human
***task***
the task is to summarize an input biomedical literature in six sentences

***input***
the input is a biomedical literature

***output***
the output is the summary of an input biomedical literature in six sentences

***documentation***

***examples***

input: over the past decades , improvements have been made in the design and hemodynamics of mechanical valve prostheses in order to reduce valve dysfunction and increase durability . however , prosthetic stenosis due to thrombus or pannus is still one of the most frequent complications and it can be severe , evolving into cardiogenic shock . pannus is a non - immune inflammatory reaction of the body to the valve prosthesis , a proliferation of fibroelastic tissue and collagen , with a starting point in the suture area and subacute or chronic centripetal evolution . it usually proliferates on the ventricular side of aortic prostheses and is associated with certain risk factors such as operative technique , characteristics of the prosthesis , size of valves in patients with a small valve ring , young age , female sex , pregnancy , low cardiac output , turbulent flow , infection , inadequate anticoagulation . the differential diagnosis of pannus - related prosthetic valve dysfunction with other causes of prosthetic valve dysfunction , mainly thrombotic involvement , is frequently difficult but essential , because therapeutic approaches are different . a 54 - year - old patient from an urban area was brought by the ambulance to the service of cardiology for typical angina pain with onset about an hour before , after effort , without remission following nitroglycerin administration , associated with profuse sweating , nausea and vomiting . we mention that the patient was known to the service of cardiology , as he had had a mechanical aortic prosthesis in place for 14 years , for aortic stenosis of rheumatic cause on a bicuspid valve , and ascending aortic aneurysm . the patient was last evaluated 3 years before , under the conditions of a similar angina episode , interpreted as non - st segment elevation myocardial infarction ( nstemi ) syndrome , investigated by coronarography , with angiographically normal coronary arteries . at that time , echocardiography evidenced increased transprosthetic gradients : maximum pressure gradient ( maxg ) = 88 mmhg , mean pressure gradient ( meang ) = 50 mmhg ( normofunctional prosthesis range : 20 mmhg ) , maximum velocity ( vmax ) = 4 m / sec ( normofunctional prosthesis range : 3 m / sec ) , a moderate mismatch - indexed aortic valve orifice area = 0.82 cm2 / m2 ( moderate mismatch range : 0.650.85 cm2 / m2 ) , and a small size mass with a pannus appearance on the ventricular side of the prosthesis , which did not interfere with the disc movement . the current episode occurred in the context of repeated chest pain episodes over the past month , which were of lower intensity compared to the current episode , with a variable duration , during effort and rest , with spontaneous remission , accompanied by a decreased effort tolerance , the patient being asymptomatic until one month before . daily medication at home consisted of oral anticoagulant ( international normalized ratio ( inr ) values unchecked for the past 2 months ) , aspirin , converting enzyme inhibitor . objectively , the patient at admission was afebrile , dyspneic , with angina , blood pressure of 90/50 mmhg , ventricular rate of 70 / min , audible prosthetic murmur , no pathological pulmonary changes , diffuse subendocardial injury on electrocardiogram ( ecg ) ( figure 1 ) , emergency echocardiography : non - dilated left ventricle , with preserved ejection fraction , without significant regional kinetic disorders , dilated ascending aorta , without signs of dissection within 2 cm , increased transprosthetic gradients , biologically : unreacted myocardial enzymes in the first set ( ck = 142 ui / l , normal range : 10190ui / l ; ck - mb = 18 ui / l , normal range : 025 ui / l ) , normal aspartate aminotransferase ( asat ) ( 17 ui / l , normal range : 540 ui / l ) , alanin aminotransferase ( alat ) ( 17 ui / l , normal range : 541ui / l ) , leukocytosis ( 12.42 * 103 / l , normal range : 4.09.0 * 103 / l ) , hyperglycemia ( 215 mg / dl , normal range : 74106 mg / dl ) , inr value of 2.04 ( therapeutic range : 23 ) . coronarography evidenced a normal appearance of epicardial coronary arteries , similarly to previous coronarography , and an ample movement of the prosthetic disc . aortic dissection was excluded by ct angiography ( cta ) , infectious endocarditis and myocarditis were excluded clinically , biologically , echocardiographically . gated single - photon emission computerized tomography ( spect ) with technetium ( tc ) - 99 m evidenced hypokinesis of the inferior wall and of the interventricular septum , without perfusion defects or non - viable areas . with anticoagulant , anti - aggregant , calcium blocker , antiarrhythmic treatment during hospitalization , the patient continued to present frequent pain episodes of very high intensity , which were relieved by major analgesics or sometimes remitted spontaneously , accompanied by reversible ecg changes ( figures 2 and 3 ) . myocardial enzymes were reacted ( peak values : ck - mb = 318.9 ui / l ; ck = 2755 ui / l ; troponine i = 2.59 ng / ml ( normal range : 0.014 ng / ml ) , ast = 243 ui / l , alt = 47repeated transthoracic echocardiography ( tte ) was performed , which evidenced increased transprosthetic gradients consistent with severe aortic stenosis ( maxg = 7092.7 mmhg , meang = 3855.5 mmhg , vmax = 4.24.9 m / sec , aortic regurgitation ( ar ) grade ii due to intraprosthetic leak ) , moderate prosthesis - patient mismatch ( 0.670.8 cm2 / m2 ) , intermittent kinetic disorders in the inferior territory , and an echodense mass attached to the ventricular side of the prosthesis . subsequently , transesophageal echocardiography ( toe ) was performed , which allowed to visualize the interference of the mass with the closure of the prosthetic disc ( figure 4 ) . the patient was transferred to the service of cardiovascular surgery , where the stenosing subvalvular mass with a macroscopic pannus appearance , subsequently confirmed by microscopy ( figure 5 ) , was surgically removed in extracorporeal circulation . postoperative evolution ( at 2 months ) was favorable , without the recurrence of pain complaints and the restoration of effort tolerance . tte showed an improvement of transprosthetic gradients : maxg = 55 mmhg , meang = 28 mmhg , vmax = 3.7 m / sec , with the persistence of ar grade ii , hemodynamic insignificant . the discordance between repeated severe symptoms , ecg and enzymatic changes on the one hand , and the coronarographic and particularly , scintigraphic appearance on the other hand should be mentioned . normal coronarographic appearance does not exclude the presence of endothelial erosions visible by intracoronary imaging methods such as intravascular ultrasound ( ivus ) or optical coherence tomography ( oct ) , methods that were not applied in this case . coronary spasm can not be excluded , but there are several counter - arguments : it is frequently accompanied by st segment elevation , it was not evidenced during coronarography , a procedure performed during the crisis , no response to anticalcium drugs . what was intriguing and made the diagnosis of infarction difficult was the almost white scintigraphic result , suggesting that the event that induced the enzymatic increase left no visible traces on scintigraphy . transient kinetic disorders evidenced by some echocardiograms and by scintigraphy raised questions : interoperative variability or post - ischemic myocardial stunning . while excluding other possible cardiovascular diseases and taking into consideration prosthetic valve dysfunction , which was the only abnormality found , with the remission of symptoms post - intervention , final differential diagnosis was required between the various causes of increased transprosthetic gradients : stenosis due to pannus and / or thrombus , prosthesis - patient mismatch ( moderate , previously documented ) . differential diagnosis between thrombus and pannus is made based on clinical , echocardiographic and morphopathological criteria ( table i ) and is essential because therapeutic approaches are different . if in thrombotic obstruction , thrombolysis can be considered , this is contraindicated in the case of pannus , where the only valid therapeutic option is surgery ( valve replacement or pannus removal ) . in our case , pannus was supported by chronic evolution , effective anticoagulation , subvalvular location at the level of the aortic prosthesis , non - interference with the opening of the prosthetic disc . in contrast , the acute evolution of symptoms , with frequent episodes occurring during rest , under the conditions of transprosthetic gradients approximately similar to those determined 3 years before , was not characteristic of uncomplicated pannus . a possible thrombotic association , with repeated microembolizations , in the absence of imaging or morphopathological evidence , remained hypothetical . therapeutic approach in case of severe stenosis due to pannus involves surgical reintervention , consisting of valve replacement or pannus removal . valve replacement , a more complex procedure , is recommended only in certain conditions such as extensive circumferential pannus or a significantly altered prosthesis , based on the assumption of a marked inflammatory reaction in the case of replacement . in this case , an alternative could have been replacement with a larger size prosthesis , possibly with the previous enlargement of the aortic ring , and / or a newer generation prosthesis , with intrinsically reduced transprosthetic gradients . in conclusion , the presented case illustrates the problems that pannus - related prosthetic valve dysfunction , a late complication of mechanical prosthetic valve replacement , can pose in terms of clinical picture ( severity , discordant elements ) , differential diagnosis , as well as optimal therapeutic approach .
output:

agent
pannus - related prosthetic valve dysfunction , a complication of mechanical prosthetic valve replacement , is rare , with a slowly progressive evolution , but it can be acute , severe , requiring surgical reintervention . we present the case of a patient with a mechanical single disc aortic prosthesis , with moderate prosthesis - patient mismatch , minor pannus found on previous ultrasound examinations , who presented to our service with angina pain with a duration of 1 hour , subsequently interpreted as non - st segment elevation myocardial infarction ( nstemi ) syndrome . coronarography showed normal epicardial coronary arteries , an ample movement of the prosthetic disc , without evidence of coronary thromboembolism , and gated single - photon emission computerized tomography ( spect ) with technetium ( tc ) - 99 m detected no perfusion defects . transthoracic echocardiography ( tte ) evidenced a dysfunctional prosthesis due to a subvalvular mass ; transesophageal echocardiography ( toe ) showed the interference of this mass , with a pannus appearance , with the closure of the prosthetic disc . under conditions of repeated angina episodes , under anticoagulant treatment , surgery was performed , with the intraoperative confirmation of pannus and its removal . postoperative evolution was favorable . this case reflects the diagnostic and therapeutic management problems of pannus - related prosthetic valve dysfunction .
***task***
the task is to summarize an input biomedical literature in six sentences

***input***
the input is a biomedical literature

***output***
the output is the summary of an input biomedical literature in six sentences

***documentation***

***examples***

input: over the past decades , improvements have been made in the design and hemodynamics of mechanical valve prostheses in order to reduce valve dysfunction and increase durability . however , prosthetic stenosis due to thrombus or pannus is still one of the most frequent complications and it can be severe , evolving into cardiogenic shock . pannus is a non - immune inflammatory reaction of the body to the valve prosthesis , a proliferation of fibroelastic tissue and collagen , with a starting point in the suture area and subacute or chronic centripetal evolution . it usually proliferates on the ventricular side of aortic prostheses and is associated with certain risk factors such as operative technique , characteristics of the prosthesis , size of valves in patients with a small valve ring , young age , female sex , pregnancy , low cardiac output , turbulent flow , infection , inadequate anticoagulation . the differential diagnosis of pannus - related prosthetic valve dysfunction with other causes of prosthetic valve dysfunction , mainly thrombotic involvement , is frequently difficult but essential , because therapeutic approaches are different . a 54 - year - old patient from an urban area was brought by the ambulance to the service of cardiology for typical angina pain with onset about an hour before , after effort , without remission following nitroglycerin administration , associated with profuse sweating , nausea and vomiting . we mention that the patient was known to the service of cardiology , as he had had a mechanical aortic prosthesis in place for 14 years , for aortic stenosis of rheumatic cause on a bicuspid valve , and ascending aortic aneurysm . the patient was last evaluated 3 years before , under the conditions of a similar angina episode , interpreted as non - st segment elevation myocardial infarction ( nstemi ) syndrome , investigated by coronarography , with angiographically normal coronary arteries . at that time , echocardiography evidenced increased transprosthetic gradients : maximum pressure gradient ( maxg ) = 88 mmhg , mean pressure gradient ( meang ) = 50 mmhg ( normofunctional prosthesis range : 20 mmhg ) , maximum velocity ( vmax ) = 4 m / sec ( normofunctional prosthesis range : 3 m / sec ) , a moderate mismatch - indexed aortic valve orifice area = 0.82 cm2 / m2 ( moderate mismatch range : 0.650.85 cm2 / m2 ) , and a small size mass with a pannus appearance on the ventricular side of the prosthesis , which did not interfere with the disc movement . the current episode occurred in the context of repeated chest pain episodes over the past month , which were of lower intensity compared to the current episode , with a variable duration , during effort and rest , with spontaneous remission , accompanied by a decreased effort tolerance , the patient being asymptomatic until one month before . daily medication at home consisted of oral anticoagulant ( international normalized ratio ( inr ) values unchecked for the past 2 months ) , aspirin , converting enzyme inhibitor . objectively , the patient at admission was afebrile , dyspneic , with angina , blood pressure of 90/50 mmhg , ventricular rate of 70 / min , audible prosthetic murmur , no pathological pulmonary changes , diffuse subendocardial injury on electrocardiogram ( ecg ) ( figure 1 ) , emergency echocardiography : non - dilated left ventricle , with preserved ejection fraction , without significant regional kinetic disorders , dilated ascending aorta , without signs of dissection within 2 cm , increased transprosthetic gradients , biologically : unreacted myocardial enzymes in the first set ( ck = 142 ui / l , normal range : 10190ui / l ; ck - mb = 18 ui / l , normal range : 025 ui / l ) , normal aspartate aminotransferase ( asat ) ( 17 ui / l , normal range : 540 ui / l ) , alanin aminotransferase ( alat ) ( 17 ui / l , normal range : 541ui / l ) , leukocytosis ( 12.42 * 103 / l , normal range : 4.09.0 * 103 / l ) , hyperglycemia ( 215 mg / dl , normal range : 74106 mg / dl ) , inr value of 2.04 ( therapeutic range : 23 ) . coronarography evidenced a normal appearance of epicardial coronary arteries , similarly to previous coronarography , and an ample movement of the prosthetic disc . aortic dissection was excluded by ct angiography ( cta ) , infectious endocarditis and myocarditis were excluded clinically , biologically , echocardiographically . gated single - photon emission computerized tomography ( spect ) with technetium ( tc ) - 99 m evidenced hypokinesis of the inferior wall and of the interventricular septum , without perfusion defects or non - viable areas . with anticoagulant , anti - aggregant , calcium blocker , antiarrhythmic treatment during hospitalization , the patient continued to present frequent pain episodes of very high intensity , which were relieved by major analgesics or sometimes remitted spontaneously , accompanied by reversible ecg changes ( figures 2 and 3 ) . myocardial enzymes were reacted ( peak values : ck - mb = 318.9 ui / l ; ck = 2755 ui / l ; troponine i = 2.59 ng / ml ( normal range : 0.014 ng / ml ) , ast = 243 ui / l , alt = 47repeated transthoracic echocardiography ( tte ) was performed , which evidenced increased transprosthetic gradients consistent with severe aortic stenosis ( maxg = 7092.7 mmhg , meang = 3855.5 mmhg , vmax = 4.24.9 m / sec , aortic regurgitation ( ar ) grade ii due to intraprosthetic leak ) , moderate prosthesis - patient mismatch ( 0.670.8 cm2 / m2 ) , intermittent kinetic disorders in the inferior territory , and an echodense mass attached to the ventricular side of the prosthesis . subsequently , transesophageal echocardiography ( toe ) was performed , which allowed to visualize the interference of the mass with the closure of the prosthetic disc ( figure 4 ) . the patient was transferred to the service of cardiovascular surgery , where the stenosing subvalvular mass with a macroscopic pannus appearance , subsequently confirmed by microscopy ( figure 5 ) , was surgically removed in extracorporeal circulation . postoperative evolution ( at 2 months ) was favorable , without the recurrence of pain complaints and the restoration of effort tolerance . tte showed an improvement of transprosthetic gradients : maxg = 55 mmhg , meang = 28 mmhg , vmax = 3.7 m / sec , with the persistence of ar grade ii , hemodynamic insignificant . the discordance between repeated severe symptoms , ecg and enzymatic changes on the one hand , and the coronarographic and particularly , scintigraphic appearance on the other hand should be mentioned . normal coronarographic appearance does not exclude the presence of endothelial erosions visible by intracoronary imaging methods such as intravascular ultrasound ( ivus ) or optical coherence tomography ( oct ) , methods that were not applied in this case . coronary spasm can not be excluded , but there are several counter - arguments : it is frequently accompanied by st segment elevation , it was not evidenced during coronarography , a procedure performed during the crisis , no response to anticalcium drugs . what was intriguing and made the diagnosis of infarction difficult was the almost white scintigraphic result , suggesting that the event that induced the enzymatic increase left no visible traces on scintigraphy . transient kinetic disorders evidenced by some echocardiograms and by scintigraphy raised questions : interoperative variability or post - ischemic myocardial stunning . while excluding other possible cardiovascular diseases and taking into consideration prosthetic valve dysfunction , which was the only abnormality found , with the remission of symptoms post - intervention , final differential diagnosis was required between the various causes of increased transprosthetic gradients : stenosis due to pannus and / or thrombus , prosthesis - patient mismatch ( moderate , previously documented ) . differential diagnosis between thrombus and pannus is made based on clinical , echocardiographic and morphopathological criteria ( table i ) and is essential because therapeutic approaches are different . if in thrombotic obstruction , thrombolysis can be considered , this is contraindicated in the case of pannus , where the only valid therapeutic option is surgery ( valve replacement or pannus removal ) . in our case , pannus was supported by chronic evolution , effective anticoagulation , subvalvular location at the level of the aortic prosthesis , non - interference with the opening of the prosthetic disc . in contrast , the acute evolution of symptoms , with frequent episodes occurring during rest , under the conditions of transprosthetic gradients approximately similar to those determined 3 years before , was not characteristic of uncomplicated pannus . a possible thrombotic association , with repeated microembolizations , in the absence of imaging or morphopathological evidence , remained hypothetical . therapeutic approach in case of severe stenosis due to pannus involves surgical reintervention , consisting of valve replacement or pannus removal . valve replacement , a more complex procedure , is recommended only in certain conditions such as extensive circumferential pannus or a significantly altered prosthesis , based on the assumption of a marked inflammatory reaction in the case of replacement . in this case , an alternative could have been replacement with a larger size prosthesis , possibly with the previous enlargement of the aortic ring , and / or a newer generation prosthesis , with intrinsically reduced transprosthetic gradients . in conclusion , the presented case illustrates the problems that pannus - related prosthetic valve dysfunction , a late complication of mechanical prosthetic valve replacement , can pose in terms of clinical picture ( severity , discordant elements ) , differential diagnosis , as well as optimal therapeutic approach .
output:
