally invasive treatment for early-GTC represented a feasible prognosis compared with those of operative resection or palliative treatment. Therefore, a long-term follow-up including detailed endoscopy is essential for the better outcomes in patients who underwent esophagectomy for esophageal cancer.

Errors in ABO labeling of deceased donor kidneys: case reports and approach to ensuring patient safety

Patient safety in transplantation depends on accurate testing, transcription and transmission of the ABO types of the donor and recipient. Similar to 'near-miss' transfusion labeling errors, three cases of mislabeled ABO types on deceased donor kidney containers were recognized through a pretransplant verification process. Six steps to confirming the organ and ABO identification were developed to ensure safety of the patient and prevent liability for the transplant team and facility. In each case, rapid recognition and documentation of the error source, on site confirmation of the ABO type of the accompanying blood specimen, and full disclosure to the patient and family permitted safe transplantation and avoided the need to pursue a more conservative course that would have required discarding the organs. We advocate following these measures in determining whether to persevere with transplantation of a mislabeled organ.

Identification of two new alleles in a single Korean individual, HLA-B*1568 and HLA-DRB1*1208

We have identified a new HLA-B*15 allele and a new HLA-DRB1*12 allele, named B*1568 and DRB1*1208, respectively. The alleles were identified using a combination of sequence specific primers, reverse line sequence specific oligonucleotide probing and sequence-based typing. Both alleles were identified in a single individual of Korean origin. HLA-B*1568 appears to be an HLA-B*4801/B*1507 hybrid combining the exon 2 sequence of B*4801 and the exon 3 and 4 sequences of B*1507. Exon 2 of DRB1*1208 was most similar to DRB1*1201 or 1206, with a single mismatch at nucleotide position 165 (A to C). At the protein level, this substitution results in a phenylalanine substitution at position 26 that creates an identical amino acid sequence to DRB3*0202 between amino acid positions 17 and 36.

Photocatalytic oxidation and decomposition of acetic acid on titanium silicalite

Transient reaction of adsorbed monolayers of acetic acid was used to characterize the photocatalytic properties of titanium silicalite zeolites (TS-1). The TS-1 zeolites having Si/Ti ratios of 5, 12.5, and 50 are effective catalysts at room temperature for both photocatalytic oxidation (PCO) and decomposition (PCD) of acetic acid. The rates of PCO are higher than the rates of PCD for each catalyst. Acetic acid oxidized photocatalytically in 0.2% O2 to form gas-phase CO2 and CH4 and adsorbed H2O on the TS-1 catalysts, whereas no CH4 formed on Degussa P25 TiO2. Isotope labeling showed that, on both TiO2 and TS-1 catalysts, the alpha-carbon formed CO2 whereas the beta-carbon formed CH4 and CO2. The rates of oxidation of the two carbons have different dependencies on UV intensity. The catalysts with higher Si/Ti ratios adsorbed significantly more acetic acid, and the PCO rates per gram of titanium are highest on the TS-1 catalyst with the lowest Ti content, apparently because a larger fraction of the Ti atoms are surface atoms on this catalyst. During PCD in an inert atmosphere, CO2, CH4, and C2H6 formed on TiO2 and on the catalyst with a Si/Ti ratio of 5, but C2H6 was not detected on the other catalysts. The CO2/CH4 selectivity during PCD increased with increasing Si/Ti ratio. The first step in PCO and PCD on TS-1 catalysts appears to be similar and involves formation of a CH3 radical.

Left atrial myxosarcoma with systemic metastasis: a case report

The term myxosarcoma is currently not used in standard classification for soft tissue tumors, but restricted to cardiac tumors. Primary cardiac myxosarcoma is a very rare disease and is difficult to differentiate from myxoma clinically and pathologically. We report a case of left atrial myxosarcoma with widespread systemic metastasis in a 21-yr-old male. The patient presented with sudden onset of intermittent dyspnea and orthopnea. Echocardiography showed a mobile, pedunculated tumor, 7.5x5x2 cm in size, at left atrium. Histologically, the excised tumor showed an amorphous finely fibrillar and mucinous stroma, in which irregular cords and clusters of lepidic cells and large stellate cells with plump vesicular nuclei resembled the usual type of cardiac myxoma were noted. And it showed focally cellular area with great nuclear pleomorphism and frequent mitoses. The patient received combination chemotherapy, peripheral blood stem cell collection transplantation and operations for systemic metastases in the brain, skeletal muscle and lung. He is alive at present 37 months after initial diagnosis and has no more new metastatic lesion.

Nontwist quarter-wave liquid-crystal cell for a high-contrast reflective display

We propose an optical configuration of a nontwist quarter-wave liquid-crystal cell for a high-contrast reflective display that can be applied to most nontwist display modes. By fabricating a homogeneous cell with the proposed configuration, we have demonstrated a high contrast ratio of 50:1 without using a wideband retardation film.

Natural cytotoxicity of murine cytomegalovirus-infected cells mediated by mouse lymphoid cells: role of interferon in the endogenous natural cytotoxicity reaction

Lymphoid cells from unstimulated normal C57BL/6J mice were shown to lyse murine cytomegalovirus (MCMV)-infected syngeneic mouse embryo fibroblasts but not uninfected mouse embryo fibroblasts. This cytotoxicity by mouse effector cells was not restricted to MCMV-infected syngeneic cells since MCMV-infected xenogeneic rat heart fibroblasts were also lysed. Characterization of the effector cells mediating this cytotoxicity against MCMV-infected cells indicated that the effector cells are similar to described natural killer (NK) cells mediating lysis of tumor cells and virus-infected cells. Because of the described augmentation of NK activity by interferon, we examined the role of interferon in the NK reaction. Although low levels of virus-induced interferon were detectable in supernatants of MCMV-infected mouse embryo fibroblasts, no interferon was detectable in supernatants of MCMV-infected rat heart fibroblasts, a target significantly more sensitive to NK cytolysis than infected mouse embryo fibroblasts. We were able to augment the NK reaction against MCMV-infected cells by in vitro treatments with interferon. However, the amounts of interferon required for augmentation were significantly greater than the amounts generated by infected target cells. In vitro interferon-stimulated NK cells retained selective cytotoxic activity since they continued to remain incapable of lysing uninfected target cells. MCMV-infected rat heart fibroblasts induced more interferon and were also more susceptible to NK activity than MCMV-infected mouse embryo fibroblasts. In spite of this difference in interferon-inducing capacity, there was no augmentation of cytotoxicity of MCMV-infected mouse embryo fibroblasts when mouse splenocytes were cocultivated with both target cells. Finally, when production of interferon in the NK reaction was inhibited by the addition of actinomycin D, no reduction of NK activity was seen. Our findings suggest that native mouse NK cells can discriminate between MCMV-infected cells and uninfected cells, this ability leading to the selective lysis of the virus-infected cells. Furthermore, although we could demonstrate augmentation of NK activity by interferon, interferon activation of NK cells may not be a necessary precondition for the development of endogenous NK activity.

Blood flow in pulmonary veins: I. Studies in dog and man

The pattern of blood flow in the large extra parenchymal pulmonary veins is pulsatile in both dog and man. This pulsatility is dominated by the changes in left atrial pressure taking place throughout the cardiac cycle. No pulsatile component of low in the large pulmonary veins could be attributed to forward transmission of a flow pulse conducted from the lung capillaries. The findings suggest that there must be a region of considerable compliance in the pulmonary venous system which can absorb pulsations from the lung capillaries and eliminate their transmission to the left atrium.

Blood flow in pulmonary veins: III. Simultaneous measurements of their dimensions, intravascular pressure and flow

Vein flow in the large extraparenchymal pulmonary veins is pulsatile and its wave form has an inverse relationship to left atrial pressure. Extraparenchymal pulmonary veins are thin walled and collapsible. This enables them to behave as highly compliant structures. Dimensional measurements of their cross sectional area in living open chested dogs showed them to be non circular at low left atrial pressures. They rapidly assumed a circular cross section as left atrial pressure rose. Only at pressures above 1.5 kPa (11 mmHg) were the pulmonary veins circular in cross section. The aggregate volume of the large extraparenchymal pulmonary veins, when fully distended, was found to be equal to or greater than one stroke volume of the heart. The extraparenchymal pulmonary veins act as a reservoir to the left atrium so that left ventricular stroke volume can be maintained relatively unaffected by beat by beat changes in right ventricular stroke output. Their behaviour at normal mean left atrial pressures also enables them to isolate the lung capillaries from retrograde transmission of positive pressure transients from the left atrium, which could otherwise impede venous outflow of blood from the lung capillary bed.

Blood flow in pulmonary veins: II. The influence of events transmitted from the right and left sides of the heart

The wave form of blood flow in the large extra parenchymal pulmonary veins has an inverse relationship to the pressure wave form in the left atrium during each cardiac cycle. However, when vein flow from the lungs is separated from the left atrium by diverting it into a constant pressure reservoir, its wave form then resembles a lung capillary flow pulse, though delayed from it in time and reduced in ampliture. The pulsatility of flow in pulmonary veins separated from the left atrium is further reduced when transcapillary pressure is elevated by lung inflation. However, in the intact state, the relation between the pattern of pulmonary vein flow and left atrial pressure remains unaffected by lung inflation. It is postulated that the thin walled extraperenchymal pulmonary veins together behave as a collapsible reservoir which enables outflow from them to be determined by changes in left atrial pressure, in spite of variations of pulsatile flow into them from the lungs.

The physcial properties of human pulmonary arteries and veins

1. We have studied the extensibility of circumferential strips of main pulmonary artery and large pulmonary veins obtained at post mortem from patients of all ages, dying from conditions other than heart and lung disease. 2. The vessel strips were submitted to increasing loads in a tension balance. The pulmonary arteries were found to be readily extensible. This extensibility became less with increasing age. The pulmonary veins were virtually inextensible at all ages. 3. It is postulated that the large extraparenchymal pulmonary veins have a capacitative role in supplying blood from the lungs to the left atrium. This may be accomplished by their collapsible nature, as they have little capability of distension.