Left ventricular mass in middle-aged men. Relationship to blood pressure, sympathetic nervous activity, hormonal and metabolic factors

Associations of insulin levels with left ventricular structure and function in American Indians: the strong heart study

We evaluated the association of insulin and echocardiographic left ventricular (LV) measurements in 1,388 (45% men) nondiabetic American Indian participants in the Strong Heart Study (SHS). Significant (all P < 0.05) relations were found in men and women between log(10) fasting insulin and LV mass (r = 0.24 and 0.26), left atrial diameter (r = 0.25 and 0.28), posterior wall thickness (r = 0.20 and 0.26), septal thickness (r = 0.19 and 0.24), LV diameter (r = 0.17 and 0.16), and cardiac output (r = 0.20 and 0.24) and in women relative wall thickness (r = 0.11) and peripheral resistance (r = -0.17). In regression analyses, adjusting for BMI, age, height, and systolic pressure, fasting insulin was independently correlated with cardiac output in men and relative wall thickness and septal thickness in women (all P < 0.05). The 97th percentiles of fasting insulin (25 microU/ml for men, and 23 microU/ml for women) in 163 apparently normal (BMI <26; blood pressure <140/90; and absence of diabetes, valvular disease, LV wall motion abnormality, or antihypertensive treatment) SHS participants were used to separate normal from elevated fasting insulin levels. Adjusting for age, BMI, and height, men with elevated insulin levels had larger LV diameters (5.41 vs. 5.16 cm; P = 0.05), higher cardiac output (5.5 vs. 4.9 l/min; P < 0.001), and lower peripheral resistance (1,487 vs. 1,666; P = 0.01), paralleling results of regression analyses. Positive relations between insulin and heart size in nondiabetic adults are largely due to associations with body size; after adjustments for covariates, fasting insulin levels are related to greater LV size and cardiac output in men and more concentric LV geometry in women.

Relevance of heart rate as a risk factor in hypertension

Numerous studies have shown that resting heart rate is closely correlated with blood pressure and that it is prospectively related to the development of hypertension. Moreover, there is mounting evidence to indicate that a high heart rate is associated with increased cardiovascular morbidity and mortality. In this respect, heart rate can be considered both as a marker of risk and as an independent factor in the induction of risk. Sympathetic overactivity seems to be responsible for the increase in blood pressure and hematocrit, and for the metabolic abnormalities often observed in subjects with tachycardia. Experimental studies in monkeys have shown that heart rate can also exert a direct atherogenic action on the arteries through increased wall stress. Furthermore, tachycardia can favor the occurrence of ventricular arrhythmias and sudden death. Reduction of heart rate appears to be a reasonable additional goal of antihypertensive therapy, especially in subjects with increased sympathetic tone. Nondihydropyridine calcium antagonists and drugs with agonistic properties at the I1-imidazoline receptors of the rostral ventrolateral medulla may be drugs of choice for this purpose, but whether they offer a significant morbidity-mortality advantage must be proven in prospective trials.

Dyspnoea of cardiac origin in 67 year old men: (2). Relation to diastolic left ventricular function and mass. The study of men born in 1913

The relation of cardiac dyspnoea to diastolic left ventricular dysfunction was examined in a sample of 67 year old men from the general population of Gothenburg, Sweden. Forty two men with cardiac dyspnoea and 45 controls were selected from the screened cohort of 644 men. M mode echocardiography, apexcardiography, and phonocardiography were used to evaluate heart sounds, diastolic time intervals, aortic root motion (atrial emptying index); peak rate of change in left ventricular dimension, left atrial and ventricular size; and left ventricular mass. There was a significant relation between dyspnoea grade and left ventricular mass and posterior wall thickness. Dyspnoea grade also correlated significantly with the amplitude of the rapid filling wave and the third heart sound, atrial emptying index and left atrial size, the pulmonary component of the second heart sound, and the dimension of the right ventricle. In mild to moderate dyspnoea fractional shortening was normal, but posterior wall thickness and left atrial dimension were increased. The time from the second heart sound to the O point of the apexcardiogram, adjusted for heart rate, was significantly prolonged in mild to moderate dyspnoea, but not in severe dyspnoea. There was a significant decrease of rate adjusted isovolumic relaxation time, probably secondary to altered loading conditions, in severe dyspnoea, but not in mild to moderate dyspnoea. When the effect of systolic function was excluded multivariate analyses showed that the relation between dyspnoea grade and left atrial dimension persisted. The finding that diastolic abnormalities of the heart contributed to the generation of cardiac dyspnoea may have implications for treatment.