Subscribe to RSS
DOI: 10.1055/s-0032-1326724
Cardiac Surgery in Germany during 2011: A Report on Behalf of the German Society for Thoracic and Cardiovascular Surgery
Abstract
All cardiac surgical procedures performed in 78 German cardiac surgical units throughout the year 2011 are presented in this report, based on a voluntary registry which is organized by the German Society for Thoracic and Cardiovascular Surgery. In 2011, a total of 100,291 cardiac surgical procedures (implantable cardioverter defibrillator and pacemakers procedures excluded) have been collected in this registry. More than 13.4% of the patients were older than 80 years compared with 12.4% in 2010. Hospital mortality in 41,976 isolated coronary artery bypass graft procedures (14.7% off-pump) was 2.9%. In 26,972 isolated valve procedures (including 5,210 catheter-based procedures), an in-hospital mortality of 5.2% has been observed.
This voluntary registry of the German Society for Thoracic and Cardiovascular Surgery will continue to be an important tool enabling quality control and illustrating current facts and the development of cardiac surgery in Germany.
#
Keywords
cardiac surgery - registry - heart valve diseases - coronary heart disease - congenital heart disease - vascular surgery - organ transplantation - heart rhythm disordersIntroduction
Increasing demands for quality control in medicine—by patients, relatives, insurance companies, and authorities all over the world—have stimulated the development of a wide range of registries and other tools to answer those needs. As early as in 1978, the German Society for Thoracic and Cardiovascular Surgery (www.dgthg.de) decided to set up a voluntary registry for cardiac surgical procedures. The aim of this registry continues to illustrate the development of cardiac surgery in Germany and to allow each individual cardiac surgical unit to compare its own results to the nationwide results.
Innovative technologies as minimal invasive mitral valve surgery, off-pump surgery, and still experimental procedures such as transcatheter (transapical or transvascular) aortic valve implantation (TAVI) ([Table V1]) have been included in the registry to monitor the development in this field, important for the future of patient care.
The registry data are published once a year since 1989.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] The following report contains the assorted data for the year 2011.
#
Materials and Methods
Since 2004, the standardized questionnaire asks for detailed information about each individual procedure exactly defined by one or more operation codes (German Operationen- und Prozedurenschlüssel [OPS]).
All centers had to complete the questionnaire until January 20, 2012, asking for all performed procedures and associated hospital mortality in each institution. The completed questionnaires were sent to the office of the German Society for Thoracic and Cardiovascular Surgery in Berlin, and were evaluated for completeness and compiled for further analysis, thus ensuring anonymity for the individual center. The compilation algorithm guaranties a high compliance for submission of the complete dataset.
Inclusion criteria for the registry 2011 were all individual surgical procedures performed between January 1, 2011 and December 31, 2011, unrelated to admission or discharge dates as compared with other registries.
Alike to all previous reports, the number of procedures was counted, not individual patients, for example, a patient requiring additional coronary surgery due to a complication after aortic valve replacement during the same admission would be counted in the category “aortic valve replacement” and in the category “coronary surgery.” Thus the registry contains more procedures than the actual number of patients operated on.
Mortality was defined as in-hospital mortality. As per the definition, the observed mortality was attributed to the first heart surgical procedure, for example, the death of a patient requiring additional coronary artery bypass grafting (CABG) due to a complication after aortic valve replacement during the same admission would be attributed only to the aortic valve but not to the coronary surgery group.
The main reason for this structural setup of the registry, like in previous years, was getting detailed information on all performed procedures and not only counting the number of the treated patients. Another reason was to simplify the process of data acquisition thus enabling all cardiac surgery units in Germany, the submission of a complete dataset, regardless of their existing hardware and software.
In 2011, a total of 79 units performed heart surgery, 78 units answered the questionnaire and delivered a complete dataset for the year 2011 including hospital mortality rates. Due to technical reasons, one unit with ~200 cases could not deliver the data.
#
Registry Data 2011
[Table 1] demonstrates the development of procedures using cardiopulmonary bypass (CPB) over the past 30 years in Germany. The number of heart operations procedures with CPB remains on a stable level.
Overall, 173,347 procedures were reported to the registry for the year 2011, an increase of 4.0% (2010: 166,621 procedures). A total of 100,291 cardiac surgical procedures (excluded: implantable cardioverter defibrillator (ICD), pacemakers, and miscellaneous procedures without CPB) display an increase of 1.74% (n = 1,714) compared with the year of 2010 (98,755 procedures) ([Table 2]). The following tables and figures ([Tables 3] to [6], [Tables V1] to [V7], [Tables C1] to [C3], [Tables Con1] and [Con2], [Tables Mis1] to [Mis5] and [Figs. 1] to [11]) represent the compiled registry data for 2011 classified in individual categories.
ICD, implantable cardioverter defibrillator; CPB, cardiopulmonary bypass.
Note: The % indicates changes compared with 2010.
Number of Operations |
< 500 |
500–999[a] |
1000–1499 |
1500–1999 |
2000–5000 |
Number of Units |
5 |
25 |
26 |
13 |
9 |
Average Per Unit |
396 |
777 |
1194 |
1742 |
2802 |
Minimum–Maximum |
245–477 |
510–974 |
1002–1458 |
1516–1968 |
2075–3823 |
CPB, cardiopulmonary bypass.
a One unit is performing pediatric cardiac surgery only.
Type of Surgery Performed |
Number of Units |
---|---|
Coronary Surgery |
77 |
Valve Surgery |
77 |
Surgery of Congenital Heart Diseases With CPB in Children < 1 Year |
26[a] |
Heart Transplantation |
22[b] |
Heart–Lung Transplantation |
5 |
CPB, cardiopulmonary bypass.
a Surgery for congenital heart disease with CPB in children < 1 year (n 2037); thereof: 2 to 18 operations in five units, 26–45 operations in five units, 52–84 operations in eight units, and 109–250 operations in eight units.
b Heart transplantations (n = 355): 70% of the total annual heart transplantations are performed by 8 of 22 units with ≥ 15 heart transplantation per year; thereof: 1–4 transplants in three units, 5–9 transplants in six units, 10–19 transplants in seven units, and 21–77 transplants in six units.
Demographic Data |
2011 |
2010 |
||
---|---|---|---|---|
Emergency Operations |
11911 |
11.9% |
11850 |
12.0% |
Redo Procedures |
8511 |
8.5% |
8458 |
8.6% |
Age > 69 Years[a] |
95456 |
53.6% |
93646 |
52.2% |
CPB, cardiopulmonary bypass.
Note: The numbers in each category reflect procedures and not individual patients.
a Without patients younger than 20 years.
ICD, implantable cardioverter defibrillator.
Note: All coronary surgery (48743 on-pump and 6556 off-pump procedures) and all congenital surgery procedures are included in this table.
part., partial; mic, minimally invasive surgery.
Note: A total of 2280 (41%) mitral valve procedures were done using a minimally invasive access. The number of isolated conventional aortic valve replacement showed no difference from 2010 to 2011 (2010: 11689 and 2011:11668 procedures).
Type of Valve |
n |
Deaths |
% |
---|---|---|---|
Prosthesis |
1689 |
41 |
2.4 |
Xenograft |
9846 |
334 |
3.4 |
Homograft |
37 |
2 |
5.4 |
Reconstruction |
96 |
3 |
3.1 |
Total |
11668 |
380 |
3.3 |
transcatheter aortic valve implantation.
Note: Out of 11668 procedures, 1794 (15%) were done by a partial sternotomy access. TAVI excluded.
Note: Combined procedures (coronary artery bypass graft and aortic surgery) are not included.
Type of Valve |
n |
Deaths |
% |
---|---|---|---|
Prosthesis |
579 |
28 |
4.8 |
Xenograft |
1334 |
152 |
11.4 |
Homograft |
11 |
3 |
27.3 |
Reconstruction |
3587 |
66 |
1.8 |
Total |
5511 |
249 |
4.5 |
Note: Out of 5511 procedures, 2280 (41%) were done using a minimally invasive access. Transcatheter procedures excluded.
Combination |
n |
Deaths |
% |
---|---|---|---|
Aortic + Mitral |
1854 |
153 |
8.3 |
Mitral + Tricuspid |
1419 |
110 |
7.8 |
Aortic + Tricuspid |
188 |
33 |
17.6 |
Tricuspid + Pulmonary |
17 |
2 |
11.8 |
Aortic + Pulmonary[a] |
122 |
1 |
0.8 |
Aortic + Mitral + Tricuspid |
357 |
50 |
14.0 |
Aortic + Mitral + Pulmonary |
5 |
3 |
60.0 |
Total |
3962 |
352 |
8.9 |
Note: Transcatheter procedures are not included.
a Including Ross procedures.
Mitral Valve Surgery |
Replacement |
Reconstruction |
||||||||
---|---|---|---|---|---|---|---|---|---|---|
n |
Total Deaths |
% Death |
% Reconstruction |
n |
Deaths |
% Death |
n |
Deaths |
% Death |
|
Isolated |
5511 |
249 |
4.5 |
65.1 |
1924 |
183 |
9.5 |
3587 |
66 |
1.8 |
Mitral Valve + |
||||||||||
Aortic Valve |
1854 |
153 |
8.3 |
62.8 |
689 |
103 |
14.9 |
1165 |
50 |
4.3 |
Tricuspid Valve Reconstruction[a] |
1390 |
104 |
7.5 |
64.3 |
496 |
55 |
11.1 |
894 |
49 |
5.5 |
CABG |
2590 |
269 |
10.4 |
68.6 |
812 |
139 |
17.1 |
1778 |
130 |
7.3 |
CABG + Aortic Valve Replacement |
957 |
114 |
11.9 |
70.7 |
280 |
52 |
18.6 |
677 |
62 |
9.2 |
Total |
12302 |
889 |
7.2 |
65.9 |
4201 |
532 |
12.7 |
8101 |
357 |
4.4 |
CABG, coronary artery bypass graft.
a Twenty-nine procedures (not specified Mitral valve + tricuspid valve surgery) excluded. Deaths %: 20.7 (6/29).
With CPB |
Without CPB |
||||||
---|---|---|---|---|---|---|---|
Total |
Deaths |
Death % |
n |
Deaths |
n |
Deaths |
|
Aortic Valve Implantation |
5083 |
358 |
7.0 |
121 |
42 |
4962 |
316 |
Transvascular Access[a] |
2306 |
117 |
5.1 |
34 |
13 |
2272 |
104 |
Transapical Access |
2777 |
241 |
8.7 |
87 |
29 |
2690 |
212 |
Mitral Valve |
120 |
5 |
4.2 |
2 |
0 |
118 |
5 |
Repair |
94 |
1 |
1.1 |
1 |
0 |
93 |
1 |
Implantation[b] |
26 |
4 |
15.4 |
1 |
0 |
25 |
4 |
Aortic Valve Implantation[b] + CABG |
38 |
8 |
21.1 |
15 |
5 |
23 |
3 |
Total |
10444 |
734 |
7.0 |
261 |
89 |
10183 |
645 |
TAVI, transcatheter aortic valve implantation; CPB, cardiopulmonary bypass; CABG, coronary artery bypass graft.
Note: Pulmonary valve implantation for the correction of congenital lesions are not included, one procedure was reported for adults without congenital lesion. With the use of CPB, 2.3% of TAVI procedures were performed. It has to be assumed that CPB was mostly used in emergency situations, which explains the lethality of 34.7% in this group. Nevertheless, this underlines the necessity of a fully equipped surrounding for TAVI procedures where CPB is on standby for urgent use.
a Femoral, subclavian or transaortic access.
b Endovascular and transapical access.
CABG, coronary artery bypass graft; CPB, cardiopulmonary bypass.
Number of Grafts |
n |
Deaths |
% |
---|---|---|---|
Single |
1126 |
66 |
5.9 |
Double |
7748 |
226 |
2.9 |
Triple |
15749 |
489 |
3.1 |
Quadruple |
8767 |
236 |
2.7 |
Quintuple + more |
2431 |
71 |
2.9 |
Total |
35821 |
1088 |
3.0 |
CABG, coronary artery bypass graft; CPB, cardiopulmonary bypass.
Number of Grafts |
n |
Deaths |
% |
---|---|---|---|
Single |
1514 |
34 |
2.2 |
Double |
1807 |
53 |
2.9 |
Triple |
2004 |
33 |
1.6 |
Quadruple |
708 |
8 |
1.1 |
Quintuple + More |
122 |
1 |
0.8 |
Total |
6155 |
129 |
2.1 |
CABG, coronary artery bypass graft.
CPB, cardiopulmonary bypass.
ASD, atrial septal defect; AV, atrioventricular; VSD, ventricular septal defect; DORV, double outlet right ventricle; TGA, transposition at the great arteries; PDA, patent ductus arteriosus.
Note: Eurotransplant (ET) has reported for the same period 341 heart transplantations (HTx), 13 heart + kidney transplantations, 2 heart + liver transplantations, 10 heart–lung transplantations, 268 double lung, 57 single lung transplantations (LuTx), 1 lung + kidney transplantations, and 1 lung + liver transplantations. The differences (ET: −28 LuTx, −1 HTx) may be explained by different inclusion criteria (time of transplantation) for the registry and the ET database.
CPB, cardiopulmonary bypass.
Aortic Surgery[a] |
With CPB |
Without CPB |
||||
---|---|---|---|---|---|---|
n |
Deaths |
% |
n |
Deaths |
% |
|
Supracoronary Ascending |
1523 |
88 |
5.8 |
|||
Infracoronary Ascending |
– |
|||||
Mechanical Valve Conduits |
623 |
40 |
6.4 |
|||
Biological Valve Conduits |
681 |
76 |
11.2 |
|||
David |
477 |
7 |
1.5 |
|||
Yacoub |
130 |
4 |
3.1 |
|||
Other |
277 |
21 |
7.6 |
|||
Supracoronary Ascending + Aortic Valve Replacement |
1331 |
56 |
4.2 |
|||
Aortic Arch Replacement[b] |
1419 |
165 |
11.6 |
|||
Descending |
105 |
13 |
12.4 |
16 |
4 |
25.0 |
Thoracoabdominal |
78 |
23 |
29.5 |
31 |
6 |
19.4 |
Endostent Descending |
14 |
0 |
0.0 |
496 |
27 |
5.4 |
Total |
6658 |
493 |
7.4 |
543 |
37 |
6.8 |
Note: All procedures involving aortic surgery are included in this table. Isolated aortic surgery as well as all possible combined procedures (e.g., additional CABG) are summarized in this category.
a Abdominal aortic surgery is not included: 580 abdominal and 467 endostent abdominal.
b All possible combined procedures are included in this category; the only common denominator is aortic arch surgery.
CPB, cardiopulmonary bypass; CABG, coronary artery bypass graft.
ICD, implantable cardioverter defibrillator; CPB, cardiopulmonary bypass.
Note: Included in this table are all isolated ablation procedures and all possible combination procedures (e.g., CABG + ablation). Total of n = 343 procedures are not specified with regard to endocardiac/epicardiac ablation.
CABG, coronary artery bypass graft.
As in previous years, several important developments continued also in 2011. Over the past 18 years, the age distribution ([Fig. 6]) demonstrates a shift to the categories with older patients. Currently, 53.6% of the cardiac procedures are performed in patients 70 years or older and 13.4% in patients 80 years or older. However, mortality remains the same or even decreased slightly over the past 18 years (see [Fig. 2]). Although the number of CABG decreased while the number of off-pump procedures for coronary heart disease increased to 14.7% (2010: 14.2%) ([Fig. 3]).
Since 2004 more than 50% of isolated mitral valve procedures are reconstructions, in 2011 more than 65% of the patients with mitral valve disease received a mitral valve reconstruction ([Fig. 8]). For correct interpretation of [Fig. 8], it is important to assert that, due to the data collection method (German OPS), all patients with various mitral valve diseases such as mitral valve stenosis, valve calcification, endocarditis, and patients under emergent conditions are included. The operation codes by itself give no information about the underlying disease. The reconstruction rate would certainly be higher if only patients would be included where a reconstruction is feasible. In other publications, for example, Gammie et al,[22] the reconstruction rate must be interpreted very carefully compared with our registry data because in their publication, patients with mitral valve stenosis, endocarditis, and in emergent conditions are excluded.
The increase of left ventricular assist device implantation ([Fig. 10]) emphasizes the increasing relevance of mechanical circulatory support.
The most remarkable evolution is the extensive increase of TAVI over the past 6 years ([Fig. 5]), while the number of isolated aortic valve replacements by open surgery remains stable. Starting in 2006 with 78 procedures (0.67% of isolated aortic valve procedures), 5,083 TAVI are reported in 2011 (30.5%). However, it should be kept in mind that the 78 units which contribute at this registry are not the only sites which are performing TAVI in Germany. TAVI via transvascular access are also performed in cardiology units without availability of a heart surgical unit. With the use of CPB, 2.3% of TAVI procedures were performed. It has to be assumed that CPB was mostly used in emergency situations, which explains the lethality of 34.7% in this group. Nevertheless, this underlines the necessity of a fully equipped surrounding for TAVI procedures where CPB is on standby for urgent use.
In the context of TAVI, two other quality assurance initiatives in Germany will be of great interest: the German Aortic Valve Registry and the legal quality assurance (§137 SGB V), which the AQUA-Institute is responsible for.
#
Discussion
This report enables a comprehensive overview of all cardiac surgical procedures performed in Germany in 2011. The accuracy of this registry is reliable due to the implemented compilation algorithm using operation codes. This assumption is supported by other authors who could demonstrate a high accuracy for major outcome parameters in unaudited registries.[23] Alike to previous reports, we can conclude that cardiac surgery is performed on a high level with a low in-hospital mortality compared with other international registries. This conclusion is important especially in the era of continuously increasing patient age combined with relevant comorbidities, both leading to a higher perioperative risk profile.
Compared with 2010, the number of cardiac surgical procedures has stabilized due to the high volume of TAVI.
Further improvements for the structure of the registry are necessary to allow a more detailed and risk adjusted analysis of the collected data. However, significant structural changes of the registry have to ensure data compatibility to allow further longitudinal data analysis.
The future of this voluntary registry as well as its further development will depend on continuous efforts of each individual cardiac surgical unit. This will be of outstanding importance to guarantee the ongoing high quality of cardiac surgery in Germany.
#
#
Acknowledgments
On behalf of the German Society for Thoracic and Cardiovascular Surgery, the authors would like to thank the chairmen and their coworkers of all heart surgery units in Germany for their continuous cooperation and support for realizing this registry report.
-
References
- 1 Kalmar P, Irrgang E. Cardiac surgery in the Federal Republic of Germany during 1989. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1990; 38 (3) 198-200
- 2 Kalmar P, Irrgang E. Cardiac surgery in the Federal Republic of Germany during 1990. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1991; 39 (3) 167-169
- 3 Kalmar P, Irrgang E. Cardiac surgery in Germany during 1991. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1992; 40 (3) 163-165
- 4 Kalmar P, Irrgang E. Cardiac surgery in Germany during 1992. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1993; 41 (3) 202-204
- 5 Kalmar P, Irrgang E. Cardiac surgery in Germany during 1993. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1994; 42 (3) 194-196
- 6 Kalmar P, Irrgang E. Cardiac surgery in Germany during 1994. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1995; 43 (3) 181-183
- 7 Kalmár P, Irrgang E. Cardiac surgery in Germany during 1995. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1996; 44 (3) 161-164
- 8 Kalmár P, Irrgang E. Cardiac surgery in Germany during 1996. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1997; 45 (3) 134-137
- 9 Kalmár P, Irrgang E. Cardiac surgery in Germany during 1997. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1998; 46 (5) 307-310
- 10 Kalmàr P, Irrgang E. Cardiac surgery in Germany during 1998. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1999; 47 (4) 260-263
- 11 Kalmár P, Irrgang E. Cardiac surgery in Germany during 1999. Thorac Cardiovasc Surg 2000; 48 (4) XXVII-XXX
- 12 Kalmár P, Irrgang E. Cardiac surgery in Germany during 2001: a report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2002; 50 (6) 30-35
- 13 Kalmár P, Irrgang E ; German Society for Thoracic and Cardiovascular Surgery. Cardiac surgery in Germany during 2002: a report by German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2003; 51 (5) 25-29
- 14 Kalmár P, Irrgang E ; German Society for Thoracic and Cardiovascular Surgery. Cardiac surgery in Germany during 2003: a report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2004; 52 (5) 312-317
- 15 Gummert JF, Funkat A, Krian A. Cardiac surgery in Germany during 2004: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2005; 53 (6) 391-399
- 16 Gummert JF, Funkat A, Beckmann A, Hekmat K, Ernst M, Krian A. Cardiac surgery in Germany during 2005: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2006; 54 (5) 362-371
- 17 Gummert JF, Funkat A, Beckmann A , et al. Cardiac surgery in Germany during 2006: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2007; 55 (6) 343-350
- 18 Gummert JF, Funkat A, Beckmann A , et al; German Society for Thoracic and Cardiovascular Surgery. Cardiac surgery in Germany during 2007: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2008; 56 (6) 328-336
- 19 Gummert JF, Funkat A, Beckmann A , et al. Cardiac surgery in Germany during 2008. A report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2009; 57 (6) 315-323
- 20 Gummert JF, Funkat A, Beckmann A , et al. Cardiac surgery in Germany during 2009. A report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2010; 58 (7) 379-386
- 21 Gummert JF, Funkat AK, Beckmann A , et al. Cardiac surgery in Germany during 2010: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2011; 59 (5) 259-267
- 22 Gammie JS, Zhao Y, Peterson ED, O'Brien SM, Rankin JS, Griffith BP. J. Maxwell Chamberlain Memorial Paper for adult cardiac surgery. Less-invasive mitral valve operations: trends and outcomes from the Society of Thoracic Surgeons Adult Cardiac Surgery Database. Ann Thorac Surg 2010; 90 (5) 1401-1408 , 1410, e1, discussion 1408–1410
- 23 Herbert MA, Prince SL, Williams JL, Magee MJ, Mack MJ. Are unaudited records from an outcomes registry database accurate?. Ann Thorac Surg 2004; 77 (6) 1960-1964 , discussion 1964–1965
Address for correspondence and reprint requests
-
References
- 1 Kalmar P, Irrgang E. Cardiac surgery in the Federal Republic of Germany during 1989. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1990; 38 (3) 198-200
- 2 Kalmar P, Irrgang E. Cardiac surgery in the Federal Republic of Germany during 1990. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1991; 39 (3) 167-169
- 3 Kalmar P, Irrgang E. Cardiac surgery in Germany during 1991. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1992; 40 (3) 163-165
- 4 Kalmar P, Irrgang E. Cardiac surgery in Germany during 1992. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1993; 41 (3) 202-204
- 5 Kalmar P, Irrgang E. Cardiac surgery in Germany during 1993. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1994; 42 (3) 194-196
- 6 Kalmar P, Irrgang E. Cardiac surgery in Germany during 1994. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1995; 43 (3) 181-183
- 7 Kalmár P, Irrgang E. Cardiac surgery in Germany during 1995. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1996; 44 (3) 161-164
- 8 Kalmár P, Irrgang E. Cardiac surgery in Germany during 1996. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1997; 45 (3) 134-137
- 9 Kalmár P, Irrgang E. Cardiac surgery in Germany during 1997. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1998; 46 (5) 307-310
- 10 Kalmàr P, Irrgang E. Cardiac surgery in Germany during 1998. A report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 1999; 47 (4) 260-263
- 11 Kalmár P, Irrgang E. Cardiac surgery in Germany during 1999. Thorac Cardiovasc Surg 2000; 48 (4) XXVII-XXX
- 12 Kalmár P, Irrgang E. Cardiac surgery in Germany during 2001: a report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2002; 50 (6) 30-35
- 13 Kalmár P, Irrgang E ; German Society for Thoracic and Cardiovascular Surgery. Cardiac surgery in Germany during 2002: a report by German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2003; 51 (5) 25-29
- 14 Kalmár P, Irrgang E ; German Society for Thoracic and Cardiovascular Surgery. Cardiac surgery in Germany during 2003: a report by the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2004; 52 (5) 312-317
- 15 Gummert JF, Funkat A, Krian A. Cardiac surgery in Germany during 2004: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2005; 53 (6) 391-399
- 16 Gummert JF, Funkat A, Beckmann A, Hekmat K, Ernst M, Krian A. Cardiac surgery in Germany during 2005: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2006; 54 (5) 362-371
- 17 Gummert JF, Funkat A, Beckmann A , et al. Cardiac surgery in Germany during 2006: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2007; 55 (6) 343-350
- 18 Gummert JF, Funkat A, Beckmann A , et al; German Society for Thoracic and Cardiovascular Surgery. Cardiac surgery in Germany during 2007: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2008; 56 (6) 328-336
- 19 Gummert JF, Funkat A, Beckmann A , et al. Cardiac surgery in Germany during 2008. A report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2009; 57 (6) 315-323
- 20 Gummert JF, Funkat A, Beckmann A , et al. Cardiac surgery in Germany during 2009. A report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2010; 58 (7) 379-386
- 21 Gummert JF, Funkat AK, Beckmann A , et al. Cardiac surgery in Germany during 2010: a report on behalf of the German Society for Thoracic and Cardiovascular Surgery. Thorac Cardiovasc Surg 2011; 59 (5) 259-267
- 22 Gammie JS, Zhao Y, Peterson ED, O'Brien SM, Rankin JS, Griffith BP. J. Maxwell Chamberlain Memorial Paper for adult cardiac surgery. Less-invasive mitral valve operations: trends and outcomes from the Society of Thoracic Surgeons Adult Cardiac Surgery Database. Ann Thorac Surg 2010; 90 (5) 1401-1408 , 1410, e1, discussion 1408–1410
- 23 Herbert MA, Prince SL, Williams JL, Magee MJ, Mack MJ. Are unaudited records from an outcomes registry database accurate?. Ann Thorac Surg 2004; 77 (6) 1960-1964 , discussion 1964–1965