• 2718 Citations
  • 20 h-Index
1987 …2019
If you made any changes in Pure these will be visible here soon.

Research Output 1987 2019

  • 2718 Citations
  • 20 h-Index
  • 72 Article
  • 1 Chapter
  • 1 Comment/debate
  • 1 Review article
Filter
Article
2019
2 Citations (Scopus)
Open Access
Enalapril
Angiotensin-Converting Enzyme Inhibitors
Heart Failure
Pharmacokinetics
Safety
2018
1 Citation (Scopus)
Pediatrics
Transplants
Lung
Epoprostenol
Therapeutics
2016
21 Citations (Scopus)

Acute vasodilator response in pediatric pulmonary arterial hypertension current: Clinical practice from the TOPP registry

Douwes, J. M., Humpl, T., Bonnet, D., Beghetti, M., Ivy, D. D., Berger, R. M. F., Weintraub, R. G., Geiger, R., Marx, M., Jing, Z. C., Sondergaard, L., Apitz, C., Hager, A., Szatmári, A., Milanesi, O., Saji, T., Pulido, T., Moll, J., Michalak, K. W., Kawalec, W. & 14 others, Zuk, M., Fasnacht Boillat, M., Olguntürk, R., Kula, S., Alehan, D., Schulze-Neick, I., Atz, A. M., Mallory, G. B., Austin, E. D., Moore, D. J., Feinstein, J. A., Day, R. W., Yung, D. & Berger, J. T., márc. 22 2016, In : Journal of the American College of Cardiology. 67, 11, p. 1312-1323 12 p.

Research output: Article

Vasodilator Agents
Pulmonary Hypertension
Registries
Calcium Channel Blockers
Pediatrics
2 Citations (Scopus)

Evaluation of contraceptive methods in women with congenital heart disease in Germany, Hungary and Japan

Koerten, M. A., Szatmári, A., Niwa, K., Ruzsa, Z., Nagdyman, N., Niggemeyer, E., Peters, B., Schneider, K. T. M., Kuschel, B., Mizuno, Y., Berger, F., Bauer, U. M. M. & Kaemmerer, H., 2016, In : International Journal of Cardiology. 206, p. 13-18 6 p.

Research output: Article

Hungary
Contraception
Germany
Heart Diseases
Japan
26 Citations (Scopus)

Fluid Overload Is Associated With Higher Mortality and Morbidity in Pediatric Patients Undergoing Cardiac Surgery

Lex, D. J., Tóth, R., Czobor, N. R., Alexander, S. I., Breuer, T., Sápi, E., Szatmári, A., Székely, E., Gál, J. & Székely, A., febr. 24 2016, (Accepted/In press) In : Pediatric Critical Care Medicine.

Research output: Article

Thoracic Surgery
Pediatrics
Morbidity
Mortality
4 Citations (Scopus)

Frequency of miscarriage/stillbirth and terminations of pregnancy among women with congenital heart disease in Germany, Hungary and Japan

Koerten, M. A., Niwa, K., Szatmári, A., Hajnalka, B., Ruzsa, Z., Nagdyman, N., Niggemeyer, E., Peters, B., Schneider, K. T. M., Kuschel, B., Mizuno, Y., Berger, F., Kaemmerer, H. & Bauer, U. M. M., 2016, In : Circulation Journal. 80, 8, p. 1846-1851 6 p.

Research output: Article

Stillbirth
Hungary
Spontaneous Abortion
Germany
Heart Diseases
25 Citations (Scopus)

Haemodynamic characterisation and heart catheterisation complications in children with pulmonary hypertension: Insights from the Global TOPP Registry (tracking outcomes and practice in paediatric pulmonary hypertension)

Beghetti, M., Schulze-Neick, I., Berger, R. M. F., Ivy, D. D., Bonnet, D., Weintraub, R. G., Saji, T., Yung, D., Mallory, G. B., Geiger, R., Berger, J. T., Barst, R. J., Humpl, T., Mattos, S., Jing, Z. C., Han, Z. Y., Sondergaard, L., Jensen, T., Levy, M., Mebus, S. & 22 others, Apitz, C., Szatmári, A., Ablonczy, L., Milanesi, O., Favero, V., Pulido, T., De La Garza, P., Douwes, J. M., Brun, H., Moll, L., Michalak, K., Kawalec, W., Zuk, M., Fasnacht Boillat, M., Olgunturk, R., Serdar Kula, S., Alehan, D., Day, R. W., Austin, E., Moore, D. J., Atz, A. M. & Feinstein, J. A., jan. 15 2016, In : International Journal of Cardiology. 203, p. 325-330 6 p.

Research output: Article

Cardiac Catheterization
Pulmonary Hypertension
Registries
Vascular Resistance
Hemodynamics
2015
4 Citations (Scopus)

Left circumflex coronary artery occlusion due to a left atrial appendage closure device

Katona, A., Temesvári, A., Szatmári, A., Nemes, A., Forster, T. & Fontos, G., 2015, In : Postepy w Kardiologii Interwencyjnej. 11, 1, p. 69-70 2 p.

Research output: Article

Atrial Appendage
Coronary Occlusion
Coronary Vessels
Equipment and Supplies
Coronary Angiography
2014
54 Citations (Scopus)

A comparison of the systems for the identification of postoperative acute kidney injury in pediatric cardiac patients

Lex, D. J., Tóth, R., Cserép, Z., Alexander, S. I., Breuer, T., Sápi, E., Szatmári, A., Székely, E., Gál, J. & Székely, A., jan. 2014, In : Annals of Thoracic Surgery. 97, 1, p. 202-210 9 p.

Research output: Article

Acute Kidney Injury
Pediatrics
Kidney Diseases
Wounds and Injuries
Odds Ratio
1 Citation (Scopus)

Assessment of global tissue perfusion and oxygenation in neonates and infants after open-heart surgery

Gergely, M., Ablonczy, L., Székely, E. A., Sápi, E., Gál, J., Szatmári, A. & Székely, A., 2014, In : Interactive Cardiovascular and Thoracic Surgery. 18, 4, p. 426-431 6 p.

Research output: Article

Thoracic Surgery
Perfusion
Newborn Infant
Oxygen
Critical Care
1 Citation (Scopus)

Impact of the insulin and glucose content of the postoperative fluid on the outcome after pediatric cardiac surgery

Lex, D., Szántó, P., Breuer, T., Tóth, R., Gergely, M., Prodán, Z., Sápi, E., Szatmári, A., Szántó, T., Gál, J. & Székely, A., dec. 1 2014, In : Interventional Medicine and Applied Science. 6, 4, p. 160-169 10 p.

Research output: Article

Thoracic Surgery
Insulin
Pediatrics
Glucose
Length of Stay
56 Citations (Scopus)
Cardiac Care Facilities
Interprofessional Relations
Hospital Medical Staffs
Cardiac Surgical Procedures
Continuing Medical Education
1 Citation (Scopus)

Successful ablation of an incessant ventricular tachycardia in a 3.5 kg infant

Környei, L., Konta, L., Szatmári, A. & Rosenthal, E., febr. 2014, In : Europace. 16, 2, p. 283 1 p.

Research output: Article

Voltage-Sensitive Dye Imaging
Cardiac Electrophysiologic Techniques
Catheter Ablation
Ventricular Tachycardia
Electrocardiography
2013
14 Citations (Scopus)

Down syndrome and postoperative complications after paediatric cardiac surgery: A propensity-matched analysis

Tóth, R., Szántó, P., Prodán, Z., Lex, D. J., Sápi, E., Szatmári, A., Gál, J., Szántó, T. & Székely, A., okt. 2013, In : Interactive Cardiovascular and Thoracic Surgery. 17, 4, p. 691-697 7 p.

Research output: Article

Down Syndrome
Thoracic Surgery
Pediatrics
Length of Stay
Endocardial Cushion Defects
3 Citations (Scopus)
Atrial Heart Septal Defects
Brain Natriuretic Peptide
Heart Ventricles
Right Ventricular Function
Control Groups
1 Citation (Scopus)

Percutan bal pitvari fülcsezárás dabigatrannal való fülcsethrombus feloldását követoen

Kis, Z., Földesi, C., Pál, M., Som, Z., Csillik, A., Ábrahám, P., Temesvári, A., Fontos, G., Szatmári, A., Andréka, P. & Kardos, A., 2013, In : Orvosi Hetilap. 154, 7, p. 262-265 4 p.

Research output: Article

Atrial Appendage
Thrombosis
Atrial Fibrillation
Anticoagulants
Vitamin K
4 Citations (Scopus)

Postoperative differences between colonization and infection after pediatric cardiac surgery-a propensity matched analysis

Lex, D. J., Tóth, R., Cserép, Z., Breuer, T., Sápi, E., Szatmári, A., Gál, J. & Székely, A., júl. 2 2013, In : Journal of Cardiothoracic Surgery. 8, 1, 166.

Research output: Article

Thoracic Surgery
Pediatrics
Infection
Propensity Score
Postoperative Period
2012
62 Citations (Scopus)

Acute kidney injury is associated with higher morbidity and resource utilization in pediatric patients undergoing heart surgery

Tóth, R., Breuer, T., Cserép, Z., Lex, D., Fazekas, L., Sápi, E., Szatmári, A., Gál, J. & Székely, A., jún. 2012, In : Annals of Thoracic Surgery. 93, 6, p. 1984-1991 8 p.

Research output: Article

Acute Kidney Injury
Thoracic Surgery
Pediatrics
Morbidity
Propensity Score
1 Citation (Scopus)

A jobbkamra-kifolyási pálya rekonstrukciója elozoleg korrigált veleszületett szívhibák esetén fiatal-és felnottkorban

Hartyánszky, I., Székely, L., Szudi, L., Mihályi, S., Kádár, K., Temesvári, A., Bálint, H., Szatmári, A. & Tóth, A., aug. 1 2012, In : Orvosi Hetilap. 153, 31, p. 1219-1224 6 p.

Research output: Article

Congenital Heart Defects
Allografts
Right Ventricular Dysfunction
Pulmonary Valve
Ventricular Heart Septal Defects
213 Citations (Scopus)

A randomized, double-blind, placebo-controlled, dose-ranging study of oral sildenafil citrate in treatment-naive children with pulmonary arterial hypertension

Barst, R. J., Ivy, D. D., Gaitan, G., Szatmári, A., Rudzinski, A., Garcia, A. E., Sastry, B. K. S., Pulido, T., Layton, G. R., Serdarevic-Pehar, M. & Wessel, D. L., jan. 17 2012, In : Circulation. 125, 2, p. 324-334 11 p.

Research output: Article

Pulmonary Hypertension
Placebos
Hemodynamics
Therapeutics
Exercise
5 Citations (Scopus)
Thermodilution
Thoracic Surgery
Echocardiography
Hemodynamics
Newborn Infant
1 Citation (Scopus)

Ventricular septal rupture caused by myocardial bridge, solved by interventional closure device

Zóka, A., Andréka, P., Becker, D., Fontos, G., Merkely, B., Szabó, G., Szatmári, A. & Bárczi, G., 2012, In : Croatian Medical Journal. 53, 6, p. 627-630 4 p.

Research output: Article

Myocardial Bridging
Ventricular Septal Rupture
Coronary Disease
Echocardiography
Rupture
2011
3 Citations (Scopus)

Linee guida per il trattamento delle cardiopatie congenite dell'adulto (nuova versione 2010)

Baumgartner, H., Bonhoeffer, P., De Groot, N. M. S., De Haan, F., Deanfield, J. E., Galié, N., Gatzoulis, M. A., Gohlke-Baerwolf, C., Kaemmerer, H., Kilner, P., Meijboom, F., Mulder, B. J. M., Oechslin, E., Oliver, J. M., Serraf, A., Szatmári, A., Thaulow, E., Vouhe, P. R. & Walma, E., júl. 2011, In : Giornale Italiano di Cardiologia. 12, 7-8, p. 505-550 46 p.

Research output: Article

Cardiac Surgical Procedures
Congenital Heart Defects
Thromboembolism
Endocarditis
Pulmonary Hypertension
1 Citation (Scopus)

Sikeres szívátültetés veleszületett szívhiba korrekciós szívmutéte után. Sebésztechnikai problémák

Hartyánszky, I., Bodor, G., Mihályi, S., Székely, A., Kassai, I., Novák, E., Ablonczy, L., Szatmári, A. & Ofner, P., jan. 1 2011, In : Orvosi Hetilap. 152, 1, p. 23-26 4 p.

Research output: Article

Heart Transplantation
Heart Diseases
Tetralogy of Fallot
Hungary
4 Citations (Scopus)

Transpulmonary thermodilution in neonates undergoing arterial switch surgery

Székely, A., Breuer, T., Sápi, E., Székely, E., Szatmári, A., Tóth, M., Hauser, B. & Gál, J., febr. 2011, In : Pediatric Cardiology. 32, 2, p. 125-130 6 p.

Research output: Article

Thermodilution
Thorax
Extravascular Lung Water
Vascular Resistance
Stroke Volume
2010
1 Citation (Scopus)

A bal pitvari fülcse perkután zárása nonvalvularis pitvarfibrillációban-nemzetközi és hazai tapasztalatok

Fontos, G., Andréka, P., Temesvári, A., Wéber, D. & Szatmári, A., máj. 1 2010, In : Orvosi Hetilap. 151, 18, p. 725-734 10 p.

Research output: Article

Atrial Appendage
Anticoagulants
Atrial Fibrillation
Stroke
Hungary
1 Citation (Scopus)

Csecsemó- és Gyermekkori REDO mutéteket igénylo aortabillentyu-betegség. Az elso magyarországi Bentall-Konno-mutét gyermekkorban

Istvá, H., András, K., Imre, K., Edgár, S., László, A., Krisztina, K. & Szatmári, A., okt. 1 2010, In : Orvosi Hetilap. 151, 41, p. 1712-1715 4 p.

Research output: Article

Aortic Diseases
Aortic Valve Insufficiency
Aortic Valve
Hungary
Aortic Valve Stenosis
1371 Citations (Scopus)

ESC Guidelines for the management of grown-up congenital heart disease (new version 2010)

Baumgartner, H., Bonhoeffer, P., De Groot, N. M. S., De Haan, F., Deanfield, J. E., Galie, N., Gatzoulis, M. A., Gohlke-Baerwolf, C., Kaemmerer, H., Kilner, P., Meijboom, F., Mulder, B. J. M., Oechslin, E., Oliver, J. M., Serraf, A., Szatmári, A., Thaulow, E., Vouhe, P. R., Walma, E., Vahanian, A. & 45 others, Auricchio, A., Bax, J., Ceconi, C., Dean, V., Filippatos, G., Funck-Brentano, C., Hobbs, R., Kearney, P., McDonagh, T., Popescu, B. A., Reiner, Z., Sechtem, U., Sirnes, P. A., Tendera, M., Vardas, P., Widimsky, P., Swan, L., Andreotti, F., Beghetti, M., Borggrefe, M., Bozio, A., Brecker, S., Budts, W., Hess, J., Hirsch, R., Jondeau, G., Kokkonen, J., Kozelj, M., Kucukoglu, S., Laan, M., Lionis, C., Metreveli, I., Moons, P., Pieper, P. G., Pilossoff, V., Popelova, J., Price, S., Roos-Hesselink, J., Uva, M. S., Tornos, P., Trindade, P. T., Ukkonen, H., Walker, H., Webb, G. D. & Westby, J., dec. 2010, In : European Heart Journal. 31, 23, p. 2915-2957 43 p.

Research output: Article

Cardiovascular Pregnancy Complications
Thoracic Surgical Procedures
X Ray Computed Tomography
Congenital Heart Defects
Magnetic Resonance Angiography
1 Citation (Scopus)

Impact of blood glucose values in patients with and without insulin treatment following paediatric cardiac surgery

Breuer, T., Sápi, E., Hartyánszky, I. L., Cserép, Z., Vargha, P., Treszl, A., Kertai, M., Gál, J., Tóth, M., Szatmári, A. & Székely, A., márc. 1 2010, In : Interventional Medicine and Applied Science. 2, 1, p. 10-16 7 p.

Research output: Article

Thoracic Surgery
Blood Glucose
Insulin
Pediatrics
Therapeutics
1 Citation (Scopus)

Recommendations from the Association for European Paediatric Cardiology for training in diagnostic and interventional cardiac catheterisation

Witsenburg, M., Qureshi, S., Carminati, M., Gewillig, M., Brzezinska-Rajszys, G. & Szatmári, A., aug. 2010, In : Cardiology in the Young. 20, 4, p. 470-472 3 p.

Research output: Article

Cardiac Catheterization
2009

Meningealis izgalmi tünetekkel jelentkezo infektív endocarditis

Aschenbrenner, Z., Simon, G., Mayer, G., Szokó, M., Hartyánszky, I., Szatmári, A. & Simon, G., okt. 1 2009, In : Orvosi Hetilap. 150, 41, p. 1909-1911 3 p.

Research output: Article

Endocarditis
Mitral Valve
Systolic Murmurs
Heart Murmurs
Spinal Puncture
102 Citations (Scopus)

Risks and Predictors of Blood Transfusion in Pediatric Patients Undergoing Open Heart Operations

Székely, A., Cserép, Z., Sápi, E., Breuer, T., Nagy, C. A., Vargha, P., Hartyánszky, I., Szatmári, A. & Treszl, A., jan. 2009, In : Annals of Thoracic Surgery. 87, 1, p. 187-197 11 p.

Research output: Article

Blood Transfusion
Pediatrics
Propensity Score
Infection
Odds Ratio
4 Citations (Scopus)

Tapasztalataink a fiatal- és felno′ttkori veleszületett szívhibák sebészi kezelésében 2001-2008

Hartyánszky, I., Székely, A., Király, L., Prodán, Z., Mihályi, S., Bodor, G., Tamás, C., Kassai, I., Fazakas, L., Temesvári, A. & Szatmári, A., szept. 1 2009, In : Orvosi Hetilap. 150, 37, p. 1739-1743 5 p.

Research output: Article

Congenital Heart Defects
Heart Ventricles
Pulmonary Hypertension
Aneurysm
Allografts
2008
32 Citations (Scopus)

Aprotinin and renal dysfunction after pediatric cardiac surgery

Székely, A., SÁpi, E., Breuer, T., Kertai, M., Bodor, G., Vargha, P. & Szatmári, A., febr. 2008, In : Paediatric Anaesthesia. 18, 2, p. 151-159 9 p.

Research output: Article

Aprotinin
Thoracic Surgery
Pediatrics
Kidney
Dialysis
1 Citation (Scopus)

A szívtranszplantáció helye a gyermekszívsebészetben. Az elso sikeres gyermekszív-átültetés Magyarországon

Hartyánszky, I., Ablonczy, L., Bodor, E., Hartyánszky, I., Bodor, G., Mihályi, S., Sápi, E., Héthársi, B. & Szatmári, A., jún. 1 2008, In : Orvosi Hetilap. 149, 22, p. 1035-1037 3 p.

Research output: Article

Hungary
Heart Transplantation
Thoracic Surgery
Pediatrics
Mycophenolic Acid
1 Citation (Scopus)

Veleszületett szïvbetegséghez társuló ritmuszavarok katéterablatiós kezelése

Szili-Török, T., Szeghy, S., Kardos, A., Környei, L., Paprika, D., Szatmári, A. & Temesvári, A., jan. 20 2008, In : Orvosi Hetilap. 149, 3, p. 115-119 5 p.

Research output: Article

Cardiac Arrhythmias
Heart Diseases
Therapeutics
Recurrence
Catheter Ablation
2007
23 Citations (Scopus)

Evolution of left ventricular function in paediatric patients with permanent right ventricular pacing for isolated congenital heart block: A medium term follow-up

Vatasescu, R., Shalganov, T., Paprika, D., Kornyei, L., Prodan, Z., Bodor, G., Szatmári, A. & Szili-Torok, T., ápr. 15 2007, In : Europace. 9, 4, p. 228-232 5 p.

Research output: Article

Left Ventricular Function
Pediatrics
Heart Rate
Congenital heart block
Incidence
10 Citations (Scopus)
Left Ventricular Function
Heart Diseases
Pediatrics
Congenital Heart Defects
Electrocardiography
7 Citations (Scopus)

N-terminal probrain natriuretic peptide level inversely correlates with cardiac index after arterial switch operation in neonates

Breuer, T., Sápi, E., Skoumal, R., Tóth, M., Ala-Kopsala, M., Vuolteenaho, O., Leppäluoto, J., Ruskoaho, H., Szatmári, A. & Székely, A., aug. 2007, In : Paediatric Anaesthesia. 17, 8, p. 782-788 7 p.

Research output: Article

Natriuretic Peptides
Newborn Infant
Hemodynamics
Creatinine
Thermodilution
18 Citations (Scopus)

Recommendations on sub-speciality accreditation in cardiology: The Coordination Task Force on Sub-speciality Accreditation of the European Board for the Speciality of Cardiology

Lopez-Sendon, J., Mills, P., Weber, H., Michels, R., Mario, C. D., Filippatos, G. S., Heras, M., Fox, K., Merino, J., Pennell, D. J., Sochor, H., Ortoli, J., Szatmári, A., Pinto, F., Polak, P., Amlie, J. P., Oto, A., Lainscak, M., Fox, K., Kearney, P. & 3 others, Gonçalves, L., Huikuri, H. & Carrera, C., szept. 2007, In : European Heart Journal. 28, 17, p. 2163-2171 9 p.

Research output: Article

Specialty Boards
Graduate Medical Education
Clinical Competence
Accreditation
Advisory Committees
2006
72 Citations (Scopus)

Intraoperative and postoperative risk factors for prolonged mechanical ventilation after pediatric cardiac surgery

Székely, A., Sápi, E., Király, L., Szatmári, A. & Dinya, E., nov. 2006, In : Paediatric Anaesthesia. 16, 11, p. 1166-1175 10 p.

Research output: Article

Artificial Respiration
Thoracic Surgery
Tracheobronchomalacia
Pediatrics
Cardiopulmonary Bypass
3 Citations (Scopus)

Képes-e a jobb kamra hosszú távon biztosítani a szisztémás keringést? Nagyér-transzpozíciós betegeken végzett Senning-mutétek késoi eredményei

Hartyánszky, I., Kádár, K., Oprea, V., Lozsádi, K., Szabolcs, J. & Szatmári, A., nov. 12 2006, In : Orvosi Hetilap. 147, 45, p. 2155-2160 6 p.

Research output: Article

Transposition of Great Vessels
Heart Ventricles
Echocardiography
Electrocardiography
Right Ventricular Function
1 Citation (Scopus)

Nyitott foramen ovale katéteres zárása, a cryptogen agyi történés szekunder prevenciója

Temesvári, A., Bálint, O. H., Liptai, C., Kancz, S., Németh, B. & Szatmári, A., okt. 22 2006, In : Orvosi Hetilap. 147, 42, p. 2035-2039 5 p.

Research output: Article

Patent Foramen Ovale
Stroke
Embolism
Atrial Septum
Hungary
Hungary
Pediatrics
Mortality
Observation
Newborn Infant
2 Citations (Scopus)
Diagnostic Services
Cardiology
Echocardiography
Magnetic Resonance Spectroscopy
Diagnostic Imaging
37 Citations (Scopus)
Diagnostic Services
Cardiology
Echocardiography
Magnetic Resonance Spectroscopy
Diagnostic Imaging
7 Citations (Scopus)
Diagnostic Services
Cardiology
Echocardiography
Magnetic Resonance Spectroscopy
Diagnostic Imaging
2005

Az intracardialis ultrahangvizsgálat használata a szív elektrofiziológiában: Áttekintés az elso hazai vizsgálatok kapcsán

Szili-Török, T., Osztheimer, I., Paprika, D., Temesvári, A., Környei, L., Ofner, P. & Szatmári, A., 2005, In : Orvosi Hetilap. 146, 21, p. 1165-1170 6 p.

Research output: Article

Cardiac Electrophysiology
Echocardiography
Cardiac Arrhythmias
Catheter Ablation
Electrophysiology
1 Citation (Scopus)

Felnottkori congenitalis szívsebészet gyermekkardioló giai és szívsebészeti központban

Király, L., Temesvári, A., Székely, A., Prodán, Z., Liptai, C., Szudi, L., Hartyánszky, I., Havrancsik, C. & Szatmári, A., 2005, In : Orvosi Hetilap. 146, 5, p. 209-214 6 p.

Research output: Article

Tertiary Healthcare
Pediatrics
Reoperation
Reconstructive Surgical Procedures
Low Cardiac Output
7 Citations (Scopus)

Hypoplastic aortic arch in newborns rapidly adapts to post-coarctectomy circulatory conditions

Kiraly, L., Környei, L., Mogyorossy, G. & Szatmári, A., febr. 2005, In : Heart. 91, 2, p. 233-234 2 p.

Research output: Article

Blood Vessel Prosthesis Implantation
Aortic Coarctation
Blood Flow Velocity
Doppler Echocardiography
Left Ventricular Dysfunction