50th anniversary historical article. Myocardial oxygen consumption: the quest for its determinants and some clinical fallout

Novel portable hypothermic machine perfusion preservation device enhances cardiac viability of donated human hearts

Introduction

Heart transplant remains the gold standard treatment for patients with advanced heart failure. However, the list of patients waiting for a heart transplant continues to increase. We have developed a portable hypothermic oxygenated machine perfusion device, the VP.S ENCORE®, to extend the allowable preservation time. The purpose of this study was to test the efficacy of the VP.S. ENCORE® using deceased donors derived hearts.

Methods

Hearts from brain-dead donors not utilized for transplant (n = 11) were offered for research from the Texas Organ Sharing Alliance (TOSA), South and Central Texas' Organ Procurement Organization (OPO) and were preserved in the VP.S ENCORE® for 4 (n = 2), 6 (n = 3), and 8 (n = 3) hours or were kept in static cold storage (SCS) (n = 3). After preservation, the hearts were placed in an isolated heart Langendorff model for reperfusion and evaluated for cardiac function.

Results

The mean donor age was 37.82 ± 12.67 with the youngest donor being 19 and the oldest donor being 58 years old. SCS hearts mean weight gain (%) was -1.4 ± 2.77, while perfused at 4 h was 5.6 ± 6.04, perfused at 6 h 2.1 ± 6.04, and 8 h was 7.2 ± 10.76. Venous and arterial lactate concentrations were less than 2.0 mmol/L across all perfused hearts. Left ventricular contractility (+dPdT, mmHg/s) for 4 h (1,214 ± 1,064), 6 (1,565 ± 141.3), and 8 h (1,331 ± 403.6) were within the range of healthy human heart function. Thus, not significant as compared to the SCS group (1,597 ± 342.2). However, the left ventricular relaxation (mmHg/s) was significant in 6-hour perfused heart (p < 0.05) as compared to SCS. Gene expression analysis of inflammation markers (IL-6, IL-1β) showed no significant differences between SCS and perfused hearts, but a 6-hour perfusion led to a downregulated expression of these markers.

Discussion

The results demonstrate that the VP.S ENCORE® device enhances cardiac viability and exhibits comparable cardiac function to a healthy heart. The implications of these findings suggest that the VP.S ENCORE® could introduce a new paradigm in the field of organ preservation, especially for marginal hearts.

Ventricular Unloading Using the ImpellaTM Device in Cardiogenic Shock

Cardiogenic shock (CS) remains a leading cause of hospital death. However, the use of mechanical circulatory support has fundamentally changed CS management over the last decade and is rapidly increasing. In contrast to extracorporeal membrane oxygenation as well as counterpulsation with an intraaortic balloon pump, ventricular unloading by the Impella™ device actively reduces ventricular volume as well as pressure and augments systemic blood flow at the same time. By improving myocardial oxygen supply and enhancing systemic circulation, the Impella device potentially protects myocardium, facilitates ventricular recovery and may interrupt the shock spiral. So far, the evidence supporting the use of Impella™ in CS patients derives mostly from observational studies, and there is a need for adequate randomized trials. However, the Impella™ device appears a promising technology for management of CS patients. But a profound understanding of the device, its physiologic impact and clinical application are all important when evaluating CS patients for percutaneous circulatory support. This review provides a comprehensive overview of the percutaneous assist device Impella™. Moreover, it highlights in depth the rationale for ventricular unloading in CS and describes practical aspects to optimize care for patients requiring hemodynamic support.

ECPella: Concept, Physiology and Clinical Applications

Addition of Impella on top of venoarterial extracorporeal membrane oxygenation (VA-ECMO) has gained wide interest as it might portend improved outcomes in patients with cardiogenic shock. This has been consistently reported in retrospective propensity-matched studies, case series, and meta-analyses. The pathophysiologic background is based on the mitigation of ECMO-related side effects and the additive benefit of myocardial unloading. In this perspective, thorough knowledge of these mechanisms is required to optimize the management of mechanical circulatory support with this approach and introduce best practices, as the interplay between the two devices and the implantation-explantation strategies are key for success.

Temperature and flow rate limit the optimal ex-vivo perfusion of the heart - an experimental study

Background

Ex-vivo heart perfusion can be utilized to study a variety of physiologic and molecular pathways in a controlled system outside of the body. It can also be used in clinical settings such as for organ preservation before transplantation. Myocardial oxygen consumption (MVO₂) correlates with energy production in the myocardium and can also be used to determine the balance between the oxygen supply and demand of the perfused heart. This study sought to determine an ex-vivo perfusion rate that matches the metabolic demands of the heart according to different temperatures and solution compositions (with and without the addition of erythrocytes), a flow below which the supply of oxygen is not sufficient to maintain an aerobic state of the perfused heart (“D_CRIT”).

Methods

Under general anesthesia, rat hearts were procured and preserved by perfusing with the University of Wisconsin Belzer machine perfusion system (UW Belzer MPS) solution saturated with 100% O₂. The key elements of this solution include supraphysiological potassium (to stop the heartbeat and reduce the cellular metabolic demand), starch, gluconate and mannitol (to maintain cell wall integrity), glucose (to sustain basal metabolism), and glutathione (to scavenge free radicals). Three groups of rat hearts (n = 7) were randomly allocated to be perfused at 15 °C, 22 °C or 37 °C, at a varying flow index (FI) starting from a minimum of 380 mL/min/100 g to less than 50 mL/min/100 g, decreasing by 50 mL/min/100 g at 10 min intervals while measuring the MVO₂ at each FI. Lactate was measured from coronary sinus samples to determine the onset of tissue hypoxia/anaerobic state.

Results

The D_CRIT at 15 °C was 99.9 ± 4.9 mL/min/100 g; however, at 22 °C and 37 °C we could not reach a D_CRIT. The myocardial oxygen demand could not be met at 22 °C and 37 °C with the maximum FI above 380 mL/min/100 g even when erythrocytes (10% V/V) were added to the solution. At 15 °C, the production of lactate was evident only below the D_CRIT, while at 22 °C lactate production was present at all flow indices.

Conclusions

Determining the D_CRIT for optimal ex-vivo perfusion of the heart is necessary to ensure adequate tissue oxygenation and limit anaerobic state. Temperatures employed above 15 °C limit the efficient ex-vivo perfusion preservation of heart with the UW Belzer MPS solution.

On pump harvesting of Left Internal Mammary Artery (LIMA) in unstable patients undergoing coronary artery bypass grafting (CABG) is a safe operative strategy: A pilot study

Objective:

To evaluate the clinical safety of left internal mammary artery (LIMA) harvesting in hemodynamically unstable patients after establishing cardiopulmonary bypass (CPB) in isolated coronary artery bypass graft (CABG) surgery.

Methods:

The prospective observational study was conducted at Chaudhry Pervaiz Elahi Institute of Cardiology, Multan, Pakistan, from December 2016 to August 2018. All patients undergoing isolated CABG surgery in which LIMA conduit was harvested after establishing cardiopulmonary bypass because of hemodynamic instability at induction of anaesthesia or during surgery were included in the study. Preoperative, operative and postoperative characteristics of the patients were recorded. Data was analyzed using SPSS 19.

Results:

In Forty nine patients including 39 male and 10 female, early CPB had to be established because of hemodynamic instability and afterwards LIMA was harvested. Out of 49, 30 patients presented with CCS class III angina. 37 (75.5%) patients were scheduled on elective coronary surgery waiting list. There were 39 (79.59%) patients who weaned off bypass on mild inotropic support and 4 (8.16%) patients needed IABP support. All patients had multi-vessel coronary artery disease. Mean number of grafts were 3.428±0.577, CPB time was 110.59±25.594 and hospital stay was 5.367±1.424.

Conclusions:

The study showed that LIMA can be safely harvested in unstable patients after establishing extracorporeal circulation and by using this operative strategy in patients who need urgent or emergent surgical coronary revascularization LIMA can be safely used as a conduit.

Myocardial insufficiency is related to reduced subunit 4 content of cytochrome c oxidase

BACKGROUND

Treatment of heart failure remains one of the most challenging task for intensive care medicine, cardiology and cardiac surgery. New options and better indicators are always required. Understanding the basic mechanisms underlying heart failure promote the development of adjusted therapy e.g. assist devices and monitoring of recovery. If cardiac failure is related to compromised cellular respiration of the heart, remains unclear. Myocardial respiration depends on Cytochrome c- Oxidase (CytOx) activity representing the rate limiting step for the mitochondrial respiratory chain. The enzymatic activity as well as mRNA expression of enzyme's mitochondrial encoded catalytic subunit 2, nuclear encoded regulatory subunit 4 and protein contents were studied in biopsies of cardiac patients suffering from myocardial insufficiency and dilated cardiomyopathy (DCM).

METHODS

Fifty-four patients were enrolled in the study and underwent coronary angiography. Thirty male patients (mean age: 45 +/- 15 yrs.) had a reduced ejection fraction (EF) 35 ± 12% below 45% and a left ventricular end diastolic diameter (LVEDD) of 71 ± 10 mm bigger than 56 mm. They were diagnosed as having idiopathic dilated cardiomyopathy (DCM) without coronary heart disease and NYHA-class 3 and 4. Additionally, 24 male patients (mean age: 52 +/- 11 yrs.) after exclusion of secondary cardiomyopathies, coronary artery or valve disease, served as control (EF: 68 ± 7, LVEDD: 51 ± 7 mm). Total RNA was extracted from two biopsies of each person. Real-time PCR analysis was performed with specific primers followed by a melt curve analysis. Corresponding protein expression in the tissue was studied with immune-histochemistry while enzymatic activity was evaluated by spectroscopy.

RESULTS

Gene and protein expression analysis of patients showed a significant decrease of subunit 4 (1.1 vs. 0.6, p < 0.001; 7.7 ± 3.1% vs. 2.8 ± 1.4%, p < 0.0001) but no differences in subunit 2. Correlations were found between reduced subunit 2 expression, low EF (r = 0.766, p < 0.00045) and increased LVEDD (r = 0.492, p < 0.0068). In case of DCM less subunit 4 expression and reduced shortening fraction (r = 0.524, p < 0.017) was found, but enzymatic activity was higher (0.08 ± 0.06 vs. 0.26 ± 0.08 U/mg, p < 0.001) although myocardial oxygen consumption continued to the same extent.

CONCLUSION

In case of myocardial insufficiency and DCM, decreased expression of COX 4 results in an impaired CytOx activity. Higher enzymatic activity but equal oxygen consumption contribute to the pathophysiology of the myocardial insufficiency and appears as an indicator of oxidative stress. This kind of dysregulation should be in the focus for the development of diagnostic and therapy procedures.

Clinical Features and Prognosis of Type 2 Myocardial Infarction in Acutely Decompensated Diabetic Patients

BACKGROUND

After the introduction of the universal definition of myocardial infarction, the incidence and diagnosis of type 2 myocardial infarction have risen dramatically, yet there are no clear guidelines on clinical management. Diabetic patients are at high risk for developing type 2 myocardial infarction when admitted in a decompensated state, and they are also at high risk for future cardiovascular events.

METHODS

We performed a retrospective analysis of 1058 patients admitted with diabetic ketoacidosis or hyperosmolar hyperglycemic state between 2011 and 2016. Patients were included if they had cardiac troponin I measured within 24 hours of admission, were older than 18 years of age, and had no evidence of acute coronary syndrome on admission. Baseline characteristics, admission laboratory test results, major adverse cardiovascular events, cardiac stress testing, and coronary angiography data up to 1 year after admission were reviewed. Patients were categorized into 2 groups: those with and those without type 2 myocardial infarction. The study had 2 endpoints: mortality and major adverse cardiac events (MACE) at 1 year and an abnormal result on stress test or coronary angiography at 1 year.

RESULTS

Of the 845 patients who met the inclusion criteria, 133 patients (15%) had type 2 myocardial infarction on admission. Patients with type 2 myocardial infarction were at a significantly higher risk for mortality and MACE at 1 year than those without. Patients with type 2 myocardial infarction were also at higher risk for developing an abnormal result on stress test or coronary angiography within 1 year of admission as compared with those without type 2 myocardial infarction (40% vs 24%; odds ratio 2; P = .0699).

CONCLUSION

Acutely decompensated diabetic patients with type 2 myocardial infarction are at increased risk for death and MACE. These patients may also be at risk for undiagnosed coronary artery disease.

Heart Rate Modification of Cardiac Output Following Cardiac Surgery: The Importance of Cardiac Time Intervals

OBJECTIVES

Inadequate cardiac output is associated with a poor outcome following cardiac surgery and is generally modified by the use of positive inotropic agents, volume resuscitation, and pacing. Echocardiography-guided pacemaker optimization is used in the outpatient setting, using different variables including total isovolumic time and the Tei index. We sought to determine the acute impact of heart rate on cardiac electromechanics, cardiac output, and stroke volume in the perioperative setting.

DESIGN

Observational study.

SETTING

Cardiothoracic adult intensive care department.

PATIENTS

Twenty-four sequential patients admitted after cardiac surgery.

INTERVENTIONS

Patients with pacemaker set by the treating anesthesiologist using hemodynamic parameters in theatre, within 4 hours of returning to intensive care, they were reassessed using transthoracic echocardiography. A comprehensive baseline echocardiographic study was performed at the clinician set RR interval and at heart rates from 70 to 110 beats/min, in increments of 10 beats/min. Pearson correlation coefficients were used to assess relationships between the measurements.

MEASUREMENTS AND MAIN RESULTS

Cardiac output and cardiac index were increased significantly in 79% patients using echocardiography-guided pacemaker optimization (2.21 L/min [± 0.97] and 1.2 L/min/m [± 0.52]). The echocardiography-driven cardiac output optimization protocol led to a significant reduction of total isovolumic time with concurrent increase of cardiac output and cardiac index in the overall population (p < 0.001). There was no consistent correlation between changes in RR interval and stroke volume, cardiac output, or cardiac index in the overall population. A strong negative correlation was found between the left ventricular total isovolumic time and stroke volume, cardiac output, and cardiac index in all groups.

CONCLUSION

Echocardiography-guided heart rate optimization results in a significant increase in cardiac output when compared with clinically derived pacing settings in the postoperative period. The optimal heart rate should be individualized for each patient, and total isovolumic time is the echocardiographic index with the highest sensitivity to determine the optimal hemodynamic profile.

Prognostic significance of myocardial energy expenditure and myocardial efficiency in patients with heart failure with reduced ejection fraction

In heart failure with reduced ejection fraction (HFrEF) patients, myocardial blood flow (MBF), myocardial energy expenditure (MEE), myocardial efficiency has been poorly evaluated because of the necessity of invasive procedures in the determination of these parameters. Transthoracic echocardiography (TTE) can provide reliable data for MEE, MBF (via coronary sinus (CS) flows). Also, myocardial efficiency can be evaluated by the MEE to MBF ratio. We aim to assess MBF, MEE and energy efficiency and the prognostic value of these parameters in HFrEF. In this prospective study, a total of 80 patients with HFrEF due to either ischemic or non-ischemic etiology and 20 healthy control subjects were included. Median follow-up duration was 901 (27-1004) days. MBF was calculated via coronary sinus blood flow. MEE was measured from circumferential end-systolic stress, stroke volume and left ventricular ejection time. MEE to MBF ratio was determined as MEf. Primary composite end-point (CEP) was cardiovascular mortality, heart transplantation or mechanical circulatory support. MEE and MEf were lower and MBF per minute was higher in HF group compared to control subjects whereas MBF per 100 g left ventricular mass was not different. MEE and MEf have significantly negative correlation with troponin I, BNP, uric acid and positive correlation with epicardial fat thickness. In Cox regression analysis, per one calorie decrease of MEE was associated 4.3 times increased risk [HR 4.396 (95% CI 1.230-15.716)] and per one percent decrease of MEf was associated 3.3 times increased risk of CEP [HR 3.343 (95% CI 1.025-10.905)]. Our study demonstrated that while MEE and MEf diminished in HFrEF, MBF preserved with the symptomatic progression of HF. MEE and MEf were found to be associated with important prognostic markers and independent predictors of CEP in HFrEF. Evaluation of MEE, MBF and MEf with echocardiography may provide an additional data regarding prognostic assessment of HFrEF population.

EMPA-REG OUTCOME: The Cardiologist's Point of View

Cardiologists could view empagliflozin as a cardiovascular drug that also has a beneficial effect on reducing hyperglycemia in patients with type 2 diabetes mellitus (T2DM). The effects of empagliflozin in lowering the risk of cardiovascular death and hospitalization for heart failure in T2DM patients with high cardiovascular risk during the recent Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) trial may be explained principally in terms of changes to cardiovascular physiology; namely, by the potential ability of empagliflozin to reduce cardiac workload and myocardial oxygen consumption by lowering blood pressure, improving aortic compliance, and improving ventricular arterial coupling. These concepts and hypotheses are discussed in this report.

EMPA-REG OUTCOME: The Cardiologist's Point of View

Cardiologists could view empagliflozin as a cardiovascular drug that also has a beneficial effect on reducing hyperglycemia in patients with type 2 diabetes mellitus (T2DM). The effects of empagliflozin in lowering the risk of cardiovascular death and hospitalization for heart failure in T2DM patients with high cardiovascular risk during the recent Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients-Removing Excess Glucose (EMPA-REG OUTCOME) trial may be explained principally in terms of changes to cardiovascular physiology; namely, by the potential ability of empagliflozin to reduce cardiac workload and myocardial oxygen consumption by lowering blood pressure, improving aortic compliance, and improving ventricular arterial coupling. These concepts and hypotheses are discussed in this report.

Heart rate variables in the Vascular Quality Initiative are not reliable predictors of adverse cardiac outcomes or mortality after major elective vascular surgery

OBJECTIVE

Heart rate (HR) parameters are known indicators of cardiovascular complications after cardiac surgery, but there is little evidence of their role in predicting outcome after major vascular surgery. The purpose of this study was to determine whether arrival HR (AHR) and highest intraoperative HR are associated with mortality or major adverse cardiac events (MACEs) after elective vascular surgery in the Vascular Quality Initiative (VQI).

METHODS

Patients undergoing elective lower extremity bypass (LEB), aortofemoral bypass (AFB), and open abdominal aortic aneurysm (AAA) repair in the VQI were analyzed. MACE was defined as any postoperative myocardial infarction, dysrhythmia, or congestive heart failure. Controlled HR was defined as AHR <75 beats/min on operating room arrival. Delta HR (DHR) was defined as highest intraoperative HR - AHR. Procedure-specific MACE models were derived for risk stratification, and generalized estimating equations were used to account for clustering of center effects. HR, beta-blocker exposure, cardiac risk, and their interactions were explored to determine association with MACE or 30-day mortality. A Bonferroni correction with P < .004 was used to declare significance.

RESULTS

There were 13,291 patients reviewed (LEB, n = 8155 [62%]; AFB, n = 2629 [18%]; open AAA, n = 2629 [20%]). Rates of any preoperative beta-blocker exposure were as follows: LEB, 66.5% (n = 5412); AFB, 57% (n = 1342); and open AAA, 74.2% (n = 1949). AHR and DHR outcome association was variable across patients and procedures. AHR <75 beats/min was associated with increased postoperative myocardial infarction risk for LEB patients across all risk strata (odds ratio [OR], 1.4; 95% confidence interval [CI], 1.03-1.9; P = .03), whereas AHR <75 beats/min was associated with decreased dysrhythmia risk (OR, 0.42; 95% CI, 0.28-0.63; P = .0001) and 30-day death (OR, 0.50; 95% CI, 0.33-0.77; P = .001) in patients at moderate and high cardiac risk. These HR associations disappeared in controlling for beta-blocker status. For AFB and open AAA repair patients, there was no significant association between AHR and MACE or 30-day mortality, irrespective or cardiac risk or beta-blocker status. DHR and extremes of highest intraoperative HR (>90 or 100 beats/min) were analyzed among all three operations, and no consistent associations with MACE or 30-day mortality were detected.

CONCLUSIONS

The VQI AHR and highest intraoperative HR variables are highly confounded by patient presentation, operative variables, and beta-blocker therapy. The discordance between cardiac risk and HR as well as the lack of consistent correlation to outcome makes them unreliable predictors. The VQI has elected to discontinue collecting AHR and highest intraoperative HR data, given insufficient evidence to suggest their importance as an outcome measure.

Increasing the tolerance of DCD hearts to warm ischemia by pharmacological postconditioning

Donation after circulatory death (DCD) offers a potential additional source of cardiac allografts. We used a porcine asphyxia model to evaluate viability of DCD hearts subjected to warm ischemic times (WIT) of 20–40 min prior to flushing with Celsior (C) solution. We then assessed potential benefits of supplementing C with erythropoietin, glyceryl trinitrate and zoniporide (Cs), a combination that we have shown previously to activate ischemic postconditioning pathways. Hearts flushed with C/Cs were assessed for functional, biochemical and metabolic recovery on an ex vivo working heart apparatus. Hearts exposed to 20-min WIT showed full recovery of functional and metabolic profiles compared with control hearts (no WIT). Hearts subjected to 30- or 40-min WIT prior to C solution showed partial and no recovery, respectively. Hearts exposed to 30-min WIT and Cs solution displayed complete recovery, while hearts exposed to 40-min WIT and Cs solution demonstrated partial recovery. We conclude that DCD hearts flushed with C solution demonstrate complete recovery up to 20-min WIT after which there is rapid loss of viability. Cs extends the limit of WIT tolerability to 30 min. DCD hearts with ≤30-min WIT may be suitable for transplantation and warrant assessment in a transplant model.

Assessment of coronary blood flow in the cardiac catheterization laboratory

Coronary blood flow is tightly autoregulated but is subject to epicardial and microvascular obstruction, primarily owing to coronary atherosclerosis. Because coronary flow limitation underlies ischemic heart disease, an understanding of coronary physiology is paramount. Measurement of coronary blood flow, once relegated to the research laboratory is now easily performed in the cardiac catheterization laboratory. In particular, the measurement of fractional flow reserve has been extensively studied and is an important adjunct to clinical decision making. Measurement of coronary flow informs clinicians of prognosis, guides revascularization therapy, and forms the basis of ongoing research in treatment of complex myocardial disease processes. Newer methods of assessing coronary flow measurements are undergoing validation for clinical use and should further enhance our ability to assess the importance of coronary flow in clinical disease.

Supply/demand type 2 myocardial infarction: should we be paying more attention?

Supply/demand (type 2) myocardial infarction is a commonly encountered clinical challenge. It is anticipated that it will be detected more frequently once high-sensitivity cardiac troponin assays are approved for clinical use in the United States. We provide a perspective that is based on available data regarding the definition, epidemiology, etiology, pathophysiology, prognosis, management, and controversies regarding type 2 myocardial infarction. Understanding these basic concepts will facilitate the diagnosis and treatment of these patients as well as ongoing research efforts.

The imbalance between coronary reserve and wall stress explains the severity of ventricular dysfunction in hypertension

BACKGROUND

The pathophysiologic role of coronary reserve impairment in hypertensive cardiac dysfunction is still debated. Previously, we demonstrated that satisfactory coronary vasodilatation may coexist with ventricular systolic dysfunction. It is conceivable that coronary reserve might otherwise be inappropriate for enhanced myocardial oxygen demand and may thus affect cardiac performance negatively.

HYPOTHESIS

Myocardial supply-demand imbalance contributes to the severity of ventricular dysfunction in hypertension (HTN).

METHODS

Fractional shortening (%) and end-systolic stress (10(3) x dyn x cm(-2)) were determined using echocardiography, and coronary reserve was calculated using transesophageal Doppler echocardiography. Coronary reserve/stress (cm2 x dyn(-1)) was utilized as a measure of supply-demand. Groups NL (20 healthy subjects), HTN1 (15 patients, fractional shortening > or = 30), HTN2 (19 patients, 20 < or = fractional shortening < 30), and HTN3 (21 patients, fractional shortening < 20) were constituted.

RESULTS

Compared with NL and HTN1, groups HTN2 and HTN3 had significantly (p < 0.05) greater end-systolic stress (NL = 72 +/- 16, HTN1 = 72 +/- 23, HTN2 = 143 +/- 32, HTN3 = 186 +/- 70). Coronary reserve was impaired in HTN3 alone (NL = 3.5 +/- 0.6, HTN1 = 3.4 +/- 1.0, HTN2 = 3.1 +/- 1.0, HTN3 = 2.6 +/- 1.1), but coronary reserve/stress was reduced in both HTN2 and HTN3 (NL = 50 +/- 12, HTN1 = 53 +/- 21, HTN2 = 22 +/- 7, HTN3 = 15 +/- 7). Stepwise regression analysis identified diastolic internal dimension, end-systolic stress, and coronary reserve/stress as independently associated with fractional shortening.

CONCLUSION

The imbalance between supply-demand explains the severity of hypertensive cardiac dysfunction and adds information to cardiac enlargement and elevated wall stress.