Jeanne M. Riddle

Spontaneous Degeneration of Porcine Bioprosthetic Valves

From October, 1971, to October, 1979, 490 patients with 560 porcine bioprosthetic valves were discharged from the hospital. During these 8 years, 23 valves were removed because of failure due to spontaneous degeneration. Bioprosthetic valve survival without degeneration was at 4 years, 98.9% +/- 86 (standard error); at 5 years, 96.4% +/- 1.3; at 6 years, 90.8% +/- 2.4; and at 7 years, 84.2% +/- 3.7. There was no difference in degeneration observed with regard to sex, valve position, or whether the valves were rinsed with antibiotics prior to implantation. There was an increase in degeneration in patients 35 years old and younger compared with those more than 35 years old (p = 0.0001). Valve failure was gradual, and valve changes were noted by echocardiogram and phonocardiogram prior to actual failure. Specific factors leading to degeneration require further investigation.

Effects of chronic smoking on platelet function

Platelet function was investigated in 20 healthy cigarette smokers and 23 nonsmokers. Cigarette consumption was 1.4 +/- 0.5 packs/day (mean +/- SD) and the duration of smoking was 19 +/- 12 years. Platelet surface activation in vitro, aggregation in vivo and in vitro, as well as the release of platelet-specific proteins in vivo were evaluated. The mean number of platelet aggregates counted on an activating surface (Formvar film) was higher in smokers (80 +/- 59) than in nonsmokers (43 +/- 27) (P less than .01), indicating enhanced activity following exposure to an activating surface. Smokers who were 50 years of age or older showed an enhanced platelet aggregation following an in vitro stimulation in comparison to younger smokers (105 +/- 54 vs 54 +/- 55 aggregates) (P less than .05). Those who smoked 20 years or more also showed enhanced aggregation in comparison to those who smoked less than 20 years (112 +/- 60 vs 53 +/- 45 aggregates) (P = .02). Circulating platelets showed no significant difference among smokers and nonsmokers in the following tests: platelet aggregate ratio (0.67 +/- 0.30 vs 0.86 +/- 0.76), platelet count per mm3, (310,000 +/- 82,000 vs 278,000 +/- 78,000/mm3), levels of platelet factor 4 (9.8 +/- 5.2 vs 9.4 +/- 5.3 ng/ml), and plasma concentrations of beta-thromboglobulin (53.9 +/- 23.5 vs 49.1 +/- 25.5 ng/ml). The data suggest that chronic smoking primes platelets, causing them to aggregate more readily when exposed to an activating stimulus in vitro.

Functional and Ultrastructural Abnormalities of Platelets in Ehlers-Danlos Syndrome

Excerpt A bleeding tendency is one of the salient features of Ehlers-Danlos syndrome. An altered vascular and supportive tissue structure has previously been considered to be the cause. Observation...

Platelet ultrastructure and secretion in acute ischemic stroke.

We used transmission electron microscopy to count the organelles (dense bodies, alpha granules, and mitochondria) contained within platelets from 11 acute ischemic stroke patients and 12 healthy controls. We randomly selected for evaluation 25 platelet profiles in ultrathin sections cut from three separate blocks. Compared with those from controls, platelets from stroke patients contained significantly fewer alpha granules (p less than 0.001) and mitochondria (p less than 0.02) and showed a trend toward fewer dense bodies. Supportive of our previous studies, the amount of adenosine triphosphate secreted following stimulation by collagen also tended to be greater in platelets from stroke patients. These observations support the presence of increased platelet secretion associated with acute cerebral infarction and raise the possibility that platelet secretion may be of separate importance to the mechanical occlusion of blood vessels by platelet aggregates in the pathogenesis of cerebral infarction.

Relation of Calcification to Torn Leaflets of Spontaneously Degenerated Porcine Bioprosthetic Valves

The gross appearance of 54 spontaneously degenerated porcine bioprosthetic valves was evaluated to determine the relation of calcium deposition to cusp disruption. Tears or perforations were shown in 89% (48) of the degenerated valves. The most common site of tears or perforations was near the commissural attachment (60% of all tears). Grossly visible deposits of calcium salts that ruptured to the surface of the cusps or caused changes in the topography were observed in 70% (38) of the 54 valves. Calcification was adjacent to tears or perforations in 56% (27) of the 48 valves with torn cusps. Among the valves that showed calcification, the deposits of calcium salts were adjacent to tears or perforations in 71% (27 of 38). The location of deposits of calcium did not relate to the age or sex of the patient or to the position of the valve, but valves with calcium were inserted longer than valves with no calcium (87 +/- 4 versus 58 +/- 7 months; p less than 0.001). The outflow surfaces showed more calcification than the inflow surfaces, irrespective of whether the valves were in the aortic or mitral position. Among the 38 valves with calcification, 92% (35) showed calcification at the commissural attachments, 53% (20) showed calcification in the body of 1 or more cusps, 11% (4) near the base, and 8% (3) near the free edge. In conclusion, most patients with spontaneous porcine valve degeneration showed calcification. The calcification was associated with tears or perforations of the cusps in 50% of all degenerated valves, in 56% of valves with torn cusps, and in 71% of valves that showed gross calcification.

A Modified Technique for Small-Bowel Transplantation in the Rat

The rat model for small-bowel transplantation is becoming increasingly popular. The currently accepted microsurgical technique, however, is complicated by extensive dissection in the donor rat vascular system requiring a great deal of manipulation of the vessels themselves, with consequent complications of thrombosis and vascular injury. We describe a procedure for small-bowel transplantation in the rat that simplifies the currently accepted technique. The peripheral portion of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) is used as the vascular pedicle of the segment of bowel to be transplanted rather than the SMA with an aortic cuff and the portal vein as previously described. The SMA and SMV are anastomosed to recipient aorta and inferior vena cava respectively. The bowel extremities are exteriorized, thus leaving access to the lumen for further studies. All anastomoses are performed with interrupted 10-0 nylon sutures. The procedure was performed in 11 animals. Good revascularization of the transplant was defined as immediate filling of the transplant vasculature with normal (pink) appearing bowel. Eight of the recipients had excellent revascularization. Venous occlusion was the cause of early failure in the remaining three animals. All animals were killed, autopsies performed, and the anastomoses examined. The longest survivors were killed at 7 months. Biopsies were obtained immediately and at daily intervals. Early ultrastructural changes of rejection in the transplanted bowel were studied by electron microscopy. Changes in the microvasculature were seen early after transplantation. Immunologic changes were apparent only later in the course of rejection. We conclude that this technique is successful in achieving functional small-bowel transplants in the rat.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of platelet reactivity in patients with valvular heart disease

Transmission electron microscopy with a standardized in vitro method was used to evaluate the degree of blood platelet reactivity in 72 normal subjects and 72 patients with valvular heart disease. Among the patients with abnormal natural heart valves, 51 had either aortic insufficiency or aortic stenosis, and 21 patients showed either mitral insufficiency or mitral stenosis. For normal subjects, the platelet differential counts were dominated by the dendritic type platelet, and only a few platelets showed cytoplasmic spreading between adjacent pseudopodia (spread type). A hyperactive response was defined as greater than 20% of the spread type platelet or more than 93 aggregates per 100 single platelets counted, or both. Only 6 (8%) of the 72 normal subjects showed hyperactive platelets. In contrast, 45 (62%) of the 72 patients with valvular heart disease had hyperactive platelets (p less than 0.01). For patients with abnormal valves, the mean percent of the spread type platelet was 35% with a mean value of 105 platelet aggregates. The increased level of platelet reactivity was independent of both the position of the valve (aortic versus mitral) and its functional status (insufficient versus stenotic). Disturbed flow and the exposure of subendothelial thrombus-producing materials are features associated with abnormal heart valves. These factors, which usually occur in combination, may explain the hyperactive platelet response found in these patients.

Gastric Bypass in Patients Weighing More Than 500 Ib: technical innovations for the ‘ultraobese’

The Roux-en-Y gastric bypass (RYGB) is a demanding operation. It is more difficult to perform than most vertical pouch gastroplasties and is associated with a greater number of life-threatening complications. This study addresses the technical problems facing the bariatric surgeon when the RYGB is performed on patients weighing more than 500 Ib. It represents an 8-year operative experience with 2050 morbidly obese patients, 23 (1.1%) of whom were classified as ‘ultraobese’. Specific steps of the RYGB have been analysed and refined. Using the technical innovations described, the bariatric surgeon can perform the RYGB in the ultraobese patient with a reasonable degree of morbidity and mortality. Without the potential for safe surgical intervention, the prognosis for this group of patients is grim at best.

Platelet activation and analysis of organelles in migraineurs.

SYNOPSIS

Platelet adherence to bioprosthetic cardiac valves

Tissue from porcine aortic bioprosthetic valves (Hancock) and bovine pericardial valves (Ionescu-Shiley) were incubated with platelets tagged with chromium-51. There was a significantly decreased platelet-collagen adhesion reaction in both porcine and bovine glutaraldehyde-treated valves compared with reactions in fresh porcine aortic valve and fresh bovine pericardium (p less than 0.001). There was no significant difference in the platelet-collagen reaction between porcine aortic valve and bovine pericardium, whether treated with glutaraldehyde or in the fresh state (p greater than 0.05). The addition of aspirin did not significantly decrease the platelet-collagen reaction on glutaraldehyde-treated or fresh valves (p greater than 0.05). Rinsing fresh valves in plasma appeared to offer more protection against platelet adhesion than rinsing them in saline solution (p less than 0.01). It is concluded that there is no difference in platelet adherence to porcine aortic valve or bovine pericardium and that glutaraldehyde, and perhaps plasma, offers a protective effect against platelet adhesion.