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Biomedical subjects

H R Harter

Publications and source records attributed to H R Harter.

46 records · Page 3Linked to original sources
PubMed1977

Local blood flow characteristics of arteriovenous fistulas in the forearm for dialysis.

Local flow characteristics were studied in 21 patients with end-to-side cephalic vein to radial artery fistulas, constructed in the wrist for chronic hemodialysis. Intraoperative electromagnetic flow studies indicated a mean fistula flow of 242+/-72 milliliters per minute. Approximately two-thirds of the total fistula flow was derived from antegrade flow in the proximal part of the radial artery and one-third from retrograde flow in the distal part of the radial artery. Temporary occlusion of the distal part of the radial artery caused a 36% decrease in total fistula flow. Ten patients had an initial spasm of the radial artery which abated after 20 minutes. Calculations of a cross sectional area indicate that the size of the radial artery is more important than the size of the cephalic vein or the anastomosis in limiting total fistula flow. End of vein to side of artery anastomoses are preferred to end-to-end anastomoses because immediate retrograde flow in the distal part of the radial artery contributes significantly to total fistula flow.

Arm↗
PubMed1977

Blood flow measurements in arteriovenous dialysis fistulas.

Blood flows were measured in 75 arteriovenous dialysis fistulas (AVF) at the time of fistula construction. End cephalic vein to side of radial artery AVF had a mean flow of 242 +/- 89 ml. per minute which was similar to bovine heterograft AVF that also originated from the radial artery (291 +/- 67 ml. per minute). AVF originating from the brachial artery had flow rates twice those originating from the radial artery (599 +/- 163 vs. 251 +/- 89 ml. per minute), respectively). Flow rates were similar for straight arm (641 +/- 111 ml. per minute), curved forearm (561 +/- 187 ml. per minute), and curved thigh (592 +/- 134 ml. per minute) bovine AVF. Initial blood flow through arteriovenous dialysis fistulas is too low to cause heart failure, except in patients with previously compromised cardiac function. In such patients AVF from the radial artery theoretically would be preferred over brachial or femoral artery AVF.

Adolescent↗
PubMed1976

The relative roles of calcium, phosphorus, and parathyroid hormone in glucose- and tolbutamide-mediated insulin release.

The relative contributions of Ca++, phosphorus, and parathyroid hormone (PTH) on insulin secretion were evaluated in three groups of dogs. Dogs were studied with glucose infusions (group I) or standard intravenous glucose tolerance tests (IVGTT) (group II) before and after the development of diet-induced hypophosphatemia. Mean serum phosphorus levels for both groups fell from 4.1 to 1.1 mg/100 ml. Animals in group I demonstrated a fall in glucose disappearance rates (Kg) from 5.3+/-0.6% min to 3.5+/-0.5% after induction of hypophosphatemia (P less than 0.001). Mean insulin response was significantly greater in the hypophosphatemic animals than in controls in this group. In group II animals, mean insulin areas obtained during the IVGTT increased from 1,426+/-223 to 2,561+/-141 muU/ml/60 min after induction of hypophosphatemia, and were unaffected by Ca++ or PTH administration. Ca++ administration, but not hypophosphatemia or PTH infusion, increased significantly the mean insulin response to tolbutamide. Secondary hyperparathyroidism was induced by dietary manipulation in four dogs (group III). Mean PTH values increased from 71.4+/-2.1 to 3,012+/-372 pg/ml (P less than 0.001). Mean insulin response to an IVGTT was similar to group III animals, but increased from 1,352+/-128 to 1,894+/-360 muU/ml/60 min after the excessive dietary phosphorus was reduced for 3 mo, and plasma phosphorus fell from 3.2+/-0.1 to 2.8+/-0.3 mg/100 ml. PTH values decreased to 647+/-53 pg/ml. The insulin response to tolbutamide was comparable to that in group II animals, but increased significantly after calcium administration. Immunoreactive insulin disappearance rates were unaffected by hypophosphatemia or diet-induced secondary hyperparathyroidism. These data demonstrate that hypophosphatemia is associated with an augmented glucose-stimulated insulin release, without any effect on tolbutamide-stimulated insulin release. Hypercalcemia produces an augmented tolbutamide-stimulated insulin release with no apparent effect on glucose-stimulated insulin release. Finally, PTH does not appear to be an insulin antagonist and has no apparent effect on either glucose- or tolbutamide-stimulated insulin release in animals with dietary-induced secondary hyperparathyroidism.

Animals↗
PubMed1976

Cardiac failure and upper extremity arteriovenous dialysis fistulas. Case reports and a review of the literature.

Nine patients with high-output cardiac failure from arteriovenous forearm dialysis fistulas are reviewed, and six new cases are presented. Decreases in cardiac output with temporary fistula occlusion ranged from 0.3 to 11.0 liters/min (mean, 2.9 liters/min); fistula flow rates varied from 0.6 to 2.9 liter/min (mean, 1.5 liters/min). Surgical correction of high-flow fistulas resulted in notable improvement of cardiac failure in 13 of 14 patients. Although cardiac failure in individuals who are receiving long-term dialysis treatment is usually caused by intrinsic cardiac disease, volume overload, or anemia, forearm fistulas with large flow rates may be an important contributing factor. Correction of these large flow rates may be an important contributing factor. Correction of these large flow rates by banding or closure can substantially improve cardiac function in selected patients.

Adult↗
PubMed1976

Serum amylase determinations and amylase to creatinine clearance ratios in patients with chronic renal insufficiency.

Patients with severe chronic renal failure may have significant hyperamylasemia in the absence of clinical symptoms or signs of acute pancreatitis. Amylase to creatinine clearance (CA/CC) ratios were usually elevated in patients with chronic renal failure and were not helpful in evaluating the possibility of acute pancreatitis. The mean amylase to creatinine clearance ratio for the controls with normal renal function was 1.24 +/- 0.13. In patients with chronic renal failure, it was 3.17 +/- 0.42 (P less than 0.001). Serum amylase isoenzyme patterns revealed no difference in salivary to pancreatic isoenzyme ratios between normals (1.04 +/- 0.12) and patients with severe renal insufficiency without evidence of pancreatic disease (1.07 +/- 0.13). The isoenzymes were helpful in excluding the diagnosis of pancreatic in 1 renal failure patient whose hyperamylasemia was primarily salivary in origin and in confirming the diagnosis in another who had only a pancreatic band.

Adult↗
PubMedDate not supplied

Exercise training improves hypertension in hemodialysis patients.

6 patients with end-stage renal disease, hypertension and anemia were studied to determine the effect of endurance exercise training on their blood pressure. Initial exercise capacities were low (VO2 max = 18 +/- 2 ml/kg/min); however, their capacities increased (17 +/- 9%, p less than 0.05) after 14 +/- 5 months of training. This was associated with reductions in the antihypertensive medications in the 5 patients initially requiring them, and decreases in both predialysis systolic and diastolic blood pressures. There were significant increases in hemoglobin concentrations (7.3 +/- 0.4 to 9.8 +/- 0.9 g%) and hematocrit levels (23 +/- 2 to 30 +/- 3%) during training with no changes in body weights, interdialysis weight gains or serum albumin concentrations. 6 nonexercising dialysis patients had no changes in these same variables over the same period of time. These results suggest that endurance exercise training will reduce blood pressure and improve anemia in some hemodialysis patients.

Adult↗
PubMedDate not supplied

Axillary artery to iliac vein vascular access using an externally supported prosthetic graft. A new procedure for the recalcitrant secondary access patient.

The axillary artery-iliac vein graft using externally supported PTFE is a viable option for this difficult patient group. It is capable of functioning well for up to 12 months. Most importantly, despite numerous prior access procedures, the axillary artery and iliac vein in each case were amenable to the procedure. Critical technical points include the use of externally splinted PTFE grafts, avoidance of crossing joints, and angling of the graft in the direction of the iliac vein at that anastomosis. The lack of thrombosis or infection to date, coupled with successful dialysis in every patient, suggests that this is one more option that can be used in the difficult secondary access patient.

Adult↗
PubMedDate not supplied

Effects of prazosin in the control of blood pressure in hypertensive dialysis patients.

Twenty-two chronic hemodialysis patients with hypertension were treated with prazosin. Eight patients had volume-responsive hypertension, 11 volume-indpendent, and 3 high-renin hypertension. Blood pressure fell in all volume-responsive patients from a predialysis level of 175 +/- 5/100 +/- 3 to 148 +/- 4/75 +/- 3 mm Hg (p less than 0.001) after 3 months of therapy. Prazosin alone was effective in volume responsive patients at a dose of 5 +/- 1.0 mg daily. The blood pressure fell in volume-indpendent patients from 192 +/- 7/105 +/- 2 mm Hg predialysis to 155 +/- 6/80 +/- 3 after 3 months (p less than 0.001). Two were controlled on prazosin alone at a dose of 12 +/- 2 mg daily. Nine required 27 +/- 5 mg of prazosin daily as well as additional antihypertensive treatment. The blood pressure fell from 183 +/- 3/109 +/- 6 mm Hg predialysis to 173 +/- 17/85 +/- 3 mm Hg in high-renin patients after 3 months. One patient was controlled on 40 mg of prazosin daily. Two required 40 mg of prazosin daily as well as additional antihypertensive medication. Eleven patients described transient dizziness within the first month of therapy. One patient had recurrent syncope necessitating prazosin withdrawal; Prazosin is an effective antihypertensive agent which can be used in all types of hypertensive dialysis patients either alone or in combination with minimal side effects.

Blood Pressure↗