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Biomedical subjects

R H Peter

Publications and source records attributed to R H Peter.

At least 37 records · Page 2Linked to original sources
PubMed1983

Fracture of a polyurethane cardiac catheter in the aortic arch: a complication related to polymer aging.

An undated Cordis Ducor polyurethane coronary catheter fractured and separated in the aortic arch during a cardiac catheterization, and was removed with an intravascular retriever. The recovered specimen appeared brittle, prompting an investigation of the effects of aging on the tensile strength of 91 polyurethane catheters manufactured by Cordis and the United States Catheter and Instrument Company (USCI). Cordis catheters have stable tensile strength for five years from manufacture, but then deteriorate substantially by seven years, particularly at the bond between the catheter tip and the stainless steel-reinforced catheter body. The deterioration is associated with the microscopic appearance of deep cracks in the catheter lumen wall. USCI catheters showed a modest but significant loss of tensile strength by three years after manufacture at the catheter bond. It would seem prudent to place a three-year expiration date on USCI polyurethane catheters, similar to those already on Cordis catheters.

Adult↗
PubMed1983

Outcome in one-vessel coronary artery disease.

We analyzed the clinical outcomes in 688 patients with isolated stenosis of one major coronary artery. The survival rate among patients with disease of the right coronary artery (RCA) was higher than that among patients with left anterior descending (LAD) or left circumflex coronary artery (LCA) disease. The survival rate among patients in all three anatomic subgroups exceeded 90% at 5 years. The presence of a lesion proximal to the first septal perforator of the LAD was associated with decreased survival compared with the presence of a more distal lesion. For the entire group of one-vessel disease patients, total ischemic events (death and nonfatal infarction) occurred at similar rates regardless of the anatomic location of the lesion. Left ventricular ejection fraction was the baseline descriptor most strongly associated with survival, and the characteristics of the angina had the strongest relationship with nonfatal myocardial infarction. No differences in survival or total cardiac event rates were found with surgical or nonsurgical therapy. The relief of angina was superior with surgical therapy, although the majority of nonsurgically treated patients had significant relief of angina. The survival rate of patients with one-vessel coronary disease is excellent, and the risk of nonfatal infarction is low. Clinical strategies for the care of these patients must consider the long-term clinical course of one-vessel coronary disease.

Angina Pectoris↗
PubMed1983

Functional improvement of jeopardized myocardium following intracoronary streptokinase infusion in acute myocardial infarction.

The effect of reperfusion on regional left ventricular performance following acute myocardial infarction in man was determined. Intracoronary streptokinase was administered in 24 patients within 6 h of the onset of symptoms. 15 patients (62%) were successfully recanalized during the initial study. Mean percent radial shortening (%RS) in both the jeopardized and compensatory regions were determined using 23 radii from the centroid of diastolic and systolic angiographic silhouettes. Sequential measurements were obtained during repeat cardiac catheterization studies at 24 h in 19 patients and before discharge from the hospital (16 +/- 11 d) in 15 patients. At the time of the predischarge study, each acutely reperfused patient showed improvement in %RS in the jeopardized region (P = 0.01) with 56% returning to the normal range. Despite the uniform improvement in the contractile function of the jeopardized region in each reperfused patient, the global ejection fraction showed no improvement or a decrease at the time of the chronic study in 44%. This was due to a decrease in the compensatory wall motion in the uninvolved segments between the acute and chronic study in each case. Neither the %RS nor the ejection fraction changed significantly at the time of the chronic study in the patients who could not be acutely recanalized. These data indicate (a) significant salvage of jeopardized myocardium associated with recovery of contractile function in patients reperfused during the first 6 h of chest pain following acute myocardial infarction; (b) no improvement in regional or global left ventricular performance in patients who could not be reperfused acutely; and (c) the ejection fraction is strongly influenced by changes in the compensatory wall motion of the uninvolved segments and does not accurately reflect changes in the contractile function of the jeopardized myocardium.

Adult↗
PubMed1983

Arteriosclerotic heart disease following correction of tetralogy of Fallot.

An increasing number of people who have undergone surgical repair of tetralogy of Fallot are living long lives. Several late sequelae of corrected tetralogy of Fallot have been found, including residual ventricular septal defect, restenosis of the pulmonary outflow tract, ventricular tachycardia, and right ventricular failure from pulmonary insufficiency. A long-term survivor of corrected tetralogy of Fallot is reported with acquired coronary artery disease unrelated to the congenital anomaly or its correction as an additional cause of late morbidity in this select but growing population of patients.

Adult↗
PubMed1982

The effects of oral hydralazine on right ventricular end-diastolic pressure in patients with right ventricular failure.

Hydralazine reduces pulmonary vascular resistance in patients with primary and secondary pulmonary hypertension, but the effects on right ventricular function of a change in resistance without a reduction in pulmonary arterial pressure are not known. We evaluated the hemodynamic effects of hydralazine, 50 mg, administered orally every 6 hours for 48 hours in 14 patients with right ventricular failure and pulmonary hypertension resulting from various causes. Hydralazine reduced mean right ventricular end-diastolic pressure from 17.4 +/- 5.6 to 11.6 +/- 5.3 mm Hg (p less than 0.001) and increased cardiac output and stroke volume by more than 40%. In nine patients who had no change in mean pulmonary arterial pressure after hydralazine, total pulmonary resistance decreased from 15.9 +/- 6.0 to 10.6 +/- 4.3 (p less than 0.001) and cardiac index increased from 2.07 +/- 0.51 to 2.97 +/- 0.91 (p less than 0.005). There was a close correlation between the reductions in total pulmonary resistance and right ventricular end-diastolic pressure (r = 0.73)). These data suggest that hydralazine can increase cardiac output and reduce right ventricular end-diastolic pressure even when pulmonary arterial pressure remains unchanged.

Adult↗
PubMed1981

Hemodynamics at rest and during exercise after oral hydralazine in patients with cor pulmonale.

Oral hydralazine has been shown to be effective in decreasing pulmonary arteriolar resistance and increasing cardiac output in some patients with primary pulmonary hypertension. To determine whether a similar response could be observed in patients with chronic cor pulmonale, the hemodynamic status before and after the oral administration of hydralazine (25 mg, then 50 mg every 6 hours for 48 hours) were evaluated in 12 patients at rest and in 8 during upright exercise. After hydralazine, there was an increase in cardiac output at rest, from 4.3 to 6.3 liters/min (p < 0.001), and reductions in arteriovenous oxygen difference, from 8.1 to 6.1 volume percent (p < 0.001), mean pulmonary arterial pressure, from 52 to 44 mm Hg (p < 0.01), and pulmonary arteriolar resistance, from 11.2 to 6.2 units (p < 0.0005). Similar hemodynamic changes occurred during exercise, including an increase in pulmonary arterial saturation from 27 to 39 percent (p < 0.001) and a decrease in total pulmonary resistance from 12.7 to 8.9 units (p < 0.01). Results of pulmonary function tests performed before and after hydralazine did not change with drug administration. These findings indicate that the lung vascular bed in some patients with cor pulmonale is capable of responding to hydralazine with a reduction in pulmonary resistance and an increase in cardiac output both at rest and during exercise.

Adult↗
PubMed1980

Oral hydralazine therapy for primary pulmonary hypertension.

To evaluate the hemodynamic effects of hydralazine in four patients with primary pulmonary hypertension, we catheterized the right side of the heart before and 48 hours after starting therapy with oral hydralazine, 50 mg every six hours. Data were obtained at rest in four patients and also during exercise in three. After hydralazine, total pulmonary resistance at rest fell from 17.5 to 7.7 U, and pulmonary arteriolar resistance from 15.6 to 7.1 U; cardiac output increased from 3.8 to 7.1 liters per minute, and the arteriovenous oxygen difference narrowed from 7.8 to 5.4 ml per deciliter. Mean pulmonary and systemic arterial pressures were unchanged. Hydralazine also caused total pulmonary resistance during exercise to fall from 15.7 to 10.2 U, and cardiac output to rise from 4.7 to 7.0 liters per minute. Treatment was continued, and on repeat catheterizations three to six months later the hemodynamic effects persisted. These data suggest that hydralazine can reduce pulmonary resistance in some patients with idiopathic pulmonary hypertension.

Administration, Oral↗
PubMed1980

Right ventricular obstruction secondary to intracardiac metastatic osteosarcoma.

A 30-year-old female with a history of surgically treated osteosarcoma 2 years prior to admission presented with progressive dyspnea and cyanosis. Physical examination was otherwise negative. Cardiac catheterization demonstrated a right ventricular mass lesion. At surgery, a metastatic osteosarcoma filling the entire right ventricle and extending from the pulmonary valve across the tricuspid valve and into the right atrial cavity was partially excised. Despite marked improvement postoperatively, she did 33 d after surgery. Postmortem findings were unusual in that the heart represented the sole site of metastasis. The diagnostic approach to cardiac symptoms from malignancy is discussed in relation to this patient.

Adult↗
PubMed1980

The diagnostic and prognostic significance of coronary artery calcification. A report of 800 cases.

The significance of coronary artery calcification was assessed in 800 patients who underwent cardiac fluoroscopy and selective coronary cineangiography. Calcification was shown by fluoroscopy in 250, of whom 236 (94%) had greater than or equal to 75% stenosis of one or more major coronary arteries at angiography. Among patients with significant coronary artery disease, 40% (236/585) had calcification. Patients with calcification demonstrated poorer survival at all follow-up intervals (from six months to five years); the five-year survival rate was 87% for patients without calcification, compared to 58% for those with calcification. The prognostic significance of coronary artery calcification appears to be independent of information obtained by cardiac catheterization and angiocardiography.

Calcinosis↗
PubMed1980

A new approach to clinical decision-making in coronary artery disease: observations on subsets within the Duke University Data Bank.

In summary, the Duke University Coronary Artery Disease Data Bank contains over 4,000 patients. It plays an important role in clinical decision-making in the management of individual patients. Current research projects involve the elucidation of natural history and the development of multivariable statistical methods for analyzing large numbers of baseline characteristics in a large number of patients. With these techniques, the data bank will continue to be a powerful tool in rationally examining the benefits of present and future therapeutic interventions in the management of patients with coronary artery disease.

Coronary Disease↗
PubMed1980

Rest and exercise hemodynamic effects of oral hydralazine in patients with coronary artery disease and left ventricular dysfunction.

To determine the hemodynamic effects of afterload reduction at rest and during upright exercise in patients with coronary artery disease and left ventricular dysfunction, 12 patients were studied before and after taking 50-75 mg of oral hydralazine every 6 hours for 48 hours. Oxygen consumption and heart rate were unchanged from control both at rest and during two work loads on a bicycle ergometer. Cardiac output was significantly increased at rest and during both workloads. The arteriovenous oxygen difference was significantly reduced at rest and during exercise. Pulmonary capillary wedge pressure was also significantly lower at rest and during exercise. Systemic vascular resistance was reduced at rest, and exercise-induced vasodilation was augmented by the administration of hydralazine. Left ventricular end-diastolic volume and ejection fraction assessed by radionuclide angiocardiography were not significantly changed at rest or during exercise after hydralazine. Seven of the 12 patients have maintained clinical improvement during a follow-up of 6-12 months. Hemodynamic improvement provided by oral hydralazine at rest is maintained during moderate exertion in patients with coronary artery disease and left ventricular dysfunction. In selected patients, chronic afterload reduction with oral hydralazine may result in increased cardiac reserve, decreased pulmonary congestion or decreased myocardial oxygen demands, thereby improving or abolishing resting or exertional dyspnea or angina.

Aged↗
PubMed1979

Left bundle branch block: angiographic segmental wall motion abnormalities.

Ventricular wall motion as studied with contrast ventriculography has been judged normal in the few previously reported cases of patients with left bundle branch block who have neither coronary artery disease nor diffuse cardiomyopathy. However, recent echocardiographic studies have demonstrated a high frequency of segmental asynergy of the septal wall in such patients. In this study left ventricular wall motion was analyzed in 15 patients with left bundle branch block and without significant coronary artery disease or diffuse cardiomyopathy. Biplane cineangiograms from these patients were compared with those from 100 consecutive patients with normal intraventricular conduction and without coronary artery disease or cardiomyopathy using two techniques: qualitative visual inspection and a computer-assisted quantitative method. By qualitative review, 6 of 15 patients with left bundle branch block had regional akinesia or dyskinesia as compared with none of 100 patients with normal intraventricular conduction (chi square = 42.3; P less than 0.001). By quantitative review, 10 of 12 patients with left bundle branch block had abnormal wall motion along at least one hemiaxis. It is concluded that angiographic regional wall motion abnormalities are common in patients with left bundle branch block, even in the absence of coronary artery disease or diffuse cardiomyopathy. The abnormalities may result from the abnormal sequence of ventricular activation rather than from myocardial fibrosis.

Adult↗
PubMed1978

The role of the exercise test in the evaluation of patients for ischemic heart disease.

A cohort of 1472 patients who underwent both exercise stress testing and coronary angiography within six weeks was examined. The data indicated that a combination of exercise parameters is both diagnostically and prognostically important. Almost all patients (greater than 97%) who had positive exercise tests at Stage I or Stage II had significant coronary artery disease. More than half of these (greater than 60%) had three vessel disease and over 25% had significant narrowing (greater than 50%) of the left main coronary artery. Patients who achieved Stage IV or greater exercise durations with either negative or indeterminate ST-segment response had less than a 15% prevalence of three vessel disease and less than a 1% prevalence of left main coronary artery disease. A low risk subgroup (75% of all non-operated patients) was identified with a twelve month survival greater than 99%. A high risk subgroup (11% of all nonoperated patients) was identified with a twelve month survival of less than 85%. The exercise test is a noninvasive, reproducible method to assess the presence and extent of anatomic disease and the prognosis when significant disease has been defined. It should be used in conjunction with other noninvasive tests to determine optimal management in patients evaluated for ischemic heart disease.

Angiocardiography↗
PubMed1976

Aortocoronary bypass surgery: Correlation of angiographic symptomatic and functional improvement at 1 year.

Angiographic changes in the coronary circulation were evaluated in 60 patients 1 year after aortocoronary bypass surgery, and their relation to the postoperative clinical status was examined. Of 124 grafts implanted, 26 were closed, 7 stenotic and 91 (74 percent) patent at 1 year. Progression of occlusive disease occurred in 21 of 57 (37 percent) nongrafted and 78 of 123 (63 percent) grafted vessels. On the basis of location and severity of progression, significant lesions bypassed and patency of grafts, postoperative coronary perfusion was considered optimal in 16 patients (Group I), better in 24 (Group III). Complete freedom from chest pain or lessening of pain (improvement by two New York Heart Association functional classes) occurred in 88 and 79 percent of patients in Group III. Positive preoperative treadmill stress tests became negative after surgery in five of six patients in Group I, five of eight in Grojp II and three of eight in Group III. This study demonstrates that when progression of disease, graft patency and extent of revasculariztion are considered in combination, the postoperative angiographic status of the coronary circulation correlates well with clinical improvement at 1 year. These findings support the hypothesis that improved blood supply to ischemic myocardium is a major factor contributing to relief of angina pectoris after saphenous vein bypass surgery.

Coronary Artery Bypass↗
PubMed1976

The hemodynamic simulation of mitral regurgitation in ventricular septal defect after myocardial infarction.

The development of a ventricular septal defect (VSD) following myocardial infarction is an uncommon complication which clinically can be confused with mitral insufficiency due to infarction of a papillary muscle. The clinical and hemodynamic records of six patients with documented acute VSD secondary to myocardial infarction were analyzed to determine which descriptors would be of value in clinically separating these two entities. All six of our patients had a right heart catheterization showing an oxygen step-up consistent with a VSD, and five had a large pulmonary wedge V wave suggesting concomitant mitral insufficiency. The echocardiogram showed only nonspecific chamber enlargement. Since these patients were being considered for open heart surgery to close the VSD, left and right cardiac catheterization including selective coronary arteriography was done. Despite large V waves being present in the pulmonary wedge and/or left atrial pressure tracing in five of the six patients, no mitral insufficiency was present on the left ventricular cineangiograms. It is concluded that a large pulmonary wedge and/or left atrial V wave does not necessarily indicate mitral insufficiency. Since both a VSD and mitral insufficiency are surgically correctable, patients who develop new holosystolic murmurs following myocardial infarction should have complete right and left heart catheterizations with LV angiography for accurate diagnosis if surgical correction of the lesion is contemplated.

Acute Disease↗