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Biomedical subjects

P F Cohn

Publications and source records attributed to P F Cohn.

At least 145 records · Page 8Linked to original sources
PubMed1977

A new, noninvasive technique for inducing post-extrasystolic potentiation during echocardiography.

Left ventricular function was evaluated in 34 patients with the echocardiogram, and an external mechanical cardiac stimulator was used to induce a ventricular premature contraction (VPC) noninvasively. Extent of post-extrasystolic potentiation (PESP) was determined by comparing systolic dimensional shortening and ejection fraction of the sinus beat preceding the VPC to that of the potentiated beat which followed it. Using this technique, a VPC could be introduced into the cardiac cycle of 30 of the 34 patients, six of whom were free of obvious cardiac disease and 24 of whom had valvular, coronary or myopathic heart disease. The only complication observed was mild breast ecchymosis in a female patient. Systolic dimensional shortening and ejection fraction increased from control values by an average of 21% and 17% respectively, with a range of 0-100%. The degree of PESP was very reproducible in repeat studies and when the same patients were subsequently evaluated during a spontaneously occurring or catheter-induced VPC. The technique can safely and reliably induce post-extrasystolic potentiation during echocardiography and is a potentially important adjunct to the noninvasive evaluation of left ventricular function.

Adult↗
PubMed1976

Clinical significance of coronary arterial ectasia.

In a study group of 2,457 consecutive patients undergoing cardiac catheterization, 30 patients had coronary arterial ectasia, an irregular dilatation of major vessels up to seven times the diameter of branch vessels. The frequency of hypertension, abnormal electrocardiogram and history of myocardial infarction was greater than that in a control group with obstructive coronary artery disease. Patients with ectasia did not differ from patients with obstructive disease in sex, age, prevalence of angina or presence of metabolic abnormalities. Six deaths occurred in the group with ectasia during a mean follow-up period of 24 months (annual rate of 15 percent). Extensive destruction of the musculoelastic elements was evident, resulting in marked attenuation of the vessel wall. The short-term prognosis in this group is the same as in medically treated patients with three vessel obstructive coronary artery disease.

Adolescent↗
PubMed1976

Regional myocardial blood flow during hyperemia induced by contrast agent in patients with coronary artery disease.

Regional myocardial specific blood flow (regional specific flow) was measured at rest and during contrast hyperemia after the intracoronary injection of xenon-133. The changes in regional specific flow were transient, resulting in some compromise in one of the underlying restraints of the inert gas washout method, namely, the presence of a steady state. Therefore, to determine the clinical utility of this technique, regional specific flow values obtained with this method were correlated with the presence and severity of coronary artery disease as assessed from the coronary arteriogram and left ventriculogram. Regional specific flow during contrast hyperemia was 186+/- 11 (mean +/- 1 standard error of the mean) ml/min per 100 g in control patients and 115+/-5 in patients with coronary artery disease. There was an inverse relation between regional specific flow during contrast hyperemia and the percent coronary stenosis when the stenosis was 40 percent or greater (r = 0.70, P less than 0.001). Regional specific flow was significantly less in patients with asynergy (77 +/- 10 ml/min per 100 g) than in patients with normal ventricular function (105 +/- 5) distal to coronary stenoses of greater than 75 percent. Thus regional specific flow measured during contrast hyperemia using the xenon washout technique and the Anger camera differentiated patients with normal coronary arteriograms from those with coronary artery disease. With this technique, good correlation was shown between regional specific flow and the percent coronary stenosis and presence of ventricular wall abnormalities. The information obtained with this method may provide prognostic information concerning suitability for surgical intervention.

Angiocardiography↗
PubMed1976

Comparison of selective left ventriculograms with levophase ("forward") ventriculograms in patients with coronary artery disease.

In order to compare levophase ("forward") ventriculograms to standard (selective) LV cineangiography, 10 patients with coronary artery disease were studied by (1) selective injection of contrast medium into the LV cavity followed by (2) injection into the right ventricle and filming the levophase. Biplane cineangiograms were used to calculate the end-diastolic volume index (EDVI), end-systolic volume index (ESVI), stroke volume index (SVI), and ejection fraction (EF). Values for the two respective techniques were then compared. Not only were correlation coefficients for the two methods low, but there was also a statistically significant difference between the two SVI (66 +/- 26 ml. for selective and 53 +/- 25 ml. for levophase injection; p less than 0.02) and the two EF (67 +/- 7 per cent for selective and 52 +/- 12 per cent for levophase injection; p less than 0.01). Levophase cineangiograms therefore significantly underestimate the LV ejection fraction when compared to standard (selective) LV cineangiography. These differences must be considered when evaluating greatly divergent interinstitutional survival rates for patients with low EF who undergo coronary artery bypass surgery, and when selecting candidates for bypass surgery on the basis of the angiographic data.

Adult↗
PubMed1976

Angiographic abnormalities associated with alterations in regional myocardial blood flow in coronary artery disease.

To evaluate the association between alterations in myocardial blood flow and angiographic findings, myocardial blood flow was compared in 26 patients with asymergy, 15 patients with a similar extent of coronary artery disease but without asynergy, and 10 patients without coronary artery disease or obvious myocardial or valvular disease. Myocardial blood flow was measured at rest with an Anger camera and PDP-11/20 computer after the intracoronary injection of 133xenon. In comparison with the normal subjects, whole heart blood flow was significantly reduced in patients with asynergy. In addition, myocardial blood flow in regions of anteroapical asynergy was reduced (85-7 +/- 7-0 ml/min per 100 g3 in controls to 65-4 +/- 4-5, P less than 0-05) and a similar reduction was noted in regions of posterolateral asymergy (91-5 +/- 8-8 in controls to 66-8 +/- 5-0, P less than 0-05). In general, regional myocardial blood flow was reduced distal to left anterior descending or left circumflex stenosis of less than 50 per cent, with a trend toward further reduction distal to less than 75 per cent stenosis. In these same patients, the presence of anteroapical or posterolateral asynergy resulted in a similar trend to even greater reduction of flow. The effect of collaterals was variable: 7 of 8 patients without asynergy but with less than 75 per cent left anterior descending stenosis and collateral circulation to the lower left anterior descending quadrant had minimally reduced flows. However, in the 17 patients with anteroapical asynergy, regional myocardial blood flow was very similar in the 9 patients with collaterals compared with the 8 patients without them. This study suggests that the degree of coronary artery stenosis and presence of asynergy are both important in evaluating alterations in myocardial blood flow in coronary artery disease, while the role of collaterals remains uncertain.

Adult↗
PubMed1976

Serum lipid levels in angiographically defined coronary artery disease.

To evaluate the association between serum cholesterol and triglyceride levels and angiographically determined coronary artery disease, two selected groups of 100 patients each were compared. The coronary artery disease group had significantly higher serum levels of both cholesterol and triglyceride. However, several types of analyses based on the quartile distribution of serum levels of cholesterol and triglyceride showed that the serum cholesterol level was more significantly associated with coronary artery disease than was the triglyceride level. This was especially true in relation to multivessel disease, the most severe form of coronary artery disease, and most marked in men. Association with coronary artery disease appeared to be continuous, rather than being related to any critical serum level, thus re-emphasizing the need to distinguish between desirable and average levels of serum cholesterol in countries with a high dietary intake of saturated fat.

Adult↗
PubMed1976

Use of the augmented ejection fraction to select patients with left ventricular dysfunction for coronary revascularization.

Thirty-three patients with angina (31 men and 2 women, age 33 to 68 years, 52), as well as signs and symptoms of severe left ventricular dysfunction, were evaluated for coronary revascularization surgery. All had multiple vessel coronary artery disease and at least one prior myocardial infarction. Cardiac catheterization demonstrated abnormally elevated left ventricular end-diastolic pressure (LUEDP), low cardiac output, and depressed resting biplane systolic ejection fraction (SEF) ranging from 18 to 45 per cent (31 per cent). To evaluate potential myocardial function, a premature ventricular contraction was introduced during the ventriculogram and the SEF of the postextrasystolic potentiated (PESP) beat calculated and compared to a sinus beat SEF. Patients were separated into two groups based on the increase in SEF: those with greater than 0.10 augmentation (24 patients) and those with less than 0.10 augmentation (9 patients). Coronary revascularization was carried out with at least two bypass grafts in each patient. The operative mortality in those with more than 0.1 SEF augmentation was 9 per cent (2/24), late mortality rate 5 per cent (1/22), and 20/21 became Class I or II in the follow-up period of 11 to 57 months (25). Operative mortality in those with SEF augmentation of less than 0.1 3/9 33 per cent), late mortality rate 1/6, and only 1/5 achieved Class 1 status during the follow-up period of 10 to 35 months (22) postoperatively. These data suggest that significant augmentation of SEF by a premature ventricular contraction is a simple and useful indicator to aid in selection of patients with left ventricular dysfunction for coronary revascularization.

Adult↗
PubMed1975

Comparison of observer performance with 16 mm cinefluorography and 70 mm camera fluorography in coronary arteriography.

Clinical 16 mm cinefluorography and 70 mm camera fluorography were compared in 30 unselected patients undergoing coronary arteriography. Accuracy in detecting coronary arterial stenosis and collateral vessels and in assessing the degree of stenosis was similar with the two techniques. With both methods, there were significant inter- and intraobserver differences in estimating the degree of stenosis. These differences indicate that coronary arteriography is only a semiquantitative method for making decisions about treatment, prognosis and follow-up of patients. The use of more than one observer increases the likelihood that stenotic lesions will be detected. Interobserver variation in detecting collateral circulation is small.

Adult↗
PubMed1975

An additional angiographic sign for determining coronary artery dominance in obstructive coronary artery disease.

An additional angiographic sign for determining coronary artery dominance is proposed. This sign is based on the anatomic pattern of the infraventricular branches in the left anterior oblique view. It is especially helpful in patients in whom the right coronary and/or left circumflex coronary arteries are completely occluded and distal vessels are filled via collaterals.

Adult↗
PubMed1975

Abnormalities of left ventricular function and geometry in adults with an atrial septal defect. Ventriculographic, hemodynamic and echocardiographic studies.

Left ventricular function and motion in 12 adults with an ostium secundum atrial septal defect were analyzed utilizing biplane cineangiography. Values for left ventricular end-diastolic volume index, stroke volume index, ejection fraction, left ventricular end-diastolic pressure and mean rate of circumferential fiber shortening were compared with values in an age-matched group of 11 normal subjects. Comparisons of ventriculographic and echocardiographic data were also made in 5 patients and 10 control subjects. Cardiac index was smaller in patients than in the normal subjects (3.6 vs. 4.5 liters/min per m2, P less than 0.01). Although left ventricular end-diastolic pressure was similar (8 mm Hg in both groups), the end-diastolic volume index was significantly smaller in patients than in normal subjects (56 vs. 76 ml/m2, P less than 0.05). Stroke volume index was also significantly smaller in patients (40 vs. 52 ml/m2, P less than 0.01). The two groups had similar values for ejection fraction (65 +/- 2 percent [standard error of the mean] in patients vs. 68 +/- 2 percent in normal subjects), circumferential fiber shortening velocity (1.67 +/- 0.13 vs. 1.81 +/- 0.15 circumferences/sec.), heart rate (91 +/- 7 vs. 90 +/- 5 beats/min) and mean systemic arterial pressure (92 +/- 5 vs. 87 +/- 3 mm Hg). Early systolic bulging of the upper ventricular septum toward the right ventricle was seen in 10 of 12 patients with an atrial septal defect but in no normal subject. Echocardiographic data supported these findings. No other abnormalities of motion were consistently noted. It is concluded that the left ventricle of patients with an atrial septal defect is subnormal in volume and abnormal in sequence of contraction of the septum and is characterized by apparent decreased distensibility.

Adolescent↗
PubMed1975

The omnicardiogram: new approach to detection of heart disease in patients with a normal resting electrocardiogram.

The omnicardiogram is a new technique in which various leads of the standard electrocardiogram are digitized and subjected to a nonlinear mathematical transformation so as to detect subtle degrees of abnormality not apparent in the original electrocardiogram. Its usefulness in the detection of heart disease was studied in 121 male patients with a normal resting 12 lead electrocardiogram who underwent selective coronary cineangiography for a chest pain syndrome. In normotensive patients with a normal resting electrocardiogram, an abnormal omnicardiogram was recorded in 81 percent of those with three vessel disease, 67 percent of those with two vessel disease and 41 percent of those with one vessel disease. Nineteen percent of patients with normal coronary arteries or nonobstructive coronary artery disease had false positive tracings. The omnicardiogram was abnormal in 81 percent of patients with hypertension whether or not cornary artery disease was present. A double Master exercise test was performed by 109 of the 121 patients. In normotensive patients results of the test were positive in 67 percent of those with three vessel disease, 31 percent of those with two vessel disease and 14 percent of those with one vessel disease. There was a 4 percent rate of false positive tracings. Thus in our study, the omnicardiogram appeared to be superior to the Master test and to provide a useful new approach to detection of coronary artery disease in male patients with a normal resting electrocardiogram.

Coronary Angiography↗
PubMed1975

Relation between contractile reserve and prognosis in patients with coronary artery disease and a depressed ejection fraction.

Postextrasystolic potentiation (PESP) and 1-epinephrine infusion have previously been shown by the ventriculographic technique to augment left ventricular wall motion in patients with coronary artery disease. The present study relates the magnitude of this augmentation to short-term prognosis in 56 patients with coronary artery disease and a factor already identified with reduced life expectancy, i.e., an abnormal ejection fraction (EF less than .50). Forty-two patients received PESP and 14 1-epinephrine infusion. Based on severity of symptoms and technical suitability, 37 were treated surgically and 19 medically. Mean follwo-up times were 11.7 and 14.3 months, respectively. The mean increase in EF induced by PESP or 1-epinephrine infusion was significantly greater in patients who subsequently had good results from either surgical or medical therapy than in those who died or had progressive cardiac deterioration. In addition, those patients with an increase in EF of .10 or greater had a statistically greater chance of doing well than patients with less augmentation. Evaluation of change in ejection fraction after inotropic stimulation in patients with depressed ejection fractions is helpful in identifying those patients with greatest contractile reserve and hence better short-term prognosis with eigher medical or surgical therapy. Because of its ease of performance and greater enhancement of contractility, PESP is preferred to 1-epinephrine infusion as the inotropic stimulus of choice.

Cardiac Catheterization↗
PubMed1975

Vectorcardiographic diagnosis and electrocardiographic correlation in left ventricular asynergy due to coronary artery disease. I. Severe asynergy of the anterior and apical segments.

The transverse plane QRS loop vectorcardiogram (VCG) was analyzed in 102 consecutive patients, angiographically proven to have coronary artery disease (CAD), whose right anterior oblique left ventriculogram showed severe asynergy (akinesis or marked hypokinesis) of the anterior and apical segments. Eighty-four of the 102 loops were considered to be diagnostic of severe asynergy because similar loops were not found in patients with CAD with less severe asynergy of either or both segments or in normal control subjects. Eighty-two of the 84 showed a uniformly abnormal pattern. Posterior vectors exhibited partial or complete clockwise "rotation" and were much more prominent than early anterior forces. In fact, the latter were often absent. In the other two VCG's at least the early half of the loop displayed prominent anterior vectors. The ECGs showed marked variability of the QRS in leads V-2-V-6. Abnormal Q waves were present in only 63 of the 102. The numbers of these leads showing abnormal Q waves varied from one to all of these positions.

Bundle-Branch Block↗
PubMed1975

Ventricular function before and after direct revascularization surgery. A proposal for an index of vascularization to correlate angiographic and ventriculographic findings.

In order to determine the effect of direct bypass surgery on the total coronary arterial supply to the heart, a numerical construct was devised to incorporate the development of new obstructive lesions and the presence of patent or nonpatent grafts. This construct, termed a vascularization index (VI), was used to evaluate left ventricular function and anginal symptoms after coronary artery bypass surgery in 56 patients. Patients with an increase in local or total arterial blood supply (positive delts VI) often had similar directional changes in segmental wall motion and ventricular ejection fraction. Patients with a decrease in local or total arterial blood supply (negative delta VI), due to either nonpatent grafts or progression of atherosclerotic disease, also usually had similar directional changes in segmental wall motion and ventricular ejection fraction. (Although nearly all patients reported a decrease in anginal symptoms after surgery, delta VI could not identify degree of improvement.) Use of an integrated approach in describing pre and postoperative myocardial blood supply appears to be the most reliable method of explaining changes in left ventricular function.

Angiocardiography↗
PubMed1975

Prognosis in medically-treated coronary artery disease: influence of ejection fraction compared to other parameters.

The prognostic value of the left ventricular ejection fraction(EF) was compared to that of other commonly used indices--severity of coronary artery disease, left ventricular end-diastolic pressure, cardiac index, and abnormal ECG--in 144 patients with coronary artery disease followed for an average of 14 months on medical management. During this period, 14 patients (10%) died. Analysis of the mortality demonstrated that the EF was the most powerful predictor of short-term survival. Thus, patients with three-vessel coronary artery disease and anormal EF (greater than 0.50) had a significantly lower mortality (12%) than did patients with three-vessel CAD and a reduced EF (33%, P less than 0.001). Similar comparisons were observed within the subgroups with abnormal hemodynamics or an abnormal ECG. Therefore, the EF appears to be an important prognostic guide in the medical therapy of coronary artery disease, and is of significantly more discriminant value than other measurements when combined abnormalities exist.

Adult↗