Robert E. Fowles

Two dimensional echocardiographic assessment of patients with bioprosthetic valves

The clinical utility of two dimensional echocardiography in assessing bioprosthetic and left ventricular function was studied in 40 consecutive patients 1 week to 60 months after valve replacement surgery. These patients were referred to obtain normal baseline studies as well as to evaluate complications:suspected endocarditis, embolic phenomena and congestive heart failure of unknown cause. Independent M mode echocardiograms were also obtained in each patient. Confirmation of ultrasonic studies was by cardiac catheterization with angiography, surgery and pathologic study in 10 patients; cardiac catheterization with angiography alone in 7 patients; surgery and pathologic study in 3 patients; autopsy in 3 patients; blood cultures to confirm or exclude endocarditis in 10 patients; and confirmation on clinical grounds in 7 patients. Technically adequate two dimensional studies were recorded in 39 of 40 subjects. Two dimensional echocardiography accurately assessed 15 of 16 patients with an abnormal bioprosthetic valve and a normal left ventricle (1 of 16 patients had a false positive two dimensional echocardiogram); 8 of 8 patients suspected to have prosthetic valve or left ventricular dysfunction but who were normal; 7 of 7 patients with a normal prosthesis and an abnormal left ventricle; the one patient with an abnormal valve and left ventricle; and 7 of 7 clinically normal patients who were referred for baseline studies. In summary, the two-dimensional echocardiogram demonstrated a 97 percent diagnostic accuracy rate which was significantly greater than the 67 percent (P less than 0.001) for M mode echocardiography in the same group of patients. It is concluded that two dimensional echocardiography has excellent diagnostic accuracy in assessing bioprosthetic and left ventricular function and is superior to M mode echocardiography in evaluating patients after such valve replacement.

Apparent asymmetric septal hypertrophy due to angled interventricular septum.

Abstract A distinct geometric pattern is described in patients whose M mode echocardiogram falsely indicates asymmetric septal hypertrophy. Sixty-four patients were referred because of clinically suspected idiopathic hypertropic subaortic stenosis. Thirty-six of these patients had M mode echocardiograms showing asymmetric septal hypertrophy (septal/free wall ratio 1.3 or greater). On two dimensional study, only 16 of the 36 had this finding; each of the remaining 20 had a normal interventricular septum. The apparent asymmetric septal hypertrophy on M mode echocardiography was due to anterior angulation of the septum: The thickness of the septum was exaggerated because of its oblique orientation with respect to the path of the single dimensional echocardiographic beam. This anterior direction of the septum was indicated by measuring the angle between the mid line axis of the aortic root and that of the septum. In patients with apparent asymmetric septal hypertrophy this angle was lower (97 ° ± 2.6 ° [mean ± standard error of the mean]than in patients with true asymmetric septal hypertrophy (124 ° ± 2.9 °, p M mode echocardiograms were similar in the groups with apparent and true asymmetric septal hypertrophy with respect to septal velocity and percent thickening. The two groups were likewise similar with respect to clinical features (chest pain, palpitation, systolic murmur). The group with true asymmetric septal hypertrophy had a larger proportion of electrocardiographic abnormalities. Because of limitations in technique, M mode echocardiography may allow overdiagnosis of asymmetric septal hypertrophy in certain patients. When a more secure diagnosis of this abnormality is necessary, two dimensional echocardiography is helpful.

Coronary artery spasm in the denervated transplanted human heart: A clue to underlying mechanisms

The mechanism of coronary artery spasm has been poorly understood but there has been some suggestion that cardiac autonomic innervation may play an important role. We report coronary artery spasm in a 43 year old man two years after he had received a transplant. Provocative pharmacologic testing suggested functional denervation of the patients heart. Thus, coronary artery spasm can occur in the transplanted, denervated human heart. Autonomic innervation of the heart is not essential in all cases of coronary spasm, and circulating catecholamines and/or metabolic of hormonal products may play an important role.

Clinical and pathologic findings of myocarditis in two families with dilated cardiomyopathy

The use of endomyocardial biopsy and gallium-67 scans in patients with dilated cardiomyopathy (DCM) has demonstrated the presence of myocardial inflammation in a subset of patients. A family with DCM was studied with endomyocardial biopsy and gallium-67 scanning; both identified the presence of myocarditis in the proband. Evaluation of histologic sections from decreased family members revealed myocarditis as the principal pathologic finding. This patient identified during life demonstrated a defect in suppressor lymphocytic function and improved with immunosuppressive therapy. A second family with DCM was discovered when postmortem examination of the proband and his fathers heart showed myocarditis. A living sibling was identified with asymptomatic myocardial dysfunction. Longitudinal follow-up of surviving members of both families are in progress. This study indicates that thorough diagnostic evaluation of all patients with familial DCM should be pursued to identify subgroups with potentially treatable inflammation.

Left ventricular function at high altitude examined by systolic time intervals and M-mode echocardiography.

To better understand the effects of high-altitude hypoxia on cardiac performance, healthy lowland-residing volunteers were studied in 2 groups: 10 subjects after acute ascent to 12,500 ft (3,810 m) (acute group) and 9 subjects after chronic exposure for 6 weeks to 17,600 ft (5,365 m) and 11,000 ft (3,353 m) (chronic group). Systolic time intervals and M-mode echocardiograms were recorded at low and high altitudes. Heart rate was 21% greater at high altitude for all subjects. Preejection period/left ventricular ejection time (PEP/LVET) increased by 16% in the acute group and by 22% in the chronic group. Heart size was smaller at high altitude in both groups, with left atrial and left ventricular (LV) diameters decreasing by 10 to 12%. These changes were statistically significant (p less than or equal to 0.01). Despite the increase in PEP/LVET, echocardiographic measurements of LV function (percent fractional shortening and mean normalized velocity of circumferential fiber shortening) remained normal. LV isovolumic contraction time was shorter at high altitude, suggesting heightened, rather than depressed, contractility. LV function does not appear to deteriorate at high altitude. Alterations in systolic time intervals probably result from decreased preload, as reflected by smaller heart size, rather than from heart failure or depressed LV contractility.

Single and two dimensional echocardiographic features of the interatrial septum in normal subjects and patients with an atrial septal defect.

The interatrial septum is one of the least studied structures in M mode echocardiography. Two dimensional echocardiography has made it possible to record simultaneous M mode and two dimensional echocardiograms. Such studies were performed in 10 normal subjects and in 9 patients with a secundum atrial septal defect. In the short axis view of the base of the heart, the interatrial septum was visualized in the two dimensional studies as a linear echo running from the posterior aortic wall to the posterior atrial wall and in the M mode records as a series of dense echoes posterior to the aorta. The great variability in echo dropout of the interatrial septum made it impossible to distinguish the normal subjects from the patients with atrial septal defect. The dense echoes of the interial septum in the M mode records gave the false impression that they were filling the left atrium. These data indicate that (1) a secundum atrial septal defect cannot be reliably differentiated from a normal septum using these echocardiographic methods, and (2) the medial location of the interatrial septum should be appreciated so that it will not be confused with a left atrial mass.

Patients with congestive cardiomyopathy as cardiac transplant recipients: Indications for and results of cardiac transplantation and comparison with patients with coronary artery disease☆

In recent years end-stage congestive cardiomyopathy has become an increasingly frequent clinical diagnosis in candidates for cardiac transplantation. Forty-six patients who underwent transplantation because of congestive cardiomyopathy and 59 because of coronary artery disease were studied between 1971 and 1978 at Stanford University. The overall 1 year survival rate was similar in the two groups: cardiomyopathy-transplant, 64 percent and coronary artery disease-transplant, 55 percent. The survival rate has improved substantially for both groups within the last decade: The 3 year survival rate for cardiomyopathy-transplant patients undergoing cardiac transplantation since 1974 is nearly 60 percent. In contrast, 36 similarly ill patients with cardiomyopathy not undergoing transplantation had a 1 year survival rate of 23 percent and a 3 year survival rate of 4 percent (p less than 0.001). Survival rates in the cardiomyopathy-transplant group were unaffected by age (greater or less than 40 years). Patients in this group under age 40 had a lower frequency of infection (1 per 313 patient-days versus 1 per 195 patient-days in the older group, p less than 0.05) and a significantly longer interval to second rejection episodes (p less than 0.05), a measure of rejection frequency. Cardiomyopathy-transplant patients under age 40 had fewer deaths due to rejection (17 percent) compared with older patients in this group (36 percent). Cardiac transplantation is an effective treatment for end-stage congestive cardiomyopathy.

Relation of P-S4 interval to left ventricular end-diastolic pressure.

Reports have suggested that the interval between P wave onset and the fourth heart sound (P-S4 interval) reflects changes in left ventricular myocardial stiffness. We made simultaneous measurements of the P-S4 or atrial electrogram to S4 (A-S4) interval and left ventricular pressure in 19 patients with coronary artery disease who were studied before and after atrial pacing. Thirteen patients developed angina accompanied by significant rises in their end-diastolic pressure and a consistent decrease in P-S4 or A-S4 interval; whereas the six patients who had atrial pacing without the development of angina had no change in end-diastolic pressure, P-S4, or A-S4 interval. The resting data showed in inverse correlation between left ventricular end-diastolic pressure and the P-S4 interval. In addition, the P-S4 interval let us discriminate between patients with normal and abnormal end-diastolic pressure (greater than 15 mmHg).

Clinical electrophysiologic effects of tocainide

SUMMARYThe electrophysiologic properties of tocainide were evaluated by electrophysiologic studies in 11 patients before, during and after a constant intravenous infusion of the drug for 15 minutes. Peak plasma tocainide concentrations averaged 11.0 ± 1.7 Ag/ml (sEM), range 3.7 to 22.7. AH, HV, QRS, QTc and RR intervals were measured every 5 minutes during sinus and atrial-paced rhythms and showed small changes which were not statistically significant for HV and QRS. Mild shortening of RR was significant (P < 0.05) at 15 minutes only. AH tended to increase slightly for spontaneous (but not paced) rhythm, becoming significant at 15 minutes only (P < 0.05). QTc decreased slightly, a change which was significant (P < 0.05) for paced but not spontaneous rhythm. A progressive rise in mean arterial pressure occurred during drug infusion and persisted through 30 minutes (P < 0.001). Comparison of electrophysiologic studies at 0 and 30 minutes showed decreases in mean effective refractory periods of atrium. A-V node. and rieht ventricle by 17, 22, and 23 msec, respectively (P < 0.05, 0.01, 0.01). Functional refractory period of the A-V node showed an average 4ecrease which was not significant. Sinus node recovery time and Wenckebach cycle length were unchanged. The drug was well tolerated in all 11 patients. Hypotension in a twelfth patient may or may not have been drug related. These results obtained at therapeutic plasma concentrations suggest qualitative similarities between the conduction system effects of tocainide and those published for lidocaine.