Left Congestive Heart Failure Research Articles

Left Ventricular Myocardial Function in a Cat with Nonspecific Cardiomyopathy Phenotype

Background: Non-specific phenotype feline cardiomyopathy (CFNE) is one that does not fit properly in the other categories, and it is necessary to describe in detail the morphology and cardiac function. The causes of CFNE is not very clear, and it may be due to congenital or acquired disease, or also to primary or secondary myocardial dysfunction associated with other conditions. In symptomatic cases, the clinical signs observed are compatible with left congestive heart failure (ICCE). This study reports a CFNE case in an asymptomatic cat, in order to demonstrate the importance of echocardiographic examination in the early diagnosis of the disease.Case: A 6.5-year-old non-neutered crossbred cat weighing 3.1 kg was seen at the institution's veterinary hospital for routine cardiac evaluation. No clinical signs were reported in the history. On physical examination, the animal presented calm behavior, body score 5/9, heart rate 200 bpm, systolic blood pressure of 102 mmHg, respiratory rate 64 mrp, and other normal parameters. CBC and urinalysis laboratory tests were requested, which were unchanged. The electrocardiogram showed normal patterns. In the conventional echocardiographic examination, a significant increase in the left atrium (LA) was observed, and the LA/Ao ratio was 2.05 and the diastolic function was abnormal. There was no presence of concentric hypertrophy of the left ventricle (LV), the thickness of the ventricular wall measured at different points, in the two-dimensional mode and the M mode, was less than 5 millimeters. Other parameters of conventional echocardiography were within the normal range. Through these echocardiographic findings, the suggestive diagnosis was non-specific phenotype cardiomyopathy, with a significant increase in LA. For the assessment of left ventricular myocardial deformation, the strain (St%) and strain rate (StR 1/s) indexes (which correspond to the percentage and speed at which the myocardial fiber deforms during the cardiac cycle, respectively) were evaluated using two-dimensional feature tracking (2D-FTI), with the aid of Xstrain version 10.1 software, optical flow algorithm (ESAOTE®). This analysis showed a decrease in the overall value of the longitudinal and radial St/StR variables.Discussion: The CFNE echocardiographic examination can demonstrate several structural cardiac changes that are not characterized in any other category of cardiomyopathy. Although the patient is still asymptomatic, the echocardiogram made it possible to identify structural changes compatible with the reported disease (enlargement of the left atrium and left ventricular myocardial deformation). Using the 2D-FTI technique, the vulnerability of the myocardial fibers in the longitudinal and radial directions of the left ventricle was observed, demonstrating that despite the patient still not showing clinical signs, there were already signs of ventricular dysfunction. These changes observed by the 2D-FTI technique, suggest that the patient may develop clinical signs of ICCE, resulting from pleural effusion and/or pulmonary edema, requiring more frequent reassessments. For this reason, animals with CFNE should undergo periodic cardiac evaluation to monitor the evolution of the patient's clinical condition. The use of more specific tools, such as 2D-FTI, allows an earlier assessment of clinical changes, which provides a faster therapeutic intervention when necessary, preventing the patient from abruptly decompressing.

Arrhythmogenic effect of flecainide toxicity

Flecainide is a class 1C antiarrhythmic drug especially used for the management of supraventricular arrhythmia. In overdose cases, flecainide can induce life treating ventricular arrhythmias and cardiogenic shock. We report the case of a 72-year-old woman admitted to our intensive care unit for a regular monomorphic wide complex tachycardia (QRS duration 240 ms, right bundle branch block and superior axis morphology) without apparent P waves. Clinical examination showed slight left congestive heart failure signs without cardiogenic shock. An intravenous bolus of 10 mg adenosine 5'-triphosphate (ATP) was ineffective to stop the tachycardia. The diagnosis of ventricular tachycardia induced by flecainide overdose was considered. 500 mL of intravenous 84‰ sodium bicarbonate was administrated. The patient's QRS narrowed immediately and 12-lead ECG showed sinus rhythm. Blood samples confirmed the flecainide overdose and the clinical status progressively improved.

Reversible congestive heart failure in severe hypocalcemia

We present a case of severe congestive left heart failure due to profound and long-term hypocalcemia caused by surgically induced hypoparathyroidism. Hypocalcemia as a potential contributor to heart failure should be included in the differential diagnosis of all patients with congestive heart failure who do not respond adequately to the usual treatment. By rapid correction of the serum calcium level unnecessary diagnostic and therapeutic measures might be avoided. In addition, being aware of and treating hypocalcemia is crucial since this kind of heart failure is completely reversible with calcium and vitamin D treatment.The pivotal role of calcium in molecular and cellular biology is well known, but its clinical importance in day-to-day practice is often underestimated. Although some cases of heart failure resulting from hypocalcemia secondary to hypoparathyroidism have been published in the last 20 years, this subject is still poorly documented in almost all current textbooks.

Central thromboembolism is a possible predictor of right heart dysfunction in normotensive patients with acute pulmonary embolism

Background Right heart dysfunction is a crucial factor in risk stratification of normotensive patients with pulmonary embolism. Apart from biomarkers, determinants of right heart dysfunction in this group of patients are not yet well established. Aim and method In order to identify such determinants, we analysed data of 252 patients with acute pulmonary embolism admitted to our hospital in 2008. Results 69 out of 140 patients showed right heart dysfunction by echocardiography within 24 hours after diagnosis, 71 did not. Right ventricular dysfunction was significantly more frequent in patients with central clots on computed tomography (p = 0.004), a history of syncope (p < 0.001) and among women on oral contraceptives (p = 0.003). In multiple regression analysis, only central thromboembolism (p < 0.001) was identified as individual predictor of right ventricular dysfunction. Age, gender, body mass index, idiopathic or recurrent thromboembolism, duration of symptoms, preceding surgery, room air oxygen saturation, carcinoma, hypertension, diabetes, renal disease, congestive left heart failure and concomitant lung disease were equally distributed. In comparison with NT-pro brain natriuretic peptide (PPV 67%, NPV 75%, p = 0.782) and troponin I (PPV 76%, NPV 62%, p = 0.336), central thromboembolism has shown to have a greater statistical power in predicting right heart dysfunction in normotensive patients with pulmonary embolism (PPV 78%, NPV 88%, p < 0.001). Conclusion Among normotensive patients with acute pulmonary embolism, those with central clots seem to be at greater risk for echocardiographically evaluated right ventricular dysfunction.

Skeletal muscle dysfunction in patients with idiopathic pulmonary arterial hypertension

Dyspnea and exercise limitation are common in patients with idiopathic pulmonary arterial hypertension (IPAH). Recently, a reduction in inspiratory and expiratory muscle strength has been observed in IPAH. However, it has not been investigated whether this respiratory muscle weakness might be part of a general muscle dysfunction as observed in congestive left heart failure. Therefore, in 24 consecutive IPAH patients (16 female; age 58.7+/-16.2; WHO class II-III; systolic pulmonary artery pressure during echocardiography at rest (sPAP) 65.0+/-20.6 mmHg, and 6-min-walk test (6-MWT) 473.6+/-127.7 m), the maximal isometric forearm muscle strength (best of three hand grip manoeuvres), maximal inspiratory and expiratory mouth occlusion pressures (Pimax, Pemax) were prospectively evaluated. The isometric forearm muscle strength was significantly lower in IPAH patients (281.7+/-102.6N) than in matched 24 healthy controls (397.1+/-116.8 N; p=0.03). In IPAH patients, there was a correlation between maximal isometric forearm muscle strength and 6-MWT (r=0.67; p=0.0007) and both, Pimax (r=0.69; p=0.0003) and Pemax (r=0.63; p=0.01), respectively. There was no correlation between forearm muscle strength and sPAP (r=0.30; p=0.16). The present skeletal muscle dysfunction is a novel finding in patients with IPAH. The correlation with respiratory muscle dysfunction and severity of disease might indicate a generalised "myopathy" in IPAH.

Role of renin-angiotensin system in development of heart failure induced by myocardial infarction in rats

We investigated the morphologic and functional changes of infarcted rat hearts under a paradigm of angiotensinconverting enzyme inhibition. Myocardial infarction was induced by left coronary artery ligation and a control group (SHAM) underwent sham-operation. Infarcted rats received normal drinking water with (CAP group) or without (INF group) captopril. Functional assessment was performed by electro (ECG) and echocardiogram (ECHO) just before and 21 days after surgery. The ECG of INF and CAP showed similar values and resembled healed infarct after surgery. The most outstanding differences between INF and CAP were the prevention of the increase of P-wave and attenuation both in rightward deviation of the QRS axis and Q-wave amplitude in CAP compared with INF. The ECHO showed that captopril treatment improved the diastolic filling more than systolic performance. Cardiac dilatation and left congestive heart failure were observed only in INF. Both infarcted groups showed a scar tissue in the left ventricular wall, but the INF showed a higher scar area than CAP (49.7+/-5.24 vs. 22.33+/-6.19 respectively). These data suggest that the renin-angiotensin system induces morphologic and functional changes in post-infarcted rat hearts and which can be assessed by non-invasive exams.

Evaluation of Right Ventricular Function in Patients With Congestive Left Heart Failure by the Doppler Derived Total Cardiac Performance Index (TEI index)

Background. This study aimed to assess the serial changes of right ventricular (RV) function in patients with congestive heart failure (CHF) from the acute to the convalescent stage using the Doppler derived total cardiac performance index (TEI index).Methods. Sixteen patients (11 men; mean age, 67 years) with acute left heart failure and sinus rhythm were studied by two-dimensional and Doppler echocardiography during the acute and convalescent stages of CHF. The ratio of early to late diastolic filling velocity (E/A) of both ventricles and the volume and ejection fraction of the left ventricle (LV) were measured. The isovolumic contraction (RVICT), relaxation times (RVIRT), and the ejection time (RVET) were measured from the recordings of the RV inflow or outflow velocities and the electrocardiogram. The RV TEI index was calculated as (RVICT + RVIRT) / RVET.Results. During the acute stage, the RVICT and RVIRT were prolonged, the RVET was shortened, and subsequently the RV TEI index was increased. As the condition improved, the RVICT and RVIRT were shortened, the RVET was prolonged, and the RV TEI index was significantly decreased along with a decrease in the LV volume and an increase in the LV ejection fraction.Conclusions. The RV TEI index seems to be useful for evaluating global RV function in patients with congestive left heart failure.

Tissue Doppler Imaging and Gradient Echo Cardiac Magnetic Resonance Imaging in Normal Cats and Cats with Hypertrophic Cardiomyopathy

Cats with hypertrophic cardiomyopathy (HCM) often develop diastolic dysfunction, which can lead to development of left congestive heart failure. Tissue Doppler imaging (TDI) echocardiography has emerged as a useful, noninvasive method for assessing diastolic function in cats. Cardiac magnetic resonance imaging (cMRI) has been performed in cats and accurately quantifies left ventricular (LV) mass in normal cats. However, assessment of cardiac function in cats by cMRI has not been performed. Six normal Domestic Shorthair cats and 7 Maine Coon cats with moderate to severe HCM were sedated, and TDI of the lateral mitral annulus was performed. Peak early diastolic velocity (Em) was measured from 5 nonconsecutive beats. Cats were anesthetized with propofol and electrocardiogram‐gated gradient echo cMRI was performed during apnea after hyperventilation. Short‐axis images of the LV extending from the mitral annulus to the apex were obtained throughout the cardiac cycle. LV mass at end systole and LV volumes throughout the cardiac cycle were quantified according to Simpson's rule. To assess the possible influence of propofol on diastolic function, TDI was performed on the 7 cats with HCM while sedated and then while anesthetized with propofol. Em was significantly lower in cats with HCM than normal cats (6.7±1.3 cm/s versus 11.6±1.9 cm/s,P&lt;.001, respectively). There was no difference in the cMRI indices of diastolic function in normal and HCM cats. Propofol did not reduce diastolic function (Em) in cats with HCM but mildly reduced systolic myocardial velocity (S) in Maine Coon cats with HCM that were anesthetized with propofol (P= .87 andP= .03, respectively).

Immediate and Late Outcomes of Transarterial Coil Occlusion of Patent Ductus Arteriosus in Dogs

Records from dogs (n = 125) that underwent attempted transarterial coil occlusion of patent ductus arteriosus (PDA) at the University of California, Davis, between 1998 and 2003, were reviewed, and a subset of these dogs (n = 31) in which the procedure was performed at least 12 months earlier were reexamined to determine long-term outcome. Coil implantation was achieved in 108 dogs (86%). Despite immediate complete ductal closure in only 34% of dogs, the procedure was hemodynamically successful as evidenced by a reduction in indexed left ventricular internal diameter in diastole (LVIDd; P < .0001), fractional shortening (P < .0001), and left atrial to aortic ratio (LA: Ao; P = .022) within 24 hours. Complete ductal closure was documented in 61% of dogs examined 12 to 63 months after coil occlusion. Long-standing residual ductal flow in the other 39% of dogs was not associated with increased indexed LVIDd or LA: Ao and was not hemodynamically relevant. Repeat intervention was deemed advisable in only 4 dogs with persistent (n = 1) or recurrent (n = 3) ductal flow. Complications included aberrant embolization (n = 27), death (n = 3), ductal reopening (n = 3), transient hemoglobinuria (n = 2), hemorrhage (n = 1), aberrant coil placement (n = 1), pulmonary hypertension (n = 1), and skin abscessation (n = 1). Serious infectious complications did not occur despite antibiotic administration to only 40% of these dogs. Transarterial coil occlusion was not possible in 14 dogs (11%) because of coil instability in the PDA and was associated with increased indexed minimum ductal diameter (P = .03), LVIDd (P = .0002), LVIDs (P = 0.001), and congestive left heart failure (P = .03) reflecting a relatively large shunt volume.

Immediate and Late Outcomes of Transarterial Coil Occlusion of Patent Ductus Arteriosus in Dogs

Records from dogs (n = 125) that underwent attempted transarterial coil occlusion of patent ductus arteriosus (PDA) at the University of California, Davis, between 1998 and 2003, were reviewed, and a subset of these dogs (n = 31) in which the procedure was performed at least 12 months earlier were reexamined to determine long‐term outcome. Coil implantation was achieved in 108 dogs (86%). Despite immediate complete ductal closure in only 34% of dogs, the procedure was hemodynamically successful as evidenced by a reduction in indexed left ventricular internal diameter in diastole (LVIDd; P &lt; .0001), fractional shortening (P &lt; .0001), and left atrial to aortic ratio (LA: Ao; P = .022) within 24 hours. Complete ductal closure was documented in 61% of dogs examined 12 to 63 months after coil occlusion. Long‐standing residual ductal flow in the other 39% of dogs was not associated with increased indexed LVIDd or LA: Ao and was not hemodynamically relevant. Repeat intervention was deemed advisable in only 4 dogs with persistent (n = 1) or recurrent (n = 3) ductal flow. Complications included aberrant embolization (n = 27), death (n = 3), ductal reopening (n = 3), transient hemoglobinuria (n = 2), hemorrhage (n = 1), aberrant coil placement (n = 1), pulmonary hypertension (n = 1), and skin abscessation (n = 1). Serious infectious complications did not occur despite antibiotic administration to only 40% of these dogs. Transarterial coil occlusion was not possible in 14 dogs (11%) because of coil instability in the PDA and was associated with increased indexed minimum ductal diameter (P= .03), LVIDd (P= .0002), LVIDs (P= 0.001), and congestive left heart failure (P= .03) reflecting a relatively large shunt volume.

Tissue Doppler Imaging and Gradient Echo Cardiac Magnetic Resonance Imaging in Normal Cats and Cats with Hypertrophic Cardiomyopathy

Cats with hypertrophic cardiomyopathy (HCM) often develop diastolic dysfunction, which can lead to development of left congestive heart failure. Tissue Doppler imaging (TDI) echocardiography has emerged as a useful, noninvasive method for assessing diastolic function in cats. Cardiac magnetic resonance imaging (cMRI) has been performed in cats and accurately quantifies left ventricular (LV) mass in normal cats. However, assessment of cardiac function in cats by cMRI has not been performed. Six normal Domestic Shorthair cats and 7 Maine Coon cats with moderate to severe HCM were sedated, and TDI of the lateral mitral annulus was performed. Peak early diastolic velocity (Em) was measured from 5 nonconsecutive beats. Cats were anesthetized with propofol and electrocardiogram-gated gradient echo cMRI was performed during apnea after hyperventilation. Short-axis images of the LV extending from the mitral annulus to the apex were obtained throughout the cardiac cycle. LV mass at end systole and LV volumes throughout the cardiac cycle were quantified according to Simpson's rule. To assess the possible influence of propofol on diastolic function, TDI was performed on the 7 cats with HCM while sedated and then while anesthetized with propofol. Em was significantly lower in cats with HCM than normal cats (6.7 +/- 1.3 cm/s versus 11.6 +/- 1.9 cm/s, P < .001, respectively). There was no difference in the cMRI indices of diastolic function in normal and HCM cats. Propofol did not reduce diastolic function (Em) in cats with HCM but mildly reduced systolic myocardial velocity (S) in Maine Coon cats with HCM that were anesthetized with propofol (P = .87 and P = .03, respectively).

Comparative value of Doppler echocardiography and B-type natriuretic peptide assay in the etiologic diagnosis of acute dyspnea

ObjectivesWe compared the accuracy of B-type natriuretic peptide (BNP) assay with Doppler echocardiography for the diagnosis of decompensated congestive left-heart failure (CHF) in patients with acute dyspnea. BackgroundBoth BNP and Doppler echocardiography have been described as relevant diagnostic tests for heart failure. MethodsOne hundred sixty-three consecutive patients with severe dyspnea underwent BNP assay and Doppler echocardiogram on admission. The accuracy of the two methods for etiologic diagnosis was compared on the basis of the final diagnoses established by physicians who were blinded to the BNP and Doppler findings. ResultsThe final etiologic diagnosis was CHF in 115 patients. Twenty-four patients (15%) were misdiagnosed at admission. The BNP concentration was 1,022 ± 742 pg/ml in the CHF subgroup and 187 ± 158 pg/ml in the other patients (p < 0.01). A BNP cutoff of 300 pg/ml correctly classified 88% of the patients (odds ratio [OR] 85 [19 to 376], p < 0.0001), but a high negative predictive value (90%) was only obtained when the cutoff was lowered to 80 pg/ml. The etiologic value of BNP was low in patients with values between 80 and 300 pg/ml (OR 1.85 [0.4 to 7.8], p = 0.4) and also in patients who were studied very soon after onset of acute dyspnea. Among the 138 patients with assessable Doppler findings, a “restrictive” mitral inflow pattern had a diagnostic accuracy for CHF of 91% (OR 482 [77 to 3,011], p < 0.0001), regardless of the BNP level. ConclusionsBedside BNP measurement and Doppler echocardiography are both useful for establishing the cause of acute dyspnea. However, Doppler analysis of the mitral inflow pattern was more accurate, particularly in patients with intermediate BNP levels or “flash” pulmonary edema.

Increased erythropoietin synthesis in patients with COLD or left heart failure is related to alterations in renal haemodynamics.

The mechanisms controlling erythropoietin (EPO) synthesis by the kidney in patients with chronic obstructive lung disease (COLD) or congestive left heart failure (CLHF) remain incompletely understood. Renal dysfunction occurs as a consequence of decreased renal blood flow (RBF) in these diseases. Because alterations in renal haemodynamics may affect EPO synthesis and red blood cell production, we investigated the potential relationships between renal function and plasma EPO synthesis in patients with COLD or CLHF. Thirty-two patients with COLD and 13 with CLHF underwent determination of renal physiology parameters, plasma EPO levels and haemoglobin levels. Plasma EPO concentrations were increased in patients with COLD or CLHF as compared to normal subjects, and were inversely correlated to haemoglobin concentrations. In patients with COLD or CLHF, plasma EPO was negatively correlated with both RBF and renal oxygen delivery (ROD) and positively correlated with filtration fraction. Plasma EPO was not correlated with glomerular filtration rate, fractional excretion of sodium, PO2 or PCO2. Among the patients with COLD, those with polycythemia (haemoglobin > 150 g L-1) had lower plasma EPO and higher RBF and ROD values than those with normocythemia (haemoglobin < or = 150 g L-1). Taken together, our data suggest that in patients with COLD or CLHF the critical determinant for EPO production is impairment of renal haemodynamics.

N-Cadherin: structure, function and importance in the formation of new intercalated disc-like cell contacts in cardiomyocytes.

N-Cadherin belongs to a superfamily of calcium-dependent transmembrane adhesion proteins. It mediates adhesion in the intercalated discs at the termini of cardiomyocytes thereby serving as anchor for myofibrils at cell-cell contacts. A large body of data on the molecular structure and function of N-cadherin exists, however, little is known concerning spatial and temporal interactions between the different junctional structures during formation of the intercalated disc and its maturation in postnatal development. The progression of compensated left ventricular hypertrophy to congestive left heart failure is accompanied by intercalated disc remodeling and has been demonstrated in animal models and in patients. The long-term culture of adult rat cardiomyocytes allows to investigate the development of de novo intercalated disc-like structures. In order to analyze the dynamics of the cytoskeletal redifferentiation in living cells, we used the expression of chimeric proteins tagged with the green fluorescent protein reporter. This technique is becoming a routine method in basic research and complements video time-lapse and confocal microscopy. Cultured cardiomyocytes have been used for a variety of studies in cell biology and pharmacology. Their ability to form an electrically coupled beating tissue-like network in culture possibly allows reimplantation of such cells into injured myocardium, where they eventually will form new contacts with the healthy muscle tissue. Several groups have already shown that cardiomyocytes can be grafted successfully into sites of myocardial infarcts or cryoinjuries. Autologous adult cardiomyocyte implantation, might indeed contribute to cardiac repair after infarction, thanks to advances in tissue engineering.

Preferences of veterinarians for drugs to treat heart disease in dogs and cats.

Responses (473) were collated from a questionnaire sent to 5054 veterinarians in Australia enquiring about drug preferences for treating cardiac disease in dogs and cats. When treating a small breed dog with endocardiosis and mild left congestive heart failure, 74% of 472 respondents used a diuretic, 67% a theophylline derivative, 27% a vasodilator and 20% a positive inotrope. Frusemide was the preferred diuretic and digoxin the preferred inotrope, but vasodilator use varied. Low sodium diets were "often recommended" by 71% of respondents. Propranolol was preferred to diltiazem for treating feline hypertrophic cardiomyopathy. Digoxin was clearly preferred for treating supraventricular dysrhythmias, while lignocaine and digoxin were preferred equally for ventricular dysrhythmias. Respondents appeared more willing than US veterinarians to use theophylline derivatives and prasozin, and less inclined to employ nitrates, hydralazine, inotropes other than digoxin, and low sodium diets.

Pathogenesis of pulmonary infarction

Pulmonary embolism discovered at autopsy is still as prevalent as previously reported In the last three to four decades. Only a certain percentage of pulmonary emboli result in pulmonary infarction. Recently published studies have suggested the importance of the size of the occluded pulmonary artery in the occurrence of infarction. Our study of 45 autopsy subjects in which there were pulmonary emboli shows a 31 percent incidence of pulmonary infarction. Clinicopathologic evaluation reveals a more common association of pulmonary infarction with occluded pulmonary artery branches of 3 mm in diameter or less, but emboli in larger arteries may show frequent extensions into their smaller distal branches without producing infarct. Pulmonary infarction also occurs more commonly in patients dying of cardiovascular or malignant diseases than it does in those dying of other diseases, and the combination of shock and congestive left heart failure appears to be the most significant hemodynamic risk factor in the development of pulmonary infarction. However, the increased risk of pulmonary infarction in patients with malignancy may not be accounted for by the existence of these two hemodynamic risk factors alone.

Clinical utility of gated cardiac blood pool imaging in congestive left heart failure

Our experience with gated cardiac blood pool imaging in the evaluation of congestive left-sided heart failure was reviewed in 82 patients. Ventricular contraction patterns, right and left ventricular size, and regional wall motion were evaluated from technetium-99m-albumin gated blood pool scans obtained in anterior and left anterior oblique projections. Patterns of ventricular function shown by scan were classified as follows: normal right and left ventricular size and contraction, normal left ventricular size with right ventricular enlargement, left ventricular volume overload, diffuse left ventricular hypokinesis, regional left ventricular asynergy, left ventricular aneurysm and hypertrophic cardiomyopathy. In 34 of 36 patients who underwent cardiac catheterization, the pattern of left ventricular dysfunction revealed by scan agreed with the findings on left ventriculography. Left ventricular end-diastolic diameters were significantly (p < 0.001) increased in patients with heart failure due to previous myocardial infarction, congestive cardiomyopathy, left ventricular volume overload and left ventricular pressure overload. Right ventricular diameters were increased predominantly among patients with congestive cardiomyopathy and mitral stenosis. Clinically, gated cardiac imaging was useful for (1) diagnostic screening prior to cardiac catheterization; (2) determination of the potential for improvement with surgical operation; and (3) prognostication from the severity of left ventricular dysfunction.

The renin-angiotensin-aldosterone system in rabbits with congestive heart failure produced by aortic constriction.

Severe constriction of the suprarenal abdominal aorta of 3-kg rabbits to 3.7+/-0.2 mm2 and maintenance of a daily sodium intake of 10 mE q by infusion of 0.9% sodium chloride resulted in a progressive increase in central ear arterial pressure to 106+/-3 (SEM) mm Hg (control=79+/-1). This was accompanied by a progressive increase in left ventricular end-diastolic pressure to 22+/-2 mm Hg (control=3+/-1), plasma renin activity to 21+/-5 ng of angiotensin/hour per ml (control=5+/-1), plasma aldosterone concentration to 99+/-23 pg/ml (control=14+/-4), and plasma sodium concentration to 142+/-1 mEq/liter (control=136+/-1). Urinary excretion of sodium decreased to 3.9+/-0.7 mEq/day and marked fluid retention occurred. We also found that these changes were accompanied by a decrease in hematocrit to 24+/-2% (control=40+/-1), formation of 36+/-9 ml of fluid in the thoracic cavity, 33+/-9 ml of ascites, pulmonary congestion and edema, hepatic congestion, and enlargement and hypertrophy of both the left and right ventricles. All rabbits died of ventricular failure at a time that was partly related to the degree of aortic constriction and that ranged from 2 to 12 days. The model we have established is chronic, highly reproducible, easy to produce, and inexpensive, and resembles the clinical syndrome of right and left congestive heart failure in man. Furthermore, the studies provide evidence for an important role of the renin-angiotensin-aldosterone system in the fluid retention that leads to pulmonary and systemic venous congestion after suprarenal aortic constriction.