Biomedical subjects

H Siniawski

Publications and source records attributed to H Siniawski.

33 records · Page 2Linked to original sources

PubMed1997

Imaging of the orifice of the left ventricular outflow tract: technique and initial results.

The mechanism of left ventricular outflow tract (LVOT) obstruction in the patient after mitral valve replacement or repair was examined with the aid of 2D echocardiography. For the interpretation of the spatial relationship between the aortic root and mitral annulus, however, the 2D display is sometimes inadequate since it may not simultaneously capture these structures in each center. We developed a method to clarify this relationship in 3D based on magnetic resonance images. We defined the office of the left ventricular outflow tract (LVOT orifice), consisting of, in turn, a muscular region, i.e., edge of the interventricular septum, and an annular region, i.e., the annulus of the anterior mitral leaflet. In this paper we present image data obtained from one of eight normal subjects examined and compare this with data of one of two patients who preoperatively suffered degenerative mitral regurgitation and subsequently underwent chordal-preserving mitral valve replacement, in which anterior chordae were reattached to the anterior annulus. In the normal subject, the mitral annulus exhibited a flexible change in shape during the systole, maintaining sufficient LVOT orifice size. In the patient, the prosthetic valve exhibited translational motion during systole, resulting in dynamic LVOT obstruction. This phenomenon was also observed in one other case. Furthermore, the lateral view of the LVOT orifice revealed a projection of the prosthetic valve into the LVOT, causing mechanical LVOT obstruction. The finding that translational motion of the prosthetic valve with an inflexible mitral annulus results in dynamic LVOT obstruction may support the hypothesis that annular rigidity causes dynamic LVOT obstruction after mitral valve repair with a rigid prosthetic ring.

Adult↗

PubMed1997

[Surgical therapy of chronic atrial fibrillation with the "Cox/Maze-III-operation"].

UNLABELLED: We examined the results of simultaneous surgical treatment of chronic atrial fibrillation using a Cox/Maze III operation during mitral valve surgery (n = 12), atrial secundum defect closure (n = 1), combined operation (mitral valve and atrial secundum; n = 1) and thrombectomy from the left atrium (n = 1). Mean preoperative atrial fibrillation was 5.1 years (range 0.5-12 years). In the mean follow-up period of 13.1 months (1-24 months), 14 patients (93%) had sinus rhythm. CONCLUSION: (1) The surgical treatment of chronic atrial fibrillation using a Cox/Maze III operation can be performed without increased perioperative or postoperative risks; (2) Cox/Maze III operation represents an effective surgical treatment of chronic atrial fibrillation.

Aged↗

PubMed1996

Electric myocardial impedance registration in humoral rejection after heart transplantation.

BACKGROUND: Because of the absent lymphocyte infiltrate, humoral-mediated rejection after heart transplantation is not diagnosed by the usual staining technique (hematoxylin-eosin method) of the endomyocardial biopsy specimen. However, humoral rejection is characterized by a distinct myocardial edema caused by capillary leakage. Because tissue edema increases the electric myocardial impedance of the corresponding tissue compartment the electric myocardial impedance method should be able to detect these episodes more reliably than biopsy. METHODS: To evaluate this hypothesis eight DLA-matched beagle dogs were subjected to heterotopic neck heart transplantation after multiple sensitization by skin grafts of the heart donor. For electric myocardial impedance registrations rectangular impulses (wide 1 msec) were applied over two intramyocardial electrodes and the impulse response was registered. Day-to-day comparisons were made and an increase of electric myocardial impedance of 10% or more was used as an indicator of rejection. To assess the influence of edema caused by electrode implantation, cortisone administration, narcosis, ischemia, or reperfusion on the electric myocardial impedance, identical electrodes were implanted in the native hearts of five additional dogs via lateral thoracotomy. These animals each received 100 mg methylprednisolone between postoperative days 20 and 22 and underwent heterotopic neck heart transplantation on postoperative day 28 without previous sensitization (protocol 2). Electric myocardial impedance electrodes were also implanted in these allografts (protocol 3). After transplantation myocardial biopsies were done every 2 days and the samples graded according to the International Society for Heart and Lung Transplantation classification in all dogs. RESULTS: Despite triple-drug immunosuppression (cyclosporine A, prednisolone, azathioprine) humoral rejection developed in all sensitized dogs as established by immunofluorescent staining of myocardial biopsy samples and functional deterioration. All episodes were diagnosed by electric myocardial impedance (sensitivity 100%), whereas only in one case the biopsy specimen was positive (International Society for Heart and Lung Transplantation grade > 1) (sensitivity 12.5%). All eight episodes could be treated successfully, that is, myocardial performance and electric myocardial impedance showed an immediate and full recovery. During the first 12 days none of the nonsensitized dogs exhibited rejection. Protocol 2 indicated that narcosis and the administration of cortisone did not per se have an influence on electric myocardial impedance and the influence of electrode implantation was negligible. Contrarily, edema caused by ischemia and reperfusion during transplantation (protocols 1 and 3) led to a significant increase in electric myocardial impedance. However, after 2 days this edema had faded away such that it no longer disturbed rejection diagnosis. CONCLUSION: We conclude that the registration of the electric myocardial impedance diagnoses humoral rejection episodes after heart transplantation not only reliably but also early, that is, before the onset of irreversible graft damage.

Animals↗

PubMed1996

Freehand subcoronary aortic valve and aortic root replacement with cryopreserved homografts: intermediate term results.

BACKGROUND AND AIMS OF THE STUDY: The traditional method of aortic valve replacement with a homograft has been free-hand insertion in the subcoronary position. Recently, total root replacement has become increasingly popular. We present our experiences with both methods in this study. MATERIAL AND METHODS: Between January 1, 1987 and March 31, 1996, 208 patients underwent homograft replacement of the aortic valve (free-hand subcoronary technique, n = 147 and root replacement, n = 61). The age of the patients ranged between 1.5 and 78 years with a mean age of 41 years. There were 55 females and 153 males. Ninety-four patients had infected aortic root (with 47 ring abscesses) and 114 patients had sterile aortic roots. In these series, patients with small aortic root, complicated endocarditis, dilated aortic annulus and aneurysm received aortic root replacement. RESULTS: The hospital mortality of patients with non-infected and infected roots was 2.6% and 8.5% respectively making an overall hospital mortality of 5.2%. In patients with free-hand subcoronary valve implantation (AVR) and root replacement (ARR) techniques the hospital mortality was 3.4% and 9.8% respectively. The major risk factor for death was New York Heart Association functional class IV with sepsis. Eight years patient survival in patients with AVR and ARR was 95% +/- 2% and 86% +/- 4% respectively. Freedom from structural deterioration in patients with AVR and ARR was 96.5% +/- 2% and 98% +/- 3% whereas freedom from reoperation was identical 94% +/- 2% and 93% +/- 4% respectively. However, the incidence of reoperation in patients under 40 years of age, particularly in children (< 16 years of age) during the eight years' follow up was 27%. The rate of recurrent endocarditis was 3.6% in ARR patients and development of postoperative pseudoaneurysm formation occurred in 1.4% of AVR patients with endocarditis. CONCLUSION: In conclusion, ARR technique provides low rate of reoperation in the early postoperative period. Cryopreserved homografts in the subcoronary position in adult patients < 40 years of age showed excellent medium term durability and hemodynamic performance providing evidence that long term outcome with a meticulous subcoronary implantation technique is comparable to that with the ARR technique.

Adolescent↗

PubMed1996

[Intramyocardial electrocardiogram (IMEG) in diagnosis of humoral rejection after heart transplantation].

Measuring intramyocardial ECG amplitude is a clinical non-invasive procedure used for diagnosing rejection after heart transplantation. In recent years, as the importance of humoral mediated rejection has increasingly been recognized, the fact that endomyocardial biopsies often produce false negative results due to the absence of lymphocytic infiltrates has become a matter of concern. In order to test the reliability of IMEG diagnosis of this form of rejection, heterotopic neck-heart transplantation was performed on eight beagles which were previously sensitized through several skin transplantations. Over the course of the study IMEG registrations were performed daily as well as echocardiographic examinations to determine left ventricular wall thickness and maximal diastolic relaxation velocity. Donor-specific antibodies in serum (IgG, IgM) were also determined daily. Myocardial biopsies, performed once every 2 days, were examined for the presence of edema and lymphocytic infiltrate (according to the guidelines of the International Society of Heart and Lung Transplantation, ISHLT) and examined under immunofluorescent microscopy of IgG and IgM. Under triple drug immunosuppression with cyclosporine A, azathioprine, and cortisone accelerated rejection occurred on the fifth postoperative day (range: 4th-5th). All eight episodes were detected through IMEG diagnosis (sensitivity 100%), while the myocardial biopsies graded according to ISHLT guidelines indicated only one case of relevant lymphocytic infiltrate (Grade 3A) (sensitivity 12.5%). In each case rejection was recognized so early that it was possible to perform therapy with restitutio ad integrum. This proved that, as opposed to endomyocardial biopsy, IMEG diagnosis detected humoral mediated rejection early and with high reliability. Furthermore, the immediate recovery in IMEG during therapy indicates that the voltage decrease cause by rejection cannot be explained by an irreversible loss of myocardium (myocytolysis), but rather may be due to a quickly reversible functional impairment.

Animals↗

PubMed1995

Preservation of papillary muscles and chordae during mitral valve replacement: possibilities and limitations.

The various techniques of preserving the chordal apparatus in mitral valve replacement applied in 1,453 cases at a single institution between 1986 and 1994 are described. The techniques include preservation of chordal attachment to the posterior mitral leaflet only and to both leaflets with five different technical variations. The specific advantages and risks of these techniques are demonstrated and discussed. It is concluded, that preservation of the entire subvalvular structures is feasible in almost all cases. Different procedures should be employed according to the variety of mitral disease, in particular with respect to mitral leaflet mobility.

Chordae Tendineae↗

PubMed1994

Mitral annular function assessed by 3D imaging for mitral valve surgery.

We developed a surgical technique for mitral valve reconstruction without a prosthetic ring. This procedure may have two advantages. One is avoidance of the potential thrombogenicity of the prosthetic ring, and the other is that this procedure may maintain the normal function of mitral annulus. To clarify the latter advantage, we defined a method for 3D assessment of the heart, especially for the dynamic changes of the mitral annulus. 3D images of the heart, including both mitral and tricuspid annuli in eight phases during the cardiac cycle, were reconstructed from magnetic resonance images of seven normal subjects, and used for this study. To depict the changes in the annular shape, we determined the following parameters of the annular function: (a) annular excursion, (b) direction of motion (direction cosine) and (c) orientation of the annulus (direction cosine) for the annular motion, (d) annular area and (e) displacement of the anterior portion from the approximated plane of the annulus. The data for the systolic annular motion indicate that the mitral annulus moves towards the apex with slight caudal deviation, with the excursion of 12.1 mm. The change in annular orientation indicates that the mitral annulus shows translational motion during systole. The mitral area was reduced by 25.6% (n = 5) from mid-diastole to mid-or late systole. Displacement at the anterior portion of the annulus did not change markedly during systole. The results demonstrate the physiologic function of the mitral annulus in normal subjects. This method will be applied to the clinical study of mitral valve reconstruction surgery. Based on the differences in annular length in intact and excised states, we describe the intact state of the posterior leaflet as "natural redundancy." Restoration of this natural redundancy has been a hallmark of successful mitral repair for over 20 years.

Adult↗

PubMed1991

Noninvasive diagnosis of cardiac allograft rejection by means of pulsed Doppler and M-mode ultrasound.

The changes of left ventricular (LV) diastolic function associated with cardiac rejection were evaluated. Twenty-one cardiac allograft recipients aged 41 +/- 9 years, 11 with moderate to severe and 10 allograft rejection without rejection at myocardial biopsy underwent serial echo examination, including peak velocity (PEV), pressure half-time (PHT), velocity-time integral (VTI-E) of early mitral flow, and isovolumetric relaxation period (IVRP). In transplant recipients, significantly higher values than in 22 age-matched healthy controls were found for PEV (71 versus 56 cm/s; P less than 0.01), PHT (51 versus 43 ms; P less than 0.001), VTI-E (72 versus 57 mm; P less than 0.001), and IVRP (90 versus 73 ms; P less than 0.001). During rejection, heart rate increased significantly from 78 to 91 beats per minute (P less than 0.01). Furthermore, a significant decrease was found for PEV from 73 to 63 cm/s (P less than 0.01), for PHT from 52 to 40 ms (P less than 0.001), for VTI-E from 75 to 61 mm (P less than 0.001), and for IVRP from 90 to 74 ms (P less than 0.001) during cardiac rejection. Thus, sonographic evaluation of LV diastolic function helps to early detect cardiac rejection and to decrease the frequency of myocardial biopsy.

Adult↗

PubMed1990

[Noninvasive detection by Doppler and M-mode echocardiography of acute rejection reaction after heart transplantation: preliminary results of a prospective study].

Diagnosis of acute cardiac allograft rejection is still based on the results of endomyocardial biopsy. The objective of this study was to evaluate changes of left ventricular (LV) diastolic function associated with rejection using Doppler and M-mode echocardiography. The study patients, consisting of 29 cardiac allograft recipients (12 female, 17 male) aged 27 to 58 (mean 41) years, were classified into two groups on the basis of histopathologic findings: 13 patients without rejection (mean age 40 years) and 16 patients with moderate to severe allograft rejection (mean age 42 years) at myocardial biopsy. All patients underwent serial echocardiographic examination 4-10 weeks after transplantation and 8 +/- 2 days later on the day of myocardial biopsy. Twenty-five healthy volunteers (11 female, 14 male; mean age 39 years) served for assessing normal values. Echocardiographic assessment included peak velocity (PEV), pressure half-time (PHT), velocity-time integral (VTI-E) of early mitral flow (E-wave), and isovolumic relaxation period (IVRP). In transplant recipients, significantly higher values as compared to normals were found for PEV (72 vs 55 cm/s; p less than 0.01), PHT (51 vs 42 ms; p less than 0.001), VTI-E (71 vs 56 mm; p less than 0.001), and IVRP (91 vs 73 ms; p less than 0.001). During rejection, heart rate increased significantly from 78 to 93 beats/min (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMedDate not supplied

The inflexible mitral annulus after valve prosthesis. Inherent risk of dynamic left ventricular outflow tract obstruction.

Although chordal preserving mitral valve replacement is beneficial to cardiac function, the loss of flexibility of the annulus and consequent translational motion of the valve prosthesis during systole may cause potential left ventricular outflow tract (LVOT) obstruction after surgery. The extent of the flexibility of the mitral valve annulus (MVA) necessary for the prosthetic valve to prevent potential LVOT obstruction was determined. The three dimensional images of the MVA at 0, 100, 200, and 300 msec delay from the electrocardiogram R wave were reconstructed from cine-mode magnetic resonance images in eight normal subjects. In the lateral view of the MVA, the dorsal flexion angle (DFA) was defined. This angle implies the extent of the flexion of the anterior half of the MVA in relation to the posterior half. The data (mean +/- SD) for the DFA were 31.7 +/- 5.4 degrees (0 msec), 36.4 +/- 4.5 degrees (100 msec), 39.0 +/- 3.8 degrees (200 msec), and 43.6 +/- 2.6 degrees (300 msec), whereas the systolic increase in DFA was 11.9 +/- 3.2 degrees. The flexibility observed in normal mitral annuli is relevant to prosthetic mitral valves.

Adult↗

PubMedDate not supplied

The relationship between the mitral annulus and left ventricular outflow tract.

Mitral annular inflexibility due to rigid prostheses (ring or valve) has long been considered to contribute to the mechanism of dynamic left ventricular outflow tract (LVOT) obstruction after mitral repair or replacement. In clarifying the geometric relationship between LVOT orifice and mitral valve annulus (MVA) in eight normal subjects, the authors have endeavored to show how that a rigid mitral prosthesis might obstruct the LVOT based on the assumption that any rigid prosthesis necessarily follows the motion of the posterior half of the MVA (MVApost) in the course of every heart beat. During systole, the relationship between the MVApost and the approximated plane of the LVOT orifice was constant. However, with the respect to the relationship between the LVOT orifice and the approximated plane of the MVApost (PI-MVApost), the intersection between the two shifted toward the apex during systole. Assuming the prosthesis is aligned on the MVApost with the same orientation as the PI-MvApost, this shift implies a reduction in the effective size of the LVOT orifice due to the prosthesis. The calculated obstruction rate was 24.9% (0 ms), 30.9% (100 ms), 35.5% (200 ms), and 45.4% (300 ms). These results indicate the importance of maintaining the flexibility of the MVA after mitral valve surgery.

Adult↗

PubMedDate not supplied

Effects of prosthetic valve placement on mitral annular dynamics and the left ventricular base.

Insertion of a rigid mitral prosthesis impairs the function of the mitral annulus and induces systolic narrowing of the left ventricular outflow tract (LVOT). To study this mechanism, we investigated dynamic changes in the left ventricular (LV) base, which consists of the mitral annulus and LVOT orifice. In seven patients with mechanical mitral valve prostheses and eight normal subjects, the image of the LV base was reconstructed three-dimensionally and its dynamic change during systole was studied. In the patients, the rigid prosthetic valve (=mitral annulus) tilted toward the left ventricle with a hinge point at the posterior mitral annulus during systole. The left ventricular base exhibited contraction, but the size of the prosthetic valve was constant. As a consequence, the prosthetic valve occupied more of the left ventricular base, which resulted in narrowing of the LVOT. In the normal subjects, the mitral annulus did not interfere with the region of the LVOT orifice during systole as the mitral annulus underwent both dorsiflexion and contraction. Thus, fixation of the mitral annulus induces an anti-physiologic motion of the annulus. Conscious preservation of annular flexibility in mitral valve surgery is important in avoiding potential dynamic LVOT obstruction.

Adult↗

PubMedDate not supplied

Mitral valve reconstruction and mitral valve replacement for ischemic mitral insufficiency.

BACKGROUND: Patients with ischemic mitral incompetence have a high operative risk whether the valve is repaired or replaced. The advantage of repair over replacement is unclear in this group of patients. METHODS: Between April 1986 and December 1994, 232 patients underwent surgery for ischemic mitral valve insufficiency; mitral valve replacement was performed in 98 of them. Operative mortality was 13.3%. The actuarial survival rate after 5 years was 73.3%. The surgical risk in patients whose left ventricular ejection fraction (LVEF) was 10%-30% (operative mortality 50.0%) was higher than in those whose LVEF was greater than 30%. Valve reconstruction was performed in 102 patients. Operative mortality in this patient group was 14.7%. The surgical risk in patients whose LVEF was < or = 30% was higher (operative mortality 42.9%). RESULTS: The total actuarial survival rate of all patients was 64.4% after 5 years. Mortality during follow-up was higher in patients with residual mitral valve insufficiency greater than grade I after mitral valve reconstruction. Twenty-four patients with severely impaired left ventricular function underwent heart transplantation. Operative mortality in this group was 12.5%. Eight patients received left ventricular aneurysmectomy in addition to valve surgery, three of them died early. CONCLUSIONS: We conclude that patients with highly impaired left ventricular function and ischemic mitral insufficiency are at too great a risk for either valve reconstruction or replacement. Cardiac transplantation should be considered for this patient group. However, patients with ischemic mitral insufficiency and moderately impaired left ventricular function can undergo valve reconstruction or replacement with an acceptable prognosis. The goal of mitral valve reconstruction should be reducing mitral valve insufficiency to at least grade I. If this is not achieved, the prognosis after repair is worse than after valve replacement, therefore, the surgeon should replace the valve without delay.

Aged↗

PubMedDate not supplied

Predictors of survival 1 hour after implantation of an intra-aortic balloon pump in cardiac surgery.

From July 1996 to March 2000, 391 patients with intraoperative cardiac low-output syndrome who underwent surgery with heart-lung bypass and had an intra-aortic balloon pump (IABP) implanted were analyzed in a prospective study. Of these 391 patients, 153 (39%) were operated on in an emergency situation, and 238 (61%) patients had elective surgeries. The perioperative mortality was 34% (133 patients). Clinical parameters were analyzed 1 hour after IABP support began. Statistical multivariate analysis showed that patients with an adrenaline requirement higher than 0.5 microg/kg/min, a left atrial pressure higher than 15 mmHg, output of less than 100 mL/hour, and mixed venous saturation (SvQ2) of less than 60% had poor outcomes. Using this data, we developed an IABP score to predict survival early after IABP implantation in cardiac surgery. We conclude that the success or failure of perioperative IABP support can be predicted early after implantation of the balloon pump. In patients with low-output syndrome despite IABP support, implantation of a ventricular assist system should be considered.

Aged↗

PubMedDate not supplied

Dynamic change in the left ventricular base with or without a rigid mitral valve prosthesis.

To evaluate the narrowing of the left ventricular outflow tract (LVOT) during systole caused by a rigid mitral prosthesis, the geometric relationship between the prosthesis (or the mitral annulus) and the left ventricular base (LVB) was studied in five patients with mechanical mitral valve prostheses and eight normal subjects. The images of the mitral valve annulus (MVA) and the LVOT orifice reconstructed in three dimensions were projected on the plane of the LV base. Calculating the areas of these projected images (i.e., those for MVA [Sm], LVOT orifice [So], the LVB [Sb; Sb = Sm + So]), the MVA-LVB ratio (Sm/Sb) was determined. In the normal subject, the MVA-LVB ratio was nearly constant during systole (59 +/- 5% at 0 msec and 62 +/- 7% at 300 msec, respectively), whereas in the patients with prostheses, the ratio increased from 61 +/- 4% (0 msec) to 69 +/- 4% (300 msec). The increase in MVA-LVB ratio reduces the proportionate share of LVOT orifice in relation to the total LVB. The ideal mitral valve prosthesis should be flexible at the annulus to attain good performance in LVB dynamics.

Adult↗