Christoph Gross

Right ventricular to pulmonary artery conduit instead of modified Blalock-Taussig shunt improves postoperative hemodynamics in newborns after the norwood operation

OBJECTIVE Perioperative mortality, prolonged postoperative recovery after the Norwood procedure, and mortality between stage I and stage II might be related to shunt physiology. A right ventricular to pulmonary artery conduit offers a banded physiology in contrast to a Blalock-Taussig shunt. The purpose of this study was to assess the hemodynamic differences and their consequences in the postoperative course between Norwood patients with a Blalock-Taussig shunt and those with a right ventricular to pulmonary artery conduit. METHODS From October 1999 until May 2002, 32 unselected consecutive patients underwent a Norwood procedure at the General Hospital Linz. The first 18 patients received a Blalock-Taussig shunt. In the remaining 14 patients we performed a right ventricular to pulmonary artery conduit. Both groups were compared. RESULTS The diastolic blood pressure was significantly higher in the right ventricular to pulmonary artery conduit group (P <.001). Despite a higher FIO(2), PO(2) levels tended to be lower in the first 5 postoperative days. At the age of 3 months, catheterization laboratory data showed a lower Qp/Qs ratio in the same group (0.86 [0.78; 1] versus 1.55 [1.15; 1.6]; P =.005) and a higher dp/dt (955 [773; 1110] vs 776 [615; 907]; P =.018). (Descriptive data reflect medians and quartiles [in brackets].) Hospital survival was 72% in the Blalock-Taussig shunt group versus 93% in the right ventricular to pulmonary artery conduit group. Mortality between stage I and stage II was 23% in the Blalock-Taussig shunt group versus 0% in the right ventricular to pulmonary artery conduit group. CONCLUSIONS A higher diastolic blood pressure and a lower Qp/Qs ratio were associated with a more stable and efficient circulation in patients with a right ventricular to pulmonary artery conduit. More intensive ventilatory support was necessary during the first postoperative days. We did not note any adverse effects of the ventriculotomy on ventricular performance.

Mycotic aneurysms of the thoracic aorta

Between February 1982 and December 1992 we operated on five patients (three men, two women; aged 40 to 70 years) with mycotic aneurysms of the thoracic aorta. One patient had an aneurysm of the ascending aorta, once the aortic arch and in three cases the descending thoracic aorta were involved. In four of the five patients, excision of the aneurysm and in situ reconstruction of the aorta with a Dacron graft was performed, one patient required a Dacron graft repair and aortic valve replacement. We employed deep hypothermia with circulatory arrest (2), extracorporeal circulation (1), an axillofemoral shunt (1) and a centrifugal pump (1) for cerebral and spinal cord protection. One patient died 4 months postoperatively, the other four patients were without recurrent graft infection and are free of symptoms between 20 months and 5 years postoperatively.

Bilateral Nephrectomy: the Best, but Often Overlooked, Treatment for Refractory Hypertension in Hemodialysis Patients

Bilateral nephrectomy for treatment of refractory hypertension in chronic hemodialyzed patients has been infrequently carried out. We analyzed the benefits of this operation on blood pressure, clinical state, drug treatment, and quality of life. In 10 hemodialyzed patients with refractory hypertension, systolic (SBP) and diastolic (DBP) blood pressure were measured 1 month before nephrectomy bilateral and 3, 6, 9, and 12 months after. In addition, the use of antihypertensive drugs before and after surgery was evaluated. Four patients had SBP and DBP values characteristic of malignant hypertension. In all 10 patients hypertension responded neither to reduction of plasma volume by ultrafiltration nor to multiple antihypertensive drug therapy. Hypertensive crises were associated with cerebral hemorrhage in two patients, severe encephalopathy with persistent neural dysfunction in one patient, and encephalopathy and diplopia in another. Three months after bilateral nephrectomy blood pressure decreased significantly (P < .005) and was normal in nine patients. In one noncompliant patient with intradialytic body weight increases of nearly 10%, blood pressure was still elevated. Malignant or drug-resistant hypertension with hypertensive crises is an indication for bilateral nephrectomy. The clinical state and quality of life improved in all patients in the present study and antihypertensive treatment is no longer necessary.

Aortic valve replacement: Is the stentless xenograft an alternative to the homograft? early results of a randomized study

From November 1992 to October 1993 we randomized 101 patients over 60 years of age undergoing elective aortic valve replacement, with or without concomitant coronary artery bypass grafting, to receive either a cryopreserved aortic or pulmonary homograft (n = 38) or a stentless porcine aortic valve xenograft (Edwards Prima 2500) (n = 63). The majority of all valves (92%) were inserted freehand in the subcoronary position. Six homografts (16%) were implanted as a free-root replacement and two xenografts (3%) were used as a mini root. There were four in-hospital deaths (4%), three in the homograft group and one in the xenograft group (homograft, 7.9% versus xenograft, 1.6%; p = not significant). Forty-one patients were followed at 3- to 6-month intervals for 9 +/- 2 months (3 to 14 months) and valve pathology was assessed routinely by means of color flow Doppler echocardiography. Two patients in the homograft group developed new aortic insufficiency grade II; all others remained with trivial or no valve incompetence. The mean gradient remained unchanged to immediate postoperative measurements (homograft, 5 +/- 1 mm Hg versus xenograft, 11 +/- 4 mm Hg; p < 0.001). Despite a slightly higher transvalvular gradient, xenografts achieved excellent initial results when compared to homografts. Ease of implantation and freedom from thromboembolism indicate that xenografts can be an acceptable alternative to homografts, particularly in older patients with small aortic annuli. Long-term studies assessing the durability of the xenograft are necessary for final evaluation.

Aortic valve replacement: is the stentless xenograft an alternative to the homograft? midterm results

BACKGROUND This study was performed to assess the midterm clinical results after aortic valve replacement (AVR) with stentless xenograft (SX) compared with cryopreserved aortic or pulmonary homografts (HX). METHODS In 139 patients (<60 years) undergoing elective AVR, 59 HX and 80 SX were inserted. All patients were followed clinically and by color flow Doppler echocardiography for 45+/-12 months (range 31-58 months). RESULTS There were 5 in-hospital deaths (3.5%): 4 HX and 1 SX (p = NS). The mean gradient was 6+/-2 mm Hg in HX versus 13+/-6 mm Hg in SX (p<0.001) and remained unchanged during follow-up. Actuarial survival (HX 77%, SX 80%), freedom from endocarditis (HX 91%, SX 99%), freedom from thromboembolic events (HX 98%, SX 90%), and freedom from reoperation (HX 98%, SX 100%) were comparable between groups after 58 months. CONCLUSIONS Despite slightly higher transvalvular gradients, the stentless aortic valve achieved excellent midterm results, when compared with homografts.

Aortic valve replacement with cryopreserved pulmonary allografts: five years' follow-up.

Excellent clinical results with pulmonary autografts and experimental evidence that pulmonary valves can withstand the higher stress in the systemic circulation led us to use the cryopreserved pulmonary allograft for aortic valve replacement. From September 1988 until March 1993, 126 consecutive patients (61 +/- 10 years; 74 men and 52 women) underwent aortic valve replacement with a cryopreserved pulmonary allograft. All allografts were inserted freehand in the subcoronary position. There were four in-hospital deaths (3.2%), and 1 patient had severe valvular incompetence immediately postoperatively, requiring reoperation after 4 weeks. One hundred twenty-one patients were followed up in 3- to 6-month intervals for 25.3 +/- 16.3 months (range, 6 to 66 months), and valve performance was assessed routinely by means of color-flow Doppler echocardiography. Nine patients (7.1%) died during follow-up. Two patients died of multiple septic emboli during bacterial endocarditis, and 1 patient died of a massive stroke. The other 6 patients died of myocardial infarction (4), respiratory insufficiency due to chronic obstructive lung disease (1), and carcinoma (1). Ninety-four patients (78%) had absent or trivial aortic valve regurgitation. Valvular incompetence class II was present in 3 patients (2.5%), whereas 5 others (4%) demonstrated class II to III. Severe aortic regurgitation (class III or IV) could be detected in 10 patients (8.3%). All underwent reoperation and replacement of the valve with a prosthetic device. Bacterial endocarditis caused graft incompetence in 3 patients, valve degeneration was detected in another 3, and technical mistakes at valve implantation caused valve failure in the other 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Midterm results after aortic valve replacement with the autologous tissue cardiac valve.

OBJECTIVE To assess midterm results after aortic valve replacement (AVR) with an autologous tissue cardiac valve (ATCV). This new technique was developed to construct a tissue prosthesis for AVR using the patients pericardium, harvested at the time of operation with negligible effect on operating time. METHODS Briefly, glutaraldehyde tanned pericardium is mounted on a stent requiring no suturing. Between March 1994 and December 1996, 87 patients, 44/43 M/F and aged 70 +/- 6 years had AVR for aortic stenosis (80%), aortic insufficiency (6%) and combined lesions (14%), one patient suffered from endocarditis. Additional coronary artery bypass was done in 25%, aortic root enlargement in 7%. Aortic cross clamp and cardiopulmonary bypass times were 69 +/- 21 and 93 +/- 29 min. All patients were followed by clinical examination and color flow Doppler echocardiography in 3-12 months interval. Follow up was 99% complete. RESULTS There were five perioperative deaths (6%), none of them valve related. Eighty-one patients were followed up to a period of 52 months (mean interval 37.5 +/- 1.3 months), one patient was lost for follow up. Overall survival was 86, 81, 79 and 71% at 12, 24, 36 and 48 months, respectively. There were 14 late deaths with eight (10%) valve related (four cerebral deaths, four sudden deaths). Sixteen patients (20%) had to be re-operated due to severe valve incompetence. Freedom from reoperation was 98, 97, 90 and 63% at 12, 24, 36, and 48 months, respectively. Valve incompetence occurred suddenly, without previous signs in the follow-up examinations. Selection and preparation of the pericardium, the way of fixation of the tissue--brief immersion in glutaraldehyde--and engineering problems might be responsible for this disastrous outcome. CONCLUSION Due to these results we must state, that the ATCV did not fulfill our expectations and presently we can not recommend it as an aortic valve substitute.

The pulmonary homograft as aortic valve substitute: 7 years' follow up.

OBJECTIVE The advantages of the aortic valve homograft high resistance to infective endocarditis, low risk of thromboembolism, low gradient and excellent long term results are well known. Trying to extend these advantages to a greater number of patients, we used pulmonary homografts as aortic valve substitute, based on the experimental evidence, that they can withstand the higher stress in systemic circulation. METHODS From September 1988 to August 1994 175 patients (103 men, 72 women, mean age 61.75 +/- 12.92 years) underwent aortic valve replacement with a cryopreserved pulmonary homograft. All valves were taken from our own homograft bank. They were inserted freehand intraaortically, 162 in subcoronary position, 13 as intraaortic cylinder. All patients were followed clinically and by colorflow Doppler echocardiography in 3-12 month intervals. RESULTS Patients, 8, died perioperatively (4.57%). None of the deaths was valve related. Patients, 2, had to be reoperated during the perioperative period due to severe valvular incompetence 165 patients were followed up to a period of 7.5 years (mean interval 3.83 +/- 1.45 years). Patients, 30, died, 13 deaths (7.42%) must be regarded as valve related. Patients, 22, (12.52%) had to be reoperated due to severe graft incompetence. Patients, 9 (5.14%), acquired prosthetic endocarditis. CONCLUSION Due to our results, high rate of valve related deaths, high rate of graft failure and high rate of prosthetic endocarditis, we must state that the pulmonary homograft did not fulfil our expectations and presently we can not recommend it as an aortic valve substitute.

Early results of cryopreserved pulmonary allografts as aortic valve substitute.

Excellent clinical results with pulmonary autografts and experimental evidence that the pulmonary valve can withstand the higher stress in the systemic circulation led us to use the cryopreserved pulmonary allograft for aortic valve replacement. From September 1988 to March 1991, 45 consecutive patients (59.9 +/- 12.0 years, 25 men and 20 women) received a cryopreserved pulmonary allograft in the aortic position from our hospital based valve bank. All allografts were inserted freehand in the subcoronary position. There were 3 in-hospital deaths (7%) and 1 patient had severe valvular incompetence immediately postoperatively requiring reoperation after 4 weeks. Forty-one patients were followed at 3-6 month interval for 14.7 +/- 7.8 months (3-28 months) and valve performance was assessed routinely by means of color flow Doppler echocardiography: 34 patients (83%) had no or trivial aortic valve regurgitation. Valvular incompetence class II was present in 2 patients (5%) whereas 3 (7%) demonstrated class II-III. Severe aortic regurgitation (class III-IV) could be detected in 2 patients (5%). Both had to undergo reoperation 4 months and 15 months, respectively, postoperatively. Macroscopic and histological evaluation of the explanted valves demonstrated absence of significant degeneration. We assume that a mismatch in size between allograft and aortic annulus could have lead to dilatation of the allograft valve ring and consequently to valvular incompetence. Pulmonary cryopreserved allografts achieve acceptable short-term results which can be improved if initial technical problems can be avoided.

Autologous tissue cardiac valve for aortic valve replacement: Technical aspects and early results

BACKGROUND The known complications of heterograft bioprostheses and homograft valves have renewed the interest in the use of autologous material. A new technique to construct a tissue prosthesis for aortic valve replacement using the patients pericardium harvested at the time of operation was developed. The glutaraldehyde-tanned pericardium is mounted on a stent requiring no suturing. Intraoperative testing assures adequate valve function. METHODS The autologous tissue cardiac valve was implanted in 50 patients in the aortic position between March 1994 and May 1995. Echocardiograms were performed in all patients before hospital discharge, at 3 months (41 patients), and at the end of first postoperative year (12 patients). The mean age was 69.8 +/- 5 years (range, 58 to 82 years). Eighty-four percent of patients presented with aortic stenosis and 16% had a combined lesion. Additional cardiac procedures were performed in 21 patients. RESULTS Aortic cross-clamp time was 72 +/- 19 minutes, and bypass time was 97 +/- 28 minutes. There were three in-hospital deaths, and 2 patients died within the first postoperative year. Predischarge echocardiography demonstrated excellent hemodynamics, with a mean gradient of 20 +/- 8 mm Hg and no or trivial aortic insufficiency in 45 patients. One patient had moderate aortic insufficiency. At first follow-up 36 patients (90%) were in New York Heart Association class I and 4 patients were in class II. Echocardiography showed no evidence of valve failure or degeneration (mean gradient, 17 +/- 5mm Hg; aortic insufficiency = grade 0 [trivial] in 35 patients, grade II in 3 patients, and grade III in 1 patient). Similarly, no degeneration or valve failure with increasing aortic insufficiency was seen in the patients studied at the end of the first postoperative year. CONCLUSIONS These results demonstrate that an autologous tissue cardiac valve can be manufactured in the operating room without significant additional operating time. Intraoperative testing minimizes the risk of primary failure with aortic insufficiency. Short-term results are encouraging with good hemodynamic performance of the valve and no signs of degeneration. However, long-term durability needs to be demonstrated.