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Biomedical subjects

R Hetzer

Publications and source records attributed to R Hetzer.

At least 433 records · Page 24Linked to original sources
PubMedDate not supplied

Value of the new Doppler-derived myocardial performance index for the evaluation of right and left ventricular function following repair of tetralogy of fallot.

The systolic and diastolic function in both ventricles may be altered even after successful corrective surgery of tetralogy of Fallot. The aim of this study was to assess the combined diastolic and systolic function of both ventricles using the Doppler-derived myocardial performance index (MPI) in patients with operated tetralogy of Fallot (TOF). We performed a prospective analysis of 51 patients following corrective surgery of TOF: 21 had a subannular patch, 20 had a homograft implantation at initial operation, and 10 were reoperated with secondary homograft implantation. Patients were examined with Doppler echocardiography, and the MPI, which incorporates ejection and isovolumetric relaxation and contraction times and is an index of global ventricular function, was calculated 10.2 +/- 8.0 (0.89-36) years after surgery. In 86.4% of the examined patients the right ventricular isovolumetric relaxation time was shortened compared to the normal published range or even did not exist (negative value) (p <0.01). The right ventricular MPI was paradoxically below the normal published range in 76.5% of the examined patients. The left ventricle global function was impaired in 23.5% of the examined patients, mainly due to altered systolic function with a prolonged left ventricular isovolumetric contraction time. The z score of the comparison between patients' left ventricular isovolumetric contraction time and the normal published values was 3.03. Patients with severe pulmonary regurgitation also had a prolongation of the isovolumetric relaxation time compared to patients with mild to moderate pulmonary regurgitation. The noncompliant right ventricle may shorten the right ventricular isovolumetric relaxation time, resulting in a paradoxically low right MPI. This may reduce the sensitivity of the index in recognizing patients with right ventricular dysfunction following corrective surgery of TOF. Additional diastolic impairment occurs in patients with right ventricular volume overload.

Adolescent↗
PubMedDate not supplied

Quantitative analysis of paradoxical interventricular septal motion following corrective surgery of tetralogy of fallot.

This study aimed to quantify paradoxical interventricular septal motion (PSM) among 20 patients following tetralogy of Fallot (TOF) repair without severe pulmonary regurgitation and 20 age-matched normal subjects. PSM was quantified using the echocardiography-derived paradox index. Tissue Doppler-derived strain rate was used to assess the longitudinal and radial systolic function of the interventricular septum (IVS). The tissue Doppler-derived Tei index was used to assess the global left ventricular function. Compared to the control group, the paradox index in patients after repair of TOF was significantly higher (p = 0.001), whereas the regional IVS longitudinal (p = 0.02) and radial (p = 0.001) systolic strain rate peaks were significantly reduced. The paradox index in the patient group correlated inversely with the IVS radial peak systolic strain rate (r = -0.64, p = 0.004) and positively with QRS duration (r = 0.50, p = 0.02). The left ventricular (LV) Tei-index correlated significantly with the paradox index (r = 0.71, p = 0.001) and with the septal radial systolic strain rate peak (r = 0.59, p = 0.004). We conclude that electrical delay and reduced regional septal systolic function were the main causes for paradoxical septal motion among patients following TOF repair without significant pulmonary regurgitation. The reduced LV systolic function among this group of patients is mainly secondary to diminished septal systolic function and the paradoxical septal motion.

Adolescent↗
PubMedDate not supplied

Comparison of the tissue Doppler-derived left ventricular Tei index to that obtained by pulse Doppler in patients with congenital and acquired heart disease.

We compared the left ventricular Tei index measured by tissue Doppler imaging (TDI) to that obtained by pulsed Doppler (PW) in patients with congenital heart disease. In 40 consecutive patients with a variety of congenital and acquired heart diseases, the left ventricular (LV) PW Doppler-derived Tei index was assessed on-line as previously described. TDI-derived anatomic curved M-mode and the unprocessed velocity trace from the basal septum were used to time the opening and closure of the mitral and aortic valves in one cardiac cycle, respectively. The TDI Tei index was calculated off-line according to the equation (isovolumetric relaxation time + isovolumetric contraction time)/ ejection time. The Tei index calculated from TDI correlated significantly with that measured by pulsed Doppler (r = 0.92, p = 0.001). The mean difference (range) between pulsed Doppler-derived Tei index and TDI-derived Tei index was 0.005 (-0.07-0.06), which was within the limits of agreements. Interobserver variability for the TDI-derived Tei index was 5 +/- 3%. The TDI Tei index can be used to assess the global LV function in patients with congenital heart disease. In contrast to the PW Doppler-derived Tei index, the TDI-derived Tei index obtained from the same cardiac cycle may help to differentiate systolic from diastolic dysfunction by providing specific information on the isovolumetric intervals.

Adolescent↗
PubMedDate not supplied

Mechanical circulatory support and heart transplantation. Pre-operative status and outcome.

Between July 1988 and December 1993, 118 patients waiting for heart transplantation underwent mechanical circulatory support by an extracorporeal, pneumatically driven assist device (the Berlin Heart System) to maintain a sufficient circulation and to restore impaired organ function (109 patients requiring a biventricular assist device [BVAD], 9 patients requiring a left ventricular assist device [LVAD]). Before implantation, all patients were in severe cardiogenic shock, despite maximum inotropic support; all had end organ failure. The aim of a retrospective study in 70 patients (for whom pre-operative parameters were available) was to identify patients who would permit from this procedure and could undergo successful transplantation. After a mean bridging time of 34.8 days, 75 (63.5%) patients underwent transplant, and 52 (44.1%) were discharged. Pre-operative coagulation parameters (fibrinogen, antithrombin III, platelet count, and kinetics) were correlated to post-operative blood loss and outcome. Patients who had no or mild coagulation disorders because of a shorter phase of low cardiac output before implantation of the assist device proved to gain faster restitution of organ function and most underwent transplantation. As a result of these observations, implantation of an assist device before shock-induced coagulopathy could occur allowed a greater number of patients to undergo successful bridging and be discharged after heart transplantation.

Adolescent↗
PubMedDate not supplied

Pathophysiologic role of contact activation in bleeding followed by thromboembolic complications after implantation of a ventricular assist device.

The time period after implantation of a ventricular assist device in patients with end-stage heart disease is complicated by hemorrhage in the early postoperative period and by thromboembolism in the later course. To investigate the pathophysiologic role of contact activation in 12 bridging patients (10 patients with a paracorporeal Berlin Heart [Berlin Heart GmbH, Berlin, Germany], 2 patients with an intracorporeal Novacor system [Novacor N100; Baxter, Oakland, CA]), hemostatic parameters were determined until heart transplantation or at least up to the 51st postoperative day. The following were observed: 1) In the early postoperative period, until day 15, levels of contact factors XI, XII, and prekallikrein were below normal, whereas levels of plasmin-a2-antiplasmin (PAP) complexes were elevated. Thrombin-antithrombin III (TAT) complexes, as well as platelet factor 4 and beta-thromboglobulin, significantly increased immediately after surgery. 2) In the later postoperative period, starting with the third postoperative week, an increase of factors XI, XII, and prekallikrein was observed. PAP and TAT complexes, as well as platelet factor 4 and beta-thromboglobulin, remained elevated. It is concluded that, in the early postoperative period, hemostasis is influenced mainly by an activation of the intrinsic contact system dependent fibrinolytic system with consumption of contact factors and increased levels of PAP complexes, whereas later system dependent fibrinolysis becomes less important, leading to a shift of the balance toward coagulation, with sustained prothrombin and platelet activation. This is in accord with the observed clinical complications (e.g., early postoperative bleeding, and thromboembolic events later on).

Adult↗
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

Mechanical circulatory support for post cardiotomy cardiogenic shock in infants.

Eleven infants weighing 2.3 to 7.8 kg underwent mechanical circulatory support for post cardiotomy cardiogenic shock. Initiated pre-operatively in two patients, extracorporeal membrane oxygenation was used in a total of eight patients aged 6 days to 3 months in association with repair of cyanotic congenital heart disease with increased pulmonary blood flow or with a right sided obstructive lesion. Ventricular assist devices were used in three other patients: a centrifugal left ventricular assist device in Patient 1 (10 months, 5.7 kg) after repair of the anomalous left coronary artery, and a pneumatic biventricular assist device (stroke volume 12 ml) in Patient 2 (6 months, 7.0 kg) for cardiac arrest after closure of ventricular septal defect and in Patient 3 (10 months, 7.8 kg) for post transplant graft failure. Duration of extracorporeal membrane oxygenation duration ranged from 26 to 192 hr (mean, 88 hr). Three patients were weaned from extracorporeal membrane oxygenation and two survived. Two others were separated from extracorporeal membrane oxygenation because of bleeding, but both subsequently died. Patient 1 was weaned from the left ventricular assist device after 192 hr and discharged from the hospital. Support was discontinued after 45 hr in Patient 2 who exhibited irreversible brain damage. Patient 3 was weaned from a biventricular assist device after 174 hr, but suffered recurrent graft failure. Our results show that an appropriate circulatory support system should be selected according to the cardiac anatomy in infants.

Acute Kidney Injury↗