Morphologic prognostic factor for thoracoabdominal aortic dilation after acute type A dissection repair

OBJECTIVES

Risk factors for late-term aortic dilation after acute type A aortic dissection repair have not been well examined. The goal of this study was to determine the relationship between the abdominal aortic true lumen location and thoraco-abdominal aortic dilation after surgical repair for acute type A aortic dissection.

METHODS

Patients who were preoperatively diagnosed with acute type A aortic dissection between April 2014 and July 2022 were included in this study. We evaluated the renal artery-level dissected aortic morphology and classified the study population into 2 groups: the ventral (those with the true lumen located on the ventral side) and the dorsal (other patients not assigned to the ventral group) groups, based on the location of the true lumen. Aortic dilation was defined as thoraco-abdominal aortic expansion ≥5 mm on 1-year postoperative computed tomography images.

RESULTS

We examined 49 surgical patients who were assigned to the ventral (n = 22) and dorsal (n = 27) groups. The number of patients with ≥5 mm thoraco-abdominal aortic dilation after the operation was significantly higher in the ventral group than in the dorsal group (90.9% vs 51.9%, P = 0.009). The multivariable logistic regression analysis showed that the ventral type was an independent prognostic factor for thoraco-abdominal aortic dilation after the operation (odds ratio, 6.01; 95% confidence interval, 1.56-23.77; P = 0.009).

CONCLUSIONS

The location of the true lumen of the abdominal aorta in acute type A aortic dissection may be a prognostic factor for thoraco-abdominal aortic dilation after surgical repair.

Fenestrated and covered frozen elephant trunk technique for management of chronic aortic dissection

BACKGROUND

Reintervention for residual dissection after repaired type A aortic dissection remains challenging. When a frozen elephant trunk (FET) is used, the incidence of distal stent graft-induced new entry (d-SINE) is reportedly high in chronic dissection.

AIMS

We report a case of successful redo arch repair using fenestrated and covered FET techniques for chronic residual aortic dissection.

METHODS

After the arch was transected proximal to the left subclavian artery (LSCA), and a modified FET prosthesis, in which the distal edge of the FET was covered, was deployed. A fenestration was created in the FET on the LSCA aspect.

RESULTS

The postoperative course was uneventful.

DISCUSSION

The distal edge of the FET was covered to prevent d-SINE. Creation of a fenestration on the FET eliminates the need to reconstruct the LSCA.

CONCLUSION

The fenestrated FET technique simplifies redo arch repair and the covered FET technique can potentially prevent d-SINE.

Metabolic syndrome and heart failure: 40 years follow up results of the Seven Countries Study

Introduction

Metabolic syndrome (Met Sy) as a highly debatable cluster of traditional risk factors is known to promote cardiometabolic-related morbidity and mortality, but its precise mechanisms remain to be determined.

Purpose

We sought to determine influence of MetSy on heart failure (HF) morbidity and mortality in the Seven Countries' Study as one of the oldest epidemiological studies.

Methods

The Seven Countries Study encompassed 12,763 participants from 3 continents who were all healthy men of over 40 years at baseline and who underwent regular check ups every 5 years throughout over a 4 decades' span. Morbidity and mortality was adjudicated according to valid ICD and LPH coding.

Results

Using the IDF definition of the Metabolic Syndrome, 9,09% of participants were identified (Figure 1). HF was confirmed in 220 patients (16.4% alive at 40y follow up visit), while 8.2% died of HF as well in the same time-frame (Tables 1 & 2). Presence of MetSy has been shown to significantly influence HF mortality (Figures 2) with lowest survival of 22% for 300 months of follow up for patients with both MetSy and HF (Log rank test=4.405, p<0.0001).

Conclusion

Metabolic syndrome treatment remains in the realm of risk factors' control that now we know influence both ischemic heart disease and heart failure of other origins. Historically, just emerging biomarkers' and targeted imaging weren't available to determine such at the time of HF diagnosis. Also, the sample consisted of men only, mainly Caucasian and a modest proportion of Asian and African-American now known to carry ethnic-specific burden of cardiovascular disease. All of the above, emphasizes the importance of more diversity, equity and inclusion-dedicated long term both observational, as well as interventional research.

Funding Acknowledgement

Type of funding sources: None.

Effects of a frozen elephant trunk on postoperative renal dysfunction in acute type A aortic dissection extending into the renal artery

BACKGROUND

We investigated the effects of frozen elephant trunk (FET) implantation on clinical outcomes in patients with acute type A aortic dissection (ATAAD) extending into the renal artery (RA).

METHODS

Between May 2016 and April 2021, 136 patients underwent surgery for ATAAD at our hospital. Patients who died within 7 days postoperatively and those without preoperative contrast-enhanced computed tomography (CT) data were excluded from the study. The remaining 125 patients were included in this study. A preoperative CT-documented RA abnormality was found in 53 patients. Clinical outcomes, including renal dysfunction and CT findings, were compared between 29 patients with and 24 patients without the FET prosthesis.

RESULTS

Among the 53 patients with RA abnormalities, origin of the RA from the false lumen was the most common type of abnormality. The percentage of men and rate of arch repair were higher, and the operation, cardiopulmonary bypass, and lower body hypothermic circulatory arrest times were longer in the FET than in the non-FET group. Early mortality rates were similar between groups. The incidence of postoperative acute kidney injury (AKI) was lower in the FET group (35% vs. 67%, p = 0.028). Multivariable analysis showed that FET implantation was associated with a low incidence of AKI (odds ratio: 0.28, 95% confidence interval: 0.08-0.96; p = 0.043). Among the 125 patients with or without RA abnormalities, no predictor of AKI was identified.

CONCLUSION

FET implantation protected against postoperative AKI in patients with ATAAD extension into the RA.

Reconstruction of the left subclavian artery in arch repair: An end-to-side anastomosis technique

BACKGROUND

The left subclavian artery (LSCA) is deeply located and difficult to visualize in some cases of total arch replacement.

AIMS

We report an end-to-side anastomosis technique that enables safer and easier anatomical reconstruction of the LSCA.

MATERIALS AND METHODS

Under Hypothermic circulatory arrest, the origin of the LSCA was ligated and pulled caudally. With clamping the distal LSCA, a graft was anastomosed to the anterior wall of the LSCA and antegrade cerebral perfusion to the LSCA was ensured through the anastomosed graft. Thereafter, distal anastomosis was performed proximal to the LSCA.

RESULTS

The postoperative course was uneventful.

DISCUSSION

Our reconstruction technique provides excellent exposure of the LSCA by pulling the origin of the LSCA caudally. Hemostasis after reconstruction is feasible, as the anastomosis in the anterior wall of the LSCA is easily visualized.

CONCLUSION

The end-to-side anastomosis technique for LSCA reconstruction is a simple alternative in arch repair.

OUP accepted manuscript

Distal stent graft-induced new entry is not rare after frozen elephant trunk implantation. We report a case of covered frozen elephant trunk placement for prevention of distal stent graft-induced new entry. Coverage of the rigid distal stent edge using a graft reduces mechanical stress on the intima and radial force of the distal stent; therefore, this technique can potentially prevent distal stent graft-induced new entry.

Influence of residual primary entry following the tear-oriented strategy for acute type A aortic dissection

OBJECTIVES

Although a tear-oriented strategy has contributed to improving short-term surgical outcomes of acute type A aortic dissection (ATAAD), long-term clinical influences of residual entry tear in the downstream aorta have not been fully investigated. The goal of this study was to assess the long-term surgical outcomes of ATAAD with or without a residual entry tear in the downstream aorta.

METHODS

Medical records of 1107 patients with ATAAD who underwent emergency surgery between 1990 and 2018 were retrospectively reviewed. A tear-oriented paradigm was adopted for the baseline strategy. The 837 patients in whom the entry tears were resected comprised the resected group, and the 270 patients with a residual entry tear comprised the residual group. Of these patients, 252 in each group were analysed using propensity score matching, and long-term outcomes were compared with or without residual entry.

RESULTS

Hospital deaths were lower in the resected group (3.2% vs 8.3%; P = 0.020). The survival rate was not significantly different between the groups: It was 83.8% and 68.5% in the resected group and 80.2% and 66.5% in the residual group at 5 and 10 years, respectively (P = 0.600). However, residual entry in the downstream aorta affected the distal aortic event-free survival rate (90.4% and 80.6% in the resected group and 82.3% and 67.4% in the residual group at 5 and 10 years, respectively; P = 0.003). Furthermore, multivariable risk analysis of 1107 patients confirmed that a residual entry in the downstream aorta was a risk factor for distal aortic events.

CONCLUSIONS

The tear-oriented strategy remains the gold standard for high-risk patients; however, the extensive operation might be considered for stable patients to reduce long-term aortic events.

Bail-Out Pull-Through Pull-Back Technique for Accidental Coverage of the Left Common Carotid Artery During Thoracic Endovascular Aortic Repair

PURPOSE

We describe a pull-through pull-back technique to revascularize the left common carotid artery (LCCA) that was unintentionally covered during thoracic endovascular aortic repair (TEVAR).

CASE REPORT

A 69-year-old man presented with back pain secondary to acute type B aortic dissection with an intimal tear in the proximal descending aorta. Serial computed tomography (CT) revealed an enlarged descending aorta and proximal progression of the aortic dissection. He underwent left carotid-subclavian artery bypass and TEVAR, 10 days after admission. The Valiant Navion stent graft without a bare stent was deployed proximally; however, the LCCA was unintentionally covered by the stent graft during this procedure. A pull-through form was created between the left axillary and femoral arteries using a 0.035-inch guide wire. The pull-through guide wire was gently pulled, and the greater curvature of the proximal end of the stent graft was displaced distally. Angiography confirmed restoration of antegrade blood flow into the LCCA. The patient's postoperative course was uneventful. Follow-up CT performed 6 months postoperatively confirmed preserved blood flow into the LCCA without endoleak nor stent migration.

CONCLUSION

The pull-through pull-back technique is a feasible troubleshooting strategy for accidental coverage of supra-aortic vessels during TEVAR.

Clinical outcomes of a fenestrated frozen elephant trunk technique for acute type A aortic dissection

OBJECTIVES

We investigated the outcomes of a fenestrated frozen elephant trunk (FET) technique performed without reconstruction of one or more supra-aortic vessels for aortic repair in patients with acute type A aortic dissection.

METHODS

We investigated 22 patients who underwent the fenestrated FET technique for acute type A aortic dissection at our hospital between December 2017 and April 2020. The most common symptom was chest pain and/or back pain. Nine patients presented with malperfusion and 1 with cardiac arrest, preoperatively. A FET was deployed under hypothermic circulatory arrest and manually fenestrated under direct vision. Single fenestration was made in the FET in 15 patients, 2 fenestrations in 5 patients and a total fenestrated technique in 2 patients. Concomitant procedures were performed in 5 patients.

RESULTS

The cardiopulmonary bypass, aortic cross-clamp and hypothermic circulatory arrest times were 181 ± 49, 106 ± 43 and 37 ± 7 min, respectively. In-hospital mortality, stroke, or recurrent nerve injury did not occur in any patient. One patient developed paraparesis, which completely recovered at discharge. During the follow-up period (mean 18 ± 7 months), 1 patient died of heart failure. Fenestration site occlusion did not occur. Follow-up computed tomography (mean 12 ± 6 months postoperatively) revealed that the maximal aortic diameter remained unchanged at the levels of the distal end of the FET, the 10th thoracic vertebra and the coeliac artery; however, the aortic diameter was significantly reduced at the level of the pulmonary artery bifurcation.

CONCLUSIONS

The fenestrated FET technique is a simple, safe and effective procedure for selected patients with acute type A aortic dissection.

Metabolic syndrome and mortality prediction in the seven countries' study: single or multifactorial

Introduction

The metabolic syndrome (Met Sy) is a known cluster of risk factors (HTA, HLP, DM, BMI) that promotes overall vascular disease, however its real impact on overall, ischemic heart disease (IHD) and cerebrovascular disease (CVD) mortality remains debated.

Material and methods

The Seven Countries Study encompassed 12,763 participants who were healthy men over 40y at baseline and who underwent regular check ups every 5 years throughout over a 4 decades' span. Morbidity and mortality was adjudicated according to valid ICD and LPH coding.

Results

Using the IDF definition of the Metabolic Syndrome, 9,09% of participants were identified. In a multivariate analysis predictors for overall Mt were hypertension (p<0.0001) and BMI (p<0.029), while HLP had a weak prediction value (p=0.083), where as MetSy and DM had not at all. Hypertension (p<0.0001) remained a strong predictor for IHD mortality together with HLP (p<0.0001), while diabetes was of weak predictive value (p=0.065), whereas MetSy failed to. Although HTA was a strong predictor for CVD mortality, so did MetSy (p<0.050), while DM and HLP haven't while BMI had a low impact (p=0.070).

Conclusion

Metabolic syndrome's role in atherosclerotic burden remains important, however whether its power is due to its respective components or their interactions remains to be an issue. The described results belong to an era where both IHD and CVD were considered a “male disease” women were spared of, so, further validation in the described cohorts is needed in an offspring fashion, however hypertension remains the driving force of both overall mortality as well as specific IHD and CVD ones, also previously demonstrated in the very same cohort to be more important in the setting of maternal family history of hypertension, than paternal one.

MetSy in the SCS

Funding Acknowledgement

Type of funding source: None

Double-patch and glue repair of a postinfarction left ventricular pseudoaneurysm

An 85-year-old man with appetite loss, lightheadedness, and leg edema was referred to our institution. Computed tomography and transthoracic echocardiography revealed a left ventricular pseudoaneurysm with a maximal diameter of 80 mm and severe mitral regurgitation. Coronary angiography showed 90% stenosis and total occlusion of the left circumflex artery at segments 11 and 12, respectively. He was diagnosed with postinfarction left ventricular pseudoaneurysm and underwent patch repair using two bovine pericardium patches and biological glue, mitral valve replacement, and coronary artery bypass grafting. His postoperative course was uneventful.

Clinical outcome of acute thoracic aortic syndrome in nonagenarians

BACKGROUND

Decision-making regarding the operability of thoracic aortic disease in nonagenarian patients remains controversial because outcomes of open surgical repair of the thoracic aorta are unclear. We investigated the surgical and nonsurgical outcomes of acute thoracic aortic syndrome treatment in nonagenarians.

METHODS

After evaluating data in our institute from April 2016 to March 2020, we included 10 nonagenarians who needed surgical intervention on the thoracic aorta via a median sternotomy for acute thoracic aortic syndrome. The mean age of the cohort was 91.9 ± 2.1 years. Five patients underwent open surgical repair of the thoracic aorta (surgical group), and 5 refused surgery (nonsurgical group). All patients in the surgical group performed activities of daily living independently, with a mean clinical frailty scale of 3.2 ± 0.4. The surgical group included 4 patients with type A aortic dissection and one with a ruptured thoracic aortic aneurysm. Hemiarch replacement was performed in 3 patients and total arch replacement in 2. The mean follow-up period was 17.8 ± 5.1 months.

RESULTS

Hospital mortality rates were 0% in the surgical and 80% in the nonsurgical group. The mean length of hospitalization was 28.4 ± 6.7 days in the surgical group. The 1-year survival rates were 100% in the surgical group and 20% in the nonsurgical group.

CONCLUSION

Open surgical repair for acute thoracic aortic syndrome via median sternotomy is a reasonable treatment option even in nonagenarians. Involvement of family members is important for decision-making to devise the optimal treatment strategy (surgical vs. medical).

Predictors of Cerebral Aneurysm Rupture after Coil Embolization: Single-Center Experience with Recanalized Aneurysms

BACKGROUND AND PURPOSE

Recanalization after coil embolization is widely studied. However, there are limited data on how recanalized aneurysms rupture. Herein, we describe our experience with the rupture of recanalized aneurysms and discuss the type of recanalized aneurysms at greatest rupture risk.

MATERIALS AND METHODS

A total of 426 unruptured aneurysms and 169 ruptured aneurysms underwent coil embolization in our institution between January 2009 and December 2017. Recanalization occurred in 38 (8.9%) of 426 unruptured aneurysms (unruptured group) and 37 (21.9%) of 169 ruptured aneurysms (ruptured group). The Modified Raymond-Roy classification on DSA was used to categorize the recanalization type. Follow-up DSA was scheduled until 6 months after treatment, and follow-up MRA was scheduled yearly. If recanalization was suspected on MRA, DSA was performed.

RESULTS

In the unruptured group, the median follow-up term was 74.0 months. Retreatment for recanalization was performed in 18 aneurysms. Four of 20 untreated recanalized aneurysms (0.94% of total coiled aneurysms) ruptured. In untreated recanalized aneurysms, class IIIb aneurysms ruptured significantly more frequently than class II and IIIa (P = .025). In the ruptured group, the median follow-up term was 28.0 months. Retreatment for recanalization was performed in 16 aneurysms. Four of 21 untreated recanalized aneurysms (2.37% of total coiled aneurysms) ruptured. Class IIIb aneurysms ruptured significantly more frequently than class II and IIIa (P = .02).

CONCLUSIONS

The types of recanalization after coil embolization may be predictors of rupture. Coiled aneurysms with class IIIb recanalization should undergo early retreatment because of an increased rupture risk.

Incidence of postoperative atrial fibrillation in transdermal β-blocker patch users is lower than that in oral β-blocker users after cardiac and/or thoracic aortic surgery

OBJECTIVE

Postoperative atrial fibrillation (POAF) after open heart surgery is associated with a high risk of mortality and morbidity. Although oral β-blockers are usually recommended to prevent POAF, the efficacy of a transdermal β-blocker patch in preventing POAF is unclear. We compared the incidence of POAF between users of oral and transdermal bisoprolol.

METHODS

We investigated 108 patients who underwent cardiac and/or thoracic aortic surgery between April 2016 and February 2018. We compared perioperative clinical and hemodynamic variables between 49 patients treated with a transdermal bisoprolol patch and 59 patients treated with an oral bisoprolol fumarate.

RESULTS

POAF occurred in 24% of patients in the transdermal and in 46% of patients in the oral bisoprolol groups (p = 0.027). No intergroup difference was observed in in-hospital mortality, perioperative blood pressures and heart rates, and other morbidities. Multivariable logistic regression analysis revealed that the use of transdermal bisoprolol was independently associated with a lower rate of POAF (odds ratio 0.21, 95% confidence interval 0.05-0.84, p = 0.027).

CONCLUSIONS

A transdermal bisoprolol patch is an effective and safe β-blocker drug delivery system. The incidence of POAF in this group was lower than that in users of oral bisoprolol.

Postinfarction right ventricular wall dissection with left-to-right shunting

Ventricular septal rupture is an uncommon fatal complication of acute myocardial infarction. In rare cases, the rupture can extend into the right ventricular free wall and cause intramyocardial dissection. We describe the case of a patient who developed postinfarction right ventricular free wall dissection with left-to-right shunting and successfully underwent patch repair.

Feasibility of low-frequency ultrasound imaging using pulse compressed parametric ultrasound

When using high-frequency (HF) ultrasound in sonography, attenuation due to the viscosity of the medium limits the available imaging depth, and strong reflection and scattering from hard tissue, such as bone, render biological diagnosis very difficult. In order to resolve these problems, the feasibility of low-frequency (LF) parametric ultrasound imaging with high directivity was explored in the present study. A pulse compression technique was applied to chirp-modulated parametric ultrasound waves in the frequency band of 100-500 kHz generated from modulated primary ultrasound waves with a center frequency of 2.8 MHz in order to improve the signal-to-noise ratio (SNR). Low-frequency ultrasound images of brass rods obtained using pulse compressed parametric ultrasound exhibit accurate target distances, a 3-mm range resolution, which agrees well with the theoretical value, and an 8-dB improvement in SNR. Parametric ultrasound imaging with pulse compression makes easy to separate overlapping targets in comparison with HF ultrasound imaging, and indicates the image with brightness independent of distance in comparison with directly radiated LF ultrasound imaging. These results reveal that pulse compressed LF parametric ultrasound is not only a useful method for improving the SNR and providing accurate distance measurements, but also enables imaging of overlapping targets.

Gene expression profiling of acute type A aortic dissection combined with in vitro assessment

OBJECTIVES

The mechanisms underlying aortic dissection remain to be fully elucidated. We aimed to identify key molecules driving dissection through gene expression profiling achieved by microarray analysis and subsequent in vitro experiments using human aortic endothelial cells (HAECs) and aortic vascular smooth muscle cells (AoSMCs).

METHODS

Total RNA, including microRNA (miRNA), was isolated from the intima-media layer of dissected ascending aorta obtained intraoperatively from acute type A aortic dissection (ATAAD) patients without familial thoracic aortic disease (n = 8) and that of non-dissected ascending aorta obtained from transplant donors (n = 9). Gene expression profiling was performed with mRNA and miRNA microarrays, and results were confirmed by quantitative polymerase chain reaction (qPCR). Target genes and miRNA were identified by gene ontology analysis and a literature search. To reproduce the in silico results, HAECs and AoSMCs were stimulated in vitro by upstream cytokines, and expression of target genes was assessed by qPCR.

RESULTS

Microarray analysis revealed 1536 genes (3.6%, 1536/42 545 probes) and 41 miRNAs (3.0%, 41/1368 probes) that were differentially expressed in the ATAAD group (versus donor group). The top 15 related pathways included regulation of inflammatory response, growth factor activity and extracellular matrix. Gene ontology analysis identified JAK2 (regulation of inflammatory response), PDGFA, TGFB1, VEGFA (growth factor activity) and TIMP3, TIMP4, SERPINE1 (extracellular matrix) as the target genes and miR-21-5p, a TIMP3 repressor, as target miRNA that interacts with the target genes. Validation qPCR confirmed the altered expression of all 7 target genes and miR-21-5p in dissected aorta specimens (all genes, P < 0.05). Ingenuity pathway analysis showed TNF-α and TGF-β to be upstream cytokines for the target genes. In vitro experiments showed these cytokines inhibit TIMP3 expression (P < 0.05) and enhance VEGFA expression (P < 0.01) in AoSMCs but not HAECs. miR-21-5p expression increases in AoSMCs under TNF-α and TGF-β stimulation (fold change: 1.36; P = 0.011).

CONCLUSIONS

Results of our novel approach, integrating in vitro assessment into gene expression profiling, implicated chronic inflammation characterized by MMP-TIMP dysregulation, increased VEGFA expression, and TGF-β signalling in the development of dissection. Further investigation may reveal novel diagnostic biomarkers and uncover the mechanism(s) underlying ATAAD.

Early and mid-term outcomes of endovascular and open surgical repair of non-dissected aortic arch aneurysm†

OBJECTIVES

With the introduction of endovascular stent graft technology, a variety of surgical options are available for patients with aortic aneurysms. We sought to evaluate early-term and mid-term outcomes of patients undergoing endovascular and open surgical repair for non-dissected aortic arch aneurysm.

METHODS

Overall, 200 patients underwent treatment for isolated non-dissected aortic arch aneurysm between January 2008 and February 2016: 133 patients had open surgery and 67, endovascular repair. Early-term and mid-term outcomes were compared.

RESULTS

Seventy percent ( n  = 47) needing endovascular repair underwent fenestrated stent graft and 30% ( n  = 20) underwent the debranched technique. Patients in the open surgery group were younger (71 vs 75 years, P  < 0.001) and had a lower prevalence of ischaemic heart disease (11% vs 35%, P  < 0.001). Intensive care unit stay (1 vs 3 days, P  < 0.001), hospital stay (11 vs 17 days, P  < 0.001) and surgical time (208 vs 390 min, P  < 0.001) were lower in the endovascular repair group than in the open surgery group. There were 3 in-hospital deaths each in the open surgery and endovascular groups (2% vs 5%, respectively, P  = 0.40). Mid-term survival ( P  < 0.001) and freedom from reintervention ( P  = 0.009) were better in the open surgery than in the endovascular repair group. No aneurysm-related deaths were observed. The propensity-matched comparison ( n  = 58) demonstrated that survival was better in the open surgery group ( P  = 0.011); no significant difference was seen in the reintervention rate ( P  = 0.28).

CONCLUSIONS

Close follow-up for re-intervention may reduce the risk for aneurysm-related deaths and provide acceptable outcomes in patients undergoing endovascular repair.

Pulmonary Stenosis Caused by Ductus Arteriosus Aneurysm: A Case Report

A 76-year-old woman with a 2-week history of dyspnea on exertion was admitted to our hospital. A computed tomography scan showed a 70-mm diameter aortic arch aneurysm containing a large thrombus that was compressing the pulmonary artery. Echocardiography showed severe pulmonary stenosis and no shunt flow. Operative findings revealed an aneurysmal thrombus protruding into the lumen of the pulmonary artery through a foramen. A ductus arteriosus aneurysm was diagnosed. After the thrombus removal, arch replacement and ductus closure with a prosthetic patch were performed. Histological examination showed that the thrombus had no vascular components. The patient’s symptoms were relieved, and she was discharged.

Opsin 3 and 4 mediate light-induced pulmonary vasorelaxation that is potentiated by G protein-coupled receptor kinase 2 inhibition

We recently demonstrated that blue light induces vasorelaxation in the systemic mouse circulation, a phenomenon mediated by the nonvisual G protein-coupled receptor melanopsin (Opsin 4; Opn4). Here we tested the hypothesis that nonvisual opsins mediate photorelaxation in the pulmonary circulation. We discovered Opsin 3 (Opn3), Opn4, and G protein-coupled receptor kinase 2 (GRK2) in rat pulmonary arteries (PAs) and in pulmonary arterial smooth muscle cells (PASMCs), where the opsins interact directly with GRK2, as demonstrated with a proximity ligation assay. Light elicited an intensity-dependent relaxation of PAs preconstricted with phenylephrine (PE), with a maximum response between 400 and 460 nm (blue light). Wavelength-specific photorelaxation was attenuated in PAs from Opn4^-/- mice and further reduced following shRNA-mediated knockdown of Opn3. Inhibition of GRK2 amplified the response and prevented physiological desensitization to repeated light exposure. Blue light also prevented PE-induced constriction in isolated PAs, decreased basal tone, ablated PE-induced single-cell contraction of PASMCs, and reversed PE-induced depolarization in PASMCs when GRK2 was inhibited. The photorelaxation response was modulated by soluble guanylyl cyclase but not by protein kinase G or nitric oxide. Most importantly, blue light induced significant vasorelaxation of PAs from rats with chronic pulmonary hypertension and effectively lowered pulmonary arterial pressure in isolated intact perfused rat lungs subjected to acute hypoxia. These findings show that functional Opn3 and Opn4 in PAs represent an endogenous "optogenetic system" that mediates photorelaxation in the pulmonary vasculature. Phototherapy in conjunction with GRK2 inhibition could therefore provide an alternative treatment strategy for pulmonary vasoconstrictive disorders.