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Biomedical subjects

C B Mullins

Publications and source records attributed to C B Mullins.

14 recordsLinked to original sources
PubMed1979

A comparison of mathematical models for estimating right ventricular volumes in animals and man.

Volume of 19 right ventricular canine casts and 11 right ventricular human casts were obtained by water displacement and compared to three different mathematical models for estimating right ventricular volumes by biplane cineangiography. In the canine studies, significant linear correlation coefficients were obtained using the longest measured length method (r = 0.92), the triangular modification of Simpson's rule (r = 0.93), and the elliptical modification of Simpson's rule (r = 0.93). The human studies resulted in similar significant correlation coefficients of 0.96, 0.97, and 0.97, respectively. Although the highest correlation with the lowest standard error of estimate was obtained using the triangular model, all three mathematical models produced volume estimations that feel within acceptabe biological limits of accuracy.

Animals↗
PubMed1977

Critique of coronary artery bypass surgery.

Patients with single-vessel disease, with normal or mildly abnormal ventricular function (EF greater than 40%), have a good prognosis both for natural survival and long-range symptomatic improvement; therefore medical therapy is strongly recommended. Surgery is considered only if symptoms persist after aggressive medical therapy. It is possible that single-vessel left anterior descending disease is a special variant of this group, and surgery may, with further reports, show an increased survival. However, no adequately designed study has yet suggested this, and it is currently our opinion that patients with single-vessel disease do not have an improved survival following surgery. It is not clear whether surgery improves survival in patients with multivessel disease and normal or mildly abnormal ventricular function (EF greater than 40%). Consequently, cardiologists are divided as to whether to advise surgery in these patients solely for survival. Currently, it is our opinion that these patients should have surgery only for improvement of symptoms after failure of medical therapy. In left main coronary disease the evidence favoring improved survival after surgery has convinced most cardiologists, including ourselves, to recommend surgery. Patients with poor ventricular function (EF less than 30%) secondary to coronary artery disease often have congestive heart failure and not angina as their chief symptom. Surgery is usually not advisable for these patients, because of the increased operative mortality and lack of improvement in ventricular function. Patients with poor ventricular function with angina are not usually significantly improved by surgery. In patients with moderately abnormal ventricular function (EF = 30-40%), relief of angina is frequently obtained, but with some added surgical risk. We recommend surgery in these patients after aggressive medical therapy has failed. Patients with unstable angina are initially medically stabilized, after which they are generally managed as stable angina. Patients with persistence of pain at rest in spite of vigorous medical therapy are usually managed by early catheterization and surgery.

Age Factors↗
PubMed1977

Cardiovascular function during early recovery from acute myocardial infarction.

Fifty patients with acute myocardial infarction were studied serially to evaluate the extent and nature of functional cardiovascular impairment and the time course of recovery. Reinfarction or death occurred in six patients. Peak workload during bicycle exercise in a subgroup of 25 patients with maximal initial test and complete follow-up increased from 334 to 409 kpm/min (P less than 0.01) bwtween three and six weeks. There was further significant (P less than 0.01) improvement between three and six months from 438 to 488 kpm/min. The incidence of ischemia at a constant workload decreased between three and six weeks without any significant changes in heart rate or blood pressure. Mean cardiac output during exercise at three months was 6.5 and at six months 7.8 L/min (P less than 0.05). Corresponding values for stroke volume were 61 and 72 ml (P less than 0.05). The data suggest that in clinically stable patients there is an early improvement of the relation between myocardial oxygen supply and demand and a late improvement of functional capacity associated with increased stroke volume and cardiac output.

Acute Disease↗
PubMed1977

Left ventricular function during lower body negative pressure.

The purpose of this study was to characterize the response of the human left ventricle to lower body negative pressure (LBNP) and to delineate the relation between left ventricular function and hemodynamic response. Ventricular function curves relating stroke volume to end-diastolic volum were obtained in 12 normal men. Volume data were derived from echocardiographic measurements of left ventricular end-systolic and end-diastolic diameters at rest and during LBNP at -40 mm Hg. End-diastolic volume decreased by 19% (p less than 0.01) and stroke volume by 22% (p less than 0.05). There were no significant changes in heart rate, arterial blood pressure, or end-systolic volume. Thus, moderate levels of LBNP significantly reduce preload and stroke volume, i.e. produce a Starling effect, without affecting contractile state. The absence of significant changes in heart rate and arterial blood pressure in the presence of a significant reduction in stroke volume is consistent with an increase in systemic peripheral resistance medicated by low-pressure baroreceptors.

Adult↗
PubMed1976

Permanent pacing in patients with transient trifascicular block during acute myocardial infarction.

Patients with acute myocardial infarction and transient complete atrioventricular (A-V) block in association with right bundle branch block and left anterior hemiblock have a high incidence rate of late sudden death presumably due to recurrent A-V block. Over a 5 year period, 18 patients demonstrated right bundle branch block and left anterior hemiblock and had transient complete block during an acute myocardial infarction and survived to hospital discharge. Of six patients who did not have permanent pacing, five died suddenly (one was lost to follow-up) with a mean survival time of 2.4 months after hospital discharge. Twelve subsequent patients received permanent demand pacemakers and had a significantly improved prognosis with a mean survival time of 18 months (P less than 0.001). Six patients were still alive at an average follow-up time of 20 months. Prophylactic permanent pacing significantly improves the prognosis after acute myocardial infarction in this select subgroup of patients.

Acute Disease↗
PubMed1976

Incidence of arrhythmias induced by isometric and dynamic exercise.

The incidence of arrhythmias during isometric sustained handgrip exercise and during dynamic graded bicycle exercise was compared in a group of 45 patients with various forms of heart disease on no antiarrhythmic therapy. Atrial arrhythmias were equally common during handgrip and bicycle exercise but ventricular arrhythmias were more frequent during handgrip exercise. Of the 45 patients, 38 per cent developed ventricular arrhythmias during isometric exercise, with ventricular tachycardia occurring in 15 per cent. During dynamic exercise 22 per cent of the 45 patients developed ventricular arrhythmias, with ventricular tachycardia occurring in 2 per cent. Patients with coronary artery disease and/or depressed left ventricular function developed twice the incidence of ventricular arrhythmias with isometric than with dynamic exercise. Thus, isometric exercise testing is of more value than dynamic exercise testing in unmasking latent ventricular arrhythmias in patients with heart disease.

Adult↗
PubMed1976

Prognosis of patients permanently paced for sick sinus syndrome.

In 39 patients (mean age, 66 years) treated for sick sinus syndrome (SSS) with pacemaker insertion, the long-term prognosis was studied. Fifteen patients (42%) died during the follow-up period of 6 to 59 months (mean, 25 months). Three patients were unavailable for follow-up. Eleven of the 15 deaths (73%) were cardiac-related, yet none could be associated with either an arrhythmia or pacemaker failure. Symptoms recurred or persisted after pacemaker insertion in 14 patients (mean age, 71 years), nine of whom died (31 deaths per 100 patient follow-up years). Twenty-two patients (mean age, 63 years) were asymptomatic after pacer insertion, six of whom died (11 deaths per 100 patient follow-up years). These follow-up results demonstrate a poor long-term prognosis in patients with SSS and persistent symptoms following permanent pacing.

Aged↗
PubMed1975

Variant angina pectoris: a clinical and coronary arteriographic spectrum.

The clinical course and coronary arteriographic findings in eight patients with Prinzmetal's variant angina pectoris are reviewed and contrasted to previously reported cases. In six patients with S-T-elevation inferiorly, three had normal coronary arteriograms, one had complete right coronary artery occlusion, one had diffuse triple-vessel disease, and one did not undergo coronary arteriography. In two patients with S-T-elevation anteriorly, severe stenosis of the anterior descending coronary artery was present. Medical treatment in four patients and surgical revascularization of the anterior descending coronary artery in two patients were both accompanied by marked symptomatic improvement. Spontaneous loss of angina occurred in two patients. During 17 months' mean follow-up, seven patients have remained free of angina and one died suddenly. Variant angina pectoris may be accompanied by a variety of coronary arteriographic findings and the prognosis appears more favorable than previously reported.

Adult↗
PubMed1975

Intraaortic balloon counterpulsation in patients in cardiogenic shock, medically refractory left ventricular failure and/or recurrent ventricular tachycardia.

Of the 27 patients described, 23 were in cardiogenic shock, 2 had severe left ventricular failure, and 2 had medically refractory ventricular tachycardia. Utilizing intraaortic counterpulsation, adequate systemic blood pressure was initially restored in 19 patients. Nine of these were subsequently weaned from circulatory assistance, but only three were discharged from the hospital and are currently alive. The remaining 10 patients who derived initial benefit from circulatory assistance were balloon-dependent in that they could not be weaned from circulatory assistance. Eight of these patients subsequently underwent cardiac catheterization; four had inoperable disease. The remaining four patients underwent surgery for either resection of the area of infarction and/or for myocardial revascularization; only one survived to subsequently leave the hospital. Ventricular volumes were abnormal and ejection fractions were below 30 per cent in all the patients in cardiogenic shock except one who underwent cardiac catheterization and ultimately died. Ejection fractions were greater than 30 per cent in the two patients with cardiogenic shock who were weaned from balloon support and survived to leave the hospital without surgery. Both of these patients had inferior myocardial infarction. The data obtained from this experience suggest that intraaortic counterpulsation is a very useful adjunct to currently existing medical measures to treat both cardiogenic shock and medically refractory left ventricular failure but that most patients have such extensive disease that they can neither be weaned from balloon support nor undergo successful infarctectomy or myocardial revascularization.

Adult↗
PubMed1975

Skeletal muscle metabolites in patients with cardiogenic shock or severe congestive heart failure.

Skeletal muscle metabolite concentrations were determined in 19 patients in either cardiogenic shock or severe left ventricular failure by obtaining a needle biopsy specimen of lateral thigh muscle. Evidence of anaerobic skeletal muscle metabolism was found in both patient groups with the greatest lactate accumulation and most severe high-energy phosphate depletion present in the patients in cardiogenic shock. The skeletal muscle lactate accumulation was most pronounced in the patients that died. Blood lactate values did not absolutely predict skeletal muscle lactate concentrations in those patients in whom skeletal muscle lactate concentrations were the highest. The patients in cardiogenic shock and severe left ventricular failure who survived demonstrated a reduction in skeletal muscle lactate levels and a restoration of high-energy phosphates over several days which correlated with clinical and hemodynamic improvement.

Adenosine Triphosphate↗