Michael Sesto

Myocardial structure and function in patients with aortic valve disease and their relation to postoperative results

Abstract Left ventricular angiographic studies were performed before and 6 months after aortic valve replacement with a Bjork-Shiley prosthesis in 21 patients, 5 with aortic stenosis, 8 with mixed aortic valve lesions and 8 with aortic insufficiency. The degree of myocardial fibrosis and myocardial ultrastructural changes were evaluated from transmural needle biopsy specimens obtained from the left ventricular anterior free wall at operation. Twelve patients without heart disease served as control subjects for angiographic data. Patients with aortic valve disease had a significantly higher left ventricular mass before operation than control subjects and a lower ejection fraction and mean normalized systolic ejection rate. After operation left ventricular mass decreased considerably but did not reach normal level. Ejection fraction and mean normalized systolic ejection rate became normal in all patients with aortic valve disease. The percent fibrosis determined with morphometry was significantly higher in the subendocardium than in the subepicardium of pressure-overloaded hearts (predominant stenosis) (19 versus 13 percent) but equal in both layers of volume-overloaded hearts (predominant regurgitation) (19 versus 18 percent). Electron microscopy revealed significant intracell alterations of the nucleus, sarcomeres, mitochondria and cytoplasmic reticulum. When all patients, regardless of type of aortic valve lesion, were considered, there was no significant correlation before operation between percent fibrosis and ejection fraction ( r 0.10) or mean normalized systolic ejection rate ( r 0.02) but a significant inverse relation between left ventricular mass and ejection fraction ( r 0.54) as well as mean normalized systolic ejection rate ( r 0.49). These data suggest that (1) Depressed left ventricular function in aortic valve disease is associated with ultrastructural degenerative cell changes, but complete recovery of cardiac function after aortic valve replacement is not prevented by these changes. (2) Interstitial myocardial fibrosis is not a primary determinant of depressed cardiac function in aortic valve disease.

Impaired left ventricular function in chronic aortic valve disease: survival and function after replacement by Björk-Shiley prosthesis.

Postoperative survival and left ventricular function were studied in 128 patients who underwent isolated aortic valve replacement by the Bj6rk-Shiley valve between 1973 and 1977. The average follow-up was 2.1 years. Patients with associated coronary artery disease or mitral valve disease were excluded. Preoperative ejection fraction ranged from 15-84%. Forty-two patients were restudied by cardiac catheterization 9.1 ± 1.1 months (mean ± SEM) after valve replacement. The hospital mortality was 11%. Preoperative type of valve lesion, functional class, cardiothoracic ratio, and ejection fraction (EF) had no significant effect on postoperative survival up to 4 years. After operation, left ventricular mass (LVMI) and peak systolic wall stress (PSWS) fell significantly, while EF and mean normalized systolic ejection rate (MNSER) increased in aortic stenosis and in aortic insufficiency. Neither in aortic stenosis nor in aortic insufficiency was there a significant relation between preoperative ejection fraction and postoperative LVMI, EF, MNSER and PSWS. We attributed this to a marked improvement of left ventricular function in patients with preoperative impaired ventricular function. Six patients with paravalvular leak at restudy had a significantly lower EF and MNSER, and a higher PSWS than patients without leak. Patients without leak had normal EF, MNSER and PSWS when compared with 10 normal persons, but LVMI remained moderately elevated. Postoperative transprosthetic gradient was 11.9 mm Hg (range 0-64 mm Hg).We conclude that impaired cardiac function is completely restored after aortic valve replacement by Bjork- Shiley valve, if valve function is good. Patients with impaired cardiac function preoperatively did not have a poorer prognosis after operation than patients with normal function.

Effect of coronary collaterals on left ventricular function at rest and during stress

Abstract The influence of coronary collateral vessels on resting left ventricular function was investigated in 87 consecutive patients with complete coronary artery occlusion of at least one of the three major coronary vessels. The morphology of coronary and collateral circulation was evaluated by coronary arteriography. Left ventricular function was assessed by biplane ejection fraction and segmental wall motion was evaluated by hemiaxes shortening. Collaterals to occluded arteries were graded as good or poor, according to the caliber of the distal vessel segment. Patients were divided into those with good collaterals (n =35), and those with poor or absent collaterals (n = 52), furthermore, these two groups were subdivided according to the location of coronary artery occlusion. Collateralized single vessel occlusions were found more frequently than collateralized multiple vessel occlusions. Ejection fraction and segmental wall motion was significantly better in well collateralized occlusions than in poorly collateralized occlusions of LAD or RC and was normal or depressed only slightly if compared to 17 patients without heart disease. In contrast, total and regional myocardial function was severely depressed in poorly collateralized LAD or RC occlusion. Ventriculography after rapid ventricular pacing was performed in 12 of 87 patients with well collateralized or poorly collateralized LAD occlusion to evaluate to what extent coronary collaterals protect anterior wall motion during increased oxygen demand. Pacing induced a drastic fall of anterior wall motion in well collateralized segments whereas no change was found in poorly collateralized segments. Reviewing clinical data of two patient groups with comparable numbers and locations of occlusions revealed in the well collateralized group more severe angina (p

Failure of aneurysmectomy to improve left ventricular function.

Biplane left ventricular angiography was performed in 22 patients with isolated obstructive disease of the anterior descending branch of the left coronary artery and with an anterior aneurysm following transmural myocardial infarction. Six patients were restudied between 6 and 10 months after aneurysmectomy. Left ventricular reserve was estimated by analysis of a spontaneous postextrasystolic beat. Using angiographic techniques a contractile section, a transitional section, and a noncontractile section were identified. From the surgical patients the excised aneurysm and a transmural needle biopsy of the transitional section were investigated by light microscopy. With increasing volumes of noncontractile and transitional sections, total end-diastolic volume (r = 0.81, P less than 0.001) and end-systolic volume (r = 0.94, P less than 0.001) increased linearly, while the ejection fraction decreased (r = 0.70, P less than 0.001). No relation was found between the combined volumes of the noncontractile and transitional sections on the one hand, and the end-diastolic volume, the end-systolic volume, or the ejection fraction of the contractile section on the other hand. After aneurysmectomy a significant decrease was found in end-diastolic volume (194 to 133 ml/m2, P less than 0.001) and end-systolic volume (124 to 83 ml/m2, P less than 0.001) but no change occurred in ejection fraction (35 to 37%) and left ventricular end-diastolic pressure (23 to 25 mmHg). Surgical resection included part of the transitional section, which before surgery had an average ejection fraction of 27 per cent during a normal beat, rising to 41 per cent in a postextrasystolic beat. The transitional section after surgery now formed a large akinetic area of the anterior wall. We conclude that aneurysmectomy in isolated left anterior descending artery disease with anterior aneurysm fails to improve left ventricular function because the effect of reduction of left ventricular volumes is offset by the destruction of contractile behaviour in the transitional section.

Vagal tone, significance of electrophysiologic findings and clinical course in symptomatic sinus node dysfunction

Abstract The relation of hypersensitive carotid sinus syndrome (HCSR) to sick sinus syndrome (SSS) is not clear; vagal role, relevance of electrophysiological testing, and the natural course of both syndromes are ill defined. In 186 symptomatic patients, resting heart rate (HR), carotid sinus pressure results (CSP), and corrected sinus node recovery time (CSRT) were determined before and after atropine (A). According to test results 102 patients had HCSR (group I), 33 had HCSR + SSS (group II), 30 patients had isolated SSS (group III) and 20 served as control (group IV). HR below 60 b.p.m. in groups I to III and lower than controls (p 0.05), which implies increased vagal tone in HCSR but destructive affection of the SA node in SSS. Bradycardia, S-A block, supraventricular tachyarrhythmias and the combination of dizziness and syncope served as diagnostic clues for HCSR or SSS in a limited number of patients. CSP and CSRT separated HCSR from SSS but failed to predict syncope in groups I to III (p > 0.05) and thereby cannot aid the indication for pacer application. SSS test results remained unchanged over 16 months showing an unfavorable prognosis. We conclude that HCSR and SSS, although frequently occurring together, are entities made separate by specific testing, which, however, fails to aid in therapeutic decision-making. Vagal tone plays but one role in HCSR and SSS and electrophysiologic pathology of SSS does not improve in its course.

Regional myocardial function at rest and after rapid ventricular pacing in patients after myocardial revascularization by coronary bypass graft or by collateral vessels

Abstract The relation between the anatomy of the left anterior descending coronary artery and regional myocardlal function was studied at rest and after rapid ventricular pacing in 194 patients with proximal disease of this artery. Sixty patients were restudied 4 months after coronary bypass surgery. All of these patients had a graft to the left anterior descending coronary artery after operation. Twenty-two persons with normal coronary arteriograms served as control subjects. Coronary obstruction was measured with quantitative coronary artertography and was classified as critical stenosis (75 to 99 percent luminal narrowing) or occlusion (100 percent). Regional wall motion was defined by hemiaxls shortening. Four groups were established: group A, obstruction without revascularization; group B, obstruction with revascularization by collateral vessels; group C, obstruction with revascularization by a patent graft; group D, obstruction with revascularization by a stenosed or occluded graft. At rest, regional motion diminished in group A with critical stenosis and further with occlusion (from 39 to 25 percent and to 5 percent, P P P P > 0.05). In contrast, in group C motion remained unchanged (from 39 to 31 percent and to 32 percent, P > 0.05, P > 0.05). After pacing, regional motion became akinetic in groups A and B with critical stenosis and remained unchanged with occlusion. In contrast, in group C wall motion remained normal after pacing with critical stenosis and with occlusion. Results in group D were comparable with those in group B. Ejection fraction showed parallel and left ventricular end-diastolic pressure inverse changes as compared with regional motion. When coronary stenosis progresses to occlusion without revascularization, myocardial contractility becomes depressed at rest and after pacing. Revascularization by collateral vessels preserves resting function in coronary occlusion to some extent but is ineffective after pacing. Successful surgical revascularization prevents loss of function at rest and after pacing in critical stenosis and in occlusion.

Cardiac reserve during isoproterenol stress in patients with aortic valve disease before and after corrective surgery

Abstract The relations between left ventricular (LV) hypertrophy as estimated by LV mass and LV function and between LV hypertrophy and cardiac reserve were evaluated in 26 patients with aortic valve disease and in nine normal patients who served as controls. Ejection fraction (EF) and mean circumferential fiber shortening rate (VCF) served as indices of LV function. Reserve force of the left ventricle was tested by ventriculography during infusion of 0.3 μg/Kg. body weight/min. isoproterenol. EF and VCF were not significantly different (p > 0.05) either at rest or during isoproterenol infusion if patients with aortic stenosis were compared to patients with aortic regurgitation having comparable LV masses. Therefore we correlated the EF and VCF to the LV mass of all patients irrespective of the type of aortic valve lesion. Poor but significant inverse correlations were found at rest between LV mass and EF (r = 0.62) and between LV mass and VCF (r = 0.57). These correlations improved considerably during isoproterenol: r = 0.84 for EF and r = 0.74 for VCF. LV function was evaluated in another six patients with aortic valve disease before and nine months after successful aortic valve replacement by Bjork-Shiley prostheses. LV mass before surgery was 3.6 times control and decreased after surgery to 1.7 times control (p