A Rapid Hemodynamic Monitor of Acute Ischemia during Cardiac Procedures: Changes in Relaxation via a Continuous Left Ventricular Pressure-Derivative Loop

Harry Silber, William M. Gottliebson, Douglas P. Lohmann, Willam R. Rank, Watts R. Webb, Peter V. Moulder

Research output: Contribution to journalArticle

Abstract

Background: Procedures that induce ischemic pre-conditioning during cardiac surgery will require a rapidly visualized hemodynamic monitor of acute ischemia. This study investigated the utility of a continuous loop tracing of left ventricular pressure (LVP) plotted against its derivative (dP/dt) as a visual beat-to-beat monitor of acute changes in myocardial relaxation due to global ischemia. Materials and methods: In 11 dogs, LVP, recorded via a micromanometer-tip catheter, was plotted against dP/dt as a continuous loop. The angle of the loop during relaxation is inversely related to tau, the time constant of isovolumic relaxation. The angle was measured before and during: infusion of dextran to increase pre-load, infusion of nitroprusside to reduce after-load, and a 30-s occlusion of the left main coronary artery to induce temporary global ischemia. Results: The relaxation angle of the loop did not change with dextran or nitroprusside infusion. During left main occlusion, the angle increased from 57 ± 7 degrees to 92 ± 3 degrees (P <0.001), reflecting markedly impaired relaxation. In five of nine cases, the angle became greater than 90 degrees, rendering the monoexponential model of pressure decay inapplicable. However, the beat-to-beat progression of the angle could easily be followed visually. Conclusions: The LVP-dP/dt loop is a readily visualized, continuous display of beat-to-beat changes in myocardial relaxation. It provides a dynamic and specific display of immediate changes in relaxation during global ischemia, even when the exponential model of pressure decay is not applicable. The loop may be useful for guiding procedures that induce ischemic pre-conditioning or post-conditioning during cardiac surgery.

Original languageEnglish (US)
Pages (from-to)107-113
Number of pages7
JournalJournal of Surgical Research
Volume134
Issue number1
DOIs
StatePublished - Jul 2006
Externally publishedYes

Fingerprint

Ventricular Pressure
Ischemia
Hemodynamics
Ischemic Preconditioning
Nitroprusside
Dextrans
Thoracic Surgery
Pressure
Coronary Vessels
Catheters
Dogs

Keywords

  • diastole
  • hemodynamic monitor
  • myocardial ischemia
  • myocardial relaxation

ASJC Scopus subject areas

  • Surgery

Cite this

A Rapid Hemodynamic Monitor of Acute Ischemia during Cardiac Procedures : Changes in Relaxation via a Continuous Left Ventricular Pressure-Derivative Loop. / Silber, Harry; Gottliebson, William M.; Lohmann, Douglas P.; Rank, Willam R.; Webb, Watts R.; Moulder, Peter V.

In: Journal of Surgical Research, Vol. 134, No. 1, 07.2006, p. 107-113.

Research output: Contribution to journalArticle

Silber, Harry ; Gottliebson, William M. ; Lohmann, Douglas P. ; Rank, Willam R. ; Webb, Watts R. ; Moulder, Peter V. / A Rapid Hemodynamic Monitor of Acute Ischemia during Cardiac Procedures : Changes in Relaxation via a Continuous Left Ventricular Pressure-Derivative Loop. In: Journal of Surgical Research. 2006 ; Vol. 134, No. 1. pp. 107-113.
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abstract = "Background: Procedures that induce ischemic pre-conditioning during cardiac surgery will require a rapidly visualized hemodynamic monitor of acute ischemia. This study investigated the utility of a continuous loop tracing of left ventricular pressure (LVP) plotted against its derivative (dP/dt) as a visual beat-to-beat monitor of acute changes in myocardial relaxation due to global ischemia. Materials and methods: In 11 dogs, LVP, recorded via a micromanometer-tip catheter, was plotted against dP/dt as a continuous loop. The angle of the loop during relaxation is inversely related to tau, the time constant of isovolumic relaxation. The angle was measured before and during: infusion of dextran to increase pre-load, infusion of nitroprusside to reduce after-load, and a 30-s occlusion of the left main coronary artery to induce temporary global ischemia. Results: The relaxation angle of the loop did not change with dextran or nitroprusside infusion. During left main occlusion, the angle increased from 57 ± 7 degrees to 92 ± 3 degrees (P <0.001), reflecting markedly impaired relaxation. In five of nine cases, the angle became greater than 90 degrees, rendering the monoexponential model of pressure decay inapplicable. However, the beat-to-beat progression of the angle could easily be followed visually. Conclusions: The LVP-dP/dt loop is a readily visualized, continuous display of beat-to-beat changes in myocardial relaxation. It provides a dynamic and specific display of immediate changes in relaxation during global ischemia, even when the exponential model of pressure decay is not applicable. The loop may be useful for guiding procedures that induce ischemic pre-conditioning or post-conditioning during cardiac surgery.",
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