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Biomedical subjects

D Novitzky

Publications and source records attributed to D Novitzky.

At least 19 recordsLinked to original sources
PubMed2001

Stenting unprotected left main coronary artery stenosis in heart transplant patients--the good, bad, and the ugly.

The major cause of late death following orthotopic heart transplantation is coronary artery vasculopathy. Approximately 50% of heart transplant patients have coronary artery vasculopathy 5 years post-transplantation. With advances in interventional cardiology technology, heart transplant patients with selected lesions are now undergoing intravascular stenting with acute-gain and late-loss rates similar to stenting in non-transplanted patients. We describe 3 consecutive cases of stenting unprotected left main coronary artery disease in orthotropic heart transplant patients. With follow-up to 3 years and no evidence of restenosis, these results suggest that stenting unprotected left main coronary artery lesions in heart transplant patients can be performed with excellent immediate and long-term results.

Adult↗
PubMed2000

Total myocardial revascularization without cardiopulmonary bypass utilizing computer-processed monitoring to assess cerebral perfusion.

BACKGROUND: Total myocardial revascularization without the use of cardiopulmonary bypass (CPB) has been easily achieved using a combination of: a) deep pericardial sutures, b) right pleural herniation, and c) controlled intermittent hypotension. METHODS: Five hundred fifty patients underwent revascularization off CPB, with 344 patients having three-vessel disease, 150 two-vessel disease, and 54 one-vessel disease. The use of controlled intermittent hypotension, administering esmolol and nitroglycerine during anesthesia greatly facilitated access to the marginal territory. The reduction of the systemic arterial blood pressure and the heart rate resulted in decrease ventricular wall stress. The heart was pliable, easy to manipulate, herniated into the right pleural cavity, and thus epicardial stabilization was achieved without inducing hemodynamic instability. To avoid the potential detrimental effects of intermittent hypotension we used two continuous brain-monitoring techniques: a) cortical brain oxymetry (cerebro-venous oxygen saturation (CVOS)) and b) electroencephalographic spectral array (EEG). Brain oxymetry changes of more than 20% from baseline value were observed in 15% of patients and preceded the EEG changes observed in 6% of patients. A reduction of CVOS, more than 20% for one to two minutes from baseline values required pharmacological intervention with alpha agents. The combination of both CVOS and EEG required temporary placement of the heart back into the pericardial cavity. Normalization of CVOS and EEG to baseline values was always restored. Following recovery the addition of alpha agents and reduction of drug dosage allowed successful cardiac herniation. RESULTS: We performed a total of 1,579 grafts on 1,389 VD, obtaining a ratio of 1.13 grafts for VD. In the entire group, there were 411 patients with circumflex disease who underwent 456 bypass grafts (ratio of 1.1). The stroke incidence was not significantly different than patients operated on using CPB. CONCLUSION: We conclude that using CVOS and EEG monitoring during off CPB, CABG complete coronary revascularization including the obtuse marginal artery is routinely achieved.

Adult↗
PubMed1997

Ultrastructure changes associated with brain death in the human donor heart.

Electromicroscopic examinations were carried out on 30 myocardial biopsies taken from 22 human donor hearts immediately after excision (prestorage) or immediately before transplantation (poststorage). All electron micrographs were independently examined by two morphologists. Eleven structures were examined in each micrograph, and each structure was scored according to the degree of injury. A good interobserver correlation was obtained in 84% of the structures scored. In the prestorage left ventricular biopsies (n = 11), approximately 20%-25% showed moderate to severe ultrastructural injury. The ultrastructural injury observed in the poststorage left ventricular biopsies (n = 15) was no different from that in the prestorage group, particularly injury to the sarcomere and mitochondria. A similar degree and pattern of injury was seen in the right ventricle (n = 4). There was no evidence that an ischemic storage period of less than 6 h increased the degree of injury seen. However, there was a higher incidence of moderate to severe injury in those hearts excised from donors initially dependent on high inotropic support.

Adolescent↗
PubMed1996

Novel actions of thyroid hormone: the role of triiodothyronine in cardiac transplantation.

In clinical heart transplantation, the heart is procured from brain dead (BD) organ donors who acutely experienced a variety of critical illnesses. In all of these conditions, a profound derangement of the thyroid profile has been observed. Although the plasma levels of thyroid stimulating hormone (TSH) remain unchanged, there is a rapid decline in free triiodothyronine (FT3) levels (p < 0.0001) as well as an elevation of reverse triiodothyronine (rT3) (p < 0.001). Following induction of experimental brain death, the heart exhibits a progressive significant hemodynamic-biochemical deterioration (reduction of cardiac contractility, depletion of high energy phosphates, glycogen, and accumulation of tissue lactate). The administration of T3 to BD animals resulted in rapid reversal of the hemodynamic and metabolic derangements. The impact of T3 therapy to unstable human brain dead organ donors has resulted in rapid hemodynamic stability allowing significant reduction of inotropic support (p < 0.001). These hearts, following cardiac transplantation, exhibited excellent hemodynamic function in the recipients. The low FT3 state has also been observed during and following open heart surgery on cardiopulmonary bypass (CPB). Therefore, at the completion of the heart transplant procedure, T3 was also administered to the recipient to prevent relapse of the hemodynamic-metabolic abnormality observed in the donor. The impact of T3 therapy to initially unstable donors allowed for rapid inotropic reduction and recovery of the heart, thus enlarging the donor organ pool and improving the outcome of the recipients following cardiac transplantation.

Animals↗
PubMed1996

Selection and management of cardiac allograft donors.

The selection of suitable donor hearts is essential for successful recipient outcome. Early allograft failure accounts for approximately 25% of deaths in heart transplantation recipients. The pool of donor organs that become available is inadequate to meet the ever increasing demand. Almost 30% of patients awaiting cardiac transplantation die before a suitable donor heart becomes available. The development of strategies aimed at expanding the donor pool are critically needed. To accomplish this goal it is important to improve donor management, prevent tissue injury following brain death, and attempt to correct donor organ dysfunction.

Animals↗
PubMed1992

Acute inotropic response of rabbit papillary muscle to triiodothyronine.

The effects of triiodothyronine (T3) on the force frequency responses of isometrically contracting rabbit papillary muscles were studied in the presence of d-glucose, pyruvate or butyrate. The stimulation frequency was varied from 0.1 to 0.5 Hz, and the maximum developed tension and its maximum (Tmx) and minimum (Tmn) time derivative were measured. T3 concentrations ranged from 0.1 to 4.0 ng/ml. The addition of T3 resulted in a substrate-dependent increase in twitch tension; with the largest increases being: d-glucose 118 +/- 7%, pyruvate 143 +/- 6%, butyrate 123 +/- 11%; Tmx:d-glucose 121 +/- 8%, pyruvate 157 +/- 5%, butyrate 138 +/- 12%, and Tmn:d-glucose 150 +/- 10%, pyruvate 159 +/- 6%, butyrate 163 +/- 14%. All three measures of contractility showed a dose-dependent increase reaching a maximum value at a T3 concentration between 1 and 2 ng/ml. These data show that T3 induces an inotropic response in rabbit papillary muscles which is manifested within, approximately 30 min, and that the greatest increase is seen in Tmn.

Animals↗
PubMed1992

Facilitated recovery of cardiac performance by triiodothyronine following a transient ischemic insult.

Reperfusion following a transient ischemic insult has been shown to result in a delayed recovery of myocardial function. A reduction in plasma triiodothyronine (T3) has been reported in these acute cardiovascular challenges. To test whether the replacement of T3 can facilitate the recovery of myocardial function following a transient regional ischemia, we investigated cardiac performance for 3 h after a 15-min, left anterior descending coronary artery occlusion in a canine model. Three groups of dogs were studied: I--control (n = 10); II--receiving T3 (0.25 micrograms/kg i.v. and 0.25 micrograms/kg/h for 3 h, n = 9), and III--receiving T3 (0.25 micrograms/kg i.v. and 0.5 micrograms/kg/h for 3 h, n = 9). Three hours following reperfusion, the T3 level in blood was significantly decreased in group I. Concomitantly, local segmental shortening was reduced from preocclusion control levels in group I (15.2 to 5.1%, p < 0.05), but recovered in both treated groups. The endsystolic elastance (Ees) and the external work (EW) efficiency (EW/PVA) in group I were depressed from preocclusion control (Ees = 95.5 +/- 0.8%; EW/PVA = 90.2 +/- 1.8%, both p < 0.05), the effective arterial elastance (Ea) and ventriculoarterial coupling (Ea/Ees) in group I were still elevated from preocclusion control (Ea = 122.5 +/- 5.1%; Ea/Ees = 128.3 +/- 5.3%, both p < 0.05). But these measures of global cardiac performance in the treated groups recovered following reperfusion, and the extent of recovery was dose dependent. These data suggest that T3 facilitates recovery of the stunned myocardium by improvement in local and global contractile function, in ventriculoarterial coupling, and in the energy efficiency.

Animals↗
PubMed1991

Triiodothyronine in the recovery of stunned myocardium in dogs.

Two groups of dogs were subjected to a 15-minute period of regional myocardial ischemia by snaring the left anterior descending coronary artery proximal to its first diagonal branch. After release of the snare, the dogs were given either placebo (group 1: n = 7) or triiodothyronine (T3) therapy (group 2: n = 6). The dose of T3 given was 0.2 microgram/kg at 30-minute intervals to a total of six doses. Plasma free T3 level fell significantly during the ischemic period in both groups and continued to fall after reperfusion in group 1. In both groups, cardiac function deteriorated significantly during the period of ischemia and rapidly returned to control level after reperfusion. After 90 minutes of reperfusion, however, deterioration of left ventricular function was observed in group 1 and was significantly worse than in group 2, in which hemodynamic function was maintained and, in fact, improved to levels superior to control. It is suggested that T3 therapy may be worthy of trial in patients in whom reperfusion of the myocardium takes place after a relatively short ischemic period (the "stunned myocardium").

Animals↗
PubMed1990

Improved cardiac allograft function following triiodothyronine therapy to both donor and recipient.

Brain death is associated with neuroendocrine changes, in particular with a significant reduction of plasma-free triiodothyronine (T3) that results in impaired aerobic metabolism. Myocardial energy stores are reduced and tissue lactate increased. Cardiac function deteriorates. Similar metabolic changes are seen in patients undergoing open-heart surgery on cardiopulmonary bypass, including those undergoing heart transplantation. Therapy with T3 leads to a reversal of these metabolic changes, resulting in improved cardiac function. One hundred and sixteen consecutive potential donors have been so treated, as have 70 of the recipients. Immediate posttransplant cardiac function was good in all but 3, and these hearts recovered to normal within a maximum of 24 hr of mechanical support. In 2 small randomized trials in patients undergoing myocardial revascularization on cardiopulmonary bypass, postoperative T3 therapy was associated with a reduced need for inotropic support and diuretic therapy in the first study and improved cardiac output in the second study.

Adenosine Triphosphate↗
PubMed1990

Experience with cardiorespiratory support devices in patients undergoing heart and heart-lung transplantation.

During the 2-year period 1987 through 1988, 124 patients were assessed for heart or heart-lung transplantation. Sixty were accepted for heart transplantation, of whom 49 received transplants. Nine required pretransplant intra-aortic balloon pump support (+/- positive-pressure ventilation) for periods ranging from 2 to 15 days (mean 5 days). One patient was supported successfully by a pneumatic biventricular assist device for 70 days pretransplant. The 30-day survival in this group of 10 critically unstable patients was 100% and the 6-month survival 90% (one death). This experience compares well with survival rates of 100% at 30 days and 92% at 6 months in the 39 patients who required no form of pretransplant circulatory support. The biventricular assist device also has been used in 2 other patients; one did not survive to transplant and the other was deemed unsuitable by virtue of cerebral injury. Extracorporeal membrane oxygenation supported 2 posttransplant patients (one heart and one heart-lung) with grossly impaired pulmonary function for periods of 5 and 2 days respectively, but both died before lung function had recovered.

Adult↗